二硫代羧基化羟甲基聚丙烯酰胺与Cu2+的螯合稳定性

以聚丙烯酰胺、甲醛、氢氧化钠、二硫化碳为原料制备了重金属螯合絮凝剂二硫代羧基化羟甲基聚丙烯酰胺（DTMPAM），采用紫外分光光度法测定了DTMPAM与Cu²⁺形成的螯合物在不同Cu²⁺浓度、二硫代羧基（—CSS^-）浓度、不同pH值下的紫外吸收光谱，确定了螯合物的配位比，考察了螯合物DTMPAM-Cu在不同pH值、不同—CSS^-浓度下的稳定性，并计算了其稳定常数.结果表明，DTMPAM在207和226nm处出现最大吸收峰，而螯合物DTMPAM-Cu分别在220和260nm处出现最大吸收峰，最大吸收峰发生红移.在不同的—CSS^-（3.0×10^-5~6.0×10^-5mol/L）浓度和pH值（3.0~9.0）下，DTMPAM中的—CSS^-与Cu²⁺的螯合比均为2：1；当—CSS^-浓度为3.0×10^-5~6.0×10^-5mol/L时，DTMPAM-Cu的螯合稳定常数对数值lgβ₂在10.5725~11.4473之间，随着—CSS^-浓度增大，螯合稳定常数略有减小.不同pH值下，DTMPAM-Cu的螯合稳定常数各不相同，当体系pH值为3.0~5.0时，随着pH值的升高，DTMPAM-Cu的稳定常数逐渐升高，当pH值为6.0~9.0时，DTMPAM-Cu的稳定常数整体上略有所降低.

Chelating stability of dithiocarboxyl hydroxymethy-polyacrylamide with Cu2+

A heavy metal floccutant dithiocarboxyl hydroxymethy-polyacrylamide (DTMPAM) was prepared by using polyacrylamide, formaldehyde, sodium hydroxide and carbon disulfide as raw materials. The absorption spectra of the chelate formed between DTMPAM and Cu²⁺ was determined by UV spectrophotometry under different Cu²⁺ concentrations, dithiocarboxyl groups (—CSS^-) concentrations and pH values. The coordination ratio of the chelate was discussed, the stability of the chelate DTMPAM-Cu at different pH values and different —CSS^- concentrations was investigated, and its stability constant was calculated. The results showed that the maximum absorption peaks of DTMPAM appeared at 207 and 226nm, but the maximum absorption peaks of chelate DTMPAM-Cu appeard at 220 and 260nm, respectively. Compared with the absorption peaks of DTMPAM, the maximum absorption peaks of chelate DTMPAM-Cu occurred red shifting. Under different —CSS^- concentrations (3.0×10^-5~6.0×10^-5mol/L) and pH values (3.0~9.0), the chelating ratio of DTMPAM and Cu²⁺ was 2:1. When the —CSS^- concentration was 3.0x10^-5~6.0×10^-5mol/L, the chelation stability constant lgβ₂ of DTMPAM-Cu was between 10.5725~11.4473; with the increase of —CSS^- concentration, the chelating stability constant decreased slightly. At different pH values, the chelation stability constants of DTMPAM-Cu were different, when the pH value was 3.0~5.0, the stability constant of DTMPAM-Cu increased gradually with the increase of pH value. When the pH value was 6.0~9.0, the stability constant of DTMPAM-Cu decreased slightly.