Removal of Phenolic Compounds Using Activated Carbon and Magnetized Activated Carbon from Cob Corn Waste

This research explores the production of activated carbon from a lignocellulosic precursor, corn cobs, as a potential method for the removal and adsorption of phenolic and nitrophenolic compounds. Colombia is a major corn producer, with a national production of 1,559,194 tons in 2024. Currently, approximately 0.5 to 3.2 kg of corn residue per kg of product is not commercially utilized. The objective is to focus on the removal of phenol, 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol from simulated solutions to evaluate the adsorption capacity under optimal conditions. Phenolic and nitrophenolic compounds are considered highly toxic molecules for the environment, especially in the plastics and agrochemical production sectors. These compounds are pollutants in wastewater due to their impact on aquatic life and human health. This not only contributes to the utilization of residual biomass but also to the circular economy by promoting its valorization in environmental remediation processes. The diameter and average volume of the pores are large enough to promote rapid diffusion kinetics of the phenolic compounds within the pore structure, which varies from 0.207 to 0.544 cm3 g−1, and their adsorption capacity. The most adsorbed phenol was found to be 4-nitrophenol, with up to 97 mg of contaminant (4-nitrophenol) adsorbed per gram of activated carbon (sample designated AC-TK), at initial concentrations ranging from 0.0 ppm to 3.0 ppm. Furthermore, magnetite plays a crucial role in the adsorption of 2-nitrophenol. With this compound, up to 86 mg of 2-nitrophenol per gram of activated carbon was adsorbed at a concentration of 14 ppm, whereas without magnetite, a smaller amount was adsorbed at lower initial concentrations (ppm) for the same compound.