Adsorption dynamics of dye onto crab shell chitosan/neem leaf composite

Abstract

The aim of this study was to evaluate the adsorption dynamics of crab shell chitosan/neem leaf composite against methylene blue dye at varying concentrations (50 and 200 mg/L), bed depths (2.5 and 5.0 cm), and flow rates (2.17 and 2.90 mL/min). The chitosan composite has a specific surface of 258 m2 /g. Its surface is rich in amine/amide groups. The results reflect better dye adsorption at higher operating conditions. The maxi-mum dye adsorption capacity observed was almost 77 mg/g. The kinetics models showed good correlation with the experimental data and described the breakthrough behaviour of dye removal. The Thomas model predicts external and internal diffusion as the rate controlling mechanisms, while the Adams-Bohart model indicates a simultaneous steady state process of intraparticle diffusion and ionic interaction. Chitosan composite is a prom-ising adsorbent candidate for dye wastewater treatment.