Visible light responsive photoactive polymer supported on carbonaceous biomass for photocatalytic water remediation

Polymers have emerged as a new group of photoactive materials owing to their excellent optical and electronic properties. In this work, we report the synthesis and application of novel conjugated polymer for photocatalytic water remediation. The photoactive polymer was fabricated via the heat polymerization of Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) into the Polyvinylpyrrolidone (PVP) host polymer (with mass ratio of 98%). TCTA is an electron rich with high lying LUMO and band gap of Eg = 3.4 eV, however, its polymerization with PVP results in higher visible light response until 900 nm. Two conjugated polymer samples were prepared with low and high TCTA contains, namely CP1 and CP2, respectively. The as-prepared photoactive samples were used as photoredox catalysts for the photocatalytic reduction of Cr(VI) and oxidation of MB under visible light (420 nm). CP2 showed higher visible light response, better electrochemical activity and excellent photocatalytic activity compared to CP1. In terms of Cr(VI) photoreduction, CP2 (0.25 g/L) can totally reduce Cr(VI) (20 ppm) at pH ranging from 3 to 8 under visible light. A total reduction of 40 ppm of Cr(VI) was found within 60 min using 0.75 g/L of CP2. 98% of MB was oxidized within 90 min using 0.25 g/L of CP2 under visible light. The photoactive polymer was supported into lignocellulosic biomass for higher surface area and better stability. As a result, this latter composite showed an enhanced adsorption capacity and photocatalytic efficiency towards Cr(VI) and MB compared to bare photoactive polymer. The main compounds used to fabricate this composite including PVP and natural biomass are eco-friendly, safe and low-cost which make it economically feasible photocatalyst for water remediation or other photoredox systems.