CN115805054A - PRB packed column dielectric material taking goethite as raw material - Google Patents
PRB packed column dielectric material taking goethite as raw material Download PDFInfo
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- CN115805054A CN115805054A CN202111076800.8A CN202111076800A CN115805054A CN 115805054 A CN115805054 A CN 115805054A CN 202111076800 A CN202111076800 A CN 202111076800A CN 115805054 A CN115805054 A CN 115805054A
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- 239000002994 raw material Substances 0.000 title claims abstract description 33
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- 229910052595 hematite Inorganic materials 0.000 claims abstract description 81
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Abstract
The invention discloses a Permeable Reactive Barrier (PRB) packed column dielectric material taking goethite as a raw material, which is obtained by calcining goethite at high temperature, has the main component of hematite, can be stably used in a wastewater environment, has obviously improved adsorption performance and large specific surface area, can effectively remove metal elements in heavy metal sewage, and has high water conductivity, high treatment efficiency, long service life and wide application prospect when being used as the PRB dielectric material.
Description
Technical Field
The invention relates to the technical field of wastewater treatment, in particular to an adsorption medium material for treating heavy metal wastewater, and particularly relates to a PRB packed column medium material taking goethite as a raw material.
Background
Toxic heavy metal ions widely exist in soil, sediments, surface water and underground water, and bring serious health threats to the environment and the ecosystem. Hexavalent chromium (Cr (VI)) is a common groundwater contaminant that can accumulate in organisms and pose a serious threat to public and ecological health due to its toxicity and mutagenicity. It is readily soluble in water, strongly mobile in aquatic environments, and is usually present in the form of dichromate or chromate. Prolonged exposure to hexavalent chromium may cause many disorders of human health, such as illness, increased risk of lung cancer, nausea, and may also damage the small capillaries of the kidney and intestines. The mobility, reactivity and bioavailability of chromates in soil environments are affected by the iron oxide mineral adsorption reactions.
In recent years, different porous minerals have been widely used for the adsorption treatment of Cr (VI) due to their micro/mesoporous structure and high Specific Surface Area (SSA). Permeable Reactive Barriers (PRBs) are an in situ remediation technique that uses porous materials as a medium to remove contaminants from groundwater. Various calcined-based adsorbents are widely used due to their low porosity, low density, layered structure, large ion exchange capacity, and good chemical stability. Naturally formed iron (hydr) oxide has a higher reactivity than synthetic iron (hydr) oxide. But still face the problems of low adsorption capacity, short service life, pending improvement of treatment efficiency, etc.
Therefore, the medium materials required in Permeable Reactive Barriers (PRBs) need to be developed more deeply, so that the adsorption medium materials capable of stably treating heavy metal wastewater for a long time are obtained, and the requirements in the current large-scale production are met.
Disclosure of Invention
In order to overcome the problems, the invention provides a PRB packed column medium material taking goethite as a raw material, which is high-adsorption hematite obtained by preferentially growing small crystal faces (110) in the preparation process through high-temperature calcination, and the high-adsorption hematite serving as the medium material of the PRB packed column has the advantages of large specific surface area, greatly improved adsorption performance, capability of effectively removing metal elements in heavy metal sewage, high sewage treatment efficiency and long service life, and can meet the requirements in practical PRBs.
The invention aims at providing a PRB packed column medium material taking goethite as a raw material, which is hematite with excellent adsorption performance obtained by calcining goethite at high temperature. Preferably, the highly adsorbed hematite has an intensity of (110) crystal planes as a percentage of the total intensity of the respective crystal planes of the highly adsorbed hematite as determined by X-ray diffraction to be greater than 8%, preferably greater than 12%, more preferably greater than 16%.
The high-temperature calcination temperature is 260-550 ℃, preferably 290-490 ℃, and more preferably 320-430 ℃.
The specific surface area of the PRB packed column dielectric material taking goethite as the raw material is 80-200m 2 Per g, preferably from 95 to 170m 2 A/g, more preferably 110 to 140m 2 (ii) in terms of/g. The pore volume of the PRB packed column dielectric material taking goethite as the raw material is 0.08-0.45m 3 A/g, preferably of 0.12 to 0.35m 3 A ratio of 0.15 to 0.25 m/g is more preferable 3 /g。
The adsorption capacity of the PRB packed column medium material taking goethite as the raw material is 1.0-4.0mg/g, preferably 1.5-3.5mg/g, and more preferably 2.0-3.0mg/g.
The second aspect of the present invention is to provide a method for preparing the high adsorption hematite, that is, a method for preparing a PRB packed column dielectric material using goethite as a raw material, in which pulverized goethite is calcined under a thermal insulation condition and cooled to obtain the high adsorption hematite.
The crushed goethite has uniform particle size, and the particle size is 12-70 meshes, preferably 16-60 meshes, and more preferably 20-50 meshes.
The goethite content in the goethite is more than 95wt%.
The third aspect of the invention aims to provide a method for treating heavy metal wastewater. The method adopts a PRB packed column for treatment, and the PRB packed column utilizes the high-adsorption hematite as an adsorption reaction material. Preferably, the PRB packed column further comprises an auxiliary material selected from one or more of quartz sand, zeolite, ceramsite and activated carbon, preferably from one or more of quartz sand, zeolite and ceramsite, and more preferably is quartz sand.
The structure of the adsorption reaction material and the auxiliary material in the PRB packed column is an auxiliary material section, an adsorption reaction material section and an auxiliary material section from bottom to top, and preferably, the heights of the sections are the same. And the water outlet of the PRB packed column is higher than the water inlet.
The bulk density of the adsorption reaction material is 1.2-3.2g/cm 3 (ii) a The particle size of the auxiliary material is 2-10 meshes.
The invention provides a use of the PRB packed column medium material taking goethite as a raw material in a PRB packed column for treating wastewater containing heavy metal elements, preferably uranium-containing wastewater, chromium-containing wastewater and lead-containing wastewater, and more preferably chromium-containing wastewater.
The PRB packed column dielectric material taking goethite as the raw material has the beneficial effects that:
(1) The PRB packed column dielectric material in the invention takes natural goethite as a raw material, has wide raw material source, is easy to obtain, is obtained by high-temperature calcination, has simple preparation method, can obtain a uniform PRB packed column dielectric material, and is beneficial to popularization and application.
(2) The PRB packed column medium material mainly comprises iron oxide or iron hydroxide, is environment-friendly, does not generate other pollutants in the wastewater treatment process, and realizes green production and treatment.
(3) According to the invention, after goethite is calcined at high temperature, the (110) crystal face of the obtained hematite preferentially develops, so that the adsorption performance of the hematite is obviously improved, and the hematite has the advantages of good stability, high water conductivity and long service life, and can meet the requirements of PRB packed columns on medium materials.
(4) The PRB packed column medium material is used as an adsorption reaction material to pack the PRB column, so that the treatment effect is good when the chromium-containing wastewater is treated, the wastewater treatment can be continuously and stably carried out, the efficiency is high, the service life is long, and the PRB packed column medium material is beneficial to large-scale popularization and application in PRB.
Drawings
FIG. 1a shows XRD diffractograms of goethite of the present invention and samples-150, 250, 350, 450, 550 prepared in example 1; FIG. 1b shows XRD diffractograms of goethite of the present invention and samples-350-0.5, sample-350-1, sample-350-2, sample-350-3, sample-350-4 prepared in example 1;
FIG. 2 shows the isothermal adsorption curve of-350 vs Cr (VI) for the sample prepared in example 1 of the present invention;
FIG. 3 shows the equilibrium curve of kinetic adsorption of sample 350 produced in example 1 of the present invention, wherein the inset is the quasi-secondary kinetic model curve of adsorption of Cr (VI) by sample 350;
FIG. 4 shows the infrared spectra of goethite and samples-150, sample-250, sample-350, sample-450, and sample-550 made in example 1 of the present invention;
FIG. 5 shows TEM and HRTEM images of raw goethite (a, b, c) of the present invention and sample-350 (d, e, f) made in example 1;
fig. 6 shows the sorption-desorption isotherms and pore size distribution curves of the original goethite of the present invention;
FIG. 7 shows adsorption-desorption isotherms and pore size distribution curves of sample 350 prepared in example 1 of the present invention;
FIG. 8 shows that the k 3-weighted k-edge EXAFS spectra of Cr (VI) on sample-350 made in example 1 of the present invention shows that the theoretical curve (solid line) coincides with the experimental curve (sphere);
FIG. 9 shows that the Fourier transform spectrum of Cr (VI) adsorbed 350 of the sample prepared in example 1 of the present invention produces a radial structure function;
FIG. 10 shows a fitted distribution of simulated Cr and goethite Cr adsorption on the (110) plane according to the present invention;
FIG. 11 shows a fitted distribution of simulated Cr adsorption on (110) plane with hematite (b) in accordance with the present invention;
FIG. 12 shows a breakthrough curve measured when 5mg/L Cr (VI) simulant was introduced into the experimental column in Experimental example 8 of the present invention;
FIG. 13 shows the breakthrough curve of 20mg/L Cr (VI) simulant introduced into the experimental column in Experimental example 8.
Detailed Description
The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The features and advantages of the present invention will become more apparent from the description. In which, although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
According to the PRB packed column dielectric material using goethite as the raw material, provided by the invention, the high-adsorption hematite preferentially growing small crystal faces (110) is prepared by calcining goethite at high temperature, and as the dielectric material of the PRB packed column, the high-adsorption hematite has a large specific surface area, greatly improved adsorption performance, capability of effectively removing metal elements in heavy metal sewage, high sewage treatment efficiency and long service life, and can meet the requirements in actual PRB.
The invention provides a PRB packed column medium material taking goethite as a raw material, which is high-adsorption hematite obtained by calcining goethite at high temperature. Preferably, the intensity of the highly adsorbed hematite crystal planes (110) as a percentage of the total intensity of the crystal planes is greater than 8%, preferably greater than 12%, more preferably greater than 16%, as measured by X-ray diffraction.
When the highly adsorbed hematite was measured by X-ray diffraction, it was found that the (110) crystal plane was preferentially oriented, and the grain size calculated from the scherrer equation also showed that the grain size of the (110) crystal plane gradually increased with the rise in the calcination temperature. According to the current research (such as the Environmental Science & Technology,2016,50 (4): 1964), hematite with more exposed (110) crystal face is more beneficial to the absorption of hexavalent chromium in water.
Natural hematite from different sources or hematite synthesized by different methods have different exposed crystal faces, and pure hematite crystals mainly expose crystal faces (101), (112), (110) and (104), so that hydroxyl positions are distributed differently, and the difference of the adsorption capacity of the pure hematite crystals to pollutants is larger. Compared with the existing hematite with the exposed (110) crystal face, the hematite preparation method is simple and convenient, has low cost and is convenient for large-scale popularization in practical engineering.
Naturally formed iron oxides or hydroxides have a higher reactivity than synthetic iron oxides or hydroxides. The natural goethite is calcined at different temperatures and then thermally decomposed, a large number of pores are generated after dehydration, and the goethite becomes hematite at high temperature. This significantly improves its surface area and adsorption sites. Under the calcining condition of the invention, the specific surface area is greatly improved, and the removal effect is obviously improved.
The high temperature calcination temperature is 260 to 550 ℃, preferably 290 to 490 ℃, more preferably 320 to 430 ℃, e.g. 350 ℃. In the invention, the calcination temperature directly influences the crystal, internal structure and performance change of the product, when the temperature is lower than 260 ℃, goethite is difficult to be transformed into hematite, and when the temperature is higher than 550 ℃, crystal grains are coarsened, the specific surface area is sharply reduced, and the adsorption performance is reduced.
The high adsorption hematite fills the PRB wall alone or together with other auxiliary materials. The auxiliary material is selected from one or more of quartz sand, zeolite, ceramsite and activated carbon, preferably selected from one or more of quartz sand, zeolite and ceramsite, and more preferably quartz sand.
The specific surface area of the PRB packed column medium material taking goethite as the raw material is 80-200m 2 Per g, preferably from 95 to 170m 2 A/g, more preferably 110 to 140m 2 (ii) in terms of/g. The pore volume of the PRB packed column dielectric material taking goethite as the raw material is 0.08-0.45m 3 A/g, preferably of 0.12 to 0.35m 3 A ratio of 0.15 to 0.25 m/g is more preferable 3 (ii) in terms of/g. According to the invention, on the premise of ensuring the mechanical properties such as the strength of the adsorption material, the specific surface area and the pore volume of the PRB packed column medium material are effectively improved, and the adsorption sites are remarkably increased, so that the comprehensive performance of the medium material when used for the PRB packed column is improved.
The adsorption capacity of the PRB packed column medium material taking goethite as the raw material is 1.0-4.0mg/g, preferably 1.5-3.5mg/g, and more preferably 2.0-3.0mg/g. Compared with the existing adsorbing material taking iron oxide as a main component, the PRB packed column medium material provided by the invention has larger adsorption capacity, can effectively ensure the stable and effective work of the PRB wall, further reduces the content of heavy metal elements in wastewater, particularly greatly reduces the content of hexavalent chromium ions, and realizes an excellent treatment effect.
The water conductivity of the PRB packed column dielectric material taking goethite as the raw material is 1.4-6.5cm/h, preferably 2.2-5.5cm/h, and more preferably 3-4.5cm/h. The PRB packed column medium material provided by the invention has high water conductivity, and can remarkably improve the sewage treatment efficiency and treatment capacity while improving the sewage treatment effect, thereby meeting the requirements of practical application.
In a preferred embodiment of the invention, when the PRB packed column medium material taking goethite as the raw material is used, the pH value of the wastewater to be treated is 2-9, preferably 5.5-8.5, more preferably 6-8, such as 6.8-7.2. In the invention, the material has good adsorption performance under the acidic condition to the weak alkaline condition, and is more favorable for promoting the adsorption process under the acidic condition.
The second aspect of the invention also provides a preparation method of the high-adsorption hematite, namely a preparation method of a PRB packed column medium material taking goethite as a raw material.
The crushed goethite has uniform particle size, and the particle size is 12-70 meshes, preferably 16-60 meshes, and more preferably 20-50 meshes. When the particle size is too large, the PRB packed column medium material prepared from goethite is high in water conductivity and small in specific surface area, so that the adsorption of heavy metal chromium is incomplete; if the particle size is too small, the reaction is relatively complete and the adsorption effect is good, but the water conductivity of the PRB medium material is greatly reduced, the treatment efficiency is reduced, the PRB medium material is easy to block, the service life is shortened, and the adsorption treatment effect is reduced.
The goethite content in the goethite is more than 95wt%.
The calcination temperature is between 260 and 550 ℃, preferably between 290 and 490 ℃, more preferably between 320 and 430 ℃, for example 350 ℃. In the invention, the calcination temperature directly influences the crystal, internal structure and performance change of the product, when the temperature is lower than 260 ℃, goethite is difficult to be converted into hematite, and when the temperature is higher than 550 ℃, crystal grains are coarsened, the specific surface area is sharply reduced, and the adsorption performance is reduced.
The calcination time is 0.5 to 2.5 hours, preferably 0.8 to 2 hours, and more preferably 1 to 1.5 hours. The calcination time is too long, the grain size grows larger, the surface area is reduced, and the adsorption performance is not favorably improved; the calcination time is too short, the hematite is not completely converted, and the adsorption performance of the obtained PRB packed column medium material is weakened.
And placing the crushed goethite in calcining equipment at room temperature, and heating along with the equipment. The heating rate is 1-18 ℃/min, preferably 3-12 ℃/min, and more preferably 4-6 ℃/min.
According to the invention, the crushed goethite is calcined in the air, and after the calcination is finished, the goethite is naturally cooled along with calcination equipment to obtain the high-adsorption hematite.
The third aspect of the invention also provides a method for treating heavy metal wastewater, such as uranium-containing wastewater, chromium-containing wastewater and lead-containing wastewater, preferably, chromium-containing wastewater. The method adopts a PRB packed column for treatment, and the PRB packed column utilizes the high-adsorption hematite as an adsorption reaction material, namely a PRB packed column medium material taking goethite as a raw material as the adsorption reaction material. Preferably, the PRB packed column further comprises an auxiliary material selected from one or more of quartz sand, zeolite, ceramsite and activated carbon, preferably from one or more of quartz sand, zeolite and ceramsite, and more preferably is quartz sand.
The structure of the adsorption reaction material and the auxiliary material in the PRB packed column is an auxiliary material section, an adsorption reaction material section and an auxiliary material section from bottom to top, and preferably, the heights of the sections are the same. And the water outlet of the PRB packed column is higher than the water inlet.
In a preferred embodiment of the invention, a plurality of adsorption reactant material segments and a plurality of auxiliary material segments are arranged in the PRB packed column.
The bulk density of the adsorption reaction material is 1.2-3.2g/cm 3 Preferably 1.5 to 2.8g/cm 3 More preferably 1.8 to 2.4g/cm 3 . The particle size of the auxiliary material is 2-10 meshes, and preferably 2-5 meshes.
The porosity of the PRB packed column is 30-75%, preferably 40-70%, and more preferably 50-65%. When the PRB packed column is filled with water in a saturated state, the ratio of the volume of the water to the total volume of the packing is porosity.
The flow rate of the wastewater to be treated in the PRB packed column is 0.15-0.9mL/min, preferably 0.25-0.75mL/min, and more preferably 0.35-0.6mL/min.
The invention provides a use of the PRB packed column medium material taking goethite as a raw material in a PRB packed column for treating wastewater containing heavy metal elements, preferably uranium-containing wastewater, chromium-containing wastewater and lead-containing wastewater, and more preferably chromium-containing wastewater.
The concentration of the heavy metal elements in the treated wastewater containing the heavy metal elements is 2-200 mg/L, preferably 5-110 mg/L, and more preferably 5-20 mg/L.
The PRB packed column medium material taking goethite as the raw material is high-adsorption hematite obtained by calcining the goethite at high temperature, under the calcining condition, a crystal face (110) of the PRB packed column medium material develops in the calcining process, the specific surface area is effectively improved, the PRB packed column medium material has good adsorption performance, the maximum adsorption capacity can reach 2.95mg/g in a static test, and a hysteresis factor R can reach 871 in a dynamic test. Therefore, hematite prepared from 12-70-mesh goethite is selected as a PRB column filling medium material, and has high water conductivity, high treatment efficiency, long service life and wide application prospect in the field of PRB medium materials.
Examples
The present invention is further described below by way of specific examples, which are merely exemplary and do not limit the scope of the present invention in any way.
Example 1
Natural goethite collected from Chenzhou Leping area in Hunan province is crushed into 20-50 meshes.
The composition analysis of the raw goethite showed that the goethite content was as high as 95.95% (see experimental example 1 and experimental example 3).
Respectively calcining the crushed goethite in muffle furnaces at the temperatures of 150 ℃, 250 ℃,350, 450 and 550 ℃ for 1h, wherein the calcining atmosphere is air, placing the goethite in the muffle furnaces at room temperature, raising the temperature along with the furnaces, wherein the temperature raising rate is 5 ℃/min, and cooling along with the furnaces after calcining to obtain calcined samples: sample-150, sample-250, sample-350, sample-450, sample-550. XRD analysis is carried out on the calcined sample, and the XRD spectrum is shown in figure 1 a.
As can be seen from fig. 1, when the calcination temperature reached 350 ℃ and above, goethite underwent phase transition to hematite, and the intensity of the (110) crystal plane accounted for 16.1% of the total intensity of each crystal plane. When the temperature was further increased to 550 ℃, it remained hematite, but the grain size was changed, and the relevant data are shown in experimental example 1.
Respectively calcining the crushed goethite in a muffle furnace at 350 ℃ for 0.5h, 1h, 2h, 3h and 4h, wherein the calcining atmosphere is air, placing the goethite in the muffle furnace at room temperature, heating along with the furnace, wherein the heating rate is 5 ℃/min, cooling along with the furnace after calcining, and obtaining a calcined sample: sample-350-0.5, sample-350-1, sample-350-2, sample-350-3, sample-350-4. XRD analysis was performed on the calcined sample, and the XRD spectrum is shown in FIG. 1 b.
Example 2
Mixing 2.8287g K 2 Cr 2 O 7 (analytically pure) was dissolved in 1L of deionized water to prepare a Cr (VI) solution. Diluting the above solution to obtain K 2 Cr 2 O 7 Adjusting the pH value of the Cr (VI) solution to be close to neutral (the pH value is 6.8-7.2) by the Cr (VI) solution with the concentration of 5, 10, 20, 50, 75, 100, 150 and 200mg/L, so that the pH value of the Cr (VI) solution is consistent with the pH value of the environmental water body of the tailing pond.
0.1g of the sample prepared in example 1, 350 and 20mL of the above Cr (VI) solution, respectively, were mixed in a 50 mL centrifuge tube, and the centrifuge tube was placed on a reciprocating shaker and shaken at 150rpm for 24 hours. The supernatant was then centrifuged at 8000rpm for 10 minutes and analyzed for Cr (VI) concentration and the isothermal adsorption curve for hematite sample-350 vs. Cr (VI) was calculated as shown in FIG. 2.
Wherein, under the condition that the pH value is 6.8-7.2, the adsorption capacity of sample-350 to 200mg/L Cr (VI) solution reaches 2.95mg/g.
In addition, in the kinetic experiments, the mixture was shaken on a reciprocal shaker at 150rpm for 0.1, 0.25, 0.5, 1, 2, 4, 8, 12 and 16 hours at an initial Cr (VI) concentration of 200 mg/L. The suspensions were then analyzed for equilibrium Cr (VI) concentrations at these particular times. After measuring the residual Cr (VI) concentration in the solution at a wavelength of 540nm by using 1,5-Diphenylcarbodihydrazide (DPC) method (see the national standard GB/T7467-1987), a kinetic adsorption equilibrium curve is obtained, as shown in FIG. 3. It is shown by figure 3 that the adsorption of Cr (VI) by hematite conforms to the quasi-secondary kinetic model.
Example 3
A column experiment was performed using the hematite sample-350 prepared in example 1. In order to ensure the water permeability, a sample 350 with the particle size of 20-50 meshes is selected as a PRB medium filling material and filled into an experimental column. The diameter of the experimental column is 3.6cm, the total height is 15cm, the quartz sand, the hematite and the quartz sand are filled from bottom to top, the filling heights are 4cm, 5cm and 4cm respectively, the particle size of the quartz sand is 2-3 meshes, and the stacking density of a sample-350 is 2.01g/cm 3 。
The Pore Volume (PV) of the experimental column can be calculated from the following equation:
the porosity (P) of the experimental column can be calculated from the following formula:
wherein P is porosity, PV is pore volume, and ρ is the density of deionized water (g/cm) 3 ) And V is the total volume (cm) of the column charge 3 ). After the experiment column is filled with intact PRB medium filling material and quartz sand, weighing is carried out, and the weight is recorded as m 1 The deionized water was passed through the column from bottom to top by means of a peristaltic pump until complete saturation (i.e. the weight difference between two successive measurements did not change), at which time the mass of the column was recorded as m 2 The total porosity and total pore volume of the experimental column can be calculated from the above equations.
The experimental column is filled with two media, wherein the top and the bottom of the experimental column are quartz with the height of about 4cm and the grain diameter of 2-3 meshes, and the middle is a sample-350 with 20-50 meshes.
The entire column was packed with quartz and m was measured 1 ＝450.22mg，m 2 =513.92mg; filling the experimental column with quartz and hematite in layers to obtain M 1 ＝456.73mg，M 2 ＝528.76mg。
The porosity P of the quartz experimental column is measured by the method 0 And pore volume PV 0 Total porosity P of the experimental column General assembly And total pore volume PV General assembly Calculating the porosity P of hematite 1 And pore volume PV 1 Comprises the following steps:
PV 1 ＝PV general assembly -PV 0
Groundwater flow was simulated based on hematite porosity (porosity referred to herein as hematite porosity), with a flow set at 0.42mL/min. The water conductivity of hematite measured by the falling difference method is 3.46cm/h.
Determination of hydraulic conductivity by the falling method: the basic principle is according to Darcy's law of porous media under the saturated state, and the basic formula is as follows:
wherein q represents the mineral water flux; Δ H represents the total water potential difference; l represents the linear length of the water flow path; ks is saturated hydraulic conductivity, and a variable water head method is adopted in the experiment. Recording hematite fill height L =50mm, fill radius R =18mm, water column radius R =5mm, head H1=60mm at the start of measurement, head H2=50mm at the end of measurement and measurement time Δ t =92s, the saturated hydraulic conductivity is calculated as follows:
the temperature can affect the saturation hydraulic conductivity of the packed column, so the temperature factor needs to be corrected, and the correction factor is K (25) Namely:
K (fact) ＝K·K (25) ＝0.01059*0.906＝0.0096mm/s＝3.46cm/h
Simulating in waste water, with K 2 Cr 2 O 7 The method comprises the following steps of respectively introducing 5mg/L and 20mg/L of simulated wastewater into the mass meter, introducing the simulated wastewater from the experimental column from bottom to top until the effluent concentration reaches the influent concentration, taking one effluent sample every 8 hours, and determining the wastewater concentration.
The results of the dynamic test are shown in Experimental example 8.
Examples of the experiments
Experimental example 1
X-ray diffraction (XRD) tests were conducted on the raw goethite and samples-150, 250, 350, 450, 550, 350-0.5, 350-1, 350-2, 350-3, 350-4 prepared in example 1. In an X-ray powder diffractometer (D8 Advance, bruker, germany), the target was Cu, the incident wavelength λ =1.5406nm, the tube pressure 40kV, the tube flow 100mA, the scanning speed was set at 8 ° (2 θ)/min, the step size was 0.02 ° (2 θ), and the scanning range was 5 ° -90 °. The XRD patterns obtained by the test are shown in figure 1a and figure 1 b.
Compared with the standard XRD spectrogram (JCPDS No. 8-97) of goethite, the raw material goethite used in the invention has higher purity and no other impurity peaks.
The XRD spectra of samples-150 and-250 coincide with goethite, which should be mainly goethite, indicating that goethite does not undergo a transition to hematite when calcined at 250 ℃.
No peak corresponding to goethite is detected in XRD spectrums of the sample-350, the sample-450 and the sample-550, a new characteristic peak appears in the sample and is identified as hematite, and the intensity of a diffraction peak of the sample is increased along with the increase of the temperature. It can be seen from the peak intensity of the standard diffractogram JCPDS No.1-1053 that the (110) crystal face of the hematite obtained develops well after calcination at a temperature of 350 ℃ and above.
It can be found by calculation using the Scherer formula (the specific data are shown in table 1), that the crystal grain size of the (110) crystal plane is much larger than that determined by other crystal planes. It is speculated that hematite formed after calcination may expose (110) crystal planes.
TABLE 1 particle size of sample-350, sample-450, sample-550
In addition, as the calcination time was prolonged, the diffraction peak intensity of the crystal face gradually increased, and hematite grains grew along the c-axis, and the crystallinity was improved, as shown in fig. b.
Experimental example 2
Infrared spectroscopy was performed on the raw goethite and samples-150, 250, 350, 450, 550 prepared in example 1 using a Fourier transform Infrared spectrometer (FT-IR, spectrum 100, perkinElmer, USA) with the samples distributed uniformly over KBr microspheres before testing. The infrared spectrum obtained by the test is shown in FIG. 4.
At 25 deg.C, goethite is in 3112cm -1 Is shown to be in contact with OH - Broadband related to stretching vibration; due to the presence of water molecules, at 1650cm -1 Has a distinct absorption band; at 894 and 799cm -1 The peak is caused by the bending vibration of Fe-O-H in goethite; at 460cm -1 The peak is caused by the symmetric stretching vibration of Fe-O. At 1080cm -1 And 1023cm -1 The band of (A) may be SiO 2 The Si-O bending vibration peak in (1).
The surface of the goethite after calcination shows that hydroxyl groups are coordinated with iron atoms, OH - The stretching vibration is from 3112cm -1 Move to 3380cm -1 (ii) a The water belt is from 1650cm -1 Moved to 1630cm -1 (ii) a 460. 613 and 894cm -1 All the peak positions of (2) disappear, 799cm -1 A peak of (a) is reduced; at 560 and 464cm -1 A new peak position appears, which indicates the generation of hematite.
Sample-150 at 560cm -1 And 464cm -1 The peak intensity was weak, and 560cm appeared in sample-450 and sample-550 -1 And 464cm -1 The peak position of (a).
It can also be shown by infrared spectroscopy that calcination of goethite at 350 deg.C, 450 deg.C, 550 deg.C gives a highly adsorbed hematite.
Experimental example 3
The composition of the raw goethite was determined using X-ray fluorescence spectroscopy (XRF, electron spectroscopy, ARLADVANT X, u.s.). Specific results are shown in table 2.
TABLE 2 analysis of the composition of crude goethite ores
| Composition (A) | Fe 2 O 3 | SiO 2 | MnO | Al 2 O 3 | CaO | MgO | P 2 O 5 | SO 3 | K 2 O |
| Mass fraction% | 95.95 | 2.608 | 0.769 | 0.299 | 0.161 | 0.151 | 0.024 | 0.021 | 0.019 |
According to the XRD pattern of the raw material goethite in the experimental example 1, the iron oxide exists in the form of goethite, and the content is as high as 95.95%. From the XRF test results, the raw goethite also contains elements such as silicon, manganese, aluminum and the like, but the content is very low, and the corresponding characteristic peak is not shown in an XRD spectrogram.
XRF test results show that the goethite contains trace silicon element, which can correspond to characteristic peaks of silicon-oxygen bonds in Fourier transform infrared spectrum results.
Experimental example 4
The raw goethite and the sample-350 prepared in example 1 were subjected to Transmission Electron Microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). TEM images of the raw material goethite (as in fig. 5a, 5b and 5 c) and sample-350 (as in fig. 5d, 5e and 5 f) are shown in fig. 5.
As can be seen from fig. 5a and 5b, goethite as a raw material is arthropod-shaped, needle-shaped, or prism-shaped. HRTEM test chart FIG. 5 (c) shows that the 0.421nm lattice fringe corresponds to the (110) crystal plane of goethite.
The 0.252nm lattice fringe in FIG. 5f corresponds to the (110) crystal plane of sample-350. It can be clearly observed from fig. 5d that sample-350, obtained after calcination at 350 c, maintains the appearance of the raw goethite. This also supports the conclusion that calcination of goethite at high temperatures can preferentially orient the hematite produced, controlling its exposure to specific crystal planes (110).
The numerous slit-shaped micropores are parallel to the elongation direction of the hematite crystallites, which is caused by dehydroxylation of the goethite. That is, the decomposition reaction occurs substantially inside the crystallites, and the size and shape of the crystals are not greatly changed except for the change in pore size.
Experimental example 5
Specific surface area tests were performed on the raw goethite and samples-250, sample-350, sample-450, and sample-550 prepared in example 1. An adsorption-desorption isotherm and a BET specific surface area (Brunauer-Emmet-Teller) were determined using an automatic gas adsorber (Microactive for ASAP 2460, U.S.) using nitrogen as the adsorbate. The adsorption-desorption isotherm test results of the raw goethite are shown in fig. 6, and the adsorption-desorption isotherm test results of sample-350 are shown in fig. 7.
As can be seen from fig. 6, according to the IUPAC classification, adsorption-desorption isotherms of goethite and samples-250, 350, 450 and 550 all belong to the ii adsorption curve, indicating the presence of mesopores in the above samples.
The hysteresis loop of goethite can be classified as H2 type, and the desorption line drops sharply at moderate relative pressure. The corresponding hole of the hysteresis loop is supposed to be a slit-type hole consisting of closely connected parallel plates.
The hysteresis shapes of the samples-250, 350, 450 and 550 are obviously changed, and are H3 type, and no limit adsorption phenomenon exists at high p/p 0. Such isotherms are presumed to be formed by the formation of fissured pores formed by the aggregation of platy particles. This conclusion, which corresponds to the TEM test of sample-350 in experimental example 3, fig. 5, shows that a large number of elongated pores are generated in the highly adsorbed hematite formed after calcination of goethite.
Goethite BET specific surface area of 36.6m 2 Sample 350 has a maximum surface area of 124.4 m/g 2 (g), sample-450 and sample-550 specific surface areas of 115.0 and 114.0m, respectively 2 (ii) in terms of/g. It is shown that as the calcination temperature is increased, the BET specific surface area begins to decrease and the total pore volume follows the same law.
The pore volume of the raw material goethite is 0.033cm 3 Per g, sample 350 pore volume 0.216cm 3 Per g, the pore volume of sample-450 dropped sharply to 0.060cm 3 (ii) in terms of/g. Presumably, at 350 ℃, the surface area of goethite suddenly increased to a maximum, primarily due to dehydroxylation of the goethite. At the calcination temperatures of 450 ℃ and 550 ℃, the hematite grains coarsen and the surface area decreases. It can be seen that the active surface sites are the most at 350 ℃ for 1 hour of calcination (the specific data are shown in Table 3).
TABLE 3 specific surface area and pore characteristics of goethite and its calcine at different temperatures
As can be seen from Table 3, the average pore size of the raw goethite was about 1.8nm, the average pore size of sample-250 increased to 5.0nm, the average pore size of sample-350 was 8.3nm, and the average pore size of sample-450 sharply decreased to 1.8nm. The pore characteristics of the sample did not change significantly when the temperature was subsequently increased to 550 ℃. The material is shown to have mesoporous internal pores, which is consistent with TEM analysis results, when the calcination temperature is lower than 350 ℃, the pore diameter is gradually increased along with the increase of the calcination temperature, and when the calcination temperature reaches 350 ℃, the calcination temperature continues to increase, and the average pore diameter is rapidly reduced.
Therefore, when the calcination temperature of the goethite reaches 350 ℃, the goethite is converted into hematite, a large number of nano-scale slits are generated in the goethite, and the (110) crystal face of the hematite is exposed, so that the adsorption performance of the material is improved. Therefore, the hematite obtained by calcining at 350 ℃ has the best effect of adsorbing Cr (VI) in water.
Experimental example 6
Cr K-edge EXAFS spectra were performed on a hematite sample-350 after adsorbing Cr (VI) using SPring-8 (Super Photon SPring-8) of the Japan synchrotron radiation research institute. The electron energy of the storage ring is about 8.0GeV and the current is about 99.5mA. Incident X-ray energy was scanned over the EXAFS area on the Cr-k side with a Si (111) twin monochromator. The monochromator was calibrated with chromium foil.
In the case of relatively low Cr concentrations, the measurement of the hematite sample reacted with Cr (VI) is carried out in a fluorescence manner, for the compound K 2 Cr 2 O 7 The reference is measured in transmission. The EXAFS data is converted to r-space by fourier transforming the χ (k) function.
The Coordination Number (CN), distance (R) and disorder factor (σ) were optimized using the Artemis program to fit all datasets in R space simultaneously 2 ). The values of the energy shift are based on the best fit of the first shell (Cr-O) and then fixed at these values for higher shell fits. The phase and amplitude functions of the absorber and back diffuser are defined using the FEFF model (see Journal of the American Chemical Society,1991,113 (14): 5135). After inverse transformation and fitting of each peak in the fourier transform spectrum, the entire spectrum is modeled with the same parameters.
After the sample 350 prepared in example 1 was used to adsorb chromium (Cr (VI)), the solid sample after solid-liquid separation was subjected to extended X-ray absorption fine spectroscopy (EXAFS) testing, and experimental data was subjected to fitting processing to analyze the synergistic environment of Cr (VI) adsorbed on hematite.
The Radial Structure Function (RSF) is obtained by fourier transformation of the χ (k) function, where the peak positions correspond to the interatomic distances inside the material. The position of the peak is not corrected for the phase shift and therefore the position is slightly shifted from the actual interatomic distance (see fig. 8 and 9). By inverse transforming the spectrum, it is possible to buildFitting the experimental spectrum by a theoretical model, and obtaining R, CN and sigma on the basis of optimizing the fitting 2 (see Table 4). After determining the parameters of each peak, fitting
Full fourier filtering of χ (k) function to verify local coordination environment (as shown in fig. 9).
According to a fit between theoretical and experimental spectra, the first peak of the Fourier transform curve is approximately composed of 4 oxygen atoms, which are equally distant from the central Cr atom with an average Cr-O bond length of
This is in conjunction with the tetrahedral HCrO 4 - The bond lengths of Cr-O in the alloy are matched.
Table 4.Exafs spectroscopy to determine local coordination environment parameters for chromate adsorption on hematite nanostructures
According to a fit between the theoretical and experimental spectra, the first peak of the Fourier transform curve is approximately composed of 4 oxygen atoms, which are equally spaced from the central Cr atom
The average Cr-O bond length
And tetrahedral HCrO 4 - The Cr-O bond length of the alloy is well matched. The high distance characteristic of the optical fitting provides Fe back scattering, and the average Cr-Fe interatomic distance in hematite after Cr (VI) is adsorbed is
This matches well with the distance between Cr-Fe atoms of the bidentate binuclear chromate complex. Chromate complexes on hematite are highly dependent on their face exposure. Average distance between Cr-Fe atoms of
Indicating that the hematite surface can form a bidentate binuclear chromate complex.
Experimental example 7
The interaction of Cr (VI) iron oxide is not the same in goethite and hematite. The radial distribution of Cr and Fe can be simulated by software. In studying the arrangement of Cr, goethite and hematite, fe stands for iron hydroxide and iron oxide, cr (K) 2 Cr 2 O 7 Central ortho group) represents K 2 Cr 2 O 7 The results are shown in fig. 10 and fig. 11 on the basis. The first goethite is located
The arrangement of Cr is retained
And
the hematite is distributed in
Cr is distributed in
And
indicating that the distance of chromium from goethite is greater than the distance of chromium from hematite. This means that the phase transition produced by calcination strongly affects the location of Cr, and thermal modification makes Cr a shorter distance from hematite, indicating a stronger interaction.
The high-adsorption hematite obtained after the goethite calcination has better adsorption performance on Cr (VI). The invention carries out molecular dynamics simulation on the arrangement of Cr (VI) in the crystal planes of goethite and hematite (110). The results show that Cr (VI) interacts weakly with the (110) crystal plane of goethite. The goethite is calcined and then converted into the high-adsorption hematite, and the adsorption effect of the goethite on the hematite is superior to that of goethite.
Experimental example 8
The column life test was performed using goethite raw ore and sample-350 prepared in example 1.
In the dynamic column experiment, PV represents the size of the pore volume between the particles of the packing medium, and the hysteresis factor R is defined as the effluent volume when the effluent Cr (VI) concentration is equal to 50% of the input concentration, which is a multiple of PV.
The dynamic experimental result of the experimental column filled with goethite shows that the hysteresis factor R of the goethite column is 7, almost no Cr (VI) is reserved, and the adsorption effect on the Cr (VI) is very small. Furthermore, the Cr (VI) concentration of the final effluent after breakthrough testing was about the same as the initial Cr (VI) concentration, indicating that Cr (VI) was not reduced.
The experimental column was packed as in example 2, using the hematite sample-350 prepared in example 1 as the packing medium material for the column. And continuously introducing Cr (VI) with the concentrations of 5mg/L and 20mg/L into the experimental column respectively as simulation liquid, wherein the retention time of the Cr (VI) simulation liquid in the PRB dynamic column is 72min. When the concentration of the Cr (VI) in the effluent is equal to the input concentration, namely the breakthrough point is reached, and then water is introduced into the experimental column. The breakthrough curves obtained from the test are shown in fig. 12 and 13.
When the initial concentration is 5mg/L, the column can be continuously operated for 552h to reach saturation, and the R value is 871; when the initial concentration is 20mg/L, the operation can be continued for 502h, and the R value is 610. After the clear water is introduced, the concentration of Cr (VI) in the effluent of the experimental column is gradually reduced.
In a batch static batch experiment, the contact reaction time of the Cr (VI) simulation solution and the hematite is 24 hours, and the adsorption quantity reaches 2.95mg/g. In the dynamic column experiment, the lower the flow rate and the longer the residence time, the R value can be obviously improved.
The invention has been described in detail with reference to specific embodiments and/or illustrative examples and the accompanying drawings, which, however, should not be construed as limiting the invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.
Claims (10)
1. The PRB packed column medium material is characterized in that the medium material is high-adsorption hematite obtained by calcining goethite at high temperature.
2. The media material of claim 1, wherein the goethite content is greater than 95wt% of the goethite.
3. Dielectric material according to claim 1 or 2, characterized in that the intensity of the highly adsorbed hematite crystal planes (110) is more than 8%, preferably more than 12% of the total intensity of the individual crystal planes, as determined by X-ray diffraction.
4. A media material according to any one of claims 1 to 3, wherein the adsorption capacity of the media material is 1.0-4.0mg/g, preferably 1.5-3.5mg/g.
5. The dielectric material according to any one of claims 1 to 3, wherein when the PRB packed column dielectric material using goethite as a raw material is used, the pH value of wastewater to be treated is 2-9, preferably 5.5-8.5.
6. The method for preparing the PRB packed column medium material taking the goethite as the raw material according to one of claims 1 to 5, wherein the method comprises the steps of calcining the crushed goethite under the condition of heat preservation, and cooling to obtain the high-adsorption hematite.
7. The method of claim 6,
the crushed goethite has uniform particle size, and the particle size is 12-70 meshes, preferably 16-60 meshes, and more preferably 20-50 meshes;
the calcination temperature is 260-550 ℃, preferably 290-490 ℃, and more preferably 320-430 ℃;
the calcination time is 0.5-2.5h.
8. A method for treating heavy metal wastewater, which is characterized in that PRB packed column medium material which takes goethite as raw material according to one of claims 1 to 6 is used as adsorption reaction material;
the PRB packed column also comprises an auxiliary material which is one or more selected from quartz sand, zeolite, ceramsite and activated carbon.
9. The method of claim 8,
the bulk density of the adsorption reaction material is 1.2-3.2g/cm 3 Preferably 1.5 to 2.8g/cm 3 ；
The porosity of the PRB packed column is 30-75%, and preferably 40-70%;
the flow rate of the wastewater to be treated in the PRB packed column is 0.15-0.9mL/min; preferably 0.25-0.75mL/min.
10. Use of a media material according to one of claims 1 to 5 in a PRB packed column for the treatment of wastewater containing heavy metal elements, preferably uranium-, chromium-, lead-containing wastewater, more preferably chromium-containing wastewater.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102849817A (en) * | 2012-08-24 | 2013-01-02 | 武汉工程大学 | Method for separating heavy metals lead and cadmium by using biological adsorbent packed column |
| CN105152267A (en) * | 2015-09-11 | 2015-12-16 | 安徽美自然环境科技有限公司 | Method for deeply removing phosphorus in water by using calcined limonite |
| CN105692853A (en) * | 2016-04-27 | 2016-06-22 | 合肥工业大学 | Method for removing arsenic in water by means of nano hematite |
-
2021
- 2021-09-14 CN CN202111076800.8A patent/CN115805054A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102849817A (en) * | 2012-08-24 | 2013-01-02 | 武汉工程大学 | Method for separating heavy metals lead and cadmium by using biological adsorbent packed column |
| CN105152267A (en) * | 2015-09-11 | 2015-12-16 | 安徽美自然环境科技有限公司 | Method for deeply removing phosphorus in water by using calcined limonite |
| CN105692853A (en) * | 2016-04-27 | 2016-06-22 | 合肥工业大学 | Method for removing arsenic in water by means of nano hematite |
Non-Patent Citations (5)
| Title |
|---|
| 周艺艺等: ""不同主导晶面赤铁矿对Cr(VI)吸附于迁移行为的影响"", 《农业环境科学学报》, pages 1667 - 1674 * |
| 张羽;刘海波;陈平;皮汇钰;陈天虎;: "热处理褐铁矿去除水中的Mn~(2+)", 岩石矿物学杂志, no. 04, pages 169 - 178 * |
| 杨光成: ""孔状赤铁矿粉末吸附剂脱除水中As(V)的研究"", 《中国优秀硕士学位论文全文数据库 工程科技I辑》, pages 027 - 597 * |
| 石书柳等: ""赤铁矿对模拟污水中重金属铬(Ⅵ)离子的吸附及固定化"", 《化工进展》, pages 1949 - 1955 * |
| 邹雪华等: ""热处理针铁矿的结构与色度演化"", 《硅酸盐学报》, pages 669 - 673 * |
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