采用批平衡吸附试验研究了诺氟沙星在河南封丘潮土、江西鹰潭红壤、苏南常熟水稻土和南京黄棕壤等4种土壤中的吸附热力学和动力学行为。结果表明,诺氟沙星在4种供试土壤的Fruendlieh吸附参数值墨随温度升高(15℃、25℃和35℃)而减小;在低土壤溶液pH下诺氟沙星的吸附焓变值△H°较大,而高pH下则较小。用氢氧化钠或盐酸溶液分别调节红壤pH从5.20到8.00,水稻土pH从6.14至8.20,黄棕壤pH从7.78至5.80和潮土pH从8.08至5.90,其△H°与pH之间的关系同样呈现如上关系。这证实4种土壤对诺氟沙星的吸附作用力差异较大。低pH(5.20-6.14)下,诺氟沙星在土壤中的吸附以离子交换和氢键等为主;而高pH(7.78-8.20)下,则以相对较弱的范德华力、疏水作用等为主。诺氟沙星的土壤吸附过程迅速达到平衡,其反应动力学用Elovich方程和双常数方程拟合结果最好。
Batch equilibrium experiments (OECD Guideline 106) were conducted to study thermodynamics and ki- netics of norfloxaein (NOR) adsorption in four kinds of soils, namely Ustic Cambosols collected from Fengqiu of Henan,, Ali-Perudic Ferrosols collected from Yingtan of Jiangxi, Gleyic-Stagnic Anthrosols collected from Changshu and Udic Argosols collected from Nanjing of Jiangsu. Results show that mechanism of NOR sorpfion in the four tested soils is controlled to a certain extent by pH of soil solution. With rising temperature (288K,298K and 308K), Fruendlieh coefficients (Kf) of NOR sorption decreased in all the four soils and the change in enthalpy (△H°) was significant at low soil pH and relatively slight at high soil pH ,which was coincident with the results obtained from the four soils with pH adjusted with sodium hydroxide or hydrochloric acid solution. Forces of NOR sorption in the four soils varied greatly with pH, so that different sorption behaviors were observed. At low pH (5.20-6.14 ) , ion exchange and hydrogen bond predominated NOR sorption process; while at high pH (7.78- 8.20) ,weaker Van der waals interaction and Hydrophohie bond were the control factors. Moreover,NOR sorption in the soils reached equilibrium quickly and the kinetics of NOR adsorption was best described by Elovich model and two-constant equation.