CN112978994A - Method for treating stainless steel pickling wastewater and synchronously synthesizing secondary iron mineral - Google Patents
Method for treating stainless steel pickling wastewater and synchronously synthesizing secondary iron mineral Download PDFInfo
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- C02F1/00—Treatment of water, waste water, or sewage
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- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
Abstract
The invention discloses a method for treating stainless steel pickling wastewater and synchronously synthesizing secondary iron minerals, belonging to the field of sewage treatment. The specific process is chemical mineralization combined with alkali neutralization treatment, and the detailed treatment steps are as follows: firstly, pretreating the pickling wastewater, adding an oxidant into a liquid phase after pretreatment for chemical mineralization treatment, collecting generated secondary iron mineral precipitates, and then carrying out alkali neutralization treatment on a solution part to increase the pH value to be neutral. The method can realize the high-efficiency treatment of the stainless steel pickling wastewater, obviously reduce the alkali consumption and the generated toxic neutralization sediment amount, and simultaneously recover the iron bisulfate mineral with excellent adsorption property, thereby being an economic and high-efficiency technique for treating the stainless steel pickling wastewater.
Description
Technical Field
The invention relates to the technical field of sewage treatment, in particular to a treatment process of stainless steel pickling wastewater.
Background
Stainless steel is widely used because of its excellent corrosion resistance. In recent years, with the rapid increase of the consumption of stainless steel, the yield of stainless steel in China is rapidly increased, and the stainless steel is stably kept in the world in 2006, and reaches 1160 ten thousand tons in 2009. In the production of stainless steel, black oxide skin is formed on the surface of the stainless steel after the processes of annealing, normalizing, quenching, welding and the like. The scale skin affects not only appearance quality but also subsequent processing of the product, and therefore, the scale skin is often removed by surface treatment methods such as pickling and polishing before the subsequent processing. The stainless steel pickling process generally comprises the steps of pre-cleaning with sulfuric acid to remove iron scales on the surface, and then performing secondary cleaning with mixed acid of 90-160 g/L nitric acid and 50-60 g/L hydrofluoric acid. The generated acid washing wastewater has high acidity (pH)<1.5) and contains high-concentration toxic and harmful substances such as Fe, Ni, Cr, F and the like. The main hazards of the waste water are that waste water pipelines, reinforced concrete and the like are corroded, and heavy metal ions contained in the waste water seriously pollute water bodies, poison organisms and harm human health. With increasing production (about 1.15 m)3And t), the treatment and disposal of the pickling wastewater become an environmental problem to be solved urgently in the field of stainless steel cleaning.
At present, the mainstream method for treating stainless steel pickling wastewater at home and abroad is an alkali neutralization technology, which is to add an alkaline medicament (flake caustic soda, quicklime and the like) into the wastewater, increase the pH value of the solution and remove metal ions such as Fe, Cr, Ni and the like in a precipitation forming manner. The neutralization precipitation method has simple operation condition and obvious effect. Theoretically, various metal ions in the wastewater can be removed in a precipitation form by adding lime or caustic soda flakes to increase the pH of the wastewater, so that the discharge standard is reached. However, the technology has the problems of large dosage of medicament, low treatment efficiency and high treatment cost in the practical application process; and the generated neutralization sediment has large amount, contains a large amount of toxic metal elements, has low metal taste and is difficult to effectively extract and utilize.
The technical scheme disclosed in the Chinese patent application No. 200710067749.8 proposes that sodium hydroxide replaces lime as a neutralizer, heavy metals in wastewater are independently precipitated, lime is added for defluorination, the separation of metal ions and calcium fluoride is realized, and heavy metal sludge has a remelting condition, but the components are unstable, the nickel chromium amount required to be supplemented is not determined, and the stable operation of stainless steel production is not facilitated. In addition, the process requires a relatively large amount of sodium hydroxide, resulting in high processing costs. The technical scheme disclosed by the Chinese patent application number 201910555141.2 provides a method for treating stainless steel pickling wastewater by using an electrodialysis device, and the current efficiency of the electrodialysis device is improved by bending a membrane and a partition plate, so that the efficient treatment of the stainless steel pickling wastewater is realized. However, in the first step, alkali is added into the pickling wastewater to adjust the pH value to 8.0-8.4, and then the pickling wastewater is filtered after precipitation, so that a large amount of neutralized sediments rich in heavy metals are generated in the process, the treatment is difficult, and secondary pollution to the environment is easy to cause. Chinese patent publication No. CN105060566A discloses a method for treating steel pickling wastewater, which comprises sequentially adding sodium hydroxide and quicklime into wastewater to adjust pH, introducing air, performing solid-liquid separation, and finally adding quartz sand into the supernatant. The method has good effect of removing pollutants in the steel pickling wastewater, but inevitably causes the sludge amount to increase.
The chemical mineralization method is to add an oxidant to promote ferrous ions in the solution to be oxidized and precipitated to form secondary iron minerals, and simultaneously remove other metal ions in the solution in a complexing manner. The inventor applies Chinese patent with publication number CN111620444A in the earlier stage, provides a method for treating acid mine wastewater by biomineralization coupling lime neutralization, and mine wastewater is treated by biomineralization-reduction circulation to increase iron precipitation amount, and is subsequently connected with lime neutralization treatment to achieve complete standard reaching of mine wastewater. The content of metal ions and sulfate radicals in the acid mine wastewater can be greatly reduced through the circular treatment, and the burden of subsequent lime neutralization treatment can be obviously reduced.
In the process of treating the stainless steel pickling wastewater, the requirements of a large amount of neutralizing reagents and the generation of a large amount of heavy metal-containing neutralizing sediments are always difficult to overcome in the field of stainless steel pickling wastewater treatment. Therefore, the invention provides a technology for treating stainless steel pickling wastewater by combining chemical mineralization and caustic soda flake neutralization. The technology can obtain good treatment effect, and can also greatly reduce the consumption of caustic soda flakes and the generation amount of neutralization sediments.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems of large demand of neutralizing agents, large generation of neutralizing sediments and the like in the stainless steel pickling wastewater treatment process in the prior art, the invention provides an environment-friendly, economic and effective method for treating the stainless steel pickling wastewater and synchronously synthesizing secondary iron minerals, and the method has resource recovery efficiency. The treatment method is that firstly, the stainless steel pickling wastewater is treated by a chemical mineralization method, so that a part of metal ions and sulfate ions are precipitated firstly in an acid environment, the alkali addition amount in the subsequent neutralization and precipitation process is saved, and the generation amount of neutralization sediments is reduced. In the treatment process, iron and sulfate radicals are precipitated in the form of secondary hydroxyl ferric sulfate minerals, and the minerals have high-efficiency adsorption performance and high adsorption removal efficiency on trivalent arsenic and hexavalent chromium, are environment function repairing materials and have great environment utilization value.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
the invention provides a stainless steel pickling wastewater treatment method, which comprises the steps of pretreating wastewater to obtain a liquid phase A before neutralizing and precipitating the wastewater, carrying out chemical mineralization treatment on the liquid phase A, and neutralizing and precipitating the solution after the chemical mineralization treatment.
Preferably, the pretreatment of the wastewater comprises: diluting the waste water and/or adding calcium-containing substances into the waste water.
Preferably, the dilution multiple is 3-10, or determined according to the actual iron ion concentration, so that the iron ion concentration in the diluted liquid phase A is 6.2-20.7 g/L.
Preferably, the calcium-containing substance includes CaO or CaCl2Or any combination thereof in any proportion.
Preferably, the amount of the calcium-containing substance added is 80 to 320 g/L.
Preferably, the calcium-containing substance is added, stirred and reacted for 1-2 hours, and then solid-liquid separation is carried out to obtain a liquid phase A.
Preferably, the chemical mineralization treatment is to add an oxidant into the pretreated liquid phase a, and the action of the chemical mineralization treatment is to oxidize ferrous ions in the wastewater into ferric ions, the ferric ions and sulfate ions react together in an acid environment to precipitate minerals, other metal ions in the solution are also partially complexed and precipitated in the precipitation process, solid-liquid separation is performed after mineralization is performed, so as to obtain solid-phase iron oxysulfate minerals and a liquid phase, and the solid-phase iron oxysulfate minerals have good adsorption performance and can be recycled.
Preferably, the oxidizing agent is hydrogen peroxide.
Preferably, the above-mentioned hydrogen peroxide is according to H2O2(ii)/Fe (molar concentration) ═ 0.6 to 1): 1 is added; the hydrogen peroxide can be added once or in multiple times; further, the additive is added for every 30-50 min in multiple times.
Preferably, the pH value of the initial solution of the ore is 1.5-3.5, and the reaction is continuously carried out for 20-40 h under the conditions of the rotating speed of 150-200 r/min and the temperature of 20-28 ℃.
Preferably, the pH of the above-mentioned initial solution is adjusted by adding sodium hydroxide.
Preferably, the minerals obtained after the chemical mineralization are collected, and are washed for 3-5 times by dilute sulfuric acid water with the pH value of 2.0-2.5 to dissolve other impurity ions; and cleaning the substrate for 3-5 times by using pure water, and then drying the substrate.
Preferably, the neutralization precipitation is to add a neutralizing agent caustic soda flake to the liquid phase separated after the oxidant is added so that the pH is 7.0-8.0, and obtain a solid phase neutralization sediment and a liquid phase after solid-liquid separation.
Preferably, the solid phase neutralizes the sediment and the liquid phase, and is discharged after harmless treatment.
The invention also provides a hydroxyl ferric sulfate mineral which is an ore-forming substance generated by chemical ore-forming in the acid washing wastewater treatment process.
The invention also provides application of the iron bisulfate mineral, and the iron bisulfate mineral has good adsorption performance, can adsorb toxic elements in polluted water and has great environmental utilization value.
Preferably, the toxic elements include trivalent arsenic contaminants, hexavalent chromium contaminants, and the like.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron mineral is characterized in that a chemical mineralization method is used for treatment in advance, more than 90% of iron ions and about 50% of sulfate radicals are removed in the mineralization process in a precipitation mode, so that compared with the existing alkali direct neutralization precipitation technology, the required alkali dosage is greatly reduced (by 20% -30%), and the medicament cost is saved; simultaneously, the aim of reducing neutralization sediments is achieved;
(2) compared with the prior art of neutralizing and precipitating flake caustic soda, the novel method for treating the stainless steel pickling wastewater provided by the invention has the advantages that the generated toxic neutralizing sediment amount is reduced by 90-99%, and the treatment cost of subsequent neutralizing sediment can be obviously reduced. In addition, the content of toxic and harmful metals in the neutralized sediments is increased, and the extraction and the reutilization of the metal elements are facilitated;
(3) the secondary hydroxyl ferric sulfate mineral formed in the stainless steel pickling wastewater treatment process provided by the invention has high-efficiency adsorption performance on toxic elements in a water body, is an environment-friendly repair material, and has certain economic benefit.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a picture of the appearance of the mineral obtained by chemical mineralization according to the invention;
FIG. 3 is an XRD diffraction pattern of a mineral obtained by chemical mineralization according to the present invention;
FIG. 4 is an SEM image of a mineral obtained by chemical mineralization in the present invention;
FIG. 5 is a comparison of water quality before and after the stainless steel pickling wastewater is treated by the process of the invention.
Detailed Description
The invention is further described with reference to specific examples.
It is to be noted that, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs; as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
As used herein, the term "about" is used to provide the flexibility and inaccuracy associated with a given term, measure or value. The degree of flexibility for a particular variable can be readily determined by one skilled in the art.
As used herein, at least one of the terms "is intended to be synonymous with one or more of. For example, "at least one of A, B and C" explicitly includes a only, B only, C only, and combinations thereof, respectively.
Concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted to include not only the explicitly recited limit values of 1 to about 4.5, but also include individual numbers (such as 2, 3, 4) and sub-ranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges reciting only one numerical value, such as "less than about 4.5," which should be construed to include all of the aforementioned values and ranges. Moreover, such an interpretation should apply regardless of the breadth of the range or feature being described.
The water sample is sulfuric acid pickling wastewater produced by a certain stainless steel plant, and the water quality conditions are as follows in the following table 1:
TABLE 1 Pickling waste Water quality conditions
Example 1
A method for treating stainless steel pickling wastewater and synchronously synthesizing secondary iron minerals is disclosed, wherein the process is shown as a figure 1, and the method comprises the following steps:
(1) taking 83mL of stainless steel pickling wastewater with pH of 0.04, adding tap water to the wastewater to reach a constant volume of 250mL, namely diluting the wastewater by 3 times. The total Fe concentration is 20.67g/L and the total SO is obtained4 2-The concentration of the liquid phase is 81.00g/L, the total Cr concentration is 5.00g/L, the total Ni concentration is 1.93g/L, the total Mn concentration is 1.40g/L, the total Cu concentration is 0.04g/L and the total Si concentration is 0.02 g/L.
(2) Chemically mineralizing the obtained liquid phase in a shaking table with the rotating speed of 180r/min and the temperature of 28 ℃, wherein the reaction conditions are as follows: 1.1mL of hydrogen peroxide is added every half hour for 6 times; the initial pH of the reaction was 2.5; the reaction time was 24 h. After mineralization, solid-liquid separation is carried out by using a suction filtration device to obtain liquid phase and solid phase minerals. The solid phase was washed 3 times with dilute sulfuric acid (pH2.0) and deionized water, respectively, and then lyophilized for 24h to obtain 17.75g of mineral.
(3) Adding caustic soda flakes into the obtained liquid phase, increasing the pH value of the liquid phase to 7.3-7.5, wherein the adding amount of the caustic soda flakes is 9.99g in the whole experiment process, and performing solid-liquid separation through a suction filtration device after neutralization to obtain a small amount of neutralized sediments and effluent.
The results are shown in table 2: the amount of the neutralized sediment is 0.35g (weight after drying), and the water quality of the effluent is as follows: the pH was 7.34; the total Fe concentration is lower than 0.01g/L and is reduced by 99.98 percent; total SO4 2-The concentration is 19.27g/L, and is reduced by 76.21 percent; the total Cr concentration is lower than 0.01g/L and is reduced by 99.99 percent; the total Ni concentration is 0.31g/L, which is reduced by 84.02%; the total Mn concentration is 0.39g/L, which is reduced by 71.81%; the total Cu concentration is lower than 0.01g/L and is reduced by 99.92 percent; the total Si concentration is lower than 0.01g/L, and is reduced by 86.67%. The method can obviously treat sulfate radical and metal ions in the wastewater.
The picture of the appearance of the mineral synthesized in the step (2) is shown in fig. 2, the mineral is in a reddish brown powder shape and approximately accords with the appearance color of the Schwerk mineral reported in the prior art (Zhou Li, biomineralization, a new method for constructing a novel passive treatment system for acid mine wastewater, chemical bulletin, 2017, 75 (06): 552-559). The XRD pattern is shown in FIG. 3, and the three distinct characteristic peaks (26.3 degrees, 35.2 degrees, 61.3 degrees) on the pattern can indicate that the mineral synthesized by chemical mineralization in the wastewater is Schlemm mineral (Zhuo Zhuang, Guanlin Guo, Xintong Li, et al. effects of hydrogen-peroxide supply on basis of schwertmannite microstructure and chlorine (VI) adsorption performance.2019,367: 520-. As shown in fig. 4, the SEM scanning electron microscope picture of the mineral has dispersed particles, which are blocky, smooth in surface, and large in particle size, and the morphology thereof is different from the morphology (particle aggregation, sphericity, and rough in surface) of the schwann mineral synthesized under the same conditions reported in the prior literature.
The appearance of the effluent finally obtained in the step (3) is compared with that of the original wastewater as shown in fig. 5, so that the stainless steel pickling wastewater is changed into clear yellow brown from original black brown through chemical mineralization and is finally changed into clear transparent colorless through alkali neutralization, and the treatment effect is obvious.
Example 2
A method for treating stainless steel pickling wastewater and synchronously synthesizing secondary iron minerals is disclosed, wherein the process is shown as a figure 1, and the method comprises the following steps:
(1) 250ml of stainless steel pickling waste water with pH 0.04 is taken and then 2 is added0g CaCl2After stirring and reacting for 1 hour, solid-liquid separation was carried out by a centrifuge at 6000g for 10 min. 49.11g of sludge was obtained, and a pretreated liquid phase was obtained;
(2) chemically mineralizing the obtained liquid phase in a shaking table with the rotating speed of 180r/min and the temperature of 28 ℃, wherein the reaction conditions are as follows: adding 20mL of hydrogen peroxide; the initial pH of the reaction was 2.5; the reaction time was 24 h. After mineralization, solid-liquid separation is carried out by a centrifugal machine under the conditions of 6000g and 10min to obtain liquid phase and solid phase minerals. The solid phase was washed 3 times with dilute sulfuric acid (pH2.0) and deionized water each, and then lyophilized for 24h to obtain 64.74g of mineral.
(3) Adding caustic soda flakes into the obtained liquid phase, and increasing the pH value of the liquid phase to 7.3-7.5, wherein the adding amount of the caustic soda flakes in the whole experiment process is 31.60 g. After neutralization, solid-liquid separation is carried out through a suction filtration device, and a small amount of neutralization sediments and effluent are obtained.
The results are shown in table 2: the amount of the neutralized sediment is 0.60g (weight after drying), and the water quality of the effluent is as follows: the pH value is 7.40, the total Fe concentration is 0.04g/L, and the reduction is 99.93 percent; total SO4 2-The concentration is 114.97g/L, and the reduction is 52.69%; the total Cr concentration is lower than 0.01g/L and is reduced by 99.99 percent; the total Ni concentration is 0.58g/L, which is reduced by 89.95%; the total Mn concentration is 1.28g/L, which is reduced by 69.45%; the total Cu concentration is lower than 0.01g/L, which is reduced by 99.62%; the total silicon concentration is lower than 0.01g/L, and is reduced by 98.33 percent. The method can obviously reduce sulfate radicals and metal ions in the wastewater.
The picture of the appearance of the synthetic mineral in the step (2) is shown in fig. 2, the mineral is in a reddish brown powder shape, and the appearance color of the synthetic mineral is consistent with the appearance color of the Schwerk mineral reported in the prior art (Zhou Li. biomineralization: a new method for constructing a novel passive treatment system for acid mine wastewater, chemistry report, 2017, 75 (06): 552-559). The XRD pattern is shown in FIG. 3, and the three distinct characteristic peaks (26.3 degrees, 35.2 degrees, 61.3 degrees) on the pattern can indicate that the mineral synthesized by chemical mineralization in the wastewater is Schlemm mineral (Zhuo Zhuang, Guanlin Guo, Xintong Li, et al. effects of hydrogen-peroxide supply on basis of schwertmannite microstructure and chlorine (VI) adsorption performance.2019,367: 520-. As shown in fig. 4, the SEM scanning electron microscope picture of the mineral shows that the particles are dispersed, are blocky, have smooth surfaces and larger particle diameters, and have a morphology different from the morphology (particle aggregation, sphericity, and rough surface) of the schwann mineral synthesized under the same conditions reported in the prior literature.
The appearance of the effluent finally obtained in the step (3) is compared with that of the original wastewater as shown in fig. 5, so that the stainless steel pickling wastewater is changed into clear yellow brown from original black brown through chemical mineralization and is finally changed into clear transparent colorless through alkali neutralization, and the treatment effect is obvious.
Example 3
In this example, the adsorption capacity of the solid phase minerals obtained in examples 1 and 2 was examined by using trivalent arsenic as an adsorption target.
The mineral obtained in example 1 is denoted as Sch 1, the mineral obtained in example 2 is denoted as Sch 2, and the trivalent arsenic adsorption capacity measurement method is as follows:
(1) accurately weighing 0.010g of Sch 1 and Sch 2 respectively, adding the weighed materials into a 10 mg/L-400 mg/L trivalent arsenic solution, adjusting the pH value of the solution to 7.0, and oscillating the solution in a shaking table at 25 ℃ and 180 r/min. The pH of the solution was monitored every 0.5h and readjusted to 7.0. After 4h, sampling, filtering with a 0.45 mu m filter membrane, and determining the content of trivalent arsenic.
(2) Adsorption isotherms of the two minerals for trivalent arsenic were plotted, and the results are shown in Table 3, and the maximum adsorption capacities of Sch 1 and Sch 2 for trivalent arsenic were 378mg/L and 364mg/L, respectively, as can be fitted by the Langmuir equation. The minerals obtained in the examples 1 and 2 have good trivalent arsenic adsorption performance and obvious environmental utilization value.
Comparative example 1
The comparative example adopts the traditional method for treating the stainless steel pickling wastewater, namely a caustic soda flake neutralization method to carry out a comparative test, and comprises the following steps: taking 250ml of stainless steel pickling wastewater with the pH value of 0.04, and adding sodium hydroxide until the pH value is 7.30-7.50, wherein the dosage of flake caustic soda is 41.00 g. And after neutralization, carrying out solid-liquid separation by a suction filtration device. A large amount of neutralized sediment and effluent are obtained.
The results are shown in Table 2, the amount of the neutralized sludge is 82.02g (dried and weighed), and the effluent quality: pH 7.43, total Fe concentration 3.34g/L, total SO4 2-The concentration is 162.23g/L, and the total Cr is concentratedThe degree is less than 0.01g/L, the total Ni concentration is 0.12g/L, the total Mn concentration is 1.68g/L, the total Cu concentration is less than 0.01g/L, and the total Si concentration is less than 0.01 g/L.
Comparison of comparative example 1 with the experimental data of examples 1 and 2 gives: on the premise of treating equivalent wastewater, when the water body is treated to be equivalent to neutral pH, the addition amount (119.84g/L) of the flake caustic soda required by the process in the example 1 is obviously less than that of a control group (164.00g/L), and the generation amount of the neutralization sediments is also greatly reduced (from 328.08g/L to 4.24 g/L); the addition amount of the flake caustic soda required by the process in the example 2 (126.40g/L) is also obviously smaller than that of the control group (164.00g/L), and the generation amount of the neutralization sediments is also greatly reduced (from 328.08g/L to 2.40 g/L); in addition, the total Fe and the total SO in the effluent water of the example 1 and the example 24 2-The concentration was also significantly lower than the control. Therefore, the invention not only treats total Fe and total SO4 2-The removal effect is better, and the treatment cost of the waste water is greatly saved.
TABLE 2 comparison of treatment effects of stainless steel pickling wastewater
Comparative example 2
Rongwei et al reported that ferrous sulfate heptahydrate had adsorption capacity after chemical mineralization (comparative study of arsenic (III) adsorption performance of Shi mineral and ferrihydrite, proceedings of Nanjing university of agriculture 2020, 43 (6): 1116-1123). in this comparative example, the adsorption capacity of the minerals produced in examples 1 and 2 to trivalent arsenic was studied by comparing the Shi mineral formed by chemical mineralization of ferrous sulfate heptahydrate under the same conditions, and the utility value of the minerals produced in this process was evaluated. The method comprises the following steps:
(1) synthesis of control group minerals: hydrogen peroxide was added in portions (3.3mL/0.5h) to a ferrous sulfate solution with a Fe concentration of 62g/L, adjusting the initial pH of the solution to 2.5. The system is put in a shaking table with the rotating speed of 180r/min and the temperature of 28 ℃ for reaction for 24 h. After the reaction is finished, solid-liquid separation is carried out by a centrifugal machine, the solid phase is washed for 3 times by dilute sulphuric acid (pH2.0) and deionized water respectively,freeze drying for 24h to obtain mineral of control group and recording as SchCK；
(2) The trivalent arsenic adsorption capacity was measured in the same manner as in example 3, namely, 0.010g of Sch was accurately weighedCKAdding the solution into 10 mg/L-400 mg/L trivalent arsenic solution, adjusting the pH value of the solution to 7.0, and oscillating the solution in a shaking table at 25 ℃ and 180 r/min. The pH of the solution was monitored every 0.5h and readjusted to 7.0. Sampling after 4h, and measuring the content of trivalent arsenic after passing through a 0.45-micron filter membrane; the results are shown in Table 3, and Sch can be fitted by Langmuir formulaCKThe maximum adsorption capacity for trivalent arsenic was 339 mg/L.
The results show that the maximum adsorption capacity of the minerals obtained in the examples 1 and 2 on trivalent arsenic is larger than that of the minerals of a control group, namely, the minerals generated in the process of treating the stainless steel pickling wastewater by the method have good trivalent arsenic adsorption performance and obvious environmental utilization value.
TABLE 3 adsorption of trivalent arsenic by synthetic minerals of different treatment systems
Claims (12)
1. The method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron minerals is characterized by comprising the following steps of pretreating the wastewater to obtain a liquid phase A, and treating the liquid phase A, wherein the treatment comprises the following steps:
a) carrying out chemical mineralization treatment on the obtained liquid phase A; b) and (4) carrying out alkali neutralization treatment on the solution after the secondary iron mineral is separated.
2. The method for treating the stainless steel pickling waste water and synchronously synthesizing the secondary iron minerals as claimed in claim 1, wherein the chemical mineralization treatment is to add an oxidant into the liquid phase A.
3. The method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron minerals as claimed in claim 1, wherein the alkali neutralization treatment is to add a neutralizer caustic soda flakes into the solution after the secondary iron minerals are separated so that the pH value of the solution is 7.0-8.0.
4. The method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron mineral as claimed in claim 2, wherein the oxidant is hydrogen peroxide according to H2O2The molar concentration of/Fe is (0.6-1): 1 determination of H2O2The addition amount of the hydrogen peroxide can be one-time addition or multiple-time addition, and the multiple-time addition can be performed once every 30-50 min.
5. The method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron minerals according to claim 4, wherein the pH of an initial solution of the chemical mineralization treatment is 1.5-3.5, and the reaction is continuously carried out for 20-40 h under the conditions of the rotating speed of 150-200 r/min and the temperature of 20-28 ℃.
6. The method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron minerals according to any one of claims 1 to 5, wherein the pretreatment method comprises the following steps of: diluting the waste water and/or adding calcium-containing substances into the waste water.
7. The method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron minerals according to claim 6, wherein when the pretreatment is dilution, the concentration of iron ions in the diluted liquid phase A is 6.2-20.7 g/L.
8. The method for treating wastewater from stainless steel pickling and synchronously synthesizing secondary iron minerals as claimed in claim 6, wherein the calcium-containing substance is CaO and/or CaCl2。
9. The method for treating the stainless steel pickling wastewater and synchronously synthesizing the secondary iron minerals as claimed in claim 8, wherein the addition amount of the calcium-containing substances is 80-320 g/L.
10. An iron hydroxy sulphate mineral formed by chemical mineralisation in a method for the simultaneous treatment of stainless steel pickling waste water and the synthesis of secondary iron minerals according to any one of claims 1 to 9.
11. Use of the iron oxysulfate mineral of claim 10 for adsorbing toxic elements in a contaminated water body.
12. The use according to claim 11, wherein the toxic elements comprise trivalent arsenic contaminants and/or hexavalent chromium contaminants.
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