Study On Process Conditions Of Separation And Recovery Of Copper And Nickel From Electroplating Wastewater

Copper-nickel electroplating wastewater contains a large amount of Cu²⁺and Ni²⁺.Excessive heavy metals will directly affect the growth and development of organisms,damage physiological and biochemical functions,and even cause death.However,heavy metals are valuable resources and are widely used in industrial production.Therefore,it is of great practical significance to study a process that not only can treat heavy metals in wastewater,but also can recycle them for recycling.In this paper,two kinds of PAN-based ion exchange fibers with low cost and simple synthesis method were synthesized and characterized.By investigating the adsorption properties of PAN-based fibers on copper and nickel,the process conditions of effective separation and recovery of Cu²⁺and Ni²⁺in electroplating wastewater were studied.The main research contents are as follows:?1?Two kinds of PAN-based ion exchange fibers were synthesized according to the synthesis technology studied by the research group from polyacrylonitrile fibers.One is PAN-based weakly basic polyamine type ion exchange fiber,which is denoted as PAN-NHx.The other is PAN-based weakly acidic sodium carboxylate ion exchange fiber,which is designated as PAN-COONa.Then the structure and properties of the fibers were characterized.?2?The adsorption properties of two PAN-based ion exchange fibers for single metal ions were investigated.The study found that the adsorption properties of two PAN-based fibers on single Cu²⁺and single Ni²⁺in simulated electroplating wastewater are significantly different.Within the set experimental conditions,the maximum saturated adsorption capacity of PAN-NHx fiber to Cu²⁺reached 197.84mg/g,while the maximum saturated adsorption capacity of Ni²⁺was only 45.33 mg/g;the maximum saturated adsorption capacity of PAN-COONa fiber to Cu²⁺was 142.16mg/g,and the maximum saturated adsorption capacity for Ni²⁺was 170.03 mg/g.The adsorption processes of single Cu²⁺and single Ni²⁺by the two fibers accords with the Langmuir isotherm adsorption model and the quasi-second-order kinetic equation,which is dominated by chemical adsorption.?3?The process conditions of separating and recovering Cu²⁺and Ni²⁺from mixed simulated electroplating wastewater was studied.The effect of various parameters on the adsorption performance of PAN-NHx fiber during static adsorption was analyzed.The results show that:PAN-NHx fiber have the largest difference in adsorption amount of Cu²⁺and Ni²⁺at pH 3;the adsorption tends to equilibrium after60 min;the maximum saturated adsorption capacity of Cu²⁺was 211.01 mg/g,and the maximum saturated adsorption capacity for Ni²⁺was 23.10 mg/g.According to the static adsorption results,the process flow for separating and recovering Cu²⁺and Ni²⁺was designed.?4?The process of separating and recovering Cu²⁺and Ni²⁺from mixed simulated wastewater was analyzed by discussing the influence of flow rate and solution concentration on the adsorption process of the column.The effect of flow rate on the regeneration of PAN-NHx fiber adsorption column and its reutilization performance were also studied.The results show that the mixed simulated electroplating wastewater containing 100 mg/L Cu²⁺and 100 mg/L Ni²⁺can pass through the PAN-NHx fiber adsorption column,which can achieve better separation effect.The saturated adsorption capacity of PAN-NHx fiber adsorption column for Cu²⁺is 161.71 mg/g,the concentration of Cu²⁺enriched by elution is 1066.67 mg/L,and the purity reaches 90.4%.After secondary adsorption desorption treatment,the recovered Cu²⁺content is from 90%increased to over 99%.The concentration of Ni²⁺in the first 24.5%of the effluent is 80.41 mg/L,and the purity is over 99%;it passes through the PAN-COONa fiber adsorption column,and the treated wastewater can reach the standard discharge.The Ni²⁺with purity greater than 99%can be enriched by elution of PAN-COONa fiber adsorption column.?5?The effects of three coexisting anions SO₄^2-,NO₃^-and Cl^-on the separation and recovery of Cu²⁺and Ni²⁺in mixed simulated electroplating wastewater were investigated.The results showed that no matter static adsorption or dynamic adsorption,the co-existing anions in the wastewater had a great effect on the treatment of Cu²⁺by fiber,but had little effect on the treatment of Ni²⁺.When the anion is SO₄^2-,the treatment effect of Cu²⁺is the best,which is beneficial to the separation and recovery of Cu²⁺and Ni²⁺from the wastewater.