Surface-functionalized pomelo peel-derived biochar with mercapto-1,2,4-triazloe for selective elimination of toxic Pb (II) in aqueous solutions

A novel biochar adsorbent (GP-AMT) is prepared by functionalizing biochar derived from pomelo peel to eliminate Pb (II) from water. GP-AMT was characterized by FTIR, SEM, BET, TGA and XPS. GP-AMT has a large specific area and is multiaperture. The adsorption performance was studied. At the pH = 5, the maximum uptake amount of Pb(II) on GP-AMT reached 420 mg/g. The sorption behavior of GP-AMT obeys with Langmuir and pseudo second-order formula, which shows that the adsorbing property of GP-AMT is uniform chemical sorption. Thermodynamic studies attested that the sorption was an irreversible endothermic course. GP-AMT demonstrated excellent selectivity and reproducibility. After 5 cycles, it still has an excellent sorption property. XPS and zeta potential analysis revealed that the adsorbing nature of GP-AMT for heavy metal ions was coordination and ion exchange. In conclusion, surface modification of biochar can significantly improve its sorption capacity, selectivity and regenerative ability for Pb(II), and reduce the pomelo peel waste pollution.