Preparation of graphene oxide from Bio-soot wastes: As an efficient adsorbent for highly noxious Congo red dye

Abstract

In this study, the morphological structure of Bio-soot obtained from diesel engine was first investigated. It is observed that Bio-soot has a higher level of graphitization than Carbon Black or activated charcoal. Graphene oxide was prepared by oxidizing the Bio-soot powder using modified Hummer’s method. The prepared graphene oxide was characterized by using X-ray diffractometer (XRD), Fourier transformation infrared (FTIR), Raman, Brunauer-Emmett-Teller (BET), Field emission scanning electron microscopy (FESEM) and High resolution transmission electron microscopy (HRTEM) analytical techniques. The prepared graphene oxide was used as adsorbent for decontamination of highly toxic Congo red from aqueous media. The adsorption studies were carried out using UV–visible Spectroscopy while changing the different parameters such as adsorbent dosages, pH of the solution, contact time and initial concentration. The obtained adsorption results were fitted with kinetic and isotherm models and was concluded that adsorption of Congo red follows second order kinetic and Langmuir isotherm models with maximum adsorption capacities of 120.20 mg/g. This reflects the significance of graphene oxide over Bio-soot which owes due to increase of the adsorption sites after introducing oxygen containing groups on Bio-soot surface. Thermodynamic studies revealed that Congo red adsorption on graphene oxide surface is spontaneous and endothermic in nature.