Purification of Pesticide-Contaminated Water Using Activated Carbon from Prickly Pear Seeds for Environmentally Friendly Reuse in a Circular Economy

This study proposes an innovative approach based on the concept of the circular economy. It involves treating deltamethrin-contaminated water using an activated carbon (AC) adsorption technique based on a highly adsorbent plant waste derived from prickly pear seeds (PPSs). Activated carbon was prepared from PPS via a simple pyrolysis process preceded by chemical impregnation with phosphoric acid. Thus, a whole range of physicochemical tests were carried out, including iodine number ( Q I 2 ), methylene blue number (Q MB ), Bohem dosage, pH ZC , Brunauer–Emmett–Teller analysis (BET), and scanning electron microscopy (SEM). The Q I 2 and Q MB were, respectively, 963.5 (mg g −1 ) and 8.3 (mg g −1 ). The pH zc of activated carbon was 2.5, and the surface area BET was 1161.3 m 2 g −1 . Adsorption kinetics, isotherms, and thermodynamic studies of pesticides using activated carbon were established. The obtained results revealed that the adsorption of the pesticide by the activated carbon appeared to be chemisorption with an adsorption capacity of 1.13 mg g −1 . The adsorption capacity increased with increasing temperature, which explains an endothermic adsorption interaction. These results are in agreement with the results found using the density functional theory (DFT) and showed that activated carbon has an interesting adsorption power, which makes it as efficient as commercial activated carbon and predisposes it to the depollution of aqueous solutions contaminated with pesticides.