The ore was crushed to particle size of −212 µm. Con- ventional leaching experiments were carried out in glass vessels which were put in a temperature-controlled water bath. Stirring was carried out using an overhead mecha- nized stirrer and a glass impeller. 250 ml of the leaching solution was heated to the desired temperature and then 1.0 g of cassiterite ore was added. Periodic sampling of 5 ml of liquor was drawn for chemical analysis using ICP- OES (Inductively Coupled Plasma—Optical Emission Spectrometer).
Porous silicon samples, composed of PS layer with the same total surface areas of 0.95 cm 2 and silicon substrate, were fabricated by electrochemical anodization of silicon wafers in a solution of 1:1 (v/v) EtOH(99.5%)/HF(40%) . The electrochemical process was performed in a Teflon cell using two-electrode configuration with a Pt gauze as the cathode and silicon substrate as the anode, under the illuminating of 150 W high pressure mercury lamp and at a constant current density of 30 mA cm -2 for 30 min. After fabrication, the fresh porous silicon (f-PS) were rinsed with ethanol and acetone and then stored in ethanol to prevent oxidization.
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Electrochemical stability of Cu, Ni, Co, Pt, Ir metals sheet and their respective composite electrodes in potassium hydroxide (KOH) solution has been studied using cyclic voltammetry technique. The stability of those electrodes was quantified using Atomic Absorption Spectroscopy (AAS). The metal sheet electrodes were homely prepared in square cut of 1 cm by length and wide respectively. The powder composite electrodes were prepared by mixing together 95:5 (w/w) of the respective metals powder with polyvinyl chloride (PVC) using mechanical alloying technique. The result of the study showed that all metals sheet and their composite electrode except Cu were stable in a KOH solution. To study their stability further, those electrodes was then used in the electrooxidation process of ethanol in KOH solution, and their stability were quantitatively determined based on the analysis of the electrolysis solution using AAS. Base on the current density produced during the electrooxidation process, composite electrode was found to be more sensitive compared to metal sheet electrode.
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Methodology: We included 90 patients divided into 2 groups: group A (4% KOH), Includes 46 patients and group B (1% clotrimazole), and includes forty four patients. Skin scraping test was done for all patients. KOH was applied once daily, while clotrimazole solution twice daily for 2 or 4 weeks according to the response.
First, the iron electrodes were put in concentrated nitric acid for 1 min, then twice rinsed with distilled water to clean any surface pollutant. An electrochemical cell containing three iron electrodes (two cathodes and one anode) was immersed in potassium hydroxide solution. The different amounts of pulse currents were exerted into this cell to oxidize iron anode into iron oxide nanoparticles for 24 h. The prepared particles were then collected by a paper filter and dried at 400º C for 2 h. The effects of different parameters, such as reaction temperature, pulse current, pulse frequency, potassium hydroxide concentration and type and concentration of different additives, were optimized by the "one at a time” method to obtain uniform nanorods.
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gravity. While the carbondioxide gas flows upward. These two phases come in contact inspite of bubble caps, holes and valves that fill the area of the plates. Carbondioxide gas moves to the higher plate through these devices. While the potassium hydroxide solution move to the lower plate through a downcomer. Therefore a phase change occurs and mass transfer takes place by absorption of carbondioxide in to potassium hydroxide solution.The fluid is gathered to the base of the section while the gas is gathered to the top.
Environmental concerns due to fossil fuels combustion have led to extensive research on renewable energy sources including geothermal, solar, wind, and biomass. Biodiesel, derived from plant oils and animal fats is an attractive alternative fuel to fossil-based diesel as it is biodegradable, non-toxic, renewable, and has a low emission profile. It consists of a mixture of mono-alkyl esters of long-chain fatty acids chemically produced by transesterification of triglycerides (TG) or esterification of free fatty acids (FFA). A catalyst is generally required to speed up the reaction and improve yield[1, 2]. Industrial production of biodiesel faces major challenges including limited supply of raw material due to the utilization of high quality refined vegetable oils and, the cost of feedstock, which accounts for 60-80% of total production cost . At present, biodiesel is not economically competitive with petroleum based-fuels. In order to overcome some of these issues, use of inexpensive raw materials such as waste frying oils, non-edible oils, and animal fats have attracted attention of biodiesel producers[4, 5]. However, one main obstacle is that these low quality feedstock contain significant amounts of FFAwhich react with a base to produce soap and water hindering product separation during alkaline transesterification[5-7]. The problem of soap formation can be avoided by using acid-catalyzed transesterification but the slow reaction rate makes it a less attractive option .A method that has received more attention due to its moderate operating conditions, higher reaction rates and relative flexibility is the two- step estrification-transesterification process.In the esterificationstep fatty acids are converted to alkyl esters reducing FFA content to an acceptable level for the subsequent transeterification step, thus improving overall product yield. In the present study, different steps used in two-stage process are analyzed for their contributions to achieve improvedconversion efficiency at lower cost. In-situ water generation from different chemical reactions is considered with the objective of minimizing its detrimental effects. For the tranesterification step, a combination of potassium hydroxide and potassium carbonate is investigatedwith the objective to maintain good catalyst activity while avoiding detrimental effects of residual water in the reaction mixture.
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The reaction of 2-hydroxy 1-naphthaldehyde and chloroacetone in acetone gave 2- acetylnaphtho [2,1-b] furan. The compounds 1a-e was obtained by reaction of 2-acetylnaphtho [2, 1-b] furan with substituted aromatic aldehyde and aqueous solution of potassium hydroxide in ethanol and well characterized using its spectral and analytical data. The reaction of 1a-e with thiourea and conc. HCl in ethanol gaves 2a-e and characterized by using its Spectral and analytical data. Further the reaction of 2a-e with mono chloro acetic acid in presence of anhydrous sodium acetate glacial acetic acid and few drop of acetic anhydride gave titled compound 3a-e. It is characterized using spectral and analytical data and elemental analysis. Microbial screening of compounds showed good to moderate activity against the organism tested.
Abstract—The bamboo industry in Japan is declined, and disordered bamboo forests are increasing. Although maintenance of bamboo forest is needed, a large amount of bamboo wastes after logging is generated and left untreated. Therefore, new utilization of bamboo wastes after logging are desired. In this research, we aimed to develop a new recycling technology for bamboo using potassium hydroxide. By pyrolyzing bamboo using potassium hydroxide under an inert atmosphere, thermal decomposition of organic contents and alkali fusion of silica component inside the bamboo were carried out simultaneously to recover combustible gas, charcoal and silica component. The thermal decomposition behavior of bamboo, the properties of the obtained charcoal and extraction of silica in the presence of potassium hydroxide were investigated, and the optimum condition of bamboo recycling treatment was examined. As a result, it was found that when 1 g of bamboo was pyrolyzed at higher than 500 °C with 3 g of KOH, the almost silica was extracted, a large amount of fuel gas generated, and a carbonized material with specific surface area of about 1000 m 2 /g was obtained.
The cement is used widely all over the world because of its easily availability, binding properties & Strength. The production of cement is increased many times because of its popularity increased day by day.According to a recent survey the production of cement is estimated to be more than 2.8 billion tonnes and also estimated that the production of cement uses approximate 94.76 ×10 6 Joules The production of one ton of cement releases one ton of carbon di oxide gas in the atmosphere. As we all know carbon di oxide is responsible for green house gases which increases the warming. The carbon di oxide contributes about 65% to the green house effect. Therefore to reduce the negative effects of cement industry, new alternatives or supplementary are used.Geoploylmer is one such innovation.Geopolymer is a new technology in the history of concrete technology. It is also known as green concrete as it does not affect the environment. Geopolymer concrete can be prepared by use of waste materials like flyash, GGBS with the addition of chemicals such as sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium silicate or potassium silicate. The name Geopolymer was given By Dr. Prof. J. Davidovits in 1978 and he studied the polymerization process results in a chemical reaction under alkaline condition on Si-Al minerals which results in a 3D polymeric  Chain.The ring structure of this chain consist of Si-O-Al-O bond.the curing of mixture of geopolymer concrete can be done at ambient temperature or by heat curing .In this paper flyash is
In the recent years, there has been an increased interest in the physico-chemical properties of aqueous solution in polymer media 1-3 . In the recent years, it has been found that, the acoustical properties of solution have to be important parameters in the study of several chemical reactions and in the investigation of molecular inter actions. These Parameters are required to compute the internal pressure, free volume and other thermodynamic quantities. In many industrial applications, liquid mixtures rather than single component liquid system are used in processing and product formulations. Thermodynamic properties of liquid mixtures have been extensively used 4-5 to study the departure of a real liquid mixture from ideality. The same authors have studied the ultrasonic velocity and densities in mixtures of polyacrylamide solution in sodium (meta) silicate and potassium silicate solutions in different concentrations at 303 K 6 . The interaction of sodium dodecyl sulphate (SDS)/poly (vinyl Alcohol) (PVA) solution was studied by ultrasonic velocity measurements. The studies on ultrasonic parameters have become an emerging field in recent years. The objective of ultrasonic studies is to identify the molecular interaction between solute and solvent and to bring about the structural changes associated with them in terms of acoustic properties like sound velocity, adiabatic compressibility and acoustic impedance etc. Ultrasonic velocity, density, viscosity in mixtures of sodium dodecyl sulphate in polyvinyl alcohol was measured over the entire range of composition were studied by the same authors 7 . The present paper deals with further studies carried out by the authors on the ultrasonic behavior of potassium salts in polyacrylamaide solution at different concentrations.
Mixing of all the materials were done manually in the laboratory at room temperature. The fly-ash and aggregates were first mixed homogeneously as shown in fig. 1 and then the alkaline solutions which were made one day before and superplasticiser were added to the mixture of fly ash and aggregates. The Potassium Hydroxide and the sodium Hydroxide solutions were first mixed with each other and stirred to obtain a homogeneous mixture of the solutions before adding them to the solids. The mixing of total mass was continued until the binding paste covered all the aggregates and mixture become homogeneous and uniform in colour A Pan Type concrete mixer that offers mechanical sharing action can be used for obtaining uniform mixture with less effort. Fig. 1 shows a typical dry mixture of solids that was used to make the cube (150x150x150mm) specimens. The fresh geopolymer concrete was used to cast cubes of size 150x150x150mm to determine its compressive strength. The specimens were prepared according to the method followed by Hardjitoet. al.. Each cube specimen was cast in three layers by compacting manually as well as by using vibrating table as shown in fig.3. Each layer received 25 strokes of compaction by standard compaction rod for concrete, followed by further compaction on the vibrating table. The specimens were wrapped by plastic sheet to prevent loss of moisture and placed in an oven. Since the process of geopolymerisation needs curing at high temperature, the specimens were cured at two different temperature 25 0 C and 60 0 C for 24 hours in the oven, as
A remarkable improvement in terms of unconfined compressive strength has been observed by means of alkaline activation process using KOH solution and fly ash class F. This major increase is accounted for the immediate dissolution and uptake of vitreous alumina, occurring on the fly ash particle surface, upon exposure to Potassium hydroxide solution. The phenomenon is best explained by the gradual increase in strength of about six times after seven days induced by weak Al bonds. However, due to the presence of Si species in the internal entity of fly ash and its accompanied low dissolution rate the greatest strength evolution rate is only apparent after around 28 days. The reason behind is that Si bonds more govern the strength increment, which was recorded to be nineteen times greater than that seen by the host soil.
____ 29. amount of solute, in moles, dissolved in one litre of solution ____ 30. concentration expressed as mass of solute in volume of solution ____ 31. concentration expressed as solute volume in solvent volume ____ 32. concentration expressed as solute mass in solvent mass
(conductivity at infinite time) for the conductometric experiments. The conductometric experiments also required correction for hydroxide attack upon the measuring vessel. Both reactions were found to be zero order in hydroxide, to be the only reactions occurring between the platinum complex and the hydroxide for times up to one day, and to involve the formation of an aquo intermediate. The rates for the first hydrolysis were 6. 21 x 10 -5 sec -1 - at 20 °C, 10. 6 x 10 -5 sec -1 at 25°C, and 29.3 x 10 -5 sec -1 at 35°C, with an energy of activation of 18.0 kcal and an entropy of activation of -16 cal/ °K. The rates for the second hydrolysis were 0.17 x 10 -5 sec -1 at 25°C and 0. 50 x 10 -5 sec -1 at 35°C, with an energy activation of 19.1 kcal and an entropy of activation of -21 cal/ °K.
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One potential alternative to Portland cement-based concrete is fly ash-based geopolymer concrete (FGC), which may have the potential to reduce Portland cement usage while mirroring it’s compressive strength and durability characteristics [3,4]. Many studies have shown that FGC can demonstrate beneficial and diverse properties. For example, FGC has shown good resistance against acid and sulfate attack, high early age strength, and good performance in high temperatures [5-12]. It has been proven recently that FGC can achieve high compressive strength in early and final stages. This is also true under ambient curing conditions. Good workability is achieved when additives are incorporated such as Portland cement, calcium hydroxide, or ground granulated blast furnace slag . FGC is an inorganic polymer, which is produced by the reaction of alumino-silicate materials with alkaline solutions and the addition of conventional coarse and fine aggregate. FGC makes use of fly ash, which is a good source of alumino-silicate and is also a prevalent waste material. While the study described is focused on the use of fly ash, other waste materials such as blast furnace slag may also be utilized [14, 15]. FGC is generally agreed to be less deleterious to the environment than Portland cement-based concrete; however, more work to quantify this assertion is warranted.
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Three different neutralizing agents viz. potassium hydroxide, sodium hydroxide and calcium hydroxide and their combinations have been used for study of the sludge generation quantity in waste pickling liquor treatment. Sludge characterization study has been done by XRD and XRF. The following conclusions can be drawn from the study:
Figure 5 and 6 shows the graphical variation of compressive strength with respect to molarity of NaOH solution with solution to fly ash ratio 0.35 and 0.40 respectively.Mix with solution to fly ash ratio 0.4, the rate of increases of strength is similar in case of GPC with temperature curing and GPC with 10% OPC ambient curing. The results of 12,14 and16 molar concentration of NaOH solution produce sufficient strength in case of10 % OPC with ambient curing for both solution to fly ash ratio.
Metal humates have been generally produced from water soluble alkaline humates with the re- lated metal salts. In this study, a new method for the production of barium humate (Ba-HA) from Turkish coal was developed. Insoluble Ba-HA was produced from the result of the extraction of coal directly with barium hydroxide at 120˚C. The effect of the amount of raw materials on the so- lubility and on the content of barium metal was investigated. The pilot plant trial was performed by using 100 kg of coal in one batch based on laboratory results. Ba-HA was characterized by means of FTIR and TGA. The calcination of Ba-HA at the different temperatures and in atmosphere of nitrogen and air was realized to provide the increase in the surface area and the decrease in the chromatographic groups giving yellow color. In terms of the surface area and UV-absorbance val- ues, the calcination condition was selected as the temperature of 350˚C and atmosphere of air. The calcinated Ba-HA was used in the adsorption of some heavy metals. The results show that Ba-HA may have potential to be used as a low cost, natural and eco-friendly adsorbent.
The preparation of classical Unani formulations is based on traditional methods in accordance with the procedures described in classical texts. Lack of modern pharmacopoeial standards for preparation of these formulations results in batch to batch variations and low quality finished products. The increase in the demand for herbal drugs has led to the need for quality standardization of these drugs. The Drug Standardisation Research Unit under the Central Council of Research in Unani medicine, New Delhi is engaged in developing the standards of classical Unani formulations. The Unani polyherbal formulation, Qurs-e-Gulnar known to be effective in the treatment of chronic diarrhoea, has been standardized at the Unit by following modern scientific quality control procedures. The formulation was subjected to various quality control parameters such as organoleptic evaluations (color, odor, taste, and consistency), physicochemical evaluations (loss on drying, total ash, acid insoluble ash, pH of 1 and 10% solution, water soluble matter and alcohol- soluble matter) and HPTLC analysis. The evaluation of contaminants such as heavy metals, aflatoxins, pesticide residues, and microbial contamination was also carried out in the formulation.
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