改性石英砂吸附水中四环素的机制研究

通过使用Piranha溶液和KH-550溶液对普通石英砂(NAT)进行改性处理,得到亲水改性石英砂(HYL)和疏水改性石英砂(HYB),对3种石英砂进行表面性质表征并考察其吸附四环素的性能和影响因素。结果表明,HYL和HYB的比表面积均大于NAT,且亲、疏水性得到改善。HYL、HYB和NAT对四环素的饱和吸附量分别为25. 60、7. 67和11. 94 mg/kg。伪一级动力学模型和伪二级动力学模型对3种石英砂吸附四环素过程的拟合程度均较好(R^2> 0. 97); Langmuir和Freundlich吸附等温模型拟合程度较好(R^2> 0. 97),Tempkin模型拟合相关系数R^2=0. 74～0. 84。HYL在pH值=6. 0且无阳离子作用下吸附效果最佳; HYB在pH值=10. 0时吸附效果较好,且Ca²⁺的存在使吸附量大量增加; NAT在p H值=10. 0、无阳离子作用下吸附效果最佳。经分析,HYL吸附四环素主要为化学吸附并伴有一定程度的静电作用,HYB主要依靠表面吸附并带有离子交换作用,NAT主要以化学吸附为主。

Adsorption Mechanism of Tetracycline by Modified Quartz Sand

Normal quartz sand( NAT) was modified by Piranha solution and KH-550 solution to obtain hydrophilic modified quartz sand( HYL) and hydrophobic modified quartz sand( HYB). The surface properties were characterized,and the adsorption performance of tetracycline and the influence factors were investigated. The results showed that the specific surface area of HYL or HYB was greater than that of NAT,and the hydrophilicity and hydrophobicity were improved. The saturated adsorption capacities of tetracycline by HYL,HYB,and NAT were 25. 60 mg/kg,7. 67 mg/kg,and 11. 94 mg/kg,respectively. The pseudo-first-order kinetics model and the pseudo-second-order kinetics model both showed high goodness of fit to the adsorption of tetracycline( R^2> 0. 97),as well as the Langmuir and Freundlich adsorption isotherm models( R2> 0. 97). Tempkin model had correlation coefficient R2=0. 74-0. 84. HYL showed the best adsorption ability at pH = 6. 0 without cation. HYB demonstrated good adsorption ability at pH = 10. 0,and the presence of Ca2+ increased the adsorption amount. NAT had the best adsorption effect at pH = 10. 0 without cation. Analysis revealed that the adsorption of tetracycline by HYL was mainly chemisorption and accompanied by a degree of electrostatic interaction,the adsorption by HYB mainly depended on surface adsorption and ion exchange,and the adsorption by NAT was mainly based on chemical adsorption.