Utilization of Hydrochloric Acid-Modified Soybean Hull in the Removal of Chloroquine from Aqueous Solutions

Population growth, industrialization, and agricultural expansion intensify environmental pollution and challenge conventional water treatment systems, essential for public health. Given the inefficiency of these systems in removing emerging pollutants (EPs), such as chloroquine (CQN), this study aimed to investigate the modification on soybean hull residue by an minimal chemical interference, using acid-activated applied in the removal of CQN from aqueous solutions through batch experiments. The material was characterized by Zeta potential, FTIR, XRD, nitrogen physisorption (BET), TGA, SEM, and TEM, confirming its porous and functional nature. Adsorption assays evaluated the effect of pH, adsorbent mass, and temperature, fitting the data to kinetic and equilibrium models. The results showed that adsorption kinetics followed the pseudo-first-order (PFO) model, while the isotherms fitted best to the Sips model. The maximum adsorption capacity was obtained with 0.01 g of the soybean hull acid-activated (ASH), pH 7.0, and 308 K, achieving 77% CQN removal, maintaining approximately 50% efficiency after five reuse cycles. Furthermore, the environmental impact of adsorbent production was quantified using Green Chemistry metrics. In this sense, regarding adsorbent synthesis, its showed a low Mass Intensity (1,13 Kg Kg⁻¹) on the process, as well as a high Reaction Mass Efficiency (88,39%) and an E Factor (EF) remarkably low of 0,13, indicating a minimal residue generation and elevated yield from agroindustry residues. Despite Water Intensity presented a index of 213,89 Kg Kg⁻¹ related to washing the biomass, the process was based on diluted hydrochloric acid (0,1 mol L⁻¹), meaning a slight chemical activation strategy by using low reagent demand. Thus, the combination of CQN removal and a sustainable production route depicted by low chemical demand and adherence to circular economy principles demonstrates that modified soybean hulls are a viable and eco-friendly alternative for treating contaminated water by pharmaceuticals.