Use Of Alkaline Solutions Research Articles

Removal of dichloromethane from gas streams by droplet triggered gas discharge

The removal of dichloromethane (DCM) from gas streams by a novel gas discharge reactor triggered by solution droplets was experimentally investigated. The influences of operation parameters such as input energy, gas flow rate, oxygen concentration, droplet dropping frequency, and the solution composition of droplets on the effectiveness of reactor operation and DCM removal efficiency were examined. Experimental results showed that DCM in the gas stream can be effectively degraded, and the removal of DCM decreased with the increase of the initial DCM concentration in the gas stream. With the increase of droplet dropping frequency, the removal of DCM experiences a process from increase to decrease, and the optimal droplet dropping frequency is around 0.5–1 drop·s−1. It was also found that the oxygen concentration in the range of 5–10 % in the gas stream is better for DCM decomposition, and the use of alkaline solution as droplets can effectively improve the removal of DCM. The final gas phase products of DCM degradation were mainly CO2 and O3 with the presence of O2 in the gas stream, and the liquid phase products were chloride (Cl-) and hypochlorite (ClO-) ions.

Innovative cycling reaction mechanisms of CO2 absorption in amino acid salt solvents

Amino acid salt (AAS) solvents with equimolar base (used to obtain the salt) to amino acid (AA) have been well studied for CO2 absorption, however, very little is known about the reactions when more base is applied. This study determined the reaction mechanisms of AAS solvents with base to AA ratio over equimolar and the potential benefits of such solvents for CO2 absorption. The CO2 loading capacity was found to be dictated by the molar concentration of the base and was approximately half of the base applied. The reaction mechanisms were investigated based on the compositions of carbamate, carbonate/bicarbonate, and AA using 13C-quantitative nuclear magnetic resonance (13C qNMR). An innovative cycling reaction mechanism of CO2 absorption was proposed and experimentally confirmed for AAS solvents with base/AA > 1. Besides all steps of the current widely accepted Zwitterion mechanism, this reaction pathway also contains two cycles: 1) The extra base (i.e., OH−) may react with the protonated AA generated during CO2 absorption to form deprotonated AA which further absorbs CO2 to form more carbamate. 2) The carbamate, as a product of reaction cycle 1, undergoes hydrolysis to yield bicarbonate and deprotonated AA, which further absorbs CO2. As a result, high CO2 loadings were achieved. Compared to the use of alkaline solutions like KOH alone for CO2 absorption, AAS solvents with base to AA ratio over equimolar resulted in lower pH and temperature while maintaining high CO2 loading. These innovative cyclic mechanisms will enable advanced CO2 management approaches using AAS solvents with base/AA > 1.

Carbon footprint and water use of alkali-activated and hybrid cement mortars

Cement industry consumes large amounts of water, energy and it is one of the main sources of anthropogenic greenhouse gas emissions. Hence, addressing these environmental constraints leads to a search for alternative mortars to ordinary Portland cement (OPC) replacing the clinker by industrial by-products, such as blast furnace slag and/or fly ash.In this context, alkaline activated materials (AAM) show good mechanical properties comparable to OPC. However, AAM present durability problems against leaching phenomena, and workability problems because of the use of alkaline solutions. Therefore, other alternatives as the hybrid materials (HM) are receiving greater attention.In order to determine if the mechanical properties of hybrid and alkali-activated mortars are indeed comparable to those from Ordinary Portland Cements (OPC), this paper first examines the compressive strength and porosity of an AAM case study from slag and two HM systems, both from slag and fly ash. Moreover, since very little is known about their environmental impacts in terms on water use and carbon footprint they were calculated through the Life Cycle Assessment methodology and compared to those of OPC.Results revealed that the assessed AAM and two HM case studies obtained mechanical properties comparable to those for OPC.The AAM obtained −406.02 kg CO2/m3 while for the hybrids the carbon footprints were −253.26 kg CO2/m3 (HM from slag) and −253.27 kg CO2/m3 (HM from fly ash), proving that partial or total substitution of cement by waste in mortars reduces the carbon footprint of OPC more than 100%. In terms on water footprint, more than a 40% reduction in water use is obtained if HM are used instead of OPC supporting the idea that HM achieve good balance between carbon footprint and water use reductions.

Atomic-Scale Investigation on the Evolution of Tio2-Anatase Prepared by a Sonochemical Route and Treated with NaOH.

To date, the formation mechanisms of TiO2, as well as its heterostructures, have not been clarified. Moreover, detailed research on the transition from a tetragonal anatase phase to the monoclinic phase of the TiO2(B) phase and their interface structure has been quite limited until now. In the present study, we report on the sonochemical synthesis of TiO2-anatase with a crystallite size of 5.2 ± 1.5 nm under different NaOH concentrations via the hydrothermal method. The use of alkaline solution and the effect of the temperature and reaction time on the formation and structural properties of TiO2-anatase nanopowders were studied. The effects of NaOH concentration on the formation and transformation of titanate structures are subject to thermal effects that stem from the redistribution of energy in the system. These mechanisms could be attributed to three phenomena: (1) the self-assembly of nanofibers and nanosheets, (2) the Ostwald ripening process, and (3) the self-development of hollow TiO2 mesostructures.

A novel approach for recovery of manganese from on-site manganese-bearing wastewater

Acid leaching of rhodochrosite will generate electrolytic manganese residue together with emission of carbon dioxide (CO2). Wastewater containing highly concentrated manganese is being generated when treating electrolytic manganese residue. Although carbonate precipitation has been identified as an effective process for manganese removal, this conventional approach is limited by heavy use of alkaline solution and the obtained MnCO3 precipitates have low purity. In this study, an electrolytic manganese plant in Guangxi, China was selected as the study site. CO2 generated from flue gases was carefully chosen as the potential reagent for the recovery of manganese from wastewater. The effects of operational modes including batch mode, batch mode with external recirculation, continuous mode and continuous mode with external recirculation on the performance of wastewater treatment were systematically investigated in pilot scale, and the obtained precipitates were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and the thermal gravity-differential thermal analysis (TG-DTA). It was found that batch mode with external recirculation is optimal as over 99.99% of Mn2+ can be selectively recovered from Ca2+, Mg2+ and Mn2+-containing wastewater by bubbling with CO2, and the obtained MnCO3 precipitates met the industrial standard in China (grade I). The pH value of the effluent is 6.6 and the concentration of Mn2+ is 1.0 mg L−1, which can be recycled within this system. The present study provides a sustainable technique to solve the problems of treating industrial wastewater containing heavy metals.

Alkali-activation of fly ash and cement kiln dust mixtures for stabilization of demolition aggregates

Utilization of industrial by-products such as cement kiln dust (CKD) and fly ash (FA) for increasing the strength and stiffness of demolition waste aggregates can be an optimal and sustainable solution for reducing the carbon footprint of the construction activities. Furthermore, this approach of incorporating waste materials as construction materials will also reduce the rapid depletion rate of natural resources. This research presents an optimization, by means of evaluating combinations of CKD + FA blends to utilize the rich source of calcium and silica and alumina in these by-products. The impact of sample preparation method is investigated. The use of alkaline solutions facilitates the progression of activation process in room temperature. Recycled Concrete Aggregate (RCA), Crushed Brick (CB) and Reclaimed Asphalt Pavement (RAP) are three major components of the demolition waste stream and were used as the parent materials in this research for assessment of the efficiency of stabilization process. The durability of the stabilized materials under repeated loading was investigated. In addition, the resilient modulus of the stabilized materials were compared with the empirical models to assess the impact of confining stress and deviatoric stress on the moduli of the mixtures. The optimum ratio of FA:CKD of 50:50 showed the highest performance. The research indicates that alkali-activation of 15%CKD and 15%FA blended with C&D aggregates provided the optimum blend for the usage of these wastes as construction materials.

Clearing and dissecting insects for internal skeletal morphological research with particular reference to bees

A detailed protocol for chemical clearing of bee specimens is presented. Dry specimens as well as those preserved in liquid media can be cleared using this protocol. The procedure consists of a combined use of alkaline solution (KOH or NaOH) and hydrogen peroxide (H2O2), followed by the boiling of the cleared specimens in 60–70% EtOH. Clearing is particularly useful for internal skeletal morphological research. This procedure allows for efficient study of internal projections of the exoskeleton (e.g., apodemes, furcae, phragmata, tentoria, internal ridges and sulci), but this process makes external features of the integument, as some sutures and sulci, readily available for observation as well. Upon completion of the chemical clearing process the specimens can be stored in glycerin. This procedure was developed and evaluated for the preparation of bees and other Apoidea, but modifications for use with other insect taxa should be straightforward after some experimentation on variations of timing of steps, concentration of solutions, temperatures, and the necessity of a given step. Comments on the long-term storage, morphological examination, and photodocumentation of cleared specimens are also provided.

Features of the Leaching of Lead from Slurry-Production Middlings by Industrial Complexons

The research discussed in this article was performed to make the processing of sludge formed in the electrolytic refining of copper more efficient. Results are presented from studies involving selection of the reagent regime and optimization of the conditions for leaching lead from tailings formed in the flotation concentration of decopperized sludge. The main components of the raw materials that were studied: lead oxysulfate (up to 60%) and oxidized complex compounds of antimony (up to 30%). Industrial complexons were proposed for use as the solvents. The tests showed that preference should be given to the use of alkaline solutions of oxyethylenediphosphoric (OEDP) acid. The kinetic features of the process were studied by using a method which employs a rotating disk of synthetic tribasic lead sulfate. The experimental rate constant for the leaching of lead in an OEDP solution reaches 6·10−6 g-ion/(cm2·sec). It was established that the process is diffusional in nature and that the effect of temperature is negligible. A large-scale balance experiment involving the removal of lead from flotation tailings was performed in a laboratory. The experiment established that the level of recovery of lead in an alkaline solution of OEDP reaches 85% and that the other important components of the sludge (antimony and noble metals) remain almost entirely in the undissolved residue.

The cost of alkaline solutions in ambulatory hemodialysis: an analysis about wasteful from the processes control.

There are few studies about costs of inputs used in hemodialysis and among these expenditures, the compounds that make up the dialysate are one of the values considered as representative of this therapy. However, there aren't costs studies that guiding solutions. The objective of this article is discuss whether there is wasteful of alkaline solutions in ambulatory hemodialysis and hence the possibility of reduction in cost from the standardization process simulation of establishment of dialysate flow in periods between shifts in hemodialysis outpatients. Starting from an observational analytic, a simulation was performed twenty case scenarios, which ten cases established by standardizing processes control on the dialysate flow in recession. The combination of data was performed using as a basis the prices of three suppliers of alkali liquid or powder. It was observed among the scenarios with standardized processes, ranging between 7.7% and 33.3% savings in the alkaline solution cost (powder or liquid), by reducing waste. It is possible to restrain the wasteful use of alkaline solutions, both powder and liquid. Consequently, its cost from the patterning on reducing the flow of dialysate during the intervals between shifts observed in the outpatient hemodialysis. However, these results are conditional upon the commitment of health professionals, mainly to supervision exercise and control of activities in quality function deployment.

Graphene oxide modified non-noble metal electrode for alkaline anion exchange membrane water electrolyzers

This paper reports the performance of a graphene oxide modified non noble metal based electrode in alkaline anion exchange water electrolyzer. The electrolytic cell was fabricated using a polystyrene based anion exchange membrane and a ternary alloy electrode of Ni as cathode and oxidized Ni electrode coated with graphene oxide as anode. The electrochemical activity of the graphene oxide modified electrode was higher than the uncoated electrode. The anion exchange membrane water electrolyzer (AEMWE) with the modified electrode gave 50% higher current density at 30 °C with deionised water compared to that of an uncoated electrode at 2 V. Performance was found to increase with increase in temperature and with the use of alkaline solutions. The results of the solid state water electrolysis cell are promising method of producing low cost hydrogen.

Proceso tradicional de aderezo de aceitunas verdes de mesa. Racionalización del cocido

In order for olives of the Manzanilla variety to be produced as Spanish-style, they require a previous storage period before their alkaline treatment with NaOH. This holding time prevents the breakage and shedding of the fruit epidermis, but at the same time, causes an increase in the number of olives with surface blemishes and, consequently, loss in product quality. The objectives of this work were to investigate, at industrial scale, different alternatives to the holding period; specifically, the use of low-concentration alkaline solutions before the real alkaline treatment, and the use of alkaline solutions at low temperatures for this alkaline treatment. Basic parameters of the fermentative processes carried out in every treatment were monitored, and commercial quality of the final product was ascertained. The results indicate that both modifications are alternatives to the traditional treatment, and the products obtained applying these modifications have the same or higher quality than those obtained by the traditional process.

Hierarchically structured meso-macroporous aluminosilicates with high tetrahedral aluminium content in acid catalysed esterification of fatty acids

A simple synthesis pathway has been developed for the design of hierarchically structured spongy or spherical voids assembled meso-macroporous aluminosilicates with high tetrahedral aluminium content on the basis of the aqueous polymerisation of new stabilized alkoxy-bridged single molecular precursors. The intimate mixing of an aluminosilicate ester (sec-BuO)2–Al–O–Si(OEt)3 and a silica co-reactant (tetramethoxysilane, TMOS) with variable ratios and the use of alkaline solutions (pH 13.0 and 13.5) improve significantly the heterocondensation rates between the highly reactive aluminium alkoxide part of the single precursor and added silica co-reactant, leading to aluminosilicate materials with high intra-framework aluminium content and low Si/Al ratios. The spherically-shaped meso-macroporosity was spontaneously generated by the release of high amount of liquid by-products (water/alcohol molecules) produced during the rapid hydrolysis and condensation processes of this double alkoxide and the TMOS co-reactant. It has been observed that both pH value and Al–Si/TMOS molar ratio can strongly affect the macroporous structure formation. Increasing pH value, even slightly from 13 to 13.5, can significantly favour the incorporation of Al atoms in tetrahedral position of the framework. After the total ionic exchange of Na+ compensating cations, catalytic tests of obtained materials were realised in the esterification reaction of high free fatty acid (FFA) oils, showing their higher catalytic activity compared to commercial Bentonite clay, and their potential applications as catalyst supports in acid catalysed reactions.

Reaction of aluminium with alkaline sodium stannate solution as a controlled source of hydrogen

The addition of an alkali has been identified as a simple but effective approach for promoting aluminium (Al)/water (H2O) reactions. However, the use of alkaline solution causes problems with corrosion of system apparatus. We herein report a novel method that can simultaneously address the Al/H2O reaction kinetics and alkali corrosion problems. Our study found that a combined usage of sodium hydroxide (NaOH) and sodium stannate (Na2SnO3) can dramatically improve the hydrogen generation kinetics of the Al–H2O system. Furthermore, the addition of a small amount of Na2SnO3 causes a remarkable decrease of NaOH concentration, which is required for achieving favorable system performance. The factors influencing the hydrogen generation performance of the system were investigated. In the preliminary mechanistic study, the solid samples that were collected at different reaction stages were examined by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Our study showed that the most likely mechanism for the promoting effect of Na2SnO3 is the in situ deposition of metallic Sn particles on the Al surface, which act as local inhibitors of the repassivation of Al.

Mechano-chemical activation: an ecological safety process in the production of materials to stone conservation

The aim of this work is the assessment of the possibility to produce geopolymeric materials for the specific use in the field of consolidation of stone materials or as restoration mortars, through mechanochemical activation of two solid precursors, quartz and kaolin. These starting materials were modified by grinding at different times and then the degree of reactivity of the obtained products was verified by studying the changes induced by the mechanical treatment on the crystalline structure and by determining the specific surface. Moreover the solubility and kind of alkaline solutions classically used for the production of geopolymeric materials (NaOH and KOH) was investigated together with other aqueous solutions at variable pH. The mechano-chemical activation process can achieve the result to reduce the use of alkaline solutions as activators of the starting raw materials in the production of consolidating solution for monument stone materials and to utilise natural materials in the production of restoration mortars compatible with the substrates to be restored.

Electrodeposition of In–Se and Ga–Se Thin Films for Preparation of CIGS Solar Cells

An approach was developed for electrochemical codeposition of In-Se and Ga-Se films with high repeatability and controllable In/Se and Ga/Se molar ratios to prepare precursor layers for copper indium gallium diselenide (CIGS) film formation by two-stage processes. Full potential of complexation was used for the first time by using aqueous electroplating solutions containing complexing agents at alkaline regime. It was found that tartrate and citrate were suitable complexing agents to solubilize In and Ga ions at high pH, respectively. Because no appreciable complexation of Se occurred, Se reduction potential could be independently controlled by the amount of dissolved Se. Use of alkaline solutions also reduced hydrogen bubble generation and related defects.

Chromatographic Determination of the Effect of Storage on Lycopene

A reverse-phase high-performance liquid chromatography (HPLC) method for the determination of lycopene in an alkaline lipid phase is described, and pigment stability in stored tomato sausage is reported. To avoid and replace the use of nitrite, lycopene from tomato products is added to minced meat and a tomato sausage with natural color is produced. Tomato sausage with and without nitrite were smoked in a smoking compartment and stored (4 degrees C and 8 degrees C) for 25 and 17 days, respectively. Among other factors, the quality of the tomato sausage depends on stability of lycopene during process and storage. Lycopene, being lipophilic, is extracted together with the polar and neutral fat in food. Efforts to purify lycopene from the fatty content will result in loss of pigment. The triacylglycerides obstruct the detection of lycopene by spectrophotometry or by HPLC with diode-array detection. To solve this problem, the triacylglycerides are hydrolyzed to free fatty acids just before analyzing lycopene on a column tolerating alkaline samples. At the end of the storage, loss of pigment in the sausage without nitrite was 26% stored at 4 degrees C and 19% at 8 degrees C. Corresponding results for the sausage with nitrite added as well as tomato paste show the loss of pigment is 20% and 45%. For each type of fatty food extracted, it is important to minimize the use of alkaline solutions because the HPLC equipment may be susceptible to alkaline conditions.

Properties of the system H 2ONaOHZnO part I: Density, velocity and boiling point

The best alternative for improving the energy efficiency of the conventional zinc electrowinning process is to use alkaline solutions. For this process, since the use of alkaline solutions means that higher current densities can be used, more heat needs to be removed from the cells to avoid the electrolyte boiling and zinc redissolution may become important at high temperatures. Control of the solution alkalinization is essential and this has the effect of increasing the cell voltage and may favor corrosion of the cell components or zinc product. Modelling of alkaline electrowinning cells is not possible, however, since values for the chemical, electrochemical and physical properties are not available. The viscosity and density of aqueous solutions of sodium hydroxide and zinc oxide (solutions prepared at 303 K with 160–280 g/l NaOH and 3–50 g/l Zn) were determined over a range of temperatures from ambient to boiling point. Boiling point values were also determined. Correlations are given for the most common units of concentration (molar, molal and weight percentage).

Observations on the treatment of severe diabetic ketosis.

SummaryA series of 32 patients with severe diabetic ketosis treated by us during 1956–1957 has been compared with a similar group of 67 patients admitted to the Alfred Hospital, Melbourne, between 1952 and 1955.This comparison has shown that the mortality has decreased during 1956–1957. The reasons for this have been analysed and discussed, and the rationale for the present regime of treatment is presented.It is concluded that the reduction in mortality has been due to several factors, which include the following: (i) the management of diabetic ketosis by one unit; (ii) the use of alkaline solutions at the commencement of treatment; (iii) the administration of potassium salts early in treatment; (iv) a reduction in the severity of the condition on the patients' admission to hospital.The need is stressed for educating patients and practitioners in the early recognition of this disorder so that mortality may be further reduced.

A Machine for Cleaning Motion-Picture Film

A machine is described for the cleaning of motion-picture film by the spray application of water containing a detergent. Following the spray wash, rinse sprays and an Ott-type squeegee provide additional cleaning action prior to drying. The film is wet for such a short time that little moisture penetration occurs, and only a brief drying time is necessary. The film is not subjected to physical contact with wipers or buffers, nor are other scratch or abrasion hazards present on the machine. Surface deposits, loose dirt, and embedded dirt normally encountered on motion-picture film are effectively removed. Coatings of some alkali-soluble lacquer used on motion-picture film are effectively removed by the use of alkaline solutions in the sprays in place of the detergent solution. The results of experimental cleaning trials have shown this machine to be particularly satisfactory for color films. Black-and-white films may be subject to density losses when rewetted and dried more than 10 times.

A COMPARISON OF GLUTENIN AND GLIADIN PREPARED FROM ONE FLOUR BY VARIOUS METHODS

Gliadin and glutenin were prepared from gluten of hard red spring wheat flour by five different methods and analyzed by the Van Slyke procedure. The gliadin preparations gave very similar results, indicating that differences in manipulation have little effect on this protein. The glutenin preparations showed very great differences in nitrogen distribution, the greatest being in ammonia nitrogen and in basic nitrogen. There is considerable evidence that these two nitrogen fractions tend to be inversely proportional. This is particularly applicable to preparations made by methods involving use of alkaline solutions. Glutenin isolated by use of Blish and Sandstedt's acetic acid method, using 0.007 N acid appeared to be purer than the other preparations and contained the highest percentage of ammonia nitrogen. This protein, when dissolved in 0.025 N sodium hydroxide solution and allowed to stand for one week, lost 4.8% of its nitrogen in the form of ammonia, but the basic fraction was unchanged. It seems likely that any method for isolating glutenin involving use of alkaline solutions would involve loss of nitrogen in the course of the preparation and the nitrogen distribution obtained by the Van Slyke analysis would therefore be in error. The use of very dilute acetic acid is recommended but exposure to even dilute solutions of the strong alkalies should be rigorously avoided in the preparation of glutenin.