A ternary composite nanofibrous photocatalyst: FcLR-gC3N4/polyisothianaphthene/polyacrylonitrile for degradation of organic dyes

Abstract

BackgroundWater pollution by organic dyes is one of the important environmental issues. When substances such as organic dyes are discharged into water, they can severely pollute the water and harm the life of living organisms. MethodsA new ternary composite nanofibrous photocatalyst, FcLR-gC3N4/PITN/PAN, was produced through 1) synthesis of a graphitic carbon nitride (g-C3N4)-based ferrocenyl dithiophosphonic acid, FcLR-gC3N4, by the attachment of Ferrocenyl Lawesson's Reagent (FcLR) to g-C3N4 nanosheets, 2) incorporation of the FcLR-gC3N4 into the polymeric matrix of as-prepared polyisothianaphthene (PITN) blending with polyacrylonitrile (PAN), and 3) fabrication of electrospun nanofibers (NFs) through electrospinning. Significant findingsThe degradation of methyl orange (MO) and methylene blue (MB) was more efficient on FcLR-gC3N4 compared to g-C3N4 alone, and on FcLR-gC3N4/PITN/PAN compared to FcLR-gC3N4, confirming the effective role of both FcLR and PITN/PAN matrix in the degradation of the dyes. The ternary composite nanofiber degraded 92% of MB and 29% of MO. The MB mineralization percentages of 65% (TOC), 60% (COD), and 55% (BOD) were achieved after 2 h and 30 min. Radical trapping experiments consistent with the Tauc plots and Mott-Schottky plots distinguished O2•- as the primary species in the degradation mechanism of MB. The MB degradation pathway was determined through LC-MS-MS. The electrochemical impedance spectrum (EIS) and photocurrent measurements confirmed the higher photocatalytic activity of FcLR-gC3N4 compared to g-C3N4 alone by studying the charge carrier's separation and recombination. A high recyclability was found for FcLR-gC3N4. The recycling stability of FcLR-gC3N4 increased after its embedding into the nanofibrous matrix of PITN/PAN.