Solar Photocatalytic Degradation of Sulfamethoxazole by TiO2 Modified with Noble Metals

Application of solar photocatalysis for water treatment is intensively studied. In this work, we investigated TiO2 modified with platinum (Pt/TiO2) and palladium (Pd/TiO2) using sulfamethoxazole (SMX) as the model contaminant. We considered the following parameters: (i) level of TiO2 modification with Pt/Pd, (ii) initial concentration of photocatalysts, (iii) geographic location where processes were conducted, and (iv) natural water matrix. The catalysts characterized by SEM, EDX, DRS, and XRD techniques showed successful deposition of Pd and Pt atoms on TiO2 surface that enabled light absorption in the visible (Vis) range, and therefore caused efficient SMX removal in all tested conditions. A comparison of the rate constants of SMX degradation in various conditions revealed that modification with Pd gave better results than modification with Pt, which was explained by the better optical properties of Pd/TiO2. The removal of SMX was higher with Pd/TiO2 than with Pt/TiO2, independent of the modification level. In the experiments with the same modification level, similar rate constants were achieved when four times the lower concentration of Pd/TiO2 was used as compared with Pt/TiO2. Formation of four SMX transformation products was confirmed, in which both amine groups are involved in photocatalytic oxidation. No toxic effect of post-reaction solutions towards Lepidium sativum was observed.

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Comparison of radical-driven technologies applied for paraben mixture degradation: mechanism, biodegradability, toxicity and cost assessment

Environmental Science and Pollution Research ◽

10.1007/s11356-019-06703-9 ◽

2019 ◽

Vol 26 (36) ◽

pp. 37174-37192 ◽

Cited By ~ 1

Author(s):

Marta Gmurek ◽

João F. Gomes ◽

Rui C. Martins ◽

Rosa M. Quinta-Ferreira

Keyword(s):

Photocatalytic Oxidation ◽

Degradation Mechanism ◽

Transformation Products ◽

Degradation Pathway ◽

Toxicity Assessment ◽

Degradation Efficiency ◽

Lepidium Sativum ◽

Cost Assessment ◽

Aqueous Environment ◽

Photocatalytic Ozonation

AbstractParabens (esters of p-hydroxybenzoic acid) are xenobiosis belonging to endocrine disruptors and commonly used as a preservative in cosmetics, food, pharmaceutical, and personal care products. Their wide use is leading to their appearance in water and wastewater in the range from ng/L to mg/L. In fact, the toxicity of benzylparaben is comparable to bisphenol A. Therefore, it is important to find not only effective but also ecofriendly methods for their removal from aqueous environment since the traditional wastewater treatment approaches are ineffective. Herein, for the first time, such extended comparison of several radical-driven technologies for paraben mixture degradation is presented. The detailed evaluation included (1) comparison of ozone and hydroxyl peroxide processes; (2) comparison of catalytic and photocatalytic processes (including photocatalytic ozonation); (3) characterisation of catalysts using SEM, XRD, DRS, XPS techniques and BET isotherm; (4) mineralisation, biodegradability and toxicity assessment; and (5) cost assessment. O3, H2O2/Fe2+, H2O2/UVC, O3/H2O2, O3/UVA, O3/H2O2/UVA, UVA/catalyst, O3/catalyst and O3/UVA/catalyst were selected from advanced oxidation processes to degrade parabens as well as to decrease its toxicity towards Aliivibrio fischeri, Corbicula fluminea and Lepidium sativum. Research was focused on the photocatalytic process involving visible light (UVA and natural sunlight) and TiO2 catalysts modified by different metals (Ag, Pt, Pd, Au). Photocatalytic oxidation showed the lowest efficiency, while in combining ozone with catalysis and photocatalysis process, degradation efficiency and toxicity removal were improved. Photocatalytic ozonation slightly improved degradation efficiency but appreciably decreased transferred ozone dose (TOD). Results indicate that the degradation pathway is different, or different transformation products (TPs) could be formed, despite that the hydroxyl radicals are the main oxidant.

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Inorganic greywater matrix impact on photocatalytic oxidation: does flocculation of TiO2 nanoparticles impair process efficiency?

Water Science & Technology ◽

10.2166/wst.2011.614 ◽

2011 ◽

Vol 63 (12) ◽

pp. 2808-2813 ◽

Cited By ~ 8

Author(s):

A. Armanious ◽

A. Özkan ◽

U. Sohmen ◽

H. Gulyas

Keyword(s):

Rate Constants ◽

Electric Double Layer ◽

Photocatalytic Oxidation ◽

Process Efficiency ◽

Point Of Zero Charge ◽

Inorganic Salts ◽

Co2 Absorption ◽

Oh Radical ◽

Radical Scavengers ◽

Subsequent Formation

This study was conducted in order to clarify whether photocatalyst flocculation – as observed in biologically pretreated greywater – contributes to photocatalytic oxidation (PCO) efficiency impairment. Aqueous solutions of tetraethyleneglycol dimethylether spiked with different inorganic salts in concentrations as found in biologically treated greywater were investigated with respect to TiO2 flocculation and PCO mineralisation kinetics. Flocculation of the photocatalyst primarily depended on pH (which was affected by the salts) and how close pH was to the point of zero charge (PZC). Photocatalyst agglomeration was maximum at pH 5.5. With salt concentrations >7 mmol L−1, flocculation was strong even at pH far above PZC due to electric double layer compression. PCO rate constants were not unequivocally related to flocculation. Increasing pH was observed as the clearest factor deteriorating PCO efficiency. This was interpreted to result from impaired adsorbability of negatively charged oxidation intermediates as well as from enhanced CO2 absorption with increasing pH and subsequent formation of HCO3− anions which are OH radical scavengers.

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Biosensor-Attached DNA and DNA in Solution Hybridize with the Similar Rate Constants

Biosensors '94 ◽

10.1016/b978-1-85617-242-4.50101-4 ◽

1994 ◽

pp. 126

Author(s):

Newton C. Fawcett ◽

Robert B. Towery ◽

Ping Zhang ◽

Jeffrey A. Evans

Keyword(s):

Rate Constants ◽

Similar Rate

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UV-Fenton degradation of diclofenac, sulpiride, sulfamethoxazole and sulfisomidine: Degradation mechanisms, transformation products, toxicity evolution and effect of real water matrix

Chemosphere ◽

10.1016/j.chemosphere.2020.127351 ◽

2020 ◽

Vol 258 ◽

pp. 127351 ◽

Cited By ~ 4

Author(s):

Mianwei Hong ◽

Yang Wang ◽

Gang Lu

Keyword(s):

Transformation Products ◽

Degradation Mechanisms ◽

Water Matrix

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Solar Light Photoactive Floating Polyaniline/TiO2 Composites for Water Remediation

Nanomaterials ◽

10.3390/nano11113071 ◽

2021 ◽

Vol 11 (11) ◽

pp. 3071

Author(s):

Ermelinda Falletta ◽

Anna Bruni ◽

Marta Sartirana ◽

Daria C. Boffito ◽

Giuseppina Cerrato ◽

...

Keyword(s):

Rhodamine B ◽

Transformation Products ◽

Water Remediation ◽

Solar Light ◽

Reaction Conditions ◽

Doping Agent ◽

Water Matrix ◽

Physico Chemical ◽

Materials Behavior

In the present study, the development of innovative polyurethane-polyaniline/TiO2 modified floating materials applied in the sorption and photodegradation of rhodamine B from water matrix under solar light irradiation is reported. All the materials were fabricated with inexpensive and easy approaches and were properly characterized. The effect of the kind of polyaniline (PANI) dopant on the materials’ behavior was investigated, as well as the role of the conducting polymer in the pollutant abatement on the basis of its physico-chemical characteristics. Rhodamine B is removed by adsorption and/or photodegradation processes depending on the type of doping agent used for PANI protonation. The best materials were subjected to recycle tests in order to demonstrate their stability under the reaction conditions. The main transformation products formed during the photodegradation process were identified by ultraperformance liquid chromatography-mass spectrometry (UPLC/MS). The results demonstrated that photoactive floating PANI/TiO2 composites are useful alternatives to common powder photocatalysts for the degradation of cationic dyes.

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Removal of Emerging Contaminants in Wastewater by Sonolysis, Photocatalysis and Ozonation

Global NEST Journal ◽

10.30955/gnj.002625 ◽

2018 ◽

Vol 21 (2) ◽

pp. 98-105 ◽

Cited By ~ 1

Keyword(s):

Rate Constants ◽

Photocatalytic Oxidation ◽

Advanced Oxidation Processes ◽

Emerging Contaminants ◽

Removal Rate ◽

Experimental Conditions ◽

Oxidation Processes ◽

First Order ◽

Performance Variation ◽

Pseudo First Order

<p>Three different advanced oxidation processes (AOPs) were applied to investigate the removal of emerging contaminants (ECs) i.e. sulfamethoxazole (SMX), diclofenac (DCF) and carbamazepine (CBZ) in synthetically prepared solutions. The degradation of these substances was carried out by ozonation, sonolysis and photocatalytic oxidation, as well as by different combinations of these processes. The objectives of this work were to evaluate the removal efficiency in each AOP and to assess the performance variation of sonolysis in combination with other AOPs. The best performances were achieved by sonocatalysis, which resulted in the removal of the selected pharmaceuticals in the range between 37% and 47%. Under similar experimental conditions, the removal of the selected ECs by single compounds by ozonation was slightly lower than the removal of respective compounds in the mixture. Moreover, pseudo first-order removal rate constants of photocatalytic mineralization were determined as 9.33×10-2, 4.90×10-3, 1.06×10-2 min-1 for SMX, DCF and CBZ, respectively.</p>

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Intermolecular hydrogen tunneling in solids. Comparison between diabatic and adiabatic rate expressions

Canadian Journal of Chemistry ◽

10.1139/v88-150 ◽

1988 ◽

Vol 66 (4) ◽

pp. 875-880 ◽

Cited By ~ 5

Author(s):

Philip D. Pacey ◽

Willem Siebrand

Keyword(s):

Rate Constants ◽

Potential Energy Surfaces ◽

Degrees Of Freedom ◽

Hydrogen Transfer ◽

Hydrogen Abstraction ◽

Golden Rule ◽

Slow Motion ◽

Similar Rate ◽

State Theory ◽

Rate Expression

Rate expressions are derived for hydrogen transfer between two molecules in a solid, typical examples being hydrogen abstraction by methyl radicals in solid methane and in glassy methanol. These expressions are based on two-dimensional potential-energy surfaces describing the motion of the hydrogen atom along with that of the atoms between which it is transferred. A diabatic rate expression, based on the Golden Rule, is compared with an adiabatic rate expression, based on transition-state theory with a tunneling correction. In both cases, the two degrees of freedom must be treated quantum-mechanically rather than classically. For the adiabatic case, this leads to a new expression in which the barrier permeability is averaged over the wavefunction of the slow motion. The result differs from the Golden-Rule expression but yields similar rate constants. Numerical estimates are presented to illustrate the temperature and isotope dependence of these rate constants. The concept of a tunneling path is shown to break down at low temperature, so that the conventional one-dimensional tunneling approach becomes invalid.

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Abatement of formaldehyde with photocatalytic and catalytic oxidation: a review

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0003 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Vipin Soni ◽

Varun Goel ◽

Paramvir Singh ◽

Alok Garg

Keyword(s):

Catalytic Oxidation ◽

Transition Metal Oxides ◽

Noble Metals ◽

Photocatalytic Oxidation ◽

Indoor Environments ◽

Preparation Methods ◽

Nasal Tumors ◽

Domestic Products ◽

Control Study ◽

Effect Of Light

AbstractFormaldehyde is one of the vital chemicals produced by industries, transports, and domestic products. Formaldehyde emissions adversely affect human health and it is well known for causing irritation and nasal tumors. The major aim of the modern indoor formaldehyde control study is in view of energy capacity, product selectivity, security, and durability for efficient removal of formaldehyde. The two important methods to control this harmful chemical in the indoor environments are photocatalytic oxidation and catalytic oxidation with noble metals and transition metal oxides. By harmonizing different traditional photocatalytic and catalytic oxidation technologies that have been evolved already, here we give a review of previously developed efforts to degrade indoor formaldehyde. The major concern in this article is based on getting the degradation of formaldehyde at ambient temperature. In this article, different aspects of these two methods with their merits and demerits are discussed. The possible effects of operating parameters like preparation methods, support, the effect of light intensity in photocatalytic oxidation, relative humidity, etc. have been discussed comprehensively.

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