磁性焙烧态锌铝类水滑石吸附腐殖酸与再生

Magnetic Zn/Al-calcined Layered Double Hydroxides Adsorbing Humic Acid from Aqueous Solution and Regeneration

采用化学共沉淀一步法制备了磁性锌铝类水滑石(M·Zn/Al LDHs),并经煅烧得到磁性焙烧态锌铝类水滑石(M·Zn/Al LDO),用以吸附去除水中腐殖酸。文章探讨了M·Zn/Al LDO去除腐殖酸的影响因素,研究了M·Zn/Al LDO吸附腐殖酸的动力学与热力学,考察了吸附腐殖酸后M·Zn/Al LDO焙烧再生的条件。结果表明,当M·Zn/Al LDO投加量<0.2 g/L时腐殖酸去除率随着投加量的增大而增大,腐殖酸的初始浓度增大时吸附量增大但去除率减小。在pH 4~8腐殖酸去除率较高,保持在97%以上。NO3-和F-对去除腐殖酸的影响甚微,而H2PO4-则影响较大。拟二级动力学模型与Langmuir吸附等温线较好地描述吸附过程,吸附过程以物理吸附为主,化学吸附为辅。吸附腐殖酸后的M·Zn/Al LDO通过煅烧恢复焙烧态锌铝类水滑石结构,腐殖酸分解,再生效果良好,且磁性未被破坏。可见,磁性焙烧态锌铝类水滑石是一种高效且有潜在应用前景的去除腐殖酸的水处理材料。

Magnetic Zn/Al layered double hydroxides(M·Zn/Al LDHs)were prepared via one step of chemical co-precipitation method,which was followed by calcination to prepare magnetic Zn/Al-calcined layered double hydroxides(M·Zn/Al LDO)used for the removal of humic acid(HA)from aqueous solution.Influence factors of the removal of humic acid by M·Zn/Al LDO were discussed.The kinetics and thermodynamics of the adsorption of HA on M·Zn/Al LDO were studied.The conditions of the regeneration of M·Zn/Al LDO by calcination after adsorption were investigated.The results showed that the removal efficiency of HA increased with the increase of M·Zn/Al LDO dosage when the dosage was less than 0.2 g×L-1.The adsorption capacity increased with increasing HA initial concentration,but the removal efficiency decreased.The HA removal efficiency was high in p H range of 4~8,maintaining over 97%.NO3-and F-has little influence but H2PO4-had a great effect on the HA removal.The adsorption process was well fitted by the pseudo-second-order kinetic model and Langmuir isothermal model,and chemical adsorption was primary and physical adsorption was complementary.M·Zn/Al LDO adsorbing HA recovered the structure of magnetic Zn/Al-calcined layered double hydroxides by calcination,in which HA decomposed.The regeneration effect was good but its magnetism was not damaged.The magnetic Zn/Al-calcined layered double hydroxides was a highly effective material which had potential application prospect for HA removal in water treatment.