Sol-Gel Derived Binder for Inorganic Composites

A new low cost inorganic binder system for large volume products like fiber insulation, building materials, etc. has been developed based on sol-gel technology. The precursor for the binder system is an amorphous mineral raw material containing silica as the major component. The sol was prepared by dissolving the amorphous mineral material in formic acid and the mineral was dissolved in a few hours dependent on the molarity of the formic acid. The sol stability was dependent on the solids content and the pH. The gel formation was studied using light scattering and NMR. The results show a growing particle size of particles mainly consisting of silica while the other cations were dissolved in the pore liquid. During the drying of the wet gels, salts of these cations were crystallized in the pores and further decomposed during heating. The derived binder shows good wetting properties to mineral fiber surfaces and a good strength of paper-binder composites. The new binder system applicable to approximately 800°C has a great potential as a substitute for some traditional organic systems.     

Quantification of amorphous content in mixed systems: amorphous trehalose with lactose

There has been a lot of interest in quantification of the amorphous content of materials, especially when the amorphous content is a small percentage of the total mass. Whilst there has been success in studies on single materials, there has been little work showing how quantification of the amorphous content of one material can be undertaken in the presence of another. In this work isothermal microcalorimetry was used to measure the content of amorphous trehalose following mixing with crystalline lactose. Gravimetric water sorption studies revealed that trehalose did not form a complete dihydrate when exposed to 75% RH, presumably due to the rapid crystallisation of the outer regions of the particles. At 53% RH, the gravimetric studies showed dihydrate formation. The calorimetry data revealed that the crystallisation response was directly related to the mass of amorphous material in the mixture and was not affected by the mass of non-crystallising sample. It was shown that as long as there was a minimum mass of amorphous material (in this case 4 mg), it was possible to measure a crystallisation response with sufficient accuracy to allow quantification. Lower masses of amorphous content allowed detection, but less accurate quantification, as the response was superimposed on the initial calorimetric heat flow response. It was also found that the response at 53% RH in the TAM was less accurate due to the low peak height and long duration (compared to that seen at 75% RH). It can be concluded that the TAM method is well suited to both detection and quantification of amorphous content when there is one amorphous sample mixed with another (and thus presumably more than one) non-crystallising material.     

Application of FT-Raman spectroscopy to quality control in brick clays firing process

This paper reports the study of the mineralogical evolution during the firing process (800-1150 degrees C) of the main types of raw materials used for the brick industry in Santa Cruz de Mudela (Ciudad Real, Spain). The mineralogical diversity observed in these materials leads to different behaviour during the shaping, drying and firing stages. Traditional use of similar working conditions in local industries, despite the mineralogical differences in the starting material, promotes the presence of defects in the drying and/or firing stages. This study attempt to implement some analytical guideline for the raw materials in order to improve the final product. Three types of raw materials obtained in different quarries have been characterised by means of chemical analysis with electron microprobe, powder X-ray diffraction and FT-Raman spectroscopy. The main difference between the clays studied is the carbonate content: one of the analysed samples is deficient in this component, while it is present as calcite (8%) or as calcite (14%) plus dolomite (10%) in the rest. The observed compositional differences seem to be relevant in the firing process. FT-Raman spectra reveal the onset of early vitrification (at about 900 degrees C) in the sample without carbonate. The importance of calcium and magnesium oxides, obtained from the corresponding carbonates, for the synthesis of new mineral phases that could slow down the vitrification process is discussed.     

Improved electrode fabrication method to enhance performance and stability of MoS2-based lithium-ion battery anode

Choice of binder and the electrode-making process play a pivotal role in the electrochemical performance of MoS₂, when used as lithium-ion battery anode. In this work, MoS₂ nanorods are prepared by gas phase synthesis method using molybdenum trioxide (MoO₃) nanobelts and sulfur as starting materials. It has been observed that by tuning the reaction conditions, morphology and yield of the final product can be controlled. Carboxymethyl cellulose (CMC) is used as binder to fabricate the MoS₂ electrode, and its electrochemical performance is tested against Li/Li⁺. The performance of electrode can be further improved by incorporating heat treatment to the active material and conductive carbon mixture prior to electrode fabrication. The electrochemical data shows that the optimum temperature for heat treatment is 700 °C. In the current report, we would like to elucidate a detailed study based on electrode fabrication process and their impact on the electrochemical performance.     

Thermal degradation of rice husks on a pilot plant

This study is an attempt to establish the possibilities to obtain black rice husk ash (BRHA) and white rice husk ash (WRHA) via pyrolysis of wasted raw rice husks in a pilot plant fluidized-bed reactor at different conditions. The process course auto thermally, without outer fuel. The released heat may be used for steam obtaining or drying. The solid products obtained (BRHA or WRHA) are characterized using X-ray diffraction patterns, thermal analysis, and low temperature nitrogen adsorption. Using batch adsorption technique, the kinetics was studied and the adsorption capacities of crude oil and diesel fuel at different temperatures as well as some hydrocarbons at 298?K onto BRHA and WRHA are determined. It was established that BRHA have been higher adsorption capacity than WRHA. At a given temperature, BRHA sorbed more crude oil than diesel fuel. The results obtained showed that the material studied has high adsorption capacity and low cost and may successfully be used as an effective adsorbent to cleanup of bilge water and spills of oil and oil products in water basins. Because the saturated BRHA with crude oil, diesel fuel or different hydrocarbons are characterized with high calorific, they can be burnt in incinerators, industrial ovens or steam generators. By this way, we attain not only ecological but also economical effect.     

Recycling of polymeric composites

For material recycling, composites have to be separated into their components, as only non-mixed raw materials can grant high quality standards. A combined mechanical and subsequent electrostatic separation can be classified as highly economic because it is a dry treatment. This is demonstrated on wire scrap. The separated copper and synthetic materials are obtained in a high degree of purity. Chemical disaggregation of composites has been worked out with medicinal blister packs and beverage packs. Two methods of separation were used: separating the plastic-aluminium composite by dissolving the plastic material or dissolving the adhesive that bonds together the plastic and aluminium. To demonstrate the technical feasibility of the processes, a pilot plant with a capacity of up to 25 tons of blister pack material per year was built. Chemical separation with non-problematic aqueous media was demonstrated with flocked plastics. When integrating composites into chemical processes, questions concerning material specification as well as preparation and chemical utilization must be answered. Mechanical preparation of appropriate raw materials has been exemplified by mixed packing waste, carpet-floor waste, and synthetic material from electrical waste. After the raw materials were analyzed and studies of their quantity and compositions were made, their possible re-use as raw material within a chemical process has been elaborated.     

Coupling sol-gel synthesis and microwave-assisted techniques: a new route from amorphous to crystalline high-surface-area aluminium fluoride

A non-aqueous sol-gel Al-based fluoride has been subjected to the microwave solvothermal process. The final material depends on the temperature heat treatment used. Three types of material have been prepared: 1) for low temperature heat treatment (90 degrees C) X-ray amorphous alkoxy fluoride was obtained; 2) for the highest temperature used (200 degrees C) the metastable form beta-AlF3 was obtained with a very large surface area of 125 m2 g(-1). The mechanism of the amorphous=crystalline transformation has been rationalised by the occurrence of a decomposition reaction of the gel fluoride induced by the microwave irradiation. 3) Finally, at intermediate temperature (180 degrees C) a multi-component material mixture exhibiting a huge surface area of 525 m2 g(-1) has been obtained and further investigated after mild post-treatment fluorination using F2 gas. The resulting aluminium-based fluoride still possesses a high-surface-area of 330 m2 g(-1). HRTEM revealed that the solid is built from large particles (50 nm) identified as alpha-AlF3, and small ones (10 nm), relative to an unidentified phase. This new high-surface-area material exhibits strong Lewis acidity as revealed by pyridine adsorption and catalytic tests. By comparison with other materials, it has been shown that whatever the composition/structure of the Al-based fluoride materials, the number of strong Lewis acid sites is related to the surface area, highlighting the role of surface reconstruction occurring on a nanoscopic scale on the formation of the strongest Lewis acid sites.     

The micro-distribution of carbonaceous matter in the Murchison meteorite as investigated by Raman imaging

The carbonaceous Murchison chondrite is one of the most studied meteorites. It is considered to be an astrobiology standard for detection of extraterrestrial organic matter. Considerable work has been done to resolve the elemental composition of this meteorite. Raman spectroscopy is a very suitable technique for non-destructive rapid in situ analyses to establish the spatial distribution of carbonaceous matter. This report demonstrates that Raman cartography at a resolution of 1 microm2 can be performed. Two-dimensional distribution of graphitised carbon, amorphous carbonaceous matter and minerals were obtained on 100 microm2 maps. Maps of the surface of native stones and of a powdered sample are compared. Graphitic and amorphous carbonaceous domains are found to be highly overlapping in all tested areas at the surface of the meteorite and in its interior as well. Pyroxene, olivine and iron oxide grains are embedded into this mixed carbonaceous material. The results show that every mineral grain with a size of less than a few microm2 is encased in a thin carbonaceous matrix, which accounts for only 2.5 wt.%. This interstitial matter sticks together isolated mineral crystallites or concretions, including only very few individualized graphitised grains. Grinding separates the mineral particles but most of them retain their carbonaceous coating. This Raman study complements recent findings deduced from other spatial analyses performed by microprobe laser-desorption laser-ionisation mass spectrometry (microL2MS), transmission electron microscopy (TEM) and scanning transmission X-ray microscopy (STXM).     

Impurity paramagnetic Fe(III) and Mn(II) centers in samples of amorphous silica of different origin

Some important magnetic and local structural properties of amorphous silica separated from biogenic (fruit shell of rice and oats, larch and Korean spruce needles, horsetail pedicels, and diatomic algae) and mineral raw were determined by the method of electron paramagnetic resonance. The data obtained can be useful when selecting raw materials and for development of processing scheme of its treatment to separate silicon(IV) oxide with required characteristics.     

Effects of different carriers on the production of isoflavone powder from soybean cake

The objectives of this study were to use soybean cake as the raw material for the production of isoflavone powder and compare the effects of different carriers as well as drying methods on the powder quality. Results showed that with spray drying, a level of 40% maltodextrin as carrier produced the highest yield (mass) of isoflavone powder, followed by 10% gelatin and 1% sodium alginate. However, a reversed trend was observed for the isoflavone content. With 1% sodium alginate, freeze drying generated the greatest yield of isoflavone powder, followed by vacuum drying and spray drying. The isoflavone content also exhibited the same tendency. With poly-gamma-glutamic acid (gamma-PGA) as carrier, all six levels studied (0.57, 0.28, 0.14, 0.028, 0.014 and 0.003%) were capable of forming powder containing high amounts of total isoflavone, which was comparable to that using 1% sodium alginate by freeze drying. Both high- and low-molecular-weight gamma-PGA showed similar effects in terms of powder yield and isoflavone content.     

Pathogenic Mineralization on Human Heart Valves. III. Electron Microscopy

Pathogenic mineral formations on human cardiac valves have been studied by electron microscopy, as well as high-resolution scanning and transmission microscopies. These are bacteriomorphic mineral formations, as indicated by the globular form of the mineral component represented by the carbonate-containing hydroxyl apatite, by aggregation of the component in colonies, and by the bacterial proper and bacterial glycocalix residues recorded in the samples. The composition and internal structure of the mineral component, as well as the nanosize of the apatite crystals, correlate with the presence of the amorphous and crystalline phases, whose ratio changes from sample to sample and is comparable with the Ca/P atomic ratio.     

Raman characterization of orientation in poly(lactic acid) films

Poly(lactic acid) is a new biopolymer material which is marketed by Cargill Dow Polymers under the tradename Nature Works*. One major application for this material is biaxially oriented films for food packaging because it possesses excellent barrier for flavor constituents, deadfold and heat sealability. Shrinkage must be minimized when the film is heat sealed for these applications and, therefore, characterization of the orientation of the amorphous phase of PLA films is necessary. Raman spectroscopy methodology has been developed to quantify orientation in PLA films. Bands were assigned to crystalline and amorphous phases of PLA such that orientation in both phases could be monitored. Raman depolarization ratios were used to characterize uniaxial systems but were insufficient for most biaxial draws. A new phenomenon for oriented films involving Raman band shifts was observed in these systems, and was shown to be capable of determining orientation, even for symmetrical biaxially drawn films. The origin of these shifts, as well as their use for the quantification of orientation will be discussed. Further, since the line widths of the bands could be used to quantify crystallinity, both crystallinity and orientation could be determined with one measurement.     

Change in the mineral composition of phytates

The mineral composition of phytin has been studied as a function of the variety of the source of raw material and the possibility of its change during the process of isolation.All-Union Scientific-Research Chemical and Technological Institute of the Medicinal Industry, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 695–698, September–October, 1991.     

Ignition and combustion characteristics of compound of magnesium and boron

Compound of magnesium and boron (MB) is promising to be the ideal substitute of amorphous boron which is usually used as the raw material of boron-based fuel-rich propellants. In this study, the physical characteristics of MB and amorphous boron were studied by the scanning electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy. The thermal reaction characteristics and the ignition and combustion characteristics were investigated through TG/DSC experiments and laser ignition experiments. The experimental results show that the MB particle is much more regular than amorphous boron, which favors for the preparation of boron-based fuel-rich propellants. Magnesium exists in the form of elementary substance, and boron oxide is produced during the preparation of MB which results in the longer ignition delay time of MB. The content of magnesium and the pressure have effects on the MB combustion performance. Although the combustion of magnesium can provide much heat for the combustion of boron, MB with moderate content of magnesium shows the best combustion performance. On the contrast, the ignition delay time of MB is independent on the content of magnesium and the pressure.     

Investigation of the pyrolysis behaviour of brown algae before and after pre-treatment using PY-GC/MS and TGA

The pyrolysis behaviour of a number of brown macroalgae (seaweeds) collected in the UK such as Laminaria hyperborea and Fucus vesticulosus, are compared with the tropical algae Macrocystis pyrifera. Macroalgae contain a significant amount of alkali earth metals, halogens and a range of trace heavy metals. Pre-treatment of the algae has been performed to remove mineral matter in both water and weak acid. The pyrolysis behaviour of the residues has been investigated and the effect of processing on ash content and mineral composition has been determined. The pyrolysis behaviour of the raw samples and the residues from processing has been studied using thermal gravimetric analysis (TGA) and pyrolysis-GC/MS (Py-GC/MS). Total mineral matter has been determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) before and after pre-treatment. The Py-GC/MS pyrograms at 500 °C indicate the presence of a range of ketones, pentosans, nitrogen containing compounds and phenols. The residues from pre-treatment have different pyrolysis behaviours, particularly after acid treatment. The pre-treatment schemes investigated can remove a significant proportion of the mineral matter and halogens although they also selectively extract polymeric material. The residues have lower ash content and lower nitrogen content. Results for pre-treatment in water are consistent with the removal of mannitol, while results for pre-treatment in acid are consistent with the removal of fucoidan, mannitol and the partial removal of laminarin. Py-GC/MS of the residue from pre-treatment in acid produces a similar pyrogram to alginic acid in which furfural is a dominant product. There appears to be potential for the production of fuels and chemicals from brown algae by pyrolysis although the reduction of mineral matter and halogens by pre-treatment is advantageous.     

Change in the mineral composition of phytates

The mineral composition of phytin has been studied as a function of the variety of the source of raw material and the possibility of its change during the process of isolation. All-Union Scientific-Research Chemical and Technological Institute of the Medicinal Industry, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 695–698, September–October, 1991.     

Tracking soil transport to sugarcane industry using neutron activation analysis

Soil as mineral impurity in sugarcane loads impacts the Brazilian sugar-ethanol industry with rising production and maintenance costs as well as decreased productivity. The mechanical harvesting of sugarcane was conceived as a technology with potential to increase the raw material quality thereby has been gradually replacing manual harvesting throughout the country. Instrumental neutron activation analysis was applied for determination of soil tracers in order to compare the performance of both harvesting systems in terms of mineral impurities. There were no significant differences in the amount of soil transported to sugarcane industry despite the technological progress aggregated to mechanical harvesting. However, for both harvesting systems there were significant differences on the amount of such mineral impurity between clay and sandy soils.     

The effect of magnetic field on conductive films

Conductive paints consisting of nickel powder (conductive material), solvent, and binder polymer were treated in a magnetic field. The efficiency of magnetic treatments on conductivity of coating films was evaluated. The effect of the following factors on conductivity of composite films by magnetic treatment was studied: metal powder concentration, magnetic flow density, time difference between film preparation and magnetic treatment, drying time of paint films, and effect of distance between terminals. Results showed that the volume resistivity of paint films treated magnetically was lower than that for untreated films at each nickel content. Magnetic treatment provided high conductivity even at low magnetic flow density, and conductivity increased with magnetic flow density.     

Isothermal and solution calorimetry to assess the effect of superplasticizers and mineral admixtures on cement hydration

The heat of hydration evolution of eight paste mixtures of various water to binder ratio and containing various pozzolanic (silica fume, fly ash) and latent hydraulic (granulated blast furnace slag) admixtures have been studied by means of isothermal calorimetry during the first 7 days of the hydration process and by means of solution calorimetry for up to 120 days. The results of early heat of hydration values obtained by both methods are comparable in case of the samples without mineral admixtures; the values obtained for samples containing fly ash and granulated blast furnace slag differ though. The results from isothermal calorimetry show an acceleration of the hydration process by the presence of the fine particles of silica fume and retarding action of other mineral admixtures and superplasticizer. The influence of the presence of mineral admixtures on higher heat development (expressed as joules per gram of cement in mixture) becomes apparent after 20 h in case of fly ash without superplasticizer and after 48 h for sample containing fly ash and superplasticizer. In case of samples containing slag and superplasticizer the delay observed was 40 h. The results obtained by solution calorimetry provide a good complement to the ones of isothermal calorimetry, as the solution calorimetry enables to study the contribution of the mineral admixtures to the hydration heat development at later ages of the hydration process, which is otherwise hard to obtain by different methods.     

Novel binding material for supercapacitor electrodes

Environmentally friendly water-based composite material has been investigated as a novel binder for manufacturing supercapacitor electrodes. The performance of these electrodes and those with the conventional polyvinylidene fluoride (PVDF) binder were studied. Results obtained from cyclic voltammetry, electrochemical impedance spectrometry, and charge/discharge measurements showed that the electrodes with the new binder performed significantly better than the electrodes with the conventional PVDF binder; the specific capacitance increased by 51 % in an aqueous electrolyte while in an organic electrolyte, it increased by 15 %. This increase in capacitance was attributed to the electrophilic and hydrophilic nature of the new binding composite. The main reason for the improvement in capacitance was ascribed to reduction of equivalent series resistance (ESR). The presence of highly amorphous polyvinylpyrrolidone (PVP), a polymeric component of the new composite binder, was responsible for the reduction in ESR.