Eco-Friendly Adsorption of Cationic (Methylene Blue) and Anionic (Congo Red) Dyes from Aqueous Solutions Using Sawdust

Abstract

In this study, sawdust (SWS) was employed as an eco-friendly and low-cost adsorbent for the removal of anionic (Congo red, CR) and cationic (methylene blue, MB) dyes from aqueous solutions at 25◦ C. The investigation encompasses various parameters affecting the adsorption process, including weight of sawdust adsorbent, pH, initial dye concentration, and equilibrium time. Characterization techniques such as Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were conducted for an in-depth understanding of the adsorption mechanism. Optimal conditions were found to be SWS weight of 0.1 g/L, dye concentration of 15 mg/L, and equilibrium time of 1 h. Under these conditions, removal percentages of 95.88% for MB and 67.78% for CR were achieved, with adsorption capacities of 14.35 mg/g and 10.22 mg/g, respectively. The results demonstrate that SWS, though considered waste, has significant potential as a low-cost adsorbent for dye removal from aqueous solutions. Removal efficiency increased with SWS weight, ranging from 75.54% to 98.50% for MB, and 50.86% to 80.012% for CR, while adsorption capacity (Qe) inversely correlated with surface weight, ranging from 45.55 to 9.12 mg/g for MB, and 15.23 to 8.076 mg/g for CR.