Next-generation materials for phenol abatement: hydrogel and nanotech perspectives

Phenol and its derivatives, commonly detected not only in industrial effluents but also in various wastewater treatment systems, pose significant environmental and health hazards due to their toxicity to humans and aquatic life. This review focuses on the recent advancements in hydrogel-based nanocomposites for sustainable phenol remediation. Various types of hydrogels, nanoparticles, and their integrated hydrogel–nanoparticle composites are discussed in terms of synthesis techniques and structural properties. This study also examines different degradation mechanisms, including adsorption, photocatalysis, and advanced oxidation processes, highlighting their effectiveness in phenol removal. Key influencing factors such as initial pH, catalyst type, and reactant concentrations are critically analysed for their roles in enhancing degradation efficiency. In addition, comprehensive characterisation techniques like high-resolution transmission electron microscopy, X-ray diffraction, and field emission scanning electron microscopy are reviewed to evaluate the morphology and crystallinity of nanoparticles. Reported degradation efficiencies of phenol using various nanomaterials are summarised to establish comparative insights. This review aims to provide a consolidated understanding of nanocomposite hydrogel-based systems for effective phenol degradation, contributing to the development of sustainable wastewater treatment technologies.