Preliminary study on optimization of pH, oxidant and catalyst dose for high COD content: solar parabolic trough collector

Abstract

In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater. Experiments have been performed on synthetic high COD wastewater for solar photocatalytic oxidation using a parabolic trough reactor. Parameters affecting the oxidation of organics have been investigated.The experimental design followed the sequence of dark adsorption studies of organics, followed by photolytic studies (in absence of catalyst) and finally photocatalytic studies in presence and absence of additional oxidant (H2O2). All the experimental studies have been performed at pH values of 2, 4, 6,8,10 and the initial pH value of the wastewater (normal pH). For photocatalytic studies, TiO2 has been used as a photocatalyst. Optimization of catalyst dose, pH and H2O2 concentration has been done. Maximum reduction of organic content was observed at the normal pH value of the wastewater (pH = 6.8). The reaction rate was significantly enhanced in presence of hydrogen peroxide. The optimum pH other than the Normal was in the alkaline range. Acidic pH was not found to be favourable for organic content reduction. pH was found to be a dominant factor affecting reaction rate even in presence of H2O2 as an additional oxidant. Also, the solar detoxification process was effective in treating a waste with a COD level of more than 7500 mg/L, which is a otherwise a difficult waste to treat. It can therefore be used as a treatment step in the high organic wastewater treatment during the primary stage also as it effectively reduces the COD content by 86%.

Facile Synthesis of Hybridized Mesoporous Au@TiO2/SnO2as Efficient Photocatalyst and Selective VOC Sensor

“…As shown in Figure (B), insignificant degradation of RhB was noted in the absence of catalysts which suggest that OH⋅ radical cannot generate to carry out the catalytic process. As the catalyst dosage was increased, RhB degradation rate was enhanced by the increased OH⋅ concentration (Figure (C)) . The corresponding first order kinematics is shown in Figure (D).…”

“…As the catalyst dos- age was increased, RhB degradation rate was enhanced by the increased OH· concentration (Figure 8(C)). [31,32] The correspond-ing first order kinematics is shown in Figure 8(D). The most favourable catalyst dosage of A-TSn was 0.3 g/L (pH 10, dye concentration 100 ppm) whereby, 99.2 % RhB dye was degraded in 35 min of illumination time.…”

Visible light induced photocatalytic reduction of metals (Cr, Cu, Ni, and Zn) and its synergism with different pH, TiO2, and H2O2 doses in simulated wastewater

“…It presumed that the reaction was performed efficiently at the solar irradiation between 600-865 W/m 2 (Tables IV and V). 14 Some replicate experimental run performed on a cloudy day, (solar irradiation 200-250 W/m 2 ), showed low metals reduction in 5 h. It is reported 23 that above a certain value (estimated to be 25 W/m 2 of UV in laboratory experiments) the reaction rate becomes proportional to the square root of UV intensity.…”

“…The composition and preparation of synthetic high inorganic wastewater used for the study is given in Table I 14 and its physicochemical characteristics are given in Table II.…”

Performance of advanced oxidation processes to treat the petroleum wastewater A review

“…A reverse effect occurs when the TiO2 concentration increases to higher than the optimum value, the degradation rate declines due to the interference of the light by the suspension (Chakrabarti & Dutta, 2004;Ehrampoosh et al, 2011). It may be due to the scattering of the light and reduction in light penetration through the effluent due to the obstruction of a large number of solid particles (Das et al, 2013;Gaya & Abdullah, 2008;Singh et al, 2013;Chan et al, 2003). This, in turn, results in a reduction of the available active sites.…”