重金属絮凝剂DTMPAM去除水中Cu2+和EDTA-Cu的性能

以聚丙烯酰胺、甲醛、二硫化碳、氢氧化钠为原料,制备出新型重金属絮凝剂二硫代羧基化羟甲基聚丙烯酰胺(DTMPAM).分别以含Cu~(2+)单一水样及含Cu~(2+)、EDTA的混合水样为考察对象,研究DTMPAM在单一和混合体系中对Cu~(2+)的去除性能.结果表明,单一体系中DTMPAM对Cu~(2+)有着良好的去除效果,当水样pH值为2.0～6.0时,Cu~(2+)的最高去除率在93.85%～97.49%之间.EDTA对DTMPAM除Cu~(2+)呈抑制作用,随着体系pH值的降低,这种抑制作用减弱;高pH值体系中,随着EDTA浓度的增大,抑制作用增强;在混合体系中,EDTA与DTMPAM存在配位竞争作用,高pH值体系中EDTA的配位竞争作用占主要优势.在单一体系和混合体系中螯合絮体DTMPAM-Cu的分形维数与Cu~(2+)的去除率均有显著的正相关性,即絮体分形维数越大,相对应的Cu~(2+)去除率越高.

The performance of Cu2+ and EDTA-Cu removal in aqueous solutions with heavy metal flocculant DTMPAM

A novel heavy metal flocculant, dithiocarboxyl hydroxymethy-polyacrylamide (DTMPAM), was prepared by using polyacrylamide, formaldehyde, carbon disulfide and sodium hydroxide as raw materials. The removal performance of Cu²⁺ was studied with the water containing Cu²⁺ with/without EDTA. The results show that DTMPAM had good removal efficiency for Cu²⁺. The highest removal rate of Cu²⁺ was between 93.85% and 97.49% at pH 2.0 to 6.0. EDTA had an inhibiting effect on the removal of Cu²⁺ by coagulation with DTMPAM, and the inhibiting effect was weakened with the decrease of pH. When Cu²⁺ and EDTA co-existed, EDTA had the competition with DTMPAM, and more dominant at higher pH. DTMPAM-Cu had good positive correlation with the removal rate of Cu²⁺ in the single or mixed system, that is, the fractal dimension of flocs was the larger, and the removal rate of Cu²⁺ was the higher.