Highly Efficient Purification of Multicomponent Wastewater by Electrospinning Kidney-Bean-Skin-like Porous H-PPAN/rGO-g-PAO@Ag+/Ag Composite Nanofibrous Membranes

Due to the complexity of harmful wastewater components, environmental and multifunctional materials are required for sewage purification. In this paper, a novel kidney-bean-skin-like hydrophilic porous polyacrylonitrile/reduced graphene oxide-g-poly(amidoxime)-loaded Ag+ (H-PPAN/rGO-g-PAO@Ag+/Ag) composite nanofiber membrane was fabricated by combining electrospinning and hydrolysis methods. The spinning solution was pumped at a rate of 0.4 mL/h with the voltage set at a constant value of 23 kV. Then, some of the -CN groups switched to hydrophilic -COOH groups via a hydrolysis method, which acts as a linker of GO-g-PAN, Ag+, and the polyacrylonitrile (PAN) matrix. A further step of chelation and thermal treatment were used for generating Schottky junctions between rGO-g-PAO@Ag+ and Ag. After five-cycle tests, it exhibited outstanding mechanical properties ensuring the filtration and purification performance of the H-PPAN/rGO-g-PAO@Ag+/Ag composite nanofiber membrane (i.e., the tensile strength was still 7.21 MPa, and the elongation was 61.53%) for simulated wastewater. The methods of thermal treatment and high-pressure Hg lamp irradiation promoted the reduction of GO to rGO and Ag+ to Ag particles, which endows the final product H-PPAN/rGO-g-PAO@Ag+/Ag with excellent photocatalytic and bactericidal properties. Its catalytic efficiency for dyes benzoic acid (BA), Rhodamine B (RhB), methylene blue (MB), and methyl orange (MO) was up to 99.8, 98, 95, and 91%. The antibacterial rate was 100% against Escherichia coli and 99% against Staphylococcus aureus. More importantly, the photocatalytic and antibacterial PAN-based nanofiber membrane can be simply scaled up, which provides the membrane with great potential in highly efficient wastewater treatment and augmenting water supply.