Comparative study on safranin adsorption using modified macadamia nutshell biochar

Abstract The environmental impact of textile effluents is a significant concern due to their complex structure and low biodegradability, threatening aquatic ecosystems and public health. Safranin is a common dye used in the textile industry, is resistant to natural biodegradation; hence, requiring special treatment. Adsorption has emerged as a promising technique for eliminating this dye from industrial wastewater. As a result, this research investigates the adsorption of safranin dye from synthetic wastewater utilizing macadamia nutshell char (MNC). MNC was chemically activated using KOH at temperatures of 900 °C, and characterized using surface area analysis, ultimate analysis, X-XRF, and SEM techniques. To evaluate the safranin adsorption behavior, adsorption kinetics and isotherms were examined. Activating MNC with KOH solution (Activated-MNC) enhanced adsorption capacity (169.25 mg·g −1 ). The adsorption kinetics adhered to a Pseudo Second Order (PSO) model, while the adsorption equilibrium aligned with Freundlich isotherm. This study indicates that MNC, particularly when activated with KOH, offers a cost-effective solution for safranin removal in industrial wastewater treatment.