有机改性对凹凸棒黏土吸附四环素类抗生素的影响

Effects of the Organic Modification on the Attapulgite Adsorption for Tetracycline Antibiotics

采用OECD guideline 106批量平衡吸附法研究四环素类抗生素在十六烷基三甲基溴化铵改性凹凸棒黏土(CTAB-ATP)上的吸附作用,并考察了溶液pH、吸附剂的投加量、离子强度对吸附过程的影响。结果表明,CTAB-ATP对四环素、土霉素、金霉素3种四环素类抗生素的吸附容量随着溶液pH的增加而增加;随着吸附剂投加量的增大而减小;随着离子强度的增加呈现缓慢减小的趋势。CTAB-ATP对四环素、土霉素、金霉素的吸附过程均符合准二级动力学模型(r>0.998),吸附等温线较好地符合Langmuir等温式。有机改性凹凸棒黏土的疏水性增强,提高了对有机污染物的吸附能力,其沉降性能良好,这使其作为一种吸附剂用于实际抗生素废水的处理成为可能。

The OECD Guideline 106 batch adsorption method was employed to reveal the adsorption function of three tetracycline antibiotics onto attapulgite modified with cetyltrimethylammonium bromide（CTAB-ATP）. And the effects of pH,the dosage of adsorbent and ionic concentrations on the adsorption process were also discussed. The results showed that adsorption capacity of CTAB-ATP for three tetracycline antibiotics（tetracycline,oxytetracycline and chlorotetracycline） increased with the increase of pH,and decreased with the increase of adsorbent concentration. Moreover,with the increase of Ca^（2＋） concentration,the adsorption capacity showed a slowly decrease trends. The adsorption process of CTAB-ATP for three tetracycline antibiotics could be described by pseudo-second-order kinetics（r〉0.998）. The adsorption isotherms were well fitted by Langmuir isotherm model. With the hydrophobicity increase of CTAB-ATP,its adsorption capacity for organic pollutants was enhanced. Furthermore,the sedimentation of organo-attapulgite was better. Therefore,the good adsorbability and settleability of organo-attapulgite make it a potential adsorbent in antibiotics effluent treatment.