Photodegradation of p-Nitrophenol Catalyzed by ZnO/MWCNTs Composite Catalyst in Water

2012 ◽  
Vol 455-456 ◽  
pp. 1339-1344 ◽  
Author(s):  
Zhe Qi Li ◽  
Jing Yu Liu
Keyword(s):  
Irradiation Time ◽  
Solar Irradiation ◽  
Composite Catalyst ◽  
Catalyst Loading ◽  
Optimal Conditions ◽  
Mass Ratio ◽  
Initial Substrate ◽  
Effects Of Ph ◽  
Potential Use ◽  
Initial Substrate Concentration

Photodegradation ofp-nitrophenol catalyzed by ZnO/MWCNTs composite in water was investigated. The effects of pH, irradiation time, catalyst loading, initial substrate concentration and MWCNTs content on the degradation were investigated. Experiment results revealed that the optimal conditions were ap-nitrophenol concentration of 60.0 mg/L at pH 5.0 with catalyst loading of 10.0 g/L under solar irradiation for the illumination of 180 min. The highest efficiency on photodegradation ofp-nitrophenol can be achieved with an optimal MWCNTs/ZnO mass ratio of 0.16%. Possible decomposing mechanisms were also discussed. The repeatability of photocatalytic activity was tested. The photocatalyst was used ten cycles with degradation efficiency still higher than 95%. The results of the study showed the feasible and potential use of ZnO/MWCNTs composite in degradation of toxic organic pollutants.

Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents

2013 ◽  
Vol 67 (6) ◽  
pp. 1260-1271 ◽  
Author(s):  
I. Michael ◽  
E. Hapeshi ◽  
C. Michael ◽  
D. Fatta-Kassinos
Keyword(s):  
Advanced Oxidation Process ◽  
Oxidation Process ◽  
Heterogeneous Photocatalysis ◽  
Solar Irradiation ◽  
Fenton Process ◽  
Iron Salt ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Initial Substrate ◽  
Initial Substrate Concentration

The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe2+/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe2+ and H2O2 for homogeneous ([Fe2+] = 5 mg L−1, [H2O2] = 3.062 mmol L−1) and TiO2 ([TiO2] = 3 g L−1) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir–Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ∼70% degradation of TMP within 120 min of treatment and 13% DOC removal.

scholarly journals Statistical Optimization of Operational Parameters for Enhanced Naphthalene Degradation by Photocatalyst

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Aijuan Zhou ◽  
Jing Peng ◽  
Zhaobo Chen ◽  
Jingwen Du ◽  
Zechong Guo ◽  
...  
Keyword(s):  
Degradation Rate ◽  
Design Method ◽  
Irradiation Time ◽  
Catalyst Loading ◽  
Statistical Experimental Design ◽  
Optimal Conditions ◽  
Operational Parameters ◽  
Excellent Correlation ◽  
Naphthalene Degradation ◽  
Central Composite

The optimization of operational parameters for enhanced naphthalene degradation by TiO2/Fe3O4-SiO2(TFS) photocatalyst was conducted using statistical experimental design and analysis. Central composite design method of response surface methodology (RSM) was adopted to investigate the optimum value of the selected factors for achieving maximum naphthalene degradation. Experimental results showed that irradiation time, pH, and TFS photocatalyst loading had significant influence on naphthalene degradation and the maximum degradation rate of 97.39% was predicted when the operational parameters were irradiation time 97.1 min, pH 2.1, and catalyst loading 0.962 g/L, respectively. The results were further verified by repeated experiments under optimal conditions. The excellent correlation between predicted and measured values further confirmed the validity and practicability of this statistical optimum strategy.

scholarly journals Modeling gallic acid production rate by empirical and statistical analysis

2000 ◽  
Vol 43 (5) ◽  
pp. 509-513 ◽  
Author(s):  
Bratati Kar ◽  
Rintu Banerjee ◽  
Bimal Chandra Bhattacharyya
Keyword(s):  
Statistical Analysis ◽  
Gallic Acid ◽  
Acid Production ◽  
Maximum Rate ◽  
Enzymatic Reaction ◽  
Enzyme Concentration ◽  
Operating Conditions ◽  
Optimal Conditions ◽  
Initial Substrate ◽  
Initial Substrate Concentration

For predicting the rate of enzymatic reaction empirical correlation based on the experimental results obtained under various operating conditions have been developed. Models represent both the activation as well as deactivation conditions of enzymatic hydrolysis and the results have been analyzed by analysis of variance (ANOVA). The tannase activity was found maximum at incubation time 5 min, reaction temperature 40ºC, pH 4.0, initial enzyme concentration 0.12 v/v, initial substrate concentration 0.42 mg/ml, ionic strength 0.2 M and under these optimal conditions, the maximum rate of gallic acid production was 33.49 mumoles/ml/min.

scholarly journals OXIDATION OF ORGANIC COMPOUNDS BY MAGNETIC BIOCATALYST

2020 ◽  
pp. 31-39
Author(s):  
Ольга Валентиновна Гребенникова ◽  
Александрина Михайловна Сульман ◽  
Степан Петрович Михайлов ◽  
Елена Игоревна Шиманская ◽  
Валентина Геннадьевна Матвеева
Keyword(s):  
Hydrogen Peroxide ◽  
Vitamin E ◽  
Magnetic Nanoparticles ◽  
Organic Compounds ◽  
Substrate Concentration ◽  
Oxidation Reaction ◽  
Optimal Conditions ◽  
Initial Substrate ◽  
Oxidation Of Organic Compounds ◽  
Initial Substrate Concentration

В статье описывается синтез магнитного биокатализатора на основе иммобилизованной пероксидазы. Данный биокатализатор тестировался в реакции окисления 2,3,6-триметилфенола с помощью пероксида водорода до 2,3,5-триметилгидрохинона (полупродукта витамина Е). В работе выбран метод синтеза магнитных наночастиц. Подобраны оптимальные условия проведения процесса окисления 2,3,6-триметилфенола в присутствии магнитного биокатализатора (начальная концентрация субстрата, температура, рН). The article describes the synthesis of a magnetic biocatalyst based on immobilized peroxidase. This biocatalyst was tested in the oxidation reaction of 2,3,6-trimethylphenol with hydrogen peroxide to 2,3,5-trimethylhydroquinone (an intermediate of vitamin E). In the work, the method of synthesis of magnetic nanoparticles is selected.The optimal conditions for the process of oxidation of 2,3,6-trimethylphenol in the presence of a magnetic bio-catalyst are selected (initial substrate concentration, temperature, pH).

scholarly journals Photocatalytic degradation of thiotriazinone, stable hydrolysis product of antibiotic ceftriaxone

2019 ◽  
pp. 1-11
Author(s):  
Biljana Abramovic ◽  
Maria Uzelac ◽  
Nina Fincur
Keyword(s):  
Photocatalytic Degradation ◽  
Electron Acceptor ◽  
Hydrolysis Product ◽  
Ammonium Persulfate ◽  
Solar Irradiation ◽  
Catalyst Loading ◽  
Optimal Conditions ◽  
Kinetics Of Degradation ◽  
Simulated Solar Irradiation ◽  
Kinetics Of

In this work, the efficiency of direct photolytic and photocatalytic degradation of thiotriazinone, stable hydrolysis product of antibiotic ceftriaxone, was examined. The efficiency of photocatalytic degradation of 0.05 mmol/dm3 thiotriazinone solution was investigated using commercially available TiO2 Hombikat catalyst under simulated solar irradiation, as well as in the absence/presence of ammonium persulfate ((NH4)2S2O8) as electron acceptor. It was found that the optimal conditions for photocatalytic degradation of thiotriazinone were: catalyst loading 1.0 mg/cm3 of TiO2 Hombikat, electron acceptor 3 mmol/dm3 of (NH4)2S2O8 solution, and pH 7.6. Under the stated conditions 76.0% of thiotriazinone was degradated after 60 min of irradiation. The kinetics of degradation was followed by UFLC-DAD technique.

scholarly journals Straightforward Synthesis of Mn3O4/ZnO/Eu2O3-Based Ternary Heterostructure Nano-Photocatalyst and Its Application for the Photodegradation of Methyl Orange and Methylene Blue Dyes

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4661
Author(s):  
Jayachamarajapura Pranesh Shubha ◽  
Haralahalli Shivappa Savitha ◽  
Syed Farooq Adil ◽  
Mujeeb Khan ◽  
Mohammad Rafe Hatshan ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Methyl Orange ◽  
Irradiation Time ◽  
Solar Irradiation ◽  
Anionic Dyes ◽  
One Pot ◽  
Sunlight Irradiation ◽  
Ft Ir ◽  
Degradation Activity ◽  
Ecological Applications

Zinc oxide-ternary heterostructure Mn3O4/ZnO/Eu2O3 nanocomposites were successfully prepared via waste curd as fuel by a facile one-pot combustion procedure. The fabricated heterostructures were characterized utilizing XRD, UV–Visible, FT-IR, FE-SEM, HRTEM and EDX analysis. The photocatalytic degradation efficacy of the synthesized ternary nanocomposite was evaluated utilizing model organic pollutants of methylene blue (MB) and methyl orange (MO) in water as examples of cationic dyes and anionic dyes, respectively, under natural solar irradiation. The effect of various experimental factors, viz. the effect of a light source, catalyst dosage, irradiation time, pH of dye solution and dye concentration on the photodegradation activity, was systematically studied. The ternary Mn3O4/ZnO/Eu2O3 photocatalyst exhibited excellent MB and MO degradation activity of 98% and 96%, respectively, at 150 min under natural sunlight irradiation. Experiments further conclude that the fabricated nanocomposite exhibits pH-dependent photocatalytic efficacy, and for best results, concentrations of dye and catalysts have to be maintained in a specific range. The prepared photocatalysts are exemplary and could be employed for wastewater handling and several ecological applications.

Microwave-Assisted Extraction of Chlorophyll from Filter Mud of Sugercane Mill and Component Analysis

2012 ◽  
Vol 518-523 ◽  
pp. 430-435 ◽  
Author(s):  
Hai Rong Guo ◽  
Shao Ying Ma ◽  
Xiao Fei Wang ◽  
Er Fang Ren ◽  
Yuan Yuan Li
Keyword(s):  
Irradiation Time ◽  
Extraction Time ◽  
Extraction Temperature ◽  
Microwave Assisted Extraction ◽  
Optimal Conditions ◽  
Microwave Assisted ◽  
Assisted Extraction ◽  
Conventional Extraction ◽  
Filter Mud ◽  
Strong Absorption Peak

Microwave-assisted extraction (MAE) was used to extract chlorophylls from filter mud. Ethanol was used as the solvent. The optimal conditions for the MAE of chlorophylls were concluded from the study as the irradiation time, 50 s, the ratio of liquid to solid, 8:1 (mL/g), the extraction temperature, 40 °C, and the extraction time, 60 min. Compared with conventional extraction, the MAE of chlorophylls from the filter mud was more effective. The extraction time for MAE was 60 min with 0.277 mg/g chlorophyll yield, while conventional extraction needed 240 min with only about 0.259 mg/g chlorophyll yield. The Ultraviolet Absorption Spectra of the extracted chlorophylls showed that there was a strong absorption peak at about 663 nm. C=N, Mg-N and C-N was not seen existed from the infrared spectroscopy probably because that the mixed extracts were not purified and the chlorophyll content was less.

The Physiology of Sea-Urchin Spermatozoa

1950 ◽  
Vol 26 (4) ◽  
pp. 396-409
Author(s):  
LORD ROTHSCHILD
Keyword(s):  
Sea Urchin ◽  
Seminal Plasma ◽  
Human Blood ◽  
Phosphate Buffer ◽  
Dry Weight ◽  
O2 Uptake ◽  
Low Concentrations ◽  
Initial Substrate ◽  
Rough Calculation ◽  
Initial Substrate Concentration

1. Spermatozoa and seminal plasma of Echinus esculentus contain catalase. 2. At 15° C., 4 ml. of a suspension of semen diluted with neutral phosphate buffer in the ratio 1:13 produced in 1 min. 90µl. O2 from an H2O2 solution containing 150 µl. O2. The dry weight of semen in the suspension was 45 mg. and the number of spermatozoa 8.55x109. Under the same conditions, seminal plasma obtained by centrifuging semen produced 50 µl. O2 in 1 min. The dry weight of seminal plasma in the suspension was 12 mg. Human blood, dry weight 229.3 mg./ml., must be diluted with phosphate buffer in the ratio 1:1700 to produce the same amount of O2 in 1 min. as the above suspension of semen. If catalatic activity is defined by the equation Ac = (gt)-1 In {a/(a-x)}, where g = weight in g./ml. of the catalase-containing material, t = 1 min., a = initial substrate concentration (H2O2), and x = amount of H2O2 decomposed in 1 min. at 15° C., Ac = 80-100, 150-200 and 6800 respectively for sea-urchin semen, sea-urchin seminal plasma and human blood. 3. The catalatic activity of semen and seminal plasma is strongly inhibited by hydroxylamine. 4. The O2 uptake and motility of sea-urchin spermatozoa is unaffected by M/5000 H2O2. Higher concentrations of H2O2, M/3000-5000, produce a pronounced ‘shock’ effect, from which the spermatozoa often completely recover. 5. Low concentrations of hydroxylamine, M/3000, reduce O2 uptake and motility. 6. Sea-urchin spermatozoa are almost instantly killed by combinations of hydroxylamine and H2O2, at concentrations which are relatively innocuous when the substances are added separately. 7. A rough calculation indicates that a single spermatozoon contains less than 500 molecules of catalase. 8. A new method of adding H2O2 to catalase-containing material in a manometer is described.

scholarly journals Extraction of Phytosterol Concentration in Different Legume Pods by Using Microwave-Assisted Hydrodistillation

2019 ◽  
Vol 19 (3) ◽  
pp. 796
Author(s):  
Noormazlinah Noormazlinah ◽  
Norlaili Hashim ◽  
Abdurahman Hamid Nour ◽  
Mimi Sakinah Abdul Munaim ◽  
Maria Pilar Almajano ◽  
...  
Keyword(s):  
Bioactive Compounds ◽  
Microwave Power ◽  
Ethanol Concentration ◽  
Irradiation Time ◽  
Optimal Conditions ◽  
Solvent Concentration ◽  
Visible Spectroscopy ◽  
Optimum System ◽  
Microwave Assisted ◽  
Extraction Parameters

The traditional ways in the extraction of bioactive compounds using conventional methods are disadvantageous from both economic and environmental perspectives. In this, the potential of microwave-assisted hydrodistillation conditions for extraction of phytosterol from legume pods was investigated. Salkowski test performed on the legume pod has shown the reddish brown in all sample which confirmed the presence of phytosterol qualitatively. Liebermann-Burchard procedure and ultraviolet-visible spectroscopy (UV-Vis) apparatus were used to study the concentration of phytosterol at different extraction parameters which are temperature (25–80 °C), solvent concentration (50–100% v/v), irradiation time (1–10 min) and microwave power (400–800 W). The optimal conditions for highest yield of extract (0.219 mg/L) were obtained at a microwave power of 600 W, the irradiation time of 6 min, and ethanol concentration of 75% v/v. Results obtained in this study have shown the capability of microwave-assisted hydrodistillation in the extraction of phytosterol from legume pod. Further works are nevertheless required to provide a deeper understanding of the mechanisms involved to facilitate the development of an optimum system applicable to the industry.

scholarly journals Formation of conjugated double bonds in soybean oil with iodine as a catalyst

2016 ◽  
Vol 81 (2) ◽  
pp. 141-151 ◽  
Author(s):  
Jie Yan ◽  
Jinlan Yang ◽  
Rifu Yang ◽  
Haifen He ◽  
Qihai Liu ◽  
...  
Keyword(s):  
Linoleic Acid ◽  
Reaction Time ◽  
Soybean Oil ◽  
Linolenic Acid ◽  
Conversion Rate ◽  
Raw Material ◽  
Catalyst Loading ◽  
Optimal Conditions ◽  
Trans Isomers ◽  
High Conversion Rate

A method for the iodine-catalyzed conjugation of soybean oil was developed, and the conjugated product was analyzed by UV, IR, and 1H NMR. The results indicated that the optimal conditions for conjugation included a temperature of 180?C, a catalyst loading of 0.5 wt.% and a reaction time of 3 h, at which the concentration of conjugated linoleic acid was 1.51 mol L-1, with 92 % conversion, the CLNA reached 0.225 mol L-1 when the temperature was 130?C, a catalyst loading of 0.5 wt.%, and a reaction time of 3 h with a conversion rate of 99.9 %. The reaction predominantly produced trans-trans, trans-cis and cis-trans isomers. It was also revealed that the conjugation of linolenic acid was much faster than that of linoleic acid. The method possessed the advantages of a short procedure, a high conversion rate, and no methyl esterification of the raw material, and it was an environmentally friendly technology that does not use solvents.

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