scholarly journals TiO2-Photocatalyzed Water Depollution, a Strong, yet Selective Depollution Method: New Evidence from the Solar Light Induced Degradation of Glucocorticoids in Freshwaters

2021 ◽  
Vol 11 (6) ◽  
pp. 2486
Author(s):  
Luca Pretali ◽  
Angelo Albini ◽  
Alice Cantalupi ◽  
Federica Maraschi ◽  
Stefania Nicolis ◽  
...  
Keyword(s):  
Tap Water ◽  
Solar Light ◽  
Treatment Efficiency ◽  
Direct Photolysis ◽  
Natural Sunlight ◽  
First Order ◽  
Esi Ms ◽  
Primary Products ◽  
New Evidence ◽  
Aquatic Contaminants

The photodegradation of the most prescribed glucocorticoids (GCs) was studied under relevant environmental conditions in the presence of suspended TiO2. The considered drugs included cortisone (CORT), hydrocortisone (HCORT), betamethasone (BETA), dexamethasone (DEXA), prednisone (PRED), prednisolone (PREDLO), and triamcinolone (TRIAM). The experiments were carried out at concentrations (50 µg L−1) close to the real ones in freshwater samples (tap and river) under simulated and natural sunlight, and their decomposition took place very efficiently under natural sunlight. The reactions were monitored by high-pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). According to a pseudo-first-order decay, all drugs underwent degradation within 15 min, following different paths with respect to the direct photolysis. The observed kinetic constants, slightly lower in river than in tap water, varied from 0.29 to 0.61 min−1 with modest differences among GCs in the same matrix. Among main matrix macro-constituents, humic acids (HAs) were the most interfering species involved in GCs degradation. The photogenerated primary products were identified by HPLC-ESI-MS/MS, allowing to elucidate the general photochemical path of GCs. Finally, a comparison with literature data obtained using different advanced oxidation processes (AOPs) highlights the treatment efficiency with TiO2/solar light for removing such persistent aquatic contaminants.

Photocatalytic Discolouration of Solutions of Reactive Dyes in the Presence of H2O2

1995 ◽  
Vol 30 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Deng Nansheng ◽  
Tian Shizhong ◽  
Xia Mei
Keyword(s):  
Photochemical Reaction ◽  
Uv Light ◽  
Reactive Dyes ◽  
Solar Light ◽  
Rate Equations ◽  
Oh Radical ◽  
Test Results ◽  
Dye Molecules ◽  
First Order ◽  
Dye Solutions

Abstract Tests for the photocatalytic degradation of solutions of three reactive dyes, Red M-5B, Procion Blue MX-R and Procion Black H-N, in the presence of H2O2 were carried out. When the solutions of the three reactive dyes were irradiated by UV or solar light, the colour of the solutions disappeared gradually. A statistical analysis of the test results indicated a linear relation between the concentration of dyes and the time of irradiation. The discolouration reaction of the solutions was of the first order. Rate equations for the discolouration reactions of dye solutions were developed. The dark reactions or the dye solutions containing H2O2 were very slow, illustrating that the photochemical reaction played a very important role. It was demonstrated that UV light and solar light (300 to 380 nm) photolyzes the HO and that the resulting OH radical reacts with the dye molecules and destroys the chromophore.

Area-based speciation kinetic analysis of the multipollutant removal in Constructed Wetlands to enhance its treatment efficiency

2021 ◽  
Author(s):  
Manoj Kumar ◽  
Rajesh Singh
Keyword(s):  
Wastewater Treatment ◽  
Kinetic Analysis ◽  
Constructed Wetlands ◽  
Municipal Wastewater ◽  
Zero Order ◽  
Pollutant Removal ◽  
Municipal Wastewater Treatment ◽  
Treatment Efficiency ◽  
First Order ◽  
Present Study Area

In the present study area-based, pollutant removal kinetic analysis was considered using the Zero-order, first-order decay and efficiency loss (EL) models in the constructed wetlands (CWs) for municipal wastewater treatment....

Removal of sulfonamides from wastewater in the UV/TiO2 system: effects of pH and salinity on photodegradation and mineralization

2019 ◽  
Vol 79 (2) ◽  
pp. 349-355 ◽  
Author(s):  
C. H. Wu ◽  
C. Y. Kuo ◽  
C. D. Dong ◽  
C. W. Chen ◽  
Y. L. Lin
Keyword(s):  
Rate Constants ◽  
Inhibitory Effect ◽  
Chloride Ions ◽  
Mineralization Rate ◽  
Direct Photolysis ◽  
First Order ◽  
First Order Kinetics ◽  
Lower Reactivity ◽  
Chlorine Radicals ◽  
Effects Of Ph

Abstract The effects of salinity on the photodegradation and mineralization of sulfonamides in the UV/TiO2 system were investigated. The goals of this study were to analyze the effects of pH and salinity on the sulfonamide concentration and total organic carbon (TOC) during the removal of sulfonamides in a UV/TiO2 system. Four sulfonamides – sulfadiazine (SDZ), sulfamethizole (SFZ), sulfamethoxazole (SMX) and sulfathiazole (STZ) - were selected as parent compounds. The photodegradation and mineralization rates of sulfonamides in the UV/TiO2 system satisfy pseudo-first-order kinetics. Direct photolysis degraded sulfonamides but sulfonamides cannot be mineralized. The photodegradation and mineralization rate constants in all experiments followed the order pH 5 > pH 7 > pH 9. At pH 5, the mineralization rate constants of SMX, SFZ, SDZ and STZ were 0.015, 0.009, 0.012 and 0.011 min−1, respectively. The addition of NaCl inhibited the mineralization of the four tested sulfonamides more than it inhibited their photodegradation. The inhibitory effect of chloride ions on the removal of sulfonamides in the UV/TiO2 system was attributed to the scavenging by chloride ions of hydroxyl radicals (HO•) and holes and the much lower reactivity of chlorine radicals thus formed, even though the chlorine radicals were more abundant than HO•.

Study on the Alage Removal by Microwave Irradiation

2010 ◽  
Vol 113-116 ◽  
pp. 87-90
Author(s):  
Qing Jie Xie
Keyword(s):  
Activated Carbon ◽  
Microwave Irradiation ◽  
Removal Efficiency ◽  
Oxidation Process ◽  
Removal Rate ◽  
Treatment Efficiency ◽  
Dynamic Reaction ◽  
Initial Concentration ◽  
First Order ◽  
Pollutants Removal

The microwave irradiation (MI) was found that it had significantly treatment efficiency for pollutants removal. It was developed to treat the alage in this paper. The granular activated carbon (GAC) was used as catalyst. The effect of the acting time, MI power, GAC amount and the initial concentration on alage removal were studied. The results showed: with the increasing of the acting time, MI power, GAC amount the alage removal rate were increased, but the effect of the initial concentration to alage removal was opposite; the optimum value of acting time, MI power and GAC amount were 5min, 450W and 3g respectively with the alage removal efficiency reached up to 100%. It also showed that with the alage removed under the MI the COD, SS were removed too. It was discovered that the oxidation process was basically in conformity with the first-order dynamic reaction(ln(C/C0)＝-0.9371t+0.6744（R2=0.9472）).

Photochemistry of a model lignin compound. Spin trapping of primary products and properties of an oligomer

1994 ◽  
Vol 72 (1) ◽  
pp. 35-41 ◽  
Author(s):  
L.R.C. Barclay ◽  
G.R. Cromwell ◽  
J.W. Hilborn
Keyword(s):  
Liquid Chromatography ◽  
Free Radical ◽  
Mass Spectroscopy ◽  
Chemical Ionization ◽  
Spin Trapping ◽  
Direct Photolysis ◽  
Structure Component ◽  
Primary Products ◽  
Model Lignin Compound ◽  
Lignin Structure

α-Guaiacoxylacetoveratrone, 1, was selected as a model of a lignin structure component for photolysis and free radical spin trapping studies. The 3,4-dimethoxyphenacyl radical, Ar-COĊH2, 2, thermally generated from α-bromoacetoveratrone with trimethyltin, was spin trapped by phenyl-tert-butylnitrone (PBN), and the spin-trapped radical identified by ESR and mass spectroscopy. Spin trapping by PBN of radical photoproducts from 1 gave a mixture of trapped radicals, according to ESR. These were separated as their hydroxylamines and identified by liquid chromatography/mass spectroscopy (LC/MS) under chemical ionization (CI) conditions. This LC/MS (CI) method identified the same phenacyl fragment, 2 (reduced), as well as a fragment tentatively attributed to a spin-trapped guaiacoxyl radical, chemically reduced to the hydroxylamine. Extended direct photolysis of 1 yields colored paramagnetic oligomers. The synthesis of 1-(3,4-dimethoxyphenyl)-2-(4-hydroxy-3-methoxyphenylethanone(10), a rearranged, recombination photoproduct of 1, is described. A pathway for formation of oligomers as unstable dimers of 10 is presented.

scholarly journals Comment on: “Interseismic Strain Accumulation near Lisbon (Portugal) from Space Geodesy” by Fonseca et al. (2021)

2021 ◽  
Author(s):  
Luis Matias
Keyword(s):  
Relative Velocity ◽  
Strain Accumulation ◽  
Geophysical Research ◽  
First Order ◽  
Crustal Block ◽  
Tectonic Lineament ◽  
The Moment ◽  
Gnss Data ◽  
Strain Rate Field ◽  
New Evidence

The paper by Fonseca et al. (2021), hereafter referred as FON21, published in Geophysical Research Letters2 make several conclusions that are not convincingly supported by the evidence of the data that is made available. In this comment we will address the following statements: 1) FON21 “provides new evidence of sinistral simple shear driven by a NNE-SSW first-order tectonic lineament; 2) “PSInSAR vertical velocities corroborate qualitatively the GNSS strain-rate field, showing uplift/subsidence where the GNSS data indicate contraction/extension”; 3) FON21 proposes “the presence of a small block to the W of Lisbon moving independently toward the SW with a relative velocity of 0.96 ± 0.20 mm/yr”; 4) FON21 shows “that the contribution of intraplate faults to the seismic hazard in the LMA is more important than currently assumed”. We conclude that more evidence needs to be collected to confirm or infirm FON21 statements and conclusions. For the moment the proposal of an autonomous crustal block moving with significant velocity in relation to the neighboring domain should be considered speculative and unproved.

Photocatalytic degradation of parathion in aqueous TiO2 dispersion: the effect of hydrogen peroxide and light intensity

1998 ◽  
Vol 37 (8) ◽  
pp. 187-194 ◽  
Author(s):  
Tsu-feng Chen ◽  
Ruey-an Doong ◽  
Wen-gang Lei
Keyword(s):  
Hydrogen Peroxide ◽  
Light Intensity ◽  
Photocatalytic Degradation ◽  
Photocatalytic Oxidation ◽  
Pseudo First Order Reaction ◽  
Direct Photolysis ◽  
First Order ◽  
The Relationship ◽  
Effect Of Light ◽  
H2o2 System

The photodegradation of parathion in the direct photolysis, UV/TiO2, UV/H2O2 and UV/TiO2/H2O2 systems was investigated at 25°C. The effect of light intensity was also examined to clarify the relationship between the photo flux and decomposition rate of parathion. Results of the study demonstrated that no obvious degradation of parathion in dark reaction occurred within 24 hours. However, the addition of TiO2 and/or H2O2 promotes the degradation efficiency of parathion. Adding H2O2 was more effective in the photocatalytic oxidation of parathion than TiO2. Also, hydrogen peroxide was found as an intermediate with the maximum concentration of 55 μM in UV/TiO2 system during the photodegradation of parathion. A higher intensity of lamp could increase the degradation rate of parathion. However, the quantum efficiency for degradation of parathion decreased from 0.053 to 0.006 when light intensity increased from 100 W to 450W. Photodecomposition followed a pseudo-first-order reaction. The rate constants of parathion ranged from 0.003 min−1 for direct photolysis to 0.023 min−1 for UV/TiO2/H2O2 system. This study indicated that photocatalytic degradation is a highly promising technology for detoxifying parathion.

Disinfection effects on E. coli using TiO2/UV and solar light system

2002 ◽  
Vol 2 (1) ◽  
pp. 181-190 ◽  
Author(s):  
I.-H. Cho ◽  
I.-Y. Moon ◽  
M.-H. Chung ◽  
H.-K. Lee ◽  
K.-D. Zoh
Keyword(s):  
Light Intensity ◽  
Flow Rate ◽  
Alternative Energy ◽  
Advanced Oxidation Process ◽  
Uv Light ◽  
Solar Light ◽  
Survival Ratio ◽  
E Coli ◽  
First Order ◽  
First Order Kinetics

First, a continuous flow TiO2/UV reactor was designed and developed in order to examine E. coli disinfection effect using UV light. The optimum conditions for disinfection such as flow rate, light intensity, TiO2 concentration, initial E. coli concentration were examined. The results are as follow (i) The use of the quartz device and TiO2 (anatase) resulted in killing of E. coil within minutes. (ii) Photocatalytic disinfection with UV light in the presence of TiO2 more effectively killed E. coli than UV or TiO2 adsorption only. (iii) As flow rate increased, the survival ratio of E. coli decreased, but over 3 L/min of flow rate, the efficiency was limited. (iv) E. coli survival ratio decreased linearly with increasing UV light intensity. (v) The dosage of TiO2 affected the E. coli disinfection efficiency, and above 0.1 wt% TiO2 concentration, the disinfection was less effective because TiO2 particles may result in screening off the light. (ri) The disinfection reaction follows first-order kinetics. Secondly, outdoor experiments with natural sunlight instead of artificial UV light in TiO2 reactors were also conducted to investigate alternative energy source applicability on E. coli disinfection. It is found that the presence of clouds in the sky markedly increased the time required for killing E. coli and the bacteria cells also disappeared with a first-order kinetics. On the basis of these experimental observations, the disinfection of E. coli using TiO2 under solar light irradiation can be a feasible application of the advanced oxidation process.

Co-treatment of septage in a municipal sewage treatment pond system

2002 ◽  
Vol 46 (9) ◽  
pp. 315-321
Author(s):  
B. Kurup ◽  
R. Kurup ◽  
K. Mathew ◽  
G. Ho
Keyword(s):  
Fecal Coliform ◽  
Treatment Options ◽  
Sewage Treatment ◽  
Municipal Sewage ◽  
Treatment Efficiency ◽  
Oil And Grease ◽  
First Order ◽  
Pond System ◽  
First Order Kinetics ◽  
Total Capacity

This paper deals with the characteristics and treatment options of septage. The objective of the paper is to evaluate the effects of co-treatment of 50 MLD of septage in a sewage treatment pond system. The treatment efficiency of the pond system for BOD5 and Fecal Coliform (FC) has been estimated using a first order kinetics model. The model has predicted that the treatment pond system has a maximum capacity of 8.5 MLD and will have a reserve of 28.3% of its total capacity even after the proposed addition of 50 MLD of septage. Separation of oil and grease from septage prior to discharge into the pond system is recommended.

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