CN103395912A - Method for removing chromium in acidic wastewater - Google Patents
Method for removing chromium in acidic wastewater Download PDFInfo
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- CN103395912A CN103395912A CN2013103452646A CN201310345264A CN103395912A CN 103395912 A CN103395912 A CN 103395912A CN 2013103452646 A CN2013103452646 A CN 2013103452646A CN 201310345264 A CN201310345264 A CN 201310345264A CN 103395912 A CN103395912 A CN 103395912A
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Abstract
A method for removing chromium in acidic wastewater is provided. A reducing agent and straw biomass charcoal are cooperatively used and added into the chromium-containing acid wastewater, wherein the reducing agent is Na2SO3, and the straw biomass charcoal is peanut straw charcoal prepared at a temperature of 500 DEG C. Through the method, the reducing agent is utilized for reducing hexavalent chromium to trivalent chromium under an acidic condition, and then the straw biomass charcoal is added to remove trivalent chromium in the solution and neutralize the acidity of the solution. On one hand, the biomass charcoal is alkaline and thus can neutralize the acidity of the wastewater and improve a pH value of the wastewater, so that Cr<3+> is easily subjected to a hydrolysis reaction to form precipitation; and on the other hand, in a pH range of 5-7, the biomass charcoal granules promote Cr(III) to hydrolyze to form colloidal flocculation and generate coagulation, and the precipitation velocity of Cr(III) and the velocity of removing the precipitation product from the solution are accelerated.
Description
Technical field
The invention belongs to water, waste water or sewage treatment area, relate to and utilize reductive agent and straw biomass charcoal to be used in conjunction with the chromium of removing in acid waste water.
Background technology
Chromium mainly exists with trivalent (Cr (III)) and two kinds of valence states of sexavalence (Cr (VI)) at occurring in nature, chromic toxicity is chromic 100 times, and when high density, have obvious local irritant effect and corrosive nature, when low concentration, be common sensitizing substance.The method of processing at present chromate waste water is mainly reduction precipitation method, principle is, by reductive agent, chromate is reduced into to trivalent chromium, add again alkali (lime) to make trivalent chromium form insoluble chemical compound, suspension after filtration or centrifugation remove the sedimentable matter of enrichment Cr, reach the purpose that purifies water.Yet due to the impact that is subject to precipitation agent and envrionment conditions, water outlet Cr concentration does not often reach requirement, and (Xiong Bailian, 2010. Southwestern University's journals) need to be for further processing.In addition, the method also exists and consumes chemical materials, the water reuse difficulty, the floor space that produce mud, discharge are large, be not suitable for removing the shortcoming (Liu Juntan prints during 1996. chemical industry) such as trace heavy metal.More about the method for reduction treatment research of chromate at present, and how efficiently to remove Cr
3+Method but seldom, the main or method of alkaline chemical precipitation.Absorption method is considered to have most the sewage purification measure of application potential, because the specific surface area of sorbent material is large, can adsorb and fix the metal ion in waste water, sorbent material has stronger impact resistance to the water yield and change of water quality in addition, and can regenerate after absorption, be difficult for causing the advantages such as secondary pollution (Yan Xu etc., 2010. Liaoning chemical industry).High-efficiency adsorbent commonly used is gac, but its preparation costs dearly.
A large amount of Burning Straws of harvest season cause Air quality severe exacerbation (LuBing etc., 2011. China Environmental Sciences; Yin Cong etc., 2011. China Environmental Sciences), how rationally to process, dispose a large amount of crop materials and caused that people more and more pay close attention to.Crop material has huge specific surface area through biomass charcoal prepared by the anaerobism pyrolysis, and very high cation exchange capacity and the abundant oxygen surface functional group that contains, have very strong adsorptive power and very high loading capacity to heavy metal cation.Biomass charcoal is alkalescence, directly is added to the water and can significantly improves pH value of solution, promotes the precipitation of heavy metal ion on the biomass charcoal surface, and with heavy metal ion, obvious absorption reaction occurs.Simultaneously, the biomass charcoal after processing waste water also is easy to be further processed.Because biomass charcoal is biomass energy, can carry out incineration disposal, reclaim residue, do not produce secondary pollution.Therefore, reductive agent and straw biomass charcoal compounding application are had to the great potential that efficient processing contains the chromic acid wastewater.
Summary of the invention
The technical problem that solves: the purpose of this invention is to provide efficient, a cheap method of processing acidic chromium-containing wastewater, first with reductive agent, Cr (VI) is reduced to Cr (III), add again straw biomass charcoal, the synergy that neutralizes, adsorbs, precipitates and flocculate etc. a plurality of chemical reactions by acidity is removed Cr (III), realizes the efficient removal of chromium in acid waste water and the neutralization of acidity.
Technical scheme:
Remove the method for chromium in acid waste water, reductive agent and straw biomass charcoal are used in conjunction with to add and contain in the chromic acid wastewater, and wherein reductive agent is Na
2SO
3, straw biomass charcoal is the peanut straw charcoal of preparation under 500 ℃.
When chromate concentration in waste water be≤during 1.5mmol/L, Na
2SO
3Add-on is 0.44g/L, biomass charcoal consumption 4.0g/L.
Concrete steps are: by Na
2SO
3Add the acid waste water that contains chromate, and, with after waste water fully mixes 2 hours, add straw biomass charcoal, fully mixed 6 hours, Solid-Liquid Separation is got final product.
Biomass charcoal after treatment of acidic wastewater is air-dry, burning, reclaim residue.
Beneficial effect:
When to containing in the chromic acid wastewater, adding reductive agent Na
2SO
3The time, under acidic conditions, chromate is reduced into Cr (III), continues to add straw biomass charcoal, and because biomass charcoal contains alkaline matter, the solution acidity that neutralized, cause pH value of solution to improve.The biomass charcoal surface is with a large amount of negative charges and oxygen-containing functional group, to positively charged ion Cr
3+Very high loading capacity is arranged.In addition, the raising of pH value of solution has promoted the formation of Cr (III) absorption and precipitation, makes this associating measure, to chromium in solution, very high removal efficiency be arranged, and realizes simultaneously the removal of solution acidity neutralization and pollutent chromium.
For Cr (III) turbid solution in pH5～7 scopes, precipitation is incomplete, and sedimentation speed is slow; But under similar pH, add the flocculation that biomass charcoal has promoted the jelly that Cr (III) hydrolysis forms, and coagulation occurs, not only sedimentation speed is fast, and solid matter is removed fully.
In addition, a large amount of negative charges on biomass charcoal surface and contain the oxygen organo-functional group, to Cr
3+Positively charged ion has very high loading capacity and adsorption strength, the synergy of adding a plurality of chemical reactions such as acidity neutralization after charcoal, absorption, precipitation and flocculation makes this technology, to the chromium in waste water, very high clearance be arranged, and makes wastewater pH be up to state standards (6～9).
Because biomass charcoal is biomass energy, the biomass charcoal of processing after waste water can carry out incineration disposal, reclaims residue, does not produce secondary pollution.
The accompanying drawing explanation
Fig. 1 a is for adding successively Na
2SO
3After biomass charcoal, the clearance of chromium is along with the changing conditions of the increase of initial soln concentration; Fig. 1 b is the changing conditions of the remaining form of chromium in solution along with the increase of initial soln concentration; In figure ▲ and the Cr clearance, * final solution pH, the Cr (VI) that ◇ is residual, the Cr (III) that is residual;
Fig. 2 a is for adding successively Na
2SO
3After biomass charcoal, the clearance of chromium is along with the changing conditions of the increase of initial soln pH; Fig. 2 b is the changing conditions of the remaining form of chromium in solution along with the increase of initial soln pH; In figure ▲ and the Cr clearance, * final solution pH, the Cr (VI) that ◇ is residual, the Cr (III) that is residual;
Fig. 3 is that the different add-ons of biomass charcoal are on the removal effect of chromium and the impact of solution system pH;
In figure ▲ and the Cr clearance, * final solution pH;
Fig. 4 is after biomass charcoal adds, the situation that the content of chromium changed along with the time;
The residual Cr (III) of ■ in figure, the Cr (VI) that is residual, * pH value of solution;
Fig. 5 adds the absorbancy (420nm) of biomass charcoal Cr (III) solution after 1 hour.
Embodiment
Embodiment 1
The anaerobism pyrolysis under 500 ℃ of conditions of peanut stalk is prepared to biomass charcoal.Compound concentration respectively 0.1,0.5,1.0,1.5,3.0mmol/L, and pH is 2 Cr (VI) solution, gets respectively 25mL solution and adds in the 100mL Plastic Bottle, adds successively 0.001,0.004,0.008,0.011,0.022g Na
2SO
3Reductive agent.Mix and placed 24 hours, make reduction reaction complete, then add straw biomass charcoal, isothermal vibration 2h, after standing 12h, filtering separation solid liquid phase, the residual quantity of chromium in mensuration filtrate.
Add the required Na of reduction Cr (VI)
2SO
3After 1.5 times of amount, Cr (VI) is reduced to Cr (III) basically fully, and system pH raises slightly.After continuing to add 0.100g (4g/L) biomass charcoal, system pH is all greater than 7, the Cr (III) that is formed by Cr (VI) reduction issues the reaction of unboiled water solution in high pH condition, biomass charcoal also has certain adsorption to heavy metal ion simultaneously, and the chromium in solution is almost completely removed (Fig. 1 a, 1b).As can be seen here, in chromate concentration is the scope of 0.1～3.0mmol/L, Na
2SO
3With biomass charcoal, be used in conjunction with, can significantly improve the clearance of chromium.
By the identical method of embodiment 1, prepare the peanut straw charcoal.The preparation starting point concentration is Cr (VI) solution of 1.5mmol/L, and initial pH is respectively 1.5,2.0,2.5,3.0,3.5, gets respectively 25mL solution and adds in the 100mL Plastic Bottle, adds 0.011g (0.44g/L) reductive agent Na
2SO
3React after 24 hours, initial pH is 1.5 and 2.0 solution, and Cr (VI) is reduced fully, and initial pH>2.5 solution, Cr (VI) part is reduced, and along with the increase of pH, the Cr that is reduced (VI) measures minimizing.Continue to add the reaction of 0.10g (4g/L) biomass charcoal after 12 hours, initial pH > 2.5 solution, Cr (VI) content does not change before, and Cr (III) is removed fully, and this is due to the adsorption of biomass charcoal and contains alkaline matter and cause.Initial pH is 1.5 solution, Cr (VI), though be reduced to Cr (III) fully, because system pH after reduction is still very low, add the rear system balance pH of 0.100g peanut straw charcoal processing and is about 2.1, biomass charcoal surface negative charge amount is few under this acidic conditions, to Cr
3+Loading capacity and adsorption strength minimum, Cr
3+Precipitating action also not obvious.And initial pH is 2.0 solution, pH value of solution after reduction and biomass charcoal processing > 7, chromium almost all is removed (Fig. 2 a, 2b).Therefore, Cr (VI) reduces and is 2.0 by the initial pH of optimum solution that biomass charcoal is removed.
By the identical method of embodiment 1, prepare the peanut straw charcoal.Preparation starting point concentration 1.5mmol/L Cr (VI) solution, initial pH is 2.0, gets respectively 25mL solution and adds in the 100mL Plastic Bottle, adds 0.011g (0.44g/L) reductive agent Na
2SO
3And after reacting 24 hours, Cr (VI) all can be reduced to Cr (III) fully.Add respectively 0.01,0.05,0.07,0.08,0.10,0.15, after the 0.20g biomass charcoal, Cr (III) removal effect increases along with the increase of the add-on of biomass charcoal, when the biomass charcoal add-on reached 0.100g (4g/L), Cr (III) was removed fully.Along with the increase of biomass charcoal amount, the adsorption site that biomass charcoal provides increases, thereby adsorbs more Cr (III).On the other hand, along with the biomass charcoal addition increases, pH value of solution raises, and when the biomass charcoal addition reached 0.10g (4g/L), pH value of solution reached 7.0, has therefore promoted the synergy of Cr (III) hydrolysis, precipitation and absorption.It is worth mentioning that, when the biomass charcoal add-on was 0.08g, final balanced solution pH was respectively 6.3, and clearance is respectively 93.2%.(Fig. 5) chromium of this moment has formed precipitation, and settling velocity is slow, and the mixing solutions of biomass charcoal and Cr (III) is under this pH, and removal effect is more satisfactory, and settling velocity is fast.
By the identical method of embodiment 1, prepare the peanut straw charcoal.Preparation starting point concentration 1.5mmol/L Cr (VI) solution, initial pH is 2.0, gets respectively 25mL solution and adds in the 100mL Plastic Bottle, adds 0.011g (0.44g/L) reductive agent Na
2SO
3And, after reacting 2 hours, continue to add 0.10g (4g/L) biomass charcoal, after reaction 1min, 5min, 10min, 20min, 30min, 1h, 2h, 4h, 6h, 24h, get measured in solution Cr (III) and Cr (VI) respectively.Result shows, when adding biomass charcoal and reaction times greater than 6 hours, in solution, chromium all is completely removed, and pH value of solution is more than 7.0 (Fig. 4).
Embodiment 5
By the identical method of embodiment 1, prepare the peanut straw charcoal.Preparation starting point concentration 10mmol/L Cr (III) solution, get respectively 25mL solution and add in the 100mL Plastic Bottle, and wherein one group adds 0.10g (4g/L) biomass charcoal, and regulator solution pH is to different value.After pH is stable, shake up standingly, start timing and also observe the sedimentation situation.Figure 5 shows that solution absorbance after sedimentation hour, Cr (III) solution is at pH > 5.0 o'clock, start to form precipitation, along with pH increases muddiness gradually, solution absorbance increases, and during pH6.3, reaches maximum, then with pH, further increase and reduce, illustrate that further raising of pH causes throwing out to strengthen.Add biomass charcoal the throwing out of the colloid that the hydrolysis of Cr (III) solution forms is strengthened, therefore as pH 5.7 the time, solution absorbance is lower than the control treatment that does not add biomass charcoal.Biomass charcoal surface band negative charge, Cr (III) hydrolysate surface band positive charge, both interactions have promoted the flocculation of Cr (III) hydrolysate, and Solid-Liquid Separation is more prone to.
Claims (4)
1. the method for chromium in removal acid waste water, is characterized in that reductive agent and straw biomass charcoal are used in conjunction with to add to contain in the chromic acid wastewater, and wherein reductive agent is Na
2SO
3, straw biomass charcoal is the peanut straw charcoal of preparation under 500 ℃.
2. remove according to claim 1 the method for chromium in acid waste water, it is characterized in that when chromate concentration in waste water is≤1.5 mmol/L Na
2SO
3Add-on is 0.44 g/L, biomass charcoal consumption 4.0 g/L.
3. the method for chromium in described removal acid waste water according to claim 1 and 2, is characterized in that step is: by Na
2SO
3Add the acid waste water that contains chromate, and, with after waste water fully mixes 2 hours, add straw biomass charcoal, fully mixed 6 hours, Solid-Liquid Separation is got final product.
4. the method for chromium in described removal acid waste water according to claim 1 and 2, it is characterized in that the biomass charcoal after treatment of acidic wastewater is air-dry, burn, reclaim residue.
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| CN2013103452646A CN103395912A (en) | 2013-08-09 | 2013-08-09 | Method for removing chromium in acidic wastewater |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103962103A (en) * | 2014-05-11 | 2014-08-06 | 桂林理工大学 | Method for preparing adsorbing material from lotus seed hulls and application of adsorbing material |
| WO2017162013A1 (en) * | 2016-03-25 | 2017-09-28 | 大连理工大学 | Preparation and application method for ion blocking and controlling adsorbent |
| CN109796058A (en) * | 2019-01-03 | 2019-05-24 | 华中科技大学 | A method of Cr VI and organic pollutant combined pollution are administered using charcoal |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101269871A (en) * | 2008-04-23 | 2008-09-24 | 南京大学 | Method for processing chrome wastewater |
| KR20100060259A (en) * | 2008-11-27 | 2010-06-07 | 현대제철 주식회사 | Method for treating acidic waste water |
| CN102351271A (en) * | 2011-07-04 | 2012-02-15 | 中国科学院南京土壤研究所 | Application of straw biomass charcoal in processing electroplating wastewater |
| CN102872803A (en) * | 2012-10-19 | 2013-01-16 | 中国科学院南京土壤研究所 | Aluminum modified straw biomass charcoal as well as preparation method and application thereof on removing arsenic in water body |
-
2013
- 2013-08-09 CN CN2013103452646A patent/CN103395912A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101269871A (en) * | 2008-04-23 | 2008-09-24 | 南京大学 | Method for processing chrome wastewater |
| KR20100060259A (en) * | 2008-11-27 | 2010-06-07 | 현대제철 주식회사 | Method for treating acidic waste water |
| CN102351271A (en) * | 2011-07-04 | 2012-02-15 | 中国科学院南京土壤研究所 | Application of straw biomass charcoal in processing electroplating wastewater |
| CN102872803A (en) * | 2012-10-19 | 2013-01-16 | 中国科学院南京土壤研究所 | Aluminum modified straw biomass charcoal as well as preparation method and application thereof on removing arsenic in water body |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103962103A (en) * | 2014-05-11 | 2014-08-06 | 桂林理工大学 | Method for preparing adsorbing material from lotus seed hulls and application of adsorbing material |
| CN103962103B (en) * | 2014-05-11 | 2016-04-06 | 桂林理工大学 | A kind of utilize lotus seed shell to prepare sorbing material method and application |
| WO2017162013A1 (en) * | 2016-03-25 | 2017-09-28 | 大连理工大学 | Preparation and application method for ion blocking and controlling adsorbent |
| CN109796058A (en) * | 2019-01-03 | 2019-05-24 | 华中科技大学 | A method of Cr VI and organic pollutant combined pollution are administered using charcoal |
| CN109796058B (en) * | 2019-01-03 | 2020-06-02 | 华中科技大学 | Method for treating hexavalent chromium and organic pollutant combined pollution by adopting biochar |
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Application publication date: 20131120 |