Symbiotically Augmented removal of Congo red by polyaniline/cobalt sulfide/graphite composites

Abstract

The presence of Congo red dye (CR) in industrial sewage causes a serious threat to the environment. Therefore, it is imperative to develop high-performance, low-cost functional materials to mitigate such issues. During past decades, polyaniline and its composites have been recognized as an emerging candidate to remove hazardous organic effluents from water. The present work demonstrates the successful elimination of CR from water in presence of newly synthesized graphite/cobalt sulfide/PANI-based ternary composites. Several morphological or physicochemical characterization tools were adopted to confirm the formation of the ternary composite and subsequent synergistic interaction between individual elements of the composites. The experimental results delineate that a maximum of ∼95.55% CR removal (%) was achieved after 120 min. Fast removal (∼5–10 min) of CR dye is observed for APS/Ternary composite system. From the fitted experimental data utilizing 1st or 2nd order rate kinetic models, it was observed that the adsorption induced degradation of CR dye and the process was chemisorptions in nature. Further, an intra-molecular diffusion model was also introduced that signifies both boundary layer diffusion or intraparticle diffusion phenomenon was responsible for CR removal. Furthermore, the cytotoxicity profile of the composite treated Congo red aqueous solution was evaluated when exposed to L929 fibroblast cells after 24 h or 72 h of exposure and the result deciphers the non-toxic nature of composite treated CR water.