Adsorption and photocatalytic degradation of cationic dyes over bismuth ferrite (BFO) intercalated on liquid natural rubber-based hydrogel compound

Abstract

A hydrogel-based photocatalyst was employed to remove methylene blue (MB) and safranin dye effluents from wastewater using a liquid natural rubber (LNR)-acrylic acid (AAc) based bismuth ferrite (BFO) hydrogel compound. Response Surface Methodology (RSM) was used in this research to optimize several parameters for the synthesis of hydrogel compound and adsorptive-photodegradation process. Without a post-treatment separation phase, safranin and MB dye were able to maintain dye removal for up to six and five cycles with 99% dye removal, respectively, explaining the hydrogel’s stability and adsorptive efficiency. Furthermore, MB and safranin dyes were adsorbed and photodegraded very rapidly under a xenon lamp compared to the dye removal efficacy at dark, proving BFO has aided in the photodegradation process adsorbs further the dye effluents in which the hydroxyl radical (·OH) and superoxide radical (·O2–) species were responsible for the photocatalytic activity. It has been proposed that safranin and MB dye effluent adsorption matches the pseudo-second-order kinetic model and Freundlich isotherm model. A positive entropy number, S, in thermodynamic analysis indicates that the reaction has become more random, boosting the system's spontaneity. Meanwhile, it is found that adsorption rate of safranin is highly dependent on pH and is under the influence of inner sphere surface complexes. Thus, the synthesized LNR-g-MaH/AAc-BFO hydrogel compound in this study has shown excellent performance in the removal of dye effluents for the wastewater treatment process with enhanced stability.