Photocatalytic polymeric composites for wastewater treatment

Abstract Industrial discharges, agricultural practices, and other anthropogenic activities undoubtedly play an important role in the issue of aquatic pollution. These practices have a direct impact on abnormally increasing pollutant levels, alterations in the natural water cycle, and eventually on human health. Wastewater treatment by various methods like desalination, adsorption, and advanced oxidation processes supports the feasibility of sustainable and facile production of clean water. Heterogeneous photocatalysis derived from solar energy is a more effective, nontoxic, and eco-friendly technique than other, costlier methods generally employed. However, some limitations have been noticed regarding the relatively slower performance of photocatalysts. Some major drawbacks are wide bandgap, high energy consumption, and low quantum efficiency. Various strategies have been formulated for the solution of these problems via the development of advanced photocatalysts. To enhance the photocatalytic efficiency, a feasible approach is to incorporate/dope metals, nonmetals, and semiconductor heterojunctions. Polymer-based photocatalysts are reported as more efficient due to high surface area, porous nature and, above all, being synthesized through environmentally friendly methods. Conducting polymers have taken a leading place recently due to their conjugated structures and attractive features. This innovative combination provides synergistic effects of modified photocatalysts, semiconductor heterojunctions, and polymers, showing higher and faster pollutant removal percentages than pure components due to adsorption enhanced photocatalysis. Moreover, the composite's high recovery, easy separation, durability, and efficient reusability make it superior to others. In this chapter we have concisely reviewed the recent advancements and applications of photocatalytic polymeric composites, with special emphasis on the treatment and removal performance for organic/nonbiodegradable pollutants from wastewater. The basic principles of photocatalysis and the oxidation steps are also summarized.