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Vol_IV_Issue_IV_Article_8.pdf

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Thakare, et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945

Research Paper DEGRADATION OF BRILLIANT GREEN DYE USING

CAVITATION BASED HYBRID TECHNIQUES

Y D Thakare*, Prof. Mrs. S M Jadhav

Address for Correspondence

Chemical Engineering Department, Bharati Vidyapeeth Deemed University College of Engineering, Pune, 411043, India.

ABSTRACT

In the present work degradation of brilliant green has been studied using combination of acoustic cavitation and various advance oxidation processes (AOP’s). It includes combination of acoustic cavitation with hydrogen peroxide (H2O2), ultraviolet (UV) light and photocatalytic process using catalyst (Nb2O5). Degradation of brilliant green has been studied for initial concentration of brilliant green (10, 20 and 30 ppm), different sonication power (250, 500 and 750 W), different dosage of H2O2 (217, 286 and 365 mg/L) and different dosage of Nb2O5 catalyst (22, 65, 108 and 217 mg/L).

The kinetic study indicated that the degradation rate of the brilliant green dye fitted to first order kinetics for all the process studied. It has also observed that cavitational based combined techniques are more effective as compared to individual process.

KEYWORDS – Brilliant green (BG), Ultrasound sonication (US), US + H2O2, UV + Nb2O5, US + UV + Nb2O5.

INTRODUCTION

Textile and paper industry is one of the largest water consuming and water polluting industry as large amount of dyes are likely to be discharged into waste streams. The textile/paper industry and consequently its wastewater have been increasing exponentially with the ever increasing demands [1]. If these wastewaters are discharged to the environment without any treatment, these dyes can remain in the environment for an extended period of time due to their high stability to light and temperature. The presence of even very low concentrations of dyes in effluent is highly undesirable. Depending on the exposure time and dye concentration, dyes can have acute and/or chronic effects on exposed organisms. They also affect the absorption and reflection of sunlight through water, reduce oxygen solubility and threaten the photosynthetic activity of aquatic plants and algae. The effect in reduction in the oxygen levels interferes with the growth of bacteria such that they become inefficient in biologically degrading impurities in the water and hence risk the food chain. These reasons make the effective elimination of reactive dyes from effluents of textile industries very important before release into the environment [1, 2]. The brilliant green dye used in the investigation is triphenyl nitrogen containing cationic dye. The exact structure of the brilliant green dye has also been given in Fig. 1. Brilliant green is chemically described as ammonium, 4-(p-diethylamino)-alpha- (phenylbenzylidene) (C27H34N2O4S) with λmax of 625 nm and molecular weight of 482g mol-1.

Fig. 1 Structure of brilliant green

The use of brilliant green (BG) dye has been banned in many countries due to its carcinogenic nature [1]. It is used as a dye to color synthetic fibers and silk biological stain, dermatological agent, veterinary medicine, and as an additive to poultry feed to inhibit propagation of mold, intestinal parasites and fungus. It is also extensively used in textile dying and paper printing. It is considered highly toxic for humans and animals because it can cause permanent injury to eyes. It also causes irritation to the respiratory tract that leads to cough and shortness of breath. It can

cause irritation to the gastrointestinal tract, which also results in nausea, vomiting and diarrhea in human beings [9].

Number of methods have been investigated for degradation of dye waste water such as chemical oxidation and reduction, chemical precipitation and flocculation, photolysis, adsorption, ion pair extraction, electrochemical treatment, advanced oxidation, cavitation techniques etc. [3]. Cavitation is the formation of vapour cavities in a liquid ("bubbles" or "voids") that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities. Cavitational bubble collapse, H2O undergoes thermal dissociation within the vapor phase to give hydroxyl radical and hydrogen atoms [4]. Advance oxidation treatment methods are widely used for dye degradation, as they require low quantities of oxidant and economical. In the oxidation process, dye molecules are oxidized and decomposed to lower molecular weight species such as aldehydes, carboxylates, sulphates and nitrogen, the ultimate goal still remain to degrade them to carbon dioxide and water. Various types of oxidant including chlorine, hydrogen peroxide, ozone and chlorine dioxide are used for colour removal from wastewater [5].

Cavitation is the upcoming techniques that can be used for degradation of dye. It can be described as the formation of nuclei, growth and collapse of bubbles in liquid, releasing large magnitudes of energy. The collapse of the bubbles induces localized supercritical conditions, i.e. high temperature and pressure condition (about of 1000 atm pressure and about 5000 0K temperature). The local effects of cavitation include generation of free radicals, hot spots and intense turbulence coupled with liquid circulation currents; the conditions being quite favorable for oxidation of pollutants. During cavitational bubble collapse, H2O undergoes thermal dissociation within the vapor phase to give hydroxyl radical and hydrogen atoms. In water and wastewater treatment applications, organic pollutants may be destroyed either in the cavitation bubble itself by pyrolytic decomposition (if the compounds are hydrophobic), at the interfacial sheath between the gaseous bubble and the surrounding liquid or in the bulk solution via oxidative degradation by hydroxyl radicals [6, 7]. Cavitation processes [1, 3] have been reported in the literature for the degradation of brilliant green.

Int J Adv Engg Tech/IV/IV/Oct-Dec.,2013/31-36

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