CN107381705A - A kind of method of a variety of cation heavy metals in phase transformation regulation and control separation and recovery water - Google Patents

Abstract

The invention belongs to the technical field of sewage treatment and discloses a method for separating and recovering multiple cationic heavy metals in water through phase transition control. The nano-adsorbent material is added to the sewage containing a variety of cationic heavy metals for adsorption, the adsorbed mud and water are added to the reactor, and CO ₂ gas is introduced under airtight and stirring conditions to react, so that the nano-adsorbent material generates soluble The bicarbonate is transferred from the solid phase to the solution phase, and then converted into solid-phase carbonate or basic carbonate by heating, calcined or dried and ground to obtain a regenerated nano-adsorption material. At the same time, a variety of cationic heavy metals react with CO ₂ and water to form insoluble precipitates, which are separated by size through the hydrothermal reaction of mineralizers. The consumption material of the method of the invention is carbon dioxide, no new impurities are introduced, and the enrichment and recovery of various cationic heavy metals and the regeneration and reuse of nanometer adsorption materials can be realized.

Description

A method for separating and recovering multiple cationic heavy metals in water by phase change regulation

technical field

The invention belongs to the technical field of sewage treatment, and in particular relates to a method for phase transition control, separation and recovery of various cationic heavy metals in water.

Background technique

In the past ten years, the development and expansion of industrialization has brought huge social wealth to our country. At the same time, the massive discharge of pollutants has caused serious pollution to the environment and caused many environmental hazards. For example, the copper industry pollution in Jiangxi Province reported in 2012 caused water and soil pollution due to the massive discharge of sewage containing heavy metals, which threatened the health of more than 400,000 local residents and caused adverse social impacts; It was reported in 2012 that children’s blood lead exceeded the standard in Dongtang Town, Renhua County, Shaoguan City, Guangdong Province. The blood lead of 159 children exceeded 100 micrograms per liter, which reached the standard for high blood lead disease. One of the reasons was the discharge of local enterprises. Lead-containing pollutants; the chromium pollution in Qujing, Yunnan, which occurred in 2011, caused large-scale water and soil pollution. In frequent public hazard incidents, heavy metals such as copper, lead, and chromium are often the main pollutants in the incidents. Sewage containing heavy metals will cause serious damage to the ecosystem after entering the ecosystem, pollute the food chain, and cause serious damage to the ecosystem in organisms including humans. enrichment, leading to serious consequences. The Ministry of Environmental Protection has listed the solution to the heavy metal pollution that endangers public health as a key position in the national pollution prevention and control work in 2010. As of 2014, my country's industrial sewage treatment volume is about 50 billion tons, and industrial sewage contains a large amount of mercury, arsenic, cadmium, and lead. , chromium, copper, zinc and other toxic and harmful heavy metals. Therefore, the research and development of treatment technologies for sewage containing heavy metals, especially low-consumption, non-polluting and recyclable treatment technologies will be urgently needed in my country for a long time to come. The inevitable requirement of common development goals.

So far, the research on heavy metal-containing sewage has been conducted for quite a long time, accumulated a lot of experience, and formed many effective and mature treatment methods, such as chemical precipitation method, electrochemical method, membrane separation method, ion exchange method , adsorption method, biological method, etc. The chemical precipitation method can treat high-concentration heavy metal wastewater by adding chemical reagents to the wastewater, and the treatment effect is ideal. For example, the recovery rate of Pb ²⁺ and Hg ²⁺ in the wastewater can reach more than 99.90%, but The traditional chemical precipitation method needs to add a large amount of chemical agents, and there are common problems such as high operating cost and secondary pollution; the electrochemical method deposits heavy metals in wastewater through oxidation-reduction reactions, achieving the purpose of separation and recovery, reliable operation, and removal High rate, heavy metals can be recycled. However, the electrolytic treatment requires high investment and will produce by-products. Conditions such as wastewater quality and heavy metal concentration will have a greater impact on the removal efficiency and current efficiency of the electrolytic method; the membrane separation method does not change the physical and chemical properties of the wastewater, and the separation efficiency is high. The operation is mature and reliable, and heavy metals can be separated and recovered. However, there are problems such as high investment cost, high energy consumption, easy pollution of semi-permeable membrane, and post-treatment of concentrated solution; the ion exchange method has a high removal rate of heavy metal ions, and can achieve the purpose of recovering heavy metals. However, there are high investment and operating costs, and problems such as desorption and regeneration of ion exchange resins limit its application range; biological methods have the advantages of wide adaptability, high selectivity, good tolerance to organic pollutants, and high and low concentrations. However, at present, most of the research on biological methods is in the laboratory stage, and there are few applications in actual production; the adsorption method is widely used, easy to operate, and does not produce secondary pollution, but the recovery of heavy metals, regeneration and reuse of adsorbents are difficult. The operation of the system brings certain problems.

Most of the domestic patents for the treatment of heavy metal-containing sewage are based on one or more of the above-mentioned principles plus their respective designs. For example, CN1554596 introduces a chemical precipitation-membrane separation method that can reduce the heavy metal content in the treated water to below 1 mg/L, but the adjustment of pH and the precipitation process will consume a large amount of reagents, and the membrane separation module also has the problem of membrane pollution, and the treatment cost is high;

CN101381074 introduces a chemical precipitation method using hydrogen sulfide. In the process, the sulfide can be regenerated into hydrogen sulfide through acid treatment, but this method needs to consume hydrochloric acid, and needs special equipment for using hydrogen sulfide, which has the problems of high cost and large consumption ; CN102531233A introduces a method for ion exchange-chemical precipitation recovery of chromium, which has high efficiency and good effect, but sodium hydroxide and sodium sulfide are consumed during the desorption precipitation process, which has problems of high cost and safe operation; CN102815831A introduces A chelation-electrolysis heavy metal recovery method has been developed. This method has good treatment effect, high recovery rate of heavy metals, and good operability. However, the system device is complex, and chemical reagents are required to be consumed for chelation, precipitation, and network breaking. Changes in water quality will affect electrolysis. Efficiency; CN106044965A has introduced a kind of electrolysis device that has combined anion-cation exchange membrane, and this device structure is simple, easy to use, can carry out electrolysis and electrodialysis treatment, but for the water quality of sewage and the requirement of anion-cation exchange membrane strict; CN203229428U has introduced A system consisting of adsorption-reverse osmosis-ion exchange has a good treatment effect and the removal rate of heavy metals can reach more than 99%. However, both the adsorption and reverse osmosis systems require regular maintenance, and the desorption of the ion exchange system requires the consumption of chemicals and operation and maintenance costs. high. It can be seen from the above examples that the current treatment methods for heavy metal-containing sewage can achieve quite good treatment effects, and the heavy metals contained can also be recovered stably, but there are generally high investment, large consumption of chemicals, high operating costs, and by-products. question.

Therefore, the adsorption sewage treatment technology based on the development of various high-efficiency and low-cost adsorption materials has become a hot spot in the research and application of heavy metal separation and recovery in industrial sewage, but there are still some common problems in the application of this technology, such as , heavy metals can only be adsorbed and accumulated on the surface of the adsorption material, and new pollutants formed by the combination of the adsorption material and the heavy metal are wrapped on the surface of the material to form new hazardous waste. Directional separation and recovery cannot be achieved when a variety of heavy metals coexist.

In response to the above problems, our technical team previously disclosed a method for enriching low-concentration heavy metals in water with a recyclable magnesium hydroxide adsorbent (201010121643.3). However, this method can only achieve the separation and enrichment of heavy metal anions. The principle is to generate magnesium carbonate trihydrate which has almost no adsorption effect on heavy metal anions through the reaction of _CO2 and magnesium hydroxide, so as to realize the desorption and separation and enrichment of heavy metal anions. But for a variety of cationic heavy metals that exist in the environment, it is also necessary to find a better solution.

Contents of the invention

In view of the above shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a method for phase transition control, separation and recovery of various cationic heavy metals in water.

The object of the invention is achieved through the following technical solutions:

A method for separating and recovering multiple cationic heavy metals in water through phase change regulation, comprising the following steps:

(1) adding the nano-adsorbent material to the sewage containing various cationic heavy metals for stirring and adsorption, and separating the solid and liquid to obtain the nano-adsorbent material slurry adsorbed with various cationic heavy metals and purified water after adsorption treatment; the nano-adsorbent material Refers to substances that can react with _CO2 in the presence of water to form soluble bicarbonate;

(2) Add the nano-adsorption material slurry and water obtained in step (1) with various cationic heavy metals to the reactor, and feed _CO gas under airtight and stirring conditions until the system pressure is 0.1-10Mpa to react, so that the nano- The adsorption material reacts in the presence of excess CO ₂ and water to form soluble bicarbonate, which is transferred from the solid phase to the solution phase. At the same time, the adsorbed various cationic heavy metals react with CO ₂ and water to form insoluble precipitates. Solid-liquid separation, realize the separation of various cationic heavy metals and nano-adsorption materials;

(3) converting the soluble bicarbonate solution phase obtained in step (2) into solid-phase carbonate or basic carbonate by heating, and the gained solid phase is calcined or dry-ground to obtain a regenerated nano-adsorption material;

(4) adding the insoluble precipitates of multiple cationic heavy metals obtained in step (2) into water, and then adding a mineralizer to carry out hydrothermal reaction to separate and obtain different cationic heavy metals.

Further, the nano-adsorbent refers to nano-magnesium hydroxide or nano-calcium carbonate. Nano-magnesium hydroxide can be synthesized by chemical and physical methods, and it can also be that high-temperature heated magnesium oxide is directly added to the nano-scale magnesium hydroxide generated in the stirring heavy metal-containing sewage; the high-temperature heated magnesium oxide is Refers to magnesium oxide heated at 100-700°C for 1-3 hours. Nano-calcium carbonate comes from chemical and physical methods or from natural biological calcium carbonate such as oyster shells.

Further, the various cationic heavy metals include Hg ²⁺ , Cd ²⁺ , Cu ²⁺ , Pb ²⁺ , Zn ²⁺ , Ni ²⁺ , Co ²⁺ , Eu ²⁺ , Sn ²⁺ , Fe ³⁺ at least two of the .

Further, the purified water after the adsorption treatment in step (1) can be discharged if it meets the discharge standard, and can be subjected to secondary treatment if it does not meet the discharge standard.

The principle of the present invention is: pour the nano-adsorbent material into the stirring sewage containing various cationic heavy metals, continue to stir until the nano-adsorbent material reaches adsorption or reaction equilibrium, and use methods such as precipitation and centrifugation to make the nano-adsorbent material coated with heavy metals mud Separate from the treated water; if the treated water meets the discharge standard, it can be discharged, if it does not meet the discharge standard, it can be treated twice, and the obtained nano-adsorbent slurry is desorbed and regenerated. The steps of the desorption process are as follows: import the nano-adsorption material slurry coated with various cationic heavy metals into a closed reactor, add a corresponding amount of water according to different pollutant types, and then introduce carbon dioxide while controlling the pressure in the reactor The nano-adsorption material reacts with carbon dioxide to gradually generate the corresponding bicarbonate, and the enriched heavy metal reacts with carbon dioxide to generate the corresponding heavy metal carbonate and heavy metal basic carbonate nano-solid phase, which can be separated according to the different dissolution states in the solution. Insoluble heavy metal carbonates or basic carbonates of various cationic heavy metals are added to water, and then mineralizers are added for hydrothermal reaction. The addition of mineralizers and hydrothermal reaction conditions are to make different cationic heavy metals pass through nanocrystals. The secondary growth generates heavy metal phases of different sizes, and then different cationic heavy metals are obtained through size fractionation and directional separation (for specific mineralizers and hydrothermal reaction principles, please refer to patents 200610135382.4, 201610501716.9, 201610502468.X, 201610502493.8, 201610502498.0).

Method of the present invention has following advantage and beneficial effect:

(1) The method of the present invention can not only separate and recover cationic heavy metals, but also regenerate nano-adsorption materials. The nanometer adsorption material can continuously absorb, enrich, separate and recover cationic heavy metals from sewage containing cationic heavy metals through closed phase change cycle. The treated water can meet the discharge standard, cationic heavy metals can be enriched and recycled, nano-adsorbent materials can be regenerated and reused, and the material consumed in the process is carbon dioxide, and no new impurities are introduced into the treated water.

(2) In the method of the present invention, insoluble heavy metal carbonates or basic carbonic acid of various cationic heavy metals can be obtained by adding mineralizers and hydrothermal reaction, and obtaining different cationic heavy metals through directional separation through size classification.

(3) The method of the invention requires simple equipment, easy operation, large-scale treatment, continuous operation, low cost and ideal environmental, social and economic benefits.

detailed description

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example 1

Adsorption and Separation of Pb ²⁺ /Zn ²⁺ in Water by Magnesium Hydroxide

(1) get concentration and be that 100mg/L Pb ²⁺ solution 50mL and concentration be 100mg/L Zn ²⁺ solution 50mL mix, add 50mg magnesium hydroxide in the mixed solution, carry out centrifugation after stirring 12 hours with agitator, Magnesium hydroxide mud and treated clear liquid are obtained. The concentration of Pb ²⁺ and Zn ²⁺ in the obtained supernatant was detected, and the measured concentration of Pb ²⁺ was 0.062 mg/L, and the concentration of Zn ²⁺ was 0.019 mg/L.

(2) Take the magnesium hydroxide slurry obtained in step (1) and place it in a stainless steel container, add 10 mL of deionized water for stirring, seal the container and feed carbon dioxide gas, keep the container pressure at 0.5 Mpa, and react for 12 hours. Magnesium hydroxide reacts in the presence of excess CO ₂ and water to form soluble magnesium bicarbonate, which is transferred from the solid phase to the solution phase, while the adsorbed Pb ²⁺ and Zn ²⁺ react with CO ₂ to form insoluble magnesium bicarbonate carbonate. The obtained mixture was filtered, and the obtained filter residue was washed with distilled water and subjected to XRD analysis, and the results showed that the solid components were lead carbonate and zinc carbonate.

(3) Heat the filtrate obtained in step (2) to 100° C. for 2 hours, and obtain 4MgCO ₃ ·Mg(OH) ₂ ·5H ₂ O(S) after filtration. Magnesium oxide can be obtained by heating the obtained solid at 600°C for 2 hours. After heating, it can be directly poured into the nano-scale magnesium hydroxide generated in the sewage containing Pb ²⁺ /Zn ²⁺ , and the next round of adsorption operation can be carried out.

(4) Take the mixed solid obtained in step (2), add 20mL of 1M sodium bicarbonate solution and 20mL of clear water, heat at 120°C for 3h, centrifuge the resulting mixture for 1min at 1000r/min, and use lead carbonate and carbonic acid The difference in zinc particle size separates lead and zinc.

Example 2

Adsorption and Separation of Eu ²⁺ /Pb ²⁺ in Water by Magnesium Hydroxide

(1) get the Eu ²⁺ solution 50mL that concentration is 100mg/L and the Pb ²⁺ solution 50mL that concentration is 100mg/L mix, add 50mg magnesium hydroxide in the mixed solution, carry out centrifugation after stirring 12 hours with agitator, Magnesium hydroxide mud and treated clear liquid are obtained. The concentrations of Eu ²⁺ and Pb ²⁺ in the obtained clear liquid were detected, and the measured Eu ²⁺ concentration was 0.055 mg/L, and the Pb ²⁺ concentration was 0.052 mg/L.

(2) Take the magnesium hydroxide slurry obtained in step (1) and place it in a stainless steel container, add 10 mL of deionized water for stirring, seal the container and feed carbon dioxide gas, keep the container pressure at 0.5 Mpa, and react for 12 hours. Magnesium hydroxide reacts in the presence of excess CO ₂ and water to form soluble magnesium bicarbonate, which is transferred from the solid phase to the solution phase, while the adsorbed Eu ²⁺ and Pb ²⁺ react with CO ₂ to form insoluble magnesium bicarbonate precipitation. The obtained mixture is filtered, and the obtained filter residue is washed with distilled water and subjected to XRD analysis, and the result shows that the solid components are europium carbonate and basic lead carbonate.

(3) Heat the filtrate obtained in step (2) to 100° C. for 2 hours, and obtain 4MgCO ₃ ·Mg(OH) ₂ ·5H ₂ O(S) after filtration. Magnesium oxide can be obtained by heating the obtained solid at 600°C for 2 hours. After heating, it can be directly poured into the nano-scale magnesium hydroxide generated in the sewage containing Eu ²⁺ /Pb ²⁺ , and the next round of adsorption operation can be carried out.

(4) Take the mixed solid obtained in step (2), add 20mL of 1M sodium bicarbonate solution and 20mL of clear water and heat at 120°C for 3h, centrifuge the resulting mixture for 1min at 1000r/min, and use europium carbonate and lead carbonate The difference in particle size separates europium from lead.

Example 3

Adsorption and Separation of Sn ²⁺ /Fe ³⁺ in Water by Magnesium Hydroxide

(1) get concentration and be that 100mg/L Sn ²⁺ solution 50mL and concentration be 100mg/L Fe ³⁺ solution 50mL mix, add 50mg magnesium hydroxide in the mixed liquor, carry out centrifugation after stirring with agitator 12 hours, Magnesium hydroxide mud and treated clear liquid are obtained. The concentrations of Sn ²⁺ and Fe ³⁺ in the obtained clear liquid were detected, and the measured concentration of Sn ²⁺ was 0.024 mg/L, and the concentration of Fe ³⁺ was 0.015 mg/L.

(2) Take the magnesium hydroxide slurry obtained in step (1) and place it in a stainless steel container, add 10 mL of deionized water for stirring, seal the container and feed carbon dioxide gas, keep the container pressure at 0.5 Mpa, and react for 12 hours. Magnesium hydroxide reacts in the presence of excess CO ₂ and water to form soluble magnesium bicarbonate, which is transferred from the solid phase to the solution phase, while the adsorbed Sn ²⁺ and Fe ³⁺ react with CO ₂ to form insoluble magnesium bicarbonate in the presence of water. precipitation. The obtained mixture was filtered, and the obtained filter residue was washed with distilled water and subjected to XRD analysis, and the results showed that the solid components were tin hydroxide and iron hydroxide.

(3) Heat the filtrate obtained in step (2) to 100° C. for 2 hours, and obtain 4MgCO ₃ ·Mg(OH) ₂ ·5H ₂ O(S) after filtration. Magnesium oxide can be obtained by heating the obtained solid at 600°C for 2 hours. After heating, it can be directly poured into the nano-scale magnesium hydroxide generated in the sewage containing Sn ²⁺ /Fe ³⁺ , and the next round of adsorption operation can be carried out.

(4) Take the mixed solid obtained in step (2), add 20 mL of nitric acid solution and 20 mL of clear water, stir with a stirrer for 30 min, and filter the mixture to obtain tin oxide solid and ferric nitrate solution.

Example 4

Adsorption and Separation of Sn ²⁺ /Fe ³⁺ in Water by Calcium Carbonate

(1) getting concentration is that 100mg/L Sn ²⁺ solution 50mL and concentration are 100mg/L Fe ³⁺ solution 50mL mix, add 50mg calcium carbonate in the mixed liquor, carry out centrifugation after stirring with agitator 12 hours, obtain Calcium carbonate slurry and treated supernatant. The concentrations of Sn ²⁺ and Fe ³⁺ in the obtained clear liquid were detected, and the measured concentration of Sn ²⁺ was 0.102 mg/L, and the concentration of Fe ³⁺ was 0.085 mg/L.

(2) Take the calcium carbonate slurry obtained in step (1) and place it in a stainless steel container, add 10 mL of deionized water for stirring, seal the container and feed carbon dioxide gas, keep the container pressure at 0.5 Mpa, and react for 12 hours. Calcium carbonate reacts in the presence of excess CO ₂ and water to form soluble calcium bicarbonate, which is transferred from the solid phase to the solution phase, while the adsorbed Sn ^{2 +} and Fe ³⁺ react with CO ₂ in the presence of water to form insoluble precipitates . The obtained mixture was filtered, and the obtained filter residue was washed with distilled water and subjected to XRD analysis, and the results showed that the solid components were tin hydroxide and iron hydroxide.

(3) Heat the filtrate obtained in step (2) to 100° C. for 2 hours, and obtain crystalline calcium carbonate after filtering. The obtained solids can be ground and dried to obtain calcium carbonate solids, and can be directly poured into the sewage containing Sn ²⁺ /Fe ³⁺ after the regeneration is completed to carry out the next round of adsorption operation.

(4) Take the mixed solid obtained in step (2), add 20 mL of nitric acid solution and 20 mL of clear water, stir with a stirrer for 30 min, and filter the mixture to obtain tin oxide solid and ferric nitrate solution.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (3)

1. a kind of method of a variety of cation heavy metals in phase transformation regulation and control separation and recovery water, it is characterised in that comprise the following steps：

(1) nano adsorption material is added in the sewage containing a variety of cation heavy metals and is stirred absorption, separation of solid and liquid, Obtain being adsorbed with a variety of cation heavy metals nano adsorption material mud and adsorption treatment after purified water；The nano adsorption Material refers to energy and CO₂Reaction generates the material of soluble bicarbonate under the conditions of existing for water；

(2) the nano adsorption material mud of a variety of cation heavy metals will be adsorbed with obtained by step (1) and water is added to reactor In, it is passed through CO under closed and stirring condition₂Gas to system pressure is that 0.1~10Mpa is reacted, and nano adsorption material is existed Excessive CO₂And water it is existing under the conditions of the soluble bicarbonate of reaction generation, solution is transferred to by solid phase, adsorbed simultaneously A variety of cation heavy metals and CO₂And water it is existing under the conditions of reaction generation infusible precipitate, separation of solid and liquid, realize a variety of sun The separation of ion heavy metal and nano adsorption material；

(3) by soluble bicarbonate solution obtained by step (2) mutually by carbonate or alkali formula carbon that thermal conversion is solid phase Hydrochlorate, gained solid phase is through calcining or drying and grinding, the nano adsorption material regenerated；

(4) infusible precipitate of a variety of cation heavy metals obtained by step (2) is added to the water, then adds mineralizer and carry out Hydro-thermal reaction, isolated different cation heavy metal.

2. the method for a variety of cation heavy metals in a kind of phase transformation regulation and control separation and recovery water according to claim 1, it is special Sign is：Described nano adsorption material refers to nano-sized magnesium hydroxide or nano-calcium carbonate.

3. the method for a variety of cation heavy metals in a kind of phase transformation regulation and control separation and recovery water according to claim 1, it is special Sign is：A variety of cation heavy metals include Hg²⁺、Cd²⁺、Cu²⁺、Pb²⁺、Zn²⁺、Ni²⁺、Co²⁺、Eu²⁺、Sn²⁺、Fe³⁺In At least two.