Enhanced lanthanum and cerium removal of self-powered electro-membrane bioreactor (SPEMBR) using high-active bi-functional M-N-CNTs@Fe/Mo electrode

Abstract

Lanthanum and cerium are widely used as important raw materials for energy storage batteries due to excellent natural electrical, magnetic, and optical properties. However, with the explosive growth of new energy generation and the environmental degradation-resistant of lanthanum and cerium, it is difficult to balance environmental sustainability and resource scarcity to achieve lanthanum-cerium removal by conventional chelate salt precipitation. Herein, a laboratory-scale self-powered electro-membrane bioreactor (SPEMBR), integrating high-active nitrogen-doped carbon nanotube-loaded iron and molybdenum bimetallic conductive composite electrode membrane (M−N−CNTs@Fe/Mo) by hydrothermal and phase inversion processes was successfully constructed and evaluated for removing lanthanum cerium from industrial wastewater. The prepared bi-functional M−N−CNTs@Fe/Mo5% electrode membrane exhibited a uniform morphology and excellent hydrophilicity, with nano pore lattice spacing only 0.2637 nm. Electrochemical test results demonstrated that the novel electrode indicated excellent redox properties (i0 = 8.35 × 10−3 A cm−2, Cdl = 1.13 mF cm−2) and efficient electron transfer efficiency (Rct = 4.69 Ω, n = 3.9). Based on optimized conditions (5)% doping ratio, pH = 10, C = 20 mg/L), the SPEMBR assisted by M−N−CNTs@Fe/Mo catalytic electrode membrane achieved approximately complete removal efficiency of lanthanum and cerium (>99.2 %), superior to most publicly available related studies (86.3 %-99.0 %), but with a calculation cost of only $8.54. Identification of membrane interface products and system precipitates demonstrated that the outstanding removal efficiency was attributed to the combined reaction mechanism of electroreduction, electrocoagulation and electromembrane filtration. This work provides a bright application prospect for low-cost and effective removal of lanthanum cerium metal based on electrode membranes.