scholarly journals Investigation of the effect of operational parameters and SnO2-coupling on the photocatalytic activity of TiO2

2013 ◽  
Vol 15 (4) ◽  
pp. 551-559
Keyword(s):  
Hydrogen Peroxide ◽  
Photocatalytic Activity ◽  
Light Intensity ◽  
Model Compound ◽  
Batch Reactor ◽  
Coupled System ◽  
Operational Parameters ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order

<p>The effect of different operational parameters in UV/TiO2 process, such as initial dye concentration (20-50 mg l-1), light intensity (8-45 W m-2), pH (2.83-10.22), hydrogen peroxide concentration (100-500 mg l-1), temperature (21-45 ˚C) and photocatalyst concentration (150-900 mg l-1) were investigated on the decolorization of Acid Yellow 23 as a model compound from monoazo textile dyes. The apparent first-order rate constants (kap) were evaluated which confirms pseudo first-order kinetics. kap increased with the enhancement of pH, light intensity and temperature. A desired concentration found for hydrogen peroxide (400 mg l-1) and photocatalyst concentration (750 mg l-1). The SnO2 photocatalyst was not as effective as TiO2 but had the same desired concentration (750 mg l-1). Then TiO2+SnO2 suspensions (375+375 mg l-1) as photocatalysts were employed for decolorization at different solution thicknesses. The results showed that the coupled particles were not much different from single TiO2 system at the solution thickness of 4.5 cm in a batch reactor. But the coupled system was more effective when the solution thickness was reduced to 2.5 cm. Over 90% of decolorization occurs at the solution thickness of 1.1 cm after 30 min of irradiation while 90% decolorization takes place at the solution thickness of 4.5 cm after 100 min of irradiation.</p>

scholarly journals Use of semi-conducting bismuth sulfide as a photocatalyst for degradation of rose bengal

2011 ◽  
Vol 30 (2) ◽  
pp. 229 ◽  
Author(s):  
Shweta Sharma ◽  
Rakshit Ameta ◽  
R. K. Malkani ◽  
Suresh C. Ameta
Keyword(s):  
Light Intensity ◽  
Rose Bengal ◽  
Bismuth Sulfide ◽  
Optimum Conditions ◽  
First Order ◽  
First Order Kinetics ◽  
Degradation Of Dyes ◽  
Textile Dyeing ◽  
Rate Of Reaction ◽  
Pseudo First Order

Different methods have been adopted for the removal and degradation of dyes from effluents of textile, dyeing and printing industries. These methods have their own merits and drawbacks. In the present investigation, bismuth sulfide has been used as a photocatalyst for the degradation of rose Bengal. The effect of different parameters like the pH, concentration of dye solution, amount of semiconductor and light intensity on the rate of reaction has been investigated. The reaction follows pseudo-first order kinetics. The optimum conditions were obtained as: [rose Bengal] = 1.60·10–5 M; Bi2S3 = 0.10 g; pH = 8.5, and light intensity = 50.0 mW·cm–2. The rate constant was 4.68·10–5 sec–1. A mechanism has been proposed for the degradation of rose Bengal involving hydroxyl radicals.

scholarly journals The Continuous Decolorization of Reactive Yellow Dye using Advanced Oxidation Reactors

2020 ◽  
Vol 21 (2) ◽  
pp. 1-6
Author(s):  
Noor Abdul Ameer Mohammed ◽  
Abeer I. Alwared ◽  
Mohammed S. Salman
Keyword(s):  
Batch Reactor ◽  
Low Cost ◽  
Advanced Oxidation ◽  
Chemical Degradation ◽  
Continuous Reactor ◽  
Flow Rates ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order ◽  
Maximum Removal

The reactive yellow azo dye (λmax = 420 nm) is widely utilized for textile coloring due to its low-cost stability and tolerance properties. Treatment of dye-containing wastewater by traditional methods is usually inadequate because of its resistance to biological and chemical degradation. From this research, the continuous reactor of an advanced oxidation method supported the use of H2O2/TiO2/UV to remove the coloration of the reactive yellow dye from the discharge. At constant best conditions obtained from the batch reactor tests pH=7, H2O2 dosage = 400 mg/l and TiO2=25mg/l , the aqueous solutions were tested in the continuous reactor at different dye concentration and different flow rates . The maximum removal efficiency was found to be 91.552% obtained at the flow rate 5 l/h, also the results of decomposition information proved that method was pseudo-first-order kinetics.  

Effects of operational parameters on decolorisation of C.I. Reactive Black 5 in UV/TiO2 system

2011 ◽  
Vol 63 (5) ◽  
pp. 1032-1036 ◽  
Author(s):  
C. H. Wu ◽  
C. Y. Kuo ◽  
P. K. A. Hong
Keyword(s):  
Linear Relationship ◽  
Rate Constants ◽  
Reactive Black 5 ◽  
Operational Parameters ◽  
Light Power ◽  
First Order ◽  
Photodegradation Efficiency ◽  
First Order Kinetics ◽  
Pseudo First Order ◽  
Decreasing Ph

This study utilises a UV/TiO2 system to decolorise C.I. Reactive Black 5 (RB5). The effects of TiO2 dosage, pH, RB5 concentration and light power on the decolorisation efficiency using the UV/TiO2 system were determined. IO4− was employed as an oxidant to increase the photodegradation efficiency of UV/TiO2. The decolorisation rate constants (k) of RB5 in the UV/TiO2 system are consistent with pseudo-first-order kinetics. The k values of 0.1, 0.5, 1.0 and 2.0 g/l TiO2 were 0.53, 0.52, 0.69 and 0.68 h−1, respectively. The rate constant increases with decreasing pH from 10 to 4. The decolorisation rate approximates linear relationship with RB5 concentration, as given by k=1.05[1/RB5]0.98; it varies nonlinearly with light power, as given by k=0.178[power]0.63. The experimental results reveal that the rate of decolorisation obtained using UV/TiO2/IO4− exceeds that obtained using UV/TiO2.

scholarly journals Use of zirconium phosphate system as a photocatalyst: Photobleaching of tolonium chloride

2008 ◽  
Vol 27 (2) ◽  
pp. 133 ◽  
Author(s):  
O. P. Panwar ◽  
Anil Kumar ◽  
Rameshwar Ameta ◽  
Suresh C. Ameta
Keyword(s):  
Water Pollution ◽  
Light Intensity ◽  
Zirconium Phosphate ◽  
Aquatic Life ◽  
First Order ◽  
First Order Kinetics ◽  
The World ◽  
Pseudo First Order ◽  
Phosphate System ◽  
Tolonium Chloride

Water pollution due to effluents from dyes and printing industries poses a serious problem for aquatic life. Photocatalysis has attracted the attention of chemists all over the world because it is an efficient and ecofriendly process to combat the problem of water pollution. Photocatalytic bleaching of tolonium chloride on zirconium phosphate was carried out in presence of light. The progress of the reaction was monitored spectrophotometrically, and it follows pseudo first order kinetics. The effect of variation of different parameters, like concentration of tolonium chloride, pH, amount of semiconductor and light intensity on the rate of bleaching, was also studied. A tentative mechanism for the photocatalytic bleaching of tolonium chloride has been proposed.

Remarkable Sunlight Photocatalytic Activity due to Synergetic Effect of ZnO with Cu

2017 ◽  
Vol 727 ◽  
pp. 388-394 ◽  
Author(s):  
Wei Liang Wang ◽  
Chuan Xi Yang ◽  
Feng Zhang ◽  
Ping Li ◽  
Guan Wei Cui
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Activity ◽  
Synergetic Effect ◽  
Weight Ratio ◽  
Heterogeneous Photocatalysis ◽  
Zno Nanorod ◽  
Sunlight Irradiation ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order

The ZnO nanorod was synthesized by the hydrothermal method, and Cu/ZnO nanorod was synthesized by modifying the prepared ZnO nanorod. The TEM was used to characterize the morphology and microstructure for ZnO and Cu/ZnO nanorod. The length of nanorod ZnO was about 700-800 nm, and the diameter about 40-50 nm. There was no change of ZnO in length and diameter when doped with Cu. The degradation of methylene blue (MB) in an aqueous solution under sunlight irradiation was carried out to evaluate the photocatalytic activity. The Cu/ZnO nanorod shows significantly higher photocatalytic activity (99.91%) than ZnO nanorod (89.66%) under sunlight irradiation. The degradation of MB accords with pseudo-first order kinetics, and the appear rate constants kapp of 7% Cu/ZnO nanorod was about 3 times higher than ZnO nanorod. The synergetic effect between ZnO nanorod and Cu on the photocatalytic degradation of MB exists clearly for all the nanorods, and the optimum synergetic effect was found at a weight ratio of 7 wt % (Cu/ZnO). It hoped our works could provide valuable information on the synthesis and application of ZnO-based heterogeneous photocatalysis.

In-vitro Kinetic Hydrolysis Study of Metronidazole Derivatives with Carvacrol and Eugenol Using Validated RP-HPLC Method

2020 ◽  
Vol 16 ◽  
Author(s):  
M. Alarjah
Keyword(s):  
Half Life ◽  
Hplc Method ◽  
Hydrolysis Rate ◽  
First Order ◽  
First Order Kinetics ◽  
Rp Hplc ◽  
Pharmacokinetic Properties ◽  
Pseudo First Order ◽  
Kinetic Hydrolysis

Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic properties of some active drugs. Much effort was made to develop metronidazole prodrugs to enhance antibacterial activity and or to improve pharmacokinetic properties of the molecule or to lower the adverse effects of metronidazole. Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro metronidazole molecules that were developed earlier were evaluated in-vitro. The kinetic hydrolysis rate constants and half-life time estimation of the new metronidazole derivatives were calculated using the validated RP-HPLC method. Method: Chromatographic analysis was done using Zorbbax Eclipse eXtra Dense Bonding (XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient elution, at 1ml/min flow rate. The method was fully validated according to the International Council for Harmonization (ICH) guidelines. The hydrolysis process carried out in an acidic buffer pH 1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37ºC. Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and 5.9- 8.5 hr., respectively. Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to conduct an in-vivo study for the metronidazole derivatives with monoterpenes and eugenol.

Multifactorial optimization of the decolorisation parameters of wastewaters resulting from dyeing flowers

2009 ◽  
Vol 59 (7) ◽  
pp. 1361-1369 ◽  
Author(s):  
Edison Gil Pavas ◽  
Miguel Ángel Gómez-García
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Matter ◽  
Experimental Design ◽  
Order Reaction ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Effluent Standards ◽  
Degradation Of Dyes ◽  
Pseudo First Order ◽  
Dyes Mixture

This work deals with the treatment of the wastewaters resulting from the process of dyeing flowers. In some local cases for growing flowers near to Medellín (Colombia), wastewater color was found to be one of the main problems in meeting local effluent standards. Wastewaters were treated by photodegradation process (which includes photocatalysis) to achieve the degradation of dyes mixture and organic matter in the wastewater. A multifactorial experimental design was proposed, including as experimental factors the following variables: pH, and the concentration of both catalyst (TiO2) and hydrogen peroxide (H2O2). According to the obtained results, at the optimized variables values, it is possible to reach a 99% reduction of dyes, a 76.9% of mineralization (TOC) and a final biodegradability of 0.834. Kinetic analysis allows proposing a pseudo first order reaction for the reduction, the mineralization, and the biodegradation processes.

New insights on the UV/TiO2 photocatalytic treatment of thiomersal and its 2-sulfobenzoic acid product

2021 ◽  
Vol 02 ◽  
Author(s):  
Emmanuel M. de la Fournière ◽  
Jorge M. Meichtry ◽  
Graciela S. Custo ◽  
Eduardo A. Gautier ◽  
Marta I. Litter
Keyword(s):  
Degradation Products ◽  
Acidic Ph ◽  
Cosmetic Products ◽  
Acid Product ◽  
First Order ◽  
First Order Kinetics ◽  
Photocatalytic Destruction ◽  
Pseudo First Order ◽  
Mineralization Degree ◽  
Suitable Technique

Background: Thiomersal (TM), a complex between 2-mercaptobenzoic acid (2-MBA) and ethylmercury (C2H5Hg+), is an antimicrobial preservative used in immunological, ophthalmic, cosmetic products, and vaccines. Objective: TM has been treated by UV/TiO2 photocatalysis in the presence or absence of oxygen at acidic pH. C2H5Hg+, 2-MBA, and 2-sulfobenzoic acid (2-SBA) were found as products. A 2-SBA photocatalytic treatment was undertaken to study sulfur evolution. Methods: Photocatalytic runs were performed using a UVA lamp (λmax = 352 nm), open to the air or under N2. A suspension of the corresponding TM or 2-SBA salt and TiO2 was prepared, and pH was adjusted. Suspensions were stirred in the dark for 30 min and then irradiated. TM, 2-MBA, 2-SBA, and C2H5Hg+ were quantified by HPLC, sulfur by TXRF, and the deposits on the photocatalyst were analyzed by chemical reactions. The mineralization degree was followed by TOC. Sulfate was determined using BaCl2 at 580 nm. Results: Photocatalytic destruction of TM and total C2H5Hg+ was complete under N2 and air, but TM degradation was much faster in air. The evolution of TM and the products followed a pseudo-first-order kinetics. Conclusion: TiO2-photocatalytic degradation is a suitable technique for the treatment of TM and its degradation products. In contrast to other organomercurial compounds, TM degradation is faster in the presence of O2, indicating that the oxidative mechanism is the preferred pathway. A significant TM mineralization (> 60%, NPOC and total S) was obtained. TM was more easily degraded than 2-SBA. Sulfate was the final product.

Chemical effects induced by gas–liquid jet flow

2022 ◽  
Author(s):  
Zhiliang Zhang ◽  
Jiaqi Lu ◽  
Bingqian Lv ◽  
Wei Liu ◽  
Shuyuan Shen ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Jet Flow ◽  
Reaction Process ◽  
Liquid Jet ◽  
First Order ◽  
First Order Kinetics ◽  
Chemical Effects ◽  
Pseudo First Order

The gas-liquid jet flow was proved to be capable of inducing chemical consequences which can lead to the decomposition of methylene blue (MB). The reaction process follows a pseudo-first-order kinetics....

Hydrogen Peroxide Decay in Waters with Suspended Soils: Evidence for Biologically Mediated Processes

1990 ◽  
Vol 47 (5) ◽  
pp. 888-893 ◽  
Author(s):  
William J. Cooper ◽  
Richard G. Zepp
Keyword(s):  
Hydrogen Peroxide ◽  
Natural Water ◽  
Water Samples ◽  
First Order ◽  
Natural Water Samples ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Chemical Sterilization ◽  
Pseudo First Order ◽  
Catalyzed Oxidation

Hydrogen peroxide decay studies have been conducted in suspensions of several well-characterized soils and in natural water samples. Kinetic and product studies indicated that the decay was biologically-mediated, and could be described by pseudo first-order rate expressions. At an initial H2O2 concentration of 0.5 μM, the hydrogen peroxide half-life varied from 1 to 8 h. The decay was inhibited by thermal and chemical sterilization of the soils. Peroxidase activity was inferred in several natural water samples, where the suspended particles catalyzed the oxidation of p-anisidine by hydrogen peroxide. The mass spectrum of the major reaction product indicated that it was the dimer, possibly benzoquinone-4-methoxyanil, a product that also was observed from the horseradish peroxidase-catalyzed oxidation of p-anisidine by hydrogen peroxide.

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