scholarly journals Comparison of Ag and AgI-Modified ZnO as Heterogeneous Photocatalysts for Simulated Sunlight Driven Photodegradation of Metronidazole

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1097 ◽  
Author(s):  
Chao Ding ◽  
Kun Fu ◽  
Yishuai Pan ◽  
Jia Liu ◽  
Huiping Deng ◽  
...  
Keyword(s):  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
Oxygen Species ◽  
Simulated Sunlight ◽  
Photocatalytic Process ◽  
Critical Part ◽  
Initial Concentration ◽  
Ph Values ◽  
The Stability

Ag and AgI-modified ZnO composites (Ag/ZnO and AgI/ZnO) were synthesized in facile ways. The photocatalysts were used for the photodegradation of metronidazole (MNZ) under the irradiation of simulated sunlight. The results of experiments showed that both Ag/ZnO and AgI/ZnO had a specific molar ratio to reach the best performance. Ag/ZnO performed better in the photodegradation of MNZ than AgI/ZnO under the same conditions. The reaction rate constant of AgI/ZnO was less affected by the variation of initial concentration of MNZ or pH values. The main reactive oxygen species of the photocatalytic process are OH, O2− and h+, but the free radicals which play the most critical part differ in Ag/ZnO and AgI/ZnO. Several intermediates were revealed by LC–MS/MS analysis. The stability of the photocatalysts was evaluated by a series of repeated MNZ photodegradation experiments. The results showed that AgI/ZnO had better stability than Ag/ZnO.

An Investigation into the Conversion of Propylene Glycol to 2,4-dimethyl-1,3-dioxolane over an Acid Catalyst Using Gas Chromatography

2013 ◽  
Vol 850-851 ◽  
pp. 82-85
Author(s):  
Zuo You Zhang ◽  
Hui Chen ◽  
Xia Li ◽  
Zhao Hui Yang ◽  
Bao Chen Liang
Keyword(s):  
Aqueous Solution ◽  
Reaction Rate ◽  
Acid Catalyst ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Molar Ratio ◽  
Temperature Reaction ◽  
Gas Chromatograph ◽  
Second Order Reaction ◽  
Operational Parameters

In the presence of an acid catalyst, PG react reversibly with acetaldehyde to form 2,4-dim-ethyl-1,3-dioxolane (24DMD). The effects of different operational parameters on PG conversion had been analyzed in paper, parameters included temperature, reaction time, amount of catalyst and aqueous acetaldehyde/PG molar ratio. Under optimal condition, 85% conversion of PG in aqueous solution was achieved within 180 min of reaction. The analysis of PG was conducted by gas chromatograph. Furthermore, reaction followed the second-order reaction kinetics, and the reaction rate constant was found to be 29.68min-1.

scholarly journals Investigating the Effects of Ultrasonic Frequency and Membrane Technology on Biodiesel Production from Chicken Waste

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2133
Author(s):  
Seyyedeh Faezeh Mirab Haghighi ◽  
Payam Parvasi ◽  
Seyyed Mohammad Jokar ◽  
Angelo Basile
Keyword(s):  
Reaction Rate ◽  
Design Method ◽  
Polynomial Equation ◽  
Membrane System ◽  
Reaction Rate Constant ◽  
Operating Conditions ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Ultrasonic Frequency ◽  
Biodiesel Synthesis

In this study, the experiments were carried out under different operating conditions to evaluate the effect of ultrasound waves on biodiesel production from chicken feet oil. A two-step esterification–transesterification mechanism was employed to improve the biodiesel quality. The continuous (methanol-to-oil molar ratio and KOH catalyst amount) and discrete (frequencies, 25 and 45 kHz) variables were investigated using the experimental design method. The five-level three-factor response surface method (RSM) was assisted to optimize the biodiesel synthesis variables. Applying RSM based on the central composite design (CCD), a polynomial equation was fitted to the experimental data with the aid of Design-Expert software. The model accuracy was checked by analysis of variance (ANOVA). The results showed the highest yield of 89.74% could be achieved by using an M/O molar ratio of 12, a KOH concentration of 1 wt%, and an ultrasound frequency of 45 kHz. Finally, a mathematical model of biodiesel production in a membrane system was developed. The reaction rate constant was calculated as a function of ultrasonic frequency. Compared with the conventional method, the membrane system has significantly improved chicken feet biodiesel production’s reaction rate. The membrane is more effective at higher frequencies than at lower ones.

Photocatalytic Degradation of Bisphenol AF in TiO2 Suspension

2014 ◽  
Vol 955-959 ◽  
pp. 2334-2339
Author(s):  
Pin Wen Wang
Keyword(s):  
Photocatalytic Degradation ◽  
Reaction Rate ◽  
Degradation Kinetics ◽  
Fluoride Concentration ◽  
Reaction Rate Constant ◽  
Rate Model ◽  
Initial Concentration ◽  
Fluoride Pollution ◽  
Kinetics Of ◽  
Bisphenol Af

The photodegradation behavior of bisphenol AF (BPAF) in TiO2 suspension was investigated. The influence of dissolved oxygen, TiO2 dosage, fluoride, and initial BPAF concentration on the degradation of BPAF was studied and described in details. The main purposes were to clarify the degradation kinetics of BPAF and quantify the fluoride concentration during the degradation. At an initial concentration of 40 mol/L, more than 97% of TOC was removed efficiency was achieved within 540 min irradiation, and the concentration of fluoride was 0.98 mg/L. Degradation of BPAF followed the Langmuir–Hinshelwood kinetics rate model and the reaction rate constant kre was 1.21 μM/min. The results obtained indicated that TiO2 photocatalytic degradation is a highly effective way to remove BPAF without any generation of more toxic products or fluoride pollution.

scholarly journals Hydrothermal synthesis of monocopper sulfide for hydrogen peroxide-assisted photodegradation of paraquat

2020 ◽  
Vol 26 (1) ◽  
Author(s):  
Rattabal Khunphonoi ◽  
Kitirote Wantala ◽  
Nurak Grisdanurak
Keyword(s):  
Photoelectron Spectroscopy ◽  
Reaction Rate ◽  
Ageing Time ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Energy Band Gap ◽  
X Ray ◽  
Synthesis Parameters ◽  
Transmission Electron

Copper sulfide was prepared by a hydrothermal method at 130°C. The copper to sulfur molar ratio (6-10) and ageing time (24-72 h) were their synthesis parameters. The obtained materials were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscope (TEM), UV-DR spectroscopy and X-ray photoelectron spectroscopy (XPS). In order to obtain monocopper sulfide, CuS, named as covellite, the molar recipe ratio of sulfur to copper should be less than 8 in any hydrothermal ageing time. The morphology showed spherical-like structure with energy band gap of 1.88-2.04 eV. CuS was tested for its photocatalytic degradation of paraquat under visible light irradiation. It exhibited excellent activities in the presence of H<sub>2</sub>O<sub>2</sub>. The kinetic of paraquat degradation was also investigated using Langmuir-Hinshelwood-Hougen-Watson (LHHW) model. The reaction rate constant was three times higher than TiO<sub>2</sub> under the same studied conditions.

scholarly journals Kinetics of heterogeneous methanolysis of sunflower oil with CaO∙ZnO catalyst: Influence of different hydrodynamic conditions

2014 ◽  
Vol 20 (3) ◽  
pp. 425-439 ◽  
Author(s):  
Ivana Lukic ◽  
Zeljka Kesic ◽  
Svetolik Maksimovic ◽  
Miodrag Zdujic ◽  
Jugoslav Krstic ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Rate Constant ◽  
Sunflower Oil ◽  
Reaction Rate ◽  
Catalyst Surface ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
Model Parameters ◽  
Pseudo First Order Reaction ◽  
Kinetics Of

The kinetics of heterogeneous methanolysis of sunflower oil was studied at 60?C using mechanochemically synthesized CaO?ZnO as catalyst. Influence of agitation speed, catalyst amount and methanol to oil molar ratio on the rate of reaction was analyzed. The rate of the process depends on the two resistances - mass transfer of triglycerides to the catalyst surface and chemical reaction on the catalyst surface, which are defined as the values of the overall triglyceride volumetric mass transfer coefficient, kmt,TG, and the effective pseudo first-order reaction rate constant, k, respectively. These kinetic parameters actually determine the value of the apparent reaction rate constant, kapp, whose change with time is defined with the change of triglyceride (TG) conversion. The kinetic model was proposed and the model parameters determined.

scholarly journals In Vitro Study of MefenamateStarch as Drug Delivery System

2013 ◽  
Vol 10 (3) ◽  
pp. 954-964
Author(s):  
Baghdad Science Journal
Keyword(s):  
In Vitro Study ◽  
Controlled Drug Release ◽  
Gastric Fluid ◽  
Molar Ratio ◽  
Ph Values ◽  
Ft Ir ◽  
Uv Visible ◽  
The Stability ◽  
Hydrolysis Of

Mefenamic acid was esterified with starchwith[1:1] Molar ratio, as drug substituted with natural polymer, to prolongthe period of hydrolysis of drug polymer with other advantages. The new prodrug starch was characterized by FT-IR and UV-Visible and 1H-NMR spectroscopies. The physical properties were studied and controlled drug release was studied in different pH values at 37oC. The stability of drug was carried out by measuring the absorbance of mefenamic starch which hydrolyzed in HCl solution of pH 1.1 (artificial gastric fluid) and phosphate buffer of pH 7.4 (simulating intestinal fluid SIF) at 37oC for several days. The thermal analysis such as DSC was studied.

Effect of OH- Concentration on Alkaline Hydrolysis of Diphenyl (4-Nitrophenyl) Phosphate Catalyzed by 2-Iodosobenzoic and 3-Iodoso-2-naphthoic Acids

1994 ◽  
Vol 59 (5) ◽  
pp. 1137-1144 ◽  
Author(s):  
Aleš Ptáček ◽  
Jiří Kulič
Keyword(s):  
Alkaline Hydrolysis ◽  
Reaction Rate ◽  
Ion Concentration ◽  
Molar Ratio ◽  
Hexadecyltrimethylammonium Bromide ◽  
Ph Values ◽  
Nitrophenyl Phosphate ◽  
Naphthoic Acid ◽  
Iodosobenzoic Acid ◽  
Hydrolysis Of

The hydrolysis of diphenyl (4-nitrophenyl) phosphate catalyzed by 2-iodosobenzoic and 3-iodoso-2-naphthoic acids has been studied at different pH values in the presence of hexadecyltrimethylammonium bromide as a micellar agent. It was found that 3-iodoso-2-naphthoic acid is better catalyst than 2-iodosobenzoic acid. At amounts of the acids higher than stoichiometric, the reaction is independent of pH in the 8.00 to 10.00 region while on using substoichiometric amounts, the reaction rate depends on OH- ion concentration only when the acid to diphenyl (4-nitrophenyl) phosphate molar ratio amounts to 12.5 : 1 for 2-iodosobenzoic acid and 6.25 : 1 for 3-iodoso-2-naphthoic acid.

scholarly journals Efficient reduction of methylene blue in aqueous solution using a Fenton-like catalyst of Fe3O4/Cu

2021 ◽  
Vol 947 (1) ◽  
pp. 012015
Author(s):  
Huynh-Vu-Thanh Luong ◽  
Huynh-Giao Dang ◽  
Phuong-Lan Tran-Nguyen ◽  
Diem-Trang Phan-Thi ◽  
Lam-Gia-Hao Dao
Keyword(s):  
Methylene Blue ◽  
Contact Time ◽  
Reaction Rate ◽  
Active Oxygen Species ◽  
Reaction Rate Constant ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Optimum Conditions ◽  
Efficient Reduction ◽  
Pseudo Second Order

Abstract This work aimed to investigate the efficient reduction of methylene blue (MB) by a heterogeneous magnetic nanoparticles/copper (MNs/Cu) Fenton-like catalyst. The MNs/Cu was successfully synthesized in the presence of Citrus aurantifolia extract. The characterizations showed an effective fabrication of Cu onto the surface of MNs. The reduction of MB by the MNs/Cu Fenton-like catalyst presented an efficiency of 99.5% at the optimum conditions, including MNs/Cu dose of 0.1 mg, temperature of 25°C, contact time of 75 min, pH 4.0, and 20 mL H2O2 30%, MB initial concentration of 25 mg/L. The reduction kinetics was well fitted to pseudo-second-order with reaction rate constant of 0.0029 g/mg.min. The main mechanism of the MB reduction due to active oxygen species was pointed out. The decrease of reduction yield at high pH, catalyst dose and MB concentration was elucidated in this study.

Assessment and Application of Modified Cationic Polyvinyl Alcohol Emulsifiers in Bitumen Emulsions

2021 ◽  
Vol 58 (6) ◽  
pp. 452-461
Author(s):  
Linlin Wang ◽  
Xiaoxi Wang ◽  
Runhan Hou ◽  
Qian Zhang ◽  
Yuexin Wang
Keyword(s):  
Polyvinyl Alcohol ◽  
Matrix Material ◽  
Molar Ratio ◽  
Ph Values ◽  
Positive Ions ◽  
Double Electron ◽  
Application Potential ◽  
Decreasing Ph ◽  
The Stability ◽  
Emulsions Stability

Abstract In this work, a series of emulsifiers were prepared by changing the molar ratio of polyvinyl alcohol (PVA) to the long chain quaternary ammonium salt (A0). The emulsifiers were characterised by FTIR and 1HNMR. The stability of the emulsions was checked and evaluated by determining the phase separation and by UV-Vis spectrophotometry. The emulsion stability increased with increasing emulsifier concentration, which was mainly due to the reduced droplet size and increased viscosity of the emulsions. Stability was also dependent on pH. At pH values between 5 to 3, stability was increased, but at further decreasing pH values, the emulsion became unstable or the emulsion separated. This could be mainly because the excess of positive ions compresses the double electron layer. The experimental results showed that PVA as a macromolecular matrix material has a great application potential for the emulsification process.

Characterization and functional properties of new everbearing strawberry (Fragaria x ananasa Duch.) cultivar, ‘Summertiara’ berries

2014 ◽  
Vol 4 (1) ◽  
pp. 1 ◽  
Author(s):  
Takeshi Nagai ◽  
Misuzu Tamai ◽  
Masato Sato ◽  
Yasuhiro Tanoue ◽  
Norihisa Kai ◽  
...  
Keyword(s):  
Vitamin C ◽  
Sensory Evaluation ◽  
Functional Properties ◽  
Active Oxygen Species ◽  
Active Oxygen ◽  
Antihypertensive Activity ◽  
Oxygen Species ◽  
Total Anthocyanins ◽  
Strawberry Cultivar ◽  
The Stability

Background: In recent years, a new everbearing strawberry cultivar, ‘Summertiara’ was cultivated to supply the strawberries in pre-harvest season from July to October in Japan. For highly research and development of processing of this cultivar, ‘Summertiara’ berries, the objective of this study was to characterize these berries, with relation to chemical parameters, total phenols, total flavonoids, total vitamin C, and total anthocyanins, and was to investigate the solubility and the stability of anthocyanins from the berries. Moreover, the functional properties such as antioxidative activity, active oxygen species scavenging activity, and antihypertensive activity were also evaluated.Methods: Chemical analysis, colour measurement, and sensory evaluation of new everbearing strawberry cultivar, ‘Summertiara’ berries were performed. Next, the solubility of anthocyanins from the berries and stability of these against pH, temperature, and an incandescent lighting were investigated. Moreover, functional properties of the extracts prepared from berries were elucidated using 5 different methods.Results: The contents of water, proteins, lipids, carbohydrates, and ash were the same as those of other cultivar berries. The sugar-acid ratio in the berries was low; these were acidulous. By sensory evaluation, the main factors were vivid red colour, aroma, and acidity. The berries were rich in phenols, flavonoids, vitamin C, and anthocyanins. The anthocyanins of the berries became unstable by heat treatment and light exposures such as visible rays. On the other hand, the extracts prepared from the berries showed the functionalities such as antioxidant activity, active oxygen species scavenging activities, and antihypertensive activity.  Conclusions: The strawberry cultivar, ‘Summertiara’ berries were the most suitable for processing ingredient of strawberry-derived products with superior health promoting functionalities.Keywords: Summertiara, everbearing strawberry cultivar, characterization, sensory evaluation, color and storage, functional property

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