The Adsorption of Pb(II) from Aqueous Solution Using KOH-Modified Banana Peel Hydrothermal Carbon: Adsorption Properties and Mechanistic Studies

Adopting banana peel as a raw material, the adsorption properties of banana peel hydrothermal carbon modified with a KOH solution for lead ions in aqueous solution were studied. The surface structure and functional groups of the modified hydrothermal carbon were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, the Brunner-Emmet-Teller (BET) method, element analysis, and Raman spectroscopy. The results showed that an adsorption capacity of 42.92 mg/g and a removal rate of 86.84% were achieved when the banana peel hydrothermal carbon was modified with a KOH solution of 0.5 mol/L, with a pH of 6 and a solid-liquid ratio of 1 g/L. The equilibrium adsorption time for lead ions in solution being adsorbed using KOH-modified hydrothermal carbon was 240 min, the adsorption process satisfied the quasi-second-order kinetic model and the Redlich-Peterson isotherm equation, and the equilibrium removal efficiency was 88.62%. The adsorption of lead ions using KOH-modified hydrothermal carbon is mainly chemical-physical adsorption.