Study On Treatment Of Electroplating Wastewater With New Inorganic Polymer Flocculant

Electroplating technology is a kind of modern processing technology which is widely used.It mainly uses electrolysis to coat a thin metal film on the surface of the substrate material,thereby improving its wear resistance,heat resistance and corrosion resistance,etc.It has a wider use surface and stronger practicality in life.However,with the continuous development of electroplating technology,people can get great benefit in the economy,which will inevitably bring environmental pollution problems.The waste water produced in electroplating process contains heavy metal ions such as Cu2+,Ni2+ and so on.These heavy metal ions have the characteristics of high content,high toxicity,accumulative,latent and biodegradable,etc.If we do not take effective measures to control heavy metal ions effectively,but let them be discharged,it will do great harm to the ecological environment and human health.Therefore,it is of great practical significance to study the treatment technology of heavy metal ions.Because of its simple process and low investment,flocculant has been used as an important method to treat heavy metal wastewater.Although the flocculant widely sold in the market have certain effects,the effects of network capture and bridging are poor,the removal rate of heavy metal ions is low and the flocculation velocity is slow.So the purpose of this paper is to develop a new inorganic polymer flocculant with high removal efficiency and good flocculation effect.In this paper,a new type of inorganic polymer flocculant-polyaluminum vanadium sulfate(PAVS)was synthesized by the method of space trapping and bridging copolymerization with aluminum potassium sulfate dodecahydrate?vanadium pentoxide.sulfuric acid and sodium bicarbonate.The optimal conditions for the preparation of PAVS were determined by studying the effect of synthesis conditions on the removal of copper and nickel ions in electroplating wastewater,and the structure and morphology of the PAVS prepared under the optimal conditions were characterized;Then the PAVS was applied to copper plating wastewater and nickel plating wastewater,the optimum flocculation conditions of PAVS flocculant for treating copper and nickel wastewater were studied;Finally,the flocculation effect of flocculant PAVS on electroplating copper and nickel wastewater was investigated,which was mainly aimed at the removal rate of copper ion?nickel ion?chromaticity and COD,and compared with those of alum(Alum)?polyferric sulfate(PFS)and polyaluminium sulfate(PAS).The results of the study are as follows:(1)The PAVS was prepared by space capture and bridging copolymerization.Orthogonal test and single factor test were designed to optimize the synthesis conditions.The optimum material ratio was determined as follows:n(KAl(SO4)2·12H2O):n(H2SO4):n(V2O5):n(NaHCO3)= 1:0.5:0.8:2.8,the best process conditions:at 60? temperature,reaction time 3.5 h.(2)The PAVS prepared under the optimal synthesis conditions was characterized by IR,SEM and XRD.The results showed that PAVS has polyhydroxyaluminum structure similar to PAS,and it is a macromolecular substance with network structure,which effectively improves its adsorption arresting effect.(3)When using PAVS to treat copper containing wastewater,the best treatment effect is obtained when pH 7.5,water temperature 20?,settling time 24 min and flocculant dosage 3.0 mL·L-1,the best treatment effect was obtained by using PAVS in treating copper containing wastewater;The optimum flocculation conditions for nickel wastewater were as follows:pH value was 9.0,water temperature was 20 ?,settling time was 30 min and the dosage of flocculant was 5.0 mL·L-1.(4)In the comparative experiment of flocculation effect of flocculant,the content of chromaticity COD,copper and nickel ion in wastewater was detected and analyzed.The results showed that the treatment of copper and nickel containing wastewater with PAVS was carried out.Under the optimum dosage,the removal rates of chromaticity were as high as 98.5%and 98.8%,respectively,and the removal rates of COD were 66.9%and 60.5%respectively.Compared with aluminium?PFS and PAS,PAVS has better effect on the removal of colority and COD in electroplating wastewater than the three flocculants.In addition,the dosage of PAVS was less and the settlement performance was good.It showed that PAYS was a new and efficient inorganic high molecular flocculant.