scholarly journals Photo-Fenton Oxidation of Methyl Orange Dye Using South African Ilmenite Sands as a Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1452
Author(s):  
Alicia Levana Butt ◽  
John Kabangu Mpinga ◽  
Shepherd Masimba Tichapondwa
Keyword(s):  
Methyl Orange ◽  
South African ◽  
Degradation Kinetics ◽  
Intermediate Formation ◽  
Degradation Pathway ◽  
Catalyst Loading ◽  
Total Organic Carbon Removal ◽  
Rate Of Reaction ◽  
Iron Leaching ◽  
Acidic Conditions

In this study, the viability of South African ilmenite sands as a catalyst in the photo-Fenton-like degradation of methyl orange (MO) dye was investigated. The mineralogy and other properties of the material were characterized. Complete decolorization occurred under acidic conditions (pH < 4) in the presence of ilmenite and H2O2. Light irradiation accelerated the rate of reaction. Parameter optimization revealed that a pH of 2.5, UVB irradiation, 2 g/L catalyst loading, and a hydrogen peroxide concentration of 1.0 mM were required. Under these conditions, complete decolorization was observed after 45 min. Degradation kinetics were best described by the pseudo-first order (PFO) model. Rate constants of 0.095 and 0.034 min−1 were obtained for 5 and 20 mg/L MO concentrations, respectively. A 37% total organic carbon removal was observed after 60 min. This suggests a stepwise MO degradation pathway with intermediate formation rather than complete mineralization. Although iron leaching was detected, the mineralogy of the catalyst recovered after the reaction was similar to the fresh catalyst.

scholarly journals Esterification of palmitic acid with epichlorohydrin on anion exchange resin catalyst

2007 ◽  
Vol 5 (3) ◽  
pp. 715-726 ◽  
Author(s):  
Emil Muresan ◽  
Spiridon Oprea ◽  
Theodor Malutan ◽  
Mihai Vata
Keyword(s):  
Palmitic Acid ◽  
Exchange Resin ◽  
Catalyst Particle ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Esterification Reaction ◽  
Macroporous Resin ◽  
Resin Catalyst ◽  
Catalyst Particle Size ◽  
Rate Of Reaction

AbstractThe esterification reaction of palmitic acid with epichlorohydrin catalyzed by an anionic macroporous resin was studied. Purolite A-500 resin proved to be a very effective catalyst in the synthesis of 3-chloro-2-hydroxypropyl palmitate. The effects of certain parameters such as speed of agitation, catalyst particle size, catalyst loading, temperature, initial molar ratio between reactants on the rate of reaction were studied. It was found that the overall rate is intrinsically kinetically controlled. The structure of synthesized ester was confirmed by FTIR and 1H NMR analyses.

Construction of high-efficient visible photoelectrocatalytic system for carbamazepine degradation: Kinetics, degradation pathway and mechanism

2020 ◽  
Vol 31 (10) ◽  
pp. 2661-2667
Author(s):  
Ruonan Guo ◽  
Li-Chao Nengzi ◽  
Ying Chen ◽  
Qingqing Song ◽  
Jianfeng Gou ◽  
...  
Keyword(s):  
Degradation Kinetics ◽  
Degradation Pathway ◽  
High Efficient

Photocatalytic oxidation of methyl ethyl ketone over sol-gel and commercial TiO2 for the improvement of indoor air

2006 ◽  
Vol 53 (11) ◽  
pp. 107-115 ◽  
Author(s):  
C. Raillard ◽  
V. Héquet ◽  
P. Le Cloirec ◽  
J. Legrand
Keyword(s):  
Methyl Ethyl Ketone ◽  
Indoor Air ◽  
Photocatalytic Oxidation ◽  
Degradation Kinetics ◽  
Sol Gel ◽  
Degradation Pathway ◽  
Air Pollutant ◽  
Methyl Ethyl ◽  
Fixed Temperature ◽  
Glass Plates

This work focuses on the photocatalytic oxidation of gaseous methyl ethyl ketone chosen as a typical indoor air pollutant. Two types of TiO2 coatings were prepared and deposited on glass plates: one using the commercial Degussa P25 TiO2 and the other one by sol-gel method. The first objective of this study was to compare different ways of preparing thin films of sol-gel TiO2 coated on glass plates, taking into account their general aspect and their photocatalytic efficiency. Several parameters were tested, such as the stabilising agent, the glass type of the support, the number of coatings and the calcination temperature. One of the synthesised materials was then kept to carry out the following study. The study aimed to assess the influence of TiO2 coating types on the effect of water vapour. This was achieved by performing MEK photocatalytic degradation kinetics under two levels of humidity at a fixed temperature. Experimental results were then modelled by the Langmuir-Hinshelwood equation. The obtained parameters gave specific trends in function of the considered catalyst. The second part of this work was to identify MEK degradation byproducts during its photocatalytic oxidation. The main detected intermediate was acetaldehyde, followed by methyl formate. A MEK degradation pathway was then proposed.

scholarly journals Degradation of clofibric acid in UV/chlorine disinfection process: kinetics, reactive species contribution and pathways

2018 ◽  
Vol 5 (2) ◽  
pp. 171372 ◽  
Author(s):  
Yuqing Tang ◽  
Xueting Shi ◽  
Yongze Liu ◽  
Li Feng ◽  
Liqiu Zhang
Keyword(s):  
Degradation Kinetics ◽  
Clofibric Acid ◽  
Basic Solution ◽  
Uv Photolysis ◽  
Chlorination Process ◽  
Chlorine Disinfection ◽  
First Order Kinetics ◽  
Disinfection Process ◽  
Acidic Conditions ◽  
Degradation Intermediates

As a potential endocrine disruptor, clofibric acid (CA) was investigated in this study for its degradation kinetics and pathways in UV/chlorine process. The results showed that CA in both UV photolysis and UV/chlorine processes could be degraded via pseudo-first-order kinetics, while it almost could not be degraded in the dark chlorination process. The observed rate constant ( k obs ) in UV photolysis was 0.0078 min −1, and increased to 0.0107 min −1 combining with 0.1 mM chlorine. The k obs increased to 0.0447 min −1 with further increasing the chlorine dosage from 0.1 to 1.0 mM, and reached a plateau at higher dosage (greater than 1.0 mM). The higher k obs was obtained at acid solution rather than basic solution. Moreover, the calculated contributions of radical species to k obs indicated that the HO• contributed significantly to CA degradation in acidic conditions, while the reactive chlorine species and UV direct photolysis dominated in neutral and basic solution. The degradation of CA was slightly inhibited in the presence of HC O 3 − (1 ∼ 50 mM), barely affected by the presence of Cl − (1 ∼ 200 mM) and greatly suppressed by humic acid (0 ∼ 5 mg l −1 ). Thirteen main degradation intermediates and three degradation pathways of CA were identified during UV/chlorine process.

scholarly journals Poly(catechol) modified Fe3O4 magnetic nanocomposites with continuous high Fenton activity for organic degradation at neutral pH

2021 ◽  
Author(s):  
Yani Hua ◽  
Chuan Wang ◽  
Sha Wang ◽  
Juan Xiao
Keyword(s):  
Catalytic Activity ◽  
Fenton Reaction ◽  
Organic Molecules ◽  
Precipitation Method ◽  
Organic Degradation ◽  
Redox Pair ◽  
Iron Leaching ◽  
Acidic Conditions ◽  
Ph Range ◽  
Co Precipitation

Abstract Fe3O4 magnetic nanoparticles (MNPs) have been widely used as a recyclable catalyst in Fenton reaction for organic degradation. However, the pristine MNPs suffer from the drawbacks of iron leaching in acidic conditions as well as the decreasing catalytic activity of organic degradation at a pH higher than 3.0. To solve the problems, Fe3O4 MNPs were modified by poly(catechol) (Fe3O4/PCC MNPs) using a facile chemical co-precipitation method. The poly(catechol) modification improved both the dispersity and the surface negative charges of Fe3O4/PCC MNPs, which are beneficial to the catalytic activity of MNPs for organics degradation. Moreover, the poly(catechol) modification enhanced the efficiency of Fe(II) regeneration during Fenton reaction due to the acceleration of Fe(III) reduction by the phenolic/quinonoid redox pair. As a result, the Fenton reaction with Fe3O4/PCC MNPs could efficiently degrade organic molecules, exampled by methylene blue (MB), in an expanded pH range between 3.0 and 10.0. In addition, Fe3O4/PCC MNPs could be reused up to 8 cycles for the MB degradation with negligible iron leaching of lower than 1.5 mg L-1. This study demonstrated Fe3O4/PCC MNPs are a promising heterogeneous Fenton catalysts for organic degradation.

scholarly journals Photo degradation kinetics of insensitive munitions constituents nitroguanidine, nitrotriazolone, and dinitroanisole in natural waters

2021 ◽  
Author(s):  
Lee Moores ◽  
Stacy Jones ◽  
Garrett George ◽  
David Henderson ◽  
Timothy Schutt
Keyword(s):  
Laboratory Experiments ◽  
Natural Waters ◽  
Matrix Effects ◽  
Degradation Kinetics ◽  
Relative Rate ◽  
Ph Dependence ◽  
Degradation Pathway ◽  
Quantum Yields ◽  
The Individual ◽  
Kinetics Of

Herein the matrix effects on the kinetics of aqueous photolysis for the individual munitions constituents of IMX-101: nitroguanidine (NQ), dinitroanisole (DNAN), and nitrotriazolone (NTO) are reported along with the environmentally relevant kinetics and quantum yields. Photolysis potentially represents a major degradation pathway for these munitions in the environment and further understanding the complex matrices effects on photolytic kinetics was needed. Aqueous systems are of particular interest due to the high solubility of NQ (3,800 ppm) and NTO (16,642 ppm) compared to the traditional munitions trinitrotoluene (TNT, 100.5 ppm) and 1,3,5-trinitro-1,3,5-triazine (RDX, 59.9 ppm). Environmental half-lives (and quantum yields) were found to be 0.44 days, 0.83 days, and 4.4 days for NQ, DNAN, and NTO, respectively, under natural sunlight. In laboratory experiments using nominally 300 nm bulbs in a merry-go-round style reactor in DI water the relative rate of photolysis for the three munitions constituents followed the same order NQ > DNAN > NTO, where DNAN and NTO reacted 57 and 115 times more slowly, respectively, than NQ. In the various environmentally relevant matrices tested in the laboratory experiments NQ was not significantly affected, DNAN showed a faster degradation with increasing ionic strength, and NTO showed a modest salinity and pH dependence on its rate of photolysis.

scholarly journals Thermal Stability and Degradation Kinetics of Patulin in Highly Acidic Conditions: Impact of Cysteine

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 662
Author(s):  
Enjie Diao ◽  
Kun Ma ◽  
Hui Zhang ◽  
Peng Xie ◽  
Shiquan Qian ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Degradation Kinetics ◽  
Correlation Coefficients ◽  
Degradation Process ◽  
Weibull Model ◽  
Degradation Efficiency ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Acidic Conditions ◽  
Kinetics Of

The thermal stability and degradation kinetics of patulin (PAT, 10 μmol/L) in pH 3.5 of phosphoric-citric acid buffer solutions in the absence and presence of cysteine (CYS, 30 μmol/L) were investigated at temperatures ranging from 90 to 150 °C. The zero-, first-, and second-order models and the Weibull model were used to fit the degradation process of patulin. Both the first-order kinetic model and Weibull model better described the degradation of patulin in the presence of cysteine while it was complexed to simulate them in the absence of cysteine with various models at different temperatures based on the correlation coefficients (R2 > 0.90). At the same reaction time, cysteine and temperature significantly affected the degradation efficiency of patulin in highly acidic conditions (p < 0.01). The rate constants (kT) for patulin degradation with cysteine (0.0036–0.3200 μg/L·min) were far more than those of treatments without cysteine (0.0012–0.1614 μg/L·min), and the activation energy (Ea = 43.89 kJ/mol) was far less than that of treatment without cysteine (61.74 kJ/mol). Increasing temperature could obviously improve the degradation efficiency of patulin, regardless of the presence of cysteine. Thus, both cysteine and high temperature decreased the stability of patulin in highly acidic conditions and improved its degradation efficiency, which could be applied to guide the detoxification of patulin by cysteine in the juice processing industry.

scholarly journals Removal of Sulfamethoxazole, Sulfathiazole and Sulfamethazine in their Mixed Solution by UV/H2O2 Process

2019 ◽  
Vol 16 (10) ◽  
pp. 1797 ◽  
Author(s):  
Guangcan Zhu ◽  
Qi Sun ◽  
Chuya Wang ◽  
Zhonglian Yang ◽  
Qi Xue
Keyword(s):  
Uv Light ◽  
Degradation Pathway ◽  
Photochemical Oxidation ◽  
Order Kinetic ◽  
Mixed Solution ◽  
Initial Concentration ◽  
Aqueous Environments ◽  
Initial Ph ◽  
Order Kinetic Model ◽  
Acidic Conditions

Sulfamethoxazole (SMZ), sulfathiazole (STZ) and sulfamethazine (SMT) are typical sulfonamides, which are widespread in aqueous environments and have aroused great concern in recent years. In this study, the photochemical oxidation of SMZ, STZ and SMT in their mixed solution using UV/H2O2 process was innovatively investigated. The result showed that the sulfonamides could be completely decomposed in the UV/H2O2 system, and each contaminant in the co-existence system fitted the pseudo-first-order kinetic model. The removal of sulfonamides was influenced by the initial concentration of the mixed solution, the intensity of UV light irradiation, the dosage of H2O2 and the initial pH of the solution. The increase of UV light intensity and H2O2 dosage substantially enhanced the decomposition efficiency, while a higher initial concentration of mixed solution heavily suppressed the decomposition rate. The decomposition of SMZ and SMT during the UV/H2O2 process was favorable under neutral and acidic conditions. Moreover, the generated intermediates of SMZ, STZ and SMT during the UV/H2O2 process were identified in depth, and a corresponding degradation pathway was proposed.

scholarly journals pH-Dependent Degradation of Diclofenac by a Tunnel-Structured Manganese Oxide

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2203
Author(s):  
Ching-Yao Hu ◽  
Yu-Jung Liu ◽  
Wen-Hui Kuan
Keyword(s):  
Formation Control ◽  
High Performance ◽  
Degradation Kinetics ◽  
Removal Rate ◽  
Solution Ph ◽  
Mn Oxide ◽  
Highly Active ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Key Parameter

The mechanism of diclofenac (DIC) degradation by tunnel-structured γ-MnO2, with superior oxidative and catalytic abilities, was determined in terms of solution pH. High-performance liquid chromatography with mass spectroscopy (HPLC–MS) was used to identify intermediates and final products of DIC degradation. DIC can be efficiently oxidized by γ-MnO2 in an acidic medium, and the removal rate decreased significantly under neutral and alkaline conditions. The developed model can successfully fit DIC degradation kinetics and demonstrates electron transfer control under acidic conditions and precursor complex formation control mechanism under neutral to alkaline conditions, in which the pH extent for two mechanisms exactly corresponds to the distribution percentage of ionized species of DIC. We also found surface reactive sites (Srxn), a key parameter in the kinetic model for mechanism determination, to be exactly a function of solution pH and MnO2 dosage. The main products of oxidation with a highly active hydroxylation pathway on the tunnel-structured Mn-oxide are 5-iminoquinone DIC, hydroxyl-DIC, and 2,6-dichloro-N-o-tolylbenzenamine.

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