Adsorption of 2,4-dichlorophenoxyacetic acid and 4-chlorophenol using bio-based activated carbon: Thermodynamics, kinetics and cytotoxicity evaluation

Abstract

This study investigates the use of peanut husk biowaste (PH) activated carbon to remove 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chlorophenol (4-CP) from water. Acid activation of PH enhances its structure, creating pores in the activated carbon. SEM, TEM, and XRD confirm the effectiveness of this process. BET analysis shows the increase in surface area from 0.775 to 547 ​m² ​g⁻¹ for the PH and PH-AC samples. PH-AC tested against 2,4-D and 4-CP, optimizing pH, contact time, pollutant dose, PH-AC dose, and temperature for maximum adsorption efficiencies. Maximum adsorption capacity for 2,4-D and 4-CP is 165.9 and 99.4 ​mg ​g⁻¹, respectively, higher than previous research. Kinetics, adsorption, and thermodynamic studies reveal the endothermic and spontaneous nature of the adsorption process. The adsorbent demonstrates stability and long-term applicability, with substantial adsorption capacities for four cycles. Cytotoxicity studies confirm non-toxicity and environmental friendliness of PH-AC material. These findings highlight the potential of PH-AC for wastewater treatment.