Adsorption properties and mechanism of Pb²⁺ in hydrothermal carbon solution of modified banana peel

Abstract

Using banana peel as raw material, the adsorption properties of hydrothermal carbon pre-10 pared from banana peel modified with different concentrations of phosphoric acid solution for lead 11 ions in aqueous solution were studied. The surface structure and functional groups of the modified 12 hydrothermal carbon were analyzed by XRD and SEM. The results show that the surface of the 13 modified banana peel hydrothermal carbon prepared at 240℃ and 2mol/L phosphoric acid solution 14 has large pores. The adsorption capacity is larger when pH value is 6.When the concentration of 15 phosphoric acid solution was 2mol/L, the solid-liquid ratio was 2g/L, the adsorption capacity was 16 40.64mg/g, and the removal rate was 82.74%.When the initial concentration of lead solution in-17 creased to 100mg/L, the adsorption capacity of modified hydrothermal carbon for lead ion increased 18 to 76.81mg/g, and the removal rate decreased to 76.81%.The equilibrium adsorption time of banana 19 peel phosphoric acid modified hydrothermal carbon for lead ions in solution is 300min. The adsorp-20 tion process satisfies the pseudo-second-order kinetic model and Langmuir isotherm equation. The 21 reaction temperature is 313K, and the equilibrium adsorption capacity can reach 101.19mg/g. The 22 adsorption of Pb ions in aqueous solution by phosphoric acid modified hydrothermal carbon is 23 dominated by single layer chemisorption. The artificial neural network has a fitting correlation of 24 0.99, and the adsorption process includes physical adsorption, electrostatic attraction, ion exchange, 25 and surface complexation.