Selective removal of La(III) from mine tailwater using porous titanium phosphate monolith: Adsorption behavior and mechanism

Abstract

The separation of rare earth elements from mine tailwater has received extensive attention because of the harm to the surrounding environment caused by the low concentrations of rare earth elements in tailwater produced by rare earth mining, and the high demand for rare earth elements in modern society. In this study, a porous titanium phosphate (TP) monolith material was prepared via a sol-gel process accompanied by a phase separation method for the adsorption of La(III) in mine tailwater. The results show that the adsorbent had a stable co-continuous porous skeletal structure. The adsorption performance of the adsorbent was almost unaffected when the solution pH was greater than 2. The PSO kinetic model and Langmuir isotherm model fit the experimental data well, and the maximum adsorption capacity at 30 °C was 253.97 mg·g−1. The TP monolith material exhibited excellent properties such as easy solid-liquid separation, good acid resistance and high adsorption capacity. In addition, the porous TP monolith had not only a certain selectivity for La(III), but also excellent adsorption-desorption and regeneration properties, which promote the application of TP monolith in the recovery of La(III) in actual wastewater. Finally, it was inferred from the mechanistic analysis that the phosphate groups on the material surface played a key role in the adsorption of La(III) by TP monolith materials.