scholarly journals Phase Transformation of VO2Nanoparticles Assisted by Microwave Heating

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Phatcharee Phoempoon ◽  
Lek. Sikong
Keyword(s):  
Microwave Power ◽  
Irradiation Time ◽  
Power Level ◽  
Thermal Analyses ◽  
Morphological Properties ◽  
Microwave Assisted Synthesis ◽  
Tem Analysis ◽  
Microwave Assisted ◽  
Thermochromic Properties ◽  
Microwave Power Level

The microwave assisted synthesis nowadays attracts a great deal of attention. Monoclinic phase VO2(M) was prepared from NH4VO3andH2C2O4·2H2Oby a rapid microwave assisted technique. The synthesis parameters, microwave irradiation time, microwave power, and calcinations temperature were systematically varied and their influences on the structure and morphology were evaluated. The microwave power level has been carried out in range 180–600 W. TEM analysis demonstrated nanosized samples. The structural and morphological properties were measured using XRD, TEM, and thermal analyses. The variations of vanadium phase led to thermochromic properties.

scholarly journals Screening of Microwave-Assisted-Batch Extraction Parameters for Recovering Total Phenolic and Flavonoid Contents from Chromolaena odorata Leaves through Two-Level Factorial Design

2019 ◽  
Vol 19 (2) ◽  
pp. 511 ◽  
Author(s):  
Oluwaseun Ruth Alara ◽  
Abdurahman Hamid Nour ◽  
Siti Kholijah Binti Abdul Mudalip
Keyword(s):  
Factorial Design ◽  
Microwave Power ◽  
Ethanol Concentration ◽  
Irradiation Time ◽  
Power Level ◽  
Feed Ratio ◽  
Total Phenolic ◽  
Chromolaena Odorata ◽  
Microwave Assisted ◽  
Microwave Power Level

Microwave-assisted extraction (MAE) of phenolic compounds from Chromolaena odorata leaves was investigated using one-factor-at-a-time (OFAT) and two-level factorial design. The MAE parameters studied were irradiation time (A: 1–5 min); microwave power level (B: 400-800 W); extraction temperature (C: 60–80 °C); solvent/feed ratio (D: 8:1–14:1 mL/g); and ethanol concentration (E: 20–60% v/v). The optima yields of TPC and TFC were 56.13 mg GAE/g d.w. and 44.78 mg QE/g d.w., respectively were achieved from MAE of C. odorata leaf at irradiation time of 2 min, microwave power of 600 W, temperature of 60 °C, solvent:feed ratio of 10:1 mL/g, and ethanol concentration of 40% v/v through one-factor-at-time (OFAT) experimental trials. The results obtained from a two-level factorial design experiments reflected that only ethanol concentration (20–60% v/v), irradiation time (1–5 min) and microwave power level (400–800 W) had significant effects on the yields of total phenolic content (TPC) and total flavonoid content (TFC) from C. odorata leaves (p < 0.05). However, temperature and solvent/feed ratio was not significant. In addition, the interactions AB (irradiation time and microwave power) and AE (irradiation time and ethanol concentration) contributed greatly to the recovery yields.

MICROWAVE ASSISTED PYROLYSIS (MAP) OF AUTOMOTIVE PAINT SLUDGE (APS)

2015 ◽  
Vol 75 (8) ◽  
Author(s):  
Zakiuddin Januri ◽  
Norazah Abdul Rahman ◽  
Siti Shawalliah Idris ◽  
Sharmeela Matali ◽  
Shareena Fairuz Abdul Manaf
Keyword(s):  
Microwave Power ◽  
Power Level ◽  
Liquid Product ◽  
Sample Weight ◽  
Microwave Assisted ◽  
Automotive Paint ◽  
Paint Sludge ◽  
Microwave Power Level ◽  
Radiation Time ◽  
Weight Loading

Hazardous waste such as automotive paint sludge has a potential to be recovered or treated with advance method such as microwave assisted pyrolysis. It is an advantage for the process with the aid of microwave radiation to the system due to the high affinity of water in the automotive paint sludge which acts as the medium of heating in the microwave pyrolysis reaction. By having such process, not only it is good to dispose the automotive paint sludge but three different products have been recovered from that process such as solid char, liquid oil and gas. With the high hydrocarbon content in the automotive paint sludge, it was estimated that high valuable hydrocarbon might be recovered in the liquid product. From this research, three parameters were studied and analyzed for the product distribution and liquid oil recovered which are sample weight loading, microwave power level and radiation time. It was observed that best sample weight loading, microwave power level and radiation time to produce high liquid hydrocarbon oil were 200g, 1000W and 30 minutes respectively in which 0.1g or 0.27% was liquid oil recovered from overall sample weight loading. 

scholarly journals Application of Plackett Burman Design for Antioxidant Extraction from Actinodaphne sesquipedalis leaves

2019 ◽  
Vol 8 (6S3) ◽  
pp. 48-51
Keyword(s):  
Microwave Power ◽  
Ethanol Concentration ◽  
Irradiation Time ◽  
Radical Scavenging Activity ◽  
Power Level ◽  
Radical Scavenging ◽  
Solvent Ratio ◽  
Burman Design ◽  
Plackett Burman Design ◽  
Microwave Power Level

Actinodaphne sesquipedalis Hook. F. Var. Glabra (Kochummen), also known as “Medang payung” by the Malay people, belongs to the Lauraceae family. In this study, a Plackett-Burman design was used to evaluate the significant extraction parameters in achieving maximum DPPH radical scavenging activity from ethanol leaves extract of A. sesquipedalis. Microwave-assisted extraction technique was employed using aqueous ethanol. The independent parameters were microwave power level (30–60 W), feed-to-solvent ratio (1:30 g/ml), irradiation time (30-90 s) and ethanol concentration (20–80%). Amongst the examined parameters, ethanol concentration, microwave power level, and irradiation/extraction time were significant, whereas, feed-to-solvent ratio was insignificant. Therefore, antioxidants from the ethanolic extraction leaves of A. sesquipedalis using microwave technique are significantly affected by ethanol concentration, irradiation time and microwave power.

scholarly journals Microwave-Assisted Synthesis of Isopropylβ-(3,4-Dihydroxyphenyl)-α-hydroxypropanoate

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Qun-Zheng Zhang ◽  
Xue-Feng Tian ◽  
Guan-Le Du ◽  
Qing Pan ◽  
Yi Wang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Microwave Heating ◽  
Orthogonal Design ◽  
Power Level ◽  
Conventional Heating ◽  
Microwave Assisted Synthesis ◽  
Reaction Conditions ◽  
Microwave Assisted ◽  
Clemmensen Reduction ◽  
Microwave Power Level

Using microwave irradiation heating, isopropylβ-(3,4-dihydroxyphenyl)-α-hydroxypropanoate was synthesised from 3,4-dihydroxybenzaldehyde and acetylglycine through the formation of 2-methyl-4-(3,4-acetoxybenzylene)oxazol-5-ones,α-acetylamino-β-(3,4-diacetoxyphenyl)acrylic acid, andβ-(3,4-dihydroxyphenyl)pyruvic acid followed by Clemmensen reduction and esterification. The reaction conditions in terms of operating parameters were optimised by using an orthogonal design of experiment (ODOE) approach, including reaction temperature, reaction time, and microwave power level. Compared with conventional heating, the reaction time was significantly reduced for all reactions and the product yields were increased (except for the third-step reaction) under microwave heating conditions. The most remarkable microwave enhancement was found in the step of isopropylβ-(3,4-dihydroxyphenyl)-α-hydroxypropanoate production where the reaction time was reduced from 10 hrs (conventional heating) to 25 mins (microwave heating) whilst the yield was increased from 75.6% to 87.1%, respectively.

Study of color kinetics of banana (Musa cavendish) under microwave drying by application of image analysis

2020 ◽  
pp. 108201322098133
Author(s):  
Sagar Nagvanshi ◽  
Subbarao Kotra Venkata ◽  
TK Goswami
Keyword(s):  
Microwave Power ◽  
Vision System ◽  
Power Level ◽  
Microwave Drying ◽  
Slice Thickness ◽  
Order Kinetic ◽  
Drying Time ◽  
Volumetric Heating ◽  
Kinetics Of ◽  
Microwave Power Level

Microwave drying works on the volumetric heating concept promoted by electromagnetic radiation at 0.915 or 2.450 GHz. In this study, banana ( Musa Cavendish) was taken as the sample and treated under microwave drying. The effect of two process variables, namely slice thickness (2, 3.5, and 5 mm) and microwave power (180 W, 360 W, and 540 W), were studied on drying kinetics and color kinetics. It was observed that the inverse variation relationship exists between drying time and microwave power level while drying time and slice thickness exhibited a direct variation relationship. A Computer Vision System (CVS) was developed to measure the color values of banana in CIELab space using an algorithm written in MATLAB software. Once the color parameters were obtained, they were fitted in First and Zero-order kinetic models. Both models were found to describe the color values adequately. This study concludes that microwave drying is a promising dehydration technique for banana drying that reduces the significant time of drying. Application of CVS is an excellent approach to measure the surface color of banana.

scholarly journals Microwave-assisted synthesis and characterization of some optically active poly(ester-imide) thermoplastic elastomers

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Saeed Zahmatkesh ◽  
Abdol Reza Hajipour
Keyword(s):  
Thermal Analyses ◽  
Specific Rotation ◽  
Thermoplastic Elastomers ◽  
Optically Active ◽  
Microwave Assisted Synthesis ◽  
H Nmr ◽  
Microwave Assisted ◽  
Diacid Chloride ◽  
Elemental Analyses

AbstractPyromellitic dianhydride (1) was reacted with L-leucine (2) to result in [N,N'-(pyromellitoyl)-bis-L-leucine diacid] (3). This compound (3) was converted to N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride (4) by reaction with thionyl chloride. The microwave-assisted polycondensation of this diacid chloride (4) with polyethyleneglycol-diol (PEG-200) and/or three synthetic bisphenols furnish a series of new PEIs and Co-PEIs in a laboratory microwave oven (Milestone). The resulting polymers and copolymers have inherent viscosities in the range of 0.31- 0.53 dl g-1. These polymers are optically active, thermally stable and soluble in polar aprotic solvents such as DMF, DMSO, NMP, DMAc and sulfuric acid. All of the above polymers were fully characterized by IR spectroscopy, 1H NMR spectroscopy, elemental analyses, specific rotation and thermal analyses. Some structural characterizations and physical properties of these optically active PEIs and Co-PEIs are reported.

Microwave Assisted Synthesis of Schiff Bases: A Green Approach

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Mousumi Chakraborty ◽  
Sanjay Baweja ◽  
Sunita Bhagat ◽  
TejpalSingh Chundawat
Keyword(s):  
Microwave Irradiation ◽  
Microwave Power ◽  
Mass Spectra ◽  
Molar Ratio ◽  
Microwave Assisted Synthesis ◽  
Schiff’S Bases ◽  
Microwave Assisted ◽  
Green Approach ◽  
Schiff's Bases ◽  
Effects Of Temperature

Abstract In the present study Schiff’s bases are synthesized by the conventional as well as by microwave irradiation. Excellent yield within short reaction time is obtained using microwave irradiation along with other advantages like mild reaction condition, non-hazardous and safer environmental conditions. The effects of temperature, reactant molar ratio, and microwave power variation on yield are observed. Mathematical model has been developed using matlab software to obtain the yield as a function of microwave power. Kinetic study of the reaction has also been attempted. Schiff’s bases structures are confirmed by IR, 1HNMR, Mass Spectra and elemental analysis.

Microwave-Irradiated Preparation of Super Absorbent Resin by Graft Copolymerization of Starch and Acrylic Acid

2011 ◽  
Vol 291-294 ◽  
pp. 1335-1338
Author(s):  
Da Biao Zhao
Keyword(s):  
Acrylic Acid ◽  
Microwave Irradiation ◽  
Graft Copolymerization ◽  
Irradiation Time ◽  
Low Cost ◽  
Power Level ◽  
Conventional Heating ◽  
Simple Process ◽  
One Step ◽  
Microwave Power Level

Graft copolymerization of acrylic acid(AA) on starch to prepare super absorbent resin (SAR) under microwave irradiation were investigated using N,N-methylene bis-acrylamide as crosslinker and potassium persulfate as initiator. The influences of the amount of initiator and crosslinker, neutralization degree of acrylic acid(AA), ratio of starch to AA, microwave power level and irradiation time on the distilled water absorption amount of resin were investigated. The results indicated that it only needed 4min under the microwave level of 231W to obtain the resin with the maximum absorption amount of 1110g×g-1, under the conditions that 0.3wt% initiator, 0.02wt% crosslinker, 60% neutralization degree of acrylic acid, the ratio of starch to acrylic acid of 0.25. Under microwave irradiation, the synthesis and drying of super absorbent resin could be completed at one step without nitrogen. Compared to conventional heating method, the methods had the striking advantages of short reaction time, simple process and low cost.

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.

Meso-mechanics simulation analysis of microwave-assisted mineral liberation

2015 ◽  
Author(s):  
Qin Like ◽  
Dai Jun ◽  
Yuan Liqun
Keyword(s):  
Energy Consumption ◽  
Microwave Irradiation ◽  
Power Density ◽  
Microwave Power ◽  
Mineral Content ◽  
Crystal Size ◽  
Irradiation Time ◽  
Mineral Crystal ◽  
Microwave Assisted ◽  
Time And Energy

Microwave-assisted crushing and grinding can improve efficiency and reduce energy consumption. This paper takes rock grains with galena and calcite as the research object to establish a two-dimensional computational model through the finite difference software FLAC2D. It analyzes the process and law of mineral boundary failure under microwave irradiation, and assesses the effects of four factors, namely, microwave irradiation time, power density, mineral crystal size, and mineral content, on mineral boundary failure. Results indicate an optimal microwave irradiation period for the rapid failure of mineral boundary. Moreover, irradiation time and energy consumption can be reduced by increasing the microwave power density. However, irradiation time and energy consumption are basically unchanged when the microwave power density is above a certain threshold. Mineral content slightly affects the microwave irradiation time, whereas mineral crystal size significantly affects the microwave irradiation time. In addition, a larger-sized mineral crystal requires less irradiation time and energy consumption to reach the same failure rate. However, irradiation time and energy consumption slightly change when the crystal size is larger than a certain value.

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