Papers by Author: Ajay Bansal

Abstract: To overcome the water pollution problems, and to meet stringent environmental regulations, scientist and researchers have been focusing on the development of new water purification processes. One such group of new technologies is advanced oxidation processes (AOPs). Among the AOPs, titanium dioxide photocatalysis has been widely studied on lab scale by the researchers for decontamination of drinking water. In the present chapter, a conceptual as well as state-of-art review of titanium dioxide photocatalysis for water purification has been discussed.

Abstract: In the present scenario, the problem of water pollution is remarkable. The need to maintain clean water for both flora and fauna has become a major, even a critical concern. A large number of organic substances are introduced into the natural water system from various sources such as industrial effluents, agricultural runoff and chemical spills. Textiles industries specifically pollute the water sources due to the random use and discharge of various types of dyes. It may significantly affect photosynthetic activity in aquatic life and their presence in drinking water constitutes a potential human health hazard. It is therefore essential either to remove the dyes from water or to treat them in such a way so as to minimize their effects on the environment and also to decolorize the water. Various research works on different processes are reviewed and discussed in the present article. It has been observed that the advanced oxidation processes are used widely to degrade the organic compounds in water. Photocatalytic systems are effective for the degradation of many unwanted complex organic compounds through the use of efficient nanophotocatalysts activated under ultra-violet (UV) irradiation.

Abstract: The treatment of highly colored wastewater containing hazardous industrial chemicals and dyes is one of the growing needs of the present time. To meet the motive in the present work, TiO₂ was immobilized on glass slides using heat method and acrylic binder. Heat method involves the preparation of suspension of powdered TiO₂ and then brushing the suspension on the surface of glass slides. The slides were then calcined at high temperature for attachment of TiO₂ to the glass surface. The acrylic binder method of immobilization involves preparation of acrylic emulsion and using the same to attach the TiO₂ particles to the fiber glass slides. The preared films were then characterized using XRD and SEM. The photocatalytic performance of the prepared films for degradation of Acid Red 27 dye in sunlight was evaluated and compared. The films formed with the help of heat treatment method showed better dye degradation capabilities.

Abstract: nanosized titania catalyst and transition metal doped titania photocatalysts such as TiO₂/Ag, TiO₂/Cu and TiO₂/Ag/Cu were used for photocatalytic degradation of Amaranth. Doping of titania was done with impregnation method. Photocatalytic activity was checked in terms of percentages of decolorization, COD removal and TOC removal. It was found that TiO₂/Ag/Cu doped photocatalyst was more effective for Amaranth dye degradation under feasible treatment conditions. For decolorization, Amaranth took irradiation time of 210 min with UV/H₂O₂ but it took only 60 min with TiO₂/Ag/Cu doped photocatalyst. Only 29% COD and 49% TOC removal were achieved with homogeneous photodegradation, whereas with TiO₂/Ag/Cu heterogeneous photodegradation, 100% COD and 98% TOC removal was achieved in 9h for 50 ppm aqueous Amaranth solution. The relative electrical energy consumption per order of magnitude for photocatalytic degradation of Amaranth was considerably lower with TiO₂/Ag/Cu catalyst than that with UV/H₂O₂ and other combinations of doped photocatalyst. The photocatalysts were characterized using XRD and TEM analysis.