In this paper we are reporting the accelerated sonophotocatalytic degradation of Reactive Red (RR) 198 dye under visible light using dye sensitized TiO(2) activated by ultrasound. The effect of sonolysis, photocatalysis and sonophotocatalysis under visible light has been examined to study the influence on the degradation rates by varying the initial substrate concentration, pH and catalyst loading to ascertain the synergistic effect on the degradation techniques. Ultrasonic activation at 47kHz contributes through cavitation leading to the splitting of H(2)O(2) produced by both photocatalysis and sonolysis. This results in the formation of oxidative species, such as singlet oxygen ((1)O(2)) and superoxide (O2-*) radicals in the presence of oxygen. Sonication increases the amount of reactive radical species, inducing faster oxidation of the substrate and degradation of intermediates and also the deaggregation of the photocatalyst which are responsible for the observed synergy. Further, the photocatalytic activity of RR 198 dye sensitized TiO(2) is demonstrated by the degradation of phenol under visible light and ultrasound. A comparative study using TiO(2), Hombikat UV 100 and ZnO was also carried out.

Pd and Ru nanoparticles supported on graphene oxide (GO) [Pd@GO and Ru@GO] and bimetallic [Pd/Ru@GO] were prepared and well characterized by XRD, FT-IR, EDS, TEM, XPS and ICP-AES analyses. The prepared nano-catalysts were tested for hydrodeoxygenation (HDO) of lignin monomer molecules – vanillyl alcohol and vanillin. In comparison with previously reported methods, Ru@GO and bimetallic Pd/Ru@GO catalysts showed high activity and selectivity, under milder conditions, at room temperature and 145 psi H₂ pressure, for the formation of p-creosol, a value added product, as a potential future biofuel with antibacterial and anti-insecticidal properties. The multifold advantages of both these catalysts are in terms of reduced catalyst loading with a lower metal content and ambient temperture conditions resulting in higher conversion of the starting material. Furthermore, the efficacy of the developed methodology using Ru@GO and bimetallic Pd/Ru@GO catalysts under the optimized conditions was tested on the phenolic components of commercial lignin obtained by photo-catalytic fragmentation using TiO₂, to obtain a mixture after HDO which contained vanillyl alcohol and p-creosol among others, as indicated by HPLC-MS analysis.

This review is on current advancements in IL-mediated synthesis of TiO ₂ , and the potential for future research in this area.

Nanocrystalline undoped, N-doped, N and metal codoped titania with different particle size, surface area, anatase phase content, crystallinity, band gap and zeta potential were synthesized by the sol–gel method. The photocatalytic activities of the synthesized TiO₂ powders were compared by employing four different Reactive dyes. The order of photocatalytic activity observed for Reactive Red 198 dye (RR 198) was undoped = N,Cu codoped = N-doped > N,Fe codoped TiO₂, Reactive Blue 4 dye (RB 4) was N,Cu codoped > N,Fe codoped > N-doped > undoped TiO₂, Reactive Black 5 dye (RB 5) was N,Cu codoped* > undoped > N-doped > N,Fe codoped TiO₂ and negligible degradation was observed for Reactive Orange 16 dye (RO 16). In this paper, the anomalous trend of the photocatalytic activity of various photocatalysts for the degradation of a particular class of dyes has been observed and accounted for based upon three parameters: mechanism of degradation, physicochemical properties of the catalyst and adsorption behavior based on the zeta potential. It was concluded that apart from these parameters, the substrate-specificity of the catalyst is also of equal importance in developing new catalysts for the photodegradation of dyes present in textile effluents.

Ferrites are important magnetic materials used in electronic devices. Nanocomposites of ferrites with TiO₂, SiO₂ and carbon quantum dots have gained recent interest due to their unique advantages, such as high chemical stability, surface-active sites, high specific surface area, non-toxicity, excellent optical properties, and tunable porosity. In the present review, general and adaptable coprecipitation, sol–gel, hydrothermal, solvothermal, and Stöber methods for the fabrication of nanocomposites are discussed. These materials offer the advantage of magnetic recovery and superior photocatalytic performance. The potential of nanocomposites to act as photocatalysts to eliminate organic pollutants and microbes from water is discussed. Mechanisms involved in these applications are also elaborated upon. The review provides a detailed study of recent applications and future perspectives of nanocomposites in sustainable water treatment.