CN103011478A - Method for treating humic acid chelated heavy metal by photocatalytic redox - Google Patents
Method for treating humic acid chelated heavy metal by photocatalytic redox Download PDFInfo
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- CN103011478A CN103011478A CN201310014817XA CN201310014817A CN103011478A CN 103011478 A CN103011478 A CN 103011478A CN 201310014817X A CN201310014817X A CN 201310014817XA CN 201310014817 A CN201310014817 A CN 201310014817A CN 103011478 A CN103011478 A CN 103011478A
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- heavy metal
- humic acid
- hydrogen peroxide
- acid
- titanium dioxide
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Abstract
The invention discloses a method for treating humic acid chelated heavy metal by photocatalytic redox, which comprises the following steps: (1) under the condition of 25+/-0.2 DEG C, adding hydrochloric acid or sodium hydroxide into a water solution containing humic acid, heavy metal ions and 0-0.5ml/L formic acid to regulate the pH value to 3.5-11, and standing for 12 hours; (2) after continuously introducing nitrogen gas for 5 minutes to evacuate air, adding commercially available oxydol until the concentration reaches 1-5ml/L; and (3) adding titanium dioxide powder until the concentration reaches 0.1-1.5g/L, adsorbing in a dark place for 30 minutes, and turning on an ultraviolet lamp to irradiate for 180 minutes. The method disclosed by the invention is simple to operate, and has the advantages of low cost and high feasibility; and by simulating the pollutant content in mining industry and using the common titanium dioxide catalyst, the heavy metal ions are reduced under mild conditions, thereby providing references for practical application of photocatalytic oxidation of microorganic substances (humic acid and formic acid) and reduction of trace amounts of low-reduction-potential heavy metal ions.
Description
Technical field
The present invention relates to a kind of photocatalytic redox and process the method that the humic acid huge legendary turtle is closed heavy metal, can be applied to the particularly advanced treatment field behind low reduction potential trace metal ion and the mining medicament chelating of natural humus acid and heavy metal ion in the mining industry polluted drinking water source.
Background technology
Humic acid exists as the little organic overwhelming majority of natural water body, and its molecular structure contains a large amount of functional groups such as carboxyl, phenolic hydroxyl group etc., has plurality of heavy metal ion complexation site, and Surfactant etc. also have very strong adsorption.The most adjacent river of industry mining point and establishing causes containing the mining industry waste water of plurality of heavy metal ion and washup medicament with river converges and move downstream.Dissolved Humic Acids is understood heavy metal ion and the organic medicament in the chelating aqueous solution on the one hand in the water, heavy metal ion and organic medicament on the other hand also can chelating river bottom soiol solution have greatly increased the content of downstream water liquid solution attitude heavy metal ion and organic medicament like this.
And should be less than 0.001-0.01mg/L according to total cadmium in " water environment quality standard " water, to run into the water treatment bottleneck and be higher than this scope several times conventional water treatment process, be higher than this standard tens, tens times even higher and the heavy metal that mining industry causes and organic medicament president phase exist and affect heavy metal in water concentration, serious threat downstream city resident's drinking water safety, therefore need more environmental protection, economy, effectively and be fit to the methodological innovation that Raw Drinking Water is processed.
Titanium dioxide with himself stable performance, reaction fast, mild condition, do not have selectivity and do not have secondary pollution and large quantity research and the photocatalyst that gets the nod.Under the irradiation of UV-light, titanium dioxide can excite light induced electron, and that realizes electronics and hole separates the formation electron-hole pair.The hole is met water and is formed the hydroxyl radical free radical that has up to the 2.8eV strong oxidizing property, and the organism of energy oxidation humic acid and absorption thereof destroys the functional groups such as carboxyl, phenolic hydroxyl group the heavy metal ion of chelating is released; Light induced electron has reductibility, and the acceptor that heavy metal ion becomes electronics is reduced into lower valency or metal simple-substance.
Band theory is thought, any material, as long as its redox potential is more negative than semi-conductive valence band current potential (2.8eV, pH=7), and will be by the oxidation of the institute of the hole on the valence band, photocatalysis oxidation reaction just can occur.Oxidizing reaction can be destroyed the keys such as C-C, C-H in the organism, C-N, C-0, N-H, can oxidation most organic pollutants and part inorganic pollutant, even the organism in can the oxidizing bacteria body, generate CO
2And H
2O can also play oxidizing reaction with poisonous inorganics, makes it lose toxicity in asking in short-term.
According to band theory, any metal ion is as long as its reduction potential than semi-conductive conduction band current potential (0.5eV, pH=7) corrigendum, just might and be reduced from conduction band acquisition excitation electron simultaneously.May there be 3 kinds of approach in the photo catalytic reduction metal ion: 1. direct-reduction, it is feasible metal ion on the light induced electron direct-reduction thermodynamics, the redox potential of metal ion can be reduced to the metal ion of corresponding metal simple-substance or lower valency greater than 0.4V; 2. indirect reduction, then the organism (hole trapping agents) that is namely added by the hole initial oxidation comes the reducing metal ion by the intermediate that produces, and perhaps by modification, makes the titanium dioxide interfacial potential that negative moving occur; 3. the oxidation removal metal ion makes it with the high oxidation state stable existence.
In numerous heavy metal ion, there are picture plumbous (Pb), nickel (Ni), the low faint metal ion of thermodynamics motivating force of cadmium (Cd) class reduction potential, can only be by indirect reduction.And cadmium metal (Cd
2+/ Cd) minimum (the Cr of reduction potential (0.403V, pH=7)
3+Except/the Cr, because of Cr
3+Toxicity less), theoretical by the thermokinetics motivating force, if cadmium ion (Cd
2+) can under certain condition, be reduced into and be metal simple-substance or other kenels, then other heavy metal ion also can be reduced into and be simple substance or other forms, thereby reduce the toxicity of these heavy metals.
Summary of the invention
The purpose of this invention is to provide a kind of photocatalytic redox and process the method that the humic acid huge legendary turtle is closed heavy metal.
Thinking of the present invention is: pollutent environmental aspect in the river that the simulation mining industry is polluted, in photocatalytic oxidation reactor, regulate reaction conditions and reactant composition content and ratio, contain the important composition formic acid of natural water body Micropollutants humic acid and beneficiation reagent in the component.In nitrogen atmosphere, add preparation titanium deoxide catalyst and the hydrogen peroxide of certain proportioning, after secretly adsorbing 30min, the unlatching ultraviolet lamp (λ＜387nm), per ten minutes sampling and measuring pollutant loads.Dominant technology of the present invention be have state of nature content organic acid (humic acid and formic acid) in the presence of, add a certain proportion of strong oxidizing property material hydrogen peroxide, with the modifying titanium dioxide mating reaction, make its oxidation-reduction quality embody stronglyer, reaching efficient removal is the purpose of organism and the low reduction potential heavy metal of reduction.
Concrete steps are:
(1) under 25 ± 0.2 ℃ of conditions, adding hydrochloric acid or sodium hydroxide adjusting pH value in the water that contains humic acid, heavy metal ion and 0-0.5ml/L formic acid is 3.5,7 or 11, leaves standstill 12 hours.
(2) continue to expose to the sun behind the nitrogen 5min exhausted air in step (1) obtained aqueous solution, adding hydrogen peroxide, to make hydrogen peroxide concentration be 1-5ml/L.
(3) adding titania powder in step (2) obtained aqueous solution, to make titanium dioxide concentration be 0.1-1.5g/L, secretly adsorb 30min after, open ultra violet lamp 180min; Add per ten minutes sampling and measuring pollutant loads of beginning at titanium dioxide, and when 30min and reaction end, get the air-dry preservation of solid-like.
Described hydrogen peroxide is commercially available hydrogen peroxide.
Characteristics of the present invention:
(1) adopts cheap modified catalyst, select the metal ion cadmium ion of the low high toxicity of reduction potential as research object, the contaminate environment of simulation mining industry, utilize the natural water body humic acid can the chelating heavy metal ion and the characteristics of organic medicament, the heavy metal ion that oxidation humic acid and organic medicament and the humic acid that reduces simultaneously discharge in the presence of ultraviolet lamp and catalyzer is of practical significance to solution and the industrialization low cost movement of an existing water technology difficult problem; (2) under the condition of a certain amount of hydrogen peroxide of proportioning, realize the heavy metal cadmium of the low reduction potential of reduction; (3) methyl viologen colour developing experiment, transmission electron microscope (TEM) and high resolution XPS can both prove that the valence state of cadmium metal ion and form have obtained change; (4) the two single improving a lot of efficiency ratio of heavy metal ion reduction and oxidation operation has been played the effect of mutually promoting.
The inventive method is simple to operate, cost is lower, feasibility is large, simulation mining industry pollutant load, use modified catalyst, reducing heavy metal ion ion under mild conditions provides reference for the little organic substance humic acid of photochemical catalytic oxidation and formic acid reduce the practical application of low reduction potential trace heavy metal ion simultaneously.
Embodiment
Embodiment:
(1) the abundant chelating of simulation humic acid and heavy metal and formate: under 25 ± 0.2 ℃ of conditions, add respectively in ultrapure water to 3 reactor volume 4L; In 3 reactors, add respectively humic acid solution, formic acid solution and cadmium-ion solution, making humic acid solubility according to river tap water environment is 10mg/L, formic acid solubility is 0.3ml/L, concentration of cadmium ions is 200 μ g/L, add the salt acid for adjusting pH value and be respectively 3.5,7 and 11, left standstill 12 hours, and allowed the sufficient Adsorption of Heavy Metal Ions of humic acid and formate.
(2) aeration is discharged dissolved oxygen: in (1) 3 reactor of step, expose to the sun respectively nitrogen and continue 5min after, adding commercially available hydrogen peroxide, to make hydrogen peroxide concentration be 3ml/L.
(3) ultraviolet luminous energy and catalyzer acting in conjunction: adding respectively titania powder in (2) 3 reactors of step, to make titanium dioxide concentration be 0.9g/L, secretly adsorbs 30min, opens ultra violet lamp 180min; Per ten minutes sampling and measuring pollutant loads after titanium dioxide adds, and when 30min and reaction end, get the air-dry preservation of solid-like.
The reduction removal effect that detects cadmium ion in the solution sees the following form:
| Clearance (%) | pH=3.5 | pH=7 | pH=11 |
| Dark reaction during 30min | 2.4 | 28.7 | 63.8 |
| Photochemical catalysis during 180min | 22.3 | 45.1 | 91.6 |
Stop laggard row methyl viologen colour developing experiment in reaction, its principle is Cd
0+ 2MV
2+(white) → Cd
2++ 2MV
+(blue); After two hours, the methyl viologen solution of finding to be added in the solid particulate matter that separates after the reaction under the illumination condition becomes blueness by white, illustrates to exist cadmium ion to be reduced into the fact into metal simple-substance.
Titanium elements mapping graph and the cadmium element mapping graph of transmission electron microscope (TEM) show that cadmium is dispersed in the titanium dioxide solid surface, illustrate that light-catalyzed reaction occurs at titanium dioxide surface.
High resolution XPS shows that 405.46eV(CdO has appearred in the solid after the photoresponse), 405.50eV(Cd
3d
5/2) Energy value, solid presented 405.73eV(Cd when dark reaction finished
2+) Energy value, proved that light-catalyzed reaction just can make cadmium ion valence state or form change.
Simultaneously, be 7 at pH, formic acid concn is at 0.3ml/L, hydrogen peroxide content is 3ml/L, when content of titanium dioxide is 0.9g/L, contrast does not add the cadmium metal ion, and the clearance that has added humic acid, formic acid and the TOC of cadmium-ion solution brings up to 89.7%, 34.2% and 63.6% by original 71.3%, 15.1% and 42.7%; Be 3ml/L at hydrogen peroxide content, when content of titanium dioxide is 0.9g/L, selecting concentration is the cadmium ion of 200 μ g/L, it is that 11 o'clock maximum material removal rate is 77.5% at pH, be 91.6% and the photochemical catalysis result behind the adding humic acid is the hydrolysate rate, the existence that humic acid is described has promoted the final removal of cadmium ion.Illustrate that efficient was greatly improved when oxidation of organic compounds and reducing heavy metal carried out than the two single carrying out simultaneously.
Claims (1)
1. a photocatalytic redox is processed the method that the humic acid huge legendary turtle is closed heavy metal, it is characterized in that concrete steps are:
(1) under 25 ± 0.2 ℃ of conditions, adding hydrochloric acid or sodium hydroxide adjusting pH value in containing humic acid, heavy metal ion and 0-0.5ml/L aqueous formic acid is 3.5,7 or 11, leaves standstill 12 hours;
(2) continue to expose to the sun behind the nitrogen 5min exhausted air in step (1) gained solution water, adding hydrogen peroxide, to make hydrogen peroxide concentration be 1-5ml/L;
(3) adding titania powder in step (2) gained water, to make titanium dioxide concentration be 0.1-1.5g/L, secretly adsorb 30min after, open ultra violet lamp 180min;
Described hydrogen peroxide is commercially available hydrogen peroxide.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104944511A (en) * | 2015-05-27 | 2015-09-30 | 北京大学 | Method and device for removing heavy metal ions in wastewater by virtue of photoelectrocatalysis |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102531095A (en) * | 2010-12-14 | 2012-07-04 | 佳龙科技工程股份有限公司 | Method for removing heavy metal in waste liquid |
| CN202542910U (en) * | 2011-12-27 | 2012-11-21 | 南京林业大学 | Multifunctional water treating device for removing heavy metals and organic pollution |
-
2013
- 2013-01-16 CN CN201310014817XA patent/CN103011478A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102531095A (en) * | 2010-12-14 | 2012-07-04 | 佳龙科技工程股份有限公司 | Method for removing heavy metal in waste liquid |
| CN202542910U (en) * | 2011-12-27 | 2012-11-21 | 南京林业大学 | Multifunctional water treating device for removing heavy metals and organic pollution |
Non-Patent Citations (4)
| Title |
|---|
| 《Electrochemistry Communications》 20000731 C.R. Chenthamarakshan等 Photocatalytic reduction of divalent zinc and cadmium ions in aqueous TiO2 suspensions: an interfacial induced adsorption-reduction pathway mediated by formate ions 第2卷, 第7期 * |
| C.R. CHENTHAMARAKSHAN等: "Photocatalytic reduction of divalent zinc and cadmium ions in aqueous TiO2 suspensions: an interfacial induced adsorption–reduction pathway mediated by formate ions", 《ELECTROCHEMISTRY COMMUNICATIONS》 * |
| JAE-KYU YANG等: "Removal of Cr(VI) and humic acid by using TiO2 photocatalysis", 《CHEMOSPHERE》 * |
| 林龙利等: "TiO2光催化同步去除水体中重金属和有机物研究进展", 《科技导报》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104944511A (en) * | 2015-05-27 | 2015-09-30 | 北京大学 | Method and device for removing heavy metal ions in wastewater by virtue of photoelectrocatalysis |
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Application publication date: 20130403 |