CN111939868A

CN111939868A - Preparation method and application of adsorbent for efficiently removing heavy metal ions in wastewater based on electrolytic manganese residues

Info

Publication number: CN111939868A
Application number: CN202010836517.XA
Authority: CN
Inventors: 李佳; 马梦雨; 杜冬云; 邵黎; 魏华; 宋小龙
Original assignee: South Central University for Nationalities
Current assignee: South Central Minzu University
Priority date: 2020-05-29
Filing date: 2020-08-19
Publication date: 2020-11-17

Abstract

The invention relates to the technical field of environmental heavy metal removal, and particularly discloses a preparation method and application of an adsorbent for efficiently removing heavy metal ions Cd (II) and Pb (II) in wastewater by utilizing electrolytic manganese slag. The invention is a material based on electrolytic manganese slag, which mixes the electrolytic manganese slag and ore (at least one of calcite, serpentine and wollastonite), and uses carbonate and silicate components thereof to adsorb heavy metal ions in wastewater through modification, thereby rapidly removing the heavy metal ions in the wastewater, and finally realizing the high-efficiency rapid removal of Cd (II) and Pb (II) in the wastewater (in the prepared heavy metal solution, the removal rate of Cd (II) and Pb (II) can reach 95 percent), thereby having important environmental benefits and social values. The preparation method of the adsorption preparation of the invention is simple, convenient to operate, free of secondary pollution, good in adsorption effect and low in cost.

Description

Preparation method and application of adsorbent for efficiently removing heavy metal ions in wastewater based on electrolytic manganese residues

Technical Field

The invention relates to the technical field of environmental heavy metal removal, in particular to a preparation method and application of an adsorbent for efficiently removing heavy metal ions Cd (II) and Pb (II) in wastewater on the basis of electrolytic manganese residues.

Background

The mining industry plays an irreplaceable role in the economic development, however, it is accompanied by various environmental problems, among which the problem of ecological environmental pollution due to mining wastewater is the first place. According to statistics, the mining wastewater is one of the industries with the largest industrial wastewater discharge amount in China, and the discharge amount of the beneficiation wastewater per year is about 2 hundred million tons and accounts for 30 percent of the total amount of the wastewater discharged by the non-ferrous metal industry. If the main harmful heavy metal ions in the mining wastewater are directly discharged, the major harmful heavy metal ions can cause serious harm to the environment.

The electrolytic manganese slag is acid leaching slag generated after mineral powder is subjected to acid leaching by sulfuric acid in the process of producing electrolytic manganese. The electrolytic manganese industry is a high-pollution industry, and a large amount of solid waste residues are generated in the process of producing electrolytic manganese, so that the environmental pollution is caused. Although manganese slag is not listed in national hazardous waste records, the manganese slag contains a large amount of heavy metal elements, and the experimental results of flags and the like show that the leaching concentration of metal elements such As Pb, As, Zn and the like in solid waste slag is lower than the leaching toxicity standard.

In China, the pollution rate of water resources such as rivers, reservoirs, lakes and the like is up to 80.1 percent. The sources of heavy metal pollution in the environment are very wide, including mining, electroplating, chemical engineering, pharmacy and smeltingAnd the like, mainly from industrial production. The harmful heavy metals are lead, copper, zinc, nickel, cadmium and the like with the density of 4.5g/cm³The above metal elements. The great heavy metal pollution problem exists in the lake Tai in 2004, and the total Pb in the bottom mud of the lake Tai is²⁺Ion and total Cd²⁺The ion content exceeds the standard, and the national mild pollution level is reached. The molybdenum concentration of the Ujin pond reservoir in the Fenugreek island city exceeds the highest standard value by 13.7 times. The surface layer of the Huangpu river dry flow also has a serious heavy metal pollution problem, and Pb in sediments of the Huangpu river dry flow²⁺The ion content exceeds 1 time. Also analogous to this is Suzhou river, Cd²⁺Excess ion of 1.75 times and Hg²⁺The ions exceeded 1.62 times. And the pollution ratio of the river is as high as 80.1 percent on the whole. Historically there has been a serious tragic event in which heavy metal contamination has led to extensive damage to human health. For example, the famous bone pain event is large-area chronic cadmium poisoning of Japan residents caused by water resources polluted by cadmium-containing wastewater discharged by smelting plants. The water-bearing event causing the mercury poisoning of large area of residents is caused by that water-bearing factories are not treated and are good at discharging large amount of mercury-containing sewage. Therefore, the problem of water pollution caused by heavy metals is one of the problems which are closely concerned in our country and even the current environment work all over the world, and how to comprehensively treat industrial heavy metal wastewater and even recycle and recycle the heavy metals in the wastewater is one of the focuses of the close attention of the environmental protection science.

At present, various methods such as precipitation, electrocoagulation, plant extraction, ion exchange, reverse osmosis, electrodialysis, adsorption and the like are mainly used for treating heavy metal wastewater at home and abroad, wherein the adsorption method has the advantages of convenience in operation, high efficiency, low cost and the like, and becomes one of the research focuses of people. The key point of the adsorption method is the adsorbent, the currently commonly used adsorbents comprise biochar, clay mineral cellulose, molecular sieve and the like, Lishaming and the like research the adsorption of the magnetic chrysotile nanotube on Cd (II) and Pb (II), and the adsorption capacity of the magnetic chrysotile nanotube on Cd (II) and Pb (II) is 23.82 mg.g^-1And 27.64mg g^-1(ii) a M.Kobya et al studied the preparation of activated carbon from apricot stone to adsorb heavy metal ions from aqueous solutions, with Cd (II) and Pb (II) adsorbed to 33.57mg·g^-1And 22.84mg g^-1(ii) a Unuabonah et al, on the adsorption of Pb (II) and Cd (II) in aqueous solution onto sodium tetraborate-modified kaolin, showed that the adsorption of Cd (II) and Pb (II) by the modified kaolin was 14.39mg g^-1And 11.63mg g^-1(ii) a The three materials are different materials for adsorbing heavy metal, the effect is not obvious, and the electrolytic manganese slag contains muscovite and other similar silicate substances, so the prospect of removing the heavy metal ions in the wastewater by using the electrolytic manganese slag is wide.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a method for recycling the materials which are originally wastes, so that the heavy metal ions in the wastewater can be efficiently removed.

A preparation method of an adsorbent for efficiently removing heavy metal ions in wastewater based on electrolytic manganese slag comprises the following steps:

(1) mixing the electrolytic manganese slag and the ore, and adding the mixture in a ratio of (5-10) mL: 1g of deionized water, and stirring for 1-3h to obtain a mixed solution;

(2) standing the mixed solution obtained in the step (1), centrifuging at 3500-4500r/min for 10-30min, pouring out the supernatant, leaving solid, placing the solid in an oven at 60-80 ℃, drying for 12-36h, and taking out;

(3) putting the solid taken out in the step (2) into a muffle furnace, calcining for 1-3h, cooling and taking out;

(4) and (4) grinding the solid taken out in the step (3), and sieving the ground solid with a sieve of 80 to 120 meshes to obtain the adsorbent for later use.

Further, the ore is selected from at least one of calcite, serpentine and wollastonite.

Further, the mass ratio of the electrolytic manganese slag to the ore is (1.5-3): 1; preferably, the mass ratio is (2-2.5) to 1; most preferably, the mass ratio is 7: 3.

Further, the ore is calcite, and the calcining temperature is 600-800 ℃.

Further, the ore is serpentine, and the calcining temperature is 700-800 ℃.

Further, the ore is wollastonite, and the calcining temperature is 600-800 ℃.

Most preferably, the ore is calcite, the mass ratio of the electrolytic manganese slag to the calcite is 7:3, and the electrolytic manganese slag is calcined at 800 ℃ for 2 h.

Most preferably, the ore is serpentine, the mass ratio of the electrolytic manganese slag to the serpentine is 7:3, and the ore is calcined at 800 ℃ for 2 hours.

Most preferably, the ore is wollastonite, the electrolytic manganese slag and the wollastonite have the mass ratio of 7:3, and the ore is calcined at 800 ℃ for 2 hours.

Further, the wastewater is a water body containing heavy metal ions, and the heavy metal ions are Cd (II) and/or Pb (II).

An application of the adsorbent prepared by the preparation method in efficiently removing heavy metal ions in wastewater.

Preferably, the temperature of the wastewater body is normal temperature.

Preferably, the pH value of the water body is adjusted to 5-7 before the adsorbent is added into the wastewater.

Preferably, the initial concentration range of heavy metal ions in the wastewater is 25-650 mg/L.

Preferably, the adsorbent has an adsorption time of 1 to 360 minutes after addition to the wastewater.

The method for adsorbing heavy metal ions by the adsorbent adopts a static adsorption method, and the detection steps of the removal rate are as follows:

after adsorbing heavy metal ions by using an adsorbent, filtering, measuring the concentration of the residual heavy metal ions in the filtrate by using an atomic spectrophotometer, then calculating the removal rate of the heavy metal ions by the adsorbent according to the formula (1), and calculating the adsorption capacity of the heavy metal ions according to the formula (2).

R: the removal rate of heavy metal ions;

q: the adsorption capacity (mg/g) of the adsorbent for heavy metal ions;

c₀: initial heavy metal ion concentration (mg/L);

c: the concentration (mg/L) of residual heavy metal ions after adsorption;

v: volume (L) of solution containing heavy metal ions;

m: the weight (g) of the composite adsorbent was added.

According to the change of the removal rate of the adsorbent to the heavy metal ions and the change of the adsorption capacity of the adsorbent along with time when the adsorbent adsorbs the heavy metal ions with certain concentration, a relation curve of the removal rate and the change of the adsorption capacity along with time can be drawn, and the obtained balance time can represent the adsorption speed of the adsorbent to the heavy metal ions.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the adsorbent based on the electrolytic manganese slag has the characteristics of simple preparation method, convenience in operation, no secondary pollution, good adsorption effect and low cost, has excellent adsorption performance on toxic heavy metal ions at normal temperature, can reach adsorption balance in a short time, provides a new idea for resource utilization of the electrolytic manganese slag, and has important environmental benefits and good application prospects.

The invention is a material based on electrolytic manganese slag, which mixes the electrolytic manganese slag and ore (at least one of calcite, serpentine and wollastonite), and uses carbonate and silicate components thereof to adsorb heavy metal ions in wastewater through modification, thereby rapidly removing the heavy metal ions in the wastewater, and finally realizing the high-efficiency rapid removal of Cd (II) and Pb (II) in the wastewater (in the prepared heavy metal solution, the removal rate of Cd (II) and Pb (II) can reach 95 percent), thereby having important environmental benefits and social values.

Drawings

FIG. 1A is a graph showing the effect of adsorption time on the adsorption performance of cadmium ions, measured with the adsorbent obtained in example 1.

FIG. 1B is a graph showing the effect of initial pH on the adsorption performance of cadmium ions measured for the adsorbent obtained in example 1.

FIG. 2 is a graph showing the effect of adsorption time on the adsorption performance of lead ions measured for the adsorbent obtained in example 1.

FIG. 3 is a graph showing the effect of adsorption time on the adsorption performance of cadmium ions measured by the adsorbent obtained in example 2.

FIG. 4 is a graph showing the effect of adsorption time on the adsorption performance of lead ions measured by the adsorbent obtained in example 2.

FIG. 5 is a graph showing the effect of adsorption time on the adsorption performance of cadmium ions, measured with the adsorbent obtained in example 3.

FIG. 6 is a graph showing the effect of adsorption time on the adsorption performance of lead ions measured for the adsorbent obtained in example 3.

FIG. 7 is a graph showing the effect of adsorption time on the adsorption performance of cadmium ions, measured with the adsorbent obtained in example 4.

FIG. 8 is a graph showing the effect of adsorption time on the adsorption performance of lead ions measured for the adsorbent obtained in example 4.

FIG. 9 is a graph showing the effect of adsorption time on adsorption performance of cadmium ions, measured by electrolytic manganese slag (EMR).

FIG. 10 is a graph showing the influence of adsorption time on the adsorption performance of lead ions, which was measured by electrolytic manganese slag (EMR).

FIG. 11A is an XRD pattern of electrolytic manganese slag (EMR) and calcite, and FIG. 11B is an XRD pattern of F-EMR1 (obtained in example 1).

FIG. 12 is a graph showing the pore size distribution (A) and N of electrolytic manganese slag (EMR), calcite and F-EMR1 (obtained in example 1)₂Adsorption-desorption curve (B).

FIGS. 13A and 13B are SEM images of F-EMR1 (obtained in example 1).

FIG. 14 is an XPS plot of F-EMR1 (from example 1) before and after Cd (II) and Pb (II) removal; wherein, the chart A is a total spectrogram before and after adsorption, the chart B is a spectrogram for adsorbing Cd, and the chart C is a spectrogram for adsorbing lead.

FIGS. 15A1, 15A2 are SEM images of F-EMR5 (from example 5) at different magnification.

FIG. 16A is an XRD pattern of serpentine and FIG. 16B is an XRD pattern of F-EMR5 (obtained in example 5).

FIG. 17 is an XPS plot of F-EMR5 (from example 5) before and after Cd (II) and Pb (II) removal; wherein, the chart A is a total spectrogram before and after adsorption, the chart B is a spectrogram for adsorbing Cd, and the chart C is a spectrogram for adsorbing lead.

FIGS. 18A1, 18A2 are SEM images of F-EMR9 (from example 9) at different magnification.

FIG. 19A is the XRD pattern of wollastonite and FIG. 19B is the XRD pattern of F-EMR9 (obtained in example 9).

FIG. 20 is an XPS plot of F-EMR9 (from example 9) before and after Cd (II) and Pb (II) removal; wherein, the chart A is a total spectrogram before and after adsorption, the chart B is a spectrogram for adsorbing Cd, and the chart C is a spectrogram for adsorbing lead.

FIG. 21A is the XRD pattern of montmorillonite, and FIG. 21B is the XRD pattern of F-EMR13 (obtained in comparative example 2).

FIG. 22A is an XRD pattern of attapulgite, and FIG. 22B is an XRD pattern of F-EMR14 (obtained in comparative example 3).

Detailed Description

In the following examples, the starting materials used: the electrolytic manganese slag (EMR) is from China manganese big Inc. in Guangxi, and has a particle size of 149 μm; calcite, serpentine, wollastonite, attapulgite and montmorillonite are all from Yousio chemical Co., Ltd, and the particle size is 15 μm.

The electrolytic manganese residue, serpentine, calcite, wollastonite, attapulgite and montmorillonite were subjected to XRF testing (X-ray fluorescence spectrum analyzer: Zetium, Netherlands, PanalytalB.V) and analyzed for the weight percent of the components as shown in the following table:

in the following examples and comparative examples, solutions of heavy metal ions were prepared using salt and water, the concentrations being measured as heavy metal ions (Cd (II) or Pb (II)).

Example 1

A preparation method of an adsorption material for efficiently removing heavy metal ions in wastewater based on electrolytic manganese slag comprises the following steps:

(1) mixing 7g of electrolytic manganese slag and 3g of calcite, adding 50ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the calcite;

(2) standing the mixed solution of the electrolytic manganese slag and the calcite for 30min, transferring the mixed solution of the electrolytic manganese slag and the calcite into a 50ml centrifugal tube, centrifuging for 10min at 4000r/min, pouring out supernatant liquid, reserving solid, putting the solid into a 60 ℃ oven, drying for 24h, and taking out;

(3) putting the solid taken out in the step (2) into a muffle furnace, calcining at 800 ℃ for 2h, cooling to room temperature, and taking out;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 1, designated as F-EMR 1.

FIG. 11A is an XRD pattern of electrolytic manganese slag (EMR) and calcite, and FIG. 11B is an XRD pattern of F-EMR1 (obtained in example 1); the figures in the figure are respectively: 1-calcium carbonate, 2-dolomite, 3-hydrated silico-calcium-manganese stone, 4-quartz, 5-gypsum, 6-whinesite and 7-ferro-calcium rosepside;

as can be seen from the figure, the calcite mainly consists of calcium carbonate and dolomite, and the components are simpler; the crystal phase of the electrolytic manganese slag mainly comprises quartz, gypsum, silico-calcium-manganese hydrate, whitlockite and ferro-calcium rosepsite; the crystalline phase of F-EMR1 is amorphous with anhydrite (CaSO) predominating therein₄) Quartz (SiO)₂) Calcium hydroxide (Ca (OH)₂) Akermanite (Ca)₂Mg(Si₂O₇) Calcium rosette (Bustamite, Ca)₂MnSi₂O₆) Calcium carbonate, silicates, magnetite and ramsdellite.

As can be seen from FIG. 12, EMR and calcite have similar nitrogen adsorption-desorption isotherms, are both type (II) adsorption, and have obvious direct current circuits at relative pressures of 0.60-1.0, while the hysteresis loop of F-EMR1 is larger and longer, which indicates that the mesostructure of the adsorbent surface is increased along with the increase of the types of the pore structures.

The physical structure parameters of EMR, calcite and F-EMR1 are as follows:

material	BET(m²g^-1)	Average pore diameter (nm)	Pore volume (cm)³g^-1)
				EMR	3.480	15.877	0.014
Calcite	1.215	20.614	0.006
				F-EMR1	11.753	18.420	0.057

As can be seen from FIGS. 13A and 13B (SEM), F-EMR1 shows an irregular layered, blocky structure and a stack of loose agglomerates, accompanied by some mesopores, with the lamellae curled into a scaly form, and a channel structure can be seen, with a large surface area, and the surface of F-EMR1 consisting of a non-uniform crystal structure.

From the XPS total spectrum, it can be seen that: compared with the prior art, the heavy metal ions are adsorbed by the adsorbent, and then the Mg2p, Ca2p and Fe2p are changed.

According to the high-resolution Cd3d spectrum, the binding energy of Cd3d 5/2 is at 405.6eV, which may be attributed to the binding of Cd (II) ions to hydroxide and carbonate ions, forming hydroxide and carbonate precipitates. The binding energy of Cd3d 3/2 is at 412.3eV, which may be attributed to the binding of cadmium (II) ions to silicate ions, forming a precipitate.

According to the high-resolution Pb4f spectrum, the adsorbed Pb (II) presents 138.2eV and 143.1eV corresponding to the characteristic peaks of Pb4f7/2 and Pb4f5/2, respectively. In the spectrograms, it can be seen that the main composition of lead of the adsorbent after adsorbing Pb (II) is PbCO₃、Pb(OH)₂、PbSO₄、PbSiO₃、Pb₂SiO₄And so on, the adsorbent forms mainly lead carbonate, lead sulfate, lead hydroxide, lead silicate precipitates after adsorbing Pb (II).

The prepared adsorbent is subjected to a heavy metal adsorption test, and the specific experimental steps are as follows:

0.050g of the adsorbent 1 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 300mg/L, and adsorbed by stirring at room temperature for 1 minute, and after filtration, the content of cadmium ions remaining in the solution was measured by an atomic spectrophotometer. Under the same conditions, the adsorption time was varied to 5 minutes, 10 minutes, 20 minutes, 30 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in table 1. The results showed that the removal rate was 99.00% under the condition of 120 minutes of adsorption and the adsorption capacity was 297.00 mg/g.

TABLE 1 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	292.11	97.37
5	294.81	98.27
			10	294.99	98.33
20	295.71	98.57
			30	296.19	98.73
60	296.25	98.75
			120	297.00	99.00

With 0.1mol/L HNO₃Adjusting the pH values of the tetrahydrate cadmium nitrate solution with initial concentration of 450mg/L to be 2.0, 3.0, 4.0, 5.0, 6.0 and 7.0 by 0.1mol/L NaOH, putting 50mL of the solution into different 50mL centrifuge tubes, adding F-EMR10.050g into each group of the solution, oscillating for 24 hours at the temperature of 30 ℃ and the speed of 180r/min, taking out the supernatant, passing through a 0.45 mu m filter membrane, and measuring the concentration of Cd in the solution by adopting an atomic absorption spectrophotometer. According to the adsorption before and after dissolutionAnd (4) calculating the removal rate and the adsorption capacity of Cd by the concentration difference of Cd in the solution.

TABLE 2 Effect of initial pH on adsorption Properties of cadmium ions of F-EMR

pH	Adsorption capacity (mg/g)	Removal Rate (%)
			2	159.30	35.40
3	169.44	37.65
			4	339.85	75.52
5	396.41	88.09
			6	435.69	96.82
7	432.59	96.13

0.050g of adsorbent 1 was put into 50mL of a lead nitrate solution having an initial concentration of 610mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 95.875% and the adsorption capacity was 584.837mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 3.

TABLE 3 influence of adsorption time on adsorption Properties of lead ions

As can be seen from fig. 2, the removal rate and the adsorption capacity both greatly increase first with the increase of the adsorption time from 0min to 30min, then increase slowly, reach 96.729% adsorption equilibrium at 60min, and the adsorption equilibrium is not broken until 120min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, thus obtaining that the equilibrium adsorption time of the adsorbent 1 is 60min when the initial concentration of lead ions is 610 mg/L.

The adsorbent removes heavy metals, and the main mechanism is as follows: when calcite is dissolved in water, calcium oxide in the calcite can react with the water to generate calcium hydroxide, and the calcium hydroxide is attached to the electrolytic manganese slag to enable the electrolytic manganese slag to have hydroxyl radicals, and the reaction is as follows:

CaO+H₂O→Ca(OH)₂

2Ca(OH)₂+SiO₂→Ca₂SiO₄+2H₂O

and then after a series of modifications, manganese oxide in the electrolytic manganese slag reacts with oxygen to generate manganese dioxide, and ferrous sulfide reacts with oxygen to generate ferroferric oxide, wherein the reactions are as follows:

2CaCO₃+SiO₂→Ca₂SiO₄+2CO₂

2MnO+O₂→2MnO₂

3FeS+5O₂→Fe₃O₄+3SO₂

according to the reports of relevant documents, manganese and iron in manganese dioxide and ferroferric oxide have electrostatic attraction effect on heavy metals, namely X-is Fe or Mn

–X–OH+OH-＝–X–O^-+H₂O

–X–O^-+M²⁺＝–X–OM

Therefore, when heavy metal Cd or lead is adsorbed, the adsorption mechanism mainly comprises electrostatic attraction and ion exchange and surface precipitation, the electrostatic attraction mainly comprises the action of manganese dioxide and ferroferric oxide, the ion exchange is carried out by exchanging calcium ions with heavy metal ions, and silicate ions, sulfate ions and hydroxide ions are combined to generate the surface precipitation.

2OH-+M²⁺→M(OH)₂

MgSiO₃+M²⁺→MSiO₃+Mg²⁺

Ca₂SiO₄+M²⁺→M₂SiO₄+2Ca²⁺

Pb²⁺+SO₄ ^2-→PbSO₄

Example 2

(1) mixing 6g of electrolytic manganese slag and 4g of calcite, adding 50ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the calcite;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 2, which is recorded as F-EMR 2.

0.050g of adsorbent 2 was put into 50mL of cadmium nitrate tetrahydrate solution with initial concentration of 140mg/L, stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 99.193% and the adsorption capacity was 138.870mg/g under such a condition. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in table 4.

TABLE 4 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	138.82	99.15
5	138.89	99.21
			10	138.86	99.19
20	138.92	99.23
			30	138.87	99.20
60	138.91	99.22
			120	139.00	99.28

0.050g of adsorbent 2 was put into 50mL of lead nitrate solution having an initial concentration of 310mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 91.888% and the adsorption capacity was 284.853mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in table 5.

TABLE 5 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity: (mg/g)	Removal Rate (%)
			1	268.91	86.75
5	278.85	89.95
			10	281.35	90.76
20	282.24	91.05
			30	284.85	91.89
60	289.62	93.43
			120	291.97	94.18

As can be seen from fig. 4, the removal rate and the adsorption capacity both increase first and then increase slowly with the increase of the adsorption time from 0min to 30min, and reach 93.426% adsorption equilibrium at 60min, and the adsorption equilibrium is not broken until 120min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, thereby obtaining that the equilibrium adsorption time of the adsorbent 2 is 60min when adsorbing lead ions with the initial concentration of 310 mg/L.

Example 3

(1) mixing 13g of electrolytic manganese slag and 7g of calcite, adding 100ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the calcite;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 3, which is recorded as F-EMR 3.

0.050g of adsorbent 3 was put into 50mL of cadmium nitrate tetrahydrate solution with initial concentration of 140mg/L, stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 99.079% and the adsorption capacity was 138.710mg/g under such a condition. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 6.

TABLE 6 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	137.92	98.51
5	138.25	98.75
			10	138.58	98.99
20	138.64	99.03
			30	138.71	99.08
60	138.88	99.20
			120	138.92	99.23

0.050g of adsorbent 3 was put into 50mL of lead nitrate solution having an initial concentration of 310mg/L, and stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 91.850% and the adsorption capacity was 284.736mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 7.

TABLE 7 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	260.97	84.19
5	272.45	87.89
			10	273.54	88.24
20	278.00	89.68
			30	284.74	91.85
60	284.73	91.85
			120	285.60	92.13

As can be seen from fig. 6, the removal rate and the adsorption capacity both increase first and then increase slowly with the increase of the adsorption time from 0 to 30min, and reach 91.850% adsorption equilibrium at 30min, and the adsorption equilibrium is not broken until 120min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, thereby obtaining that the equilibrium adsorption time of the adsorbent 3 is 30min when adsorbing lead ions with the initial concentration of 310 mg/L.

Example 4

(3) putting the solid taken out in the step (2) into a muffle furnace, calcining at 600 ℃ for 2h, cooling to room temperature, and taking out;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 4, which is marked as F-EMR 4.

0.050g of adsorbent 4 was put into 50mL of cadmium nitrate tetrahydrate solution having an initial concentration of 140mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 79.571% and the adsorption capacity was 111.400mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes, 180 minutes and 240 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 8.

TABLE 8 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	105.62	75.44
5	105.68	75.49
			10	106.80	76.28
20	109.62	78.30
			30	111.40	79.57
60	113.04	80.74
			120	120.46	86.04
180	129.10	92.22
			240	130.02	92.87

As can be seen from fig. 7, the removal rate and the adsorption capacity both greatly increase first with the increase of the adsorption time from 0min to 60min, then increase slowly, reach 92.466% adsorption equilibrium at 180min, and the adsorption equilibrium is not broken until 240min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, thus obtaining that the equilibrium adsorption time of the adsorbent 4 is 180min when adsorbing cadmium ions with the initial concentration of 140 mg/L.

0.050g of adsorbent 4 was put into 50mL of lead nitrate solution having an initial concentration of 310mg/L, and stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 91.655% and the adsorption capacity was 284.130mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 9.

TABLE 9 influence of adsorption time on adsorption Properties of lead ions

As can be seen from fig. 8, the removal rate and the adsorption capacity both greatly increase first with the increase of the adsorption time from 0min to 60min, and then increase slowly, and reach 97.809% of adsorption equilibrium at 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption, and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 4 at the initial adsorption concentration of 310mg/L of lead ions is 120 min.

Example 5

(1) mixing 7g of electrolytic manganese slag and 3g of serpentine, adding 50ml of deionized water, stirring by adopting magnetons, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the serpentine;

(2) standing the mixed solution of the electrolytic manganese slag and the serpentine for 30min, transferring the mixed solution of the electrolytic manganese slag and the serpentine into a 50ml centrifugal tube, centrifuging for 10min at 4000r/min, pouring out supernatant liquid, reserving solid, putting the solid into a 60 ℃ oven, drying for 24h, and taking out;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 5, which is designated as F-EMR 5.

The physical structure parameters of EMR, serpentine and F-EMR5 are as follows:

material	BET(m²g^-1)	Average pore diameter (nm)	Pore volume (cm)³g^-1)
				EMR	3.480	15.877	0.014
Serpentine stone	7.156	11.851	0.021
				F-EMR5	11.998	18.370	0.055

As can be seen from FIG. 15A1(SEM), the shape of the F-EMR5 is irregular sheet-like or block-like structure, the surface of the F-EMR5 has some attachments thereon, and the attachment is loose, so that the adsorption sites are increased, and after the F-EMR5 is enlarged (FIG. 15A2), the structure is loose, and a plurality of pores are formed on the surface, so that the external surface area of the adsorption material is increased.

FIG. 16A is an XRD pattern of serpentine and FIG. 16B is an XRD pattern of F-EMR5 (obtained in example 5); as can be seen, serpentine is mainly composed of a-dolomite, b-calcium silicate, c-magnesium silicate, d-calcium sulfate, e-aluminum silicate, f-Ca (Mg, Fe) (CO)₃)₂G-calcium oxide, h-magnesium oxide; the main components of the F-EMR5 are silicon dioxide, calcium sulfate, hematite, calcium silicate, manganese dioxide, magnesium silicate, FeOOH, ferroferric oxide and the like.

FIG. 17 is an XPS plot of F-EMR5 (from example 5) before and after Cd (II) and Pb (II) removal; wherein, the chart A is a total spectrogram before and after adsorption, B is a spectrogram for adsorbing Cd, and C is a spectrogram for adsorbing lead;

from the XPS total spectrum, it can be seen that: compared with the method before removal, the method changes Mg2p, Ca2p and Fe2p after heavy metal ions are adsorbed.

According to the high-resolution Cd3d spectrum, the binding energy of Cd3d 5/2 is at 405.6eV, which is attributed to the binding of Cd (II) ions to hydroxide and carbonate ions, forming hydroxide and carbonate precipitates. The binding energy of Cd3d 3/2 is at 412.3eV, which may be attributed to the binding of cadmium (II) ions to silicate ions, forming a precipitate.

According to the high-resolution Pb4f spectrum, the adsorbed Pb (II) presents 138.2eV and 143.1eV corresponding to the characteristic peaks of Pb4f7/2 and Pb4f5/2, respectively. In the spectrograms, it can be seen that the main component of lead is PbCO₃、Pb(OH)₂、PbSO₄、PbSiO₃、Pb₂SiO₄And so on, the adsorbent forms mainly lead carbonate, lead sulfate, lead hydroxide, lead silicate precipitates after adsorbing Pb (II).

0.050g of adsorbent 5 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 100mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 64.62% and the adsorption capacity was 64.62mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes, 180 minutes and 240 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 10.

TABLE 10 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacityAmount (mg/g)	Removal Rate (%)
			1	49.33	49.33
5	51.65	51.65
			10	55.35	55.35
20	59.01	59.01
			30	64.62	64.62
60	70.22	70.20
			120	83.69	83.69
180	95.07	95.07
			240	98.05	98.05

0.050g of adsorbent 5 was put into 50mL of lead nitrate solution having an initial concentration of 610mg/L, and stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 80.680% and the adsorption capacity was 492.145mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes and 30 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 11. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and then slowly increased along with the increase of the adsorption time in 0-20min, 90.031% of adsorption equilibrium is reached in 180min, and the adsorption equilibrium is not broken until 240min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 5 is 180min when the initial adsorption concentration is 610mg/L lead ions.

TABLE 11 influence of adsorption time on adsorption Properties of lead ions

Example 6

(1) mixing 6g of electrolytic manganese slag and 4g of serpentine, adding 50ml of deionized water, stirring by adopting magnetons, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the serpentine;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 6, which is designated as F-EMR 6.

0.050g of adsorbent 6 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 96.980% and the adsorption capacity was 24.245mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 12. It can be seen that the removal rate and the adsorption capacity reach 96.7% at 1min, and the adsorption is not broken until 120min, which indicates that the adsorption is relatively stable.

TABLE 12 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	24.18	96.70
5	24.19	96.74
			10	24.19	96.76
20	24.19	96.76
			30	24.25	96.98
60	24.30	97.20
			120	24.37	97.48

0.050g of the adsorbent 6 was put into 50mL of a lead nitrate solution having an initial concentration of 140mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured by an atomic spectrophotometer, and the result showed that the removal rate was 86.186% and the adsorption capacity was 120.66mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 13. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-30min along with the increase of the adsorption time, 91.314% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 6 is 120min when the initial adsorption concentration is 140mg/L of lead ions.

TABLE 13 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	21.31	15.22
5	48.44	34.60
			10	55.40	39.57
20	72.71	51.94
			30	120.66	86.19
60	121.45	86.75
			120	127.84	91.31
180	128.85	92.04

Example 7

(1) mixing 13g of electrolytic manganese slag and 7g of serpentine, adding 100ml of deionized water, stirring by adopting magnetons, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the serpentine;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 7, which is designated as F-EMR 7.

0.050g of adsorbent 7 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 96.540% and the adsorption capacity was 24.135mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 14. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and then slowly increased along with the increase of the adsorption time within 0-10min, 96.080% of adsorption equilibrium is reached within 20min, and the adsorption equilibrium is not broken until 120min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 7 is 20min when the initial concentration of the adsorbent is 25mg/L cadmium ions.

TABLE 14 influence of adsorption time on adsorption Properties of cadmium ions

0.050g of adsorbent 7 was put into 50mL of lead nitrate solution having an initial concentration of 180mg/L, and stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 58.824% and the adsorption capacity was 105.884mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 15. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 94.540% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 7 is 120min when the initial concentration of lead ions is 180 mg/L.

TABLE 15 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	30.26	16.81
5	46.57	25.87
			10	70.77	39.32
20	79.58	44.21
			30	105.88	58.82
60	124.17	68.98
			120	170.17	94.54
180	171.02	95.01

Example 8

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 8, which is designated as F-EMR 8.

0.050g of the adsorbent 8 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 12.64% and the adsorption capacity was 3.16mg/g in this case.

0.050g of the adsorbent 8 was put into 50mL of a lead nitrate solution having an initial concentration of 310mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 90.309% and the adsorption capacity was 279.957mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 16. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 93.272% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 6 is 120min when the initial concentration of the adsorbent is 310mg/L of lead ions.

TABLE 16 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	270.16	87.15
5	272.14	87.79
			10	274.42	88.52
20	277.97	89.67
			30	279.96	90.31
60	284.43	91.75
			120	289.14	93.27
180	290.00	93.55

In example 8, the adsorbent had a good lead removal effect and a poor cadmium removal effect. In example 8, the calcination temperature is relatively low, the high-temperature activation degree of the sample is incomplete, the Si-Al-O stable structure in the material cannot be broken, and the CaMg (CO) cannot be reached after the Si-Al-O stable structure is adjusted and deformed₃)₂The reaction conditions with the silicon dioxide in the electrolytic manganese slag, and the electrolytic manganese slag contains calcium sulfate, so the effect on lead is better.

Example 9

(1) mixing 7g of electrolytic manganese slag and 3g of wollastonite, adding 50ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the wollastonite;

(2) standing the mixed solution of the electrolytic manganese slag and the wollastonite for 30min, transferring the mixed solution of the electrolytic manganese slag and the wollastonite into a 50ml centrifuge tube, centrifuging for 10min at 4000r/min, pouring out supernatant liquid, reserving solid, putting the solid into an oven at 60 ℃, drying for 24h, and taking out;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 9, which is designated as F-EMR 9.

The physical structure parameters of EMR, wollastonite and F-EMR9 are as follows:

material	BET(m²g^-1)	Average pore diameter (nm)	Pore volume (cm)³g^-1)
				EMR	3.480	15.877	0.014
Wollastonite	2.963	14.713	0.011
				F-EMR9	5.210	20.268	0.026

As can be seen from FIGS. 18B1 and 18B2(SEM), the shape of F-EMR9 is irregular layer, block structure and loose aggregate stack on the adsorbent, the layer is thin, the vicinity of the thin layer contains precipitation flocs of post-activation reaction, the adsorption is facilitated, a plurality of gaps are formed in the middle of the layer structure, and the channels are smooth.

FIG. 19A is the XRD pattern of wollastonite and FIG. 19B is the XRD pattern of F-EMR9 (obtained in example 9); as shown in the figure, wollastonite mainly comprises a-calcium silicate, b-calcium carbonate, c-silicon dioxide and d-dolomite; and the main components of the F-EMR9 are calcium sulfate, silicon dioxide, ferroferric oxide, manganese dioxide, calcium silicate, magnesium silicate, calcium hydroxide and calcium carbonate.

FIG. 20 is an XPS plot of F-EMR9 (from example 9) before and after Cd (II) and Pb (II) removal; wherein, the chart A is a total spectrogram before and after adsorption, B is a spectrogram for adsorbing Cd, and C is a spectrogram for adsorbing lead;

0.050g of adsorbent 9 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 95.572% and the adsorption capacity was 23.893mg/g in this case. Under the same conditions, the adsorption times were varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 17. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and then slowly increased along with the increase of the adsorption time within 0-30min, 96.412% of adsorption equilibrium is reached within 60min, and the adsorption equilibrium is not broken until 120min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 6 is 60min when the initial concentration of the adsorbent is 25mg/L cadmium ions.

TABLE 17 influence of adsorption time on adsorption Properties of cadmium ions

0.050g of the adsorbent 9 was put into 50mL of a lead nitrate solution having an initial concentration of 600mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 91.324% and the adsorption capacity was 547.945mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 18. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and then slowly increased along with the increase of the adsorption time in 0-20min, 90.511% of adsorption equilibrium is reached in 20min, and the adsorption equilibrium is not broken until 30min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 6 is 20min when the initial concentration of the adsorbent is 600mg/L of lead ions.

TABLE 18 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	175.40	29.23
5	399.40	66.57
			10	479.09	79.85
20	543.07	90.51
			30	547.95	91.32

Example 10

(1) mixing 6g of electrolytic manganese slag and 4g of wollastonite, adding 50ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the wollastonite;

(4) grinding the material obtained in step (3), and sieving with a 100-mesh sieve to obtain adsorbent 10, which is designated as F-EMR10.

0.050g of the adsorbent 10 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 96.02% and the adsorption capacity was 24.005mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 19. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and then slowly increased along with the increase of the adsorption time within 0-30min, 96.72% of adsorption equilibrium is reached within 60min, and the adsorption equilibrium is not broken until 120min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 10 is 60min when adsorbing cadmium ions with the initial concentration of 25 mg/L.

TABLE 19 influence of adsorption time on adsorption Properties of cadmium ions

0.050g of the adsorbent 10 was put into 50mL of a lead nitrate solution having an initial concentration of 120mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 45.971% and the adsorption capacity was 55.165mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 20. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 92.100% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 10 is 120min when the initial concentration of lead ions is 120 mg/L.

TABLE 20 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	31.31	26.09
5	43.32	36.10
			10	44.91	37.43
20	46.25	38.54
			30	55.17	45.97
60	73.76	61.46
			120	110.52	92.10
180	112.60	93.83

Example 11

(1) mixing 13g of electrolytic manganese slag and 7g of wollastonite, adding 100ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the wollastonite;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 11, which is designated as F-EMR 11.

0.050g of the adsorbent 11 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 50.88% and the adsorption capacity was 12.720mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 21. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 96.72% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 11 is 120min when adsorbing cadmium ions with the initial concentration of 25 mg/L.

TABLE 21 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	5.00	20.00
5	9.00	36.00
			10	10.00	40.00
20	11.00	44.00
			30	12.72	50.88
60	18.85	75.40
			120	23.95	95.80
180	24.00	96.00

0.050g of adsorbent 11 was put into 50mL of lead nitrate solution having an initial concentration of 130mg/L, and the solution was adsorbed by stirring at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured by an atomic spectrophotometer, and the result showed that the removal rate was 48.435% and the adsorption capacity was 62.965mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 22. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 95.623% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 11 is 120min when the initial concentration of lead ions is 130 mg/L.

TABLE 22 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	17.90	13.77
5	21.97	16.90
			10	41.73	32.10
20	59.82	46.01
			30	62.97	48.44
60	84.76	65.20
			120	124.31	95.62
180	125.26	96.35

Example 12

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 12, which is designated as F-EMR 12.

0.050g of adsorbent 12 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 59.160% and the adsorption capacity was 14.790mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 23. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 91.200% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 12 is 120min when adsorbing cadmium ions with the initial concentration of 25 mg/L.

TABLE 23 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	0.43	1.72
5	5.15	20.60
			10	10.00	40.00
20	12.55	50.20
			30	14.79	59.16
60	16.44	65.76
			120	22.80	91.20
180	22.90	91.60

0.050g of the adsorbent 12 was put into 50mL of a lead nitrate solution having an initial concentration of 310mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured by an atomic spectrophotometer, and the result showed that the removal rate was 91.456% and the adsorption capacity was 283.515mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 24. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 95.512% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 12 is 120min when the initial concentration of lead ions is 310 mg/L.

TABLE 24 influence of adsorption time on adsorption Properties of lead ions

Comparative example 1

A preparation method of an adsorption material for efficiently removing heavy metal ions in wastewater by utilizing electrolytic manganese slag comprises the following steps:

(1) taking 10g of electrolytic manganese slag, adding 50ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain electrolytic manganese slag liquid;

(2) standing the electrolytic manganese slag liquid for 30min, transferring the electrolytic manganese slag liquid into a 50ml centrifuge tube, centrifuging for 10min at 4000r/min, pouring out supernatant liquid, reserving solid, putting the solid into a 60 ℃ oven, drying for 24h, and taking out;

(3) putting the solid taken out in the step (2) into a muffle furnace, calcining at 800 ℃ for 2h, and cooling to room temperature;

(4) and (4) grinding the substance obtained in the step (3), and sieving the ground substance with a 100-mesh sieve to obtain an adsorbent which is recorded as T-EMR.

0.050g of adsorbent T-EMR was put into 50mL of cadmium nitrate solution having an initial concentration of 100mg/L and stirred at room temperature for adsorption, and after filtration, the content of cadmium ions remaining in the solution was measured by an atomic spectrophotometer, and the results are shown in Table 25.

TABLE 25 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			5	5.00	5.00
10	10.00	10.00
			20	15.00	15.00
30	18.00	18.00
			60	25.64	25.64
120	35.97	35.97
			180	35.73	35.73

0.050g of adsorbent T-EMR was put into 50mL of a lead nitrate solution having an initial concentration of 200mg/L, and the mixture was stirred at room temperature for adsorption, and after filtration, the content of lead ions remaining in the solution was measured by an atomic spectrophotometer, and the results are shown in Table 26.

TABLE 26 influence of adsorption time on adsorption Properties of lead ions

Comparative example 2

A preparation method of an adsorption material for removing heavy metal ions in wastewater based on electrolytic manganese slag-montmorillonite comprises the following steps:

(1) mixing 7g of electrolytic manganese slag and 3g of montmorillonite, adding 50ml of deionized water, stirring by adopting magnetons, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the montmorillonite;

(2) standing the mixed solution of the electrolytic manganese slag and the montmorillonite for 30min, transferring the mixed solution of the electrolytic manganese slag and the montmorillonite into a 50ml centrifuge tube, centrifuging for 10min at 4000r/min, pouring out supernatant liquid, reserving solid, putting the solid into a 60 ℃ oven, drying for 24h, and taking out;

(4) grinding the material obtained in step (3), and sieving with 100 mesh sieve to obtain adsorbent 13, which is designated as F-EMR 13.

FIG. 21A is the XRD pattern of montmorillonite and FIG. 21B is the XRD pattern of F-EMR13 (obtained in comparative example 2); the montmorillonite mainly comprises 1-kaolin and 2-silicon dioxide, and the main components of F-EMR13 are as follows: 1-silicon dioxide, 2-calcium sulfate, 3-manganese dioxide, 4-ferric oxide and 5-calcium silicate.

0.050g of adsorbent 13 was put into 50mL of cadmium nitrate tetrahydrate solution having an initial concentration of 42mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the results showed that the removal rate was 4.929% and the adsorption capacity was 2.070mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, and the data of the removal rate and the adsorption capacity are shown in Table 27.

TABLE 27 influence of adsorption time on adsorption Properties of cadmium ions

0.050g of the adsorbent 13 was put into 50mL of a lead nitrate solution having an initial concentration of 310mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 66.119% and the adsorption capacity was 205.140mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 28. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 67.079% of adsorption equilibrium is reached at 60min, and the adsorption equilibrium is not broken until 120min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 13 is 120min when the initial adsorption concentration is 310mg/L of lead ions.

TABLE 28 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	117.44	37.85
5	184.24	59.38
			10	200.62	64.66
20	204.97	66.06
			30	205.14	66.12
60	208.12	67.08
			120	209.95	67.67

The removal rate of the adsorbent for removing heavy metal ions in the wastewater based on the electrolytic manganese residue-montmorillonite is low. The main components of the montmorillonite are only silicon dioxide, kaolin and the like (see an XRD pattern), and the montmorillonite does not contain carbonate and hydroxyl, so that the silicon dioxide in the electrolytic manganese slag cannot be activated, and the effect is not good.

Comparative example 3

A preparation method of an adsorption material for removing heavy metal ions in wastewater by using electrolytic manganese slag-attapulgite as a basis comprises the following steps:

(1) mixing 7g of electrolytic manganese slag and 3g of attapulgite, adding 50ml of deionized water, stirring by adopting a magneton, and uniformly stirring for 1h to obtain a mixed solution of the electrolytic manganese slag and the attapulgite;

(2) standing the mixed solution of the electrolytic manganese slag and the attapulgite for 30min, transferring the mixed solution of the electrolytic manganese slag and the attapulgite into a 50ml centrifuge tube, centrifuging for 10min at 4000r/min, pouring out supernatant liquid, reserving solid, putting the solid into a 60 ℃ oven, drying for 24h, and taking out;

(4) grinding the material obtained in step (3) and sieving through a 100 mesh sieve to obtain adsorbent 14 designated as F-EMR 14.

FIG. 22A is an XRD pattern of attapulgite, and FIG. 22B is an XRD pattern of F-EMR14 (obtained in comparative example 3); the attapulgite comprises the following main components: the main components of a-silicon dioxide, b-dolomite, c-palygorskite, d-muscovite, e-ferric oxide and F-EMR14 are as follows: a-calcium sulfate, b-silicon dioxide, c-ferric oxide, d-manganese dioxide and e-calcium silicate.

0.050g of adsorbent 14 was put into 50mL of a cadmium nitrate tetrahydrate solution having an initial concentration of 25mg/L, and the solution was stirred and adsorbed at normal temperature for 30 minutes, and after filtration, the content of cadmium ions remaining in the solution was measured with an atomic spectrophotometer, and the result showed that the removal rate was 16.860% and the adsorption capacity was 4.215mg/g in this case. Under the same conditions, the adsorption times were varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes, 120 minutes and 180 minutes, respectively, and the data of the removal rate and the adsorption capacity are shown in Table 29.

TABLE 29 influence of adsorption time on adsorption Properties of cadmium ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	1.24	4.96
5	1.30	6.08
			10	1.52	6.24
20	1.56	10.20
			30	4.22	16.86
60	4.79	19.14
			120	4.79	19.16
180	5.00	20.00

0.050g of the adsorbent 14 was put into 50mL of a lead nitrate solution having an initial concentration of 310mg/L, and the solution was stirred and adsorbed at room temperature for 30 minutes, and after filtration, the content of lead ions remaining in the solution was measured by an atomic spectrophotometer, and as a result, the removal rate was 56.087% and the adsorption capacity was 174.015mg/g in this case. Under the same conditions, the adsorption time was varied to 1 minute, 5 minutes, 10 minutes, 20 minutes, 60 minutes and 120 minutes, and the removal rate and adsorption capacity data obtained are shown in Table 30. It can be seen that the removal rate and the adsorption capacity are greatly increased firstly and slowly increased after 0-60min along with the increase of the adsorption time, 69.152% of adsorption equilibrium is reached in 120min, and the adsorption equilibrium is not broken until 180min, which indicates that the adsorption is stable after the adsorption and no desorption occurs, so that the equilibrium adsorption time of the adsorbent 14 is 120min when the initial concentration of lead ions is 310 mg/L.

TABLE 30 influence of adsorption time on adsorption Properties of lead ions

Adsorption time (min)	Adsorption capacity (mg/g)	Removal Rate (%)
			1	55.09	17.75
5	125.25	40.37
			10	159.90	51.54
20	171.63	55.32
			30	174.02	56.09
60	174.91	56.37
			120	214.55	69.15
180	215.00	69.30

The removal rate of the adsorbent for removing the heavy metal ions in the wastewater based on the electrolytic manganese residue-attapulgite is low. It is known from the XRD pattern of attapulgite that the attapulgite has no hydroxyl ions such as calcium oxide and carbonate which can activate the silica in the electrolytic manganese slag, and thus the adsorption effect is not good.

Claims

1. A preparation method of an adsorbent for efficiently removing heavy metal ions in wastewater based on electrolytic manganese slag is characterized by comprising the following steps:

(1) mixing the electrolytic manganese slag and the ore, and adding the mixture in a ratio of (5-10) mL: 1g of deionized water, and stirring to obtain a mixed solution;

(2) standing the mixed solution obtained in the step (1), centrifuging, pouring out supernatant liquid, reserving solid, drying the solid at the temperature of 60-80 ℃ for 12-36h, and taking out;

(3) putting the solid taken out in the step (2) into a muffle furnace, calcining for 1-3h, and taking out;

(4) grinding the solid taken out in the step (3), and sieving the ground solid with a sieve of 80-120 meshes to obtain an adsorbent;

the ore is selected from at least one of calcite, serpentine and wollastonite.

2. The preparation method according to claim 1, wherein the mass ratio of the electrolytic manganese slag to the ore is (1.5-3): 1.

3. The preparation method according to claim 2, wherein the ore is calcite and the calcining temperature is 600-800 ℃.

4. The preparation method according to claim 2, wherein the ore is serpentine and the calcining temperature is 700-800 ℃.

5. The preparation method according to claim 2, wherein the ore is wollastonite, and the calcining temperature is 600-800 ℃.

6. The preparation method according to claim 3, wherein the ore is calcite, the electrolytic manganese slag and the calcite are calcined at 800 ℃ for 2 hours at a mass ratio of 7: 3.

7. The preparation method according to claim 4, wherein the ore is serpentine, the mass ratio of the electrolytic manganese residue to the serpentine is 7:3, and the ore is calcined at 800 ℃ for 2 h.

8. The preparation method of claim 5, wherein the ore is wollastonite, the mass ratio of the electrolytic manganese slag to the wollastonite is 7:3, and the ore is calcined at 800 ℃ for 2 hours.

9. The method according to any one of claims 1 to 8, wherein the heavy metal ion is Cd (II) and/or Pb (II).

10. The use of the adsorbent obtained by the preparation method of claim 9 for efficiently removing heavy metal ions in wastewater; the use of claim 10, wherein the adsorbent is used for adjusting the pH of a water body to 5-7 before being added to the water body containing heavy metal ions;

the use of claim 10, wherein the adsorbent has an adsorption time of 1 to 360 minutes after addition to the body of water containing heavy metal ions.