Green Synthesis of GO-MgO Nanocomposite using papaya leaf extract and Its utilization in removing Cr(VI) ions from aqueous media

Green synthesis of nanoparticles is an emerging research topic in green nanotechnology because it is nontoxic, environmentally friendly, and less expensive than physical and chemical approaches for nanomaterial production. Graphene oxide has been proved to be a viable adsorbent material to remove heavy metals due to its large surface area and many oxygen-containing groups. Magnesium oxide nanoparticles are biocompatible and exhibit excellent stability under harsh conditions. In this study, GO decorated MgO nanomaterial (GO-MgO) was created utilising a plant-mediated synthetic method with Carica papaya leaf extract & characterization was done with XRD, FTIR, SEM, and EDX analytical techniques. To estimate the Cr(VI) adsorption by GO-MgO, effects of adsorbent dose, pH, contact time, initial concentration, and co-existing anions were investigated. It was compared with GO, MgO and chemically synthesized GO-MgO to determine the best sorbent. Reusability of the green synthesized GO-MgO was studied. Maximum adsorption efficiency occurred at pH = 4 and a contact time of 60 minutes. Maximum adsorption capacity for green synthesised GO-MgO was 178.57 mg/g which is more than another adsorbent. Adsorption process followed the Langmuir isotherm and pseudo-second-order kinetic models. The Cr adsorbed GO-MgO can reused successfully up to 5 consecutive cycles.