Experiment of PAAS Complexation-UF Process for Mn2+and Co2+Separation in Battery Wastewater
The effects of complexation-UF process on the interception,separation,and complexation competition of Mn2+and Co2+in aqueous solutions were investigated using sodium polyacrylate(PAAS)and polyether sulfone(PES)hollow fiber ultrafiltration(UF)membranes.The results of the experiments of single metal ions indicated that with the increases of m(P)/m(M)(the mass ratio of PAAS to metal ions)and pH,the interception of Mn2+and Co2+gradually increased.With increasing the temperature,the interception of Mn2+and Co2+first increased and then decreased.The maximum retention rates of Mn2+and Co2+were at the temperature of 20 ℃and 25 ℃,respectively.At the optimum operating conditions of pH value=5,m(P)/m(M)=4,and 20 ℃,the maximum separation rate was 64.70％,at which point the complexation competition effect was the strongest.The addition of NaCl weakened the competitive complexing ability of metal ions,which was not conducive to the separation of Mn2+and Co2+.The mixed metal ion experiments showed that the separation rate was 57.41％at optimum operating conditions.Fourier transform infrared(FTIR)results indicated that both Mn2+and Co2+could be complexed with PAAS.However,Mn2+and Co2+had different complexing affinities towards PAAS owing to the differences in hydration heat and electronegativity.Under the same solution environment,Mn2+preferentially complexed with PAAS.
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