Removal of Methylene Blue from an Aqueous Medium Using Atemoya Peel as a Low-cost Adsorbent

This study prepared a biosorbent from the agricultural waste of atemoya peels, which was then used to remove the methylene blue dye. The atemoya peels were used in natura , and some were subjected to an alkaline treatment. The pH values obtained for the points of zero charge were 6.0 and 8.0 for the untreated and alkaline-treated materials, respectively. For neutral and/or alkaline pH values, the untreated and treated materials achieved average removals of approximately 80% and 90%, respectively. A kinetic study of the model dye removal profile showed a higher removal ratio over a shorter period for the alkaline-treated material. This profile is described by the pseudo-second-order model, which was the best fit for the D-R isotherm in both biosorbents. The maximum biosorption capacities were 190.18 mg g −1 (untreated) and 264.50 mg g −1 (treated) at 45 °C, and the alkaline-treated materials were shown to be reusable for at least 5 cycles. The results show that these biosorbents are efficient and cost-effective to remove the studied model molecules.