阅读说明：本技术 一种有机高硫稳定剂及其合成方法和在重金属污染土壤修复中的应用 (Organic high-sulfur stabilizer, synthesis method thereof and application of organic high-sulfur stabilizer in heavy metal contaminated soil remediation ) 是由 韩宝禄 缪书舟 刘卫国 史学峰 于 2019-09-26 设计创作，主要内容包括：本发明公开了一种有机高硫稳定剂及其合成方法和在重金属污染土壤修复中的应用。将单质硫、助溶剂、碱金属硫化物、催化剂和溶剂混合均匀,搅拌反应后,加入絮凝剂沉淀除杂,即得硫含量高、稳定性好的有机高硫稳定剂。将其应用于重金属污染土壤的修复,可以高效还原土壤中的高价重金属,特别是对六价铬还原性稳定化效果佳,相对于现有技术中常用的多硫化钙、硫化钠等硫系药剂在取得相同稳定化效果的条件下,大幅度降低了硫化剂的用量,降低了重金属污染土壤的修复成本。(The invention discloses an organic high-sulfur stabilizer, a synthesis method thereof and application thereof in heavy metal contaminated soil remediation. Uniformly mixing elemental sulfur, a cosolvent, an alkali metal sulfide, a catalyst and a solvent, stirring for reaction, adding a flocculating agent for precipitation and impurity removal to obtain the organic high-sulfur stabilizing agent with high sulfur content and good stability. The stabilizer is applied to the remediation of the heavy metal contaminated soil, can efficiently reduce high-valence heavy metals in the soil, particularly has good effect of stabilizing the reducibility of hexavalent chromium, greatly reduces the dosage of a vulcanizing agent and reduces the remediation cost of the heavy metal contaminated soil under the condition of obtaining the same stabilizing effect compared with common sulfur-series medicaments such as calcium polysulfide, sodium sulfide and the like in the prior art.)

1. A synthetic method of an organic high-sulfur stabilizer is characterized by comprising the following steps: uniformly mixing elemental sulfur, a cosolvent, an alkali metal sulfide, a catalyst and a solvent, stirring for reaction, adding a flocculating agent for precipitation and impurity removal, and thus obtaining the organic high-sulfur stabilizing agent.

2. The method for synthesizing an organic high-sulfur stabilizer according to claim 1, wherein the method comprises the following steps: the synthetic organic high-sulfur stabilizer comprises the following raw material components in parts by mass:

25-35 parts of alkali metal sulfide;

15-20 parts of elemental sulfur;

8-12 parts of a flocculating agent;

2.5-3 parts of a cosolvent;

3-7 parts of a catalyst.

3. The method for synthesizing an organic high-sulfur stabilizer according to claim 1 or 2, wherein: the alkali metal sulfide is analytically pure sodium sulfide or industrial sodium sulfide; the mass percentage content of the sodium sulfide in the industrial sodium sulfide is about 60 percent.

4. The method for synthesizing an organic high-sulfur stabilizer according to claim 1 or 2, wherein: the flocculating agent comprises at least one of polyacrylamide, aluminum sulfate, polyaluminium chloride and polyferric sulfate.

5. The method for synthesizing an organic high-sulfur stabilizer according to claim 1 or 2, wherein: the catalyst comprises at least one of carboxylic acid sugar, hydroxyl sugar, polysaccharide and xylo-oligosaccharide.

6. The method for synthesizing an organic high-sulfur stabilizer according to claim 1 or 2, wherein: the cosolvent comprises at least one of ethanol, ethylene glycol, propanol and propylene glycol.

7. The method for synthesizing an organic high-sulfur stabilizer according to claim 1, wherein the method comprises the following steps: the solvent is water.

8. An organic high-sulfur stabilizer characterized in that: obtained by the synthesis method of any one of claims 1 to 7.

9. The use of an organic high-sulfur stabilizer according to claim 8, wherein: the heavy metal reduction restoration stabilizer is applied to restoration of heavy metal contaminated soil.

10. The use of an organic high sulfur stabilizer according to claim 9, characterized in that: the heavy metal contaminated soil contains hexavalent chromium; the adding mass of the organic high-sulfur stabilizer in the heavy metal polluted soil is 15-28 times of the mass of hexavalent chromium in the heavy metal polluted soil.

Technical Field

The invention relates to a high-sulfur reagent, in particular to an organic high-sulfur stabilizer which can be used for reducing and repairing heavy metals in heavy metal contaminated soil, and also relates to a preparation method and application thereof in heavy metal contaminated soil repair, belonging to the technical field of heavy metal contaminated soil repair.

Background

In the middle of the 20 th century, the chromium salt production industry has been developed at a high speed, but due to the technical lag and the slight environmental awareness, the produced chromium slag is not treated effectively in time, and most of the accumulated and stockpiled chromium slag is in a disordered stockpiling state. Until 2010, the historical chromium slag stockpiled is not treated, but a large amount of chromium pollution sites left still pose great threats to the environment and human health.

In the chromium-contaminated soil, hexavalent chromium exists not only on the surface of soil particles but also inside the particles, and the hexavalent chromium inside the soil particles has a problem of poor contact with a treatment medium, so that the treatment of the chromium-contaminated soil is difficult.

From the perspective of reducing the health risk of pollutants, the stable solidification technology is a mature, economical and effective technology, is extremely widely applied abroad, and is the most widely used technology in the field of heavy metal contaminated soil remediation. The curing agent used in the technology mainly adopts hydraulic materials such as cement, lime, gypsum and the like, so that the problems of hardening, capacity increasing and the like of soil or other solid wastes are often caused, and the subsequent treatment and utilization are not facilitated.

Compared with the solidification technology, the stabilizer does not change the physical properties of the soil obviously, but can fix the heavy metals and organic matters through the actions of adsorption, precipitation and the like, thereby achieving the purpose of reducing the leaching toxicity and health risk of pollutants. Common hexavalent chromium reduction stabilizers include ferrous salts, sulfites or sulfides, and the like, and most of the hexavalent chromium reduction stabilizers are calcium polysulfide, sodium sulfide, and the like in the existing hexavalent chromium site repair engineering.

The sulfur series medicament always occupies a quite important position in the application of heavy metal soil stabilization and remediation engineering, but has a plurality of defects. In recent years, the reduction and stabilization treatment of chromium-polluted sites by soluble sulfides, such as sodium sulfide, sodium metabisulfite and sodium hydrosulfite, has achieved certain effects. However, the price of sodium hydrosulfite is relatively high, and the large-scale engineering application is limited; stabilizers such as sodium sulfide and sodium metabisulfite are easily oxidized and decomposed in natural environment, and are not beneficial to effective control of reaction.

Therefore, in order to solve the common problems of common sulfur stabilizers, a sulfur hexavalent chromium polluted soil stabilizer which is low in adding ratio, stable in reducing effect, economical, feasible and convenient in engineering application is developed, and has application prospect and popularization value.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the organic high-sulfur stabilizer for repairing the soil polluted by the hexavalent chromium, the organic high-sulfur stabilizer has high unit sulfur content and good stability, can efficiently and stably reduce the high-valence heavy metals in the soil polluted by the heavy metals, and particularly has good reductive stabilization effect of the hexavalent chromium.

In order to realize the technical purpose, the invention provides a synthesis method of an organic high-sulfur stabilizer, which comprises the steps of uniformly mixing single sulfur, a cosolvent, an alkali metal sulfide, a catalyst and a solvent, stirring for reaction, adding a flocculating agent for precipitation and impurity removal, and obtaining the organic high-sulfur stabilizer.

In the synthetic process of the organic high-sulfur stabilizer, sulfide and elemental sulfur are mainly reacted to synthesize a series of polysulfide with higher sulfur content compared with the existing polysulfide compound, and the obtained polysulfide compound has high performance stability and is not easy to decompose, and the main reactions are as follows:

NaS+S→NaS₂

NaS₂+S→NaS₃

.....

NaS_x+S→NaS_x+1

the organic high-sulfur stabilizer has simple synthesis process, low energy consumption and low cost, and can be synthesized at normal temperature.

According to the preferable scheme, the organic high-sulfur stabilizer synthesized by the method comprises the following raw material components in percentage by mass: 25-35 parts of alkali metal sulfide; 15-20 parts of elemental sulfur; 8-12 parts of a flocculating agent; 2.5-3 parts of a cosolvent; 3-7 parts of a catalyst.

In a preferred scheme, the alkali metal sulfide is analytically pure sodium sulfide or industrial sodium sulfide; the mass percentage content of the sodium sulfide in the industrial sodium sulfide is about 60 percent. The raw material sodium sulfide of the invention can be directly industrial sodium sulfide, which greatly reduces the synthesis cost of the organic high-sulfur stabilizer.

In a preferred embodiment, the flocculant comprises at least one of polyacrylamide, aluminum sulfate, polyaluminum chloride and polyferric sulfate. The flocculant adopted by the invention mainly has the function of removing impurities introduced by industrial sodium sulfide, and is mainly used for precipitating the impurities and then filtering the impurities. The preferred mechanism of purifying impurities by the flocculant is mainly that under the action of colloidal substances or electrolytes, impurity particles and tiny flocculation gel particles in a solution neutralize the surface charges of the particles, reduce or eliminate the repulsive force among the particles, so that the impurity particles are combined into a whole and aggregated into a coarse floccule, and then the coarse floccule is separated from water. When the flocculant is a macromolecular compound, impurity particles in the solution react with polar groups or charged groups of the macromolecular compound, and the impurity particles are combined with the macromolecular compound to form coarse flocculent precipitate which is separated from water. The flocculating agent is metered and added in the form of solution with the concentration of 0.5-1.5 g/L.

In a preferred embodiment, the catalyst comprises at least one of carboxylic acid sugar, hydroxyl sugar, polysaccharide and xylo-oligosaccharide. The catalyst is mainly used for promoting the reaction of elemental sulfur and sulfide to be accelerated, shortening the preparation time of the organic high-sulfur stabilizer, reducing the reaction temperature and improving the sulfur content of the organic high-sulfur stabilizer. The carbohydrate catalysts selected by the invention have high activity and selectivity, and promote the synthetic reaction of elemental sulfur and sulfide. The catalyst can be added directly or after being dissolved by a small amount of solvent.

In a preferred embodiment, the cosolvent comprises at least one of ethanol, ethylene glycol, propanol and propylene glycol. The cosolvent has the main functions of improving the reaction rate with sulfide and shortening the preparation time of the organic high-sulfur stabilizer by changing the state of elemental sulfur in a solution, and the dissolution assisting mechanism is mainly that the cosolvent changes the surface polarity of the elemental sulfur so as to change the state of the elemental sulfur in a nonpolar sulfide alkali solution, and the cosolvent can form a soluble complex with the elemental sulfur to accelerate the reaction rate of the elemental sulfur and the alkali sulfide.

Preferably, the solvent is water.

The elemental sulfur is sublimed sulfur, is one of main raw materials for synthesizing the organic high-sulfur stabilizer, and has the effective sulfur content of more than 99 percent.

The preparation method of the organic high-sulfur stabilizer comprises the following specific steps:

1. grinding the sublimed sulfur raw material uniformly, and sieving with a 20-mesh sieve;

2. adding a cosolvent into the sublimed sulfur raw material in proportion, and uniformly mixing;

3. adding alkali metal sulfide in a certain proportion, mixing with the pretreated sublimed sulfur, grinding, and stirring uniformly;

4. adding solvent and catalyst, and continuously stirring until the solid solute is completely dissolved;

5. adding a flocculating agent, flocculating and precipitating impurities, and filtering and removing impurities to obtain the prepared organic high-sulfur stabilizing agent.

The invention also provides an organic high-sulfur stabilizer which is obtained by the synthesis method. The main effective component of the obtained organic high-sulfur stabilizer is NaS₅And NaS₆In mass fraction of>24.4％。

The invention also provides application of the organic high-sulfur stabilizer, which is used as a heavy metal reduction repair stabilizer to repair heavy metal contaminated soil.

In a preferable scheme, the heavy metal contaminated soil contains hexavalent chromium; the adding mass of the organic high-sulfur stabilizer in the heavy metal polluted soil is 15-28 times of the mass of hexavalent chromium in the heavy metal polluted soil. Less than 15 times, the good hexavalent chromium reduction effect cannot be achieved, more than 28 times, the repair effect of the organic high-sulfur stabilizer on the hexavalent chromium is not further improved, and the consumption of the stabilizer is increased.

The basic principle of reducing and stabilizing hexavalent chromium by the organic high-sulfur stabilizer is as follows:

the first stage is as follows: the sulfur series medicament is decomposed, and the decomposed product is mainly H₂S、S₂O₃ ^2-Reducing substances are obtained, and the specific reaction formula is as follows:

3S^X-+2H⁺→H₂S+2S

and a second stage: h₂S、S₂O₃ ^2-And Cr⁶⁺After contacting, Cr⁶⁺Reduction to Cr³⁺And further forming Cr (OH)₃Or chromium iron ore precipitation, elimination of Cr⁶⁺The specific reaction formula of (a) is:

the organic high-sulfur stabilizer mainly uses sulfur ions to reduce and stabilize Cr⁶⁺Is Cr³⁺Compared with other sulfur stabilizers, the organic high-sulfur stabilizer has high effective components, and the number of sulfur ions in one organic high-sulfur stabilizer molecule is high, so that the reduction stabilization efficiency is high under the same additive amount.

Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:

1. the organic high-sulfur stabilizer has high sulfur content under unit concentration (calcium polysulfide product in the market, the main effective component is CaS₅In mass fraction of>18 percent of industrial sodium sulfide product, and the effective component of Na₂S, 60 percent of impurities and crystal water, an organic high-sulfur stabilizer and NaS as an effective component₅And NaS₆In mass fraction of>24.4 percent), stable compound structure, high reducibility, high efficiency of restoring heavy metal by reduction, and particularly hexavalent chromium pollutionThe soil restoration and reduction effect is obvious.

2. The organic high-sulfur stabilizer provided by the invention has the advantages of simple preparation process, extremely low energy consumption, no need of extra energy consumption such as heating and the like, and low raw material cost.

3. The organic high-sulfur stabilizer disclosed by the invention is low in addition amount in the restoration process of hexavalent chromium contaminated soil, ensures the reduction efficiency, is extremely low in compatibilization rate, reduces the adverse effect of sulfide on the physical and chemical properties of the soil, can be used for stabilizing the hexavalent chromium contaminated soil in different degrees by adjusting the addition amount and the proportion, greatly reduces the content of hexavalent chromium in the soil, reduces leaching of the hexavalent chromium, and ensures high long-term stability of the hexavalent chromium contaminated soil.

4. The organic high-sulfur stabilizer can repair various heavy metal polluted sites, such as Ni, Cu and Cr³⁺/Cr⁶⁺Pb, Hg, Cd, etc.

Detailed Description

The following examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.