CN104109877A - Electrochemical oxidation method for oxidizing iodide ion in chlor-alkali raw material brine into iodine - Google Patents
Electrochemical oxidation method for oxidizing iodide ion in chlor-alkali raw material brine into iodine Download PDFInfo
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- CN104109877A CN104109877A CN201410264123.6A CN201410264123A CN104109877A CN 104109877 A CN104109877 A CN 104109877A CN 201410264123 A CN201410264123 A CN 201410264123A CN 104109877 A CN104109877 A CN 104109877A
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Abstract
The invention relates to an electrochemical oxidation method for oxidizing iodide ion in chlor-alkali raw material brine into iodine. Different electrochemical reactions of a platinum electrode occur at a certain degree of acidity in different potential sections. When a low polarization potential is selected, the electrochemical reaction on the platinum electrode is shown in the specification and I<-> is oxidized into I2. The pH of the chlor-alkali raw material brine is adjusted by utilization of hydrochloric acid to 2-6. Treatment is performed in a polarization potential section of 0.10-0.60 V for 10-50 min, and the electrochemical oxidation method oxidizes the iodide ion in the chlor-alkali raw material brine into the iodine. Compared with iodide ion oxidation by adding additives in the prior art, the electrochemical oxidation method achieves iodide ion conversion into the iodine by controlling different electrochemical reactions in different electric current densities, is a physical method, is free of introduction of other chemical components, and avoids possible influences caused by adding the additives on ionic membranes.
Description
Technical field
The present invention relates to the method for oxidation of iodide ion in a kind of chlor-alkali raw material salt solution, is mainly to adopt electrochemical process that iodide ion is oxidized to elemental iodine.
Background technology
Singularity due to ionic membrane alkaline, salt solution is outer row never, make the continuous enrichment of foreign ion and surpass the ability to bear of ionic membrane, in recent years, particularly the enrichment of iodide ion has been a great concern the impact of ionic membrane, because iodide ion contained in salt solution can generate the great Na of molecular weight in electrolytic process
3h
2iO
6, Ba
3h
4(IO
6)
2, will plug ion membrane channel, hinder sodium ion and pass through, reduce current efficiency, service life of ion-exchange membrane is shortened.And ionic membrane is expensive, as frequent replacing ionic membrane, to the interests of factory, be totally unfavorable.Therefore, the iodide ion in chlor-alkali water is reduced to elemental iodine and is the most direct and cost-effective measure by its removal.
At present, not yet ripe to the removal research of iodide ion in salt solution both at home and abroad, lack theoretical basis, apart from industrial applications, also have a segment distance.The method that conventional iodide ion is oxidized to elemental iodine mainly contains following several:
1) oxygenant oxidation style
As " related a kind of by I in CN18072452A " in ion film caustic soda raw material, Trace Iodine removes " in Chinese patent
-be oxidized to I
2method, this I
-the technical scheme of oxidation style is: in chlor-alkali brine treatment groove, squeeze into concentrated hydrochloric acid acidifying, make pH=2～6, stir 5～15min, then add oxygenant, being chosen as of oxygenant: one or more in hydrogen peroxide, clorox, iron trichloride, sodium chlorate, chlorine.The oxygenant adding is by the I in chlor-alkali salt solution
-be oxidized to I
2, then by inorganic adsorbent, adsorb I
2remove.
Shortcoming of the present invention: the iodide ion oxygenant adding may have residual in chlor-alkali salt solution, has been equivalent to introduce new impurity, may exert an influence to ionic membrane.In addition, the long reaction time of this oxidation style, operating process is loaded down with trivial details, and efficiency is lower.
2) Ozonation
The related basic skills of ozone oxidation iodide ion is: application redox principle, utilize the strong oxidizing property of ozone, the iodide ion of the chlor-alkali raw material salt solution of not electrolysis or the circulation light salt brine after electrolytic tank electrolysis operation is oxidized to elemental iodine, reaction is carried out under acidic conditions, and reaction equation is:
O
3+ 2I
-+ H
2o==O
2+ 2OH
-+ I
2, ozone gas is in iodine oxide ion, also as the swept-off gases of elemental iodine.
The advantage of Ozonation is: when a kind of iodide ion oxygenant is provided, ozone, also as the swept-off gases of elemental iodine, makes elemental iodine enter sooner absorption phase, has improved the efficiency of whole technique.Meanwhile, ozone is during as oxygenant, and the solubleness in water is low, can not introduce new impurity to chlor-alkali salt solution.The shortcoming of this method is: because ozone itself is insoluble in water, therefore Ozonation is not suitable for removing or obtain the chlor-alkali salt solution that iodide ion concentration is very low.
Summary of the invention
The object of the present invention is to provide a kind of method that is oxidized iodide ion in chlor-alkali raw material salt water.
The technical scheme that the present invention realizes its object is as follows: under acidic conditions, adopt electrochemical oxidation process that the iodide ion in chlor-alkali salt solution is oxidized to elemental iodine, then by its Adsorption.Its technological process is: the salt solution of certain temperature and acidity is squeezed into bittern groove, after pretreatment, according to the electrochemical reaction behavior of the interval corresponding electrolysis time of different potentials on platinum electrode (being i～t method), selected electric potential is interval, salt solution is carried out to electrolysis, solution is stirred simultaneously, electrolysis temperature is 40 ℃, reaction times is 10min～50min, electrolytic anode generation electrolytic reaction: 2I
--2e
-→ I
2, iodide ion is oxidized to elemental iodine, then can adopt air scavenging method or adopt the inorganic adsorbent absorption methods such as gac, molecular sieve, carclazyte, diatomite to be removed.
The method relating to of the present invention is:
Adopt the electrochemical reaction mechanism of cyclic voltammetry research iodide ion in ionogen.In acidic medium, the electrochemical reaction behavior difference of iodide ion on certain acidity, platinum electrode different potentials interval, (is less than 0.60V (vsHg/Hg when polarized potential is lower
2sO
4)) time, on platinum electrode, there is 2I in iodide ion
--2e → I
2electro-oxidation reaction, removes iodine through air scavenging method or inorganic adsorbent absorption method after oxidation.
Advantage of the present invention and positively effect are:
1, than passed through the method for oxygenant iodine oxide ion in the past, electrochemical process can not brought new composition to chlor-alkali raw material salt solution, has got rid of the impact on ionic membrane because adding oxygenant to bring.
2, the content of iodine in chlor-alkali raw material salt solution (can be pressed to I
-calculating) requirement that is reduced to ionic membrane method production caustic soda is even below 0.05mg/L.
3, than in the past except iodine method, electrochemical process except the required reaction times of iodine few, efficiency is higher,
4, the present invention removes the method for iodine in chlor-alkali salt solution, can not cause secondary pollution, simple to operate to environment, easily realizes the advantages such as automatization.
5, method of the present invention can be used for industrial large-scale operation application.
Accompanying drawing explanation
Accompanying drawing is the part of production schema of chloralkali process
Below in conjunction with drawings and Examples, the technical program is described further.
In figure: 1. secondary refined brine storage tank, 2. light salt brine storage tank, 3. iodide ion oxidization electrolysis groove, 4. active carbon adsorber, 5. chlor-alkali production technique electrolyzer, 6. valve, 7,11,13,15 under meters, 8,10,12,14 acid proof pump, 9. agitator motors
Embodiment
Below by specific embodiment, the invention will be further described, but do not limit the present invention.
1) test of platinum Electrode and check:
Platinum Electrode carries out the strict processing such as mechanical polishing, electrochemical degreasing, nitric acid dousing before test, is then placed in 0.50mol/L sulfuric acid and carries out cyclic voltammetry.In test, adopted three-electrode system, wherein Electrode and supporting electrode are platinum electrode, and reference electrode is Hg/Hg
2sO
4electrode (concentration of sulfuric acid is 1.00mol/L).Current potential in experiment is with three-electrode system, and the current potential of controlling working electrode with reference electrode keeps constant.
2) after chlor-alkali salt solution, secondary refining (1) refining through one-level, mix with the light salt brine producing in chloralkali process (2), by pump (8), through under meter, squeezed in iodide ion oxidization electrolysis groove (3), open stirrer (9) stirs simultaneously, electrolysis under constantly stirring, reaction 10～50min then squeezes into active carbon adsorber (4) adsorption treatment 10～50min by pump (10) after under meter (11) metering.Process salt solution later, its iodide ion concentration reaches the requirement (≤0.20mg/L) that ionic membrane method is produced caustic soda, this salt solution is squeezed into chlor-alkali production electrolyzer by pump (12) through under meter (13) again, and the light salt brine produce producing is continued to be back in light salt brine storage tank (2) through under meter (15) by pump (14) and recycles.
Embodiment 1
Factory's chlor-alkali raw material salt solution carries out electrolytic oxidation reaction in iodide ion oxidization electrolysis groove, and polarized potential value is 0.20v, stirring velocity 80rpm, reaction 20min.Chlor-alkali salt solution after oxidization electrolysis is through charcoal absorption in adsorber, and it is 10～50min that adsorption temp maintains 50 ℃, adsorption time.In salt solution, the content of iodine is down to 0.19mg/L by the 1.0mg/L before processing.
Iodine content analysis adopts water iodine rapid quantitative detection reagent box (production of Shanghai Hu Feng Chemical Co., Ltd.), lower same.
Embodiment 2
Factory's chlor-alkali raw material salt solution carries out electrolytic oxidation reaction in iodide ion oxidization electrolysis groove, and polarized potential value is 0.20v, stirring velocity 80rpm, reaction 40min.Chlor-alkali salt solution after oxidization electrolysis is through charcoal absorption in adsorber, and it is 10～50min that adsorption temp maintains 50 ℃, adsorption time.In salt solution, the content of iodine is down to 0.14mg/L by the 1.0mg/L before processing.
Embodiment 3
Factory's chlor-alkali raw material salt solution carries out electrolytic oxidation reaction in iodide ion oxidization electrolysis groove, and polarized potential value is 0.20v, stirring velocity 80rpm, reaction 50min.Chlor-alkali salt solution after oxidization electrolysis is through charcoal absorption in adsorber, and it is 10～50min that adsorption temp maintains 50 ℃, adsorption time.In salt solution, the content of iodine is down to 0.14mg/L by the 0.99mg/L before processing.
Embodiment 4
Raw material carries out electrolytic oxidation reaction in iodide ion oxidization electrolysis groove, and polarized potential value is 0.40v, stirring velocity 80rpm, reaction 40min.Chlor-alkali salt solution after oxidization electrolysis is through charcoal absorption in adsorber, and it is 10～50min that adsorption temp maintains 50 ℃, adsorption time.In salt solution, the content of iodine is down to 0.05mg/L by the 0.86mg/L before processing.
Embodiment 5
Factory's chlor-alkali raw material salt solution carries out electrolytic oxidation reaction in iodide ion oxidization electrolysis groove, and polarized potential value is 0.55v, stirring velocity 80rpm, reaction 50min.Chlor-alkali salt solution after oxidization electrolysis is through charcoal absorption in adsorber, and it is 10～50min that adsorption temp maintains 50 ℃, adsorption time.In salt solution, the content of iodine is down to 0.08mg/L by the 0.84mg/L before processing.
Embodiment 6
Factory's chlor-alkali raw material salt solution carries out electrolytic oxidation reaction in iodide ion oxidization electrolysis groove, and polarized potential value is 0.40v, stirring velocity 80rpm, reaction 50min.Chlor-alkali salt solution after oxidization electrolysis is through charcoal absorption in adsorber, and it is 10～50min that adsorption temp maintains 50 ℃, adsorption time.In salt solution, the content of iodine is down to 0.09mg/L by the 1.10mg/L before processing.
Claims (8)
1. the method that the iodide ion in electrochemical oxidation chlor-alkali raw material salt solution is elemental iodine, is characterized in that: under certain pH and polarized potential condition, adopt electrochemical oxidation process that iodide ion in chlor-alkali raw material salt solution is oxidized to elemental iodine.
2. method according to claim 1, is characterized in that: chlor-alkali raw material salt solution is industrial bittern, chloralkali process one-level refined brine, chloralkali process secondary refined brine and the light salt brine after electrolysis treatment.
3. method according to claim 1, is characterized in that: according to the current potential region at the redox peak in cyclic voltammetry curve, selected electric potential is interval, and chlor-alkali raw material salt solution is carried out to potential polarization, when polarized potential is lower, (is less than 0.60V (vsHg/Hg
2sO
4)) time, on platinum electrode, there is electro-oxidation reaction: 2I in iodide ion
--2e
-→ I
2.
4. method according to claim 1, is characterized in that: during electrochemical oxidation, the pH value of chlor-alkali raw material salt solution is 2～6.
5. method according to claim 1, is characterized in that: while adjusting chlor-alkali raw material salt solution pH value, acid used is hydrochloric acid.
6. according to the method described in claim 1 or 3, it is characterized in that: chlor-alkali raw material salt solution is carried out to electrochemicial oxidation, and polarized potential interval is 0.10V～0.60V, and now, the iodide ion in chlor-alkali raw material salt solution is oxidized to elemental iodine.
7. according to the method described in claim 1 or 6, polarized potential interval is 0.10V～0.60V, and the corresponding electrochemical oxidation reactions time is 10min～50min.
8. method claimed in claim 1, it is characterized in that: electrochemical oxidation process is oxidized to elemental iodine by the iodide ion in chlor-alkali raw material salt solution, than in the past, by adding oxygenant iodine oxide ion, electrochemical process was by controlling the different electrochemical reactions under different current densities.Realizing iodide ion and be converted to elemental iodine, is a kind of physical method, does not introduce other chemical compositions, has got rid of because adding oxygenant on the issuable impact of ionic membrane.
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|---|---|---|---|
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105293526A (en) * | 2015-10-26 | 2016-02-03 | 天津科技大学 | Method for purifying iodine in saline water of ionic membrane caustic soda production process |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101935847A (en) * | 2010-10-20 | 2011-01-05 | 昊华宇航化工有限责任公司 | Method for removing trace iodine from salt water for producing sodium hydroxide by electrolysis method |
-
2014
- 2014-06-06 CN CN201410264123.6A patent/CN104109877A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101935847A (en) * | 2010-10-20 | 2011-01-05 | 昊华宇航化工有限责任公司 | Method for removing trace iodine from salt water for producing sodium hydroxide by electrolysis method |
Non-Patent Citations (2)
| Title |
|---|
| EIICHIRO NAKAYAMA ET AL: "Automatic Determination of Iodine Species in Natural Waters by a New Flow-Through Electrode System", 《ANALYTICAL CHEMISTRY》 * |
| 何勇: "粉末活性炭去除盐水中碘的研究", 《中国优秀硕士学位论文全文数据库工程科技Ⅱ辑》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105293526A (en) * | 2015-10-26 | 2016-02-03 | 天津科技大学 | Method for purifying iodine in saline water of ionic membrane caustic soda production process |
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