scholarly journals Biodegradation of Polyethoxylated Nonylphenols

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Yassellis Ruiz ◽  
Luis Medina ◽  
Margarita Borusiak ◽  
Nairalith Ramos ◽  
Gilberto Pinto ◽  
...  
Keyword(s):  
Degradation Products ◽  
Life Time ◽  
Viscosity Data ◽  
Natural Environments ◽  
Maximal Growth ◽  
Bacterial Strains ◽  
Kinetic Rate Constant ◽  
Kinetic Rate ◽  
First Order ◽  
First Order Kinetics

Polyethoxylated nonylphenols, with different ethoxylation degrees (), are incorporated into many commercial and industrial products such as detergents, domestic disinfectants, emulsifiers, cosmetics, and pesticides. However, the toxic effects exerted by their degradation products, which are persistent in natural environments, have been demonstrated in several animal and invertebrate aquatic species. Therefore, it seems appropriate to look for indigenous bacteria capable of degrading native and its derivatives. In this paper, the isolation of five bacterial strains, capable of using , as unique carbon source, is described. The most efficient degrader bacterial strains were identified as Pseudomonas fluorescens (strain Yas2) and Klebsiella pneumoniae (strain Yas1). Maximal growth rates were reached at pH 8, 27°C in a 5% medium. The degradation extension, followed by viscometry assays, reached 65% after 54.5 h and 134 h incubation times, while the COD values decreased by 95% and 85% after 24 h for the Yas1 and Yas2 systems, respectively. The BOD was reduced by 99% and 99.9% levels in 24 h and 48 h incubations. The viscosity data indicated that the biodegradation by Yas2 follows first-order kinetics. Kinetic rate constant () and half life time () for this biotransformation were estimated to be 0.0072 h−1 and 96.3 h, respectively.

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.

scholarly journals A multivariate study of the rGO/g-C3N4 composite for the photocatalytic degradation of bisphenol A: Characterization, degradation kinetics, products identification, and ecotoxicity

2021 ◽  
Author(s):  
Chubraider Xavier ◽  
Bianca Rebelo Lopes ◽  
Caue Ribeiro ◽  
Eduardo Bessa Azevedo
Keyword(s):  
Bisphenol A ◽  
Degradation Products ◽  
Degradation Kinetics ◽  
Surface Response Methodology ◽  
First Order ◽  
Surface Areas ◽  
First Order Kinetics ◽  
Reduced Graphene ◽  
Endocrine Disrupting ◽  
Oxidation Agent

Abstract Bisphenol A (BPA), a common polymer plasticizer, is a contaminant of emerging concern with endocrine disrupting activity. Among existing abatement methods, photodegradation demands easily fabricated, inexpensive, high photoactive catalysts, leading to non-toxic byproducts after degradation. It is proposed an optimized (surface response methodology) catalyst for those goals: graphitic carbon nitride impregnated with reduced graphene oxide. The method was based on the sonication of preformed particles followed by reduction with hydrazine in reflux, a methodology that allows for better reproducibility and larger specific surface areas. The catalyst removed 90% of BPA (100 mL, 100 µg L− 1) in 90 min under UV irradiation (365 nm, 26 W) compared to 50% with pure g-C3N4 (pseudo-first-order kinetics). Tests with radicals scavengers revealed that superoxide radical was the main oxidation agent in the system. By mass spectrometry, two major degradation products were identified, which were less ecotoxic than BPA towards a series of organisms, according to in silico estimations performed with the ECOSAR 2.0 software.

scholarly journals ESTUDO DE ESTABILIDADE DO FOSFATO DISSÓDICO DE PREDNISOLONA EM CONDIÇÕES DE ESTRESSE OXIDATIVO E TÉRMICO, EM FORMULAÇÃO ORAL

2018 ◽  
Vol 35 (4) ◽  
pp. 09
Author(s):  
Cleber Antonio Lindino ◽  
Marcia Lina Mitsui ◽  
Rodolfo Ortiguara ◽  
Daiane Felin ◽  
Mauricio Ferreira Da Rosa ◽  
...  
Keyword(s):  
High Performance ◽  
Dosage Form ◽  
Degradation Products ◽  
Degradation Process ◽  
Oral Solution ◽  
Form Solution ◽  
Oral Dosage ◽  
First Order ◽  
First Order Kinetics

This work was to investigate the process of degradation of the drug Prednisolone Sodium Phosphate (FSP) in oral solution dosage form through the degradation experiments, evaluating the parameters in accordance with Resolution 899/2003 ANVISA and the degradation process of the drug. The method by high performance liquid chromatography (HPLC) developed for the determination of the drug was validated to demonstrate its applicability as an indicator of stability, ensuring reliability. After the method be validated to study the degradation of the drug, it was shown that drastic conditions of oxidative stress (H O 30%) and 2 2 temperature 60°C, the degradation of the drug is dependent on its concentration (first order kinetics). The results were  satisfactory, showing that this method is suitable to investigate the formation of degradation products in oral dosage form solution

scholarly journals Determination of Chemical Stability of Two Oral Antidiabetics, Metformin and Repaglinide in the Solid State and Solutions Using LC-UV, LC-MS, and FT-IR Methods

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4430
Author(s):  
Anna Gumieniczek ◽  
Anna Berecka-Rycerz ◽  
Tomasz Mroczek ◽  
Krzysztof Wojtanowski
Keyword(s):  
High Temperature ◽  
Degradation Products ◽  
Degradation Kinetics ◽  
Magnesium Stearate ◽  
Oral Antidiabetics ◽  
First Order ◽  
First Order Kinetics ◽  
Ft Ir ◽  
The Stability

Firstly, metformin and repaglinide were degraded under high temperature/humidity, UV/VIS light, in different pH and oxidative conditions. Secondly, a new validated LC-UV method was examined, as to whether it validly determined these drugs in the presence of their degradation products and whether it is suitable for estimating degradation kinetics. Finally, the respective LC-MS method was used to identify the degradation products. In addition, using FT-IR method, the stability of metformin and repaglinide was scrutinized in the presence of polyvinylpyrrolidone (PVP), mannitol, magnesium stearate, and lactose. Significant degradation of metformin, following the first order kinetics, was observed in alkaline medium. In the case of repaglinide, the most significant and quickest degradation, following the first order kinetics, was observed in acidic and oxidative media (0.1 M HCl and 3% H2O2). Two new degradation products of metformin and nine new degradation products of repaglinide were detected and identified when the stressed samples were examined by our LC-MS method. What is more, the presence of PVP, mannitol, and magnesium stearate proved to affect the stability of metformin, while repaglinide stability was affected in the presence of PVP and magnesium stearate.

scholarly journals Hydrolysis and Photolysis Kinetics, and Identification of Degradation Products of the Novel Bactericide 2-(4-Fluorobenzyl)-5-(Methylsulfonyl)-1,3,4-Oxadiazole in Water

2018 ◽  
Vol 15 (12) ◽  
pp. 2741 ◽  
Author(s):  
Xingang Meng ◽  
Lingzhu Chen ◽  
Yuping Zhang ◽  
Deyu Hu ◽  
Baoan Song
Keyword(s):  
Degradation Product ◽  
High Performance ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
The Novel ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
High Resolution Mass Spectrometer

Hydrolysis and photolysis kinetics of Fubianezuofeng (FBEZF) in water were investigated in detail. The hydrolysis half-lives of FBEZF depending on pH, initial concentration, and temperature were (14.44 d at pH = 5; 1.60 d at pH = 7), (36.48 h at 1.0 mg L−1; 38.51 h at 5.0 mg L−1; and 31.51 h at 10.0 mg L−1), and (77.02 h at 15 °C; 38.51 h at 25 °C; 19.80 h at 35 °C; and 3.00 h at 45 °C), respectively. The photolysis half-life of FBEZF in different initial concentrations were 8.77 h at 1.0 mg L−1, 8.35 h at 5.0 mg L−1, and 8.66 h at 10.0 mg L−1, respectively. Results indicated that the degradation of FBEZF followed first-order kinetics, as the initial concentration of FBEZF only had a slight effect on the UV irradiation effects, and the increase in pH and temperature can substantially accelerate the degradation. The hydrolysis Ea of FBEZF was 49.90 kJ mol−1, which indicates that FBEZF belongs to medium hydrolysis. In addition, the degradation products were identified using ultra-high-performance liquid chromatography coupled with an Orbitrap high-resolution mass spectrometer. One degradation product was extracted and further analyzed by 1H-NMR, 13C-NMR, 19F-NMR, and MS. The degradation product was identified as 2-(4-fluorobenazyl)-5-methoxy-1,3,4-oxadiazole, therefore a degradation mechanism of FBEZF in water was proposed. The research on FBEZF can be helpful for its safety assessment and increase the understanding of FBEZF in water environments.

Biodegradation of Bisphenol-A in aerobic membrane bioreactor sludge

2013 ◽  
Vol 68 (9) ◽  
pp. 1926-1931 ◽  
Author(s):  
Brahima Seyhi ◽  
Patrick Drogui ◽  
Gerardo Buelna ◽  
Jean François Blais
Keyword(s):  
Bisphenol A ◽  
Chemical Oxygen Demand ◽  
Rate Constant ◽  
Membrane Bioreactor ◽  
Oxygen Demand ◽  
Degradation Process ◽  
Order Kinetic ◽  
Kinetic Rate Constant ◽  
Kinetic Rate ◽  
First Order

Bisphenol-A (BPA) biodegradation was studied in a membrane bioreactor under aerobic conditions. The effects of the initial BPA concentration and initial chemical oxygen demand (COD) concentration on BPA biodegradation were investigated. The degradation process followed a first-order kinetic (more than 98% of BPA was removed) with a kinetic rate constant of 1.134 h−1 using an initial BPA concentration of 1.0 mg L−1. The kinetic rate constant decreased to 0.611 h−1 when the initial BPA concentration increased to 5.0 mg L−1. The initial COD concentration (400 and 2,000 mg L−1) did not affect the biodegradation kinetic of BPA.

Photocatalytic Degradation of 4-Chlorophenol with a Novel α-Ga2O3

2011 ◽  
Vol 356-360 ◽  
pp. 1319-1322
Author(s):  
Bao Xiu Zhao ◽  
Li Na Zheng ◽  
Yuan Wei ◽  
Fan Yang
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Degradation ◽  
Degradation Kinetics ◽  
Endocrine Disrupting Chemicals ◽  
Life Time ◽  
First Order ◽  
First Order Kinetics ◽  
Endocrine Disrupting ◽  
The Common ◽  
Main Factors

Chlorophenols is a kind of environmental endocrine disrupting chemicals (EDCs) and it is hard for the common methods to degrade or remove them, so how to decompose these pollutants has attracted researches’ attention. In this paper, a novel α-Ga2O3was used to degrade 4-chlorophenol via photocatalytic reaction and degradation kinetics was investigated. The effects of main factors, such as dosage of α-Ga2O3and pH of aqueous solution, on degradation were studied, and degradation kinetics was also established. Experimental results displayed that the optimal pH of aqueous solution was about 7.8 and almost 98% 4-chlorophenol was decomposed after 2 h, when the dosage of α-Ga2O3was 0.4 g and the initial concentration of 4-chlorophenol was 20 mg/L (V=200 ml). Photocatalytic degradation of 4-chlorophenol with α-Ga2O3abided by first-order kinetics and half-life time was 20.4 min.

scholarly journals Photodegradation of diclofenac in aqueous solution by simulated sunlight irradiation: kinetics, thermodynamics and pathways

2017 ◽  
Vol 75 (9) ◽  
pp. 2163-2170 ◽  
Author(s):  
N. Zhang ◽  
J. M. Li ◽  
G. G. Liu ◽  
X. L. Chen ◽  
K. Jiang
Keyword(s):  
High Performance ◽  
Degradation Products ◽  
Photobacterium Phosphoreum ◽  
Degradation Pathways ◽  
Simulated Sunlight ◽  
Liquid Chromatography Mass Spectrometry ◽  
Sunlight Irradiation ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order

Diclofenac (DCF) is one of the most frequently detected pharmaceuticals in various water samples. This paper studied the effects of aquatic environmental factors (pH, temperature and dissolved organic matter) on photodegradation of DCF under simulated sunlight. The results demonstrate that degradation pathways proceed via pseudo first-order kinetics in all cases and the photodegradation of DCF by simulated sunlight. Thermodynamic study indicated that the photodegradation course is spontaneous, exothermic and irreversible. The rate constant gradually increased when the pH increased from 3 to 5, then decreased when the pH increased from 5 to 8, and finally increased when the pH further increased from 8 to 12. Humic acid inhibited the photodegradation of DCF. Three kinds of main degradation products were observed by high performance liquid chromatography/mass spectrometry and the degradation pathways were suggested. A toxicity test using Photobacterium phosphoreum T3 Sp indicated the generation of some more toxic products than DCF.

Decolourization of Alizarin Red by Persulfate

2012 ◽  
Vol 610-613 ◽  
pp. 300-305
Author(s):  
Shen Xin Li ◽  
Wei Hu ◽  
Cheng Duan Wang
Keyword(s):  
Ionic Strength ◽  
Uv Irradiation ◽  
Degradation Products ◽  
Kinetics Model ◽  
Dye Wastewater ◽  
Alizarin Red ◽  
First Order ◽  
First Order Kinetics ◽  
Pseudo First Order

The decolourization of dye wastewater by persulfate was studied using alizarin red as a model dye wastewater. Effects of several parameters, such as dose of oxidant, ionic strength, pH, temperature and UV irradiation, were investigated in detail. The results showed that the decolourization reaction of alizarin red by persulfate could be fitted to a pseudo-first order kinetics model. In addition, no degradation products were observed during the decolourization of alizarin red by persulfate. The results are useful for the treatment of dye wastewater.

scholarly journals A study of photodegradation of quetiapine by the use of LC-MS/MS method

2012 ◽  
Vol 10 (1) ◽  
pp. 232-240 ◽  
Author(s):  
Robert Skibiński
Keyword(s):  
Degradation Products ◽  
High Accuracy ◽  
Reversed Phase ◽  
Structural Elucidation ◽  
Methanol Solution ◽  
First Order ◽  
Photodegradation Product ◽  
First Order Kinetics ◽  
Photodegradation Products

AbstractPhotodegradation of quetiapine under UVC irradiation in methanol solution was investigated and structural elucidation of its photodegradation products was performed with the use of the reversed phase UHPLC system coupled with accurate mass hybrid ESI-Q-TOF mass spectrometer. During one run all essential data for the determination of photodegradation kinetics and for the structural elucidation of the products was collected with the use of auto MS/MS mode. Five degradation products were found and their masses and formulas were obtained with high accuracy (0.26–5.02 ppm). For all the analyzed compounds, MS/MS fragmentation spectra were also obtained allowing structural elucidation of the unknown degradation products and indicating photodegradation pathways of quetiapine. The main photodegradation product was identified as 2-[2-[4-(5-oxidodibenzo[b,f][1,4]thiazepin-11-yl)-1-piperazinyl]ethoxy]-ethanol and the photodegradation reaction yields the first-order kinetics with the rate constant k = 0.1094 h−1.

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