Evaluation of biochar produced from coffee husks as an alternative treatment for wastewater contaminated with agrochemicals in the southwestern region of Antioquia.

Luisa Piña , Carolina Cañaveral-Ángel, Marisol Restrepo-Franco, Camila Gomez , Santiago Erazo-Cabrera, Lida Arias Marín

Excessive use of herbicides, pesticides, and fertilizers has enhanced agricultural productivity but has also generated significant environmental impacts and public health risks. Chlorpyrifos, an organophosphorus insecticide, is highly persistent in the environment due to its affinity for organic matter and its ability to be transported via runoff into water bodies, where conventional wastewater treatments fail to remove it. In response to this challenge, biochar has emerged as a low-cost adsorbent with high potential, owing to its physicochemical properties derived from pyrolysis. In this study, the adsorption capacity of biochar derived from coffee husks—an abundant agricultural residue in Southwestern Antioquia—was evaluated for chlorpyrifos removal in water samples. The highest biochar yield (20%) was obtained by oven-drying the husks for three hours, producing a material with 9.50% moisture, 48.41% volatile matter, 15.85% ash, 26.24% fixed carbon, pH 10, and an electrical conductivity of 5.38 mS cm⁻¹. Scanning electron microscopy revealed a porous structure with diameters ranging from 3.31 to 42.60 µm. The biochar achieved removal efficiencies of up to 96.28%, exceeding 80% in six of the nine treatments evaluated. These findings demonstrate the strong potential of coffee husk-derived biochar as a sustainable and cost-effective adsorbent for agrochemical removal. Notably, treatments combining higher biochar doses with longer contact times achieved the best performance, underscoring the material’s applicability in real-world wastewater treatment systems.