干旱区绿洲土壤对磺胺甲恶唑的吸附特性及影响因素

Adsorption characteristics and influencing factors of sulfamethoxazole in arid oasis soil

采用批量吸附法研究了磺胺甲恶唑在干旱区绿洲土壤上的吸附动力学、热力学及pH、腐殖酸浓度、Na+强度、Cu2+质量浓度等因素对吸附的影响.结果表明:磺胺甲恶唑在绿洲土壤上的吸附动力学符合准二级动力学模型;初始质量浓度为10、20 mg/L时,磺胺甲恶唑在干旱区绿洲土壤中的最大吸附量分别为9.810×10-5、1.992×10-4.Freundlich方程能较好地拟合吸附等温数据,吸附反应为放热反应,吸附过程主要为物理反应.pH、Na+强度及共存Cu2+影响吸附过程.当溶液初始pH大于磺胺甲恶唑电离平衡常数的负对数为5.7时,土壤对磺胺甲恶唑的吸附量由2.336×10-4下降至1.905×10-4;腐殖酸浓度的增加不利于土壤对磺胺甲恶唑的吸附;磺胺甲恶唑在土壤中的吸附量随着溶液中Na+质量浓度的增加而降低,随Cu2+质量浓度的增高而增大.

The adsorption kinetics,thermodynamics and the effects of pH,humic acid concentration,Na+concentration and Cu2+concentration on the adsorption of sulfamethoxazole in arid oasis soil were investigated by the batch adsorption method.The results suggested that the adsorption kinetics of sulfamethoxazole in arid oasis soil fitted the pseudo-second-order kinetics model.When the initial concentration was 10 and 20 mg/L,the maximum adsorption amount of sulfamethoxazole was 9.810×10-5,1.992×10-4 respectively.The Freundlich equation could fit better the adsorption isotherm data,the adsorption reaction was an exothermic reaction and the adsorption process was mainly physical adsorption.The pH,Na+strength and coexisting Cu2+affected the adsorption process.When the initial pH of solution was higher than pKa 5.7 of sulfamethoxazole,the adsorption amount of sulfamethoxazole in soil decreased from 2.336×10-4 to 1.905×10-4.The increase of humic acid concentration was not conducive to the adsorption of sulfamethoxazole in soil.The adsorption capacity of sulfamethoxazole in soil decreased with the increase of the concentration of Na+in the solution,but increased with the increase of the concentration of Cu2+.