摘要
用平衡液吸附和Ca(NO3)2溶液的解吸法,对棕土在pH3-6.5,汞浓度0.2-8mg·kg-1的吸附-解吸动力学进行了研究,以阐明pH和初始浓度对汞有效性的影响。结果表明,pH6.5,浓度8mg·kg-1条件下,60min即可达到汞最大吸附量的93%;10000min达最大解吸量的78.8%。解吸汞占吸附汞的比例随pH升高而升高,在浓度2mg·kg-1,pH3-6.5下,棕土解吸汞占吸附汞的比例为11%-37.4%。Freundlich方程为描述汞吸附-解吸动力学特征的最优模型,其次为Elovich方程。模拟的最大吸附量达84.3mg·kg-1,在此以下,汞的吸附容量随外加汞浓度、时间的递增而升高。解吸速率随初始浓度增加而增加,随解吸时间的延长不断降低。这些结果表明,pH和外加汞浓度影响汞在棕土中的吸附-解吸动力学特征,从而影响在土壤介质中的迁移。
Soils are a major sink for mercury （Hg）, which can be absorbed and bioaccumulated by plants and animals and eventually consumed by humans. The study is to examine the sorption-desorption processes of mercury from umber at various experimental conditions, us ing isothermal equilibrium adsorption method and continuing desorption method of dilute Ca（NO3）2 solution. The results showed that at pH 6.5, 8 mg·kg^-l Hg^2＋ concentration, Hg was adsorbed-desorbed fast, which obtained 93% of the maximum adsorption amount within 60 min, 78.8% of the maximum desorption amount within 10 000 min. The proportion of mercury desorption to adsorption increased with pH. At pH 3～6.5, the ratio of desorption to sorption of mercury in umber was 11%～37.4% with average 21%. Compared with Elovich, Freundlich equation was the best model for mercury sorption and desorption. The maximum adsorption capacity was over 84.3 mg·kg^-1. Before saturation, Hg^2＋ adsorption capacity showed a linear response to the concentration of spiked Hg^2＋ and reaction time, specific adsorption predominated. The desorption rate of Hg^2＋ increased with the higher initial concentration of Hg^2＋, and decreased with the increasing desorption time. The results suggested that mercury movement may be affected by pH and Hg^2＋ concentration.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2008年第2期579-582,共4页
Journal of Agro-Environment Science
基金
沈阳市细河流域生态地球化学评价项目
国家自然科学基金项目(20477029)
关键词
汞
吸附-解吸
棕土
动力学
mercury
adsorption-desorption
umber
kinetics
