A novel composite hydrogel for adsorption and photocatalytic degradation of bisphenol A by visible light irradiation

A novel hydrogel catalyst (P(HEA-co-HAM)-CdS) was synthesized to remove bisphenol A (BPA) from water through adsorption and in-situ photocatalytic degradation. The characterization of P(HEA-co-HAM)-CdS hydrogel through SEM-EDS, TEM, XPS and FT-IR demonstrated heterogeneous structure and chemical combination between CdS and hydrogel. Besides, the optical properties of P(HEA-co-HAM)-CdS hydrogel illustrated enhanced photocatalytic activity under visible light irradiation with efficient separation ability of electron-hole pairs and effective visible light utilization capability. In addition, the ability of hydrogel in adsorption and degradation were observed. BPA adsorption capacity of P(HEA-co-HAM)-CdS hydrogel was 11.26 mg/g, higher than similar adsorbents. The adsorption process fitted in pseudo-second-order rate equation and Langmuir monolayer adsorption. Under 500 W visible light irradiation, BPA degradation rate of P(HEA-co-HAM)-CdS hydrogel reached 92% in 3 h and photocatalytic oxidative radicals detection experiment verified holes (h+) and ·O2− play major role in this system, mineralization rate of BPA was 47%. HPLC-TOF-MS was employed to detect the degradation intermediates, with theoretically Fed2 value calculating results, possible degradation pathway of BPA was proposed. Furthermore, degradation rate remained over 84.4% after recycle. The results indicated that P(HEA-co-HAM)-CdS hydrogel was a promising catalyst material in application.