Green and Ecofriendly Biochar Preparation from Pumpkin Peel and Its Usage as an Adsorbent for Methylene Blue Removal from Aqueous Solutions

This study aims to investigate the adsorption of methylene blue (MB) cationic dye on biochar prepared with sulfuric acid from pumpkin peel as a low-cost adsorbent from agricultural waste. The structure of pumpkin peel biochar (PPB) was investigated by proximate analysis, SEM-EDS, BET surface area determination, CHNS elemental analysis, and FT-IR techniques. The C content of PPB was found to be 63.5%, and its BET surface area is 3.9 m(2)/g. To characterize the adsorption ability of PPB towards MB from aqueous solutions, the effects of pH, contact time, initial MB concentration, and PPB dosage were examined. The MB adsorption onto PPB was favored at pH values between 6.0 and 9.0, and reached to equilibrium conditions at 16 h of contact time. Increasing of initial MB concentration caused an increase in adsorbed amount of MB per gram of PPB until 207.5 mg/g. MB adsorption equilibrium conditions were analyzed, and Langmuir isotherm is the most compatible model for MB adsorption with PPB indicating that monolayer adsorption is dominant providing maximum adsorption capacity of 208.3 mg/g. Kinetic studies showed that adsorption of MB dye on PPB was explained better with the pseudo-second-order kinetic model. Eventually, it was concluded that the PPB is an effective adsorbent for MB removal from wastewater.

Automated summary

This study investigated the adsorption of methylene blue (MB) dye on biochar prepared from pumpkin peel as a low-cost adsorbent. Various techniques were used to analyze the structure of the biochar and it was found to be effective in removing MB from wastewater. Kinetic studies showed that the adsorption process followed a pseudo-second-order model on the biochar. Overall, the results suggest that pumpkin peel biochar is a promising low-cost adsorbent for MB removal.