YE Cai, FAN Li, SUN Rongguo, GAO Yue
(School of Chemistry and Material Guizhou Normal University, Guiyang 550025,China)

Abstract: 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 adsorption process and a synergistic effect in 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% and 12.94% compared with that without PASP. This study lays the foundation for the application of PASP in the remediation of mercury contaminated soil.

Key word: polyaspartic acid; mercury; adsorption and desorption; mechanism

EARTH AND ENVIRONMENT Vol.49, No.5, Tot No.343, 2021, Page 520-528