二氧化硅微球包埋羧甲基壳聚糖回收稀土镧离子

Recovery of Lanthanum(Ⅲ) Ions by Carboxymethyl Chitosan Entrapped by Silica Microspheres

解决离子吸附型稀土矿低浓度浸出液和淋滤水中稀土的截留和回收难题十分必要。以稀土镧离子(La(Ⅲ))为代表,采用包埋羧甲基壳聚糖的二氧化硅微球复合吸附剂(SiO_2/CMCH)从低浓度模拟稀土料液中回收La(Ⅲ),并系统研究了溶液pH、La(Ⅲ)浓度、吸附时间、NaNO_3浓度等对La(Ⅲ)吸附量的影响。结果表明,La(Ⅲ)吸附遵循Langmuir等温吸附模型和准二级动力学模型。在308 K的HCl体系中,SiO_2/CMCH对La(Ⅲ)的饱和吸附容量为23.26 mg/g干吸附剂或190.66 mg/g CMCH。吸附为阳离子交换机理,-NH2具有显著的协同配位效应。稀盐酸可以实现对负载在SiO_2/CMCH中La(Ⅲ)的完全解吸,且吸附剂可循环再生。

It is necessary to solve the problem of interception and recovery of rare earth in low - concentration leaching water. Taking lanthanum ions as the object, this work reported the recovery of lanthanum（Ⅲ） ions from aqueous solution by earboxymethyl chitosan adsorbents entrapped by silica （SiOJCMCH）. The effects of equilibrium pH, contact time, initial concentrations of La（Ⅲ） and NaNO3 on the adsorption were investigated. It was found that adsorption kinetics and i- sotherm could be described by the pseudo -second -order model and Langmuir equation. The La（Ⅲ） adsorption amounts calculated by Langmuir equation were 23.26 mg/g dry adsorbent or 190.66 mg/g CMCH at 308 K. The adsorption mechanism was cation exchange, and - NH2 had significant synergistic effect. The dilute hydrochloric acid could completely desorb La （Ⅲ） in SiO2/ CMCH, and the adsorbent was recycled.