Use Of Alkali Research Articles

A facile approach to the synthesis of 3,4-dihydro-2H-benzo[4,5]imidazo[2,1-b][1,3,4]thiadiazines

An efficient approach to the synthesis of novel 2,3-diaryl-3,4-dihydro-2H-benzo[4,5]imidazo[2,1-b][1,3,4]thiadiazines via a base-catalyzed intramolecular cyclization of 2-arylmethylthio-N-arylidene-1H-benzo[d]imidazol-1-amines has been developed. The use of alkali is critical for the annulation of the thiadiazine ring. In the absence of strong bases, the starting compounds undergo deamination with elimination of benzonitrile and formation of 2-arylmethylthiobenzimidazoles.

Investigation of solid waste generation rate and biogas production

Anaerobic Digestion (AD) of organic waste is one of the most promising processes and is the ideal solution for the disposal of organic waste (OW) and at the same time, the production of methane gas which may be used as a sustainable energy resource. An anaerobic biodigester with a volume of (20) liters has been used to digest organic waste and to trace the changes that occur during the AD process. Operating parameters such as temperature, pH, total solids, and volatile solids (TS, VS) have been measured which have a significant impact on the rate and quality of biogas production. Experiments on anaerobic biodegradation of OW-SS were monitored under mesophilic conditions (temperature 37 °C, retention time 30–31 days). The pH value varied between (4.2–5.8) for OW-SS. During 30 days of the detection period, the maximum methane production (corrected) occurred on day 21 which was equal to 254.3-ml. The cumulative volume of the produced methane was recorded as (3409 ml), OW-SS, and these results were corrected to the standard conditions, where after correction, it became (2929 ml). The highest rate of methane concentration was estimated at (52 %) for OW-SS, while the rate of decrease in the TS and VS was (54 %, and 45 %), respectively. It is recommended to examine the changes that occur if a larger digester is used than the one used in the current study, such as 50 L, 100 L …. Etc. To compare the data obtained in this study with the results of larger digestions to allow for the opportunity to build anaerobic digesters at the plant level with the benefit of renewable energy production. It is also recommended to investigate the impact of some types of pretreatments on biogas production such as the use of alkali, enzymatic, ultrasonic treatment or acid ton the solid waste feed.

Древесно-композитные плиты с низким коэффициентом линейного теплового расширения

A number of industries require materials with a low coefficient of linear thermal expansion (CLTE), in particular, in the production of satellite spherical antennas. The latter are formed from composites containing carbon fibers and synthetic resins. The composition is cured by heating up to 180 °C. This leads to a thermal expansion of the mold and a change in the geometric characteristics of the product. Therefore, specific requirements are imposed on the materials for making molds. The high cost of special materials used for molds determines the need to search for other materials with a low CLTE. Wood is a possible solution to this problem. Its CLTE along the fibers is less than that of the vast majority of materials, and is approximately 3 ‧ 10-6 K–1, which is comparable to special materials. However, the expansion of wood across the fibers is much higher than the longitudinal one, which excludes the use of solid wood. Anisotropy can be reduced by creating a composite in which the fibers are uniformly oriented in all structural directions, bringing the value of wood expansion across the fibers closer to the value of expansion along the fibers. The traditional approach to producing wood composites, based on the use of synthetic adhesives, fails to achieve a noticeable reduction in thermal expansion due to the high CLTE of adhesives The use of boards made of hydrodynamically activated wood particles without binders is promising. Three series of experiments have been carried out: with varying the density of the boards, preliminary thermal modification of the original wood and the use of alkali during hydrodynamic processing. The thermal expansion study has been carried out using the NETZSCH DIL-402 C induction dilatometer in dynamic mode with a heating rate of 2 K/min. It has been established that thermal expansion increases with increasing density.The average CLTE at a density of 950 kg/m3 is 12 ‧10–6 K–1 and at a density of 1,100 kg/m3 it is 17‧10–6 K–1. At a comparable density, the thermal expansion of boards without binders is significantly lower than that of fiberboards (MDF). Preliminary thermal modification of wood does not significantly affect the CLTE of the boards. The use of alkali in the hydrodynamic treatment also has no effect.

Shear wave velocities to monitor curing evolution of soils treated with alkali activated binders

The use of alkali activated binders for soil improvement has been significantly increased in the past decade indicating a significant interest in the use of alternative low carbon binders. The optimisation and preliminary characterisation of the mixtures is usually addressed with destructive tests to evaluate strength such as unconfined compression strength tests. Although important and necessary, these tests require a significant number of specimens, especially when monitoring the strength evolution with time due to curing. Seismic wave velocity measurements, in particular S wave velocities, allow a fast evaluation of the elastic shear stiffness with time avoiding specimens’ failure. This is even more important in soils stabilised with alkali activated binders, since its strength and stiffness evolution with time is generally very long, keeping increasing far beyond the 28 days mark usually assumed in soils improved with Portland cement. In this paper, the evolution of the elastic stiffness with time for different soils treated with alkali activated binders is presented. The compilation of the results for different soils and mixtures, allowed a clear definition of the typical trend and range.

Combined method of impact on layered-heterogeneousn formation based on in-situ steam generation

This article discusses the combined method of influencing a layered-heterogeneous reservoir. In-situ steam generation (IPSG) is used as the main method, which in turn can be considered a combined technology of hot water injection and in-situ combustion. In order to improve the efficiency of the IPSG, it is proposed to inject a slug of an alkali solution (NaOH). The main mechanism in the application of IPSG is thermal interference between layers of different permeability. The use of alkali allows us to use its positive properties. The use of alkali allows us to use its positive properties. Such as lowering the surface tension at the boundary of the oil solution of alkali, the formation of an emulsion. The formation of an emulsion in a high-permeability layer contributed to an increase in the pressure drop in it and, accordingly, changed the direction of the fluid flow. Most of the injected water-air mixture began to flow into the low-permeability layer. Thus, the effectiveness of the impact on the formation was increased. The effect of alkali solution concentration on oil displacement from a layered-heterogeneous reservoir is estimated. The proposed technology made it possible to increase the coverage of the layered formation by the process and, accordingly, increase the oil recovery factor. Experiments were carried out for two oils with different viscosities: 86 mPa.s and 510 mPa.s.

New Composite Materials Based on Chitosan Films Reinforced with Chitin Nanofibrils for Cosmetic Application

Bioactive biodegradable chitosan films containing chitin nanofibrils have been developed for use as face masks in cosmetology. It was found that thermal modification of chitosan films promotes the transformation of the polymer into insoluble form without the use of alkali or aldehydes. The structure and properties of the films were studied by IT spectroscopy, atomic force microscopy, thermogravimetric analysis, and X-ray structural analysis. Analysis of infrared (IR) spectra showed that the addition of nanofibrils accelerates the process of thermal transformation in the composite films. This is apparent from the observed increase in the intensity ratio of 1030 cm−1\1580 cm−1 peaks in the spectrum of the thermally treated film (as compared to the spectrum of the initial sample and the spectrum of a chitosan film without chitin nanofibrils). The prepared composite films containing chitin nanofibrils possess improved mechanical characteristics: tensile strength 99 MPa and tensile strain 14%. The tetrazolium bromide (MTT) test revealed good viability of human dermal fibroblasts cultivated in the presence of the conditioned medium obtained after incubation of all types of films in the nutrient medium. The used process of thermal modification of chitosan and composite films (which is efficient and environmentally safe) allows one to prepare bioactive materials for applications in medicine and cosmetology.

Surfactant formulation development for shallow reservoirs with high clay content

Sandstone reservoirs with high clay content can potentially adsorb large amounts of surfactants making the chemical flood processes unattractive. The objective of this work was to develop an alkaline-surfactant-polymer (ASP) process for a shallow, clayey sandstone reservoir to minimize surfactant retention. The phase behavior study was conducted to identify commercially available surfactants that display ultralow interfacial tension behavior. The selected surfactant formulations were tested in tertiary ASP core floods in outcrop and reservoir rocks. Many surfactant formulations were identified which gave ultralow IFT, but the formulation with only one surfactant (at 0.5 wt% concentration) in presence of one co-solvent was selected for core floods. The cumulative oil recovery was in the range of 92–96% of the original oil in place (OOIP) in the core floods. The surfactant retention was low (0.15 mg/gm of rock) in spite of the high clay content due to the use of alkali. The study showed that 0.5 PV of ASP slug and 2700 ppm of the polymer were required to make the flood effective. Injection of the ASP slug immediately after the field brine flood with divalent ions did not cause any plugging or adverse effect. The novelty of this work lies in designing ASP formulations with a single surfactant and reducing the residual oil saturations to ∼3% in field cores along with low surfactant retention. This paper illustrates a workflow to identify the chemical formulation, chemical concentrations and slug sizes.

Adsorption of surfactant during chemical enhanced oil recovery

AbstractSurfactant is extensively used as chemicals during chemical enhanced oil recovery (CEOR) process. Effectiveness of surfactant CEOR process depends on several parameters like formation of micro emulsion, ultra‐low interfacial tension (IFT) and adsorption of surfactant. First two parameters enhance the effectiveness while the last parameter reduces the effectiveness. Micro emulsions are highly desirable for CEOR due to its low interfacial tension (IFT) value and higher viscosity. In this research the size of the emulsions were studied with particle size analyzer to study the liquid–liquid absorption process and the entrapment of oil drops inside surfactant drop. Initially, the average surfactant drop size was found to be 100 nm, after mixing the surfactant slug with reservoir crude, the size was increase up to 10 times. It signifies the formation of micro emulsion between surfactant and oil. Another attempt was done in this research to study the adsorption mechanism of surfactant on reservoir rock. The process of adsorption was studied by Langmuir and Freundlich isotherm to understand the adsorption phenomena. In this study, it was found that the adsorption follows Freundlich isotherm and the adsorption phenomena was chemical for surfactant flooding process. In chemical adsorption phenomena, the rate of adsorption is high because, surfactant molecules are adsorbed layer after layer by the rock surface. Use of alkali along with surfactant reduces adsorption of surfactant since, alkali blocked the active clay sites before interacting with surfactant and hence the adsorption isotherm was found to be Langmuir and phenomena was physical adsorption.

Структурно-морфологические свойства вторичного волокна из влагопрочного сырья при мягком размоле. Часть 1. Характеристика волокон

The efficient use of papermaking potential of secondary fiber by gentle refining of recycled pulp is one of the basic principles for the recovered paper stock preparation. The use of mild refining modes for recycled fiber is more important in the case of wetstrength paper than for conventional waste paper. This is due to the fact that recycled fiber is weakened by hard conditions of wet-strength paper repulping, in particular, long repulping time, elevated temperature, the use of alkali and oxidizers. The study aims at evaluating the changes in the morphological characteristics of secondary fiber during gentle low-consistency refining of recycled pulp. The analysis of the secondary fiber morphological characteristics was carried out in two complementary directions, i.e. the analysis of the fibers (part 1) and the analysis of the fines (part 2). Recycled pulp (RP) was obtained from commercial wetstrength tissue paper consisting of 100 % bleached softwood kraft pulp (BSKP) made of pine (Pίnus sylvéstris L.). The wet-strength paper repulping was performed at 60 °C in three ways, namely, repulping with sodium hydroxide (indicated as RP(NaOH)), repulping with sodium hydroxide and sodium persulfate (RP(NaOH + Na2S2O8)), and finally repulping with sodium hydroxide and potassium monopersulfate (RP(NaOH + KHSO5)). Secondary fibers as well as primary fibers of BSKP had similar length distribution before and after gentle refining. Mean fiber length after first recycle reduced by 5–6 %. The calculated values of the fibershortening index showed that fiber cutting practically does not occur during gentle refiningof the recycled pulps. The increase in the refining degree of the pulps is mainly explained by the fibrillation of secondary fibers, rather than the formation of a large amount of fines. Secondary fibers obtained from the wet-strength paper have a high slenderness ratio ((L/W)l from 66.3 to 66.5 and (L/W)w from 83.6 to 84.3; where L – length, W – width) corresponding to pulp with good papermaking potential. The results showed that low-consistency gentle refining of the recycled pulp obtained by accelerated persulfate and monopersulfate repulping of the wet-strength paper leads to fiber straightening. The overall increase in the shape factor of secondary fibers was achieved due to a combination of accelerated repulping of the wetstrength waste paper (by ~ 60 %) and gentle refining of the pulp (by ~ 40 %).

STUDY OF ACID RESISTANCE OF HYBRID ALKALI ACTIVATED NORMAL HARDENING CEMENTS

One of the reason of loses of main production sources nowadays for chemical, food and special industries is the degradation of equipment and constructions caused by acid corrosion. Traditional materials are characterized by various disadvantages, among them: high costs of the material, low water resistance, hard technology and danger for the personal.
 One of the ways to obtain acid resistant material is the use of alkali activated cements, which are known are the resistant to the aggressive environments. Increasing of acid resistance is possible by reducing of system basicity level.
 The presented studies have proved the possibility to obtain acid resistant materials, able to be hardening in normal condition, so far as possibility to partial replacement of the conditional alumina silicates by alumina silicates with technogenic origin, namely, red mud from alumina production under Bayer process. Reducing of basicity level make it possible to increase corrosion resistance coefficient up to 0.88. Also thus a way material became more ecologically friendly and lowering the cost of material.

Potential use of alkali activated clay from common deposit for removal of methylene blue dye

Potential use of alkali activated clay from common deposit for removal of methylene blue dye

Influence of Canadian beef quality grade and method of intramuscular connective tissue isolation on collagen characteristics of the bovine longissimus thoracis

Forty-eight bovine longissimus thoracis (LT) muscles, twelve from each Canada quality grade (Canada A, AA, AAA, and Prime) were used to test the hypotheses that intramuscular total collagen and collagen solubility decreased with increased quality grade and intramuscular fat, and that alkali isolation of intramuscular connective tissue (IMCT) does not reduce Ehrlich Chromogen (EC) or Pyridinoline (PYR) concentrations. Total collagen increased as intramuscular fat increased when estimated using lyophilized meat but did not when estimated using isolated IMCT. Beef quality grades and their concomitant intramuscular fat did not affect collagen heat solubility or mature collagen cross-link concentrations. Use of alkali for IMCT isolation did not degrade EC or PYR collagen cross-links, suggesting it is an excellent method for isolating IMCT for further characterization. The EC cross-link was most related to WBSF in the LT muscles from youthful cattle (< 30 months), confirming that EC is the most influential collagen cross-link on WBSF of low IMCT content muscles when cattle are young.

Comparison of acid and alkaline pre-treatment of lignocellulosic materials for biogas production

This work deals with the study of a pre-treatment method promoting degradability of lignocellulosic biomass and hence biogas yield therefrom, as this material is challenging to decompose due to its structure. The investigated pre-treatment methods are hydrolysis of the material in NaOH (0.5% and 5%) and H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; (0.5% and 5%) at temperatures of 90–100 °C for 2 h. This work aimed to compare the effects of these pre-treatment methods on the lignocellulosic composition of maize waste (maize stalks, leaves and cobs), rapeseed straw and wheat straw and the biogas yields from its subsequent anaerobic digestion. Pre-treatment by 0.5% NaOH increased the biogas production the most (by 159% for rapeseed straw, 240% for wheat straw and 59% for maize waste) also the degrees of solubilisation was higher, at the same time the proportions of total organic carbon (TOC) in the solid component appear to be sufficiently high, it could be assumed that there has been sufficient disturbance of the material structure. Alkaline methods have proven to be more suitable compared to acid pre-treatment methods, also the use of alkali with a lower concentration has shown to be more efficient, which is more advantageous for use in practice from an environmental and economic point of view.

Application of biochar and alkalis for recovery of sour anaerobic digesters

Commercial digesters handling complex waste and organic overloading often encounter unbalanced conditions or failures. With limited studies on the digester recovery from an industry-based waste stream, a complex and high-strength digestate containing up to 79 g COD l−1 from acidified commercial digester was investigated for biochar and alkaline treatments. The addition of biochar and calcium hydroxide successfully decomposed excessive volatile fatty acid up to 18.9 ± 2.5 g l−1 and resumed methane production. The maximum methane yield was obtained from the digester amended with biochar (373.4 ± 6.0 ml g COD−1), followed by calcium hydroxide (350.1 ± 2.5 ml g COD−1). Calcium hydroxide treatment showed a shorter lag phase than the biochar by 44%. Methane production could not be recovered by using sodium hydroxide or untreated digester. This study provides a strategic approach to justify the use of alkalis for restoring sour digesters from industry-based waste streams.

Sorption of Nanomaterials to Sandstone Rock.

We investigated the interaction of silica nanostructured particles and sandstone rock using various experimental approaches, such as fluid compatibility, batch sorption and single-phase core-floods. Diol and polyethylenglycol (PEG) surface-modified nanostructured silica materials were tested using two brines differing in ionic strength and with the addition of sodium carbonate (Na2CO3). Berea and Keuper outcrop materials (core plug and crushed samples) were used. Core-flood effluents were analysed to define changes in concentration and a rock’s retention compared to a tracer. Field Flow Fractionation (FFF) and Dynamic Light Scattering (DLS) were performed to investigate changes in the effluent’s size distribution. Adsorption was evaluated using UV–visible spectroscopy and scanning electron microscopy (SEM). The highest adsorption was observed in brine with high ionic strength, whereas the use of alkali reduced the adsorption. The crushed material from Berea rock showed slightly higher adsorption compared to Keuper rock, whereas temperature had a minor effect on adsorption behaviour. In core-flood experiments, no effects on permeability have been observed. The used particles showed a delayed breakthrough compared to the tracer, and bigger particles passed the rock core faster. Nanoparticle recovery was significantly lower for PEG-modified nanomaterials in Berea compared to diol-modified nanomaterials, suggesting high adsorption. SEM images indicate that adsorption spots are defined via surface roughness rather than mineral type. Despite an excess of nanomaterials in the porous medium, monolayer adsorption was the prevailing type observed.

Enhancement of oil recovery by surfactant-polymer synergy flooding: A review

With the depletion of conventional resources, it is necessary to enhance the recovery of remaining oil. The tertiary oil recovery chemical flooding is the most promising for enhanced oil recovery (EOR). The use of alkali in chemical flooding produces fouling with the formation, which brings new challenges to chemical flooding EOR. So, alkali-free surfactant-polymer (SP) flooding is used as a new solution for EOR. The polymer makes the displacing fluid have a high viscosity and increases the swept volume. The surfactant can decrease the interfacial tension and emulsify the crude oil while the displacing fluid reaches the corresponding area. The synergistic effect of the two is more conducive to the recovery of the remaining oil. As a result, SP flooding is a more practical approach to enhance oilfield EOR. The research status of several surfactant and polymer types for EOR is reported in this work. According to the study, complex and anionic surfactants are better for EOR. For difficult formations, SP flooding is more suited because of the presence of polymers. Additionally, study analysis demonstrates that SP flooding and alternative polymer injection, when employed at the same cost, can enhance EOR and assist in resolving issues brought on by low oil prices.

Synthesis of a Cellulose-Co-AMPS Hydrogel for Personal Hygiene Applications Using Cellulose Extracted from Corncobs.

Cellulose-based hydrogels were prepared by the extraction of cellulose from corncobs after the removal of lignin and hemicellulose with the use of alkali–acid treatment. Acrylate-based hydrogels presently available for personal hygiene uses are not biodegradable. In this study, a biodegradable cellulose-co-AMPS personal hygiene hydrogel was synthesized. The hydrogel was synthesized by graft co-polymerization of 2-acrylamido2-methyl propane sulfonic acid onto corncob cellulose by using potassium persulfate (KPS) as an initiator and borax decahydrate (Na2B4O7·10H2O) as a cross-linking agent. Structural and functional characteristics of the hydrogel such as swelling measurements, antimicrobial tests, FTIR spectra and thermogravimetric analysis were done. The hydrogel showed an average swelling ratio of 279.6 g/g to water and 83.3 g/g to a urine solution with a 97% gel fraction. The hydrogel displayed no clear inhibition zone and did not support the growth of bacteria, Gram-positive or -negative. The FT-IR spectra of the hydrogel confirmed the grafting of an AMPS co-polymer onto cellulose chains. The thermal properties of the hydrogel showed three-step degradation, with a complete degradation temperature of 575 °C.

Chemical burns of the esophagus in children of Kyrgyzstan:10-year analysis of prevalence and cause

Introduction and Aim:In Kyrgyzstan, there are still no studies on the prevalence of chemical burns of the esophagus in children, and there are also few studies aimed at studying the causative agents. The present study aimed to assess the prevalence of burns of the esophagus due to the accidental use of various chemicals by children and the chemical composition of cauterizing substances over a 10-year period of admission of children to the clinic.&#x0D; Materials and Methods:An analysis of 1081 cases of chemical burns of the esophagus in children who received inpatient treatment for the period 2011–2020 is presented.&#x0D; &#x0D; Results:In our study, caustic substances were used more often by boys (56.9%) than girls (43.1%), most of the children were under the age of 3 years. There is a tendency for an annual increase in chemical burns of the esophagus. Among the causal factors, there is an increase in the use of alkalis, which are part of the cleaning agents for dishes and plumbing pipes - Krot; recently, the cleaning agent for cauldrons - Aurora is gaining momentum.&#x0D; Conclusion: The emerging situation indicates not only the need for further medical research in this area, but also the tightening of requirements for the packaging and use of household chemicals, and the solution of this problem at the state level.

Properties of lightweight alkali activated controlled Low-Strength material using calcium carbide residue – Fly ash mixture and containing EPS beads

This research aims to use of alkali activated binder containing expanded polystyrene (EPS) beads for producing lightweight controlled low strength materials (CLSM). Sodium hydroxide (NH) solution and sodium silicate (NS) were used as alkali activators. NH concentration was set as a constant of 6 Molar. The mixture of fly ash (FA) and calcium carbide residue (CR) at a ratio of 75:25 by weight was used as a binder. EPS beads was used as a lightweight aggregate and the binder to EPS beads ratio was varied from 1:2.50 to 1:3.00 by volume. Workability in terms of flow was controlled between 200 and 300 mm. The compressive strength at 6 h up to 28 d and water absorption of lightweight alkali activated CLSM were determined. In addition, XRD and SEM of lightweight alkali activated CLSM were also investigated. The results revealed that the compressive strengths of lightweight alkali activated CLSM rapidly increased in the first 12 h, which were from 451 kPa to 731 kPa. The ratio of binder to EPS beads at 1:2.50 by volume was the optimum ratio and the ratio of NH:NS at 1:0.4 gave the highest compressive strength of lightweight alkali activated CLSM. Lightweight alkali activated CLSM obtained from this study had the compressive strength of 1,500–3,000 kPa and the density of 750–900 kg/m3 at 28 d, which can be used as structural backlinking.

Cost reduction approaches for fermentable sugar production from sugarcane bagasse and its impact on techno-economics and the environment

In an enzymatically driven lignocellulosic biorefinery, pretreatment and hydrolysis modules are the two most significant cost contributors for obtaining high gravity sugar solutions. The present study aimed to reduce the use of alkali and Cellic CTec2 during the bioprocessing of sugarcane bagasse (SCB). Later its impact on the overall process economics and the environment was evaluated. During pretreatment, solid loading of 15% (w/w) and use of 2% (w/v) sodium hydroxide at 121 °C for 30 min emerged as an optimum strategy. It resulted in > 65% delignification of SCB, retaining ≥ 90% and 65% of glucan and xylan fraction, respectively, in the pretreated biomass. Two approaches were evaluated in parallel to minimize the requirement of this commercial cellulase enzyme blend. The first strategy involved its partial replacement with an in-house enzyme cocktail by blending. The second route was performing hydrolysis with reduced loadings of cellulase enzyme blend above its optimum temperature, which gave more promising results. Hydrolysis of 20% alkali pretreated SCB with cellulase enzyme blend dosed at 15 mg protein g−1 glucan led to 84.13 ± 1 and 83.5 ± 2.3% glucan and xylan conversion yields respectively in 48 h at 52.5 °C. The filtrate and wash fraction contained ≥ 165 and ≥ 65 g L−1 sugar monomers representing glucose and xylose. However, in both the fractions > 75%, sugar accounted for glucose. The techno-economic analysis revealed that the sugar production cost from SCB was 1.32 US$/kg, with the optimized bioprocess. Environmental impact study showed that the process contributed to 1.57 kg CO2 eq in terms of climate change.