Preparation Of Imprinted Polymer And Treatment Of Electroplating Wastewater

At present,some areas of nickel-containing wastewater discharge standards in the nickel limit has been as low as 0.1 mg/L,which bring the traditional treatment approach poses a huge challenge.The current process is often utilization of "Advanced Oxidation network and Chemical Precipitation",combined with ion exchange,membrane separation or heavy metal collector coagulation sedimentation in order to ensure the treatment stability of nickel-containing wastewater.But these methods are poor selection,membrane fouling and complex reaction process and other issues.The imprinting technique has been widely used in the treatment of trace contaminants in recent years because of its high selectivity and fast adsorption rate.Although the technology has not yet been reported for nickel-containing wastewater treatment,it can theoretically achieve efficient removal of low-concentration nickel and can be used as a process for the protection of nickel-containing wastewater.In this work,based on the Ni-IIP and EDTANi-MIP,a series of experiments were carried out by static adsorption and fixed-bed continuous flow tests.Meanwhile,the feasibility of this method to deal with low concentration of nickel-containing wastewater has been studied.For the preparation of Ni-IIP,firstly,the preparation conditions were optimized.Methacrylic acid was used as functional monomer,Ni2+ as template,EDTA as ligand and ethylene glycol dimethacrylate as crosslinking agent.The reaction molar ratio was 1:16:20,temperature 50 ℃,15% citric acid as eluent,the polymer has a maximum adsorption capacity of 12.39 mg/g.The characterization of the polymer by BET and FTIR revealed that Ni-IIP had a porous structure and contained characteristic functional groups.At the same time,the adsorption performance evaluation showed that the reaction was spontaneous exothermic,and achieved adsorption equilibrium in 4 min,with two steps to control the adsorption rate characteristics.Ni-IIP showed better specificity for Ni2+,IF was 231 and the selection coefficient were 24 to 49,and it could be used for several times.In order to optimize the preparation conditions of EDTA-Ni-MIP,β-cyclodextrin was selected as the functional monomer,EDTA-Ni as template and hexamethylene diisocyanate as the crosslinking agent.The reaction molar ratio was 1:1:1,temperature 65℃,solvent dimethyl sulfoxide 11 m L/mmol β-CD,15% sodium hydroxide as eluent,the polymer has a maximum adsorption capacity of 15.64 mg/g.The EDTA-Ni-MIP contains characteristic functional groups by FTIR characterization.At the same time,the adsorption performance evaluation showed that the adsorption of EDTA-Ni on the spontaneous heat-absorbing reaction reached the adsorption equilibrium at 20 min,and the adsorption rate was characterized by two steps.The polymer showed better specificity for EDTA-Ni with a selectivity of 102 to 412 and IF was 231,and it could be used for several times.Ni-IIP and EDTA-Ni-MIP have a good performance on the treatment of nickelcontaining wastewater in fixed-bed continuous flow dynamic test.The retention time of Ni-IIP adsorption column was 0.5 min,and penetration volume was 150 BV,the coexistence of organic matter as the main influencing factors.EDTA-Ni-MIP adsorption column residence time was 2 min,the penetration volume was 18 BV,p H of the wastewater as the main influencing factors.For the mixed nickel-containing wastewater,the best water treatment process was to removing EDTA-Ni by EDTA-Ni-MIP column and then removing Ni2+ by Ni-IIP column.