The presence of pharmaceutical residues, such as ibuprofen, in aquatic environments poses a growing environmental challenge due to their persistence and potential ecotoxicological effects. In this study, a novel biohybrid composite based on pyrolysed rice husk (biochar) modified with Bacillus cereus cells was developed for the efficient removal of ibuprofen from aqueous solutions. The material was comprehensively characterised using SEM, BET, TGA, CHN analysis, and FTIR spectroscopy. Pyrolysis significantly increased the surface area (up to 300 m2 g−1) and porosity compared to raw rice husk, while bacterial immobilisation introduced additional functional groups, enhancing surface heterogeneity. Batch adsorption experiments demonstrated a clear improvement in adsorption capacity in the order of rice husk < biochar < composite. The maximum Langmuir adsorption capacities were 4.86, 11.68, and 13.73 mg g−1 for rice husk, biochar, and the composite, respectively. Isotherm modelling indicated that ibuprofen adsorption was best described by the Langmuir and the Freundlich models, suggesting a combination of monolayer adsorption and heterogeneous surface interactions. Isotherm analyses (D–R energy values < 9 kJ mol−1) indicate that ibuprofen removal occurs predominantly through physisorption, governed by π–π interactions, hydrogen bonding, and surface heterogeneity rather than chemisorption. Kinetic studies revealed rapid adsorption behaviour, with pseudo-first-order and pseudo-second-order models providing the best fit (R2 up to 0.997). The Weber–Morris model confirmed that intraparticle diffusion contributed to the process but was not the sole rate-limiting step. The enhanced performance of the composite is attributed to synergistic effects between physicochemical adsorption on the porous carbon matrix and interactions with bacterial cell wall functional groups. The developed composite represents a low-cost, sustainable, and highly effective material for ibuprofen removal from contaminated water.
Chwastowski et al. (2026) studied this question.