Alkaline Reagents Research Articles

Efficient fluoride recovery from poly(vinylidene fluoride), poly(vinylidene fluoride-co-hexafluoropropylene) copolymer and poly(ethylene-co-tetrafluoroethylene) copolymer using superheated water with alkaline reagent

Mineralization of poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) [poly(VDF-co-HFP)] copolymer, and poly(ethylene-co-tetrafluoroethylene) copolymer (ETFE) in superheated water in the presence of an alkaline reagent was investigated with the aim of developing a technique to recycle the fluorine element. These polymers underwent almost complete defluorination to form fluoride ions (F–) in the reaction solution at a relatively low temperature (250 °C) under Ar atmosphere. When PVDF was reacted with aqueous KOH (1.0 M) for 6 h, the amount of which corresponds to 10 times the molar amount of fluorine content (as atoms) in PVDF, the yield of F– released into the reaction solution reached 95 %. This transformation was accompanied by the formation of carbon rich reside, which consists of amorphous carbon. In contrast, for a treatment performed with O2 instead of Ar, significant differences were observed in the products: while F– ions efficiently produced in the reaction solution, carbon rich residue did not form and the major species that composed the total organic carbon content in the reaction solution was oxalate. Four consecutive runs (that is, after one reaction at 250 °C under Ar was complete, new PVDF was charged to the reaction mixture and then reacted again) caused no decrease of the F– yield. When treated with aqueous KOH (1.0 M) under Ar at 250 °C for 6 h, poly(VDF-co-HFP) and ETFE copolymers also completely mineralized to form F– ions with 100 and 98 % yields, respectively. Introducing Ca(OH)2 to the resulting reaction solutions of these (co)polymers after superheated water treatment produced pure CaF2, i.e., artificial fluorspar.

Investigation of green alkaline pH regulators on sapphire UV-CMP

This paper studied the feasibility of using green organic base to replace traditional inorganic base in sapphire UV-CMP. The effects of pH regulators on chemical and mechanical functions were researched by XPS, SEM, zeta potential and particle size analyses. The polishing effect of green organic base aminopropanol (AMP) is the best when the pH of the polishing solution is 11, compared with sodium metasilicate (SMSN) and KOH. Thus AMP can replace KOH in sapphire UV-CMP as a green alkaline pH regulator. However, with the increasing slurry pH values adjusted by the three alkaline reagents, the sample removal rate decreases significantly. And the reduction of organic base is greater. The main causes for the decreasing sapphire removal rate are the particle aggregation and the rising electric potential energy between abrasive particles, which leads to the increase of the distance between particles. This severely reduces the number of abrasives included in mechanical removal. The mechanical action is weakened, resulting in a serious decrease in the removal rate.

PHYTOCHEMICALS, MINERAL, ANTI-MICROBIAL ANALYSIS AND FTIR STUDY OF DIFFERENT EXTRACTS (ETHANOL, ETHYL ACETATE AND HEXANE) OF Ficus exasperate LEAF (SANDPAPER LEAF)

Ficus exasperate is a small tree well known on account of its very rough leaves being used as paper widely spread in all eco-regions of Nigeria. The plant has been ethno botanically reported to have diverse medicinal uses. It is used in herbal medicine to treat cough, hemorrhoid and lowering high blood pressure. Ethanol, ethyl acetate and hexane extracts of this plant were obtained by maceration and tested for antimicrobial activity using agar diffusion and micro broth method dilution techniques. However, Phytochemicals screening of the hexane extract revealed the presence of alkaloids, saponins, flavonoids, cardiac glycoside, steroid, legal test, alkaline reagent and phenol in Sandpaper with no traces of tannins and reducing sugar. The ethyl acetate extract revealed that all test was presence except from the Alkaline reagent and reducing sugar, while the ethanol extract revealed the presence of saponins, tannins, steroid, legal test, cardiac glycoside and phenols without traces of alkaloids, alkaline reagent and flavonoids. The Sandpaper exhibited a wide range of activity on Ethanol, N-haxane and Ethyl acetate extracts at concentration of 5.075, 1.665 and 3.09g respectively. The above results show that F. exasperata leaf contained bioactive substances with the highest inhibitory activities against some human pathogenic organisms. This study justifies the ethno pharmacological uses of these medicinal plants for treatment of microbial infections.

Physico-Chemical Properties of Pigment in Garden Pansy (Viola × Wittrockiana Gams.)

Pansy is a good potential resource for natural pigments due to its rich flower colours. In the present study, pigment from a pansy breeding line, E01, was extracted and its solubility in different reagents and stability under various environmental conditions were investigated. The pigment extracted displayed watersoluble property and was also dissolved in acid (HCl) and alkaline (NaOH) reagents and relatively polar solvents, but insoluble in nonpolar solvents. The pigment-water solution had an absorbance peak at 238 nm with amaranthine colour under acidic conditions. It was stable in aqueous solution under normal conditions. However, it was easily spoiled when exposed to high pH (> 4), high temperature (> 80℃) or under intense light exceeding 170000 lx. The stability of pigment was significantly influenced by Cu2+, but scarcely affected by Na+, Mg2+ and Ca2+. These results will be helpful for commercial prospects of pansy pigment in natural food colour industry. Bangladesh J. Bot. 51(3): 433-438, 2022 (September)

DEVELOPMENT OF COMPETITIVE DRILLING FLUIDS FOR HORIZONTAL DIRECTED DRILLING BASED ON BENTONITE OF CHERKASKY DEPOSIT

Taking into account the need for the post-war reconstruction of the country’s infrastructure, the development of high-quality drilling fluids based on Ukrainian mineral raw materials becomes a particularly urgent problem. Detailed studies of the rheological properties of aqueous dispersions of Na+-bentonite from the Cherkasky deposit (Ukraine) were carried out in relation to the development of drilling fluids for horizontal directional drilling. The effect of pH, ionic strength, concentration of the solid phase, alkaline reagent (Na2CO3) and polymer additives (PAC and PAA) on the rheological properties of Na+-bentonite dispersions was studied, and the most important correlations between the specified parameters and the performance characteristics of ready-made drilling fluids for horizontal directional drilling were obtained. A new, more effective PAA polymer is proposed to improve the viscosity-speed characteristics and other indicators of drilling fluids instead of the scarce imported PAC-polymer, and its optimal concentration is determined. It was established that with the introduction of small additives (0.005–0.025 %) of PAA polymer, drilling fluid based on Cherkasky Na+-bentonite in all its rheological characteristics is not inferior to imported analogues. The joint analysis of the obtained dependencies allowed to develop the optimal technology for obtaining bentonite gel and drilling fluids based on it, the indicators of which meet the requirements of the horizontal directional drilling. Based on the results of comparative studies of the rheological properties of drilling fluids in a wide range of deformation rates (0–1312 s–1), the competitiveness of the new drilling fluids has been proven on par with the best foreign analogues. Bibl. 17, Fig. 10, Tab. 4.

THERMODYNAMIC ANALYSIS OF THE CHEMICAL RESISTANCE OF CERAMIC MATERIALS IN THE RO- Al2O3-SiO2 SYSTEM

Operational characteristics, properties of modern aircraft and aerospace devices and their technical characteristics owe a lot to the radio engineering systems that are installed on them. Therefore, their protection and the selection of the necessary ceramic material, which will ensure the protection of electronic devices from interaction with the external environment, is an important task of modern materials science.
 In order to substantiate the choice of a crystalline phase as the basis of a radio-transparent ceramic material that will be used in aggressive environments, it is advisable to conduct thermodynamic calculations, namely changes in the Gibbs free energy of chemical reactions of the interaction of the crystalline phase with an aggressive environment. To carry out thermodynamic calculations of chemical stability reactions, the three-component system RO- Al2O3-SiO2 (RО – SrО, BaО) was chosen and the crystalline phases that can exist within them were determined. When choosing experimental crystalline phases, a complex of physico-chemical and operational requirements for radio-transparent materials was taken into account. From the point of view of thermodynamics, the corrosion behavior of the selected crystalline phases: celsian BaO·Al2O3·2SiO2, slavsonite SrO·Al2O3·SiO2, SrO·SiO2, and 2SrO·SiO2 is considered.
 The paper presents the results of thermodynamic calculations of changes in enthalpy, entropy, and Gibbs free energy of reactions to determine acid resistance (HСl, H2SO4, HNO3) and alkali resistance (NaОН, Na2CO3) of these compounds under standard conditions. It was established that all considered compounds have a thermodynamic probability of corrosion resistance to the action of alkaline reagents. In relation to an acidic environment, under normal conditions, celsian and slavsonite show acid resistance to hydrochloric acid, and they are least prone to interaction with sulfuric acid, but are able to actively interact with HNO3. Regarding the investigated binary compounds SrO·SiO2 and 2SrO·SiO2, all calculated reactions are thermodynamically favorable, i.e. interaction with acidic reagents occurs.
 The obtained results are analyzed and the correlation of the calculations of the reaction of celsian and hydrochloric acid with experimental data is given. It was concluded that it is rational to plan the production of ceramic products based on celsian and slavsonite or their heterophase mixture with a minimum content of binary oxides of strontium and barium.

Protonated amines mediated CO2 mineralization of coal fly ash and polymorph selection of CaCO3

The extensive consumption of acid and alkaline reagents is the most critical challenge hindering the development of the pH-swing process for CO2 mineralization. To deal with the problem, the present paper demonstrates the feasibility of using protonated amine as the reagent in coal fly ash (CFA) based leaching-mineralization process. The protonated amine could leach Ca2+ from CFA and be converted into free amine. The free amine was supposed to be in-situ regenerated into protonated amine by grab protons released from the CaCO3 precipitation reaction. 13 typical amines with varying amino types, pKa values, and side-chain length, were selected to systematically investigate the effects of amino groups on Ca2+ leaching performance from CFA, carbonation performance, CaCO3 nucleation, and crystal growth, as well as the process mechanism. Results indicated that effective Ca leaching, CaCO3 precipitation, and protonated amine regeneration were achieved. There was a linear relationship between the Ca utilization efficiency and pKa values of different amines. TEA obtained the highest CaCO3 yield and Ca utilization efficiency of 56.8 % and 16.8 %, respectively. In addition, amines provided excellent control of the size, polymorph, and morphology of the CaCO3 product. The primary amino group had a more pronounced effect on vaterite stabilization than secondary and tertiary ones. Introducing a side chain could promote the vaterite transforming to calcite and increasing chain length could decrease the vaterite particle size. Moreover, the maximal utilization efficiency in MEA was 15.9 % at conditions: 160 g/L solid to liquid ratio, 58 % degree of protonation, and 2.0 mol/L MEA concentration.

Hierarchically modified Mo/HZSM-5 via alkali treatment for improved activity in methane dehydroaromatization

Considering direct utilization of natural gas, methane dehydroaromatization (MDA) is a promising alternative to produce valuable aromatic hydrocarbons. However, the major limitation of the process is the low catalyst stability and durability due to simultaneous coking. This contribution depicts the modifications of HZSM-5 support via controlled desilication approach using two different kinds of alkaline reagents at two different concentrations. The physicochemical characterizations revealed that after the alkaline treatment, morphological features are modified e.g., pore size distribution, Si/Al ratio, and acidity of HZSM-5. In the catalytic activity results, it was observed that among all the alkali modified catalysts, 0.1 M NaOH modified Mo/HZSM-5 exhibited highest benzene formation rate (2 μmol/gcat.s) as compared to pristine Mo/HZSM-5 (0.4 μmol/gcat.s) in MDA reaction over 90 min of time on stream. The exceptional catalytic performance was attributed to the incorporation of secondary mesopores which in turn facilitated the effective diffusion of Mo species in the pore interiors and subsequently cause the formation of higher number of Mo-anchored active sites. Further, the coke tolerance ability was enhanced, which might be due to the entrapment of coke species in the generated mesopores, thus leaving higher amount of accessible active sites for aromatization.

In Vitro Antioxidant, Cytotoxic, Thrombolytic Activities and Phytochemical Evaluation of Methanol Extract of the Ampelocissus Barbata (Wall.) Leaves

Context: Oxidative stress and pertaining counterbalance mechanism are actively working in the living organisms. The overproduction of reactive oxygen species (ROS) in the ongoing equipoising process requires to be compensated by strong antioxidants. Plants as a rich source of antioxidants not only reduce oxidative stress but also possess cytotoxic, thrombolytic and phytochemical potentials. Aims: To find out the antioxidant, cytotoxic, thrombolytic and phytochemical capabilities of the methanolic extracts of Ampelocissus barbata (Wall.) leaves. Methods and Material: Assessment of the in vitro antioxidant activity of extract was carried out using DPPH radical scavenging assay, determination of reducing power capacity and total phenolic content. The thrombolytic activity was assessed by disintegration of clot and prospective phytochemical activities were by standard qualitative analysis such as Mayer’s, Dragendroff’s Wagner’s and Hager’s Reagent test for alkaloids; Libermann-Burchared and Salkowski Reagent tests for steroid and terpenoids; Molish Reagent, Benedict’s Reagent, Fehling’s Solution A & B reagent test for carbohydrates; Ferric Chloride (5%) Solution, Potassium Dichromate (10%) Solution tests for tannins; Shinoda test and Alkaline reagent test for Flavonoids; Froth tests & Haemolysis test for Saponins. Statistical analysis used: The statistical analysis was carried out using GraphPad Prism and Microsoft excel Results: Appreciable DPPH radical scavenging activity of the extract was observed with the IC50 value of 107.47±1.46 µg/ml. A significant correlation was found between the standard ascorbic acid (AA) and the plant extracts at the p˂0.05 for the reducing power assay where, the activity increased with the concentration of the extracts and the highest absorbance value was 3.025±0.15 and 1.826±0.006 for the AA and the extracts respectively. The plant also accommodates a considerable amount of polyphenols, reflected in the value of gallic acid equivalent 277.397±0.419 mg/ml. Finally, the percentage (%) of clot lysis for the thrombolytic activity was revealed to be 7.031±0.697, 35.297±1.307, and 75.083±0.599 for the water (negative control), extract, and the standard Streptokinase respectively. The study revealed the presence of phytochemicals namely alkaloids, flavonoids, tannins and glycosides. Conclusions: The study disclosed the promising in vitro activity of the plant, which necessitates the further analysis for the isolation and evaluation of the active principles.

Cleaning of soapstocks of oil and fat industry enterprises by physico-chemical methods

Industrial wastewater from the oil and fat industry contains a variety of pollutants that pass into wastewater during processing of soapstocks: fats and fatty acids and their salts (aqueous soap solutions), glycerin, phosphoglycerides, neutral fat, phosphatides, proteins, carbohydrates dyes (carotene, carotenoids, chlorophyll, etc.), unsaponifiable and waxy substances, salts - sodium sulfate and chloride, mechanical impurities, etc. Soapstocks have a complex and volatile composition, which depends on the nature and properties of its components, the amount of fat-related substances in it. The effect on alkaline reagents and coagulant reagents on co-stocks is proposed and investigated. The obtained results allow to establish rational doses of reagents for effective removal of pollutants from soapstocks. In the studied wastewater, the concentration of organic matter according to the HSC was 40,000 mg / dm3, low pH 2, at which the stability of the state of organic pollutants in the water (no foaming, sedimentation). Calcium carbonate and sodium hydroxide solutions were used as alkalizing reagents. Comparison of the effects obtained under the action of calcium carbonate, compared with the effects obtained with sodium hydroxide, showed 2.4-2.5 times greater efficiency for HSC. The effects of removal of suspended solids and organic substances by HSC at a dose of aluminum sulfate 2 g / dm3 were, respectively, 85.6% and 72% when providing a pH of 5.5 by the action of calcium carbonate. However, it is not possible to remove organic matter to acceptable values ​​when discharged into the city sewer in one stage of purification. Therefore, both after alkalization with calcium carbonate and after coagulation with aluminum sulfate, it is proposed to use the flotation method of phase separation, for example, using air supply through porous materials.

Modification of Orange Bagasse with Reactive Extrusion to Obtain Cellulose-Based Materials

Orange bagasse (OB) could be considered a sustainable, renewable, and low-cost biomass for the extraction of cellulose. In this context, reactive extrusion can be considered an excellent, eco-friendly, alternative process for the extraction of cellulose from lignocellulosic materials. Thus, the present study aimed to obtain cellulose-based materials with a reactive extrusion process and also to investigate the impact of pectin on the delignification process. Two groups of samples (OB and depectinizated OB) were submitted to extrusion with sulfuric acid or sodium hydroxide in one-step processes. The cellulose content of extruded materials was highly affected by pectin content in the raw material; the thermal profile (TGA curves) and crystallinity also changed. The cellulose content of modified materials ranged from 18.8% to 58.4%, with a process yield of 30.6% to 79.2%. The alkaline reagent provided the highest cellulose content among all extrusion treatments tested, mainly for OB without pectin. The extrusion process was considered an efficient and promising process for extracting cellulose from citrus residue. Materials produced in this study can be used as sources of cellulose fiber for various products and processes, such as in the food industry, fermentation substrates, or refined applications after subsequent treatments.

Assessment of Potential Benefits of Functional Food Characteristics of Beetroot Energy Drink and Flavored Milk.

Objective This study was designed to determine the antioxidant activity of the extracts of beetroot by using beetroot energy drink and flavored milk (products). Material & Methods. This experimental trial was conducted at Jinnah University for Women, Pakistan, under the approval of local institutional review board number JUW/DFST/RCB010/2020. All the materials such as beetroot, carrot, cucumber, and lemon were obtained commercially from which two products were formulated: beetroot energy drink (sample1) and flavored milk (sample 2). These formulated products were evaluated for quality analysis (pH and brix), phytochemical screening using the Keller-Kiliani test, Salkowski's test, Alkaline reagent test, lead acetate test, ferric chloride test, protein test, quantitative test of phenol, antioxidant activity, sensory analysis, and shelf life study. The paired t-test was applied to detect significant differences between two samples. Results The phytochemical analysis revealed that cardiac glycosides, phytosterol, flavonoids, and terpenoids were found in both energy booster drink (EBD) and flavored milk (FM) except phenolic compounds that were found only in EBD. The antioxidant capacity of beetroot juice was far greater than FM. The statistical sensorial analysis of FM and EBD reported a significant mean difference between most of the groups with p < 0.0001. Conclusion This study concludes that energy drinks having beetroot indicated higher antioxidant capacity than flavored milk. The nutraceutical products (energy booster drink and flavored milk) containing beetroot are enriched with optimum quantities of proteins and fats and low carbohydrates at a stable pH with an adequate total energy content.

Technology for obtaining high-pure magnesium compounds using the hydrolytic processes of sedimentation

In nature, magnesium compounds are distributed in the form of such minerals as dolomite, magnesite, serpentinite, brucite, and in the form of such solutions as sea and ocean waters, salt lakes, bischofite. The main popular magnesium compounds are its chloride, hydroxide, and oxide. The most common technology for obtaining magnesium hydroxide is based on the action of alkaline reagents on solutions of magnesium. However, the technology has significant drawbacks. The main issue is that magnesium hydroxide cannot be obtained free of impurity metal ions, and the sediment itself has an extremely low filtration rate from the solution in which it is formed. Magnesium hydroxide is an excellent sorbent collector for the ions of most metals, so it is possible to utilize this property of absorption of magnesium hydroxide to produce other highly pure compounds, for medicine and pharmacopeia. This paper investigates the processes of alkaline hydrolysis of magnesium chloride and the formation of magnesium hydroxide sediment, the kinetics of processes, as well as the properties of sediments. Empirical formulas for sediment production parameters with a high filtration coefficient that exceeds the known values of 1·106have been derived. The study reported here hasrevealed the possibility of obtaining in a relatively simple way highly pure chloride, hydroxide, and magnesium oxide, sodium chlorides, potassium, calcium, in which the impurity 3d metals content does not exceed the value as a percentage of (1‒4)·10-7. Due to the properties of highly pure magnesium compounds to the sorption of metal ions, it is possible to create reference samples of chemical elements for the needs of metrology. For example, to create MR phantoms to verify measurements and check the operation of magnetic resonance imaging (MRI) in medical institutions. Especially pure magnesium hydroxide can be used for instrumental methods of analytical chemistry (X-ray fluorescent, neutron-activation methods) when fabricating chemical references for testing laboratories.

Potential of Sodium Hydroxide Pre treatment of Prosopis juliflora for Fermentable Sugar Production

The present study aimed at investigating the potential of sodium hydroxide (NaOH) as a viable alkaline reagent for lignocellulosic pre treatment considering its various benefits of pre treatment. Prosopis juliflora was pre treated with different NaOH concentrations of 1–3 % for varying treatment times of 15-60 min at temperatures of 100, 120 and 140 °C in an autoclave. Maximum lignin reductions at different temperatures were all obtained at the combinations of highest NaOH concentrations and longest treatment times, which indicated a close relationship between pre treatment severity and lignin reduction. The highest carbohydrate retention of 65.09 per cent was observed in the sample pre treated at 120 °C with 2% NaOH and 60 min. Three pre treatment conditions were selected for subsequent enzymatic hydrolysis with Cellic CTec2® enzyme complex for fermentable sugar production along with untreated biomass as control to study the soaking effect. The biomass pretreated with 2.0 % NaOH for 1 h at 120 °C and loaded with 30% enzyme was determined to be the most effective as it resulted in generation of 583.9 mg sugar/g biomass for a corresponding carbohydrate conversion of 90.86 %.

Environmental management and potential valorization of wastes generated in passive treatments of fertilizer industry effluents

A phosphogypsum stack located in SW Spain releases highly acidic and contaminated leachates to the surrounding estuarine environment. Column experiments, based on a mixture of an alkaline reagent (i.e., MgO or Ca(OH)2) dispersed in an inert matrix (dispersed alkaline substrate (DAS) technology), have shown high effectiveness for the treatment of phosphogypsum leachates. MgO-DAS and Ca(OH)2-DAS treatment systems achieved near total removal of PO4, F, Fe, Zn, Al, Cr, Cd, U, and As, with initial reactive mass:volume of leachate treated ratios of 3.98 g/L and 6.35 g/L, respectively. The precipitation of phosphate (i.e., brushite, cattiite, fluorapatite, struvite and Mn3Zn(PO4)2·2H2O) and sulfate (i.e., despujolsite and gypsum) minerals could control the solubility of contaminants during the treatments. Therefore, the hazardousness of these wastes must be accurately assessed in order to be properly managed, avoiding potential environmental impacts. For this purpose, two standardized leaching tests (EN-12457-2 from the European Union and TCLP from the United States) were performed. According to European Union (EN-12457-2) regulation, some wastes recovered from DAS treatments should be classified as hazardous wastes because of the high concentrations of SO4 or Sb that are leached. However, according to United States (US EPA-TCLP) legislation, all DAS wastes are designated as non-hazardous wastes. Moreover, the solids generated in the DAS systems could constitute a promising secondary source of calcite and/or P. This research could contribute to worldwide suitable waste management for the fertilizer industry.

Chemical resistance of celsian ceramics in acid and alkaline reagents

In the article, the chemical stability of celsian ceramics at different firing temperatures was investigated and the structural-phase features of the obtained samples before and after interaction with alkaline and acid media were studied.&#x0D; The technology of obtaining test samples was two-stage. The first stage was the synthesis of the celsian phase in a muffle furnace at a temperature of 1200 °C with a holding time of 2 hours and subsequent cooling together with the furnace. The second stage took place in a silitic furnace at temperatures of 1300, 1350 and 1400 °C with a set rate of 15 deg/min and holding at a maximum temperature of 4 hours. The chemical resistance of celsian ceramics was determined in relation to 20 % solutions of HCl and NaOH. The phase composition of the test samples was determined using the method of X-ray phase analysis (X-ray diffraction) using a DRON-3M diffractometer. The studies of the experimental samples microstructure and the surface morphology of their faults were carried out by the direct method of scanning electron microscopy using a scanning electron microscope PhenomPro.&#x0D; It was found that in relation to the 20 % solution of NaOH celsian ceramics was insoluble and has a value of alkali resistance in the range of 99.47—99.67 %. The study of microstructure and phase composition of celsian ceramics samples after treatment with 20 % NaOH solution showed that in all studied samples there was only a crystalline phase of celsian, the corrosion process didn’t occur. In relation to the 20 % HCl solution, the process of celsian ceramics corrosion was observed with the complete chemical interaction of the celsian phase with hydrochloric acid and the subsequent formation of the barium chloride dihydrate phase.

Effect of Curing Temperature on the Mechanical Strength of Alkali Activated Laterite Geopolymeric Samples

A huge amount of carbon dioxide is released in the Portland cement production process. A large quantity of greenhouse gases is produced because of the significant amount of energy consumption via making bricks through firing. Using the pozzolanic sources containing the aluminosilicate and alkaline reagents, a new type of green materials called geopolymeric materials are produced with quite lower environmental hazards. The use of laterite as an iron-rich aluminosilicate material has a high potential for building materials. In this study, the effect of the curing temperature and characteristics of the alkaline reagent including the concentration of sodium hydroxide solution and the water-glass to sodium hydroxide mass mixing ratio on the mechanical strength of the laterite-based, oven-cured geopolymer samples was investigated. The results showed that the curing temperature had a significant effect on the compressive strength of the laterite-based geopolymer samples so that with a 15°C change at the curing temperature, the compressive strength of the samples could be multiplied and a sharp increase in the mechanical strength could occur. Also, according to the results of this study, the 6 M sodium hydroxide is recommended for the construction of the laterite-based geopolymer materials with low cost and relatively high strength, and for the construction of higher-strength building materials, the 14 M sodium hydroxide is recommended.

THE EFFECT OF SLAG FROM THE PRODUCTION OF METALLIC CHROMIUM ON THE TECHNICAL CHARACTERISTICS OF ACID-RESISTANT TILES

Object of research: acid-resistant tiles obtained on the basis of unenriched kaolin and waste of non-ferrous metallurgy - slag from the production of metallic chromium, non-ferrous metallurgy wastes occupy the second place after chemical production waste in terms of the amount of especially harmful various pollutants. Various environmental pollutants, such as dust and slag, containing very harmful substances (especially hexavalent chromium, antimony, arsenic, lead and mercury) have a very negative impact on the health of people living within a radius of 50 km from metallurgical plants. The use of large-tonnage waste of non-ferrous metallurgy - aluminum-containing slag from the production of metallic chromium in an amount of 40 % allows to obtain acid-resistant tiles with high physical, mechanical and chemical parameters at a firing temperature of 1300 °C and reduce environmental stress in the area of non-ferrous metallurgy production. Studies have shown that it is impossible to obtain acid-resistant tiles from non-enriched kaolin clay containing less than 18 % A12O3 even at a firing temperature of 1300 °C. The introduction of an optimal amount of chamotte (40 %) into the ceramic mass allows to obtain acid-resistant tiles that meet the requirements of GOST for physical and mechanical parameters at a firing temperature of 1300 °C. The use of aluminum-containing slag from the production of metallic chromium in ceramic compositions in an amount of 40 % (as well as chamotte) allows to obtain products with high physical, mechanical and chemical parameters at a firing temperature of 1250 °C. The introduction of alumina-containing aluminum-containing slag from the production of metallic chromium into the compositions of ceramic masses contributes to the formation of corundum. Corundum is characterized by high chemical resistance to acidic and alkaline reagents. At this temperature, even HF practically does not affect it.

Effect of nanotegnogenic high-alumina raw materials on the physical and mechanical parameters and phase composition of acid-resistant materials

The use of nanotechnogenic high-alumina (Al2O3 &gt; 70 %) raw materials of petrochemical production ― the spent IM2201 catalyst in the production of acid-resistant materials based on unenriched kaolin clay makes it possible to obtain products with high physical, mechanical and chemical parameters in the range of firing temperatures of 1250‒1300 o C. Nanotechnogenic raw materials contribute to an increase in surface energy, which is the source of the sintering process. Studies have shown that in compositions based on unenriched kaolin clay and chamotte from it, which do not contain nanotechnogenic high-alumina raw materials, mainly mullite is formed, which mainly forms the operational properties of ceramic products. X-ray diffractometric analysis showed that the introduction of nanotechnogenic high-alumina raw materials into the compositions of ceramic masses contributes to the formation of corundum. IR spectroscopic analysis confirmed the data of X-ray studies. Corundum is characterized by high chemical resistance to acidic and alkaline reagents and gives acid-resistant materials high physical and mechanical properties. Ill. 4. Ref. 33. Tab. 5.

Extraction, purification of tyrosinase and tyrosinase inhibitory activity of four medicinal plants from Nanded district (MS), India

The systematic study aims to explore the tyrosinase inhibitory activity of selected plants. The study included extraction, purification, and inhibition of the enzyme. Tyrosinase has an important role in melanin formation, is responsible for the production of colour pigments of skin, hair, and eye. In the presents study, tyrosinase was isolated from Mushrooms, isolation of enzyme was done by acetone precipitation procedure and precipitation of enzyme was done with ammonium sulphate precipitation method. Plants selected for extraction were Azadirachta indica (Neem), Manikara zapota (Chiku), Annona squamosa (Sitaphal), and Hibiscus Rosa-sinesis (China rose). For phytochemical screening Alkaloids-Mayer’s Test, Flavonoids (Shinoda Test, Alkaline Reagent Test), sugar (Benedict’s reagent Test), Glycosides (Borntrager's Test), Phenolic compounds Test (Ferric chloride Test, Gelatin Test, Lead Acetate Test). Mushroom tyrosinase inhibitory assay was determined by the spectroscopic method. The enzyme precipitates on 85% saturation of ammonium sulphate, dialyzed and loaded on preequilibrated DEAE cellulose column for further purification at 1ml/min flow rate. Purification shows the 26 frac-tions giving very good enzyme activity. The specific activity of the enzyme after all purification steps was found to be 2 U/µg proteins with 17.09- fold purify-cation.