Fabrication of electrospun cellulose/ball-milled bone char membranes for fast, efficient and selective sorption of aquatic U(VI)

Abstract

Powdered sorbents in aqueous solutions suffer from the deficiency in the solid/liquid separation even the sorption capacities were higher than their bulk or less-dispersed forms. The combination of powdered sorbents with membranes would be highly desired to balance the contradiction between high separation efficiency and sorption capability. In this study, cellulose/ball-milled bone char (CL/MB) membranes with sub-micrometer diameter (276.0–281.7 nm) and developed porosity (21.5–98.6 m2/g) were fabricated by electrospinning technique. Bone chars originated from the pyrolysis of bone residuals at 350 °C, 500 °C and 650 °C could well dispersed in the electrospinning solvent. CL/MB membranes could adsorb U(VI) with fast kinetics (180.0 min), efficient capacity (309.8 mg/g at pH 5.00 and T 298 K) and excellent selectivity against the interference of coexisting ions in simulated waters. With spectroscopic analysis, the formation of (Ca(UO2)2(PO4)2(H2O)3 precipitation was dominant for the selectivity. The surface complexation of O-/reductive N-groups with U(VI), the electrostatic attraction of deprotonated O- with positively charged U(VI) species, the cation exchange of U(VI) with Ca2+ components, and the cation-π coordination of U(VI) should also be considered. This study pave the way for the feasible utilization of electrospun CL/MB membranes as a promising sorbent to capture aquatic U(VI).