腐殖酸对改性聚乙烯亚胺去除水中Cu(Ⅱ)的影响

Effects of humic acid on Cu(Ⅱ) removal from aqueous solution using modified polyethyleneimine

采用二硫化碳和氢氧化钠对聚乙烯亚胺进行改性,制备出一种新型高分子絮凝剂聚乙烯亚胺基黄原酸钠(PEX).以含Cu(Ⅱ)水样为处理对象,研究了腐殖酸(HA)的存在对改性聚乙烯亚胺(PEX)去除水样中Cu(Ⅱ)性能的影响,探讨了HA共存时PEX除Cu(Ⅱ)机理.结果表明,HA的存在对PEX去除Cu(Ⅱ)表现出一定的抑制作用,Cu(Ⅱ)去除率随着体系中共存HA浓度的增大而降低,随着PEX投加量的增加而升高,随着pH值的升高而升高;当PEX投加量增加到100 mg·L^(-1)以上或体系pH值升高到6.0时,可消除HA的抑制影响,Cu(Ⅱ)的最高去除率均可达到100%.絮体的Zeta电位随着共存HA浓度的增加而升高,PEX除Cu(Ⅱ)的絮凝作用机理以吸附架桥为主;PEX高分子链上的二硫代羧基与Cu(Ⅱ)发生了螯合沉淀反应,PEX对共存体系中Cu(Ⅱ)和HA均具有一定的去除效果.

A novel macromolecule flocculant, called polyethyleneimine-sodium xanthogenate(PEX), was prepared by modifying polyethyleneimine with carbon disulfide and sodium hydroxide, and it was applied in the treatment of water sample containing Cu(Ⅱ) ions. The effect of HA on the removal performance of Cu(Ⅱ) with PEX was studied, and the mechanism that Cu(Ⅱ) was removed by PEX with the coexistence of HA was also investigated. The results showed that the coexistence of HA would inhibit the removal of Cu(Ⅱ). The removal efficiency of Cu(Ⅱ) by PEX decreased with the increase of HA concentration, and increased with the increase of the dosage of PEX or the initial pH in the mixed system. However, the inhibiting effect of HA could be eliminated when the dosage of PEX was more than 100 mg·L-1 or the initial pH was 6.0, and reaching the highest removal rate of Cu(Ⅱ) at 100%. The zeta potential of floc increased with the increase of HA concentration, and the flocculation mechanism for the removal of Cu(Ⅱ) by PEX was mainly reflected in the adsorption bridging action. Moreover, the reaction of chelation precipitation existed between dithiocarboxylic acid groups of PEX and Cu(Ⅱ). In addition, Cu(Ⅱ) and HA could be removed simultaneously by PEX in the coexistence system.