Selective and efficient removal of lanthanum ion in aqueous solution by P-doped porous carbon

Abstract

Adsorption and selective adsorption are effective means of separating rare earths (REs) from aqueous solutions and reducing heavy metal contamination. In this work, bagasse was used as carbon source and phytic acid as phosphorus source and activator, and a simple synthesis strategy was applied to prepare the effective adsorbent P-doped porous carbon (PC) of lanthanum ions (La3+). Doping of P was helpful to enhance the adsorption and selectivity of porous carbon to La3+. Compared with the samples without P-doping, the adsorption capacity of PC on La3+ was increased by >4 times, and the theoretical maximum adsorption capacity is as high as 342.2 mg g−1, which was greater than that of other reported carbon-based materials. In addition, the selective adsorption of PC on La3+ was as high as 96.07 % and 71.07 % not only in the multi-ion coexistence system of La3+, Ni2+, Zn2+, Co2+, Ca2+, and Na+, but also in the La3+/Na+ (1:50) coexistence system with very low La3+ content, respectively. The adsorption of La3+ on PC-800 is mainly chemisorption, where C-P-O, C/P=O and C-O-P groups are the main active sites for adsorption and improves the selectivity. This work can furnish some useful message on designing and synthesizing of carbon-based adsorbent, which has excellent adsorption selectivity in polyionic and low La3+ coexistence systems.