Effect of Multiwalled Carbon Nanotubes on the Photocatalytic Degradation of Methyl Orange in Aqueous Solution Under Visible Light Irradiation

Application of visible light active photocatalysis for water contaminants: A review

Organic water pollutants are ubiquitous in the natural environment arising from domestic products as well as current and legacy industrial processes. Many of these organic water pollutants are recalcitrant and only partially degraded using conventional water and wastewater treatment processes. In recent decades, visible light active photocatalyst has gained attention as a non-conventional alternative for the removal of organic pollutants during water treatment, including industrial wastewater and drinking water treatment. This paper reviews the current state of research on the use of visible light active photocatalysts, their modified methods, efficacy, and pilot-scale applications for the degradation of organic pollutants in water supplies and waste streams. Initially, the general mechanism of the visible light active photocatalyst is evaluated, followed by an overview of the major synthesis techniques. Because few of these photocatalysts are commercialized, particular attention was given to summarizing the different types of visible light active photocatalysts developed to the pilot-scale stage for practical application and commercialization. The organic pollutant degradation ability of these visible light active photocatalysts was found to be considerable and in many cases comparable with existing and commercially available advanced oxidation processes. Finally, this review concludes with a summary of current achievements and challenges as well as possible directions for further research. PRACTITIONER POINTS: Visible light active photocatalysis is a promising advanced oxidation process (AOP) for the reduction of organic water pollutants. Various mechanisms of photocatalysis using visible light active materials are identified and discussed. Many recent photocatalysts are synthesized from renewable materials that are more sustainable for applications in the 21st century. Only a small number of pilot-scale applications exist and these are outlined in this review.

Carbon nanotubes as electronic mediators combined with Bi2MoO6and g-C3N4to form Z-scheme heterojunctions to enhance visible light photocatalysis

In this paper, Z-scheme Bi₂MoO₆/CNTs/g-C₃N₄composite photocatalysts were prepared through a simple hydrothermal method. The analysis was performed by XRD, FT-IR, SEM, EDS, TEM, HRTEM, XPS, BET, UV-Vis diffuse reflectance and PL spectrums. Various analyses show that CNTs not only act as excellent charge transfer bridges, but also enable a formation of the Z-scheme of charge transfer mechanism between Bi₂MoO₆and g-C₃N₄. This process not only effectively isolates electrons and holes, but also prolongs electron-hole pair lifetimes, resulting in a substantial improvement in the photocatalytic performance of the composite photocatalyst. Best photocatalytic degradation performance was shown by Bi₂MoO₆/CNTs/g-C₃N₄composite photocatalyst under simulated sunlight, while the composite photocatalyst still maintained extremely high degradation performance in cycling tests.