Chitosan cross-linked polyaniline grafted graphene oxide composite: a new adsorbent to remove phenol and cationic dye from aqueous solutions

Rapid industrialisation has led to severe environmental pollution, mainly due to the discharge of organic pollutants into the waterbodies. The removal of organic compounds such as dyes and phenolic pollutants from the industrial effluents before it is discharged should be the top priority. This article synthesised a novel chitosan cross-linked polyaniline grafted graphene oxide (CS-PANI@GO) composite with variable morphology, enhanced surface area, low cost, biocompatibility, and notable characteristics of high malachite green (MG) and phenol adsorption capacity. The physicochemical properties of CS-PANI@GO were studied by FESEM, FTIR, XRD, RAMAN, BET, and BJH pore size distribution. FESEM analysis demonstrated that the surface of CS-PANI@GO composite is porous in nature. The BET surface area of the composite is 88.91 m2/g. The effect of various parameters such as temperature, pH of the solution, initial concentration of MG and phenol, adsorption time, and dosage were investigated, and the optimal values were recorded. The adsorption performance of CS-PANI@GO composite for both MG and phenol follows the pseudo-second-order model suggests chemisorption occurs in the process. For MG dye, the adsorption equilibrium data follows the Freundlich model and for phenol, the data follows the Langmuir model. The maximum uptake for MG dye and phenol were 699.022 mg/g and 198.254 mg/g, respectively. Thermodynamic data demonstrated that the process of MG and phenol adsorption was spontaneous, endothermic, and feasible. The recyclability study shows that after five cycles of regeneration, the composite has excellent adsorption performance. The adsorption mechanism is also proposed to be hydrogen bond, π-π interaction, and electrostatic attraction. Based on the present adsorption results under various parameter conditions, the synthesised novel CS-PANI@GO composite could be applied as an efficient adsorbent for the treatment of dyes and phenolic pollutants from wastewater.