聚合物强化超滤过程处理含Hg~(2+)废水

研究聚丙烯酸钠(PAASS)与Hg2+络合反应动力学,当PAASS大量过剩及pH值恒为5时,络合反应达到平衡时间为25 m in,反应行为可用拟一级速率方程描述。测定PAASS对Hg2+络合能力,pH=5时每mg PAASS络合容量为1.0 mg。考察pH值、盐浓度和竞争络合剂对Hg2+截留系数的影响,可得:pH=5及负载比LR=1时适宜截留Hg2+;当C l-和SO42-浓度增大时,Hg2+截留系数逐渐降低;酒石酸钠和三乙醇胺不干扰PAASS与Hg2+的络合。进一步研究超滤浓缩行为,结果表明:当pH=5,PAASS及Hg2+初始质量浓度均为100 mg/L时,原料液浓缩15倍,膜通量仅衰减15.0%,浓缩液及渗透液汞质量浓度分别为1499.6,0.03 mg/L。

Treatment of wastewater containing Hg2+by polymer-enhanced ultrafiltration

The kinetics of complexation reaction for polyacrylic acid sodium salt(PAASS) and Hg2 was investigated under a large excess of PAASS and at a constant pH=5.It took 25 min for the reaction to reach the equilibrium,and the reaction kinetics could be described by a pseudo-first-order equation.When pH=5,the binding capacity for PAASS to Hg2 was 1.0 mg.The effects of pH values,salt concentrations and competitive complexing agents on Hg2 rejection coefficients were investigated.The results show that Hg2 is retained effectively when pH=5 and loading ratio LR=1;the metal rejection coefficients decrease gradually with the increase of Cl-and SO2-4 concentrations,and the competitive complexing agents(tartrate sodium and triethanolamine) do not affect the complexation reaction of PAASS to Hg2 .The effect of volume concentration factor on the behavior of ultrafiltration was examined further.The results indicate that under the conditions of pH=5,the initial mass concentrations of PAASS and Hg2 are both 100 mg/L,volume concentration factor reaches 15 times,the membrane flux declines only by 15.0%,and Hg2 mass concentrations in the retentate and permeate are 1499.6 and 0.03 mg/L,respectively.