Adsorptive Removal of Methylene Blue and Methyl Orange Using Agricultural Waste–Derived Activated Carbon

The effectiveness of a low-cost Black plum activated carbon (BPAC) derived from agricultural waste in removing methylene blue (MB) and methyl orange (MO) dyes from laboratory-created wastewater was investigated. The adsorbent was characterized using Fourier infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM) and pH at point of zero charge (pHpzc). The batch adsorption method was employed to achieved the best performance of the adsorbent at various experimental parameters such as adsorbent dose (0.6 g), initial dye concentration (500 mg/L), contact time (60 min), pH of the solution (2 for MO and 12 for MB), particle size (75 µm) and temperature (303 K). The adsorption process followed the pseudo-second-order kinetic model with qcal = 9.09 mg/g and R2 = 0.9992 for MB and 0.87 mg/g and 0.9984 for MO. The values of experimental data also accord with Freundlich adsorption isotherm with highest correlation coefficient of 9927 for MB and 9910 for MO dye. The adsorbent exhibited heterogeneous surfaces, and the adsorption of MB and MO was thermodynamically feasible, endothermic and spontaneous process. Based on these findings, it can be concluded that the Black plum seed shell activated can be utilize in removing toxic cationic and anionic dyes from waste water.