Fabrication and evaluation of multilevel Janus-imprinted nanocomposite membranes through a connective method of dip-coating and delayed phase inversion for simultaneous adsorption and separation of tetrabromobisphenol A and cadmium ion

Janus imprinted membrane (JIM) fabricated through the connective method of phase inversion and dip-coating processes has gained considerable attention in the separation field. Herein, a JIM with specific artificial receptors was prepared for the selective adsorption and separation of tetrabromobisphenol A (TBBPA) and cadmium ion (Cd²⁺). Dip coating method performed on the smooth surface of plate glass was used for the growth of polyaniline (PANI) imprinted polymers with specific imprinted cavities for TBBPA. The casting solution was coated on the imprinted polymers, which was then immersed into the coagulating bath containing gallic acid (GA) to achieve a delayed phase inversion process. The adsorption results showed that the rebinding capacities of the JIM for TBBPA and Cd²⁺ were 58.279 mg g⁻¹ and 83.159 mg g⁻¹, respectively. Meanwhile, the JIM exhibited superior rebinding selectivity with selectivity coefficients of 2.56, 2.87, 3.07, 2.52, 3.53, 3.66 and 4.05 for Pb²⁺, Cu²⁺, Zn²⁺, Sn²⁺, Hg²⁺, Co²⁺ and Cr³⁺ and 2.44, 2.56, 2.67 for BP, BPA and BBPA, respectively. The synthesized JIM showed tiny changes in rebinding capacity after 10 times cycles, revealing desirable regeneration performance. Finally, the pollutants on membrane surface were severally collected to avert the secondary pollution. The current study demonstrated that connective method is a promising method for selective rebinding and sorting treatment of different pollutants.