Removal of methylene blue from aqueous solutions with biochar prepared from pumpkin peel with sulfuric acid (H₂SO₄)

This study aims to investigate the adsorption behavior of methylene blue (MB) cationic dye on biochar prepared with sulfuric acid from pumpkin (PB). It was aimed to create a low cost adsorbent from agricultural waste, and biochar with a multilayer surface area of 3.92 m² g-1 was obtained. For adsorbent characterization, FTIR analysis was performed with partial and elemental analyzes in addition to the surface area, and SEM images were taken. In order to characterize the adsorption of MB dye with PB, the effects of solution pH, contact time, initial MB concentration and adsorbent dose changes were examined and 1440 minutes contact time was found suitable at the original solution pH. Equilibrium modeling results showed that the Langmuir isotherm is the most compatible model for MB adsorption with PB, based on the highest coefficient r2, indicating that monolayer adsorption is dominant. With the Langmuir isotherm, the maximum adsorption capacity was calculated as 208.33 mg g-1. Kinetic modeling results showed that the kinetic behavior of the adsorption mechanism of MB dye on PB can be explained better with the pseudo second order kinetic model. The results obtained show that it is possible to evaluate PB as an effective adsorbent for MB removal.