Papers by Author: Manish Mishra

Abstract: The photocatalytic degradation (PCD) of three commercially textile dyes, namely Alizarin Cyanine Green G (ACG), Reactive Red 195 (RR195) and Reactive Black 5 (RB5) has been investigated using TiO₂ (Degussa P25) photocatalyst in aqueous solution under UV light. Experiments were conducted to optimize various parameters viz. amount of catalyst, initial concentration of dye and solution pH. Degradation of all the dyes was examined by using UV spectrophotometer. Photocatalytic degradation increased with increasing TiO₂ loading (in the range 0.51.5 g/L) and decreasing with increasing dye concentration (in the range 20-100 mg/L) and solution pH (in the range 4-10). Result demonstrated that the reactivity of the three dyes for TiO₂ catalyzed PCD was as follows: Reactive Red 195 > Reactive Black 5 > Alizarin cyanine Green G, respectively.

Abstract: Titanium dioxide (Titania; TiO₂) is one of the most widely used metal oxide semiconductor in the field of photocatalysis for removal of pollutants. It has been noted that titanium dioxide is a research friendly material as its physico-chemical and catalytic properties can be easily altered as per specific application. Since many years, researchers have tried to modify the properties of titanium dioxide by means of doping with metals and non-metals to improve its performance for photocatalytic degradation (PCD) applications. The doping of various metal ions like Ag, Ni, Co, Au, Cu, V, Ru, Fe, La, Pt, Cr, Ce, etc. in titanium dioxide have been found to be influencing the band gap, surface area, particle size, thermal property, etc. and therefore the photocatalytic activity in PCD. Moreover, photocatalytic activity of doped titanium dioxide has been observed in visible light range (i.e., at wavelength >400 nm). In this review, different synthesis route for doping of metal ions in titanium dioxide have been emphasised. The effect of metal dopant on the structural, textural and photocatalytic properties of titanium dioxide has been reviewed.

Abstract: Among the new oxidation methods in advanced oxidation processes, heterogeneous photocatalysis based on UV/ titanium dioxide is one of the emerging technologies for degrading and totally mineralizing toxic and highly stable carboxylic acids from waste water has attracted great attention in last decade. The aliphatic and aromatic carboxylic acids are widely used as reactants or produced as main products or byproducts in various chemical process industries. These chemical process industries generates waste water containing significant amount of carboxylic acids, which need to be removed from waste water before disposal to natural water bodies due to the environmental restrictions and their hazardous effects on flora and fauna. This paper reviews photocatalytic degradation (PCD) process for various carboxylic acids in detail, including basic mechanism of titanium dioxide, effect of carboxylic acid structure and various reaction parameters like effect of initial concentration and kinetic study, catalyst loading, pH, adsorption and deactivation of the photocatalyst. A critical analysis of the available literature has been made and some general conclusions have been drawn related to the above mentioned parameters. The photocatalytic degradation pathways for carboxylic acids are also discussed to understand this process thoroughly.