Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/28—Treatment of water, waste water, or sewage by sorption
  • C02F1/286—Treatment of water, waste water, or sewage by sorption using natural organic sorbents or derivatives thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
  • B01J20/24—Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2220/00—Aspects relating to sorbent materials
  • B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
  • B01J2220/48—Sorbents characterised by the starting material used for their preparation
  • B01J2220/4812—Sorbents characterised by the starting material used for their preparation the starting material being of organic character
  • B01J2220/4825—Polysaccharides or cellulose materials, e.g. starch, chitin, sawdust, wood, straw, cotton
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/10—Inorganic compounds
  • C02F2101/20—Heavy metals or heavy metal compounds
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the present invention relates to the technical field of industrial wastewater treatment, and specifically relates to a method for recovering nickel from electroplating wastewater using modified chitosan.
• Methods for removing heavy metals mainly include chemical precipitation, ion exchange, electrodialysis, microbial methods, etc.
• there are common defects such as cumbersome operating procedures, expensive raw materials and equipment, easy to cause secondary pollution, and insensitivity to low-concentration ions.
• electroplating wastewater often contains a large amount of organic matter, which forms stable complexes with heavy metals, making it much more difficult to recover heavy metals.
• the surface of chitosan contains a large number of hydroxyl and amino groups, which can chelate or coordinate with nickel ions.
• chitosan Because it is naturally non-toxic, rich in sources, and easy to biodegrade, it is a green and environmentally friendly natural polymer. Heavy metal ion adsorbent, but chitosan has no selectivity for the adsorption and removal of nickel, and chitosan has high solubility in a pH environment below 5.5, making it difficult to separate from aqueous solutions. These problems limit the use of chitosan.
• the purpose of the present invention is to provide a method for recovering nickel from electroplating wastewater using modified chitosan.
• the operation is simple, the adsorption performance of nickel is excellent, and the adsorption performance of the modified chitosan is stable and does not decrease during recycling.
• a method for recovering nickel from electroplating wastewater using modified chitosan which is characterized by: dissolving chitosan in isopropyl alcohol for freezing pretreatment, and then preparing modified chitosan through esterification reaction with glutamic acid , add the modified chitosan into the nickel-containing wastewater and stir for reaction. After the reaction, add sulfuric acid solution for desorption.
• the above-mentioned freezing pretreatment is to dissolve chitosan in isopropyl alcohol, let it stand for 2-4 hours, then freeze it at -10 ⁇ -12°C for 1-2 hours, and then freeze it at -15 ⁇ -20°C. 4-8h, then use a constant temperature water bath of 45-50°C to thaw. After thawing is completed, perform ultrasonic treatment immediately to gradually turn into a transparent paste.
• the present invention uses isopropyl alcohol to dissolve and swell to a certain extent.
• the permeability of isopropyl alcohol increases initially due to the freeze concentration effect, and more isopropyl alcohol molecules enter the interior of the chitosan.
• the isopropyl alcohol inside the chitosan condenses into ice crystals and grows slowly. Under the mechanical force of the ice crystals, the intra- and intermolecular hydrogen bonds of the chitosan are broken. , which reduces the crystallinity and viscosity of chitosan molecules, making it easier for glutamic acid to undergo esterification modification.
• the adsorption performance of modified chitosan is significantly improved, and it has the advantage of not being used in this process. Acid, alkali and other substances to reduce chemical pollution.
• modified chitosan is to add glutamic acid to dimethyl sulfoxide, heat and dissolve it, then add it to transparent paste chitosan, drop in concentrated sulfuric acid with a mass concentration of 70%, and stir at 40-50 React at °C for 10-20h.
• the dosage ratio of the above-mentioned glutamic acid, dimethyl sulfoxide and concentrated sulfuric acid is 1g:100mL:0.25-0.3mL, and the mass ratio of chitosan and glutamic acid is 2:1.
• the stirring speed is 120-150 rpm
• the pH is adjusted to 2-8
• the temperature is 10-50°C
• the reaction time is 5-60 min.
• the pH is adjusted to 6
• the temperature is 30°C
• the reaction time is 20-30 minutes.
• the ratio of the mass concentration of the above-mentioned modified chitosan in the nickel-containing wastewater to the mass concentration of nickel in the nickel-containing wastewater is 1-1.5:1.
• Step (1) Dissolve chitosan in isopropyl alcohol, let it stand for 2-4h, then freeze it at -10 ⁇ -12°C for 1-2h, and then freeze it at -15 ⁇ -20°C for 4-8h , use a constant temperature water bath of 45-50°C to thaw. Immediately after thawing, perform ultrasonic treatment to gradually turn into a transparent paste. Add glutamic acid to dimethyl sulfoxide, heat to dissolve, and then add to the transparent paste of chitosan.
• Step (2) Add the modified chitosan prepared in step (1) to the nickel-containing wastewater, adjust the pH to 2-8, the temperature to 10-50°C, stir and react at 120-150 rpm for 5-60 minutes, and add the modified chitosan. After neutralizing chitosan, its concentration is nickel mass concentration ratio in nickel-containing wastewater, which is 1-1.5:1;
• Step (3) After the reaction is completed, filter the precipitate, desorb it with sulfuric acid solution, and then wash and dry it for next use.
• the glutamic acid-modified chitosan prepared by the present invention has excellent adsorption performance and selectivity for Ni 2+ .
• the adsorption capacity for Ni 2+ can reach 237.4mg/g, and the time to reach equilibrium adsorption is only 20 minutes. Repeat After being used 5 times, the adsorption capacity can still be maintained at 89.68% of the first adsorption capacity, which has excellent cycle stability.
• Figure 1 Infrared spectrum of modified chitosan prepared by the present invention.
• Figure 2 Effect of pH on adsorption capacity when recovering nickel from modified chitosan prepared in the present invention.
• Figure 3 The effect of temperature on the adsorption amount when recovering nickel from the modified chitosan prepared in the present invention.
• Figure 4 The effect of time on the adsorption amount when recovering nickel from the modified chitosan prepared in the present invention.
• Figure 5 Effect of repeated use times of modified chitosan prepared in the present invention on adsorption performance.
• a method of using modified chitosan to recover nickel from electroplating wastewater as follows:
• Step (1) Dissolve chitosan in isopropyl alcohol, let it stand for 3 hours, then freeze at -12°C for 1 hour, then freeze at -18°C for 8 hours, and finally thaw in a 45°C constant temperature water bath. After thawing is completed, Immediately perform ultrasonic treatment to gradually turn it into a transparent paste. Add glutamic acid to dimethyl sulfoxide. After heating and dissolving, add chitosan to a transparent paste. Drop in concentrated sulfuric acid with a mass concentration of 70%. React for 16 hours at 45°C, then perform suction filtration and washing with deionized water to obtain modified chitosan. The dosage ratio of glutamic acid, dimethyl sulfoxide and concentrated sulfuric acid is 1g:100mL:0.25mL. Chitosan and The mass ratio of glutamic acid is 2:1;
• Step (2) Add the modified chitosan prepared in step (1) to the nickel-containing wastewater, adjust the pH to 6, the temperature to 30°C, and stir for 20 minutes at 130 rpm.
• the modified chitosan is added to the nickel-containing wastewater.
• the ratio of the mass concentration of nickel to the mass concentration of nickel in nickel-containing wastewater is 1:1;
• Step (3) After the reaction is completed, filter the precipitate, desorb it with sulfuric acid solution, and then wash and dry it for next use.
• a new set of characteristic peaks (1600cm -1 ) appears on curve B, which corresponds to the characteristic absorption peak of NH on glutamic acid. The series of changes in the above characteristic peaks indicate that glutamic acid is successfully esterified with chitosan. reaction, glutamic acid-modified chitosan was successfully prepared.
• the modified chitosan prepared by the present invention can achieve good adsorption effect in both acidic and weakly alkaline environments, and changes in pH have little impact on its adsorption performance. There is little change in the adsorption of nickel within the range of 10-50°C. As shown in Figure 3, it can be seen that temperature has little effect on the adsorption performance of nickel by the modified chitosan of the present invention.
• the above shows that the glutamic acid-modified chitosan prepared by the present invention has excellent stability. During the adsorption process in wastewater where only Ni 2+ exists, when the reaction reaches 20 minutes, the adsorption performance can reach the equilibrium adsorption state, and the adsorption capacity reaches 237.4mg/g.
• the glutamic acid-modified chitosan prepared in the present invention was subjected to an adsorption test on wastewater containing metal ions Ni 2+ , Cu 2+ , Cd 2+ and Co 2+ at the same time.
• the specific saturated adsorption performance is shown in Table 1.
• the glutamic acid-modified chitosan prepared by the present invention contains other metal ions at the same time, the adsorption effect of Ni 2+ on Ni 2+ is slightly reduced, but it still has high adsorption performance, and the adsorption capacity of Ni 2+ It can reach 219.5 mg/g and has excellent selectivity.
• the adsorption capacity is much higher than that of other metal ions.
• the time to reach equilibrium adsorption is only 20 minutes, which is also shorter than the equilibrium adsorption time of other metal ions.
• Example 2 Compared with Example 1, the route for preparing modified chitosan is different, as follows:
• chitosan 1g is dissolved in 100mL of 2wt% acetic acid aqueous solution and left to stand for 2 hours, then frozen, then heated and stirred to turn it into a paste, added to the dimethyl sulfoxide solution of glutamic acid, and then slowly dripped Add concentrated sulfuric acid and react at 45°C for 24 hours. After the reaction is completed, filter and wash to obtain modified chitosan; the remaining steps are the same as in Example 1.
• Example 1 Compared with Example 1, no freezing treatment is performed in step (1), and the remaining steps are exactly the same as Example 1.
• Example 1 By comparing Example 1 and Comparative Examples 1 and 2, an adsorption test was conducted in wastewater containing only Ni 2+ .
• the adsorption effect results for Ni 2+ are shown in Table 2.
• the present invention can achieve equilibrium adsorption in 20 minutes, and the saturated adsorption capacity reaches 237.4 mg/g. After five repeated uses, the adsorption effect of Ni 2+ can be maintained at 89.68% of the first time.
• Comparative Example 1 uses acetic acid as the solvent and undergoes freezing treatment.
• Comparative Example 2 uses isopropyl alcohol as the solvent but does not undergo freezing treatment. Its Ni 2+ adsorption capacity is significantly lower than that of the present invention, and after repeated use 5 times, the adsorption performance All showed a significant decline, as shown in Figure 5.
• a method of using modified chitosan to recover nickel from electroplating wastewater as follows:
• Step (1) Dissolve chitosan in isopropyl alcohol, let it stand for 2 hours, freeze at -10°C for 2 hours, then freeze at 120°C for 4 hours, and finally thaw in a 50°C constant temperature water bath. After thawing is completed, proceed immediately. After ultrasonic treatment, it gradually turns into a transparent paste. Add glutamic acid to dimethyl sulfoxide. After heating and dissolving, add chitosan to the transparent paste. Drop in concentrated sulfuric acid with a mass concentration of 70% and heat at 50°C. The reaction was carried out for 10 hours, and then suction filtration and deionized water washing were performed sequentially to obtain modified chitosan. The dosage ratio of glutamic acid, dimethyl sulfoxide and concentrated sulfuric acid was 1g:100mL:0.3mL. Chitosan and glutamine The mass ratio of acids is 2:1;
• Step (2) Add the modified chitosan prepared in step (1) to the nickel-containing wastewater, adjust the pH to 2, the temperature to 10°C, and stir for 60 minutes at 150 rpm.
• the modified chitosan is added to the nickel-containing wastewater.
• the ratio of the mass concentration of nickel to the mass concentration of nickel in nickel-containing wastewater is 1.5:1;
• Step (3) After the reaction is completed, filter the precipitate, desorb it with sulfuric acid solution, and then wash and dry it for next use.
• the adsorption amount of Ni 2+ adsorbed in this example is 232.6 mg/g. After recycling and reusing five times, it is read that the adsorption performance of Ni 2+ still remains 88.63% of the first adsorption.
• a method of using modified chitosan to recover nickel from electroplating wastewater as follows:
• Step (1) Dissolve chitosan in isopropyl alcohol, let it stand for 2-4 hours, freeze at -10°C for 1.5 hours, then freeze at -15°C for 8 hours, and finally thaw in a 48°C constant temperature water bath. The thawing is complete. After that, immediately perform ultrasonic treatment to gradually turn it into a transparent paste, add glutamic acid to dimethyl sulfoxide, heat and dissolve it, then add it to the transparent paste of chitosan, and drop in concentrated sulfuric acid with a mass concentration of 70%. , react at 40°C for 20 hours, and then perform suction filtration and washing with deionized water to obtain modified chitosan.
• the dosage ratio of glutamic acid, dimethyl sulfoxide and concentrated sulfuric acid is 1g:100mL:0.25mL.
• Chitosan The mass ratio of sugar to glutamic acid is 2:1;
• Step (2) The modified chitosan prepared in step (1) is added to the nickel-containing wastewater, adjust the pH to 8, the temperature is 50°C, stir and react at 120 rpm for 5 minutes, and the modified chitosan in the nickel-containing wastewater is The mass concentration ratio to the mass concentration of nickel in nickel-containing wastewater is 1.2:1;
• Step (3) After the reaction is completed, filter the precipitate, desorb it with sulfuric acid solution, and then wash and dry it for next use.
• the adsorption amount of Ni 2+ adsorbed in this example is 235.9 mg/g. After recycling and reusing five times, it is read that the adsorption performance of Ni 2+ still remains 85.94% of the first adsorption.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Environmental & Geological Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Water Supply & Treatment (AREA)
• Engineering & Computer Science (AREA)
• Hydrology & Water Resources (AREA)
• Analytical Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Polysaccharides And Polysaccharide Derivatives (AREA)
• Water Treatment By Sorption (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

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• 2022
  • 2022-03-24 CN CN202210292516.2A patent/CN114671483B/zh active Active
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