From UV spectra to degradability of industrial wastewater/definition and use of a “shape factor”

The measurement of global parameters such as TOC or specific compounds as phenol is not sufficient for the characterization of high loaded industrial wastewater. A previous study dealing with a treatability test based on the use of a photochemical reactor and the UV spectrophotometric control of the experiment has shown the interest of this alternative procedure for the biodegradability estimation of samples. Starting from a simple typology of wastewater based on the structure of UV spectra, a factor called “Shape Factor”, or SF, ratio of second derivative value at a maximal wavelength on the corresponding peak absorbance, is proposed for the characterization of UV spectra shape. The interest of the use of SF, related to the probable presence of a major absorbing pollutant, is shown after a short kinetic study of the photochemical test for chemical and petrochemical wastewater. The degradation rate constant of the pseudo first order photo-reaction (calculated for the degradation of a major pollutant) seems to be linked to the SF factor. For samples characterized by UV absorption peak(s) and thus a high SF value, the degradation rate constant is relatively important. For example, for effluents the UV spectra of which are very structured, the degradation rate constant is above 2.3 s-1. In conclusion, this simple procedure based on the UV spectroscopic typology of samples must be, on one hand, validated from several industrial effluents, and, on the other hand, improved with a more complete kinetic study.

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Sensitivity analysis using a diffuse pollution hydrologic model to assess factors affecting pesticide concentrations in river water

Water Science & Technology ◽

10.2166/wst.2010.540 ◽

2010 ◽

Vol 62 (11) ◽

pp. 2579-2589 ◽

Cited By ~ 3

Author(s):

Koji Tani ◽

Yoshihiko Matsui ◽

Kentaro Narita ◽

Koichi Ohno ◽

Taku Matsushita

Keyword(s):

Sensitivity Analysis ◽

River Water ◽

Rate Constant ◽

Degradation Rate ◽

Hydrologic Model ◽

Adsorption Coefficient ◽

Pesticide Concentration ◽

Artificial Drainage ◽

Degradation Rate Constant ◽

Intermittent Irrigation

We quantitatively evaluated the factors that affect the concentrations of rice-farming pesticides (an herbicide and a fungicide) in river water by a sensitivity analysis using a diffuse pollution hydrologic model. Pesticide degradation and adsorption in paddy soil affected concentrations of the herbicide pretilachlor but did not affect concentrations of the fungicide isoprothiolane. We attributed this difference to the timing of pesticide application in relation to irrigation and drainage of the rice paddy fields. The herbicide was applied more than a month before water drainage of the fields and runoff was gradual over a long period of time, whereas the fungicide was applied shortly before drainage and runoff was rapid. However, the effects of degradability-in-water on the herbicide and fungicide concentrations were similar, with concentrations decreasing only when the rate constant of degradation in water was large. We also evaluated the effects of intermittent irrigation methods (irrigation/artificial drainage or irrigation/percolation) on pesticide concentrations in river water. The runoff of the fungicide, which is applied near or in the period of intermittent irrigation, notably decreased when the method of irrigation/artificial drainage was changed to irrigation/percolation. In a sensitivity analysis evaluating the synergy effect of degradation and adsorbability in soil, the degradation rate constant in soil greatly affected pesticide concentration when the adsorption coefficient was small but did not affect pesticide concentration when the adsorption coefficient was large. The pesticide concentration in the river water substantially decreased when either or both the degradation rate constant in soil and adsorption coefficient was large.

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pH effect on stability and kinetics degradation of nitazoxanide in solution

Drug Analytical Research ◽

10.22456/2527-2616.101465 ◽

2020 ◽

Vol 4 (1) ◽

pp. 12-17

Author(s):

Fábio Barbosa ◽

Leonardo Pezzi ◽

Julia Sorrentino ◽

Martin Steppe ◽

Nadia Volpato ◽

...

Keyword(s):

Rate Constant ◽

Degradation Product ◽

Degradation Rate ◽

Degradation Kinetics ◽

Ph Effect ◽

Degradation Rate Constant ◽

Main Degradation Product ◽

Wide Ph Range ◽

The Stability ◽

Ph Range

Stability studies correspond to a set of tests designed to assess changes in the quality of a given drug over time and under the influence of a number of factors. Among these factors, pH plays an important role, due to the catalytic effect that hydronium and hydroxide ions can play in several reactions. In the present study, the degradation kinetics of nitazoxanide was evaluated over a wide pH range, and the main degradation product generated was identified by LC-MS/MS. Nitazoxanide showed first-order degradation kinetics in the pH range of 0.01 to 10.0 showing greater stability between pH 1.0 and 4.0. The degradation rate constant calculated for these pH was 0.0885 x 10-2 min-1 and 0.0689 x 10-2 min-1, respectively. The highest degradation rate constant value was observed at pH 10.0 (0.7418 x 10-2 min-1) followed by pH 0.01 (0.5882 x 10-2 min-1). A major degradation product (DP-1) was observed in all conditions tested. Through LC-MS/MS analysis, DP-1 was identified as a product of nitazoxanide deacetylation. The effect of pH on the stability of nitazoxanide and the kinetic data obtained contribute to a better understanding of the intrinsic stability characteristics of nitazoxanide.

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Modified graphene quantum dots-zinc oxide nanocomposites for photocatalytic degradation of organic dyes and commercial herbicide

Journal of Reinforced Plastics and Composites ◽

10.1177/0731684419891245 ◽

2019 ◽

Vol 39 (3-4) ◽

pp. 81-94 ◽

Cited By ~ 1

Author(s):

Suchada Phophayu ◽

Pichitchai Pimpang ◽

Sawitree Wongrerkdee ◽

Supphadate Sujinnapram ◽

Sutthipoj Wongrerkdee

Keyword(s):

Quantum Dots ◽

Photocatalytic Degradation ◽

Rate Constant ◽

Degradation Rate ◽

Carrier Lifetime ◽

Organic Dyes ◽

Graphene Quantum Dots ◽

High Crystallinity ◽

Degradation Rate Constant ◽

Photocatalytic Material

The high crystallinity of graphene quantum dots-ZnO nanocomposites is considered to have a significant effect in improving the carrier lifetime for enhanced photocatalytic degradation. The graphene quantum dots-ZnO nanocomposites were synthesized by adding graphene quantum dots solution into starting precursors during the precipitation. Characterization was performed using various techniques. High crystallinity of graphene quantum dots-ZnO nanocomposites is obtained in terms of increased crystal size and decreased dislocation density. The improved crystallinity increases the carrier lifetime on the material surface for the functional improvement of photocatalytic material. Photocatalytic test of methylene blue and methyl orange was performed under UV irradiation. Degradation rate constant reaches the maximum value for both organic dyes for the appropriate preparing condition of graphene quantum dots-ZnO nanocomposites. The graphene quantum dots-ZnO nanocomposites were then applied to degrade commercial glyphosate herbicide contaminants for an agricultural wastewater treatment investigation. The investigation aims to demonstrate a facile useful way of herbicide contaminant reduction for the better health of farmers. The graphene quantum dots-ZnO nanocomposites show an enhancement of the photocatalytic process with improved degradation rate constant (23% increased) in comparison to pure ZnO. Therefore, this work demonstrates that graphene quantum dots-ZnO nanocomposites can be used as a photocatalytic material for degrading organic dyes and commercial herbicide contaminants owing to its low-cost and environmental-friendly properties.

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Intensification of a Pond System by Fibrous Carriers

Water Science & Technology ◽

10.2166/wst.1993.0151 ◽

1993 ◽

Vol 28 (7) ◽

pp. 117-123 ◽

Cited By ~ 3

Author(s):

Qi Peishi ◽

Wang Boazhen ◽

Ma Fang ◽

Zhang Jinsong ◽

Li Tingjun

Keyword(s):

Mathematical Model ◽

Microbial Communities ◽

Flow Pattern ◽

Rate Constant ◽

Degradation Rate ◽

Heilongjiang Province ◽

Conventional System ◽

Mixed Flow ◽

Pond System ◽

Degradation Rate Constant

A study was carried out on the intensification of a pond system, consisting of an anaerobic pond, a facultative pond and a polishing pond, in Anda City, Heilongjiang Province, by fibrous carriers packed in the anaerobic pond, by means of which the performance of the pond system was remarkably improved with higher removal capacities and efficiencies for SS, BOD5, COD, TN, TP and bacteria, compared with the conventional system. The mechanism for the intensified effect was found to be ascribed to the increase of biomass in the form of biofilm attached to the surface of the fibrous carriers and more even distribution of the biomass in the pond. A mathematical model based on the complete mixed flow pattern was developed both for the intensified and conventional anaerobic pond, and the organic degradation rate constant value K in the former was found to be much greater than that in the latter. The microbial communities in both the ponds were also observed.

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Characterization of textile wastewater and other industrial wastewaters by respirometric and titration biosensors

Water Science & Technology ◽

10.2166/wst.1999.0035 ◽

1999 ◽

Vol 40 (1) ◽

pp. 161-168 ◽

Cited By ~ 6

Author(s):

A. Rozzi ◽

E. Ficara ◽

C. M. Cellamare ◽

G. Bortone

Keyword(s):

Industrial Wastewater ◽

Wastewater Treatment Plants ◽

Oxygen Uptake Rate ◽

Industrial Effluents ◽

Textile Wastewater ◽

Efficient Operation ◽

Autotrophic Bacteria ◽

Degradation Rates ◽

Wastewater Samples

Many industrial effluents, such as textile and tannery wastewater, contain slowly biodegradable, refractory or even toxic compounds at variable concentrations which may interfere with the efficient operation of biological wastewater treatment plants, in particular with the nitrification stage. Agro-industrial effluents may occasionally contain sanitising agents which are by definition biocides. Two different biosensors, based on respirometry (oxygen uptake rate, OUR measurements) and on basic titration respectively, were used to measure degradation rates of industrial wastewater samples by autotrophic bacteria (ammonia oxidizers). Specific sanitisers such as sodium hypochlorite and benzalconium chloride were used to evaluate and compare the nitrifying activity measured by the two different instruments.

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Impact of transverse and longitudinal dispersion on first-order degradation rate constant estimation

Journal of Contaminant Hydrology ◽

10.1016/j.jconhyd.2003.11.004 ◽

2004 ◽

Vol 73 (1-4) ◽

pp. 3-14 ◽

Cited By ~ 24

Author(s):

Greg A. Stenback ◽

Say Kee Ong ◽

Shane W. Rogers ◽

Bruce H. Kjartanson

Keyword(s):

Rate Constant ◽

Degradation Rate ◽

Longitudinal Dispersion ◽

First Order ◽

Degradation Rate Constant

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PENGARUH INTENSITAS CAHAYA TERHADAP DEGRADASI WARNA AGARAGAR YANG DIWARNAI SARI UMBI BIT MERAH (Beta vulgaris L. var. rubra L.)

Agric ◽

10.24246/agric.2013.v25.i1.p42-50 ◽

2016 ◽

Vol 25 (1) ◽

pp. 42

Author(s):

Lydia Ninan Lestario ◽

Noviana Gunawan ◽

Yohanes Martono

Keyword(s):

Light Intensity ◽

Beta Vulgaris ◽

Rate Constant ◽

Degradation Rate ◽

Color Stability ◽

Fluorescent Light ◽

Beetroot Juice ◽

Constant Rate ◽

Degradation Rate Constant ◽

Color Degradation

The aims of this research were to determine the concentration of beetroot juice in jelly which panelists like best; to determine the color degradation rate constant in jelly colored with beetroot juice caused by sunlight and fluorescent light; and color degradation rate constant of jelly colored with synthetic colorant.The organoleptic test used 2,5 percent; 5 percent; 7,5 percent; 10 percent; and 12,5 percent beetroot juice and permitted synthetic colorant for food. The light intensity to test the beetroot color stability in jelly were 879,06 lux, 1.688,54 lux, 2.342,2 lux and 6.752,2 lux.The results showed that the concentration of beetroot juice which panelists like best was 5 percent.; The color degradation rate constant of jelly colored by 5 percent beetroot juice on intensity 879,06 lux was 0,0468 hour-1; 1.688,54 lux was 0,0565 hour-1; 2.342,2 lux was 0,0653 hour-1; 6.752,2 lux was 0,0887 hour-1. The higher the light intensity, the higher the degradation constant rate.

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Cosolvent-free nanocasting synthesis of ordered mesoporous g-C3N4 and its remarkable photocatalytic activity for methyl orange degradation

RSC Advances ◽

10.1039/c5ra13438b ◽

2015 ◽

Vol 5 (94) ◽

pp. 76963-76972 ◽

Cited By ~ 23

Author(s):

Xiaochun Gao ◽

Xuejiao Jiao ◽

Lanchun Zhang ◽

Wencai Zhu ◽

Xiaohong Xu ◽

...

Keyword(s):

Photocatalytic Activity ◽

Methyl Orange ◽

Rate Constant ◽

Degradation Rate ◽

Methyl Orange Degradation ◽

Ordered Mesoporous ◽

Degradation Rate Constant ◽

Nanocasting Route

Ordered mesoporous g-C3N4, synthesized via a green cosolvent-free nanocasting route, exhibited remarkable photodegradation performance towards methyl orange with a degradation rate constant 30 times higher than that of bulk g-C3N4.

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