Adsorption-desorption of methylene blue in a fixed-bed reactor filled with cotton industry waste

Abstract

The agricultural economy of Chaco province, in Argentina, is based on cotton production, which generates a significant environmental impact due to the solid waste it produces. The textile industry, which utilizes large amounts of dye, chemicals, and water in its manufacturing process, exacerbates this impact. While adsorption is recognized as the most efficient method for color removal, the commonly used adsorbent, activated carbon, is costly. Therefore, there is a search for low-cost alternatives. In this study, a laboratory-scale fixed-bed reactor filled with cotton husk as the adsorbent material was employed to conduct breakthrough curves and assess the adsorption-desorption process of methylene blue. The experiments were conducted at 25°C with a flow rate of 80 ml/hr. The desorption capacity of three substances, namely NaCl 0.1 M, ethyl alcohol 50% V/V, and tap water, was evaluated. Remarkably, three adsorption-desorption cycles were achieved in all cases.These findings suggest that cotton husk could serve as a viable low-cost material for dye adsorption. Moreover, the fixed-bed column proved to be an effective reactor type for studying the adsorption-desorption process.