Watermelon peels biochar-S for adsorption of Cu2+ from water
Mohamed A. El-Nemr, Murat Yılmaz, Safaa Ragab, Ahmed El Nemr
Abstract
ABSTRACT In this study, new biochar was produced from watermelon peel residues by dehydration process. The ability of the newly generated biochar-S to remove Cu 2+ ions from aqueous solutions was examined. Watermelon peel was used to make biochar-S, which was made by dehydrating by boiling with 50% sulfuric acid. Scanning electron microscopy, Brunauer–Emmett–Teller, Fourier-transform infrared spectroscopy, Barrett–Joyner–Halenda, differential scanning calorimetry, thermal gravimetric analysis and energy-dispersive X-ray analysis studies were used to characterize the biochar-S. The ideal pH for Cu 2+ ion adsorption was found to be 5.6. 1.0 g L –1 of biochar-S as an adsorbents dosage with Cu 2+ ions beginning concentration of 200 mg L –1 had the maximum Cu 2+ ions removal percentage of 78.33%. The maximal adsorption capacity ( Q m ) of bio-char-S was 151.52 mg g –1 . Isotherm models such as Dubinin–Radushkevich, Langmuir, Temkin, and Freundlich were used to analyze the experimental data. Furthermore, the data of these isotherm models were investigated using several error function equations (average percentage errors, hybrid error function, Chi-square error (χ 2 ), sum of absolute errors, root mean square errors, and Marquardt’s percentage standard deviation). The biochar-S experimental data was best suited by the Freundlich isotherm model. Pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models were used to assess the kinetic data. The adsorption rate was predominantly influenced by a pseudo-second-order rate model that had a high correlation ( R 2 > 0.99). The primary mechanism of Cu 2+ ion adsorption by biochar-S consists mostly of surface precipitation by the formation of insoluble copper compounds in an alkaline state and ion exchange with exchangeable cations in biochar such as aluminium, silicon, and calcium ions for copper ions. The findings suggest that biochar-S is a promising adsorbent for the adsorption of Cu 2+ ions and that it can be employed repeatedly without losing adsorption efficiency.