CTMAB改性凹凸棒土对水中磺胺吡啶的吸附去除研究

ADSORPTION REMOVAL OF SULFAPYRIDINE FROM WATER BY CTMAB MODIFIED ATTAPULGITE

采用廉价易得的凹凸棒土(ATP)对其用十六烷基三甲基溴化铵(CTMAB)进行改性后,通过间歇吸附实验研究其对水中磺胺吡啶(SPD)的去除性能。采用BET和XRD对吸附剂进行结构表征,结果表明:凹凸棒土的比表面积减小,平均孔径增大,晶体结构未发生明显变化。动力学数据采用拟一级、拟二级和颗粒内扩散模型,等温数据采用Langmuir和Freundlich模型。结果显示,拟二级动力学模型较好地解释了动力学数据,说明吸附过程主要受化学吸附控制。颗粒内扩散模型拟合图表明吸附是1个连续性的分段过程。吸附数据更符合Langmuir模型(测定的Langmuir吸附量为9.9718 mg/g),说明吸附属于单分子层吸附。吸附容量随着SPD初始浓度的增加而增加,随着共存离子和腐植酸浓度的增加而降低。pH值在接近中性到偏碱性范围内吸附效果较好。

The removal of sulfapyridine(SPD)from water was studied by batch adsorption after modification with cetyltrimethyl ammonium bromide(CTMAB)with cheap and readily available attapulgite(ATP).BET and XRD were used to characterize the structure of the adsorbent.The results showed that the specific surface area of attapulgite decreased,the average pore size increased,and the crystal structure did not change significantly.Pseudo-first-order,pseudo-second-order and intra-particle diffusion models were used for kinetic data,and Langmuir and Freundlich models were used for isothermal data.The results show that the pseudo-second-order kinetic model can explain the kinetic data well,indicating that the adsorption process is mainly controlled by chemical adsorption.The fitting diagram of the model shows that the adsorption is a continuous piecewise process.The adsorption data were more consistent with the Langmuir model(Langmuir adsorption amount measured was 9.9718 mg/g),indicating that the adsorption belonged to monolayer adsorption.The adsorption capacity increased with the increase of initial SPD concentration,but decreased with the increase of coexistence ion and humic acid concentration.The adsorption effect is better when the pH value is near neutral to alkaline.