Efficient removal of methylene blue by low-cost and biodegradable highly effective adsorbents based on biomass in the fixed bed column

Abstract

The adsorptive ability of sustainable biomass (spent coffee ground (SC) and water hyacinth (WH)) and activated biochar derived from WH to remove methylene blue (MB) from aqueous solution was evaluated under continuous fixed-bed column. Morphological structure and functional groups of WH and SC were determined by SEM and FTIR, respectively. The SEM showed the presence of porous structure of WH, whilst FTIR confirmed the presence of more hydroxyl groups at the WH surface, resulting in higher MB adsorption. A series of column experiments were performed with varying bed height and initial MB concentration. To determine the breakthrough curves and characteristic parameters for process design, Yoon-Nelson, Thomas and modified Dose-Response models were applied to experimental breakthrough data. The MB adsorption was dependent on the bed height and initial MB concentration. An increase in bed height resulted in improved adsorption capacity. With increasing initial MB concentration, the adsorption capacity decreased. The maximum adsorption capacity (Q0) of ∼391 mg/g by WH (at 0.75 cm bed height and 300 mg/L initial MB concentration) and ∼393 mg/g by its activated biochar (at 2 cm bed height and 200 mg/L initial MB concentration) was observed. The results showed that WH gave comparable MB adsorption capacity with a greater cost-effectiveness.