Bulletin of Environment, Pharmacology and Life Sciences Advanced Oxidation Process for Phenol Degradation By UV/TiO2 In Aqueous Solutions (original) (raw)
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The Effect of Dissolved Oxygen on the UV/TiO 2 Photocatalytic Degradation Mechanism of Phenol
Chemical engineering transactions, 2019
Photocatalysis is a green technology for the degradation of persistent organic compounds in water and has been successful in the removal of several water pollutants. Degradation of organic compounds in water is often accompanied by the formation of degradation by-products, which are not well researched. In this study, aromatic intermediates formed during the photocatalytic degradation of phenol were profiled in a batch system. The carbon-13 isotopic labelling technique was used to track the degradation pathway. Photocatalytic degradation of phenol was conducted in 1L solutions of phenol (20 mg/L) in ultrapure water in a batch system. Catalyst concentration was constant at 8 mg/L Titanium dioxide (TiO2). Concentration of phenol and detection of the aromatic intermediates of phenol degradation were monitored on a Waters High Performance Liquid Chromatograph (HPLC) and Gas Chromatogram- Mass Spectrometer (GC-MS), respectively. Aromatic intermediates identified during the course of phot...
Investigation of photocatalytic degradation of phenol by UV/TiO2 process in aquatic solutions
Nano-sized ZnO catalysts were prepared by a direct precipitation method under the optimal conditions (calcination of precursors at 550˚C for 120 min). The as-synthesized ZnO catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-Vis spectroscopy. The photocatalytic properties of ZnO nanoparticles were investigated via methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including the amount of ZnO catalysts, pH value of solutions, and the photodegradation temperature was thoroughly examined. In addition, the kinetic process of photocatalytic degradation of MO using nano-sized ZnO catalyst was also examined, and the degradation of MO follow the first order kinetics.
Abstract Photo-catalytic activity of Titanium dioxide (TiO2) under various irradiation conditions was explored. Experiments were conducted to investigate the effects of parameters such as pH, catalyst dosage, phenol concentration and ultra violet (UV) light intensity. This research addressed the photo degradation efficiency of phenol and the generation of hydroxyl radicals using the UV/TiO2 system. Experimental results revealed that the photo-catalytic activity of the TiO2 was higher under UV light irradiation and indicated that the removal efficiency was highest for phenol when using 0.20 wt% TiO2 dose concentrations. The maximum phenol removal was achieved by using TiO2 for industrial waste water having the initial concentrations of phenol 10 mg/L. Experimental data obtained under different conditions were fitted with kinetic models to describe the dependency of degradation rate as a function of the above mentioned parameters and pseudo-first order was found to describe the phenol degradation with high correlation coefficients compared to pseudo second order. Equilibrium data were analyzed using Langmuir-Hinshelwood kinetics. Keywords: Photo-catalysis; Phenol, Sunlight; Hydroxyl radical; TiO2; UV; Photo-catalysis; Phenol degradation
Journal of Applied Research in Water and Wastewater, 2022
Pollution from industrial effluents is more diverse and complex than municipal wastewater due to the use of thousands of new chemical compounds in industry every year. Subsequent introduction of small quantities of these compounds into water streams through industrial effluents has complicated water pollution problems and posed many challenges in removing contaminants from water. The purpose of the present study was to remove phenol contaminants from the effluent of petrochemical wastewater treatment plants using advanced photochemical oxidation method (ultraviolet/hydrogen peroxide/ozone) in a laboratory scale. The experiments were performed using UVC light, 30 % H2O2 as oxidizer and phenol (100 mg/L). The effective parameters studied in phenol removal included pH, H2O2 concentration, solution temperature and UVC irradiation time. The experimental results showed an increase in phenol removal efficiency with increasing H2O2 concentration up to 400 mg/L while decreasing with increasing oxidizer concentration to 500 mg/L, thus suggesting a concentration of 400 mg/L as the optimal value. Using a flow rate of 200 mg/L of ozone for 80 min, by optimizing other conditions, increased the phenol removal efficiency by 98 %. The phenol removal efficiency was much higher at acidic conditions than at alkaline and neutral ones. The phenol content decreased significantly with increasing contact time. In other words, prolonged contact time increased the phenol removal efficiency in the tested sample. The highest phenol removal efficiency (75.7 %) occurred at the pH value of 4 and the phenol removal efficiency in the sample decreased with increasing pH value. Prolonged contact time caused more phenol concentration to be removed from the test sample, so that 69.8 % of the phenol concentration in the sample was reduced. The results of this study showed that advanced oxidation reduced the phenol content in the analyzed sample. To conclude, the advanced oxidation methods can be useful in the process of treating petrochemical wastewater and effluent of units containing toxic aromatic compounds such as phenol.
Investigation of Phenol Removal in Aqueous Solutions Using Advanced Photochemical Oxidation (APO)
WATER AND …, 2010
Most organic compounds are resistant to conventional chemical and biological treatments. For this reason, other methods are being studied as alternatives to the biological and classical physico-chemical processes. In this study, advanced photochemical oxidation (APO) processes (UV, UV/H 2 O 2 , UV/H 2 O 2 /Fe(II), and UV/H 2 O 2 /Fe(III)) were investigated in lab-scale experiments for the degradation of phenol in an aqueous solution. A mediumpressure 300 watt (UV-C) mercury ultraviolet lamp was used as the radiation source and H 2 O 2 30% as the oxidant. Phenol (initial concentration= 0.5 mmol/L) was selected as the model due to its high use and application. Some important parameters such as pH, H 2 O 2 input concentration, iron catalyst concentration, the type of iron salt, and duration of UV radiation were studied based on the standard methods. The results showed that the Photo-Fenton process was the most effective treatment under acidic conditions producing a higher rate of phenol degradation over a very short radiation time. The process accelerated the oxidation rate by 4-5 times the rate of the UV/H 2 O 2 process. The optimum conditions were obtained at a pH value of 3, with a molar ratio of 11.61 for H 2 O 2 /Phenol and molar ratios of 0.083 and 0.067for Iron/H 2 O 2 in the UV/H 2 O 2 /Fe (II) and the UV/H 2 O 2 /Fe (III) systems, respectively.
Efficiency removal of phenol, lead and cadmium by means of UV/TiO2/H2O2 processes
International Journal of Environmental Science & Technology, 2007
A variety of processes can be used in treatment of industrial wastewaters. The relatively newest of which is photo catalysis with titanium dioxide which may also be used plus hydrogen peroxide to improve the treatment rate. In this study, photo catalysis/ hydrogen peroxide processes had been employed for the removal of phenol, lead and cadmium by three different pHs of 3.5, 7 and 11. The treatment tests were also accomplished without UV irradiation. In both experiments, the variables were pH and concentrations of reagent chemicals, but the detention time was kept constant (180 min). Results indicated that the optimum efficiencies of phenol and Cd removal were 76 % and 97.7 % at pH=11, respectively, and for lead, it was 98.8% in all pHs. In other words, no pH dependency was regarded for lead treatment. These results were all obtained by simultaneous use of UV irradiation with 3 mL/L H 2 O 2 and 0.8 g/L TiO 2 . Finally, the best pH for treatment, when all the three contaminants are presented is considered to be at 11. These results should be regarded by all industrial treatment plants which have experienced the problem of these three special contaminants in their effluents.
THE DEGRADATION OF PHENOL IN WATER SOLUTION BY TiO2 PHOTOCATALYSIS IN A HELICAL REACTOR
Heterogeneous photocatalysis is an advanced oxidation process (AOP) which has been widely studied by numerous researchers in the world and is used to degrade or remove a wide range of pollutants in water and air. The photocatalytic oxidation and mineralization of phenol in aqueous catalyst suspensions of titanium dioxide (TiO 2 ) Degussa P25 (80% anatase, 20% rutile) has been carried out in a helical reactor. The photodegradation was investigated using two kinds of high pressure mercury irradiation lamps one emitting at 254 nm (15 Watts) and the other emitting at 365 nm (400 Watts). The effects of the recirculation flow, source of withdrawal, initial phenol concentration, amount of catalyst, suspension pH and light intensity on photodegradation of phenol were investigated. These parameters were studied to find the optimal conditions for a complete and fast oxidation of this organic compound. Kinetic experiments were performed at 32 o C over a range of phenol concentrations from 2.5 to 25 mg l -1 , a range of TiO 2 concentrations from 0.1 to 1 g l 1 , a range of suspensions pH from 3 to 9. The helical reactor was operated under a continuous flow-mode.
Photocatalytic degradation of phenol
Environmental Monitoring & Assessment, 2003
In this study photocatalytic degradation of phenol in the presence of UV irradiated TiO2 catalyst and H2O2 was investigated. Effects of TiO2 and H2O2 concentrations and pH on photocatalytic degradation were examined. The rate constants for photocatalytic degradation were evaluated as a function of TiO2 and H2O2 concentrations and pH of the solution. It was found that photodegradation is an effective method for the removal of phenol and disappearance of phenol obeyed first order kinetics. The amount of CO2 produced during photocatalytic degradation was corresponding to the complete mineralization. Photodegradation can be an alternative method for the treatment of phenol containing wastewaters.
In recent years, there has been an enormous amount of research and development in the area of heterogeneous photocatalytic water purification process due to its effectiveness in degrading and mineralising the recalcitrant organic compounds as well as the possibility of utilising the solar UV and visible spectrum. One hundred and twenty recently published papers are reviewed and summarised here with the focus being on the photocatalytic oxidation of phenols and their derivatives, predominant in waste water effluent. In this review, the effects of various operating parameters on the photocatalytic degradation of phenols and substituted phenols are presented. Recent findings suggested that different parameters, such as type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidising agents/electron acceptors, mode of catalyst application, and calcination temperatures can play an important role on the photocatalytic degradation of phenolic compounds in wastewater. Extensive research has focused on the enhancement of photocatalysis by modification of TiO 2 employing metal, non-metal and ion doping. Recent developments in TiO 2 photocatalysis for the degradation of various phenols and substituted phenols are also reviewed.
Photocatalytic degradation of phenol and phenolic compounds
Journal of Hazardous Materials, 2007
Due to the toxicity effects and endocrine disrupting properties of phenolic compounds, their removal from water and wastewater has gained widespread global attention. In this study, the photocatalytic degradation of phenolic compounds in the presence of titanium dioxide (TiO 2) nano-particles and UV light was investigated. A full factorial design consisting of three factors at three levels was used to examine the effect of particle size, temperature and reactant type on the apparent degradation rate constant. The individual effect of TiO 2 particle size (5, 10 and 32 nm), temperature (23, 30 and 37 °C) and reactant type (phenol, o-cresol and m-cresol) on the apparent degradation rate constant was determined. A regression model was developed to relate the apparent degradation constant to the various factors. The largest photocatalytic activity was observed at an optimum TiO 2 particle size of 10 nm for all reactants. The apparent degradation rate constant trend was as follows: o-cresol > m-cresol > phenol. The ANOVA data indicated no significant interaction between the experimental factors. The lowest activation energy was observed for o-cresol degradation using 5-nm TiO 2 particles. A maximum degradation rate constant of 0.0138 min −1 was recorded for o-cresol at 37 °C and a TiO 2 particle size of 13 nm at a D-optimality value of approximately 0.98. The response model adequately related the apparent degradation rate constant to the factors within the range of factors under consideration.