Application Of Microwave Irradiation Research Articles

The Remediation of Petroleum Contaminated Soils Using Microwave Irradiation: A Laboratory Study

A laboratory study was conducted to remediate petroleum contaminated soils using microwave irradiation, and the traditional method of electric heating was also used for comparison purpose. The feasibility of the microwave irradiation method was evaluated in aspects of the reaction time, petroleum removal efficiency and energy consumption level. Meanwhile, the impacts of microwave irradiation mode and soil conditions on petroleum removal efficiency were also investigated, with a thermodynamic model of soils specifically developed. The results showed that microwave irradiation was better than the traditional heating method in remediating petroleum contaminated soils with less energy consumed. Also, microwave irradiation time, microwave power, soil moisture content and soil petroleum content had all imposed significant impacts on the remediation efficiency, and the results obtained from the model were basically consistent with the experiment results. Therefore, the findings from this study are of significance in real-world applications of microwave irradiation for the remediation of petroleum contaminated soils.

Graft Copolymerization of Chitosan with L-Lactide under Microwave Irradiation

Poly (L-lactide) was grafted onto chitosan by ring-opening copolymerization under microwave irradiation in the presence of tin octoate (Sn (Oct)2) as catalyst. The chemical structure and physical properties of the copolymers with different feeding ratios were discussed by FTIR, DTG and X-RD, taking pure chitosan as reference. The results showed that the application of microwave irradiation in the reaction could achieve the copolymer with high grafting percentage in a short time and low temperature. The thermal stability and crystallinity were decreased with the feeding ratio increasing, attributing to the increasing of grafting percentage.

Application of Microwave Irradiation and Heat to Improve Gliadin Detection and Ricin ELISA Throughput with Food Samples.

The utility of microwave irradiation to accelerate the onset of equilibrium and improve ELISA performance was examined using ELISAs for the detection of the plant toxin ricin and gliadin. The ricin ELISA normally requires several one hour incubations at 37 °C, a total assay time of approximately five hours, and employs a complex buffer containing PBS, Tween-20®, and non-fat milk. Different energy levels and pulse designs were compared to the use of abbreviated incubation times at 37 °C for the detection of ricin in food. The use of microwave irradiation had no significant advantage over the application of heat using an oven incubator and performed worse with some foods. In contrast, a gliadin ELISA that relied on 30 min incubation steps at room temperature and a salt-based buffer performed better upon irradiation but also displayed improvement upon incubating the microtiter plate at 37 °C. Whether microwave irradiation was advantageous compared to incubation in an oven was inconclusive. However, by abbreviating the incubation time of the ricin ELISA, it was possible to cut the assay time to less than 2 hours and still display LOD values < 10 ppb and recoveries of 78%–98%.

ChemInform Abstract: Microwave‐Assisted Synthesis of Five‐Membered O‐Heterocycles

AbstractReview: developments in the last 5—10 years; 80 refs.

ОСНОВНЫЕ НАПРАВЛЕНИЯ ИСПОЛЬЗОВАНИЯ МИКРОВОЛНОВОГО ИЗЛУЧЕНИЯ ПРИ ПЕРЕРАБОТКЕ РАСТИТЕЛЬНОГО СЫРЬЯ (ОБЗОР)

The use of microwave radiation in the chemistry of plant raw materials in the last decade attracted the attention of a growing number of scientists. The present review publications in this field in recent years, the number of which increases exponentially. The main field of application of microwave radiation in the chemistry and technology of vegetable raw materials: extraction of natural plant facilities for the low molecular weight compounds of different classes in the individual state and the form of compositions (eg, essential oils); selection of high structural biopolymers (cellulose, lignin, hemicellulose); The drying process plant facilities; pyrolysis of wood; hydrolysis of high-molecular components of plant raw materials; chemical modification of vegetable origin of biopolymers to obtain ethers and esters and other derivatives; chemical modification of plant raw materials without prior separation into individual components and some other processes. The efficiency of the microwave radiation in these processes. It is noted that the microwave radiation is generally conducted considerably faster process and significantly reduces energy costs. The examples of processes described in the industry. Processes and mechanisms that occur when exposed to microwave radiation plant material is currently not well understood and require further investigation.

Use of EMW Radiation in the Building Industry

This paper discusses theory and application of microwave radiation and experimental optimization of microwave radiation to eliminate moisture content in wood elements. Owing to its properties, microwave radiation has been used in the construction industryin modern times, in particular to dry wet masonry of buildings. Effects of electromagnetic radiation on building structures lead to relatively sharp decreases in moisture content from damp building structures or elements. The influence of electromagnetic radiation on building structures lead to oscillation of water molecules contained in the material, which cause a phase transformation of water into vapour. Consequently, the vapour evaporates from the moist material, thereby drying the element exposed to radiation.The article describes experiments carried out at the Faculty of Civil Engineering of the Faculty of Technology in Brno that demonstrate successful decrease of water content in building materials using microwave radiation. First, the understanding of microwave radiationwill be discussed.Following an analysis of research results an optimum intensity of microwave radiation sources as well as the necessary length of the irradiation of microwave radiation have been determined with respect to the particular type of building material and the success rate of elimination of moisture.

Influence of Microwave Synthesis Dissolution Technique on the Kinetics Properties of Polymer Dope Solution

The application of Microwave Irradiation has become a frequent heating source in organic and inorganic materials synthesis. Inspired by this vast achievement, the use of microwave irradiation is highly studied for polymer synthesis. The influence of modified microwave system on the solubility and kinetics properties of the polyethersulfone (PES) dope solution has been investigated. A modified microwave (MW) assisted closed heating system was applied to prepare the PES dope solution in single solvent; dimethylformamide (DMF) and mixture of two solvents DMF/acetone for membrane fabrication. Providentially, most of the synthetic polymeric membrane materials are polar and dipolar which is a very important factor in microwave processing. New MW systems have given incredible properties in terms of viscosity, shear stress, shear rate and yield stress of polymer dope solutions. The results revealed that MW assisted pure PES solution exhibits pseudoplastic and Newtonian behaviour respectively. However, PES solution containing the two solvent system exhibits dilatants behaviour, which obeys the power-law. The apparent viscosity of the PES dope solutions prepared using the DMF is lower as compared to those prepared using the DMF/acetone. Rheological properties measured include apparent viscosity at various shear rates. Subsequently the flow behaviour (n) and consistency index (k) is determined.

Application of microwave radiation in innovative process of neutralising asbestos-containing wastes

Presented are results of a research on a possibility to use innovative microwave heating for thermal neutralisation of asbestos-containing wastes. In comparison to traditional heating, the innovative process is characterised by up to a hundred times reduced energy consumption and two hundred times shorter processing time. Parameters of effective disposal, i.e. microwave radiation power and heating time, as well as kind and quantity of the wetting agent necessary in the microwave heating process that intensifies the process and ensures uniform heat distribution in the heated charges, were determined for five most commonly used products containing various fractions of asbestos fibres. It was demonstrated that the presented innovative and eco-minded technology of disposing asbestos-containing materials is a quick, cheap, economical and effective solution guaranteeing complete degradation of the hazardous fibres.

Microwave-promoted synthesis of bicyclic azocine-β-lactams from bis(allenes).

A metal-free preparation of structurally novel bicyclic azocine-β-lactams has been developed. The first examples accounting for the preparation of eight-membered rings from bis(allenes) in the absence of metals have been achieved by the thermolysis of nonconjugated 2-azetidinone-tethered bis(allenes) on application of microwave irradiation. This selective carbocyclization reaction has been studied experimentally, and additionally, its mechanism has been investigated by a DFT study.

The Effect of Solvent, Hydrogen Peroxide and Dioxide Titanium on Degradation of PCBs, Using Microwave Radiation in Order to Reduce Occupational Exposure

Abstract Polychlorinated biphenyls (PCBs) are one group of persistent organic pollutants (POPs) that are of international concern because of global distribution, persistence, and toxicity. Removal of these compounds from the environment remains a very difficult challenge because the compounds are highly hydrophobic and have very low solubility in water. A 900 W domestic microwave oven, pyrex vessel reactor, pyrex tube connector and condensing system were used in this experiment. Radiation was discontinuous and ray powers were 540, 720 and 900 W. The PCBS were analyzed by GC-ECD. The application of microwave radiation and H2O2/TiO2 agents for the degradation of polychlorinated biphenyl contaminated oil was explored in this study. PCB – contaminated oil was treated in a pyrex reactor by microwave irradiation at 2450 MHz with the addition of H2O2/TiO2. A novel grain TiO2 (GT01) was used. The determination of PCB residues in oil by gas chromatography (GC) revealed that rates of PCB decomposition were highly dependent on microwave power, exposure time, ratio to solvent with transformer oil in 3:1, the optimal amount of GT01 (0.2 g) and 0.116 mol of H2O2 were used in the study. It was suggested that microwave irradiation with the assistance of H2O2/TiO2 might be a potential technology for the degradation of PCB – contaminated oil. The experiments show that MW irradiation, H2O2 oxidant and TiO2 catalyst lead to a degradation efficiency of PCBs only in the presence of ethanol. The results showed that the addition of ethanol significantly enhanced degradation efficiency of PCBs.

Development of an innovative microwave assisted food freezing process

In this study, a novel experimental setup was developed and an innovative process was implemented aiming at the application of microwave radiation during freezing of a food matrix. The results acquired from the present study are considered as remarkable and promising. The developed freezing process was applied on pork tenderloin samples. The application of microwaves during cooling the samples caused oscillated decrease of temperature and had a significant impact on the crystallization process as the degree of supercooling was decreased circa 92% under the tested conditions. The meat microstructure evaluation showed a 62% decrease in the average ice crystal size when samples were frozen under a microwave field as compared to the conventional freezing process. These results indicate that the application of microwave radiation during freezing may reduce the damage of the meat tissue and in turn to retain better texture in the frozen meat. The reduction of freeze damage exerted to any tissue undergoing freezing remains a challenge. The mechanical and biochemical stress caused by the ice crystals to the cellular membranes results in irreversible tissue damage. The application of electric and/or magnetic disturbances has been identified as a possible means to reduce the size of ice crystals during freezing of biological tissues. In the present study microwaves were applied during freezing of pork meat. Our results indicate that the size of the formed ice crystals was significantly reduced during microwave assisted freezing leading to a lower damage on the microstructure of meat. This paper describes an innovative and novel freezing process that could be used in order for higher quality frozen products to be produced. • Freezing of pork meat under microwave irradiation has been investigated. • The size of ice crystals was reduced by 62% between control and the higher tested microwave power level. • Significant impact on the crystallization process was observed during the microwave assisted freezing of pork meat.

Regioselective Piperidine-Catalyzed Tandem Imination–Isocyanate Annulation to Fused Tricyclic Triazines

A novel tandem imination-isocyanate-mediated annulation was explored. Ionic liquid-immobilized 2-aminobenzimidazoles react sequentially with aldehydes and isocyanates to give highly functionalized benzimidazole-embedded triazines. The second-stage transformation revealed that the formation of triazinone functionality is entirely regioselective to allow rapid assembly of biologically interesting tricyclic skeletons. In conjunction with the application of microwave irradiation and IL support, this method provides an efficient route to access substituted benzoimidazotriazines.

Microwave drying of a low-rank sub-bituminous coal

The moisture contents of coals are often too high and need to be reduced before further processing. In this study, the application of microwave radiation as an alternative energy source for the drying of a sub-bituminous coal was investigated. Firstly, the permittivities of the coal were evaluated as a function of temperature and frequency. Secondly, the drying kinetics were studied in a 2.45GHz microwave system and the effects of incident microwave power, sample mass and initial moisture contents were determined. The results demonstrated that microwave drying had several advantages over conventional drying such as increased drying rates and lower final moisture contents. In some tests, magnetite was added as a susceptor to increase the drying rates. Thirdly, the drying data were fitted to ten exponential decay models, and although reasonable agreement was observed with all the models, the best fit was obtained with the Midilli–Kucuk model. Finally, the effective diffusion coefficients of moisture and also the activation energy of the diffusion process were estimated and used to further elucidate the mechanism of microwave drying.

Inclusion of fenofibrate in a series of mesoporous silicas using microwave irradiation

A selection of porous silicas were combined with a model drug using a recently developed, controlled microwave heating process to determine if the application of microwave irradiation could enhance subsequent drug release. Five mesoporous silica types were investigated (core shell, core shell rehydrox, SBA-15, silica gel, SYLOID®) and, for comparison, one non-porous silica (stober). These were formulated using a tailored microwave heating method at drug/excipient ratios of 1:1, 1:3 and 1:5. In addition, all experiments were performed both in the presence and absence of water, used as a fluidising media to aid interaction between drug and support, and compared with results obtained using more traditional heating methods. All formulations were then characterised using differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transformation infrared spectroscopy (FT-IR). Pharmaceutical performance was investigated using in vitro drug release studies. A significant enhancement in the release profile of fenofibrate was observed for formulations prepared using microwave heating in the absence of water for five of the six silica based formulations. Of all the formulations analysed, the greatest extent of drug release within the experimental 30min was the 1:5 core shell rehydrox achieving a total of 86.6±2.8%. The non-porous (stober) particles did not exhibit an increased release of the drug under any experimental conditions studied. This anomaly is thought to be a result of the comparatively small surface area of the silica particles, thus preventing the adsorption of drug molecules.

Hyperbranched polyurethane/Fe3O4 nanoparticles decorated multiwalled carbon nanotube thermosetting nanocomposites as microwave actuated shape memory materials

Abstract

Sterilization of Biotic Pests by Microwave Radiation

Some of the issues connected to timber structures are caused by wood-destroying insects. The sterilization of timber elements affected by wood-destroying insects with the help of microwaves removes the deficiencies of other available methodologies. Hence the given paper deals with the experimental sterilization of wood-destroying insect by the application of microwave radiation. It explains the principles behind heating with microwaves and also describes the biological effects of microwave radiation in a simplified manner. The following chapter introduces the equipment required for microwave sterilization to take place and the actual experimental sterilization process. In the final part of the paper are the results of the experimental activity. Throughout the experiments it was found out that microwave radiation seems to be an effective methodology to sterilize wood-destroying beetles. Within the conclusion the intensity of microwave radiation needed for a successful and effective sterilization process is recommended together with the time along which the timber element must have a constant temperature achieved by heating in the primary phase.

Microwave-Assisted Synthesis of 2-(2-Nitroethenly)thiophene from 2-Thiophenecarboxaldehyde and Nitromethane

2-(2-Nitroethenly)thiophene can be obtained from 2-thiophenecarboxaldehyde and nitromethane under Knoevenagel condensation conditions. We used beta-alanine as a catalyst and microwave irradiation as the energy source. Different reaction condition, such as beta-alanine consumption and reaction time were studied. The results indicate that the application of microwave irradiation increases the yield of desired compound. beta-Alanine-catalyzed activation of 2-thiophenecarboxaldehyde provides an efficient access to 2-(2-nitroethenly)thiophene with reusability of the catalyst.

ChemInform Abstract: Microwave‐Assisted Synthesis of Medium‐Sized Heterocycles

AbstractReview: 94 refs.

Review of the application of ionic liquids as solvents for chitin

Abstract Chitin is one of the most abundant biopolymers, but due to its high crystallinity, it is completely insoluble in most organic and inorganic solvents. Chitin is soluble only in solvents that can destroy intersheet and intrasheet H-bonds, and many of these solvents are toxic, corrosive, nondegradable, or mutagenic. Because of these drawbacks, there is a search for more environmentally friendly solvents for chitin. It has been shown that ionic liquids (ILs) can dissolve chitin at elevated temperatures (80°–110°C) or with application of microwave irradiation. The highest solubility of chitin in an IL was about 20% (1-ethyl-3-methylimidazolium acetate), whereas chitin was shown to be insoluble in 1-allyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium formate. Dissolved chitin can be regenerated by mixing with water or methanol, where the polymer precipitates from the solution. X-ray diffraction patterns of native polymer and precipitates have been compared and only small changes in crystallinity have been observed. In addition, Fourier transform infrared spectra remained similar for both forms of chitin, native and regenerated. Presented data hold great promise for the improvement of the chemistry of chitin and open new routes for chemical and enzymatic modifications of this polymer.

Microwave high performance liquid chromatography with UV-visible detection. Application to vitamins determination

The present work describes the first attempt to use microwave reversed phase high performance liquid chromatography (MW-HPLC) to carry out the separation of organic compounds. Biotin and riboflavin were selected for the characterization of the new separation technique. Additional vitamins (nicotinamide, pyridoxine and thiamine) were used as reference compounds. In order to perform the separation, a chromatographic column was placed inside a domestic microwave oven in a hanging position. The column particular location was an extremely critical point, since it precluded the actual power absorbed by the sample. In order to avoid magnetron damage, a heat well (i.e., water vessels) was used. Vitamins were detected using a UV-VIS detector. Results obtained showed that the application of microwave radiation, even at low power levels, gave rise to a significant modification in the characteristics of the chromatograms. It was found that retention times for biotin and riboflavin shortened as the power increased. Furthermore, the peak shape also changed, with the modification being more significant for the former vitamin than for the latter one. Furthermore, sensitivity also increased as the column was exposed to the action of microwave. Comparatively speaking, MW-HPLC was more efficient in terms of compound separation than when performed at room temperature or thermostatted at 45 °C HPLC. This was likely due to the combined action of a moderate and quick heating of the mobile phase with an increase in the analytes diffusivity caused by the radiation.