The resources of clean water worldwide are very limited, and climate change is already affecting the available supplies. Therefore, developing a low-cost, highly efficient, and recyclable adsorbent to upgrade water quality has become an essential task. Herein, we report the fabrication of activated carbon (AC) adsorbents derived from lignocellulosic wastes. Both physical and chemical activation were investigated to modify the surface texture properties. The results indicated that increasing the activation temperature, whether physically or chemically, increases the specific surface area (S_BET). On the contrary, increasing the amount of the chemical activating agent significantly decreases the S_BET values. The S_BET of 1771, 2120, and 2490 m² g⁻¹ were obtained for water vapor, K₂CO₃ and KOH, at activation temperatures of 950 °C, 800 °C, and 800 °C, respectively. Methylene blue (MB) and phenol were used as adsorbates for the adsorption experiment. Adsorption of methylene blue dye revealed the ability of the water activated carbon to remove more than 95% of the dye (100 ppm) within 5 min with an adsorption capacity of 148.8 mg g⁻¹. For phenol adsorption, Several parameters were investigated, including initial concentration (50–250 ppm), pH (2–10), contact time (5–60 min), and temperature (25–45 °C). The highest adsorption capacity of phenol achieved was 158.9 mg g⁻¹. The kinetics of adsorption of phenol was better described by pseudo-second-order reaction while the isotherm process using Langmuir model. This study presents a roadmap for conversion of lignocellulosic biomass waste into highly efficient porous carbon adsorbents.