Photochemical oxidation of phenol and chlorophenol by UV/H<inf>2</inf>O<inf>2</inf>/TiO<inf>2</inf> process: A kinetic study

Abstract

In the present work, the photochemical oxidation of phenol and chlorophenol aqueous solutions in a batch recycle photochemical reactor using ultraviolet irradiation, hydrogen peroxide and Ti02 (as photocatalyst) was studied. The study showed that the combined treatment process was the most effective process under acidic conditions and showed a higher rate of degradation of phenol and chlorophenol at a very short radiation time. The reaction was found to follow the first order kinetics and was influenced by the pH, the input concentration of H202 and the dosing amount of the Ti02 photocatalyst. The results indicate maximum 74.6% and 79.8% degradation of phenol and chlorophenol respectively within 90 minutes of radiation time. The experimental results showed that the optimum conditions were obtained at a pH value of 4, with H202 concentration ranging from 200-550 mIlL, and Ti02 dosing ranging from 1-2 gIL for UVlll 202ITi02 combined system. The reactions were accompanied by the reduction of COD and generation of cr ion, which reached its maximum value at a short reaction time. Finally a rough comparison of energy consumption shows that UVlll 202ITi02 process reduced the energy consumption by 40-50% compared with the UV 111 202 and UV lTi02 processes.

Photocatalytic degradation of p-chlorophenol by hybrid H2O2 and TiO2 in aqueous suspensions under UV irradiation

“…Using 2.0e45.0 mM H 2 O 2 significantly increases the removal efficiency. These results are similar to previous reports (Barakat et al, 2005;Dixit et al, 2010;Ghaly et al, 2001;Shen et al, 1995). When the solution contains 2.0 mM H 2 O 2 , the degradation is Fig.…”

“…Previous studies have also indicated that excess catalyst will decrease the light penetration via the shielding effect of the suspended particles (Burns et al, 2002;Chiou et al, 2008b;Dixit et al, 2010;Neppolian et al, 2007;Sobczynski et al, 2004). However, compared to the other doses of TiO 2 , 1.0 g/L promotes a high removal of p-CP (79%).…”

Enhanced photocatalytic degradation of a phenolic compounds’ mixture using a highly efficient TiO2/reduced graphene oxide nanocomposite

“…They detected phenol degradation after nearly 3 h. Dixit and his group [68] studied the photochemical oxidation of phenol and p-chlorophenol by combined process of UV/H 2 O 2 /TiO 2 and achieved a maximum of 74.6 and 79.8 % degradation for phenol and pchlorophenol, respectively. In this work, higher degradation rates were measured for the different phenolic compounds using simulated sunlight.…”

Photocatalytic removal of phenol under visible light irradiation on zinc phthalocyanine/mesoporous carbon nitride nanocomposites

“…Catalytic and photocatalytic oxidation are examples of the AOP techniques. [7][8][9][10][11][12][13][14][15] Even though the thermal catalytic oxidation of phenol provides milder reaction conditions than the non-catalytic process, reactions conducted under more ambient conditions would be more desired. Photocatalytic oxidation reaction would be one of the best technologies that can solve the problem since it can be conducted at around room temperature.…”

“…For example, it was reported that TiO 2 was able to mineralise phenol under UV light irradiation. [9][10][11] However, since sunlight only consists of 5% UV light region and more than 40% visible light region, the development of heterogeneous photocatalysis applicable under visible light irradiation is highly needed. Recently, many efforts have been put into the design of visible light-active photocatalysts for organic pollutant removal.…”