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This paper presents an experimental investigation on the durability properties of metakaolin (MK) and bottom ash (BA) blended geopolymer under different environmental exposure. The blended geopolymer concrete (GPC) was prepared with sodium based alkaline activators under ambient curing temperature. The concentration of sodium hydroxide used was 8 M. The ratio of sodium silicate to sodium hydroxide was kept as 2.0. The performance of blended geopolymer concrete was compared with conventional concrete (CC). The test results reveal that blended geopolymer concrete develops a better performance against sulphate and acid resistance. Also, MK-BA GPC shows enhanced performance over the conventional concrete in terms of sorptivity, rapid chloride and water absorption.

Ultrafiltration (UF) has been increasingly implemented in drinking water treatment plants; however, algae and their secretions can cause severe membrane fouling and pose great challenges to UF in practice. In this study, a simple and practical chemically enhanced backwashing (CEB) process was developed to address such issues using various cleaning reagents, including sodium hypochlorite (NaClO), sodium chloride (NaCl), sodium hydroxide (NaOH), sodium citrate, and their combinations. The results indicate that the type of chemical played a fundamental role in alleviating the hydraulically irreversible membrane fouling (HIMF), with NaClO as the best-performing reagent, followed by NaCl. Furthermore, a CEB process using a combination of NaClO with NaCl, NaOH, or sodium citrate delivered little improvement in the alleviation of membrane fouling compared with NaClO alone. The optimized dosage and dosing frequency of NaClO were 10 mg·L−1 two times per day. Long-term pilot-scale and full-scale experiments further verified the feasibility of the CEB process in relieving algae-derived membrane fouling. Compared with the conventional hydraulic backwashing without chemical involvement, the CEB process can effectively remove the organic foulants including biopolymers, humic substances, and protein-like substances by means of oxidization, thereby weakening the cohesive forces between the organic foulants and the membrane surface. Therefore, the CEB process can efficiently alleviate the algae-related membrane fouling with lower chemical consumption, and is proposed as an alternative to control membrane fouling in treating the algae-containing surface water.

Aims and objectives: In this study, an attempt was made to synthesize, characterize, and develop many applications of functionalized rare metal oxide nanoparticles. Herein, a new strategy for drug delivery is developed to functionalize magnetite nanoparticles to improve their performances in the delivery of celecoxib. Materials and methods: Magnetite Fe3O4@SiO2 nanoparticles are synthesized by the sol-gel method. The surface of the hydroxyl groups was extended by treating with cerium nitrate salt; finally, sodium hydroxide was anchored to the surface hydroxyl groups to produce cerium oxidefunctionalized Fe3O4@SiO2@CeO2 magnetic nanoparticles (FSC). The synthesized sample was characterized by FT-IR, FESEM, VSM, TGA, and XRD. Afterward, the functionalized nanoparticles were examined in the delivery of celecoxib as an active drug model involving cerium oxide and hydroxyl functional groups. Results: For this purpose, the amount of loading/release of the drug was investigated in different amounts of nanocomposite and pH values. Conclusion: The results of the present investigation indicate that the formulations (mFSC=5 mg, pH=3.3) can be considered as best among various formulations with respect to particle size, entrapment efficiency, and in-vitro successful drug release.

Zinc ferrite (ZnFe2O4) nanomaterial can be facilely and conveniently synthesized via the co-precipitation method from aqueous Zn2+ and Fe3+ salt solutions using sodium hydroxide as the precipitant. However, zinc hydroxide is amphoteric and can be soluble at low and high pH values; therefore, the study on pH for simultaneous precipitation of Fe3+ and Zn2+ to achieve pure ZnFe2O4 spinel is essential. In the present study, we elaborate a theoretical equation expressing the relationship between the zinc concentration in complex formation and pH value in the co-precipitation step. Since then, we synthesized ZnFe2O4 spinel and analyzed the products via various techniques such as thermoanalysis (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Vis spectra to investigate the appropriate pH for simultaneous precipitation of Fe3+ and Zn2+. The results indicate that in a wide range of pH values, from 7 to 12, ZnFe2O4 single-phase spinel ferrite structure is formed after calcination of the precipitate at 800 °C, the average particle sizes (SEM, nm) of ZnFe2O4 samples are in the range of 59.5 nm–85.5 nm (but is non-linear change), and their bandgap values are similar, around 1.96 eV. However, the unwanted appearance of α-Fe2O3 phase, the shifting in peak position and the decrease in intensity in the XRD pattern of the spinel products synthesized at pH of 6 and 13, respectively, reflect that the stoichiometric ratio of Zn2+ to Fe3+ in the spinel products is not achieved to 1:2. Such results provide a fundamental basis for choosing the appropriate pH in synthesizing ZnFe2O4 nanoparticles with orientationally structural and optical characteristics.

The synthesis and characterization of sodium titanates (ST), and their evaluation in the photocatalytic reduction of nitric oxide (NO) are described herein. The materials were synthesized by a hydrothermal route using 5 M NaOH as the mineralizer agent and a TiO2 content of 0.06 mg/mL (expressed as the mass ratio of TiO2/mL of NaOH), at 170 °C for 48 hours, resulting in sodium tri- and hexa-titanates. A nanotubular morphology was observed for the ST, as proved by scanning electron microscopy (SEM); a subsequent heat-treatment at 400 °C allowed a complete transformation of sodium tri- to hexa-titanates and an increase in bandgap. The obtained ST were impregnated with Ag+ and Zn+ cations, ST-Ag and ST-Zn, respectively, to tune the materials’ bandgap. XPS analysis of the ST-Ag materials showed evidence of metallic Ag, pointing to the formation of silver nanoparticles, whereas for ST-Zn oxide phases were mainly spotted. The materials were evaluated for the photocatalytic reduction of NO using a reactor fed with a continuous flow rate of NO, generated in situ at a flow of 280 mL/min using nitrogen and a 253 nm UV irradiation source. The photocatalytic tests showed that pristine ST (tri- and hexa-titanates) displayed better performance in the reduction of NO with respect to the impregnated samples (ST-Ag, ST-Zn). Maximum degradation efficiencies of 80% were achieved when 1 g of photocatalyst was used with a flow of 280 mL/min and a 253 nm UV lamp.

The traditional sodium desulfurization process for waste lead-acid batteries is beneficial to the environment; however, it is limited by poor economic viability as the cost of desulfurizer is much higher than the value of desulfurization by-products. This study proposes a new closed-loop pre-desulfurization process for lead paste, which consumes only lime as the indirect desulfurizer, produces sodium sulfate as a by-product, and regenerates sodium hydroxide as the direct desulfurizer. The concentration of prepared sodium hydroxide reached 2.57 mol/L when the reaction was conducted at room temperature for 2.0 h, with a sodium oxalate: calcium oxide molar ratio of 1:1.3, a CaO: water mass ratio of 1:6, and magnetic stirring at 600 rpm. Cost estimation and economic analyses were also conducted. The cost of lead paste generated by this new pre-desulfurization process was 37.62 dollars/ton lower than traditional high-temperature smelting, and 44.42 dollars/ton lower than direct sodium pre-desulfurization. Thus, this process provides a practical and feasible clean recycling method for waste lead-acid batteries with significant environmental and economic benefits.

Herein, we report an efficient, environmentally friendly and stable catalyst development to hydrogen evolution from sodium borohydride hydrolysis. For this purpose, Ruthenium complex catalyst successfully fabricated via 5-Amino-2,4-dichlorophenol-3,5-ditertbutylsalisylaldimine ligand and RuCl3·H2O salt. Ru complex catalyst was identified with X-Ray Diffraction Analysis, Infrared Spectroscopy, Elemental Analysis, Transmission electron microscopy, Scanning Electron Microscope and Brunauer-Emmett-Teller Surface Area Analysis. According to the analysis results, it was confirmed that Ru complex catalyst was successfully synthesized. Ru complex was used as a catalyst in NaBH4 hydrolysis. The kinetic performance of Ru complex catalyst was evaluated at various reaction temperatures, various sodium borohydride concentration, catalyst concentration and sodium hydroxide concentration in hydrogen evolution. The apparent activation energy for the hydrolysis of sodium borohydride was determined as 25.8 kJ mol−1. With fully conversion, the promised well durability of Ru complex was achieved by the five consecutive cycles for hydrogen evolution in sodium borohydride hydrolysis The hydrogen evolution rates were 299,220 and 160,832 mL H2 gcat−1 min−1 in order of at 50 °C and 30 °C. Furthermore, the proposed mechanism of Ru complex catalyzed sodium borohydride hydrolysis was defined step by step. This study provides different insight into the rational design and utilization and catalytic effects of ruthenium complex in hydrogen evolution performance.

Keeping in view of the hazardous effects of production of Ordinary Portland Cement (OPC) on the environment, it is necessary to minimize the usage of OPC and subsequently replace it by the alternative materials which possess the binding properties. One such attempt led to discovery of geopolymer concrete. In present study, Alumina Refinery Residue (ARR) and slag from iron industry (GGBFS) are the two binder materials used in the ratio of 25:75 (ARR: GGBFS) along with the combination of Sodium Hydroxide and plagioclase-based alkali activator for initiating polymerization reaction. Present study focuses on evaluation of performance of geopolymer concrete in terms of Compressive Strength and Acid Durability Factor. Test results revealed that 28 days compressive strength of geopolymer concrete was found to be 38.37 N/mm2 and that for NCC was 35.32 N/mm2. It is also observed that the percentage weight loss and strength loss after 120 days of immersion of the specimens in 10% HCl solution, was found to be 11.133% and 13.526% for GPC and that for NCC was found to be 13.504% and 21.347% respectively. Results of Acid Durability Factor proved that GPC specimens were found to perform 7.82 times better than NCC specimens. Further, Scanning Electron Microscope technique was used to analyze microstructure of both GPC and NCC specimens. Micro analysis results also showed that GPC specimens prove to be better than NCC specimens. The present study significantly determines the performance of GPC specimens produced by the combination of Sodium Hydroxide and Plagioclase based activator for initiating polymerization reaction. Generall, In this study, sodium/potassium based silicate compound in the alkali activator part is completely replaced by Plagioclase based activator (in the powder form) in order to have better mechanical, durable and microstructure properties, resulting to a economic mix for massive applications.

In this paper, novel composite materials based on white carbon black were synthesized and used to prepare high-performance electrode materials. First, white carbon black was activated by sodium hydroxide (NaOH) to remove the impurities, and the specific surface area of activated white carbon black could be increased to load other conductive materials. Second, the activated white carbon black was respectively mixed with lithium carbonate (Li2CO3) and manganese dioxide (MnO2) with different mass ratios. Subsequently, those composite materials were heated to a paste, which were coated on a foam nickel sheet to obtain nickel electrode. Finally, laser particle size, X-ray diffraction (XRD), scanning electron microscope (SEM), and the electrochemical techniques were applied to characterize those white carbon black composites. On the one hand, when the ratio of white carbon black to Li2CO3 was 1:1, almost no impedance was observed, and the electrochemical performance was the best. On the other hand, the electrochemical performance was the best when the ratio of white carbon black to MnO2 was 1:2. White carbon black-based materials with high specific surface area could be prepared via one step by activation of white carbon black by NaOH. This method was simple to operate and showed the advantage of low cost as well as industrial application potential.

In this study, a new metallurgical system for treating electrolytic manganese anode sludge by microwave roasting and alkaline leaching system was developed, and the lead leaching behaviour was studied. The XRD results show that Pb in anode sludge is mainly in the form of PbSO4 after microwave roasting at 850°C, as a result, the leaching rate of Pb is improved. The results show that the leaching rate of lead can reach 93.89% under the conditions of liquid-solid ratio of 7:1, leaching time of 30 min, leaching temperature of 40°C, and the concentration of sodium hydroxide of 8%. The addition of tartaric acid can further improve the lead leaching rate, FT-IR analysis showed that the coordination form of lead and tartaric acid. Lead and tartaric acid ions (L) form three coordination compounds, PbL, Pb2L2 and Pb2L3, which can only exist in alkaline solution.

Efficient and environmentally friendly tin leaching methods are of significant interest for the separation and recovery of tin from various materials such as tin-plated scraps and waste printed circuit boards. In this study, we investigated the oxidative dissolution of metallic tin in an alkaline solution. A pure tin specimen was leached at 30 °C using different oxidizing agents in a 1 M sodium hydroxide solution. The results demonstrated that iodate ion (IO3−) is one of the most effective oxidizing agents for dissolving tin in alkaline media. A fundamental mechanism for tin dissolution into the leaching solution containing IO3− is proposed based on electrochemical measurements. In addition to the rapid dissolution of tin without much heating, the benefits of using IO3− as an oxidizing agent include its electrochemical regenerability. Thus, alkaline leaching using IO3− as an oxidizing agent is a potentially efficient technique for separating and recovering tin.

Caustic wash is one of many industrial processes that are used to produce jet fuel. In this study, an analysis of the key parameters of the kerosene caustic wash process was conducted to improve the total performance of the treatment process. The investigated parameters are caustic concentration (from 0.03 to 3.0 wt%), caustic volume (from 110% of theoretical to 250%), number of treatment stages (one and two stages), wash water type (demineralized water and alkaline soft water), and wash water volume (10% and 30% of kerosene feed volume). Results revealed that the reaction between sodium hydroxide and naphthenic acids is a diffusion-controlled chemical reaction. The diluted caustic solutions (0.5 wt%) are better than the concentrated ones (3 wt%). Higher excess caustic volume has a slight effect on kerosene acidity. Performing the caustic treatment process in one stage is sufficient, and the two-stage process has no effect on acidity. Washing caustic-treated kerosene with demineralized water (pH=7) has a slight adverse effect on kerosene acidity. Increasing the demineralized water volume results in a slight increase in the acidity of the treated kerosene. Wash water should be slightly alkaline (pH 7.5–8) to prevent the reverse reaction of sodium naphthenates back into naphthenic acid. Increasing wash water volume (more than 10 vol% of kerosene feed) has no noticeable effect on the water content of treated kerosene.

The paper discusses various ways of activating phosphorus slags by introducing additives for the development of phosphorus slag binders (PSB), replacing cement. Considering that pseudowollastonite is the main mineral of phosphorus slags and without activating components does not possess the binding properties necessary for the production of building materials based on them, we used compositions of small amounts of sodium hydroxide with alkali metal salts, the anions of which form poorly soluble compounds with calcium. When choosing activating components, scarce alkaline additives were replaced by waste from chemical plants, which allows a passing solution of their practical use and environmental problems. The strength at a sodium hydroxide content of 1–4 % after curing of slag samples of various batches was in the range of 50.0–70.0 MPa. Samples of binders of normal hardening at the age of 28 days with a sodium hydroxide content of 0.5; 1.0, 2 and 4 % had the strength of 20.3; 35.4; 45.6; 55.8 MPa, respectively. The effect of the combined presence of alkali and salt is especially noticeable for small amounts of sodium hydroxide. Binders containing a composition of cement with salts under normal conditions and after curing showed a slightly lower strength than in an alkaline medium. With a constant cement content (4 %), the strength indicators increase with an increase in the proportion of the salt additive, reaching at 4 % its maximum value. The effect of the nature of activators on pH was determined. The data obtained indicate the advantages of using PSB and various industrial wastes with a low content of alkaline compounds in the production, В работе рассматриваются различные способы активации фосфорных шлаков путем введения добавок для разработки фосфорношлаковых вяжущих (ФШВ), заменяющих цемент. Учитывая, что псевдоволластонит является основным минералом фосфорных шлаков и без активирующих компонентов не обладает связующими свойствами, необходимыми для производства строительных материалов на их основе, мы использовали композиции из небольших количеств гидроксида натрия с солями щелочных металлов, анионы которых образуют плохо растворимые соединения с кальцием. При выборе активирующих компонентов ограниченные щелочные добавки были заменены отходами химических производств, что позволяет попутно решить проблемы их практического использования и защиты окружающей среды. Прочность при содержании гидроксида натрия 1–4 % после тепловлажностной обработки образцов шлака различных партий находилась в пределах 50,0–70,0 МПа. Образцы вяжущих нормального твердения в возрасте 28 суток с содержанием гидроксида натрия 0,5; 1,0, 2 и 4 % имели прочность 20,3; 35,4; 45,6; 55,8 МПа соответственно. Эффект совместного присутствия щелочи и соли особенно заметен для небольших количеств гидроксида натрия. Вяжущие, содержащие композицию цемента с солями, в нормальных условиях и после ТВО показали несколько меньшую прочность, чем в щелочной среде. При постоянном содержании цемента (4 %) показатели прочности увеличиваются с увеличением доли солевой добавки, достигая при 4 % своего максимального значения. Было определено влияние природы активаторов на рН. Полученные данные свидетельствуют о преимуществах использования ФШВ и различных промышленных отходов с низким содержанием щелочных соединений в производстве., У роботі розглядаються різні способи активації фосфорних шлаків шляхом введення добавок для розробки фосфорношлакових в'яжучих (ФШВ), що замінюють цемент. Враховуючи, що псевдоволластоніт є основним мінералом фосфорних шлаків і без активуючих компонентів не володіє в'яжучими властивостями, необхідними для виробництва будівельних матеріалів на їх основі, ми використовували композиції з невеликих кількостей гідроксиду натрію з солями лужних металів, аніони яких утворюють важкорозчинні сполуки з кальцієм. Під час вибору активуючих компонентів обмежені лужні добавки були замінені відходами хімічних виробництв, що дозволяє попутно вирішити проблеми їхнього практичного використання і захисту навколишнього середовища. Міцність при вмісті гідроксиду натрію 1–4 % після тепловологісної обробки зразків шлаку різних партій перебувала в межах 50,0–70,0 МПа. Зразки в'яжучих нормального твердіння у віці 28 діб з вмістом гідроксиду натрію 0,5; 1,0, 2 і 4 % мали міцність 20,3; 35,4; 45,6; 55,8 МПа відповідно. Ефект спільної присутності лугу і солі особливо помітний для невеликих кількостей гідроксиду натрію. В'яжучі, що містять композицію цементу з солями, в нормальних умовах і після ТВО показали дещо меншу міцність, ніж в лужному середовищі. При постійному вмісті цементу (4 %) показники міцності збільшуються зі збільшенням частки сольової добавки, досягаючи при 4 % свого максимального значення. Було визначено вплив природи активаторів на рН. Отримані дані свідчать про переваги використання ФШВ і різних промислових відходів з низьким вмістом лужних сполук у виробництві.

Alkali-oxygen one-bath scouring and bleaching process of the flax roving was studied by using a new type of synthesized non-silicon oxygen bleaching stabilizer Poly(acrylic acid) magnesium instead of sodium silicate. Based on the analysis of the effects of single factors such as sodium hydroxide concentration, hydrogen peroxide concentration, temperature, time and the amount of the synthesized non-silicon oxygen bleaching stabilizer poly(acrylic acid) magnesium salt on the performance of the bleached flax roving, including the whiteness, the breaking tenacity, the capillary effect and the weight loss ratio. The optimal process for the application of the stabilizer was determined by orthogonal test, namely, hydrogen peroxide concentration 8.5 g/L, sodium hydroxide concentration 5 g/L, sodium bisulfite 3 g/L, sodium carbonate 3 g/L, the synthesized non-silicon oxygen bleaching stabilizer poly(acrylic acid) magnesium 5.5 g/L, scoured and bleached at 90 °C for 60 min, and the bath ratio was 25:1. Compared with the traditional oxygen bleaching stabilizer sodium silicate, it not only has good ability to inhibit the rapid decomposition of hydrogen peroxide, but also has the advantages of higher whiteness, higher capillary effect, good feel and breaking tenacity, and can effectively solve the "silicon scale" problem and improve the quality of flax products. A novel non-silicon oxygen bleaching stabilizer poly(acrylic acid) magnesium was synthesized and successfully applied to alkali-oxygen one-bath scouring and bleaching process of the flax roving, effectively solving the "silicon scale" problem caused by conventional sodium silicate as stabilizer.

The paper provides the results of experiments on the hydrometallurgical processing of finely dispersed technogenic raw materials for primary aluminum production in Soderberg cells (case study of the Irkutsk Aluminum Smelter) – aged sludge. The components of this sludge are dust from electrostatic precipitators (79.7 %), wet gas cleaning sludge (4.4 %) and coal froth flotation tailings (15.8 %). According to the grain-size analysis carried out, aged sludge sample particles have a size of –50 μm. According to the chemical composition analysis of the sludge sample, main components in it are carbon, cryolite, chiolite with a small amount of other compounds (corundum, ralstonite, spodumene, fluorite). Fluorine leaching experiments were carried out with a 2 % sodium hydroxide solution at a stirrer speed of ~1020 rpm. Using the mathematical planning of a three-factor experiment, it was found that the maximum concentration of fluorine in the solution (15.844 g/dm3) is achieved with the following optimal parameters of fluorine alkaline leaching: temperature of 90 °C, liquid-to-solid ratio of 9 : 1, and time of 90 min. The multidimensional polynomial equation was obtained for fluorine alkaline leaching from aged sludge. Cryolite was obtained from fluorine-containing solutions (by the reaction of sodium fluoride interaction with sodium bicarbonate and an aluminate solution), which was confirmed by X-ray phase analysis data.

The optimal technological parameters for the production of caustic soda from sodium carbonate and sulfate and calcium hydroxide have been established. The influence of the concentration of lime milk on the rate of filtration by sediment and filtrate has been studied. Purpose of the Work: The purpose of this work is to determine the physicochemical basis for the production of sodium hydroxide and burkeite by causticization of sodium carbonate and sulfate. Scientific Novelty: In comparison with the known works, a theoretical profoanalytical analysis of the one-cation of four-component system and its constituents was carried out for the first time, and also determined the optimal technological parameters of causticization of solutions for local carbonates and sodium sulfates. Features of the Work: - the influence of the main technological parameters on the processes of causticization, filtration, evaporation; - research of intermediate and finished products by modern physicochemical methods; - study of the rheological properties of the solution depending on the temperature and concentration of the resulting solutions.

Owing to the increasing ACW generation, asbestos detoxification and recycling technologies are required for environmental and economic reasons. Recently, microwave heat treatment is being considered an efficient method for ACW detoxification. In the present study, ACW is detoxified through a microwave heat treatment involving SiC plates. These plates absorb the microwaves and radiate the heat, thereby enhancing the heat treatment efficiency relative to those of existing methods, in which the microwave heat treatment method requires a temperature higher than 1100 °C. In the present study, thermochemical experiments were conducted by applying chemical additives during the microwave heat treatment. To determine the optimal heat treatment temperature based on the chemical added, the detoxification response of the ACW as a function of heat treatment was investigated for different chemical additives, and the crystal structure and microstructure changes were analyzed using X-ray diffraction and scanning electron microscopy. ACW was then detoxified by applying the optimal temperature derived for each chemical additive in microwave heat treatment involving SiC plates. According to the results, asbestos is eliminated in the ACW at 800 and 900 °C with magnesium chloride and sodium hydroxide, respectively, as the additives.

It is of great practical significance to manufacture ceramic membranes with good reusability. We used a macromolecular gel network for in situ enhancement of a reticulated skeleton ceramic (RSC) membrane. The prepared RSC membranes were firstly characterized to determine their physical and chemical properties. The sample calcined at 1400 °C has a porosity of 41.66 %, a pore size of 0.34 μm, a mechanical strength of 4.53 MPa, and a permeability of 63.92 L m−1 h−1 bar−1. This membrane can effectively reduce the content of total organic carbon (TOC) (80 %) and calcium ion (>85 %). In addition, the flux of RSC fouled by alginate, calcium ions, or their mixture is effectively recovered by simple chemical rinsing using sodium hydroxide and ethylenediaminetetraacetic acid.

The effect of aqueous extract of leaves of Morinda tinctoria on the corrosion inhibition of aluminium in alkaline medium was studied by weight loss and electrochemical methods such as electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The change in different parameters like concentrations of inhibitor, sodium hydroxide, halide ions, temperatures and immersion time was carried out to determine the longevity and stability of the inhibitor. Increase in the immersion time, alkaline concentration and temperature increases the inhibition efficiency. Investigation of temperature studies reveals that the inhibitor follows chemisorption behaviour towards corrosion protection. Temkin adsorption isotherm was obeyed throughout the corrosion inhibition process. The added halide additives produced tremendous changes in the inhibition system. The recorded scanning electron microscopy for the aluminium metal before and after the addition of inhibitor in the alkaline medium confirmed the adsorption of inhibitor molecules on the metal surface. The investigation proves that the inhibitor works perfectly against the corrosion of metal and suitable for corrosion inhibition process.

In this study, removal of copper from synthetic aqueous solution was done using adsorption process. The batch study was done at room temperature and analyzed using Freundlich and Langmuir isotherms. The Box–Behnken design method of response surface methodology was used to know the interactions between independent variables (pH of aqueous solution, contact time, adsorbent dose, and initial copper concentration) and response variable (copper removal). The activated Ganga sand was used as an adsorbent to make treatment in a cost-effective way. The Ganga sand was activated by using a base solution of 14 N sodium hydroxide. The synthetic aqueous solution was having copper concentration of 100 ppm. The optimum conditions for independent variables to achieve maximum removal of copper from synthetic aqueous solution were also determined. The optimum conditions of aqueous solution for pH, contact time, adsorbent dose, and initial copper concentration were obtained as 8.7, 150 min, 3.5 g/L, and 34 ppm respectively. At this optimum condition, 97.7% of copper removal was achieved. Both isotherms (Freundlich and Langmuir isotherms) were found fitted well with a good correlation coefficient (R2 > 0.95). The kinetic behavior for the responsible adsorption process was analyzed using pseudo-second-order kinetic equations. The results suggested that Ganga sand can be used as a promising economical and conventional adsorbent for copper removal.

International audience; The relationship between concentration of sodium cations and the properties of faujasite (FAU) zeolite using a two-step synthesis procedure including (1) formation of amorphous aluminosilicate precursors and separation of amorphous nanoparticles, and (2) transformation of these amorphous particles into zeolite crystals by treatment with alkali solutions (NaOH) were studied. Three representative samples including two nano-sized zeolites and one micron-sized zeolite were prepared using different concentration of sodium hydroxide. The crystallization process of these zeolites was studied in details by FTIR, NMR, XRD, SEM, TEM, N 2 adsorption. The results indicated that minor changes in the concertation of inorganic cations can significantly shorten the induction period and crystallization time and thus affect the morphology, size and chemical composition of the zeolite crystals.

The behavior and mechanism of Li leaching from lithium aluminum silicate glass-ceramics which can be used as a secondary source of Li using aqueous NaOH solution was investigated. The Li leaching efficiency is increased with increasing concentration of NaOH, specific surface area, and reaction temperature. When leached under optimum conditions, 2 mol/L NaOH, 53 μm particle undersize, 1:10 solid/liquid ratio, 250 r/min stirring speed, 100°C reaction temperature, 12 hr, the Li leaching efficiency was approximately 70%. However, when the leaching experiment was performed for 48 hr, the concentration of Li+ ions contained in the leach liquor decreased from 1160 to 236 mg/L. To investigate the origin of this phenomenon, the obtained leach residue was analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. These analyses show that zeolite was formed around the lithium aluminum silicate glass-ceramics, which affected the leaching of by adsorbing Li+ ions. In addition, using the shrinking-core model and the Arrhenius equation, the leaching reaction with NaOH was found to depends on the chemical reaction of the two reactants, with a higher than 41.84 kJ/mol of the activation energy.

By the interaction of cobalt(II) chloride, sodium hydroxide, and pentafluorobenzoic acid (Hpfb) in water the first heterometallic complex of cobalt with pfb– anions is obtained. According to the X-ray crystallographic analysis, the complex is a cationic 1D polymer with the general formula {[Na2Co(pfb)2(H2O)8](pfb)2}n.

The main objective of this research is to generate the hydrogen gas as a fuel and part of hydroxy gas (HHO) from the drinking water (H2O) using electrolyzing method with a different electrolytes such as sodium hydroxide (NaOH), sodium carbonate (Na2CO3), and Vinegar in HHO generator for best results, the practical examinations were done by a generator that designed and built for this purpose using plate electrodes, with a rechargeable 12-volt battery and the produced gas was measured at each case and used as a fuel for operating a small single-cylinder spark-ignition engine (Honda G 200) with taking into account the safety precautions. The results show that increasing the ratio of (NaOH) grams/liter of H2O increases the gas production, while the other two electrolytes (Na2CO3 and vinegar) are not effecting too much, and using the mixing procedure (%) of the electrolytes (NaOH with Na2CO3) and (Na2CO3 with Vinegar), it is observed that the HHO generation noticeable increases with increasing the mixing ratio of the first mixture and not too much with the second.

The present study aims to improve the impurity removal step in the rare-earth elements (REE) processing. The fast-growing demand for REE in recent years has attracted special attention to their extraction process. Most of the operating cost associated with the extraction of REE is concentrated in the hydrometallurgical processing of the ores or concentrates. The purity of the final REE product is a valuable key factor to the market. Therefore, impurity removal is an important step in the REE process circuits. This study focuses on improving the neutralization process of sulfate-based REE pregnant leach solutions (PLS), more specifically the Fe and Al removal step. Despite some studies, the mechanism of REE loss during neutralization and impurity removal is still not well understood. Different reagents such as lime, magnesium hydroxide, and sodium hydroxide were investigated in batch experiments. Tests with NaOH presented the minimum REE loss: 17.6% Ce, 20.9% Nd, 24.3% Tb, and 28.8% Er. Tests with Ca(OH)2 led to highest REE loss values: 33.7% Ce, 42.7% Nd, 42.9% Tb, and 51.6% Er. However, calcium-based reagents offer the greatest economic benefit, owing to their low cost. Therefore, further tests were carried out with Ca(OH)2 addition to PLS with varying Fe and Al concentrations. REE loss of 16.3% Ce, 17.6% Nd, 5.8% Tb, and 4.5% Er were registered when 4.0 g/L Fe and 4.0 g/L Al were available in the solution, and the pH was increased from 1.0 to 3.2, which was the largest REE loss. The lowest REE loss (4.0% Ce, 4.3% Nd, 0.7% Tb, and 0.6% Er) was observed when the PLS contained 0.5 g/L Fe and no Al. A two-step impurity removal process was proposed based on the results of this study to remove Fe and Al from the REE PLS. Gypsum–Al–Fe residues produced from the neutralization steps were further treated in an acid leaching step to recover above 80% of the lost REE and improve the efficiency of the process.

In the present work, we report the successful extraction of high purity silica from the Algerian siliceous sand. We improved the chemical extraction process of silica using acid pretreatment before purification and studied the effect of sodium hydroxide (NaOH) solution molarity on the purity of as-obtained silica. X-ray diffraction, Energy-dispersive X-ray spectroscopy, and Scanning Electron Microscopy analyses were carried out on the samples before, during, and after chemical purification. The results show the improvement of the purity of the resulting powder with the change of the alkaline concentration. The results showed a decrease in the impurity concentration of the sand after acid leaching. The extracted silica has a purity of more than 99% and has an amorphous and mesoporous nature, confirmed by the mentioned analysis techniques, together with Fourier Transform Infrared Spectroscopy, thermogravimetric analysis, and the Physical Adsorption Analysis, which makes our chemical extraction method very promising, and the resulted silica is a good source to elaborate solar grade silicon used in photovoltaic applications.

Activated carbon (AC) has attracted attention among researchers due to special properties such as high porosity, highly adsorption and low cost. In this research, activated carbon has been successfully produced from the coconut shell by using the chemical activation which are zinc chloride (ZnCl2), phosphoric acid (H3PO4)and sodium hydroxide (NaOH) as the activating agent. The optimum parameter for the power of microwave radiation used was 380 W, impregnation ratio of activating agent to char was 3: 1 for H3PO4, 2:1 for NaOH, and for 1:1ZnCl2 while concentration of each activating agents was 0.5M. The activation time that were implemented was 10 minutes using microwave radiation method. All samples then characterized using, FTIR, XRD and TGA in order to determine the functional groups, composition and element and weight loss of the activated carbon. The XRD results showed that the activated carbon that had been produced were amorphous. In the FTIR – ATR , the there were C = C bonds and phenyl ring existed in the activated carbons. In TGA results, it indicated that the activated carbon has very high resistant to weight loss compared to char, which range temperature were same. The result showed that phosphoric acid has the most significant effect on the synthesized AC properties since the moisture content was low and the highest yield percentage.

A simple eco-friendly process is proposed to retrieve tin from waste printed circuit boards (WPCBs) as tin oxide nanostructured powders. The WPCBs were leached in disodium salt of ethylene diamine tetraacetic acid (Na2-EDTA) chelating agent comparing results with acid leaching. Parameters affecting the leaching process such as sample particle size, pH, temperature, time, liquid/solid ratio, and concentration of Na2-EDTA were investigated. A 100% of Sn can be recovered by leaching in 0.1 mol/L Na2-EDTA solution for 3 hours at 80 °C with optimum conditions of pH: 5, liquid/solid ratio: 30, particle size −0.07 mm, and constant stirring of 400 rpm. Kinetic data suggest a diffusion-controlled process as the rate-determining step for the Na2-EDTA extraction of tin from WPCBs with an activation energy of 15.28 KJ·mol−1. Selective precipitation of Sn as tin oxide (SnO2) nanoparticles (NPs) from leachant solution was performed via a simple route using sodium hydroxide. Characterization tests (XRD, FTIR, EDX, FE-SEM, and TEM) were made to confirm the morphology of the nanoparticles. The prepared SnO2 NPs, having a size range of 8–12 nm, showed an excellent photocatalytic action towards methylene blue (MB) dye under ultraviolet (UV) light illumination with 90% efficiency after 180 min and showed good reusability after five consecutive cycles.

Background and objective: Antacids are basic substances that can neutralize hydrochloric acid and reduce gastric acidity. They are over the counter drugs used to treat dyspepsia. The most commonly used antacids are sodium bicarbonate, magnesium hydroxide, aluminum hydroxide, and calcium carbonate. This study aimed to evaluate the effectiveness of antacids that are commonly used in Erbil city by finding their acid-neutralizing capacity. Methods: The method for acid-neutralizing capacity was adapted from pharmacopeia. The samples were prepared by dissolving the antacid in an excess amount of hydrochloric acid, then neutralizing the excess acid with sodium hydroxide solution by doing back titration. The number of milliequivalents that are neutralized by the antacid is the acid-neutralizing capacity of the antacid. Results: Rennie® chewable tablet showed the highest acid-neutralizing capacity, followed by AntacidAwa and Maalux® plus. The lowest acid-neutralizing capacity was for the suspensions Gaviscon® and Enoxon®. Conclusion: Acid-neutralizing capacity is an easy and quick method to evaluate the efficacy of antacids. Different combinations of salts and concentrations can affect the acid-neutralizing capacity of the antacid. The higher the neutralizing effect of the antacid, the more effective the antacid is. Keywords: Acid-neutralizing capacity; Antacid; pH; Dyspepsia; Erbil.

Hydrogen is a sustainable, renewable and clean energy carrier that meets the increasing energy demand. Pure hydrogen is produced by the hydrolysis of sodium borohydride (NaBH4) using a catalyst. In this study, Ni/TiO2 catalysts were synthesized by the sol-gel technique and characterized by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) methods. The effects of Ni loading ratio (20–40%), catalyst amount (75–200 mg), the concentration of sodium hydroxide (NaOH, 0.25–1 M), initial amount of NaBH4 (75–125 mg) and the reaction temperature (20–60 °C) on hydrogen production performance were examined. The hydrogen yield (100%) and hydrogen production rate (110.87 mL/gcat.min) were determined at the reaction conditions of 5 mL of 0.25 M NaOH, 100 mg NaBH4, 100 mg Ni/TiO2, 60 °C. Reaction order and activation energy were calculated as 0.08 and 25.11 kJ/mol, respectively.

Piezochromic luminescent materials have shown great potential in advanced optoelectronic applications. However, most of luminescent materials usually undergo emission quenching under external stimuli. Herein, we demonstrate for the first time that the photoluminescence of carbon dots (CDs) confined within sodium hydroxide can be enhanced when high pressure is applied. They exhibit a 1.6-fold fluorescence enhancement compared with pristine CDs. Importantly, the enhanced fluorescence intensity can be retained after the release of pressure to ambient conditions. A combination of experimental analysis and theoretical simulations indicates that such an enhanced emission is mainly attributed to the strong confinement resulting from the sodium hydroxide matrix, which can separate the CDs spatially and restrict the nonradiative pathway. These results provide a rational strategy for manipulating the optical properties of CDs with enhanced and retainable photoluminescence (PL) performance, thus opening up a venue for designing luminescent CDs-based materials.

Pyrolysis is an effective way to process waste of the pulp and paper industry, in particular, sludge-lignin, which makes it possible to obtain a commercial product – a carbon adsorbent. The method of thermochemical activation using sodium and potassium hydroxides is now widely used in pyrolysis of wood waste processing. This method enables the production of carbon nanostructured materials with high adsorption properties, especially when adsorbed from the liquid phase. The paper studies the influence of conditions for the synthesis of carbon adsorbents of sludge-lignin on their adsorption properties using sodium hydroxide as an activating agent. Sludge-lignin was obtained under laboratory conditions by treating lignin-containing wastewater with aluminum oxychloride coagulant. We applied the method of the planned experiment: a rotatable central composite design of the second order for three factors. We studied the influence of the main factors determining the adsorption properties of coals, namely, temperature, pyrolysis duration and sodium hydroxide dosage, on the values of output parameters characterizing the adsorption efficiency from the liquid phase, i.e. the iodine number and the adsorption capacity of methylene blue removal. We obtained experimental data, which were used to construct response surfaces illustrating the influence of the experimental factors on the output parameters. The positive effect of pyrolysis temperature and alkali dosage on the adsorption properties of the synthesized coals was found. The following results were obtained: the adsorption activity for iodine – 300 %, for methylene blue – 1000 mg/g; indicating a developed micro- and mesoporous surface and the possibility of using these compounds for adsorption of both gases and vapors, and organic substances from solutions. Therefore, samples of activated carbons synthesized from sludge-lignin were tested as lignin adsorbents of lignin-containing wastewater. The obtained dependences correlate well with the data describing the influence of pyrolysis parameters on the coal adsorption capacity of methylene blue removal. The high efficiency of adsorbents of sludge-lignin in the removal of lignin from solutions was shown. The value of the specific adsorption was about 1500 mg/g. For citation: Vorontsov K.B., Bogdanovich N.I., Sedova E.L., Solovyova P.V. Formation of Adsorption Properties of Carbon Nanostructured Materials by Thermochemical Activation of Sludge-Lignin. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 4, pp. 181–189. DOI: 10.37482/0536-1036-2021-4-181-189

Hydrometallurgical recycling of spent lithium cathode material commonly uses sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) as reagents for impurity removal, metal extraction, and lithium re...

The presence of arsenic in base metal concentrates including copper, lead, and zinc creates problems such as low quality of final product and environmental issues. Therefore, additional processing steps for removing arsenic are required. Among several methods to reduce arsenic from these concentrates, alkaline leaching was selected as an efficient and simple method. In this research, sodium sulfide and sodium hydroxide mixtures were used for arsenic elimination from lead concentrate produced by Zarrin Madan Asia Company. To obtain optimum conditions, the effect of some parameters such as temperature, leaching time, liquid/solid ratio (L/S), sodium sulfide, and sodium hydroxide concentrations on arsenic removal was investigated. Based on characterization methods, mimetite was the main arsenic compound in lead concentrate; however, after alkaline sulfide leaching, the starting material was decomposed, and lead was mainly transformed to PbS. Accordingly, up to 98% of arsenic was removed under optimum selective leaching conditions (30 g/L of sulfide sodium, 5 g/L of sodium hydroxide, at 85 °C, 15 min, and L/S ratio = 7). To immobilize arsenic from alkaline leaching, the precipitation method was used by finding optimum conditions (at Fe/As = 3, 25 °C and 12 h). Therefore, the final product was suitable for further smelting processes without any environmental problems.

This article studies inorganic components in Heliánthus tuberósus stems. Ash samples and extracts obtained at different pH values were examined. It is established that the extractant's nature has a significant effect on the yield of extractive substances from the ground stems: the greatest (45%) and the minimum (31%) yield was achieved by sodium hydroxide and distilled water, respectively. According to atomic absorption spectrometry, the main ions in the extracts obtained in different media are those of potassium, calcium, sodium, magnesium and iron. Following treatment of stems with solutions having different pH values, the mass fraction of ash varied from 0.4 to 2.3%. The smallest ash yield was observed for a stem sample after acid extraction. According to energy dispersive X-ray fluorescence spectrometry, all ash samples contained predominantly K, Ca, Si and P compounds. Acid hydrolysis produced the highest level of Si in samples, which allows this ash to be used as a silicon-containing material. The ash components of the core and outer part of the stem were compared with the initial sample. According to the nature of thermal decomposition, the initial sample and the outer shell were similar between themselves, though differing from the core. The ash content of the initial sample was 4.3%, with the ash content of the stem core being ~2 times higher than that of the outer shell (7 and 3.8%, respectively). The results of IR spectroscopy showed that splitting of bands in the IR spectra of ash samples depend on the part of the stem and the pre-treatment of raw materials at different pH values. The ash of the initial sample, core and outer shell, as well as the ash of the residues after the aqueous and alkaline hydrolysis of the stem, showed the absorption bands of carbonate groups. The IR spectra of the stem ash after acid extraction contained absorption bands characteristic of amorphous silicon dioxide. According to the conducted X-ray analysis, the studied ash samples were in an amorphous-crystal and crystalline state. The identification of phases was carried out.

Chromic oxide (Cr2O3) is one of the most important chromic salts and is widely used in industrial applications. Traditionally, Cr2O3 is prepared from chromium trioxide (CrO3) or sodium dichromate (Na2Cr2O7), both of which are manufactured from chromite ore. However, traditional manufacturing processes are time-consuming, inefficient, and energy-consuming, and they can catheuse severe environmental pollution by discharging large quantities of solid residues containing Cr in the form of Cr(VI) compounds. These compounds are also harmful to human health. Therefore, developing an environmentally friendly production process is of great concern to the chromic oxide industry. In this study, a new method for producing Cr2O3 without hexavalent chromium pollution was investigated. In this novel process, 97% of the total Cr—in the form of chromium sulfate (Cr2(SO4)3)—and Fe are leached from ferrochrome alloy using sulfuric acid. The concentration of Fe in the Cr2(SO4)3 solution can be reduced to 2 mg/L after precipitating with oxalic acid and extracting with di (2-ethylhexyl) phosphate. Cr2O3 is then produced by precipitating Cr from the Cr2(SO4)3 solution with sodium hydroxide, followed by calcination of the precipitated Cr(OH)3 at 500°C. Using this method, Cr2O3 with a purity of up to 99.3% was obtained in this study. Throughout the process, Cr existed only in the form of Cr(III); thus, the pollution caused by hexavalent Cr was eliminated, and environmentally friendly production of Cr2O3 was achieved.

The rates of corrosion of aluminum and hydrogen gas production in sodium hydroxide solutions without and with the additions of chromate, phosphate, and tungstate anions were examined. Potentiometri...

Magnesium oxide (MgO) nanoparticles have been widely used in a variety of applications because of their good surface reactivity. Magnesium oxide from bittern has a larger surface area compared to magnesium oxide from calcined magnesite and magnesium ions precipitation from bittern using sodium hydroxide has higher purity than using calcium hydroxide or ammonium hydroxide. In this research, sodium hydroxide was added to a bittern solution obtaining magnesium hydroxide precipitate, followed by the calcination process to produce magnesium oxide. Nano magnesium oxide was synthesized by the ultrasonic destruction process using ethanol and 2-propanol as media. In this study, sonication time and particle concentration effect on the ultrasonic destruction process were investigated. During the process, the sonication time was varied between 8, 16, 32, 64, and 128 minutes while the magnesium oxide concentration was varied between 1 %, 2 %, and 3 %. Increasing sonication time and particle concentration will decrease the particle size. The previous study shows that particles with very small sizes tend to have an agglomeration effect. The aim of this work is to optimize nano magnesium oxide production from bittern. Surfactant addition was also studied to prevent agglomeration between particles. Four types of surfactant namely anionic (sodium lauryl sulfate), cationic (cetyl tri-methyl-ammonium bromide), amphoteric (fatty acid amido alkyl betaine), and non-ionic (nonylphenol 10 ethoxylated) with a concentration of 1 % and a volume of 0.125 ml were added during the second ultrasonic destruction process. All types of surfactants have a positive effect to prevent agglomeration during the ultrasonic destruction process, with the amphoteric surfactant having the highest performance, Наночастицы оксида магния (MgO) широко используются в различных областях благодаря высокой поверхностной реакционной способности. Оксид магния из соляного раствора имеет большую площадь поверхности по сравнению с оксидом магния из кальцинированного магнезита, а осаждение ионов магния из соляного раствора с использованием гидроксида натрия имеет более высокую чистоту, чем при использовании гидроксида кальция или гидроксида аммония. В данном исследовании для получения оксида магния гидроксид натрия добавляли в соляной раствор для осаждения гидроксида магния с последующим прокаливанием. Нанооксид магния синтезировали методом ультразвуковой деструкции с использованием сред этанола и 2-пропанола. В данной работе было исследовано влияние времени ультразвуковой обработки и концентрации частиц на процесс ультразвуковой деструкции. Во время процесса время ультразвуковой обработки варьировалось в пределах 8, 16, 32, 64 и 128 минут, концентрация оксида магния – 1 %, 2 % и 3 %. Увеличение времени ультразвуковой обработки и концентрации частиц приводит к уменьшению размера частиц. Предыдущее исследование показало, что частицы очень малого размера имеют тенденцию к агломерации. Целью данной работы является оптимизация производства нанооксида магния из соляного раствора. Также изучали добавление поверхностно-активных веществ для предотвращения агломерации частиц. Во время второго процесса ультразвуковой деструкции добавляли четыре типа поверхностно-активных веществ: анионное (лаурилсульфат натрия), катионное (цетримониум бромид), амфотерное (амидоалкилбетаин жирных кислот) и неионное (этоксилированный нонилфенол 10) с концентрацией 1 % и объемом 0,125 мл. Все типы поверхностно-активных веществ оказывают положительное влияние на предотвращение агломерации в процессе ультразвуковой деструкции, причем амфотерное поверхностно-активное вещество обладает самой высокой эффективностью, Наночастки оксиду магнію (MgO) широко використовуються в різних областях завдяки високій поверхневій реакційній здатності. Оксид магнію з соляного розчину має більшу площу поверхні в порівнянні з оксидом магнію з кальцинованого магнезиту, а осадження іонів магнію з соляного розчину з використанням гідроксиду натрію має більш високу чистоту, ніж при використанні гідроксиду кальцію або гідроксиду амонію. У даному дослідженні для отримання оксиду магнію гідроксид натрію додавали в соляний розчин для осадження гідроксиду магнію з подальшим прожарюванням. Нанооксид магнію синтезували методом ультразвукової деструкції з використанням середовищ етанолу і 2-пропанолу. У даній роботі було досліджено вплив часу ультразвукової обробки і концентрації часток на процес ультразвукової деструкції. Під час процесу час ультразвукової обробки варіювався в межах 8, 16, 32, 64 і 128 хвилин, концентрація оксиду магнію – 1 %, 2 % і 3 %. Збільшення часу ультразвукової обробки і концентрації часток призводить до зменшення розміру часток. Попереднє дослідження показало, що частки дуже малого розміру мають тенденцію до агломерації. Метою даної роботи є оптимізація виробництва нанооксиду магнію з соляного розчину. Також вивчали додавання поверхнево-активних речовин для запобігання агломерації часток. Під час другого процесу ультразвукової деструкції додавали чотири типи поверхнево-активних речовин: аніонну (лаурилсульфат натрію), катіонну (цетримоніум бромід), амфотерну (амідоалкілбетаїн жирних кислот) і неіонну (етоксильований нонілфенол 10) з концентрацією 1 % і об'ємом 0,125 мл. Всі типи поверхнево-активних речовин чинять позитивний вплив на запобігання агломерації в процесі ультразвукової деструкції, причому амфотерна поверхнево-активна речовина володіє найвищою ефективністю

Natural diatomite modified by acetic acid (C-D) and sodium hydroxide (Na-D) for adsorbing manganese (Mn) was studied. The construction and morphology of the modified diatomite were then characterized by different efficient and accurate detection methods (Fourier transform infrared, scanning electron microscopy, and Brunauer-Emmett-Teller), and it was proved that C-D and Na-D increased the surface area and void volume compared to natural diatomite, and the modification of diatomite with acetic acid and alkali also significantly changed the structure of the functional groups of diatomite, especially in Na-D. Therefore, the adsorption rate of Mn by C-D and Na-D was higher than that of natural diatomite. The optimum conditions of Mn adsorption for C-D and Na-D were pH 5.0, 40 °C, 30 min and pH 5.0, 40 °C, 120 min, respectively, and this was best illustrated by pseudo-second-order kinetics. The Mn adsorption isotherm models showed that Mn adsorption on C-D and Na-D was stable, and the Langmuir adsorption isotherm model fitted adsorption processes of natural diatomite, C-D, and Na-D well as their correlation coefficients were 0.931, 0.940, and 0.991, respectively. These results suggested that modified diatomite with acetic acid and sodium hydroxide significantly increased the adsorption rate of Mn, which had an important application prospect for the remediation of Mn pollution in soil and water.

Functionalized ionic liquids (FILs) as extractants were employed for the separation of tungsten and molybdenum from a sulfate solution for the first time. The effects of initial pH, extractant concentration, metal concentrations in the feed were comprehensively investigated. The results showed that tricaprylmethylammonium bis(2,4,4-trimethylpentyl)phosphinate ([A336][Cyanex272]) could selectively extract W over Mo at an initial pH value of 5.5; the best separation factor βW/Mo of 25.61 was obtained for a solution with low metal concentrations (WO3: 2.49 g/L, Mo: 1.04 g/L). The [A336][Cyanex272] system performed effectively for solutions of different W/Mo molar ratios and different metal ion concentrations in the feed. The chemical reaction between [A336][Cyanex272] and W followed the ion association mechanism, which was further proved by the Fourier-transform infrared (FTIR) spectra of loaded [A336][Cyanex272] and the free extractant. The stripping experiments indicated that 95.48% W and 100.00% Mo were stripped using a 0.20 mol/L sodium hydroxide solution. Finally, the selective extractions of W and Mo from two synthetic solutions of different high metal concentrations were obtained; the separation factor βW/Mo reached 23.24 and 17.59 for the first and second solutions, respectively. The results suggest the feasibility of [A336][Cyanex272] as an extractant for the separation of tungsten and molybdenum.

A rigid abright drill provided the ratory motion for a brass disc employed as the tool having no embeded abrasive material, Sodium Chloride and Sodium Hydroxide having different concentrating rates between (10% - 50%) were employed as electrolytes covering the gab between the tool and workpieces. Mild steel, free machining -rass and pure aluminum in the as-received conditions were employed as workpieces. Material removal rates were found to be greater for smaller gap widths, higher speed of revolution, greater gap voltage, higher percentages of electrolyte conceration and greater electrolyte velocity for all workpiece materials especially when using sodium chloride. As the material removal rate increases, consequently workpiece surface temperature rises. Such temperature rises all-over the entire range did not exceed + 30°C. Workpiece surface finish were found to improve for higher rates of material removal for mild steel and free machining brass only. No such improvements were noted after aluminum machining except at high tool speeds. Deep scatered scratchs in aluminum specimens were noted at lower tool speeds.

Chemical energy storage and use is a critical part of a sustainable world. In this laboratory experiment, students construct and use an inexpensive hydrogen fuel cell to power a calculator or a clock. The reusable cells are prepared from plastic syringes and a nickel mesh that is coated with a palladium metal catalyst by electroless deposition. One syringe is filled with hydrogen gas and the other with air. A sodium hydroxide solution is the bridge between the cells. Students measure the produced voltage and combine two fuel cells to power electronics requiring 1.5 V. The goal is for students to make the connection between theory and practice for symbolic representations of redox reactions and their macroscopic and atomic/molecular interpretations.

The process of hydrogen formation and the associated risk of combustion and explosion is a complex problem concerned with the hydrogen and radiation safety of nuclear reactors. Lithium, potassium and sodium hydroxides are used in VVER reactors as corrective additives for keeping the hydrogen potential of the water coolant with boric acid at a controlled level of 5.8 to 10.3. In the process of investigating the interaction of aqueous solutions of the above hydroxides with aluminum, the most chemically active of these is lithium hydroxide; this reaction proceeds with hydrogen formed at a high rate at room temperature (in an exothermic mode). The processes of hydrogen generation in hydroheterogeneous compositions with potassium and sodium hydroxides proceed at an acceptable rate with heating to ~ 60 °C. The kinetics of hydrogen generation depends in a complex way on the content of boric acid, namely, the hydrogen yield is at a level of ~ 1000 ml at a low concentration of 0.01 to 0.05 g/l, and there is no hydrogen formation at a concentration of 0.6 g/l. According to the coolant quality standards, in the hot state of a VVER-1000 unit or in the reactor state at the minimum controlled power level, the total concentration of alkali metals is about 1 mg/dm3, i.e. two to three orders of magnitude as less as in the investigated compositions. The discovery of the influence of alkali metal hydroxides on the formation of hydrogen with the participation of structural materials based on the example of aluminum makes it possible to suggest that the hydroxides of these metals contained in the coolant in a small amount can also take part in the hydroheterogeneous process of formation of minor hydrogen amounts. The potential for hydrogen formation in such a way needs to be taken into account during long-term operation of nuclear reactors, and during accidents and incidents at NPPs

Thermally-induced reaction between liquid sodium (Na(l)) and calcium hydroxide (Ca(OH)2(s)) was investigated as one of the possible component reactions when Na(l) was reacted with concrete materials under a postulated severe accidental condition in a sodium-cooled fast reactor. The Na(l)–Ca(OH)2(s) reaction was traced using a differential scanning calorimetry (DSC), placed in an argon substituted glove box. An exothermic DSC peak appeared in the temperature range of 550–700 K was attributed to the Na(l)–Ca(OH)2(s) reaction to form a mixed phase comprised of calcium oxide (CaO(s)), sodium hydroxide (NaOH(s,l)) and sodium oxide (Na2O(s)). Based on morphological analyses of reacting system, a physico-geometrical reaction model was proposed: the reaction initiates at the initial contact area of Na(l) and Ca(OH)2(s) and proceeds by the movement of the reaction interface toward Ca(OH)2(s), where the product layer is composed of CaO(s), NaOH(s,l), and Na2O(s). Therefore, the Na(l) diffusion through the product layer is the necessary process to promote the reaction between Na(l) and Ca(OH)2(s), for which a significant influence of the melting of NaOH(s) that has on the overall kinetic behavior is expected. This melting occurs midway through the Na(l)–Ca(OH)2(s) reaction at 594 K. The overall Na(l)–Ca(OH)2(s) reaction was analyzed kinetically using the DSC curves recorded at different heating rates. A partially overlapping two-step reaction feature was evidenced, in which the primary and secondary reaction steps were characterized by the apparent activation energy values of 128 and 138 kJ mol−1, respectively. The multistep feature of the Na(l)–Ca(OH)2(s) reaction could result from the melting of NaOH(s) in the product layer.

The selective separation of arsenic in the NaOH-S system from arsenic dust containing Pb, Sb, and Zn was studied by central composite design response surface method in this investigation. The results indicated that the presence of elemental sulfur can prevent lead and antimony leaching from arsenic dust effectively. The optimal leaching conditions were established as follows: 3.0 mol/L sodium hydroxide, 10 g/L sulfur, leaching temperature 95 °C, leaching time 2.0 h, liquid to solid ratio 6, and stirring speed 400 r/min. The arsenic leaching efficiency can reach 99.37% under the optimized conditions, meanwhile 98.39% of Sb, 99.74% of Zn, and 99.91% of Pb remained in the leach residue with the arsenic content < 0.1%. Oxidation-cooling crystallization has been used to recover sodium arsenate from the leaching solution under the optimal reaction conditions: C(H2O2)/C(As) 0.45, oxidation temperature 50 °C, stirring speed 200 r/min, crystallization temperature 30 °C, and crystallization time 120 min. This work presents a novel route for selective separation of arsenic and potential recycling lead and antimony from the arsenic dust in the NaOH leaching system with adding elemental sulfur.

Peat is an exceptionally problematic soil for construction purposes and is often stabilized by traditional stabilizers (like cement), which emits 0.95-ton carbon dioxide (CO2) per ton of cement during their production. Alkali-activated ground granulated blast furnace slag (GGBS) with its low carbon dioxide (approximately 0.07-ton CO2) emissions and higher strength gain provides a promising substitute to traditional stabilizers. Therefore, this study presents the viability of alkali-activated GGBS-stabilized Indian peat. The three types of peats (sapric, fibric, and hemic) were collected to cover a wide range of variations of fibre (6–73%) and organic content (21–79%). The sodium hydroxide (NaOH) molarities (M) of 6, 9, 12, and 15 were used to activate specimens, with GGBS percentages of 10, 20, and 30% by weight of dry peat and alkali/binder ratios of 0.5, 0.7, and 0.9. The test results show that the UCS of peat-GGBS depends on the molarity of NaOH, A/B, electrical conductivity (EC), pH, curing period, and organic content of the peat-GGBS matrix. The optimum combination for the peat-GGBS blend is 20% GGBS, NaOH molarity of 9, and A/B ratio of 0.7. Furthermore, it was found that UCS increases with the curing period and decreases with organic content (OC). The formation of aluminium silicate, sodium aluminosilicate, and potassium aluminosilicate responsible for strength gain is confirmed by XRD. The FESEM micrographs reveal that these products result in the filling of pore spaces to form a smooth and dense soil-binder matrix.

Hydrogen is considered an attractive alternative to fossil fuels, but only a small amount of it is produced from renewable energy, making it not such a clean energy carrier after all. Producing hydrogen through water electrolysis is promising, but using a cost-effective and high-performing catalyst that has long-term stability is still a challenge. This study exploits, for the first time, the potential of zinc oxide nanoparticles with diverse morphologies as catalysts for the electrocatalytic production of hydrogen from water. The morphology of the nanoparticles (wires, cuboids, spheres) was easily regulated by changing the concentration of sodium hydroxide, used as the shape controlling agent, during the synthesis. The spherical morphology exhibited the highest electrocatalytic activity at the lowest potential voltage. These spherical nanoparticles had the highest number of oxygen vacancies and lowest particle size compared to the other two morphologies, features directly linked to high catalytic activity. However, the nanowires were much more stable with repeated scans. Density-functional theory showed that the presence of oxygen vacancies in all three morphologies led to diminished band gaps, which is of catalytic interest.

Triangular and hexagonal copper nanoplates were synthesized by reduction of copper(II) nitrate with hydrazine hydrate in water in the presence of 2-[2-(2-methoxyethoxy)ethoxy]acetic acid. The resultant copper particles were characterized by X-ray diffraction analysis and electron microscopy. The effect of the synthesis temperature and duration, as well as of the stabilizer, copper ions, and sodium hydroxide concentrations on the size, morphology, and polydispersity degree of the particles synthesized was evaluated.

Recently, the use of polymers in agricultural and horticultural applications has been seen as a solution to reduce water consumption and excess fertilizer use in particularly. In this study, macrogels were synthesized to allow fertilizer species and water to be controlled and released in the soil. A natural macrogel derived from N,N-Dimethylacrylamide (DMAAm), Maleic Acid (MA) and Citric Acid (CA) was selected because of its ability to absorb/release a large amount of water and to have modifiable functional groups. Urea, which is an abundant source of nitrogen, was chosen to model the fertilizer. The macrogel was prepared using easily available, low-cost, modifiable starting materials by redox polymerization technique. p(DMAAm-co-MA-co-CA) (DMC1) surface was modified by hydrochloric acid (HCl) and sodium hydroxide (NaOH) to obtain p(DMAAm-co-MA-co-CA)/HCl (DMC2) and p(DMAAm-co-MA-co-CA)/NaOH (DMC3), which have positively and negatively charged, respectively. After being analyzed for intermolecular interactions (Fourier-Transform Infrared Spectroscopy,FT-IR) and thermal properties (Thermogravimetric Analysis,TGA), the macrogels were tested in terms of sorption isotherms and thermodynamic parameters. However, in order to examine the urea release mechanism, the macrogels were tested using four release models such as Zero Order Kinetic Model(Z-O), First Order Kinetic Model(F-O), Higuchi(H) and the Korsmeyer-Peppas(K-P) power law. Cumulative urea release values for DMC1, DMC2 and DMC3 macrogels were calculated as 100% at pH 4 and 10, 100% at pH 6, 8 and 10, 100% at pH 4, 6, 8 and 10, respectively. Analyzes confirmed that synthesized macrogels can be good water holder for soil and can be a slow release of urea.