Sustainable Wastewater Treatment: Raw and Activated Cow Dung for the Sorption of Methylene Blue Dye

Abstract

Water pollution caused by synthetic dyes, like methylene blue, is a threat to the existence of biogenic components of the environment. This study explores the use of raw cow dung (RCD) and treated (acid treatment) cow dung (TCD) as effective sorbents to remove methylene blue (MB) from wastewater. The optimal conditions for MB removal of 58.3% (RCD) and 86.6% (TCD) were determined as 300 mg/L initial dye concentration, 120 min for RCD, and 100 min for TCD contact time, 50 °C temperature, and pH 5.0. Maximum adsorption capacity of 47.8 mg/g and 64.26 mg/g were determined for RCD and TCD, respectively. Thermodynamic parameter of enthalpy change (ΔH° = 9.32 kJ/mol for RCD and 6.40 kJ/mol for TCD) indicated an endothermic process. Fourier transform infrared spectroscopy (FT-IR) identified functional groups, such as OH, -NH₂, C=O, and C-O, as being responsible for the uptake of the dye molecules. The study confirms that activated cow dung is a sustainable, cost-effective alternative to conventional adsorbents like activated carbon for dye removal.