Bio-Inspired Hydroxyapatite-Chitosan Composite for Enhanced Indigo Blue Dye Removal: Kinetic and Adsorption Optimization Study

Abstract

The presence of dye molecules in water has a number of negative effects on aquatic and terrestrial animals. This study aimed to synthesize and characterize a composite of hydroxyapatite and chitosan to adsorb Indigo Blue (IB) dye from water, and to optimize its use for the adsorption process using the Response Surface Methodology (RSM) modelling tool. The combination of hydroxyapatite obtained from goat bone and chitosan obtained from periwinkle shell was carried out to enhance the mechanical strength and removal efficiency of the adsorbent. The formulated adsorbent was characterized using BET surface area, SEM-EDX, FTIR, XRD, and XRF techniques. Response surface methodology (RSM) using Box-Behnken Design (BBD) was employed to develop a series of batch-wise adsorption experiments. Findings revealed the R² value of the RSM optimization tool to be 0.9854. The optimized conditions used for the adsorption experiments were 180 min, 8.6, 150 mg/L, and 1 g for the adsorption time, pH, dye concentration, and adsorbent dosage, respectively, resulting in an adsorption efficiency of 80.92 %.