Recent advances in the development of effective TiO2-based photocatalysts immobilized on floating substrates: A mini review

Among semiconductor-based photocatalysts, titanium dioxide (TiO₂) is one of the promising materials due to its excellent photocatalytic activity, natural abundance, non-toxicity, cost-effectiveness, biocompatibility, and high stability across a wide range of pH levels. However, current TiO₂-based photocatalysts are primarily available in powder form, which presents bottlenecks such as agglomeration of particles leading to inefficient photodegradation and issues in filtration and separation after wastewater treatment that can potentially cause secondary pollution. To address these challenges, the development of immobilizing TiO₂ on floating substrates offers a viable solution. This review article assesses the advantages of immobilizing TiO₂-based photocatalysts on floating substrates, such as bentonite, polyurethane, hydrogels, and cork, to improve photocatalytic efficiency and reusability compared to conventional TiO₂ powder. The utilization of different lightweight materials and various immobilizing techniques used for immobilizing TiO₂ particles have been discussed, highlighting their impact on addressing the limitations of powder based TiO₂ photocatalysts and enhancing photocatalytic performance. However, limitations associated with different substrate materials and immobilization techniques, such as substrate degradation, the need for additional chemicals, and photocatalyst leaching due to improper immobilization techniques, are also discussed in this review article. Furthermore, this review article also outlines future directions for developing effective TiO₂-based photocatalysts for wastewater treatment applications.