Photodegradation of amoxicillin in aqueous solution under simulated irradiation: influencing factors and mechanisms

2013 ◽  
Vol 67 (7) ◽  
pp. 1605-1611 ◽  
Author(s):  
Qian Zhao ◽  
Li Feng ◽  
Xiang Cheng ◽  
Chao Chen ◽  
Liqiu Zhang
Keyword(s):  
Aqueous Solution ◽  
Singlet Oxygen ◽  
Natural Waters ◽  
Pure Water ◽  
Chemical Species ◽  
Xenon Lamp ◽  
First Order ◽  
First Order Kinetics ◽  
Photodegradation Rate ◽  
Pseudo First Order

This paper investigated the effects of selected common chemical species in natural waters (HCO3−, NO3− and humic acids (HA)) on the photodegradation of amoxicillin (AMO) under simulated irradiation using a 300 W xenon lamp. Quenching experiments were carried out to explore the mechanisms of AMO photodegradation. The results indicated that AMO photodegradation followed pseudo-first-order kinetics. Increasing AMO concentration from 100 to 1,000 μg L−1 led to the decrease in the photodegradation rate constant from 0.2411 to 0.1912 min−1. The presence of NO3− and HA obviously inhibited the photodegradation rate of AMO because they can compete for photons with AMO. Bicarbonate, as a hydroxyl radical (·OH) scavenger, also adversely affected AMO photodegradation. Quenching experiments in pure water suggested that AMO could undergo self-sensitized photooxidation via ·OH and singlet oxygen (1O2), accounting for AMO removal of 34.86 and 8.26%, respectively. In HA solutions, the indirect photodegradation of AMO was mostly attributed to the produced ·OH (22.37%), 1O2 (24.12%) and 3HA* (20.80%), whereas the contribution of direct photodegradation was to some extent decreased.

scholarly journals Efficient degradation of naproxen by persulfate activated with zero-valent iron: performance, kinetic and degradation pathways

2020 ◽  
Vol 81 (10) ◽  
pp. 2078-2091
Author(s):  
Shuyu Dong ◽  
Xiaoxue Zhai ◽  
Ruobing Pi ◽  
Jinbao Wei ◽  
Yunpeng Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydroxyl Radical ◽  
Rate Constants ◽  
Zero Valent Iron ◽  
Degradation Pathways ◽  
First Order ◽  
First Order Kinetics ◽  
Degradation Rates ◽  
Initial Ph ◽  
Pseudo First Order

Abstract Degradation of naproxen (NAP) by persulfate (PS) activated with zero-valent iron (ZVI) was investigated in our study. The NAP in aqueous solution was degraded effectively by the ZVI/PS system and the degradation exhibited a pseudo-first-order kinetics pattern. Both sulfate radical (SO4•−) and hydroxyl radical (HO•) participate in the NAP degradation. The second-order rate constants for NAP reacting with SO4•− and HO• were (5.64 ± 0.73) × 109 M−1 s−1 and (9.05 ± 0.51) × 109 M−1 s−1, respectively. Influence of key parameters (initial pH, PS dosage, ZVI dosage, and NAP dosage) on NAP degradation were evaluated systematically. Based on the detected intermediates, the pathways of NAP degradation in ZVI/PS system was proposed. It was found that the presence of ammonia accelerated the corrosion of ZVI and thus promoted the release of Fe2+, which induced the increased generation of sulfate radicals from PS and promoted the degradation of NAP. Compared to its counterpart without ammonia, the degradation rates of NAP by ZVI/PS were increased to 3.6–17.5 folds and 1.2–2.2 folds under pH 7 and pH 9, respectively.

scholarly journals Photodegradation of lincomycin in aqueous solution

2006 ◽  
Vol 2006 ◽  
pp. 1-6 ◽  
Author(s):  
Agatino Di Paola ◽  
Maurizio Addamo ◽  
Vincenzo Augugliaro ◽  
Elisa García-López ◽  
Vittorio Loddo ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Uv Light ◽  
Heterogeneous Systems ◽  
Degradation Pathways ◽  
Direct Photolysis ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order ◽  
Complete Mineralization

Aqueous solutions of lincomycin were irradiated with UV light in homogeneous and heterogeneous systems. Lincomycin disappeared in both systems but the presence ofTiO2noticeably accelerated the degradation of the antibiotic in comparison with direct photolysis. The rate of decomposition was dependent on the concentration of lincomycin and followed a pseudo-first-order kinetics. Photolysis involved only the oxidation of lincomycin without mineralization. Differently, the treatment withTiO2and UV light resulted in a complete mineralization of the antibiotic. The degradation pathways involved S- and N-demethylation and propyldealkylation. The mineralization of the molecule led to the formation of sulfate, ammonium, and nitrate ions.

Kinetics of tartrazine photodegradation by UV/H2O2 in aqueous solution

2014 ◽  
Vol 68 (1) ◽  
Author(s):  
Petruta Oancea ◽  
Viorica Meltzer
Keyword(s):  
H2o2 Concentration ◽  
Reaction Intermediates ◽  
Original Design ◽  
Experimental Conditions ◽  
First Order ◽  
Toc Removal ◽  
First Order Kinetics ◽  
Photodegradation Rate ◽  
Pseudo First Order ◽  
Kinetics Of

AbstractIn the present work, kinetics of tartrazine decay by UV irradiation and H2O2 photolysis, and the removal of total organic carbon (TOC) under specific experimental conditions was explored. Irradiation experiments were carried out using a photoreactor of original design with a low-pressure Hg vapour lamp. The photodegradation rate of tartrazine was optimised with respect to the H2O2 concentration and temperature for the constant dye concentration of 1.035 × 10−5 M. Tartrazine degradation and the removal of TOC followed the pseudo-first-order kinetics. The much higher k obs value for tartrazine degradation (7.91 × 10−4 s−1) as compared with the TOC removal (2.3 × 10−4 s−1) confirmed the presence of reaction intermediates in the solution.

Dicamba Degradation Using O3/UV Process in Aqueous Solution

2014 ◽  
Vol 941-944 ◽  
pp. 1124-1127
Author(s):  
Lan Chen
Keyword(s):  
Aqueous Solution ◽  
Promoting Effect ◽  
First Order ◽  
Pesticide Pollution ◽  
Inhibiting Effect ◽  
Bicarbonate Ions ◽  
First Order Kinetics ◽  
Reaction Solution ◽  
Impurity Ions ◽  
Pseudo First Order

In order to control pesticide pollution, the degradation of dicamba in aqueous solution was investigated in a bubble reactor in laboratory using separate UV, separate O3, O3/UV systems. The experimental results show that UV has a synergistic effect on ozonation. The synergy factor of O3/UV system is calculated to be 1.96. The degradation of dicamba follows pseudo-first-order kinetics. Considering that the composition of actual water is complex, chloride, nitrate, carbonate and bicarbonate ions, common ions appeared in actual water, were selected to add to reaction solution in O3/UV system. Chloride and nitrite ions have inhibiting effect. Carbonate and bicarbonate ions have promoting effect. In O3/UV system, different impurity ions have different influence on dicamba degradation with small amount addition.

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.

Photodegradation of sulfonamide antimicrobial compounds (sulfadiazine, sulfamethizole, sulfamethoxazole and sulfathiazole) in various UV/oxidant systems

2015 ◽  
Vol 71 (3) ◽  
pp. 412-417 ◽  
Author(s):  
J. T. Wu ◽  
C. H. Wu ◽  
C. Y. Liu ◽  
W. J. Huang
Keyword(s):  
Degradation Rate ◽  
Removal Rate ◽  
Antimicrobial Compounds ◽  
Mineralization Rate ◽  
First Order ◽  
First Order Kinetics ◽  
Photodegradation Rate ◽  
Total Organic Carbon Removal ◽  
Pseudo First Order ◽  
H2o2 System

This study used Na2S2O8, NaBrO8 and H2O2 to degrade sulfadiazine (SDZ), sulfamethizole (SFZ), sulfamethoxazole (SMX) and sulfathiazole (STZ) under ultraviolet (UV) irradiation. The initial concentration of sulfonamide and oxidant in all experiments was 20 mg/L and 5 mM, respectively. The degradation rate for sulfonamides satisfies pseudo-first-order kinetics in all UV/oxidant systems. The highest degradation rate for SDZ, SFZ, SMX and STZ was in the UV/Na2S2O8, UV/NaBrO3, UV/Na2S2O8 and UV/H2O2 system, respectively. In the UV/Na2S2O8 system, the photodegradation rate of SDZ, SFZ, SMX and STZ was 0.0245 min−1, 0.0096 min−1, 0.0283 min−1 and 0.0141 min−1, respectively; moreover, for the total organic carbon removal rate for SDZ, SFZ, SMX and STZ it was 0.0057 min−1, 0.0081 min−1, 0.0130 min−1 and 0.0106 min−1, respectively. Experimental results indicate that the ability of oxidants to degrade sulfonamide varied with pollutant type. Moreover, UV/Na2S2O8 had the highest mineralization rate for all tested sulfonamides.

The effect of photosensitizer on diclofenac photodegradation under simulated sunlight

2013 ◽  
Vol 67 (2) ◽  
pp. 418-423 ◽  
Author(s):  
N. Zhang ◽  
G. G. Liu ◽  
H. J. Liu ◽  
Y. L. Wang ◽  
T. Li
Keyword(s):  
High Performance ◽  
Degradation Products ◽  
Degradation Pathways ◽  
Simulated Sunlight ◽  
Liquid Chromatography Mass Spectrometry ◽  
First Order ◽  
Chemical Structures ◽  
First Order Kinetics ◽  
Photodegradation Rate ◽  
Pseudo First Order

This paper studies the effect of photosensitizer (acetone, H2O2, surfactant and pigment) on photodegradation of diclofenac (DCF) under simulated sunlight. The results demonstrate that degradation pathways proceed via pseudo first-order kinetics in all cases. The photodegradation rate was found to increase with increasing acetone and H2O2. Surfactant and pigment inhibited the photodegradation of DCF. Finally, four kinds of main degradation products were observed by high performance liquid chromatography/mass spectrometry and their chemical structures were suggested.

scholarly journals Kinetic Study on Removal of Sulphur Mustard on Granular Activated Carbon from Aqueous Solution

2016 ◽  
Vol 1 (2) ◽  
pp. 167 ◽  
Author(s):  
Anuradha Baghel ◽  
Beer Singh
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Rate Constant ◽  
Half Life ◽  
Chemical Warfare Agent ◽  
Sulphur Mustard ◽  
Adsorptive Removal ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order

Sulphur mustard is a powerful blister agent and has been worked as a chemical warfare agent. No specific antidote is available for its wound. Therefore, adsorptive removal is an effective way of removal. Here, adsorptive removal of sulphur mustard from aqueous solution was studied on activated carbon and screened out MeOH : H2O (1 : 1) solution as a good solvent than others used solvent. Adsorption isotherm of sulphur mustard was compared with its hydrolysis in the same solution. Kinetics of sulphur mustard removal on carbon from aqueous solution was found to be slower than hydrolysis and follow pseudo first order kinetics with the rate constant 5.04 X 10–3 min-1 and half life 137.5 min. The hydrolysis of sulphur mustard in MeOH : H2O (1 : 1) solution was found to be following the pseudo first order kinetics with the rate constant 8.68 x10-3 min-1 and half life 79.8 min.

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.

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.

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