Concentrated Mineral Acids Research Articles

Experimental Investigation of the Influence of Composition Changes in Shale on Pore Structure and Fractal Characteristics under Different HCl Concentrations.

Acidification is a promising stimulation technique for improving the pore structure of low-permeability shale reservoirs and enhancing shale gas production. Variations in the mineral composition and acid concentration play a significant role in altering the pore systems in shale reservoirs, thereby affecting shale gas transport and production. To investigate the effect of shale composition on pore structure and fractal characteristics under hydrochloric acid (HCl) treatment, experiments were carried out on carbonate-rich (68%), carbonate-medium (45%), and carbonate-poor (2%) shales with different concentrations of HCl solution (1, 5, 10 wt %). X-ray diffraction (XRD), low-temperature nitrogen adsorption, and fractal theory were performed to investigate variations in mineral composition, pore structure, and fractal characteristics of the unreacted and reacted shales. The results illustrated that the HCl treatment significantly reduced the content of carbonate minerals, and the dissolution degree of carbonate minerals increased with the increase in HCl concentration. More meso- and macropores were generated for carbonate-rich and carbonate-medium shale, while more micro- and mesopores were generated in carbonate-poor shale, which led to the increase in total pore volume (TPV) and total specific surface area (TSSA) at different degrees. Moreover, the pore surface roughness (D 1) and structure complexity (D 2) were reduced with the increase of HCl concentration for carbonate-rich shale, while the alteration of D 1 and D 2 showed an opposite trend for carbonate-poor shale. Additionally, D 1 decreased and D 2 increased for carbonate-medium shale. Relevant results could provide theoretical references for the acid fracturing of shale reservoirs with varying mineral compositions.

N-Morpholine-N'-benzoylthiourea as an extractant for Pb(II) and Cu(II) in aqueous media: Crystal structure of bis(N-morpholine-N′-4-benzoylthioureato)lead(II)

The reaction of N-morpholine-N′-benzoylthiourea (L: HBMOR) and lead(II) acetate gave a neutral, stable metal(II) complex of type ML2. The Pb(II) complex crystallized in a monoclinic crystal system with P21/n space group. The complex was further characterized by spectroscopic and microanalytic analyses. The solvent extraction behaviors of Pb(II) and Cu(II) ions were investigated in aqueous media containing HBMOR/CHCl3 as extracting reagents. The solvent extraction of Pb(II) and Cu(II) ions from solutions of varying pH, varying concentrations of mineral acids (HCl, HNO3 and H2SO4), varying concentrations of masking agents (EDTA, KCN and KH[C8H6O4]) and varying concentrations of salting-out agents (NaCl, Na2SO4, KNO3) in chloroform solutions of HBMOR were studied. Pb(II) and Cu(II) ions were quantitatively extracted at pH = 7 in 10 min (HCl = 0.01 M) and pH = 8 in 5 min (H2SO4 = 0.01 M), respectively. The Pb(II) ions were quantitatively extracted with minimal interference from EDTA (0.01 M), KCN (0.50 M), and potassium hydrogen phthalate (1.0 M), while the Cu (II) ions were extracted with EDTA (1.0 M), KCN (1.0 M) and potassium hydrogen phthalate (0.01 M). The order of increasing interference for the extraction of Pb(II) and Cu(II) ions was KCN > potassium hydrogen phthalate > EDTA. Sodium sulfate (0.01 M) in HCl enhanced the extraction of Pb(II) ions, while sodium chloride (0.50 M) in HCl enhanced the extraction of Cu(II) ions. pH0.5 values of 0.67 and 2.70 were obtained for Pb(II) and Cu(II) ions, respectively, indicating that the separation of the two metal ions is favorable with HBMOR.

Unlocking the Potential of Chemically Modified Carbon Gels in Gallic Acid Adsorption.

This study deals with the preparation of adsorbents from a commercial xerogel by chemically modifying its surface with concentrated mineral acids and alkali metal chlorides, their physicochemical characterization, and their use as adsorbents for gallic acid in aqueous solution. Although there are publications on the use of carbon xerogels as adsorbents, we propose and study simple modifications that can change their chemical properties and, therefore, their performance as adsorbents. The adsorbate of choice is gallic acid and, to our knowledge, there is no history of its adsorption with carbon xerogels. The prepared adsorbents have a high specific surface area (347-563 m2 g-1), better pore development for samples treated with alkali metal chlorides than with mineral acids, and are more acidic than the initial xerogel (p.z.c range 2.49-6.87 vs. 7.20). The adsorption equilibrium is reached in <16 h with a kinetic constant between 0.018 and 0.035 h-1 for the pseudo-second-order model. The adsorption capacity, according to the Langmuir model, reaches 62.89 to 83.33 mg g-1. The adsorption properties of the commercial xerogel improved over a wide range of pH values and temperatures. The experimental results indicate that the adsorption process is thermodynamically favored.

Platinum recycling from fuel cell-spent electrocatalysts using oxidative leaching in HCl solution

The recovery of platinum (Pt) from electrocatalysts in spent proton exchange membrane fuel cells is promising and important for the sustainable development of such a noble metal. Conventional leaching of Pt in the aqueous phase typically requires the use of high concentration of mineral acids and the presence of strong oxidants owing to its thermodynamic stability and non-reactive properties. In the present study, the dissolution of Pt from a Pt/C fuel cell electrocatalyst was investigated using a simple and efficient process under moderate conditions in chloride media. Notably, the leachability of Pt was high ∼76% in a solution of low concentration HCl 2.0 M at 90 °C for 120 min in the absence of an oxidant. The enhancement of Pt leaching efficiency can be obtained using various oxidizing agents HNO3, H2O2, NaClO and NaClO3, and NaClO3 shown the most effective improvement from 76% to 88%. The dissolution of Pt in a solution of 2.0 M HCl and 3.0 wt% NaClO3 improved to 98% by the increase in leaching temperature from 50 to 90 °C. Kinetic studies indicated that Pt leaching in HCl in the presence of NaClO3 followed a chemical-controlled mechanism with an activation energy (Ea) of 40.6 kJ/mol. Based on the findings of this study, an efficient process is proposed to recover and reuse Pt from an electrocatalyst sample of spent fuel cells, including oxidative leaching, chemical precipitation and laser reduction.

The importance of the pretreatment of samples in Nd quantification from NdFeB magnets through inductively coupled plasma atomic emission spectroscopy (ICP-OES)—a rapid and streamlined methodology

In this study, we emphasize the critical role of sample pretreatment. We report on the behavior of NdFeB magnet samples exposed to four different acid media for digestion. NdFeB magnets are becoming a significant source of neodymium, a rare-earth element critical to many technologies and a potential substitute for traditional mining of the element. To address this, we meticulously tested nitric acid, hydrochloric acid, acetic acid, and citric acid, all at a concentration of 1.6 M, as economical and environmentally friendly alternatives to the concentrated mineral acids commonly used in the leaching of these materials. The pivotal stage involves the initial characterization of samples in the solid state using SEM-EDX and XPS analysis to obtain their initial composition. Subsequently, the samples are dissolved in the four aforementioned acids. Finally, neodymium is quantified using ICP-OES. Throughout our investigation, we evaluated some analytical parameters to determine the best candidate for performing the digestion, including time, limits of detection and quantification, accuracy, recovery of spike samples, and robustness. After careful consideration, we unequivocally conclude that 1.6 M nitric acid stands out as the optimal choice for dissolving NdFeB magnet samples, with the pretreatment of the samples being the critical aspect of this report.

Nanosilica from Averrhoa bilimbi juice pre-treated rice husk: Preparation and characterization

The preparation of nanosilica from rice husk without using any concentrated mineral acids is a novel concept. This work proposes a bioleaching strategy to remove metallic impurities from rice husk for the preparation of nanosilica. Herein, nanosilica (BJRHS) was prepared by calcinating Averrhoa bilimbi juice pre-treated rice husks in a muffle furnace. The chemical and atomic structures of commercial precipitated silica (CS), rice husk ash (RHA), and BJRHS were analyzed using different analytical techniques. The optimal leaching time, calcination temperature, and calcination time were 1 h, 500 °C, and 6 h respectively. The particle size of BJRHS was found to be 6–12 nm, which is less than that of RHA and CS. The BET surface area of BJRHS (204 m2/g) was found to be greater than RHA (110.5 m2/g) and CS (172.1 m2/g). Mesoporous nanosilica with excellent surface area and purity was produced sustainably from rice husk which could be recommended to use in the field of catalysis, polymer technology, etc.

Comparison of different technologies using organic acid and mineral acid solvents on pectin extraction from apple pomace

Pectin is one of the most widely used functional polysaccharide, which is extensively used in food, biotechnological, chemical, cosmetic, and pharmaceutical industries. Pectin can be suitably extracted from apple pomace which is the main by-product of apple juice industry. In this study, pectin obtained from microwave assisted extraction (MAE) and conventional extraction (CE) were compared in terms of extraction yield, extraction time and extraction temperature. The type of acids namely organic acids and mineral acids were also compared, in which pectin from apple pomace was extracted using different concentration of organic acid (citric acid, 0.1 M and 0.05 M) and mineral acid (hydrochloric acid, 0.1 M and 0.05 M). The best extraction condition of the extraction process was found to be higher in yield by using citric acid at microwave power of 180 W, solid-to-liquid ratio of (1:25), concentration of citric acid of 0.1 M for 90 s. Under these conditions, the extraction yield of pectin reached 19.1 ± 0.2%, methoxyl content (5.27%), anhydroglacturonic acid (43.38%) and degree of esterification (68.97%). The current work showed that critic acid is a ‘green’ and safe acidic solvent that could be used to extract pectin from apple pomace that was highly competitive and environmentally friendly process. The microwave Assisted extraction method is considered to be a potential alternative conventional (traditional) extraction method. The obtained data undertakes that apple pomace obtained by the green extraction has a great potential to be a valuable source of pectin, while preserving similar quality to conventional sources of pectin.

Effect of heat treatments and aggressive media on mechanical properties of porous polytetrafluoroethylene membranes fabricated via electrospinning

Electrospinning is a modern alternative to the expanded method for producing porous polytetrafluoroethylene membranes. High strength and relative elongation, as well as the ability to maintain these properties for a long time when exposed to aggressive media at high temperatures, determine the application scope of the electrospun polytetrafluoroethylene membranes. Herein, we report the effect of Polytetrafluoroethylene/Polyvinyl alcohol ratio in the electrospinning solution, heat treatment mode (quenching and annealing) and aggressive media at high temperatures on the shrinkage, tensile strength and relative elongation of electrospun polytetrafluoroethylene membranes. We found that decreased Polytetrafluoroethylene/Polyvinyl alcohol ratio in the electrospinning solution increases shrinkage, but improves tensile strength and relative elongation of polytetrafluoroethylene membranes. Quenching of membranes after heating is a more preferable treatment option than annealing as it allows to obtain the membrane with less shrinkage and better mechanical properties. Exposure of electrospun polytetrafluoroethylene membranes to concentrated mineral acids and alkalis, a bipolar aprotic solvent, engine oil and deionized water at 100 °C for 48 h did not deteriorate their tensile strength and relative elongation.

Heterocyclizations based on N-(R-hydrazine-1-carbonothioyl)cycloalkancarboxamides: functionalized azoles and their antimicrobial activity

Synthesis and structural modification of azoles remains an important area of medical chemistry and allows to obtain new compounds with a wide range of biological activity. Among the significant number of azoles, 1,3,4-thiadiazoles and 1,2,4-triazoles attract special attention, among which are known drugs, larvicides, insecticides, growth regulators, etc. Even though heterocyclizations of functionally substituted hydrazines for their synthesis are well studied, N-(R-hydrazine-1-carbonothioyl)cycloalkanecarboxamides, and nowadays, remain reagents with undiscovered potential. Moreover, the introduction of lipophilic “pharmacophore” fragments (cycloalkanes) in the structure of 1,3,4-thiadiazoles and 1,2,4-triazoles is a promising direction for their modification. That should provide additional intermolecular interactions with enzymes and may lead to enhancement or alteration of the biological activity vector. Thus, the synthesis of new derivatives of this class of compounds and the study of their antibacterial properties remains an urgent problem of medical and organic chemistry. Aim. To investigate the heterocyclization of N-(R-hydrazine-1-carbonothioyl)cycloalkanecarboxa-mides, to establish the structure and antibacterial activity of the synthesized compounds. Materials and methods. Methods of organic synthesis, physical and physical-chemical methods of analysis of organic compounds (NMR 1H-spectroscopy, chromato-mass spectrometry, elemental analysis). The antimicrobial activity of the synthesized compounds was studied according to the generally accepted method for standard strains of microorganisms and fungi. Results. The peculiarities of heterocyclization of N-(R-hydrazine-1-carbonothioyl)cycloalkanecarboxamides have been studied and the factors influencing this reaction have been elucidated. It was shown that these compounds under the conditions of the heterocyclization reaction in concentrated mineral acids form 5-R-2-amino-1,3,4-thiadiazoles. The intermediate undergoes additional hydrolysis by cleavage of the cycloalkanecarboxyl fragment. Alternative methods for the synthesis of 5-R-2-amino-1,3,4-thiadiazoles were proposed. For the first time, the original 4-cycloalkanecarbonyl-3-(amino-,phenyloxo-(thio)methyl-1,5-dihydro-4H-1,2,4-triazole-5-thiones were synthesized by prolonged heating of the corresponding disubstituted thiosemicarbazides. It was not possible to extend this reaction to other diacylthiosemicarbazides, the latter undergo heterocyclization in the presence of sodium hydroxide with the formation of the known 5-R-2,4-dihydro-3H-1,2,4-triazole-3-thiones. 1H NMR spectra were studied, analyzed, and regularities of splitting of characteristic protons in functionalized azoles were established. Conducted microbiological screening was showed that 5-R-2-amino-1,3,4-thiadiazoles, 4-cycloalkanecarbonyl-3-(amino-,phenyloxo-(thio)methyl-1,5-dihydro-4H-1,2,4-triazole-5-thiones and 5-R-2,4-dihydro-3H-1,2,4-triazole-3-thione were less effective antibacterial and antifungal agents (MIC 100–200 μg/ml) compared with N-(R-hydrazine-1-carbonothioyl)cycloalkanecarboxamides (MIC 3.125–200 μg/ml). Conclusions. It was found that N-(R-hydrazine-1-carbonotioyl)cycloalkane-carboxamides, depending on the conditions of heterocyclization form 5-R-2-amino-1,3,4-thiadiazoles, 3-(phenyloxo-(thio)methyl-1,5-dihydro-4H-1,2,4-triazole-5-thiones or 5-R-2,4-dihydro-3H-1,2,4-triazole-3-thiones. It was established that synthesized azoles were shown less effective antimicrobial and antifungal activity in comparison with N-(R-hydrazine-1-carbonothioyl)cycloalkanecarboxamides.

Development and Validation of a Method for the Analysis of Zinc Oxide in Cosmetic Matrices by Flame Atomic Absorption Spectroscopy

A fast and simple method for the extraction and Flame Atomic Absorption Spectroscopy (FAAS) quantification of ZnO in different cosmetic matrices, including lipsticks, water-in-oil foundations, and oil-in-water creams, was developed and validated, according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) and the United States Pharmacopeial Convention guidelines. The sample preparation consisted of an ultrasound-assisted ethanolic extraction of ZnO followed by digestion with 1 M nitric acid (HNO3). Samples were analyzed by Flame Atomic Absorption Spectroscopy (FAAS). Specificity, linearity, the limit of detection (LOD), the limit of quantification (LOQ), sensitivity, precision, and accuracy parameters were studied. The robustness of the method was evaluated with a five-variable Youden–Steiner model. The method was specific for ZnO, and the extraction procedure did not affect the stability of the signal compared to the background. The method was linear in the range 0.2–1.0 mg/L with LOD/LOQ values equal to 0.0156 (mg·L−1)/0.0473 (mg·L−1), 0.0098 (mg·L−1)/0.0297 (mg·L−1), 0.0113 (mg·L−1)/0.0341 (mg·L−1), and 0.0131 (mg·L−1)/0.0397 (mg·L−1), respectively, for raw material, lipstick, liquid foundation, and emulsion matrices. Regarding precision, the %RSD values were below 3.0% for repeatability and intermediate precision. Global reproducibility RSD was below 8.0% for all matrices. The percentage of recovery was not statistically different from 100% in all cases. The final concentration was found to be a critical variable for all matrices except for the raw material. The variables associated with the extraction step (ethanol volume, bath temperature, and extraction time) were critical in the extraction of liquid foundations and cream emulsions. The method reduces the number and concentration of mineral acids spent on the digestion of ZnO, and its application is extendable to raw materials. This development is an adequate tool for routine analysis and cosmetic quality control of chemically different products that contain ZnO as ultraviolet radiation (UV) filter, to guarantee regulatory compliance and ensure the safety and efficacy of products delivered to consumers.

Decontamination of spent ion exchange resins contaminated with iron-oxide deposits using mineral acid solutions

The efficiency of decontamination of model spent ion exchange resins, contaminated with magnetite and hematite, with mineral acid solutions, and using electro-decontamination, was evaluated. It has been shown that effective hematite dissolution occurs in concentrated mineral acid solutions. However, the use of direct current increases the decontamination efficiency of spent ion exchange resins contaminated with hematite. It is determined that with increasing voltage and acid concentration, the dissolution efficiency of hematite deposits increases and can exceed 99%. It has been shown that hematite dissolution is accompanied by secondary adsorption of radionuclides due to ion exchange, which can be removed with sodium nitrate solutions.

Synthetic, Mechanistic, and Biological Interrogation of Ginkgo biloba Chemical Space En Route to (-)-Bilobalide.

Here we interrogate the structurally dense (1.64 mcbits/Å3) GABAA receptor antagonist bilobalide, intermediates en route to its synthesis, and related mechanistic questions. 13C isotope labeling identifies an unexpected bromine migration en route to an α-selective, catalytic asymmetric Reformatsky reaction, ruling out an asymmetric allylation pathway. Experiment and computation converge on the driving forces behind two surprising observations. First, an oxetane acetal persists in concentrated mineral acid (1.5 M DCl in THF-d8/D2O); its longevity is correlated to destabilizing steric clash between substituents upon ring-opening. Second, a regioselective oxidation of des-hydroxybilobalide is found to rely on lactone acidification through lone-pair delocalization, which leads to extremely rapid intermolecular enolate equilibration. We also establish equivalent effects of (-)-bilobalide and the nonconvulsive sesquiterpene (-)-jiadifenolide on action potential-independent inhibitory currents at GABAergic synapses, using (+)-bilobalide as a negative control. The high information density of bilobalide distinguishes it from other scaffolds and may characterize natural product (NP) space more generally. Therefore, we also include a Python script to quickly (ca. 132 000 molecules/min) calculate information content (Böttcher scores), which may prove helpful to identify important features of NP space.

Effect of pH, Anions and Acids on the Extraction of Zinc (II) from Aqueous media using Acetylacetone Solutions of Sulphamethoxazole

The challenge of heavy metal contaminations have been remediated to a certain level by the application of several methods of their extractions from aqueous media. Solvent extraction of zinc (II) ions from buffered aqueous solutions into acetylacetone solution of sulphamethoxazole as a function of pH and concentration of anionic substances and certain mineral acids were investigated in this work. The aqueous medium was prepared by dissolving 1.0995g of ZnSO4.7H2O in 250 ml volumetric flask to form 1000mg/L solution. 50mg/L working concentration was prepared from the 1000mg/L by dilution method. The organic phase is 0.5 M Sulfamethoxazole solution prepared by dissolving 12.664g of the salt in 100 ml acetylacetone. 2 ml each of aqueous and organic phases were taken with micro pipette and transferred into a set of 20 ml extraction bottle and the mixture was agitated mechanically for about 30 minutes. The mixture was allowed to settle and separate into two layers. 1 ml of the aqueous phase was taken, diluted and analysed for Zn (II) ions using atomic absorption spectrophotometer at a wavelength of 213.9. The results obtained on studying the effect of pH showed that Zn (II) ion was quantitatively extracted between pH of 7.0 to pH 8.0. The highest percentage extraction 85.37% was observed at pH 8.0 in acetylacetone solution of sulphamethoxazole. Increase in pH above 8.0 resulted in a steady decrease in the extraction of Zn (II). Studies on the effect of anions showed significant extractions which changes as the anions concentrations increased. All studies on mineral acids also showed significant extractions and increase in the concentrations of the acids affected the percentage extraction. Generally Zinc (II) ions can be extracted quantitatively in mild acids and anions concentrations when buffered from slightly acidic pH ranges of 6.0 to slightly alkaline pH values of 8.5.

Bioimaging of C2C12 Muscle Myoblasts Using Fluorescent Carbon Quantum Dots Synthesized from Bread.

Biocompatible carbon quantum dots (CQDs) have recently attracted increased interest in biomedical imaging owing to their advantageous photoluminescence properties. Numerous precursors of fluorescent CQDs and various fabrication procedures are also reported in the literature. However; the use of concentrated mineral acids and other corrosive chemicals during the fabrication process curtails their biocompatibility and severely limits the utilization of the products in cell bio-imaging. In this study; a facile; fast; and cost-effective synthetic route is employed to fabricate CQDs from a natural organic resource; namely bread; where the use of any toxic chemicals is eliminated. Thus; the novel chemical-free technique facilitated the production of luminescent CQDs that were endowed with low cytotoxicity and; therefore; suitable candidates for bioimaging sensors. The above mentioned amorphous CQDs also exhibited fluorescence over 360–420 nm excitation wavelengths; and with a broad emission range of 360–600 nm. We have also shown that the CQDs were well internalized by muscle myoblasts (C2C12) and differentiated myotubes; the cell lines which have not been reported before.

Clay-Humic Substance Composites for Removal of Pharmaceuticals from Water

Humic substances are the main component of soil organic matter and they actively interact with substances in soils, including pollutants. Humic acid-clay mineral composite materials can be considered as prospective and low-cost sorbents for contaminant removal. The aim of this study is to develop clay mineral and humic acid composite materials and to characterise their possible applications. For this research, montmorillonite, kaolinite and bentonite were saturated with three types of humic substances: technical humic acid from lignite, humic substances extracted from raised bog peat (Latvia) and technical K humate from lignite. Obtained sorbents were characterized using FTIR. The sorption was characterised according to the chosen clay mineral and humic acid type and concentration. Comparing the influence of clay minerals and humic substances on humic matter sorption, it has been found that the sorbed amount of humic substances depend on chosen humic substances and/or clay mineral. Obtained sorbents were used for sorption of chlorpromazine. Results indicate that the most perspective sorbents for chlorpromazine removal are bentonite and bentonite modified with humic acid. However, montmorillonite-humic composites also can be used for removal of chlorpromazine from water.

ДОСЛІДЖЕННЯ ПЕРЕРОБКИ ПРОДУКТІВ УТИЛІЗАЦІЇ ТВЕРДОГО РАКЕТНОГО ПАЛИВА

У сучасних умовах для України актуальним екологічним питанням э утилізація споряджених корпусів двигунів (СКД) із закінченим терміном зберігання. В ході утилізації утворюється полімерна матриця (ПМ) з середнім розміром фрагментів 2 - 15 мм, до складу якої входить до 30% ціклотетраметілентетранітраміна (нітраміна), виробництво якого відсутнє в Україні, його можливо регенерувати із застосуванням диметилсульфоксида (ДМСО). Метою даної роботи є встановлення закономірностей вилучення нітраміну з ПМ за допомогою ДМСО в лабораторних умовах зі зміною такого параметра як масовий модуль (відношення ДМСО: ПМ) в залежності від вологості ПМ. На основі експериментальних даних встановлено залежності масового модуля (відношення ДМСО: ПМ) на ступінь вилучення нітраміна за допомогою ДМСО з ПМ. Найкращим масовим модулем (ставленням ДМСО: ПМ) можна вважати діапазон 2 - 3, що дозволяє досягти ступеня вилучення нітраміни 71,9% (при вологості ПМ 3%). Ідетіфікаціі вилученного з ПМ нітраміна підтверджена ІЧ-спектром і ДТА.

Kinetics Study of Surface Reaction Between Acid and Sandstone Based on the Rotation Disk Instrument

The chemical reaction between acid and rock mineral during the acidizing process is the key point for the acidizing technique. In this study a rotating disk method is used to simulate strata conditions, such as high temperature, high pressure, and acid shear flow reaction. The work investigates the kinetics of the rock acidizing reaction and analyzes the factors effecting the reaction rate, including mineral composition, temperature, pressure, acid concentration, shear velocity, and common-ion effect. The kinetic parameters, such as velocity constant, reaction order, activation energy, and frequency factor, were successfully extracted by curve fitting and the linear regression method. In was shown that hydrochloric acid does not participate directly in the reaction between mud acid (which is a mixture of hydrochloric and hydrofluoric acids) and sandstone mineral but catalyzes the reaction between hydrofluoric acid and sandstone. In this work, the acid rock reaction rate equation has been established, and the impact of the hydrochloric acid catalytic effect has been considered.

Cleaning high-concentration wastewaters left after styrene and propylene oxide production

The goal hereof is to study the process of preparing high-concentration biologically toxic wastewaters for biological treatment. To attain this goal, the following was analyzed: (a) the composition of wastewaters from an operating enterprise; (b) the methods used to treat wastewaters of similar composition; (c) organic substances contained in wastewaters and how they could be removed by extraction. It is shown herein that the wastewater organics can be separated into another phase by reducing pH-altering acidification through introducing concentrated mineral acids into the wastewaters at room temperature and intensive mixing. In addition, the method of extraction was used for a more complete removal of organic substances isolated from the water phase. In this process the extractant in the amount of 5% out of the total wastewaters volume was used. The research quantified the biodegradation-enabling wastewater impurities.

Subcritical water extraction of indium from indium tin oxide scrap using organic acid solutions

Environmental contextIndium is a metal increasingly used in high-technology industries, creating a demand for efficient recycling technology. We investigated extraction of indium from waste using a subcritical water extraction with organic acids. Compared with conventional methods employing concentrated mineral acids, the new method is less corrosive, more efficient and required shorter extraction times. AbstractSubcritical water extraction (SWE) was applied to extract indium (In) from indium tin oxide (ITO) scrap. Four organic acids, acetic acid, gluconic acid, citric acid (CA) and etidronic acid (EA), were used at a solid-to-liquid ratio (S/L) of 10gL−1. Neither acetic acid nor gluconic acid yielded significant extraction of indium. A total of 70.71% and 96.93% of indium was extracted using 1M of CA and EA respectively at 150°C and a final pressure of 18–19 bar within 30min. The extraction efficiency of In was shown to increase with the increase in acid concentration and in temperature. Compared with conventional extraction methods, SWE was more effective using less concentrated acids and required a shorter reaction time.

Proximate components, minerals, amino acids and some anti-nutrients in processed false yam seed meals: Potential benefits for poultry nutrition

Abstract This study investigated the effect of sequential processing techniques (water treatment, chemical treatment and blanching) of false yam seed meal (FYSM) on its proximate composition, mineral and amino acid concentrations and anti-nutritional compounds. Matured false yam (Icacina oliviformis) fruits were harvested and seeds extracted. Five different FYSM samples were prepared. One sample was prepared by crushing fresh false yam seed and sun-drying (Un_T). Four other samples were crushed, each soaked in water (1:2; w/v) for 12 days with water replaced every 3 days. Afterwards, each sample was re-soaked in 1 M concentration of urea (Urea_T), sodium chloride (NaCl_T), sodium hydroxide (NaOH_T) and potassium hydroxide (KOH_T), respectively, for 24 h, washed, blanched and sun-dried to a moisture content of 12%. Sample analysis revealed high dry matter [DM; 89% (NaOH_T) – 93% (KOH_T)] and carbohydrate [71.4% (Un_T) – 83.9% (NaCl_T)] content but a reduction of crude protein from 13.2% (Un_T) to 2.2% (KOH_T). Mineral analysis showed a reduction in Ca from 280 (Un_T) to 24 mg/kg DM (NaCl_T) and in Mg from 52.8 (Un_T) to 13.29 mg/kg DM (Urea_T) but an improvement in K from 110.6 (Un_T) to 368.8 mg/kg DM (KOH_T), in Na [from 558 (Un_T) to 989 mg/kg DM (NaCl_T)] and total P [from 0.31 (Un_T) to 2.37 mg/kg DM (Urea_T)]. Amino acid composition of FYSM was negatively affected by all treatments. Concentrations of anti-nutritional factors, namely total terpenes and saponins, were reduced by 82% (KOH_T) to 92% (Urea_T) and by 68% (KOH_T) to 77% (NaCl_T), respectively. In vitro gas production per 380 mg of sample was similar across treatments. Reducing anti-nutritional factors by sequential use of simple processing methods with easily available chemicals offers the potential to use FYSM in livestock diets. Yet, as some nutrient concentrations are negatively affected, in vivo trials are needed to determine the nutritional value of treated FYSM.