Valorizing Moroccan crab shells to purify water from Orange G dye: Exploring equilibrium, kinetics, and thermodynamics

Abstract

A successful approach has been taken to develop a biomaterial derived from fish waste, using Moroccan fish processing by-products from crab shells. Moroccan crab ( Portunus pelagicus ) shell-derived biomaterial has been developed for wastewater treatment, using marine crustacean waste and addressing the challenges of solid fish waste management. The crab shell powder (CSP) was calcined at 800 °C for three hours and characterized using SEM, EDS, FTIR, and XRD, revealing a predominantly crystalline structure. The CSP's effectiveness as a biosorbent for the removal of the anionic dye Orange G (OG) was assessed under various conditions, including pH, biosorbent mass, temperature, and contact time. Optimal conditions achieved a 98.84 % dye removal rate within 60 min at an adsorbent dose of 0.09 g. The adsorption process adhered to the pseudo-second-order kinetic model and the Freundlich isotherm, indicating a spontaneous, endothermic surface reaction involving multilayer physisorption. The biosorption mechanism is thought to include electrostatic attractions, n-π stacking interactions, hydrogen bonding, and Yoshida hydrogen bonds. The study suggests that CSP is an efficient, eco-friendly adsorbent for industrial wastewater treatment, offering a promising solution for the valorization of fish waste by-products. ● Optimal conditions for OG biosorption onto CSP: 50 mg/L concentration, 0.09 g, 3 h stirring at 25 °C, pH= 3. ● Spontaneous endothermic surface reaction involving multilayer physisorption. ● Adsorption mechanism: electrostatic attractions, n-π stacking, hydrogen bonding, and Yoshida hydrogen bond. ● CSP could serve as an efficient and eco-friendly adsorbent in industrial wastewater processing.