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Wastewater discharge from textile industries contribute much to water pollution and threaten the aqua ecosystem balance. Synthesis of agriculture waste based adsorbent is a smart move toward overcoming the critical environmental issues as well as a good waste management process implied. This research work describes the adsorption of methylene blue dye from aqueous solution on nickel oxide attached magnetic biochar derived from mangosteen peel. A series of characterization methods was employed such as FTIR, FESEM analysis and BET surface area analyzer to understand the adsorbent behavior produced at a heating temperature of 800${}^{\circ }$C for 20min duration. The adsorbate pH value was varied to investigate the adsorption kinetic trend and the isotherm models were developed by determining the equilibrium adsorption capacity at varied adsorbate initial concentration. Equilibrium adsorption isotherm models were measured for single component system and the calculated data were analyzed by using Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich isotherm equations. The Langmuir, Freundlich and Tempkin isotherm model exhibit a promising R²-correlation value of more than 0.95 for all three isotherm models. The Langmuir isotherm model reflectsan equilibrium adsorption capacity of 22.883mg$\cdot$g${}^{-1}$.

MIL-101(Cr)/AC was synthesized by in situ incorporation of activated carbon powder via hydrothermal method. The water stability, n-hexane adsorption and regeneration of the MIL-101(Cr)/AC were experimentally measured. The results showed that the MIL-101(Cr)/AC exhibited the larger surface area (3319.3m²/g) than that of MIL-101(Cr) and AC, respectively. The addition of activated carbon was beneficial to improve the yield of MIL-101(Cr)/AC. The pore structure parameter and XRD of the MIL-101(Cr)/AC changed little after in water for 24h. Furthermore, the adsorption capacity of MIL-101(Cr)/AC for n-hexane was 786mg/g, which increased to 23.0% and 27.7% compared with MIL-101(Cr) and AC, respectively. Kinetic fitting of data indicated that the pseudo-first order model can more accurately describe the adsorption process of n-hexane on MIL-101(Cr)/AC and the intraparticle diffusion was not the sole rate-controlling step. Besides, the regeneration efficiency of MIL-101(Cr)/AC was over 92% after 10 consecutive n-hexane adsorption/desorption cycles.

The adsorption behavior of acetic acid on zeolite 13X was studied at 25°C, 35°C and 45°C in a batch experiment. Experimental data were applied to pseudo-first-order and pseudo-second-order adsorption kinetic models, and tested against Langmuir and Freundlich isotherms. Thermodynamic parameters (ΔG, ΔH and ΔS) of adsorption were also calculated. The data fit the pseudo-second-order kinetic model and Freundlich isotherm well. The calculated values of ΔG, ΔH and ΔS indicate that the adsorption is spontaneous and endothermic; it causes an increased extent of randomness at the solid-solution interface.