scholarly journals Removal of Ampicillin by Heterogeneous Photocatalysis: Combined Experimental and DFT Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1992
Author(s):  
Lenka Belhacova ◽  
Hana Bibova ◽  
Tereza Marikova ◽  
Martin Kuchar ◽  
Radek Zouzelka ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Textural Properties ◽  
Degradation Pathway ◽  
Heterogeneous Photocatalysis ◽  
Reaction Rate Constant ◽  
Radical Scavenger ◽  
Reaction Products ◽  
Degree Of Mineralization ◽  
Ampicillin Concentration ◽  
Nominal Size

A long-term exposition of antibiotics represents a serious problem for the environment, especially for human health. Heterogeneous photocatalysis opens a green way for their removal. Here, we correlated the structural-textural properties of TiO2 photocatalysts with their photocatalytic performance in ampicillin abatement. The tested nanoparticles included anatase and rutile and their defined mixtures. The nominal size range varied from 5 to 800 nm, Aeroxide P25 serving as an industrial benchmark reference. The degradation mechanism of photocatalytic ampicillin abatement was studied by employing both experimental (UPLC/MS/MS, hydroxyl radical scavenger) and theoretical (quantum calculations) approaches. Photocatalytic activity increased with the increasing particle size, generally, anatase being more active than rutile. Interestingly, in the dark, the ampicillin concentration decreased as well, especially in the presence of very small nanoparticles. Even if the photolysis of ampicillin was negligible, a very high degree of mineralization of antibiotic was achieved photocatalytically using the smallest nanoparticles of both allotropes and their mixtures. Furthermore, for anatase samples, the reaction rate constant increases with increasing crystallite size, while the degree of mineralization decreases. Importantly, the suggested degradation pathway mechanism determined by DFT modeling was in very good agreement with experimentally detected reaction products.

scholarly journals Hierarchical TiO2 Layers Prepared by Plasma Jets

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3254
Author(s):  
Radek Zouzelka ◽  
Jiri Olejnicek ◽  
Petra Ksirova ◽  
Zdenek Hubicka ◽  
Jan Duchon ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Advanced Oxidation Processes ◽  
Reaction Rate ◽  
Photocatalytic Performance ◽  
Scale Up ◽  
Textural Properties ◽  
Heterogeneous Photocatalysis ◽  
Reaction Rate Constant ◽  
Plasma Jets ◽  
Physico Chemical

Heterogeneous photocatalysis of TiO2 is one of the most efficient advanced oxidation processes for water and air purification. Here, we prepared hierarchical TiO2 layers (Spikelets) by hollow-cathode discharge sputtering and tested their photocatalytic performance in the abatement of inorganic (NO, NO2) and organic (4-chlorophenol) pollutant dispersed in air and water, respectively. The structural-textural properties of the photocatalysts were determined via variety of physico-chemical techniques (XRD, Raman spectroscopy, SEM, FE-SEM. DF-TEM, EDAX and DC measurements). The photocatalysis was carried out under conditions similar to real environment conditions. Although the abatement of NO and NO2 was comparable with that of industrial benchmark Aeroxide® TiO2 P25, the formation of harmful nitrous acid (HONO) product on the Spikelet TiO2 layers was suppressed. Similarly, in the decontamination of water by organics, the mineralization of 4-chlorophenol on Spikelet layers was interestingly the same, although their reaction rate constant was three-times lower. The possible explanation may be the more than half-magnitude order higher external quantum efficacy (EQE) compared to that of the reference TiO2 P25 layer. Therefore, such favorable kinetics and reaction selectivity, together with feasible scale-up, make the hierarchical TiO2 layers very promising photocatalyst which can be used for environmental remediation.

Efficient degradation of refractory contaminants with silver ferrite for persulfate activation

2019 ◽  
Vol 12 (06) ◽  
pp. 1950083
Author(s):  
Cong Li ◽  
Wei Yang ◽  
Sheng Guo ◽  
Zhixiong Yang ◽  
Hussain Fida ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Degradation Mechanism ◽  
Catalytic Performance ◽  
Degradation Pathway ◽  
Degradation Efficiency ◽  
Radical Scavenger ◽  
Solution Ph ◽  
Practical Applications ◽  
Co Precipitation ◽  
Adsorption Desorption

The advanced oxidation processes (AOPs) based on sulfate radicals have triggered tremendous research efforts in environmental remediation field. In this study, we proposed a facile silver ferrite ([Formula: see text] nanocatalyst via a simple co-precipitation at room temperature. The as-prepared AgFeO2 was characterized by XRD, SEM, TEM, XPS, FTIR and N2 adsorption–desorption techniques and was used for persulfate (PDS) activation for the first time. The result showed that AgFeO2 as a PDS activator exhibited superior degradation efficiency of Rhodamine B (RhB) as compared to bare Ag2O, FeOOH and CuFeO2. Moreover, the AgFeO2 catalyst also demonstrated high degradation efficiency for 4-nitrophenol and Methyl Orange in the presence of PDS. The catalytic performance of AgFeO2 was further evaluated in terms of various parameters, including solution pH, PDS concentration and catalyst dosage. The degradation pathway was proposed based on Liquid Chromatography Mass Spectrometer (LC-MS) result and the degradation mechanism was elucidated through radical scavenger experiments. These findings will extend the scope of novel catalysts for PDS activation and promote the use of AgFeO2 in more practical applications.

Coupled reduction of chlorinated hydrocarbons and heavy metals by zerovalent silicon

2004 ◽  
Vol 50 (8) ◽  
pp. 89-96 ◽  
Author(s):  
R.-A. Doong ◽  
C.-C. Lee ◽  
K.-T. Chen ◽  
S.-F. Wu
Keyword(s):  
Heavy Metals ◽  
Ph Value ◽  
Degradation Mechanism ◽  
Chlorinated Hydrocarbons ◽  
Degradation Pathway ◽  
Reaction Rate Constant ◽  
Contaminated Sites ◽  
Divalent Metal Ions ◽  
First Order Kinetics ◽  
Removal Of Heavy Metals

The feasibility of using zerovalent silicon (Si0) as a novel reductant to remove chlorinated ompounds and heavy metals in contaminated sites was investigated. The kinetics and degradation mechanism of carbon tetrachloride (CT) by Si0 were also examined. Results showed that zerovalent silicon could effectively dechlorinate the chlorinated compounds. A nearly complete dechlorination of CT by Si0 was obtained within 14 h. The produced concentrations of chloroform (CF) accounted for 71-88% loss of CT, showing that reductive dechlorination is the major degradation pathway for the degradation of chlorinated hydrocarbons by Si0. The degradation followed pseudo first-order kinetics and the normalized surface reaction rate constant (ksa) for CT dechlorination ranged between 0.0342 and 0.0454 L m-2 h-1 when CT concentrations were in the range of 3-20 μM. A linear relationship between the ksa and pH value was also established. In addition, zerovalent silicon has a high capability in the removal of heavy metals. 83% of Cr(VI) was removed by 0.5g Si0 within 5 h, which is higher than that by Fe0. The removal efficiency of divalent metal ions by Si0 followed the order of Cu(II) > Pb(II) > Ni(II). This indicates that zerovalent silicon is an alternative reductant and can undergo coupled reduction of heavy metals and chlorinated hydrocarbons in contaminated groundwater.

scholarly journals Impact of Fermentation and Phytase Treatment of Pea-Oat Protein Blend on Physicochemical, Sensory, and Nutritional Properties of Extruded Meat Analogs

Foods ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1059 ◽  
Author(s):  
Aleksei Kaleda ◽  
Karel Talvistu ◽  
Martti Tamm ◽  
Maret Viirma ◽  
Julia Rosend ◽  
...  
Keyword(s):  
Phytic Acid ◽  
Textural Properties ◽  
Amino Acid Profile ◽  
Raw Material ◽  
Process Conditions ◽  
Maillard Reaction Products ◽  
Plant Proteins ◽  
Reaction Products ◽  
Nutritional Properties ◽  
Plant Materials

Plant materials that are used for the production of extruded meat analogs are often nutritionally incomplete and also contain antinutrients, thus there is a need to explore alternative plant proteins and pre-treatments. This study demonstrates application of phytase and fermentation to a pea-oat protein blend with a good essential amino acid profile and subsequent texturization using extrusion cooking. Enzymatic treatment reduced the content of antinutrient phytic acid by 32%. Extrusion also degraded phytic acid by up to 18%, but the effect depended on the material. Differences in physicochemical, sensorial, and textural properties between untreated and phytase-treated extruded meat analogs were small. In contrast, fermented material was more difficult to texturize due to degradation of macromolecules; physicochemical and textural properties of extrudates were markedly different; sensory analysis showed enhancement of flavor, but also detected an increase in some unwanted taste attributes (bitterness, cereal and off-taste). Phytic acid was not degraded by fermentation. Analysis of volatile compounds showed extrusion eliminated volatiles from the raw material but introduced Maillard reaction products. Overall, phytase treatment and fermentation demonstrated the potential for application in extruded meat analogs but also highlighted the necessity of optimization of process conditions.

scholarly journals Study on the mechanism of degradation of tetracycline hydrochloride by microwave-activated sodium persulfate

2020 ◽  
Vol 82 (9) ◽  
pp. 1961-1970
Author(s):  
Yu Gao ◽  
Shibo Cong ◽  
Yulun He ◽  
Donglei Zou ◽  
Yuzhi Liu ◽  
...  
Keyword(s):  
High Performance ◽  
Degradation Pathway ◽  
Tetracycline Hydrochloride ◽  
Radical Scavenger ◽  
Sodium Persulfate ◽  
Liquid Chromatography Mass Spectrometry ◽  
Operational Parameters ◽  
Mechanism Of Degradation ◽  
Initial Ph ◽  
Concentration Changes

Abstract Among the different antibiotics, tetracycline hydrochloride (TCH) is one of the most commonly used. In this study, the activated sodium persulfate (SPS) process induced by microwave (MW) energy was used to treat TCH. The effect of different operational parameters of MW/SPS-treated TCH, such as SPS concentration, TCH concentration, initial pH, and MW power, was investigated. The concentration changes of TCH were determined using a spectrophotometer. The results of radical scavenger experiments indicated that the sulfate radical () was stronger than the hydroxyl radical (·OH). On the basis of high performance liquid chromatography–mass spectrometry (HPLC–MS) analysis, a possible degradation pathway of TCH was proposed. This research indicates that the MW/SPS system is a promising prospect for the treatment of TCH.

Ultrasonic Irradiation Of The Removal Of Linear Alkylbenzene Sulphonates (LAS) From Wastewater

2012 ◽  
Author(s):  
Mohd Ariffin Abu Hassan ◽  
Dionissios Mantzavinos ◽  
Ian S. Metcalfe
Keyword(s):  
Ultrasonic Irradiation ◽  
Surfactant Concentration ◽  
Degradation Rate ◽  
Degradation Mechanism ◽  
Low Frequency ◽  
Degradation Pathway ◽  
H2o2 Production ◽  
Oh Radicals ◽  
Linear Alkylbenzene ◽  
Batch Time

Kesan frekuensi rendah (20 kHz) penyinaran ultrasonik untuk penyingkiran Linear Alkylbenzene Sulphonates (LAS) daripada larutan berair telah dikaji. Penyinaran ultrasonik terhadap tiga kepekatan berbeza LAS iaitu 500 μgmol/l, 750 μgmol/l and 1000 μgmol/l telah dijalankan. Kesemua eksperimen telah dijalankan pada suhu 30°C, pada frekuensi 20 kHz, kuasa pada 125 W dan masa eksperimen selama 120 minit tanpa pengawalan terhadap pH. Hasil kajian mendapati OH· radikal mendominasi proses pengdegradasian LAS. Kadar degradasi awal bertambah dengan bertambahnya kepekatan LAS di dalam skop kajian. Penghasilan H2O2 didapati rendah dengan proses penyinaran ultrasonik terhadap LAS pada kepekatan LAS yang tinggi. Keputusan penyinaran ultrasonik terhadap LAS dengan kehadiran Br¯ sebagai pemakan radikal membuktikan bahawa OH· radikal mendominasi pengdegradasian LAS. Kata kunci: Surfaktan, ultrasonik, sisa air, jumlah karbon organik (TOC) The effect of low frequency (20 kHz) ultrasonic irradiation on the removal of sodium Linear Alkylbenzene Sulphonates (LAS) from aqueous solutions has been investigated. Sonication of three different initial concentrations of LAS, 500 μgmol/l, 750 μgmol/l and 1000 μgmol/l, were performed. All experiments used a temperature of 30°C, frequency of 20 kHz, power of 125 W, a batch time of 120 min and the pH was left uncontrolled. It was found that the main degradation of LAS at micromolar concentrations proceeded via a reaction with OH· radicals. The initial degradation rate increased with an increase in the surfactant concentration over the whole concentration range studied. The sonolysis of LAS showed a strong inhibition of H2O2 production at a higher concentration. Sonication of LAS in the presence of Br¯ suggested that OH· radicals induced degradation pathway was the dominating sonochemical degradation mechanism. Key words: Surfactants, ultrasonic, wastewater, total organic carbon (TOC)

scholarly journals 2D In-Plane CuS/Bi2WO6 p-n Heterostructures with Promoted Visible-Light-Driven Photo-Fenton Degradation Performance

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1151 ◽  
Author(s):  
Li Guo ◽  
Kailai Zhang ◽  
Xuanxuan Han ◽  
Qiang Zhao ◽  
Danjun Wang ◽  
...  
Keyword(s):  
Visible Light ◽  
Large Scale ◽  
Separation Efficiency ◽  
Degradation Mechanism ◽  
Visible Region ◽  
Catalytic Performance ◽  
Degradation Efficiency ◽  
Radical Scavenger ◽  
Strong Reaction ◽  
Practical Applications

Photo-Fenton degradation of pollutants in wastewater is an ideal choice for large scale practical applications. Herein, two-dimensional (2D) in-plane CuS/Bi2WO6 p-n heterostructures have been successfully constructed by an in situ assembly strategy and characterized using XRD, XPS, SEM/TEM, EDX, UV-Vis-DRS, PL, TR-PL, ESR, and VB-XPS techniques. The XPS and the TEM results confirm the formation of CuS/Bi2WO6 heterostructures. The as-constructed CuS/Bi2WO6 showed excellent absorption in visible region and superior charge carrier separation efficiency due to the formation of a type-II heterojunctions. Under visible light irradiation, 0.1% CuS/Bi2WO6 heterostructure exhibited the best photo-Fenton-like catalytic performance. The degradation efficiency of Rhodamine B (RhB, 20 mg·L−1) can reach nearly 100% within 25 min, the apparent rate constant (kapp/min−1) is approximately 40.06 and 3.87 times higher than that of pure CuS and Bi2WO6, respectively. The degradation efficiency of tetracycline hydrochloride (TC-HCl, 40mg·L−1) can reach 73% in 50 min by employing 0.1% CuS/Bi2WO6 heterostructure as a photo-Fenton-like catalyst. The promoted photo-Fenton catalytic activity of CuS/Bi2WO6 p-n heterostructures is partly ascribed to its low carriers recombination rate. Importantly, CuS in CuS/Bi2WO6 heterostructures is conducive to the formation of heterogeneous photo-Fenton catalytic system, in which Bi2WO6 provides a strong reaction site for CuS to avoid the loss of Cu2+ in Fenton reaction, resulting in its excellent stability and reusability. The possible photo-Fenton-like catalytic degradation mechanism of RhB and TC-HCl was also elucidated on the basis of energy band structure analysis and radical scavenger experiments. The present study provides strong evidence for CuS/Bi2WO6 heterostructures to be used as promising candidates for photo-Fenton treatment of organic pollutants.

Intermediate Products Analysis of Phenol Degradation in Aqueous Solution Caused by Pulsed Discharge

2012 ◽  
Vol 518-523 ◽  
pp. 3146-3149
Author(s):  
Sheng Lan ◽  
Zhen Xing Zhang ◽  
Yong Bin Yuan ◽  
Abdus Samee
Keyword(s):  
Aqueous Solution ◽  
Degradation Mechanism ◽  
Pulse Discharge ◽  
Phenol Degradation ◽  
Reaction Products ◽  
Pulsed Discharge ◽  
Dc Voltage ◽  
Intermediate Products ◽  
Phenethyl Alcohol ◽  
Products Analysis

Abstract. In this paper we have presented the degradation of Phenol in aqueous solution which is caused by pulse discharge. The reaction products in the wastewater dissolved phenol under pulsed discharge were tested using GC-MS. Based on the experimental results intermediate products include 2,4hydroxyphnel, polyhydroxy phenethyl alcohol and so on. The final products are carbon dioxide and water. In addition, the theoretical analysis has been conducted These results will be helpful for further studying degradation mechanism of wastewater dissolved phenol under pulsed discharge, using either AC or DC voltage.

scholarly journals Photo fenton like process Fe3+/(NH4)2S2O8/UV for the degradation of Di azo dye congo red using low iron concentration

2009 ◽  
Vol 7 (3) ◽  
pp. 468-477 ◽  
Author(s):  
L. Devi ◽  
S. Kumar ◽  
K. Reddy
Keyword(s):  
Congo Red ◽  
Azo Dye ◽  
Degradation Mechanism ◽  
Iron Concentration ◽  
Catalytic Efficiency ◽  
Ammonium Persulfate ◽  
Process Efficiency ◽  
Radical Scavenger ◽  
Hydroxyl Radical Scavenger ◽  
Acidic Conditions

AbstractDegradation of Congo Red (CR) a di azo dye in aqueous solution is investigated by a Photo Fenton like process using Fe3+ ions as the catalyst and peroxy disulfate as the oxidant. The influence of various reaction parameters like, concentration of Fe3+ ions, concentration of the dye, concentration of ammonium persulfate, pH of the solution and the presence of hydroxyl radical scavenger are studied and optimal conditions are reported. The degradation rate decreased at higher dye concentration and at higher pH. The rate constant (k), catalytic efficiency (kc) and process efficiency (Φ) are evaluated for different concentration of Fe3+ ions. The degradation of CR by the photo Fenton like process leads to the formation of 4-Amino, 3-azo naphthalene sulphonic acid, dihydroxy substituted naphthalene, dihydroxy substituted biphenyl, phenol, quinol etc., as intermediates, based on which probable degradation mechanism is proposed. These results show that a photo Fenton like process could be useful technology for the mineralization of di azo dyes under lower concentration of iron in acidic conditions. The present process is advantageous as it lowers the sludge production resulting from the iron comple

Photocatalytic Decomposition of Metoprolol and Its Intermediate Organic Reaction Products: Kinetics and Degradation Pathway

2016 ◽  
Vol 14 (3) ◽  
pp. 809-820 ◽  
Author(s):  
Alfonso Pinedo ◽  
Mariana López ◽  
Elisa Leyva ◽  
Brenda Zermeño ◽  
Benito Serrano ◽  
...  
Keyword(s):  
Uv Light ◽  
Reaction Pathway ◽  
Kinetic Studies ◽  
Initial Reaction Rate ◽  
Degradation Pathway ◽  
Photocatalytic Decomposition ◽  
Initial Reaction ◽  
Low Molecular Weight ◽  
Reaction Products ◽  
Constant Flow Rate

Abstract High purity metoprolol prepared by neutralization of an aqueous solution of metoprolol tartrate is efficiently mineralized to CO2 and water by photocatalysis with TiO2, UV light and a constant flow rate of oxygen. Since the tartrate anions were eliminated, all the HO• generated by photocatalysis reacted efficiently with the aromatic part of the medication. The reaction pathway includes two routes of degradation. The first one includes the transformation of metoprolol to hydroquinone via formation of 4-(2-methoxyethyl)phenol, 2-(4-hydroxyphenyl)ethanol and 4-hydroxybenzaldehyde. Metoprolol is also degraded directly to hydroquinone. Then, this aromatic compound is oxidized to 1,2,4-benzenetriol, which is rapidly oxidized to low molecular weight organic acids before being completely mineralized to CO2 and water. Kinetic studies indicated that the initial reaction rate of the degradation of metoprolol, 4-(2-methoxyethyl)phenol, 2-(4-hydroxyphenyl)ethanol and 4-hydroxybenzaldehyde is described by the LH-HW model.

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