聚丙烯酸铵对重金属离子的吸附效应及在土壤修复上的应用

研究了聚丙烯酸铵对水溶液中重金属离子的吸附效应以及在外源Cd污染的砂质土壤上的应用。结果表明:聚丙烯酸铵在25℃时,30 min即可吸附其吸附总量的50%以上,而在48 h后达到吸附高峰,在120 d的培养过程中其吸附重金属的数量基本稳定。在pH值为4.5～6.5条件下,其吸附量最大,且比较稳定,溶液pH值也发生明显变化;聚丙烯酸铵在吸附重金属离子后,其吸水能力下降显著;聚丙烯酸铵上吸附的重金属的数量随溶液浓度增加而增加,但当浓度超过0.005 mol/L后达到饱和;聚丙烯酸铵对重金属的吸附能力远大于醋酸铵,略高于柠檬酸,而与EDTA相近;在土壤盆栽试验中,聚丙烯酸铵可以显著改善Cd污染条件下的黑麦草的生长,显著降低黑麦草对Cd的吸收,土壤中的水溶性Cd的数量也显著降低;在盆栽条件下,聚丙烯酸铵的合理用量应该在0.1%左右。

Effect of Polyacrylate Polymers on the Absorption of Heavy Metal and Remediation of Artificially Polluted Soil with Cadmium

A experiment in absorption effect of polyacrylate polymer to ions of heavy metal in the water solution was presented in the paper.The results showed that at the temperature of 25 ℃,the absorption to heavy metal of the polyacrylate polymer reached to 50 % of its gross of absorption after 30 mins and to the highest level after 48 h,which was very stable during the time of 120 d.The amount of absorption to the heavy metal was highest and stable in the pH 4.5~6.5.The absorption power of polyacrylate polymer could be remarkably decreased after absorbing ions of heavy metal,especially in the 0.01 and 0.005 M solutions,in which its weight was reduced over 100 times.The amount of heavy metal in the polyacrylate polymer was increased with the increase of content of heavy metal solution and the saturation was attained as the content of solution over 0.005 mol/L.The bond of polyacrylate polymer with ions of heavy metal was much stronger than ammonium acetate,slightly higher than citric acid and close to EDTA.In the potted experiment,the growth of ryegrass was enhanced even in the highest Cd level,the concentration of Cd in ryegrass shoot was significantly decreased,the water-soluble Cd of soil was remarkably reduced as well.The results also indicated the reasonable amount of polyacrylate polmers should be about 0.1%.