The pH and anion effects on the heterogeneous photocatalytic degradation of o-methylbenzoic acid in TiO2 aqueous suspension

Wang, Kuo-Hua; Hsieh, Yung-Hsu; Wu, Chung‐Hsin; Chang, Chen-Yu

doi:10.1016/s0045-6535(99)00252-0

Cited by 167 publications

(77 citation statements)

References 11 publications

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“…The fouling of photocatalytic surface can be reduced by pre-treatment of water such as with ion exchange resins which have been reported to reduce the fouling and so the cost of treatment [65]. Similarly the fouling induced by sulphates and phosphates has been reported to be displaced by NaOH, KOH and NaHCO 3 [66]. However, most of studies conducted on the effect of inorganic ions are based on the model compounds and therefore do not necessarily represent their effect in real water matrix where several ions exist.…”

Section: Inorganic Ionsmentioning

confidence: 99%

A Review on the Factors Affecting the Photocatalytic Degradation of Hazardous Materials

Kumar

Gajanan

ey³

2017

MSEIJ

219

124

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The oxidation rates and efficiency of the photocatalytic system are highly dependent on a number of operational parameters that govern the photodegradation of the organic molecule. Several study have been reported the significance of operational parameter. The photodegradation depends on the some basic parameters which are concentration of substrate, amount of photocatalyst, pH of the solution, temperature of reaction medium, time of irradiation of light, the intensity of light, surface area of photocatalyst, dissolve oxygen in the reaction medium, nature of the photocatalyst, nature of the substrate, doping of metal ions and non metal and structure of photocatalyst and substrate. The photodegradation of organic compound have been studied by the several scientists and conclude the optimum conditions for the photodegradation of organic compound.The photodegradation of organic compounds was found maximum at low concentration of organic substrate with optimum amount of photocatalyst. The pH of the solution is also affect the photodegradation of organic substrate. The Titania show the maximum adsorption at low pH hence the photodegradation also found maximum at low pH. The surface area is the crucial factor for the photodegradation of organic substrate. If we are increasing the surface area of photocatalyst, the photodegradation of organic substrate increase. This is because that the number of active site increased with increasing the surface area. The amount of photocatalyst is the primary requirement of any photocatalysis process. The amount of photocatalyst should be optimum, if we take the high amount of photocatalyst the photodegradation is decreased, if we take the low amount of photocatalyst the photodegradation also decreased. The doping of metal ions and non-metal ions affect the photodegradation of organic substrate. Therefore, we have to use the metal ions which increased the positive charge on the surface of photocatalyst. The temperature and irradiation of light also affect the photodegradation of organic substrate. For the maximum photodegradation, the photocatalytic reaction should perform at room temperature not greater than 80 °C. The light of irradiation should be used which exit the electron easily from valence band to conduction band or equal to band gap energy. Keywords: A Review on the Factors Affecting the Photocatalytic Degradation of Hazardous Materials 2/10Copyright: ©2017 Kumar et al. for the removal of pollutants at high concentrations. The biological treatments are very slow, dispose large amount of sludge and required strict control of proper pH and temperature [21]. In this regard photo catalytic processes have advantages for the removal of pollutants even at low concentration for industrial waste water [22]. Moreover in photo oxidation, complete oxidation of organic pollutants take place within few hours, even at ppb level, without formation of secondary hazardous products using highly active and cheap catalysts which can be used in specially design reactor systems [23].Ti...

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Section: Inorganic Ionsmentioning

confidence: 99%

A Review on the Factors Affecting the Photocatalytic Degradation of Hazardous Materials

Kumar

Gajanan

ey³

2017

MSEIJ

219

124

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“…Decrease in COD removal efficiency could be due to magnesium and calcium salts that crystallize on the quartz sheaths that enclose UV lamps submerged in the wastewater. The resulting scale can reduce the intensity of the light and shield the water from the UV light exposure [29]. This can also be due to increase in temperature that affects H 2 O 2 solubility in wastewater and decreases the COD removal [30].…”

Section: F Integration Of Treatment Processesmentioning

confidence: 99%

Combined Biological and Advanced Oxidation Treatment Processes for COD and Color Removal of Sewage Water

Mehmood¹,

Batool²,

Qazi³

2013

IJESD

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Abstract-Wastewater (WW) generation is inevitable in rapidly growing and urbanizing societies resulting in significant damage to the quality and quantity of fresh water resources. The study was intended to harness the reuse potential of sewage WW using integrated wastewater treatment process. Composite sample of sewage WW was collected from inlet of sewage wastewater treatment plant. The WW sample was batch wise subjected to activated sludge process (ASP), ozonation, UV irradiation, H 2 O 2 oxidation and sand filtration separately for different time intervals (i.e. 0 to 60 min) and concentrations of H 2 O 2 (0.1 to 1.0 mlL -1 ), followed by the integration of all the processes at their optimum conditions. Batch experiments were performed in pyrex containers using 1.5L sample except for ASP that is 20L. Efficiencies were measured in terms of COD, color and TSS removal along with changes in pH and temperature. Biological diversity of WW was also determined using cultural techniques followed by biochemical tests. Color reduction was much higher and faster than COD in all the tested treatment processes. Ozonation was the fastest process to remove 78% color in 30 minutes however, ASP was more economical for the same efficiency but requires high hydraulic retention time (HRT). Increase in UV irradiation time reduced COD and color by 54 and 69% after 60min respectively. Sand filter efficiently removed 97% TSS with marginal reduction in COD. Integration of 4 hr ASP, 24 min ozonation and 10 min UV exposure with 1 ml L -1 H 2 O 2 dose yielded 98 and 100% COD and Color reduction respectively.

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“…The effect of pH on the photocatalytic degradation efficiency of AOPs, according to some literatures (Wang et al, 2000), is one of the major factors influencing the rate of degradation of some organic compounds (Pera-Titus et al, 2004). The degradation of phenol under UV irradiation at different pH is shown in Figure 10; Figure 9 shows that the suspension pH (without any adjustment) changed with time, during the adsorption period, no change was observed, so the influence of adsorption can be neglected.…”

Section: Effect Of Ph On the Degradation Of Phenolmentioning

confidence: 99%

“…From this model, the L-H adsorption constant and the rate constant were obtained by plotting 1/r 0 versus 1/C 0 (Wang et al, 2000).…”

Section: Kinetic Studiesmentioning

confidence: 99%

The degradation of phenol in water solution by TiO2 photocatalysis in a helical reactor

2013

Global NEST Journal

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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 (TiO2) 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 oC over a range of phenol concentrations from 2.5 to 25 mg l-1, a range of TiO2 concentrations from 0.1 to 1 g l1, a range of suspensions pH from 3 to 9. The helical reactor was operated under a continuous flow-mode. Results showed that photodegradation is an effective method for the removal of phenol from wastewaters. The efficiency of the process depends strongly on the experimental conditions. The amount of catalyst, UV irradiation time, pH and light intensity were important parameters in the degradation process. The rate constants for the different parameters (TiO2, phenol concentration) were evaluated. Kinetic studies showed that titanium dioxide photocatalyst P25 was very active in phenol degradation; we observed that 99% of pollutant was degraded after 6 hours of UV irradiation; furthermore, we observed that phenol degradation was more effective under acidic conditions than alkaline. The kinetics were described by the Langmuir- Hinshelwood (L-H) kinetic model. An overall pseudo-first order kinetic constant has been calculated for phenol conversion and values obtained in acidic pH are higher than those calculated for basic pH media.

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The pH and anion effects on the heterogeneous photocatalytic degradation of o-methylbenzoic acid in TiO2 aqueous suspension

Cited by 167 publications

References 11 publications

A Review on the Factors Affecting the Photocatalytic Degradation of Hazardous Materials

A Review on the Factors Affecting the Photocatalytic Degradation of Hazardous Materials

Combined Biological and Advanced Oxidation Treatment Processes for COD and Color Removal of Sewage Water

The degradation of phenol in water solution by TiO2 photocatalysis in a helical reactor

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