Kinetic studies of photocatalytic degradation of an Azo dye by titania nanoparticles

Abstract

Purpose Dyeing and printing are important steps in textile manufacturing. After the process completion, these dyes are released in the effluent. These dyes impart an unacceptable appearance but are also toxic to the soil and water bodies. The present research has been carried out to study the rate of photocatalytic degradation of an azo dye, namely, CI Direct Green 26, using titania nanoparticles under ultra violet (UV) irradiation as a function of temperature and time. Azo dyes account for the majority of all dyestuffs are produced and extensively used in the textile, paper, food, leather, cosmetics and pharmaceutical industries. Titania nanoparticles have been found to successfully degrade these dyes in the presence of UV light. The purpose of the present paper was to study the photodegradation of azo dyes using titania nanoparticles at different temperatures and time periods. Design/methodology/approach Titania nanoparticle concentration of 0.1% (w/v) was dispersed in distilled water by sonication for 1 h in sonication bath. The of rate of degradation of Direct Green 26 dye in the titania nanoparticle dispersion, under UV-A exposure was studied at different temperatures ranging from 25°C to 65 °C for time periods ranging from 1 h to 6 h. Photocatalytic degradation tests were performed in a specially designed UV reactor chamber. Raman spectroscopy of Titania nanoparticles, dye and titania/dye mixture before and after UV exposure was carried out using Confocal Laser Dispersion Raman Microscope (Renishaw, UK) with 785 nm excitation laser. Findings Titanium dioxide is an efficient photocatalyst for decolourisation of direct dye. The photodegradation of the direct Green dye was found to follow the pseudo first-order reaction. The Arrhenius activation energy was found to be 24.8 kJ/mol with A value of 0.0013 for the photocatalytic degradation of the dye. Raman spectroscopy also confirmed the adsorption of dye on titania nanoparticle and its complete degradation on exposure to UV light. Practical implications This research highlights the application of titania nanoparticles for the effective degradation of dye in the effluent from textiles, clothing, paper and any kind of dyeing process. Azo dyes account for the majority of all dyestuffs are produced and extensively used in the textile, paper, food, leather, cosmetics and pharmaceutical industries. Titania nanoparticles have been found to successfully degrade these dyes in the presence of UV light which can be very beneficial for the effluent treatment plants in textile and other industries. Originality/value Azo dyes are one of the harmful pollutants released in textile waste water. The degradation and removal of the coloured waste in the textile effluent is an important environmental concern and needs to be investigated. The research is one of the first to investigate and understand the mechanism of the degradation of an azo dye in the presence of titania nanoparticles by Raman spectroscopy.

Synthesis and Characterization of Parthenium hysterophorus-Mediated ZnO Nanoparticles for Methylene Blue Dye Degradation

“…Te degradation of MB dye was monitored by using a UV-Vis spectrophotometer by measuring the change in absorbance of the dye alone; the dye spiked with hydrogen peroxide and the dye spiked with hydrogen peroxide and ZnO NPs at a constant time of 150 minutes. Te degradation studies of MB dye by ZnO NPs were also conducted at varying reaction conditions, including the concentration of the MB dye solution, the dosage of ZnO NPs, interaction time, pH, and temperature [37][38][39]. Te recyclability capability of ZnO NPs in the degradation of MB dye was also investigated in this study [17,[39][40][41][42].…”

“…Te kinetics of degradation of MB dye was determined by assuming a pseudo-frst-order kinetic model (equation ( 3)) and a pseudo-second-order kinetic model (equation ( 4)) [38,40,41].…”

“…where ∆H and ∆S are the change in heat and entropy of the degradation reaction, respectively. Te T is the temperature in Kelvin, and R is the universal gas constant [38,43].…”

“…Tis indicated that the ZnO NPs have the catalytic properties to degrade the MB dye [39,54]. Te degradation studies were then investigated by varying MB dye concentration, pH, ZnO NP dosage, temperature, and interaction time [37][38][39].…”

Quantum and Experimental Studies on the Adsorption Efficiency of Oyster Shells Based CaO Nanoparticles (CaONPO) Toward the Removal of MethyleneBlue Dye (MBD) from Aqueous Solution

“…K2 values had a range of 0.015 to 0.0124 g/(mg/h) and the fitness was described by R 2 as approximately equal to 0.99 Dinh et al (2021). also obtained k2 = 0.064 g/mg/min for the adsorption of MBD by UiO-66-NO2 nanoparticles, which obeyed a pseudo second order kinetic.The adsorption data for MBD onto CaONPO did not fit the pseudo first order model but obeyed the pseudo second order model with R 2 value of 0.9735.The third kinetic model considered for the adsorption of methylene blue dye is the Elovich model, which can technically be represented according to equation 9(Goyal et al 2021) 𝑢𝑛𝑖𝑡 = 𝑔/𝑚𝑔 and 𝛼 (𝑈𝑛𝑖𝑡 = 𝑚𝑔/𝑔. 𝑚𝑖𝑛) are Elovich constants which represent the capacity and the rate of adsorption respectively.…”