Papers by Author: Vimal Gandhi

Abstract: Textile and dyes industries are generating huge amount of waste water contains significant amount of dyes which are toxic and hazardous for the environment. Recently, advanced oxidation processes (AOPs) have considerable attention because it offers an attractive method for degradation of organic compounds and color from wastewater. The present work is focused on the heterogeneous photocatalytic degradation of Alizarin Cyanine Green and Acid Orange 7 dye using UV/TiO₂ process. The degradation of dyes is strongly dependent on the various operational parameters like initial concentration of dye, pH and loading of TiO₂. The kinetics of degradation of dye in the solutions was found to pseudo first order kinetics. A statistical technique response surface methodology was employed to study the influence of various operational parameters on degradation efficiency. Three-factor-three-level Face Centered Design was used for design of experiments. For 100 mg/L concentration of Alizarin Cyanine Green and Acid Orange 7 dyes, the optimum parameters were found to be 1.2 gm/L and 1.4 gm/L TiO₂ loading for maximum degradation of 97% and 65% respectively.

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: 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.