CN102432123A - Reproducible heavy metal complexing agent and application method thereof - Google Patents

Abstract

The invention aims to provide a reproducible heavy metal complexing agent and an application method thereof. In the method, hydrolyzed collagen serving as a complexing agent is applied to a membrane separating process, and heavy metal copper-containing waste water is integrally treated by performing membrane separation-electrolysis. The method mainly comprises the following steps of: enriching; filtering; concentrating; decomplexing; electrodepositing; refluxing and the like to realize efficient recovery of heavy metal copper-containing waste water.

Description

A kind of renewable heavy metal complexing agent and using method

technical field

The invention belongs to the technical field of water treatment, and in particular relates to a method for treating industrial wastewater, in particular to a method for treating wastewater containing heavy metal copper.

Background technique

Heavy metal wastewater is one of the industrial wastewater that seriously pollutes the environment and is extremely harmful to human health. Heavy metal wastewater comes from a wide range of sources, mainly in electroplating, mining and metallurgy, electronics, machinery manufacturing and chemical industries. With the rapid development of these industries, a large amount of heavy metal wastewater has been discharged, which has increasingly attracted people's attention. According to the different sources and components of wastewater, the treatment methods of heavy metal wastewater are different. Generally speaking, the main methods for treating heavy metal wastewater are: chemical precipitation, adsorption, ion exchange, electrochemical and membrane separation. The chemical precipitation method is easily affected by the precipitating agent and environmental conditions. The concentration of the effluent of the precipitation method often does not meet the requirements, and further treatment is required. The adsorption method has the advantages of simple operation and high metal ion removal efficiency, but there are still post-processing problems after the adsorbent absorbs heavy metals. The enriched eluate containing high concentrations of heavy metals needs further treatment to realize resource recovery. The industrial application of adsorption method. The ion exchange method device is expensive, the processing cost is high, and the resin is easily polluted or oxidized. The electrodeposition method can reduce heavy metal ions to simple substances. After the electrodeposition process, the simple metal substances on the plate can be peeled off, which can easily realize the recovery of resources and generate certain economic benefits. However, the electrodeposition method is only suitable for the treatment of high-concentration heavy metal wastewater, and the treatment of low-concentration heavy metal wastewater requires high power consumption and high investment costs.

Membrane separation technology uses a special semi-permeable membrane to separate the solution, with pressure as the driving force. When the wastewater flows through the membrane surface, the pollutants in it are intercepted, and the water molecules pass through the membrane to purify the wastewater. As a new type of water treatment technology, membrane technology has the advantages of low consumption, high efficiency, and convenient operation. Conducive to the further recycling of heavy metals. The currently used membrane separation technologies are mainly microfiltration technology, ultrafiltration technology, nanofiltration technology and reverse osmosis technology. Nanofiltration and reverse osmosis have high metal removal rates but small membrane pores, low membrane flux, and high operating pressure. They are generally used for drinking water purification. Ultrafiltration membranes and microfiltration membranes have large flux and low operating pressure, but because the membrane pore size is much larger than the diameter of metal ions, they cannot be directly intercepted. It is necessary to add surfactants to form micelles or add water-soluble polymers and metal ions. Complexation increases its volume and is trapped. As a result, a concentrated solution containing high concentrations of metals and organic substances is formed. If it is directly discharged into the environment without further treatment, it will cause secondary pollution. On the other hand, the volume of industrial wastewater is large, and surfactants or complexing agents need to be continuously added during the treatment process, which increases operating costs.

Contents of the invention

The purpose of the present invention is to overcome the problem that the concentrated solution existing in the prior art is difficult to handle and the running cost is high, and provide a kind of reproducible heavy metal complexing agent and its use method, because the complexing property of this complexing agent and metal And the property that it is not easy to be oxidized and reduced in electrodeposition, the complexing agent can be used in the ultrafiltration-electrodeposition combination method, not only can the concentrated solution be effectively treated, reduce the risk of secondary pollution, and the complexing agent can be used in It is regenerated during the electrodeposition process, and the operation cost is effectively reduced through the reuse of the complexing agent.

To achieve the above object, the technical solution adopted in the present invention is:

In the process of treating heavy metal wastewater, a renewable heavy metal complexing agent is used, and the combination of two steps of membrane separation and electrodeposition is used for treatment. The steps of combined treatment include complexing of the complexing agent and copper ions, concentration of the solution, regeneration and recycling of the complexing agent.

The complexing agent and copper ion complexation are realized in the membrane separation process; the solution concentration, complexing agent regeneration and reuse are realized in the electrodeposition step.

The specific plan is:

(1) Put the wastewater containing heavy metal copper to be treated into a regulating tank with a stirrer.

(2) Add hydrolyzed collagen as a complexing agent in the adjustment tank-1, and add NaOH, control the pH of the wastewater after adding and keep it between 5.5-7.0, the speed of the agitator is kept between 400-600rpm, at normal temperature React for 1-2 hours to ensure that all the copper ions are complexed with the hydrolyzed collagen.

(3) Under the action of the lifting pump-1, the wastewater in the regulating tank-1 enters the multi-media filter and ultrafiltration membrane system, and the water molecules pass through the ultrafiltration membrane under pressure to become purified water, and the copper ions in the filtrate are intercepted The rate is more than 90%, and it can be reused in the production process. Copper ions and hydrolyzed collagen complexes are intercepted by the ultrafiltration membrane because they are larger than the micropore diameter of the ultrafiltration membrane, forming a concentrated solution.

(4) The concentrated solution obtained by membrane separation is returned to the adjustment tank-1, and when the concentrated solution in the adjustment tank-1 reaches a concentration ratio of 2-4 times, the lift pump-1 from the adjustment tank to the ultrafiltration membrane system is closed, Turn on the lifting pump-2 between the adjustment tank-1 and the adjustment tank-2, and pump the feed liquid in the adjustment tank-1 into the adjustment tank-2.

(5) Add sulfuric acid to the adjustment tank-2, and control the pH of the wastewater after adding to be between 2-4, so as to decomplex the hydrolyzed collagen and copper ions.

(6) Turn on the lifting pump-3 between the adjustment tank-2 and the flat plate electrodeposition device, pour the solution into the electrolytic tank for electrolysis, copper is precipitated on the cathode plate, and the hydrolyzed collagen remains in the electrolyte, realizing the metal ion Separation from complexing agents.

(7) After the electrodeposition process is finished, open the valve between the electrolytic cell and the adjustment tank-1, and the regenerated hydrolyzed collagen is returned to the adjustment tank-1 for recycling.

The process conditions and functions of each component are stated below:

Conditioning tank-1: Located before the ultrafiltration membrane system, the complexing agent added is hydrolyzed collagen, which is obtained by hydrolyzing the protein in cow, pig and fish fur by conventional methods, and its molecular weight is 2000-3000. Those skilled in the art can obtain it through common technical methods, for example: CN101948900A, CN1903918A, etc. The source of hydrolyzed collagen in the present invention is Hebei Xueyang Gelatin Protein Factory (company address: the north side of 78.2 kilometers away from Wuqian Road, Gucheng Town, Fucheng County, Hebei Province), the product name is hydrolyzed collagen powder, and the CAS number is 9007-34- 5. The mass ratio of the heavy metal copper in the waste water to the added hydrolyzed collagen is 1:10-1:25. Adjust the pH to 5.5-7.0, keep the speed of the agitator between 400-600rpm, and react at room temperature for 1-2 hours;

Multi-media filter: remove suspended solids in water, reduce water turbidity, and meet ultrafiltration water inlet requirements (turbidity is less than 1.0NTU). The existing commercial and mature filters on the market can achieve this technical effect. Such as the JX-010 quartz sand filter (model JHD-18, JHD-22, JHD-36) produced by Qinhuangdao Jiahui Environmental Protection Equipment Co., Ltd., and the YLSS series quartz filter (YLSS) produced by Beijing Yuanlai Water Treatment Equipment Co., Ltd. -500, YLSS-750, YLSS-1000, YLSS-1200), ZWJ29-JDL-3 quartz sand filter (model JDL-3, JDL-6, JDL-10) provided by Beijing (Zhongxi Tai'an) Technical Service Co., Ltd. , JDL-15) etc. What the present invention uses is the quartz sand filter in the multimedia filter. In the separation process of the ultrafiltration membrane system, the ultrafiltration membrane module is a plate and frame type, the membrane material is polyethersulfone membrane, and the molecular weight cut-off is 1000 Daltons. In the process of ultrafiltration separation, the operating pressure used is 0.4-0.6Mpa, the working temperature of wastewater is 25°C-35°C, the average retention rate of copper ions is 90%-92%, and the quality of the effluent water meets the quality standard of industrial circulating water, which can be reused for Industrial circulating water system. The existing commercial and mature components on the market can achieve this technical effect, for example: small microfiltration and ultrafiltration flat membrane separation systems (SY-MU2010, SY-MU2050, SY -MU-2-500), pilot-scale ultrafiltration, nanofiltration, reverse osmosis membrane separation system (SY-UNR-D3-4040); Millipore ultrafiltration system (labscale TFF small tangential flow ultrafiltration system, Congent-M ultrafiltration system, Pellicon ultrafiltration system). Ultrafiltration membrane modules: modified polysulfone (PS) hollow fiber membrane modules (HQM-4040PS, HQM-6040PS) developed and produced by Hangzhou Hongquan Membrane Technology Co., Ltd., Lisheng LH3 series ultrafiltration membrane modules produced by Lisheng Enterprise ( LH3-1060-V, LH3-0680-V, LH3-0660-V, LH3-0650-V, LH3-0450-V). Membrane materials: polysulfone (PS) membrane (PS-20) produced by Sepro Corporation of the United States, polyvinylidene fluoride (PVDF) membrane (PVDF-200, PVDF-350, PVDF-400, PVDF-700), polyacrylonitrile ( PAN) membrane (PAN-50, PAN-200, PAN-350, PAN-400), polyethersulfone (PES) membrane (PES-5, PES-10, PES-20, PES-900C/D); Polyethersulfone (PES) ultrafiltration membranes (PES-1, PES-3, PES-5, PES-8, PES-10, PES-20, PES-30, PES) produced by Membrane Separation Technology Engineering (Beijing) Co., Ltd. -50), polysulfone (PS) ultrafiltration membrane (PS-20, PS-50), polyvinylidene fluoride (PVDF) membrane (PVDF-50, PVDF-100), polyacrylonitrile (PAN) membrane (PAN- 100). In the separation process of the above-mentioned ultrafiltration membrane system, after the ultrafiltration membrane treatment, the heavy metals in the waste liquid are fully concentrated, so that the concentration of metal ions in the concentrated liquid is greatly increased, which is suitable for the recovery of heavy metals by electrodeposition. The ultrafiltration process ends when the concentration ratio reaches 2-4 times.

Regulating tank-2: located before the two-dimensional plate electrodeposition device, adjust the pH to 2-4, keep the rotation speed of the agitator between 400-600rpm, and decomplex the complex of hydrolyzed collagen and copper ions. The devices adopted are also all available to those skilled in the art, such as the electrochemical treatment tank announced by CN03820055.4, the bipolar electrolysis device and unit electrolyzer thereof announced by CN86107225, the electrolytic process for electrochemical process announced by CN1930325 Tank, a kind of inert electrode aluminum electrolytic cell announced by CN1986898, the diaphragm method metal anode electrolytic cell announced by CN1995461, and the cathode rotating partition type electrolytic cell announced by CN2173247.

During the electrodeposition process, the solution is stirred at room temperature, and the stirring speed is 300-500rpm, which can promote the mass transfer process of copper and reduce the adsorption of hydrolyzed collagen on the plate; the electrode material is a pair of graphite anode/stainless steel cathode Electrode, the cell voltage is 6.0V-16.0V, the electrolysis time is 90min-180min, the minimum concentration of Cu ²⁺ after electrodeposition treatment is less than 20mg/L, and the recovery rate of copper on the plate can reach up to 89%. The regeneration rate of hydrolyzed collagen is 84%-86%.

The concentrated solution containing regenerated collagen obtained from the above electrodeposition process is returned to the regulating tank for reuse, mixed with the newly added copper-containing heavy metal wastewater and fully reacted, and then enters the multimedia filter and ultrafiltration membrane under the action of the lift pump System, in the absence of new collagen supplementation, the removal rate of heavy metal copper can reach more than 70%.

Compared with the prior art, the present invention has the following advantages:

First, the application of hydrolyzed collagen in the combined method of polymer-enhanced ultrafiltration and electrodeposition gives full play to the advantages of hydrolyzed collagen: it is easy to form complexes with copper ions and improve the removal rate of copper in the ultrafiltration process , and it is easy to regenerate by decomplexation by a specific method, and it will not be damaged by redox reaction on the plate during the electrolysis process.

Second, hydrolyzed collagen is a natural substance, non-toxic, and less harmful to the environment than surfactants used in ultrafiltration membrane separations.

Third, the regenerated hydrolyzed collagen can be reused in the ultrafiltration process, effectively reducing operating costs.

Description of drawings

Fig. 1 is the flow chart of the usage method of this renewable heavy metal complexing agent.

Detailed ways

Example 1:

The method of the present invention is used to treat copper-containing heavy metal wastewater with a concentration of 100mg/L. The pH value of the influent is 4.6, the water temperature is 25°C, and the hydrolyzed collagen is used as a complexing agent. The water quality is purified through an ultrafiltration membrane system, and the concentrated solution is passed through an electric Copper recovery, regeneration and recycling of hydrolyzed collagen are achieved by deposition method. The hydrolyzed collagen, multi-media filter, ultrafiltration membrane system, two-dimensional plate electrodeposition device, etc. used in this process are all recycled from conventional wastewater. Processing device. The hydrolyzed collagen used in the present invention has a molecular weight of 2000-3000 and is obtained by enzymatic hydrolysis. Specifically: according to the method of CN101948900A, fresh cowhide is used as raw material, after being treated with sodium hydroxide solution, papain and alkaline protease are added in stages, and a compound enzymolysis protection agent is added at the same time, after two enzymatic hydrolysis, the temperature is raised to kill the enzyme, After oxidative decolorization, filtration and ultrafiltration, the retentate is collected and spray-dried to obtain hydrolyzed collagen with a molecular weight of 2000-3000. Or directly purchased from Hebei Xueyang Gelatin Protein Factory, CAS: 9007-34-5. The multi-media filter is ZWJ29-JDL-3 quartz sand filter provided by Beijing (Zhongxi Tai'an) Technology Service Co., Ltd., and the ultrafiltration membrane system is UF-2319 designed and produced by Ande Membrane Separation Technology Engineering (Beijing) Co., Ltd. The experimental machine, the two-dimensional flat plate electrodeposition device, the electrolytic cell is a PP polypropylene polymer material electrolytic cell, and the cathode and anode are respectively stainless steel plate and graphite plate. The specific technological process is as follows: Step 1: Put the waste water containing heavy metal copper to be treated into a regulating tank-1 with an agitator.

Step 2: Adding hydrolyzed collagen as a complexing agent to the adjustment pool-1, the mass ratio of hydrolyzed collagen to copper is 10:1-25:1. Add NaOH, adjust the pH of the waste water after adding to 5.5-7.0, the rotation speed of the stirrer is 400rpm, and react at room temperature for 1 hour to ensure that all the copper ions are complexed with the hydrolyzed collagen.

Step 3: Under the action of the lifting pump-1, the wastewater in the regulating tank-1 passes through the multi-media filter to remove suspended solids in the water, reduce the turbidity of the water, and meet the ultrafiltration water inlet requirements; then enter the ultrafiltration membrane system , the operating pressure used is 0.45Mpa, and the working temperature of wastewater is 25°C. Under the action of pressure, water molecules pass through the ultrafiltration membrane to become purified water. The retention rate of copper ions in the filtrate is 93.1%, which can be reused in the production process. Copper ions and hydrolyzed collagen complexes are intercepted by the ultrafiltration membrane because they are larger than the micropore diameter of the ultrafiltration membrane, forming a concentrated solution.

Step 4: The concentrated solution obtained by membrane separation is returned to the regulating tank-1. When the concentrated solution in the regulating tank-1 reaches a concentration ratio of 2 times, the lift pump-1 from the regulating tank-1 to the ultrafiltration membrane system is closed. Turn on the lifting pump-2 between the adjustment tank-1 and the adjustment tank-2, and pump the feed liquid in the adjustment tank-1 into the adjustment tank-2.

Step 5: adding sulfuric acid to the adjustment pool-2, controlling the pH of the wastewater after adding to 2-4, so as to decomplex the hydrolyzed collagen and copper ions.

Step 6: Turn on the lifting pump-3 between the adjustment tank-2 and the electrolytic tank, the solution is pumped into the electrolytic tank through the lifting pump-3 to carry out the electrodeposition process, and the solution is stirred at room temperature at a stirring speed of 300rpm, which can promote the deposition of copper Mass transfer process and reduce the adsorption of hydrolyzed collagen on the plate; the electrode material is graphite anode/stainless steel cathode paired electrode, the cell voltage is 6.0-16.0V, the electrolysis time is 90min-180min, copper is precipitated on the cathode plate, after The concentration of Cu ²⁺ in the solution after electrodeposition treatment is 18-24 mg/L, and the recovery rate of copper on the pole plate is 88%-90%. At the same time, due to the precipitation of copper, the hydrolyzed collagen is separated from the copper ions, and the hydrolyzed collagen remains in the electrolyte to be regenerated. The regeneration rate of the hydrolyzed collagen is 84% to 86%.

Step 7: After the electrodeposition process is over, open the valve between the electrolytic cell and the adjustment tank-1, and the regenerated hydrolyzed collagen flows back into the adjustment tank-1, and mixes with the newly entered wastewater containing heavy metal copper, and after fully reacting It is pumped into the multi-media filter and ultrafiltration membrane system by the lift pump-1, and the second cycle treatment process starts. In the case that no new complexing agent is added, the removal rate of copper ions is 80%.

Claims (9)

1. the method for use of a renewable heavy metal complexing agent is characterized in that this method carries out the combined treatment of membrane sepn, two steps of galvanic deposit to waste water.

2. method of use as claimed in claim 1 in said combined treatment, is applied to heavy metal containing wastewater treatment with complexing agent, and this application comprises complexing agent and cupric ion complexing and solution concentration, complexing agent regeneration and two steps of reuse.

3. according to claim 1 or claim 2 method of use, it is characterized in that: said membrane sepn step comprises:

(1) the pending waste water that contains heavy metal copper is put into an equalizing tank that has whisking appliance.

(2) in equalizing tank-1, add complexing agent, and add NaOH, the pH that control adds back waste water remains between the 5.5-7.0, and the rotating speed of whisking appliance remains between the 400-600rpm, reacted at normal temperatures 1-2 hour, with guarantee cupric ion all with the complexing agent complexing.

(3) under the effect of lift pump-1, the waste water in the equalizing tank-1 gets into more medium filter, ultrafiltration membrane system, and water molecules becomes through ultra-filtration membrane under pressure purifies waste water, and the cupric ion rejection reaches more than 90% in the filtrating, can be back to production technique.The complex compound that cupric ion and complexing agent form forms liquid concentrator owing to held back by ultra-filtration membrane greater than the micropore size of ultra-filtration membrane.

4. like the described method of use of claim 1-3, it is characterized in that: said electrodeposition step comprises:

(4) liquid concentrator that obtains through membrane sepn is got back in the equalizing tank-1; After the liquid concentrator in the equalizing tank-1 reaches 2-4 concentration rate doubly; Close the lift pump-1 of equalizing tank to ultrafiltration membrane system; Open the lift pump-2 between equalizing tank-1 and the equalizing tank-2, the feed liquid in the equalizing tank-1 is squeezed in the equalizing tank-2.

(5) in equalizing tank-2, add sulfuric acid, control adds the pH of back waste water between 2-4, makes complexing agent and cupric ion decomplexing.

(6) open the lift pump-3 of equalizing tank-2 between the dull and stereotyped electric deposition device, solution is squeezed into carried out electrolysis in the electrolyzer, copper is separated out on negative plate, complexing agent is stayed in the electrolytic solution, has realized separating of metals ion and complexing agent.

(7) after electrodeposition process finishes, open the valve between electrolyzer and the equalizing tank-1, the complexing agent after the regeneration is back in the equalizing tank-1 and recycles.

5. like the described method of use of claim 1-4, it is characterized in that: described complexing agent is a Collagen Hydrolysate, is that protein is through ordinary method hydrolysis gained in ox, pig and the fish fur, and its molecular weight is 2000-3000.

6. like the described method of use of claim 3-5, in step (1), the Collagen Hydrolysate mass ratio of heavy metal copper and adding in the waste water is 1: 10-1: 25.

7. like the described method of use of claim 3-5, in step (3), in the described ultrafiltration membrane system sepn process, hyperfiltration membrane assembly is a plate and frame, and mould material adopts poly (ether sulfone) film, and molecular weight cut-off is 1000 dalton.In the ultra-filtration and separation process, the working pressure that uses is 0.4-0.6Mpa, 25 ℃～35 ℃ of waste water working temperatures.

8. like the described method of use of claim 3-5, in step (6), solution is carried out stirring at normal temperature, stirring velocity is 300-500rpm; Electrode materials is selected graphite anode/stainless steel cathode counter-electrodes for use, and bath voltage is 6.0～16.0V, and electrolysis time is 90～180min.

9. like the described method of use of claim 3-8, the regeneration rate of complexing agent is 84%-86%.

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