Advances in nanomaterials for efficient petrochemical wastewater treatment: Synergistic removal of organic and inorganic pollutants

Petrochemical wastewater contains a complex mixture of recalcitrant organic pollutants (BTEX, PAHs, phenols) and inorganic contaminants (heavy metals, oxyanions, halides), demanding advanced treatment technologies that go beyond the limitations imposed by conventional physicochemical methods. Nanomaterials have emerged as transformative adsorbents given their high surface area, tunable functionality, and rapid contaminant uptake. This review presents a state-of-the-art synthesis of recent advances in nanostructured materials comprising metal oxides, carbon-based systems, biogenic nanomaterials, layered double hydroxides, MOFs, and nanocomposites for the selective and synergistic removal of organic and inorganic pollutants from petrochemical effluents. We critically evaluate the structure-property-performance relationships with an emphasis on how nanoscale morphology, surface charge, heteroatom doping, and hybridization dictate the adsorption mechanisms. Special attention is given to emerging trends, including multifunctional hierarchical architectures, plasmon-enhanced adsorption, green-synthesized nanomaterials, and hybrid catalytic-adsorptive systems capable of simultaneous pollutant abatement. Key bottlenecks such as nanoparticle recovery, long-term stability, secondary toxicity, and scale-up feasibility are examined to outline translational gaps between laboratory studies and industrial deployment. Finally, we propose future research pathways toward circular economy nanomaterials, AI-guided adsorbent design, and low-energy continuous-flow systems. This work connects fundamental insights with practical considerations necessary to establish a forward-looking roadmap for next-generation nano-adsorbents in petrochemical wastewater remediation.