Ultrasound-assisted and hydroalcoholic-freezing combination modification for the preparation of biomass sorbent from waste peach wood branches to efficient removal of methylene blue

Although there are many published techniques for green preparation of biosorbents, the adsorption results have not been satisfactory. In view of this state of affairs, this study developed a high-performance biosorbent based on waste peach wood branches (PWBs) to remove methylene blue (MB) from wastewater by ultrasound-assisted and hydroalcoholic-freezing combination modification (UHF) of green preparation technology. The results demonstrated that UHF as a green preparation technology effectively increased the maximum equilibrium adsorption capacity of PWB to 343.72 mg/g at the optimal conditions of 100 mg of adsorbent dose, 100 mg/L initial concentration of solution, room temperature, and unadjusted pH (5.6), and allowing rapid adsorption within 10 min. The entire adsorption process applied to the Langmuir and Freundlich isotherm models and the adsorption behavior of PWB were appropriately described by the pseudo-second-order kinetics. Adsorption was both spontaneous and exothermic. Various characterization methods such as SEM, FT-IR, XRD, BET, and Zeta potential illustrated that the adsorption mechanism of PWB to MB included ion exchange, electrostatic action, H-bond, pi-pi interaction, and ion-dipole interaction. In summary, these findings may provide a new idea for the development of green preparation method of biosorbents and the environmentally friendly treatment of agroforestry waste.