Removal of hydrocarbon pollutants from refinery wastewater using N-hexadecylchitosan as an efficient adsorptive platform

Abstract

The negative impact of refinery wastewater is of great concern to the aquatic, terrestrial, and aerial environment. In this study, N-hexadecylchitosan (NHDC) was successfully synthesized to deal with low mechanical strength, poor adsorption capacity, and limited selectivity of native chitosan. The NHDC was characterized by fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-Ray diffraction analysis (XRD) to study its composition, morphology, and structural attributes. The adsorption of hydrocarbon pollutants from refinery wastewater was studied in batch mode experiments. The results indicated that the removal of COD attained by chitosan and NHDC was 21 and 63%, respectively. COD removal was found to be maximal, i.e., 96% using 0.08 g of NHDC at 60 min in a solution of pH 6.5 maintained at 60 °C. Furthermore, kinetic data revealed that the adsorption system followed pseudo-second order kinetics, whereas equilibrium studies supported both monolayer and multilayer adsorption mechanisms. The designed adsorption platform was able to capture hydrocarbon pollutants under very mild optimized conditions. Furthermore, NHDC demonstrated long term stability when subjected to five successive cycles, which contributed to the sustainability of water treatment systems. On the basis of the outcome of this work, it is advocated that new biobased NHDC can be used as an efficient adsorbent for the remediation of organic contaminants laden wastewater streams generated from oil refineries.