聚天冬氨酸对土壤吸附、解吸汞的机制研究

Mechanism of Adsorption and Desorption of Mercury on Soil by Polyaspartic Acid

为揭示土壤中添加聚天冬氨酸(PASP)后其对汞的吸附、解吸过程,探究了不同PASP用量对土壤吸附解吸汞的机制及有机质、pH、汞初始浓度等因素的影响。结果表明,PASP可显著抑制土壤对汞的吸附,促进土壤对汞的解吸,在PASP用量为300 mg时,其吸附量、解吸量分别是未添加PASP时的0.68、27倍,有机质与PASP之间在土壤吸附汞时表现为拮抗作用,在土壤解吸汞时表现为协同作用,在较宽pH范围(4.0~7.0)和不同汞浓度(5~200 mg/L)下,PASP均能抑制土壤对汞的吸附,PASP作用于整个吸附进程,土壤对汞的吸附特征符合Langmuir、Freundlich方程和准二级动力学方程,而PASP的存在均使其特征方程偏离,原土和去除有机质的土壤对汞的最大吸附量(qm)分别为2.1和2.0 mg/g,比未添加PASP的处理分别下降了65.47%和12.94%。本研究为PASP应用于汞污染土壤的修复奠定了研究基础。

In order to reveal the adsorption and desorption characteristics of mercury on soil with the presence of polyaspartic acid( PASP),the adsorption and desorption mechanisms of mercury on soil with various dosage of polyaspartic acid( PASP) were identified. Besides,the effects of soil organic matter,pH and initial concentration of mercury on the adsorption process were characterized.The results showed that PASP could inhibit the adsorption process and facilitate the desorption process of mercury on soil. When the dosage of PASP was 300 mg,the adsorption and desorption capacity were calculated to be 0. 68 and 27 times greater than that of the treatment without PASP,respectively. Soil organic matter plays an antagonistic role in the adsorption process and a synergistic effect in the desorption process. Under a wide pH range( 4. 0-7. 0) and different mercury concentrations( 5-200 mg/L),PASP can inhibit the adsorption of mercury on soil in the whole adsorption process. The Langmuir,Freundlich,and pseudo-second-order kinetic equation can well describe the adsorption process. The presence of PASP made the fitting results deviated. The maximum adsorption capacity( qm) of the raw soil and the organic matter removed soil were 2. 1 and 2. 0 mg/g respectively,which decreased by 65. 47% and12. 94% compared with that without PASP. This study lays the foundation for the application of PASP in the remediation of mercury contaminated soil.