scholarly journals Application of the redox system of Nocardia corallina B-276 in the enantioselective biotransformation of ketones and alcohols

2020 ◽  
Vol 85 (3) ◽  
pp. 279-290
Author(s):  
Alvarez Manjarrez ◽  
Méndez Pérez ◽  
Oba Solís ◽  
Cabello Ortega ◽  
Carvajal Lara ◽  
...  
Keyword(s):  
Reaction Time ◽  
Liquid Medium ◽  
Culture Media ◽  
Redox System ◽  
Enantioselective Reduction ◽  
Nocardia Corallina ◽  
Initial Ph

The aim of this research was to evaluate the redox system of Nocardia corallina B-276 in the biotransformation of 1-phenyl-1-propanone (1a), 2-hydroxy-1-phenylethanone (2a) and methyl (2-chlorophenyl)(oxo)acetate (3a) into 1-phenylpropan-1-ol (1b), 1-phenyl-1,2-ethanediol (2b) and methyl (2-chlorophenyl)(hydroxy)acetate (3b). The biomass of N. corallina was obtained in a liquid medium with an initial pH of 8.50, but the pH changed during the 96 h of the culture media, the final pH was between 4.74 and 7.62. The N. corallina biomass biocatalyzed the enantioselective reduction of 1a?3a to the corresponding alcohols. Whereas, during the process of oxidation of the rac-alcohols 1b?3b, 1b was oxidized in enantioselective way, the oxidation of 2b was not selective, but 3b was biotransformed mainly to (R)-3b. These results are indicative that N. corallina produced reductases and oxidases, whereby the biocatalytic activity was influenced by the final pH of the culture media, the reaction time and structure of the substrate.

Degradation of chlorpyriphos in water by advanced oxidation processes

2010 ◽  
Vol 10 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. Murillo ◽  
J. Sarasa ◽  
M. Lanao ◽  
J. L. Ovelleiro
Keyword(s):  
Reaction Time ◽  
Light Source ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
The Other ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
Oxidation Processes ◽  
Other Hand ◽  
Initial Ph

The degradation of chlorpyriphos by different advanced oxidation processes such as photo-Fenton, TiO2, TiO2/H2O2, O3 and O3/H2O2 was investigated. The photo-Fenton and TiO2 processes were optimized using a solar chamber as light source. The optimum dosages of the photo-Fenton treatment were: [H2O2]=0.01 M; [Fe3 + ]=10 mg l−1; initial pH = 3.5. With these optimum conditions total degradation was observed after 15 minutes of reaction time. The application of sunlight was also efficient as total degradation was achieved after 60 minutes. The optimum dosage using only TiO2 as catalyst was 1,000 mg l−1, obtaining the maximum degradation at 20 minutes of reaction time. On the other hand, the addition of 0.02 M of H2O2 to a lower dosage of TiO2 (10 mg l−1) provides the same degradation. The ozonation treatment achieved complete degradation at 30 minutes of reaction time. On the other hand, it was observed that the degradation was faster by adding H2O2 (H2O2/O3 molar ratio = 0.5). In this case, total degradation was observed after 20 minutes.

Effects of operational parameters on defluoridation efficiency using electrocoagulation process

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
M. Behbahani ◽  
M.R. Alavi Moghaddam ◽  
M. Arami
Keyword(s):  
Reaction Time ◽  
Anode Material ◽  
Removal Efficiency ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Operational Parameters ◽  
Applied Current ◽  
Initial Ph ◽  
Electrocoagulation Process ◽  
Electrode Connection

The aim of this study is to examine the effect of operational parameters on fluoride removal using electrocoagulation method. For this purpose, various operational parameters including initial pH, initial fluoride concentration, applied current, reaction time, electrode connection mode, anode material, electrolyte salt, electrolyte concentration, number of electrodes and interelectrode distance were investigated. The highest defluoridation efficiency achieved at initial pH 6. In the case of initial fluoride concentration, maximum removal efficiency (98.5%) obtained at concentration of 25mg/l. The increase of applied current and reaction time improved defluoridation efficiency up to 99%. The difference of fluoride removal efficiencies between monopolar and bipolar series and monopolar parallel were significant, especially at reaction time of 5 min. When aluminum used as anode material, higher removal efficiency (98.5%) achieved compared to that of iron anode (67.7%). The best electrolyte salt was NaCl with the maximum defluoridation efficiency of 98.5% compared to KNO3 and Na2SO4. The increase of NaCl had no effect on defluoridation efficiency. Number of electrodes had little effect on the amounts of Al3+ ions released in the solution and as a result defluoridation efficiency. Almost the same fluoride removal efficiency obtained for different interelectrode distances.

Influencing Factors of Chromium Ion Stability in Microbe Culture Media

2012 ◽  
Vol 610-613 ◽  
pp. 215-219
Author(s):  
Yun Xiao He ◽  
Xiao Ming Chen
Keyword(s):  
Ionic Liquid ◽  
Liquid Medium ◽  
Culture Media ◽  
Fluid Medium ◽  
Chromium Ion ◽  
Medium Components ◽  
Salt Ions ◽  
Ion Stability ◽  
The Stability ◽  
Ionic Liquid Medium

The stability factors for Cr6+ and Cr3+ in microbiological media, including temperature, preservation conditions and medium components were studied in this research project, through potassium permanganate oxidation and DPC (Diphenylcarbazide) spectrophotometry. It shows that the protein component mainly influences Cr6+ content changes at pre- and post- heat sterilization to the chromium ionic liquid medium, other than being impacted basically by inorganic salt ions. It also indicates that the method can be introduced into experiment researches for microbe dechromisation i.e. Chromium ion aqueous solution and fluid medium are sterilized separately, and then are made into the chrome ions liquid as per a certain concentration. The concentration of hexavalent chromium ions is affected by preservation time and temperature also. For this reason, chromium ionic liquid medium is kept at low temperature, and as quickly as possible for the test.

Study on Crosslinking in Diimide Reduction of Nitrile Butadiene Rubber

2006 ◽  
Vol 79 (4) ◽  
pp. 602-609
Author(s):  
Shuqin Zhou ◽  
Shaoyi Li ◽  
Huadong Bai
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Time ◽  
Boric Acid ◽  
Esr Spectroscopy ◽  
Redox System ◽  
Nitrile Group ◽  
Crosslinking Reaction ◽  
Butadiene Rubber ◽  
Drying Process ◽  
Spectroscopy Analysis

Abstract Acrylonitrile-butadiene rubber (NBR) in latex form was selectively hydrogenated by redox system consisting of hydrazine hydrate and hydrogen peroxide, with boric acid as catalyst. Soluble hydrogenated NBR latex was obtained; but the coagulated products were gelled on drying. This problem becomes the major obstacle for the hydrogenation technique to be commercialized. It is important to study the crosslinking reaction in the system and to solve the problem. The cause for the crosslink was investigated in three possibilities: (i) crosslinking caused by the hydrogenation of CN group; (ii) by the oxidation of C=C double bonds and (iii) by radicals in the system. The control of the crosslink was also studied. The oil resistant nitrile group —CN on the polymer chain had no change during drying process. There were no signs of carbonyl group C=O formed by oxidation and amine like groups -NH- formed by the hydrogenation of CN in HNBR gel fraction. The newly formed alkoxyl radicals were detected by ESR spectroscopy analysis in the hydrogenation system after specific reaction time. Crosslinking reaction was controlled to a large extent by using hydroquinone as gel inhibitor.

scholarly journals Photocatalytic Degradation of Naphthalene By UV/Zno: Kinetics, Influencing Factors and Mechanisms

2021 ◽  
Vol 37 (1) ◽  
pp. 65-70
Author(s):  
Aram Dokht Khatibi ◽  
Kethineni Chandrika ◽  
Ferdos Kord Mostafapour ◽  
Ali Akbar Sajadi ◽  
Davoud Balarak
Keyword(s):  
Wastewater Treatment ◽  
Reaction Time ◽  
Aqueous Solutions ◽  
Aromatic Hydrocarbons ◽  
Contact Time ◽  
Initial Concentration ◽  
Applied Study ◽  
Batch System ◽  
Initial Ph ◽  
Conventional Wastewater Treatment

Conventional wastewater treatment is not able to effectively remove Aromatic hydrocarbons such as Naphthalene, so it is important to remove the remaining antibiotics from the environment. The aim of this study was to evaluate the efficiency of UV/ZnOphotocatalytic process in removing naphthalene antibiotics from aqueous solutions.This was an experimental-applied study that was performed in a batch system on a laboratory scale. The variables studied in this study include the initial pH of the solution, the dose of ZnO, reaction time and initial concentration of Naphthalene were examined. The amount of naphthalene in the samples was measured using GC.The results showed that by decreasing the pH and decreasing the initial concentration of naphthalene and increasing the contact time, the efficiency of the process was developed. However, an increase in the dose of nanoparticles to 0.8 g/L had enhance the efficiency of the process was enhanced, while increasing its amount to values higher than 0.8 g/L has been associated with a decrease in removal efficiency.The results of this study showed that the use of UV/ZnOphotocatalytic process can be addressed as a well-organized method to remove naphthalene from aqueous solutions.

scholarly journals Application of a Continuous Bipolar Mode Electrocoagulation (CBME) system for polishing distillery wastewater

2019 ◽  
Vol 93 ◽  
pp. 02005 ◽  
Author(s):  
Madhuri Damaraju ◽  
Debraj Bhattacharyya ◽  
Tarun Panda ◽  
Kiran Kumar Kurilla
Keyword(s):  
Reaction Time ◽  
Current Density ◽  
Optimal Point ◽  
Suitable Alternative ◽  
Toc Removal ◽  
Bipolar Mode ◽  
Recalcitrant Carbon ◽  
Initial Ph ◽  
Distillery Wastewater ◽  
Experimental Values

A continuous bipolar mode electrocoagulation (CBME) unit was used in this study for polishing a biologically treated distillery wastewater at laboratory scale. This study focuses on optimizing the process for removal of Total Organic Carbon (TOC) from an anaerobically-treated distillery wastewater. Response surface methodology (RSM) was used for optimizing the process. The study was conducted by varying three operating parameters: Initial pH (2-10), reaction time (0.5-15 min), and current density (13-40 A/sqm). High R-square values, above 0.9, were obtained with ANOVA. Optimal point was observed to be at pH-6.04, Reaction time-11.63 min, current density-39.2 A/sqm. Experimental values of TOC removal at optimal point were found to be 73% against maximum predicted value of 79%. Color removal efficiency was observed to be 85% at the optimal points. It can be concluded that CBME system can be a suitable alternative for removal of recalcitrant carbon and color post-biological treatment in distillery wastewaters.

scholarly journals Characterization and Antioxidant Activity of Products Derived from Xylose–Bovine Casein Hydrolysate Maillard Reaction: Impact of Reaction Time

Foods ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 242 ◽  
Author(s):  
Kun Chen ◽  
Jiajia Zhao ◽  
Xiaohan Shi ◽  
Qayum Abdul ◽  
Zhanmei Jiang
Keyword(s):  
Antioxidant Activity ◽  
Reaction Time ◽  
Maillard Reaction ◽  
Radical Scavenging ◽  
Casein Hydrolysate ◽  
Size Exclusion ◽  
Maillard Reaction Products ◽  
Reaction Products ◽  
Exclusion Chromatography ◽  
Initial Ph

The characterization and antioxidant activity on Maillard reaction products (MRPs) derived from xylose and bovine casein hydrolysate (BCH) was investigated at 100 °C and initial pH 8.0 as a function of reaction time. The pH values and free amino groups contents of xylose–BCH MRPs remarkably decreased with the reaction time up to 8 h, whereas their browning intensities significantly increased (p < 0.05). After 4 h of heat treatment, the fluorescence properties of xylose–BCH MRPs reached the maximum. There was a production of higher and smaller molecular substances in xylose–BCH MRPs with an increased reaction time, as analyzed by size exclusion chromatography. The 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical scavenging capacity and ferrous reducing activity of xylose-BCH MRPs gradually increased with the reaction time extended from 0 to 8 h.

Synergetic Degradation of Zidovudine Wastewater by Ultrasonic and Iron-Carbon Micro-Electrolysis

2011 ◽  
Vol 347-353 ◽  
pp. 1949-1952 ◽  
Author(s):  
Liang Li ◽  
Bing Zhe Xu ◽  
Chang Yu Lin ◽  
Xiao Min Hu
Keyword(s):  
Reaction Time ◽  
Degradation Rate ◽  
Removal Rate ◽  
Cod Removal ◽  
Mass Ratio ◽  
Initial Ph ◽  
Cod Removal Rate

Zidovudine wastewater is difficult to biodegradation due to high COD and toxicity. The synergetic treatment of Zidovudine wastewater by Ultrasonic and iron-carbon micro-electrolysis technology was studied. The influence of initial pH, reaction time, mass ratio of iron and carbon and mass ratio of iron and water on degradation rate of COD was researched. The result showed that the COD removal rate was only about 54.3% and the degradation speed is very slow when iron-carbon micro-electrolysis treated Zidovudine wastewater　separately. However, when ultrasonic synergy micro-electrolysis to treat Zidovudine wastewater, the COD removal rate could was up to 85% and the reaction time was also decreased. Moreover, the BOD5 / COD rose from 0.15 to 0.35, which meant the wastewater became easily biodegradable.

scholarly journals Temporary immersion biorreators: efficient technique for the propagation of the ‘Pircinque’ strawberry

2019 ◽  
Vol 41 (1) ◽  
Author(s):  
Samila Silva Camargo ◽  
Leo Rufato ◽  
Maicon Magro ◽  
André Luiz Kulkamp de Souza
Keyword(s):  
Liquid Medium ◽  
Culture Medium ◽  
Culture Media ◽  
Time Factors ◽  
Efficient Technique ◽  
Control Treatment ◽  
Solid Culture ◽  
Temporary Immersion ◽  
Solid Culture Medium

Abstract The in vitro propagation technique via temporary immersion bioreactors is a tool that, through the culture in a liquid medium, allows an increase in the efficiency of seedling production. Several researches with the strawberry crop have shown greater efficiency of the system compared to the conventional process of micropropagation in solid medium. In this sense, the objective herein was to establish a protocol of multiplication and rooting of the ‘Pircinque’ strawberry, in temporary immersion bioreactors. Two distinct and independent studies were carried out, characterized by the multiplication and rooting stages of strawberry explants, newly introduced and registered in Brazil. Two culture media (MS and KNOP) were studied and, as a control treatment, the growth of the explants in solid culture medium was evaluated with the addition of 5 g L-1 of agar. Different immersion times of the culture medium were explored: five or eight times a day, for 15 minutes. The study was composed of the culture medium and immersion time factors, as well as the control (solid) treatment. It was verified that the use of temporary immersion bioreactors system is an efficient technique for the multiplication and rooting of explants of strawberry cv. Pircinque, when compared to the conventional method of micropropagation with the use of solid culture medium, making it possible to optimize the production of seedlings in biofactories. The MS liquid medium, in contact with explants of ‘Pircinque’ strawberry five times a day, increased the growth of the aerial part and the root system.

scholarly journals Influence of medium composition and pH on the production of polygalacturonases by Aspergillus oryzae

2004 ◽  
Vol 47 (5) ◽  
pp. 693-702 ◽  
Author(s):  
Eloane Malvessi ◽  
Mauricio Moura da Silveira
Keyword(s):  
Liquid Medium ◽  
Aspergillus Oryzae ◽  
Wheat Bran ◽  
Medium Composition ◽  
Citrus Fruits ◽  
A Value ◽  
Initial Ph ◽  
Normal Increase

A liquid medium containing wheat bran, salts and a source of inducer (pectin) was found to be suitable for the production of exo- and endo-polygalacturonases by Aspergillus oryzae CCT3940. Induction of polygalacturonases by purified pectin was significantly higher than when rinds of citrus fruits were used as inducer. A. oryzae growth was favoured by pH close to 4, although a drop of pH to around 3 was needed for enzymes production. Afterwards, decreasing activities were observed with the normal increase in pH to near neutrality. The highest activities were achieved with an initial pH of 4 and controlled when it decreased to a value slightly below 3 (159 units endo-PG.mL-1 at 83 h and 45 units exo-PG.mL-1 at 64 h), being the loss in polygalacturonases activities strongly reduced at this condition. The best values of pH and temperature for the action of exo-PG (4.5/57ºC) and endo-PG (4.3/40ºC) were assessed.

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