LEMONGRASS HYDROCHAR SYNTHESIZED BY HYDROTHERMAL METHOD IN KOH ENVIRONMENT FOR METHYLENE BLUE AND Ni (II) ION ADSORPTION

Abstract

In this study, we focused on studying some characterizations, methylene blue (MB) and Nickel (II) ion (Ni(II)) adsorption of lemongrass hydrochar synthesized by hydrothermal method in base environment. Analysis the infrared spectroscopy (IR), scanning electron microscopy (SEM) and specific surface (BET) of synthesized materials shows that, the hydrothermal in base (H22KOH) is better than that on water (H22). The surface was more decomposed and had a larger specific surface area although some organic bonds and function groups were still retained. H22KOH adsorbs both MB and Ni (II) ions better than H22, the best pH for the adsorption of MB is 6 and Ni(II) ions is 7. As the H22KOH dose increase, the MB adsorption efficiency (AE) increases slowly while Ni(II) AE increases rapidly. H22KOH adsorbed MB faster than Ni(II) ions, the time to reach MB adsorption equilibrium in only 50 minutes while Ni(II) was 120 minutes. As the concentration of MB and Ni (II) ion increase, the AE increases, the highest MB adsorption capacity (q_{m, MB}) reached 32.43 mg/g and q_{m, Ni(II)} was 11.69 mg/g. The experimental adsorption process was consistent with Freundlich isotherm adsorption model and the first-order kinetic model. It means that, the adsorption mechanism is physical adsorption. In general, H22KOH is a prospective adsorbent to remove both inorganic and organic pollutants in water.