Effect of Initial Concentration on Adsorption-Desorption Characteristics and Desorption Hysteresis of Hexachlorobenzene in Soils  

作　　者：GAO Hong-Jian JIANG Xin 

机构地区：[1]School of Resources and Environmental Science, Anhui Agricultural University, Hefei 230036 (China) [2]State Key Lab of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China)

出　　处：《Pedosphere》2010年第1期104-110,共7页土壤圈（英文版）

基　　金：Project supported by the Open foundation of the State Key Lab of Soil and Sustainable Agriculture, Institute of SoilScience, Chinese Academy of Sciences (No. 0812000037);the Scientific Research Starting Foundation for the ReturnedOverseas Chinese Scholars, Ministry of Education, China (No. 20091001);the National Science and Technology PillarProgram During the 11th Five-Year Period of China (No. 2009BADA6B04)

摘　　要：Adsorption and desorption are important processes that influence the transport, transformation, and bioavailability of hexachlorobenzene (HCB) in soils. To examine the adsorption-desorption characteristics of HCB, equilibrium batch experiments were carried out using two soils (red soil and paddy soil) with different initial HCB concentrations (0.25, 0.50, 0.75, 1.00, 1.50, 2.50, 3.50, and 5.00 mg L-1 ) by using 0.01 mol L-1 calcium chloride as the background solution. The successive desorption experiments (48, 96, 144, 192, and 240 h) were conducted after each adsorption equilibrium experiment. The results revealed that adsorption and desorption isotherms of HCB on two soils were nonlinear, which can be best described by the Freundlich equation with the square of the correlation coefficient (r 2 ) ranging from 0.97 to 0.99. Desorption of HCB from the two soils exhibited hysteresis at all HCB concentrations because the Freundlich desorption coefficients were always higher than the Freundlich adsorption coefficients. The hysteretic effect was enhanced with increasing initial HCB concentration, and positive hysteresis was observed at different concentrations.Adsorption and desorption are important processes that influence the transport, transformation, and bioavailability of hexachlorobenzene （HCB） in soils. To examine the adsorption-desorption characteristics of HCB, equilibrium batch experiments were carried out using two soils （red soil and paddy soil） with different initial HCB concentrations （0.25, 0.50, 0.75, 1.00, 1.50, 2.50, 3.50, and 5.00 mg L^- 1） by using 0.01 mol L^-1 calcium chloride as the background solution. The successive desorption experiments （48, 96, 144, 192, and 240 h） were conducted after each adsorption equilibrium experiment. The results revealed that adsorption and desorption isotherms of HCB on two soils were nonlinear, which can be best described by the Freundlich equation with the square of the correlation coefficient （r^2） ranging from 0.97 to 0.99. Desorption of HCB from the two soils exhibited hysteresis at all HCB concentrations because the Freundlich desorption coefficients were always higher than the Freundlich adsorption coefficients. The hysteretic effect was enhanced with increasing initial HCB concentration, and positive hysteresis was observed at different concentrations.

关 键 词：Freundlich equation sorption coefficients sorption isotherms 

分 类 号：X511[环境科学与工程—环境工程] O647.3[理学—物理化学]