scholarly journals Photocatalytic, Sonolytic and Sonophotocatalytic Degradation of 4-Chloro-2-Nitro Phenol

2013 ◽  
Vol 39 (2) ◽  
pp. 17-28 ◽  
Author(s):  
Anoop Verma ◽  
Harmanpreet Kaur ◽  
Divya Dixit
Keyword(s):  
Synergistic Effect ◽  
Organic Pollutants ◽  
Catalyst Concentration ◽  
Environmentally Friendly ◽  
Mercury Lamp ◽  
First Order ◽  
Complete Degradation ◽  
First Order Kinetics ◽  
Oxidant Concentration ◽  
Artificial Uv

Abstract The photocatalytic, sonolytic and sonophotocatalytic degradation of 4-chloro-2-nitrophenol (4C2NP) using heterogeneous (TiO2) was investigated in this study. Experiments were performed in slurry mode with artificial UV 125 watt medium pressure mercury lamp coupled with ultrasound (100 W, 33+3 KHz) for sonication of the slurry. The degradation of compound was studied in terms of first order kinetics. The catalyst concentration was optimized at 1.5 gL-1, pH at 7 and oxidant concentration at 1.5 gL-1. The results obtained were quite appreciable as 80% degradation was obtained for photocatalytic treatment in 120 minutes whereas, ultrasound imparting synergistic effect as degradation achieved 96% increase in 90 minutes during sonophotocatalysis. The degradation follows the trend sonophotocatalysis > photocatalysis > sonocatalytic > sonolysis. The results of sonophotocatalytic degradation of pharmaceutical compound showed that it could be used as efficient and environmentally friendly technique for the complete degradation of recalcitrant organic pollutants which will increase the chances for the reuse of wastewater.

Comparative study on photooxidation of methyl orange using various UV/oxidant systems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Soraya Boukhedoua ◽  
Razika Zouaghi ◽  
Oualida Nour El Houda Kaabeche
Keyword(s):  
Methyl Orange ◽  
Comparative Study ◽  
Degradation Rate ◽  
Mercury Lamp ◽  
Radical Species ◽  
First Order ◽  
First Order Kinetics ◽  
Oxidant Concentration ◽  
Pseudo First Order ◽  
Uv C

Abstract In the present work, a comparative study of the photooxidation of an aqueous solution of Methyl Orange (MeO) has been realized using H2O2 and IO3 −, BrO3 −, ClO3 −, ClO4 −, BO3 − ions in the presence of UV low pressure mercury lamp (UV-C light at λ max = 254 nm). The initial concentration of MeO in all experiments was 6 × 10−5 mol L−1. The degradation rate of MeO follows pseudo-first-order kinetics in all UV/Oxidant systems. The highest degradation rate of MeO was in the BrO3 −/UV254nm system. Different systems were compared for an oxidant concentration of 10−2 mol L−1 and the obtained results showed that decolorization followed the decreasing order: BrO 3 − /UV 254 nm  > IO 3 − /UV 254 nm  > H 2 O 2 /UV 254 nm  > BO 3 − /UV 254 nm  > ClO 3 − /UV 254 nm  = ClO 4 − /UV 254 nm  = UV 254 nm . The optimization of oxidants concentration for each process was determined (10−2 mol L−1 for IO3 − which gives almost the same k app for 5 × 10−3, 10−2 mol L−1 for BO3 − and 5 × 10−2 mol L−1 for H2O2). No degradation of MeO in presence of ClO3 − and ClO4 − because these ions do not absorb at 254 nm, therefore they do not generate radical species which degrade organic pollutants. The mineralization was also studied where it was reached 97% after 5 h of irradiation for both H2O2/UV254 nm and BO3 −/UV254 nm systems.

Effects of oxidant concentration and temperature on decolorization of azo dye: comparisons of UV/Fenton and UV/Fenton-like systems

2012 ◽  
Vol 65 (11) ◽  
pp. 1970-1974 ◽  
Author(s):  
C. Y. Kuo ◽  
C. Y. Pai ◽  
C. H. Wu ◽  
M. Y. Jian
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Azo Dye ◽  
Activation Energies ◽  
First Order ◽  
First Order Kinetics ◽  
Oxidant Concentration ◽  
Decolorization Efficiency ◽  
Pseudo First Order ◽  
Reactive Red 2

This study applies photo-Fenton and photo-Fenton-like systems to decolorize C.I. Reactive Red 2 (RR2). The oxidants were H2O2 and Na2S2O8; Fe2+, Fe3+, and Co2+ were used to activate these two oxidants. The effects of oxidant concentration (0.3–2 mmol/L) and temperature (25–55 °C) on decolorization efficiency of the photo-Fenton and photo-Fenton-like systems were determined. The decolorization rate constants (k) of RR2 in the tested systems are consistent with pseudo-first-order kinetics. The rate constant increased as oxidant concentration and temperature increased. Activation energies of RR2 decolorization in the UV/H2O2/Fe2+, UV/H2O2/Fe3+, UV/Na2S2O8/Fe2+ and UV/Na2S2O8/Fe3+ systems were 32.20, 39.54, 35.54, and 51.75 kJ/mol, respectively.

Effect of Ultrasonic Frequency on Chlorpyrifos Degradation in Sonolytic Ozonolysis

2014 ◽  
Vol 587-589 ◽  
pp. 578-581
Author(s):  
Jin Zhu ◽  
Chang Ping Zhu ◽  
Bin Wang ◽  
Run Hang Gong ◽  
Qing Gong Ren ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Degradation Rate ◽  
Degradation Kinetics ◽  
Degradation Pathway ◽  
Frequency Effect ◽  
Ultrasonic Frequency ◽  
Kinetics Parameters ◽  
First Order ◽  
First Order Kinetics ◽  
Degradation Reaction

The degradation of chlorpyrifos is investigated with the treatments of sonolysis, ozonolysis, and sonolytic ozonolysis at various frequencies. Results show that there exists frequency effect in sonolytic ozonolysis. In sonolytic ozonolysis, the maximum degradation rate is obtained at 495 kHz, and the degradation kinetics is fitted to the first-order kinetics model well. However, the most significant synergistic effect between ultrasonic and ozone is at 124 kHz. The kinetics parameters indicate that chlorpyrifos is much more labile to ultrasonic at 495 kHz, while ozone is much more soluble at 124 kHz. The hydrolysis and oxidation are deduced to contribute to the degradation reaction and the degradation pathway for chlorpyrifos degradation is proposed.

scholarly journals PHOTOCATALYTIC ACTIVITY OF HIGH-CONCENTRATION TITANIUM DIOXIDESLURRIES AT NEUTRAL PH

Anales AFA ◽  
2020 ◽  
Vol 31 (3) ◽  
pp. 77-85
Author(s):  
L. del C. Cid ◽  
C.M.C. Vera ◽  
P.A. Sorichetti
Keyword(s):  
Catalyst Concentration ◽  
Irradiation Time ◽  
Kinetic Constant ◽  
Integrating Sphere ◽  
Simultaneous Increase ◽  
Attenuation Length ◽  
High Concentration ◽  
First Order ◽  
Neutral Ph ◽  
First Order Kinetics

The properties of high-concentration titanium dioxide slurries under UV irradiation were (Evonik Aeroxide® P25) at concentrations of 0.5, 1, 1.5, 2 and 2.5 g L-1 were irradiated by a mercury lamp (254 nm). At neutral pH, within the studied concentration range, nanoparticles form agglomerates of tens of micrometers. Their size, measured by optical microscopy, increases linearly with catalyst concentration. The attenuation length of the UV radiation was measured by a spectrophotometer with an integrating sphere. The concentration of the model contaminant (Orange II) was determined by spectrophotometry at intervals of 20 minutes, during the irradiation time (6 hours). The measured values fit satisfactorily to a pseudo first order kinetics. At catalyst concentrations of 1 g L-1 and higher, the kinetic constant is (8.1 ± 0.5) x 10-3 min-1. This is explained by the diminution of the attenuation length and the simultaneous increase of the total exposed surface at higher catalyst concentrations.

Rigid and film bioplastics degradation under suboptimal composting conditions: A kinetic study

2021 ◽  
pp. 0734242X2110637
Author(s):  
Federica Ruggero ◽  
Sara Belardi ◽  
Emiliano Caretti ◽  
Tommaso Lotti ◽  
Claudio Lubello ◽  
...  
Keyword(s):  
Kinetic Study ◽  
Degradation Rate ◽  
Disintegration Process ◽  
First Order ◽  
Complete Degradation ◽  
First Order Kinetics ◽  
Degradation Rates ◽  
Imagej Software ◽  
Mesophilic Conditions

The present research investigates the degradation rate of bioplastics under various composting conditions, including suboptimal ones. Lab-scale tests were carried out setting three variables: temperature (37°C–58°C), humidity (30%–60%) and duration of the thermophilic and the maturation phases (15–60 days). The composting tests were carried out following modified guideline ISO 20200:2015 and lasted for 60 days. Bioplastics in the synthetic waste matrix consisted of Mater-Bi® film biobags and PLA rigid teaspoons. A kinetic study was performed, resulting in faster degradation rates for film bioplastics (first-order kinetics with k = 0.0850–0.1663 d−1) than for rigid (0.0018–0.0136 d−1). Moreover, film bioplastics reached a complete degradation within the 60 days of the test. Concerning the rigid products, 90% degradation would be achieved in 2–3 years for mesophilic conditions. Finally, in the undersieve of 0.5 mm some microplastics were identified with the ImageJ software, mainly relatable to rigid (PLA) bioplastics. Overall, the results disclosed that the combination of mesophilic temperatures and absence of moistening slowed down both the degradation and the disintegration process of bioplastics.

The photoconversion of gamma-hexachlorocyclohexane under UV irradiation in water, snow and ice

2013 ◽  
Vol 68 (11) ◽  
pp. 2479-2484 ◽  
Author(s):  
Honghai Xue ◽  
Xiaojian Tang ◽  
Chunli Kang ◽  
Jia Liu ◽  
Lei Shi ◽  
...  
Keyword(s):  
Chlorine Atom ◽  
Organic Pollutants ◽  
Uv Irradiation ◽  
Inorganic Ions ◽  
Kinetics Model ◽  
Inhibition Effect ◽  
First Order ◽  
First Order Kinetics ◽  
The Common ◽  
Snow And Ice

The photochemistry of organic pollutants has received increasing attention in ice and snow. In this work, the photoconversion of gamma-hexachlorocyclohexane (γ-HCH) under UV irradiation was investigated in water, snow and ice. The photoconversion rate, products and mechanisms were inspected, and the effect of inorganic ions (NO2−, NO3−, HCO3− and Fe2+) was discussed. The results showed that γ-HCH could be photoconverted in water, snow and ice, with the photoconversion rate being fastest in snow, and slowest in ice. All photoconversion could be described by the first-order kinetics model. In water, snow and ice, the common photoproducts of γ-HCH were alpha-hexachlorocyclohexane (α-HCH) and pentachlorocyclohexene. α-HCH was generated by a change in the bonding of a chlorine atom in γ-HCH; pentachlorocyclohexene was generated by the removal of a molecule of chlorine hydride from a molecule of γ-HCH. Different concentrations of NO2−, NO3− and HCO3− all inhibited the photoconversion of γ-HCH, and the inhibition effect decreased with increasing concentrations of NO2− and NO3−, but increased with the increasing concentrations of HCO3−. Different concentrations of Fe2+ promoted the photoconversion of γ-HCH in water and ice, but had little effect in snow.

scholarly journals Photocatalytic Degradation of Reactive Yellow Dye in Wastewater using H2O2/TiO2/UV Technique

2020 ◽  
Vol 21 (1) ◽  
pp. 15-21
Author(s):  
Noor A. Mohammed ◽  
Abeer I. Alwared ◽  
Mohammed S. Salman
Keyword(s):  
Degradation Rate ◽  
Rate Coefficient ◽  
Mercury Lamp ◽  
Oxidation Treatment ◽  
First Order ◽  
First Order Kinetics ◽  
Characteristic Wavelength ◽  
Color Degradation ◽  
Pseudo First Order ◽  
Ph Range

In the present study, advanced oxidation treatment, the TiO2 /UV/H2O2  process was applied to decolorisation of the reactive yellow dyes in aqueous solution. The UV radiation was carried out with a 6 W low-pressure mercury lamp. The rate of color removal was studied by measuring the absorbency at a characteristic wavelength. The effects of H2O2 dosage, dye initial concentration and pH on decolorisation kinetics in the batch photoreactor were investigated. The highest decolorisation rates were observed (98.8) at pH range between 3 and 7. The optimal levels of H2O2 needed for the process were examined. It appears that high levels of H2O2 could reduce decolorisation by scavenging the *OH. The color degradation rate decreases as the dye concentration increases. The rate coefficient (k=0.0319 min-1) of degradation, follows the pseudo-first-order kinetics.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

Biodegradation rates of aromatic contaminants in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Aromatic Hydrocarbons ◽  
Competitive Inhibition ◽  
Removal Rate ◽  
First Order ◽  
Biofilm Reactors ◽  
First Order Kinetics ◽  
Reducing Conditions ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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