Eco-safe chemicothermal conversion of industrial graphite waste to exfoliated graphene and evaluation as engineered adsorbent to remove toxic textile dyes

Abstract

Industrial graphite becomes waste after its use and dumping of such graphite waste leads to environmental damage and health risks, thus needs alternative measures. This study is the first of its kind to convert industrial graphite to exfoliated graphene(EG) and using EG as an adsorbent. The used conversion method is chemicothermal which is greener and competent. The resultant EG was micro-analyzed for its application as an engineered adsorbent. The adsorption capacity of EG is tested for the removal of five toxic dyes from aqueous solution, namely royal blue (RB), turquoise blue (TB), black supra (BS), navy blue (NB), and deep red (DR) for various environmental conditions. The order of adsorption at equilibrium was found to follow, DR > TB > BS > NB > RB at circum-neutral pH in the range of 5 - 25 mg/L of dye, having 0.2 gm of EG. The notable adsorption capacity of dye onto EG can be credited to the various interface mechanisms which were studied using kinetic and thermodynamic models. The reusability studies recommend EG as the alternate adsorbent against commercial activated carbon which holds a huge carbon and water footprint. These results suggest that the applicability of potential EG adsorbent can be extended to the removal of organic pollutants in water and wastewater treatment. The success of converting graphite waste to an engineered dye adsorbent couples the advantages of converting industrial waste to a beneficial product and removal of toxic dyes thus achieving the circular economy and sustainable development in industrial practices.