镧改性膨润土对磷吸附特性、机理与影响因素

Adsorption Performance, Mechanism and Influence Factors of Phosphorus on Phoslock^(®)

文章研究了镧改性膨润土(锁磷剂,Phoslock^(®))对水溶液中磷的吸附特征,通过动力学和热力学方程对吸附过程进行了拟合,用X射线衍射分析和磷分级方法考察了吸附后磷形态变化,并探索了粒径和pH对吸附特征的影响。结果表明:锁磷剂对磷的吸附过程可用伪二级动力学和Langmuir方程很好地拟合,理论饱和吸附量为12.02 mg/g。吸附的磷主要以稳定的HCl-P形态存在,占总可提取形态的97.80%~99.01%,且不易释放。吸附后无晶体生成,矿物成分与膨润土相似,主要为蒙脱石和石英。粒径可影响吸附速率,但对吸附容量影响较小。pH为2.96~11.03时,吸附量为7.63~11.45 mg/g,低pH促进磷的吸附;pH为2.81~11.09时,解吸率≤11.34%,解吸量随pH的升高而升高。该研究为锁磷剂在湖泊内源磷治理中的应用提供了理论依据。

The adsorption performance of phosphorus(P) in aqueous solution on lanthanum modified bentonite(Phoslock^(®))is studied. The adsorption process is fitted by kinetic and thermodynamic equations. P forms after adsorption are investigated by X-ray diffraction(XRD) and P fractionation methods. The effects of particle size and pH on the adsorption are also explored. The results show that the adsorption can be well fitted by pseudo-second-order kinetic and Langmuir equations,and the theoretical adsorption capacity is 12.02 mg/g. The adsorbed P exists mainly in stable HCl-P form, accounting for 97.80%~99.01% of the total extractable forms, which is not easy to release. After adsorption, there is no crystal formation, and the mineral composition is similar to that of bentonite, mainly montmorillonite and quartz. The particle size can affect adsorption rate, but has little effect on adsorption capacity. When the pH is 2.96~11.03, the adsorption capacity is 7.63~11.45 mg/g,and low p H promotes the adsorption;the desorption percentage is less than 11.34% when the pH is 2.81~11.09, and the desorption capacity increases with the increase of pH. The study provides a theoretical basis for the application of Phoslock^(®) in lake internal P control.