壳聚糖对污染土壤中吸附态Pb(Ⅱ)的解吸作用

Enhanced extraction of chitosan for lead (Ⅱ) from contaminated soil

土壤中重金属的吸附-解吸直接影响重金属在土壤及其生态环境中的形态转化、迁移和归趋。利用螯合剂促进普通植物富集吸收土壤中重金属是一种新的土壤组合修复技术,向污染土壤中施用螯合剂可增加土壤溶液金属的浓度和活度,有利于金属到根部而被植物吸收。通过吸附等温实验研究了壳聚糖对污染土壤中铅的解吸作用。将壳聚糖提取液加入含Pb土壤中结果表明,壳聚糖螯合剂能提高土壤中吸附态铅的解吸效率,增加解吸溶液中Pb2+的浓度。壳聚糖对污染土壤中铅的解吸作用随着壳聚糖加入量的增大而增大,用浓度为0.4g·L-1的90%脱乙酰度壳聚糖做提取液,提取液pH=3,提取平衡时间10h达到最高提取率32.4%,该吸附过程遵从Langmuir等温吸附方程;土柱淋溶实验表明壳聚糖对污染土壤中Pb2+的提取率为27.4%。研究结果为铅在环境中的迁移转化和治理技术等方面的实际应用提供有价值的参考。

With the heavy metal contaminated soil increasing, the requirement ofremediation and control technology becomes urgent. With the heavy metal contaminated soil increasing, the requirement ofremediation and control technology becomes urgent. Although non- metallic mines have been used widely as soil amender, there are few reports for remedy heavy metal contaminated soil especially for lead（ Ⅱ ） contaminated soil. The absorption- desorption of heavy metals in soil impact directly the form of transformation, migration and fate of heavy metals in soil and ecological environment. It is one kind of new soil combination remediation and control technology using the chelating agent to promote the ordinary plant concentrating the heavy metal in the absorption soil. Apply the chelating agent to the pollution soil could increase the concentrate of the metallic ion in soil solution and advantageous in the metallic ion to the root by the plant absorption. The effectiveness adsorption isotherm experiments were conducted to investigate the effect of of chitosan in removing pb2＋from the artificiall contaminated soil. Chitosan additive enhanced the Pb（ Ⅱ ） extraction effectively. At a pH of 3, 0.4 mg.L^-1 chitosan of 90% the degree of deacetylation, adsorption equilibrium time is about 10 h removed 32.4% of Pb2＋ from the 0.4 mg.gl of Pb2＋soils ample. The adsorption isotherm followed Langmuir isotherm equation. The flushing experiment indicates that the soil available lead （Ⅱ） has been reduced less than 27.4%. The results provide the valuable reference for the environment migration of lead and s0il pollution control technology.