Synthesis and Application of NaOH‐Activated Harmal‐Derived Biochar for Adsorptive Removal of p‐Nitrophenol from Aqueous Solution

Abstract

Increasing concerns about water pollution have highlighted the importance of developing new methods for wastewater treatment. From a green and sustainable point of view, biochar is classified as one of the most important candidates for wastewater treatment. This study used Harmal as a waste feedstock to prepare biochar, followed by the activation process using sodium hydroxide to improve its physical and chemical properties. Synthesized biochars were well characterized using various analytical techniques, such as BET, XRD, XPS, TGA, and SEM. The adsorption capacity of activated biochar with a high surface area (823 m 2 g −1 ) was evaluated by removing para‐nitrophenol from water. In this line, the effect of various factors was checked, such as the adsorbent weight, PNP concentrations, and pH of the solution, and the best result was obtained using 8 mg of activated biochar for 50 mL of a 10 ppm PNP solution.