Fixed-bed adsorption of methylene blue solution onto sorghum grain husks

Abstract

This work contributes to the development and valorisation of natural adsorbents for use in industrial wastewater treatment processes. Sorghum grain husks, collected as agricultural waste from southern Algeria, were tested as an adsorbent to remove methylene blue from water using a fixed-bed column. Fourier transform infrared spectroscopy, point of zero charge, and scanning electron microscopy were used to assess the raw sorghum husk. The breakthrough curves were obtained at various values of the following parameters: bed height, flow rate, initial methylene blue concentration, and Hydrogen potential of solution. At an alkaline medium, the best methylene blue adsorption performance was observed. In a fixed-bed adsorption column, the highest uptake of methylene blue was 39.86 mg/g. Hydrochloric acid (0.1N) was used in regeneration tests for the fixed bed to enable multiple reuses of the natural adsorbent material. Both the Thomas and Yoon-Nelson models were used to find kinetic parameters.