Abstract The uncontrolled discharge of synthetic dyes from industrial effluents poses severe environmental and health risks due to their toxicity, persistence, and resistance to biodegradation. Conventional treatment methods, such as coagulation, membrane filtration, and advanced oxidation, often fail to achieve complete removal or generate secondary waste, necessitating the development of sustainable alternatives. Bionanomaterials derived from biological sources and engineered at the nanoscale offer eco-friendly, cost-effective platforms for dye remediation through synergistic adsorption and photocatalysis. Their high surface area, tunable functional groups, and biocompatibility enable efficient capture and degradation of pollutants, while green synthesis routes enhance sustainability. This review systematically correlates synthesis pathways (hydrothermal, sol–gel, microwave-assisted, and bio-based), surface modification strategies, and characterization techniques (FTIR, SEM/TEM, XRD, BET, Raman) with performance metrics in dye removal. Reported adsorption capacities range from 120 ± 5 mg/g for methylene blue on cellulose composites to 450 ± 12 mg/g for Congo red on functionalized biochar. Photocatalytic degradation efficiencies typically reach 95 ± 3% under visible-light irradiation within 150 ± 20 min. Mechanistic insights reveal that adsorption involves electrostatic interactions, hydrogen bonding, and π–π stacking. On the other hand, photocatalysis relies on band-gap engineering and the generation of reactive oxygen species. Despite promising results, challenges remain in scalability, regeneration efficiency (typically retaining 85 ± 4% capacity after five cycles), and validation in real wastewater matrices. Overall, this review provides a consolidated framework to guide the sustainable design and practical implementation of bionanomaterials for advanced wastewater treatment. Future research should prioritize standardized synthesis protocols, hybrid systems, predictive modeling, and techno-economic feasibility assessments to accelerate the development of next-generation bionanomaterials for industrial-scale wastewater treatment.
Oyewo et al. (Mon,) studied this question.