Alum Research Articles

A 36-nucleus silver-thiolate cluster encapsulating double sulfates and co-protected by cyclen

New type of cyclic multi-dentate ligand named, Cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN4), was successfully introduced onto the surface of a 36-nucleus double sulfates templated silver-thiolate cluster [(SO4)2@Ag36(SPhtBu)24(cyclen)4(CF3CO2)6(OH)2] (1). The nanocluster was investigated and characterized by single-crystal X-ray crystallography (SXRD), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), ultraviolet−visible (UV) spectroscopy, and photoluminescence (PL). The cluster shows very good solution stability in four different solvents and excellent thermal stability in the solid-state. It shows orange-red emission in EtOAc/THF/CH2Cl2/CHCl3 at 77 K. The lifetime of 1 in four different solvents is over 140 μs, and the highest quantum yield of 1 is 25.46 %. The nanocluster shows temperature-dependent photoluminescence properties in different solvents, which make them potential candidates in the fields of optical devices for future applications.

Effect of different initiators on the properties of diacetone acrylamide grafted starch-based adhesive

Environmentally friendly and non-toxic bio-based adhesives are emerging as the most promising substitutes for petroleum-based adhesives, attracting increasing attention. This work involved the synthesis of a starch-based adhesive for particleboards by grafting diacetone acrylamide (DAAM) onto starch. The graft polymerization was initiated using three different initiators: ammonium persulfate (APS), hydrogen peroxide (H2O2)/ammonium ferrous sulfate system, and ceric ammonium nitrate (CAN). A comparative study was conducted to assess the varying effects of these initiators. The results showed that in the graft copolymerization of starch with DAAM, different initiators produced different types of free radicals, and CAN initiation produced alkyl radicals and long-chain alkyl radicals with a peak total spin value of 3.96 × 1015, and thus had the highest grafting efficiency and grafting rate of 72.59 % and 16.75 %, respectively. From the comparison of the total number of spins, it can be seen that CAN is more targeted for starch initiation. In addition, characterization results from Fourier transform infrared spectroscopy and confocal Raman spectroscopy showed that DAAM underwent a graft copolymerization reaction with starch. Notably, the adhesive initiated by CAN demonstrated the highest water resistance and mechanical strength, with an absorption thickness expansion and static bending strength of 8.52 % and 10.56 MPa, respectively.

Leaching a complex copper–cobalt oxide ore from Zebesha Mine in Zambia, a novel method

The study focused on leaching complex copper–cobalt oxide ore from Zebesha Mine in Zambia. The chemical analysis indicated the presence of cobalt, copper, nickel, manganese and iron as base metals. Copper is predominantly found in malachite and a small portion in heterogenite mineral along with cobalt, iron, manganese and nickel. The leaching process involved using solutions containing iron: ferrous sulphate, FeSO4·7H2O; ferrous ammonium sulphate, (NH4)2Fe(SO4)2·6H2O; and ferric sulphate, Fe2(SO4)3. The effects of temperature and salt concentrations were studied alongside metal content determination through titration-atomic absorption spectroscopy techniques. It was observed that the preferential dissolution of copper occurred with Fe2 (SO4)3 while temperatures above 70°C leaching with FeSO4·7H2O resulted in the recovery of over 80% of manganese and cobalt. This study suggests that ferrous containing lixiviants can effectively promote the manganese and cobalt dissolution but are not efficient for extracting copper. Furthermore, using Fe2(SO4)3 may allow for selective leaching of copper.

Continuous flow-through electro-Fenton membrane reactor with Fe−N4-doped carbon membrane as cathode for efficient removal of dimethylacetamide

Fe − N4-doped conductive carbon membranes (FeCMs) were fabricated through high-temperature carbonization using chitosan and phenolic resin as the raw materials and ammonium ferrous sulfate (NH4Fe(SO4)2) as the dopant. The impact of the NH4Fe(SO4)2 doping rate (0 − 15 wt%) on the structure and performance of the FeCM was investigated. Moreover, a continuous flow-through electro-Fenton membrane reactor (EFMR) was constructed using an FeCM cathode and a Ti plate anode for the efficient removal of dimethylacetamide (DMAC). The resultant carbon membrane with 10 wt% NH4Fe(SO4)2 (M10) exhibited a smaller pore size (40.1 nm), a higher porosity (48.3 %), a larger specific surface area (531.6 m2/g), and a higher mechanical strength (6.7 M Pa) than the other membranes. The removal rate of DMAC by EFMR with M10 as the cathode at 2 V reached 42.1 %, which was much greater than that without NH4Fe(SO4)2 (3.6 %). The electrosynthesis ·OH concentration by EFMR with M10 as the cathode was approximately 89.1 mg/L, which was much greater than that of most carbon-based materials. The intermediates of DMAC degradation (such as N-methylacetamide, acetamide, acetaldehyde, and acetic acid) were determined by gas chromatography–mass spectrometry (GC–MS), and the removal of total organic carbon (TOC) was approximately 3.4 %. Density functional theory (DFT) calculations revealed that the Fe atom served as the active site for dissolved oxygen adsorption and electrogeneration of ·OH. After 5 days of continuous EFMR operation, the DMAC removal rate remained at 88.8 % of the initial value (42.1 %). This study presents a novel approach for designing and fabricating conductive carbon membranes to improve industrial wastewater treatment performance.

Tuning Iron Active Sites of FeOOH via Al3+ and Heteroatom Doping-Induced Asymmetric Oxygen Vacancy Electronic Structure for Efficient Alkaline Water Splitting.

Oxygen evolution reaction is the essential anodic reaction for water splitting. Designing tunable electronic structures to overcome its slow kinetics is an effective strategy. Herein, the molecular ammonium iron sulfate dodecahydrate is employed as the precursor to synthesize the C, N, S triatomic co-doped Fe(Al)OOH on Ni foam (C,N,S-Fe(Al)OOH-NF) with asymmetric electronic structure. Both in situ oxygen vacancies and their special electronic configuration enable the electron transfer between the d-p orbitals and get the increase of OER activity. Density functional theory calculation further indicates the effect of electronic structure on catalytic activity and stability at the oxygen vacancies. In alkaline solution, the catalyst C,N,S-Fe(Al)OOH-NF shows good catalytic activity and stability for water splitting. For OER, the overpotential of 10 mAcm-2 is 264mV, the tafel slope is 46.4 mVdec-1, the HER overpotential of 10 mAcm-2 is 188mV, the tafel slope is 59.3 mVdec-1. The stability of the catalyst can maintain ≈100h. This work has extraordinary implications for understanding the mechanistic relationship between electronic structure and catalytic activity for designing friendly metal (oxy)hydroxide catalysts.

Synergetic recycling of permanent magnet and Li-ion battery cathode material for metals recovery

Rare earth elements (REEs)-based (NdFeB) magnets and lithium−ion batteries (LIBs) are critical for a low−carbon economy. Their production depends on critical elements like REEs, Li, Co and Ni. Recycling of these products have been explored separately as a potential solution. Conventional methods for recycling NdFeB magnets and LIBs face challenges like high energy consumption, lengthy processing, excessive reagent usage, and waste generation. In this study, a novel synergetic recycling methodology is proposed to minimize these challenges. The idea is based on using waste ferrous sulfate solution generated during magnet leaching as a reducing and leaching reagent for battery recycling thereby eliminating the need for additional reagents for oxidation of iron in NdFeB and reduction of cathode material in LIBs. The magnet is leached in diluted H2SO4 at 70 °C followed by double sulfate precipitation for REEs with Na2SO4. The REE-depleted but acidic ferrous solution is then used for reductive leaching of cathode material at 90 °C. The overall recovery rates of REEs, Li, Co, Ni, and Mn in this process are >95%. The iron from magnet material is recovered as crystalline and easily-filterable iron compound that can be converted to goethite and used as a byproduct. This synergetic approach not only reduces reagent consumption and waste generation aligning with the principles of circular economy but also offers improved efficiency, resource conservation, and environmental sustainability.

Performance of V–Fe based catalysts on the oxidation of dibenzothiophenes

To obtain fossil fuels with ultra-low S levels at friendly conditions, different V oxides formulations on alumina modified with Fe were characterized and selected to oxidize dibenzothiophene (DBT), 4-methyl DBT and 4,6-dimethyl DBT prevailing in diesel fuel. V–Fe based catalysts (5 or 10 wt% of V) were obtained by impregnation of ammonium metavanadate solutions on Fe-modified alumina, obtained by impregnation of Mohr salt on pseudoboehmite (2 wt% of Fe). The catalysts were calcined in air atmosphere, and after were partially reduced with H2 flux to obtain a mix of several oxidation states of V and Fe species, to evaluate the interaction of Fe in VOx/Al2O3 catalysts and determine its effect on the oxidation processes. The structural and optical properties, as well as surface species, were determined by SEM-EDS, TPR, XRD, Raman, ATR-FTIR, photoluminescence, UV–Vis diffuse reflectance, and XPS spectroscopy. The catalytic performance was evaluated in oxidative desulfurization (ODS) and photocatalytic ODS (PODS) processes. The experimental results showed the addition of Fe promoted the catalytic activity of both ODS and PODS reactions. ODS activities of V–Fe catalysts increase up to 7.5 times with respect to V catalysts without Fe, and the most active catalyst (V5Fer) presents a characteristic oxidation time of 50 min for 4,6-DMDBT. The PODS activity of V10Fec was like ODS activity, showing it is possible to oxidize the dibenzothiophenes under friendly conditions to obtain lower S levels. The promoting effect of Fe was due to the interaction of Fe2+ and Fe3+ with the catalytic support, favoring the distribution of surface V3+ and V4+ species. Additionally, Fe improved the optical properties of the catalysts since the bandgap energy decrease and low recombination rate of the electron-hole pair were observed. Therefore, V–Fe based catalysts are photocatalytically actives to be used in PODS processes.

A method to improve sensitivity of Ferrous ammonium sulfate - Benzoic acid - Xylenol orange (FBX) aqueous radiation dosimeter

Ferrous ammonium sulfate - Benzoic acid - Xylenol orange (FBX) solution is known for its dosimetry properties in the dose range applicable in radiation oncology. Several attempts at improving its dose sensitivity have been reported in literature. The current work explores a novel method to improve the dose response of the system in the range 0–10 Gy with the original standard composition of the solution. Value of the sensitivity of the dosimeter was found to be 7.471/Gy with excellent linearity using the developed method. This is 115 times higher than the sensitivity obtained using the conventional methods.

Reaction Mechanism in Standardized α-Cellulose Content Test: Study from Boehmeria nivea Fiber

In defense industry, α-cellulose is the main component of nitrocellulose propellant. However, a detailed description of the reaction mechanism of each treatment step in SNI 0444-2009 is still very scarce. This study addresses this gap by presenting the reaction mechanisms of each treatment and the symbols used in the SNI 0444-2009 procedure. The separation of lignin from α-cellulose occurred by breaking the C‒O bond linking them. This bond was broken by the ‒OH group of NaOH via a hydrolysis reaction. The reaction was initiated with the elimination of a hydrogen atom from the lignin structure by the hydroxyl ion (‒OH), and the C‒O bond was broken by a hydrolysis reaction. The breaking of this bond was indicated by the disappearance of the IR peaks at wavenumbers 1049 and 1190 cm–1 in the filtrate after extraction. The SNI 0444-2009 method for the α-cellulose content test was carried out by a redox back titration of Cr(VI) with Fe(II) from ferrous ammonium sulfate. This titration was conducted to calculate the amount of Cr(VI) ions in potassium dichromate or Cr(VI) that did not react with lignin or beta cellulose in the filtrate. Understanding the contribution and reaction mechanisms of each compound involved in the SNI 0444-2009 procedure contributed to obtaining accurate data on α-cellulose content. In this study, the calculated α-cellulose content of the flax fiber was 96.75%. Furthermore, the detailed mechanism of the redox reaction was discussed in detail in this paper.

Influence of Retanning Agents on Physical Characteristics of Snow-White Glove Leather from Goat Skin

The quality of leather is subject to various elements, such as the specific raw material used, and the processing techniques implemented throughout the production process. Goatskin, renowned for its exceptional softness and durability, is frequently employed in the production of gloves owing to its desired attributes, notably its capacity to produce snow-white gloves. Retanning is an essential step in the leather manufacturing process as it significantly improves the characteristics of the leather. Through an investigation into the impacts of distinct retanning agents on goatskin leather gloves, this research endeavor seeks to offer significant knowledge regarding the most effective retanning procedures that can augment the tactile attributes of snow- white leather gloves. In this study, formaldehyde, alum, chromium, and chromium alum were employed as retanning agents. The retanned leathers were assessed by physical parameters, Principal Component Analysis (PCA), and Fourier Transform Infrared spectroscopy (FTIR), then compared to a commercially available snow-white leather glove. The physical characteristics of chrome alum retanned leather showed a high degree of softness (6.60±0.02 mm), good tear strength (1.530±117 N/cm), and tensile strength (1.500±100 N/cm 2 ). The principal component analysis (PCA) also supported that the properties of chrome alum retanned snow-white glove leather closely resemble commercial leather and the result from this study suggested that all factors notably impact the skin's physical quality, except for thickness. Additionally, the FTIR analysis reveals similar functional groups from the different retanned leathers indicated by comparable peaks and stretching patterns. Therefore, chrome-alum could be a well alternative retanning agent for the production of snow-white glove leather.

12C6+ Irradiation Mutation for the Selection and Breeding of High-Cholesterol-Lowering Lactobacillus

A high-throughput screening method for the selection of lactic acid bacteria with high cholesterol-degrading ability was established using the 12C6+ beam irradiation mutagenesis technique. This study aimed to breed excellent strains with high cholesterol-degrading capability and explore the mechanisms of cholesterol degradation by these strains. The mutated strains JMR-01 (Lactobacillus reuteri) and SN-2 (Lactobacillus rhamnosus) after irradiation were primarily screened for high cholesterol-degrading strains by optimizing the KENJI culture medium with colony diameter as an indicator. The primary screened strains were further screened using ammonium ferric sulfate method. The mechanisms of cholesterol degradation by lactic acid bacteria were further investigated by determining the total cholesterol degradation rate, the cholesterol degradation rate through co-precipitation and absorption. The results showed that after primary and secondary screening, four mutant strains with high cholesterol-degrading ability (JMR-01-1, JMR-01-2, SN-2-1, SN-2-9) were selected. The cholesterol-degrading ability of strain JMR-01-1 was increased by 9.7% compared to the original strain JMR-01 (P<0.05), and the cholesterol-degrading ability of strain SN-2-1 was increased by 11.5% compared to the original strain SN-2. The total cholesterol degradation rate, co-precipitation, and absorption of cholesterol degradation rate of the four mutant strains showed no significant difference in the co-precipitation effect on cholesterol compared to the original strains, but the relative absorption rate was significantly increased. This study optimized the screening method for cholesterol-degrading strains and demonstrated through the exploration of different cholesterol degradation pathways by lactic acid bacteria that this screening method can select strains with high cholesterol absorption capacity.

EVALUATION OF ORGANOLEPTIC &IN-VITRO BIOAVAILABILITY PROPERTIES OF IRON FORTIFIED YOGURT

Yogurt is a fermented dairy product formed by the action of Lactobacillus spp. with the help of lactic acid fermentation procedure.In India major cause of anaemia is dietary iron deficiency.Iron deficiency causes poor cognitive performance, behavioural abnormalities, poor physical growth of children, disturbed immune function, lack of physical activity and poor work performance in all age groups. Worldwide dairy foods are most popular nutritious product so dairy foods may be used as a vehicle of food fortification. The iron compound which are used as a food fortificant should contain highly bioavailable iron and the physical chemical characteristics of the fortified food product should be similar to non-fortified product. In the present study yogurt was fortified with ammonium ferrous sulphate, ferrous sulphate, iron-casein complex in three different concentrations (20mg, 30mg, 40 mg iron) /kg milk sample. Sensory evaluation and In-vitro bioavailability study of yogurt samples were analyzed at 1st, 4th, 7th day of storage. Statistical analysis of the study shows ferrous sulphate and iron-casein complex fortified yogurt enhances the iron absorption compared to ammonium ferrous sulphate fortified yogurt.

Mechanistic study of the acidic aqueous solution of chrome alum chemical dosimeter: Steady state, pulse radiolysis and conductivity studies

It is crucial to have an efficient and reliable approach to ensure an optimum traceability in high dose range and high dose rate dosimetry for radiation processing (food irradiation, surgery devices sterilization …). Chemical solution dosimeters are well suited for this purpose. By using γ-irradiation and pulse radiolysis, we evaluated the performances of the chrome alum KCr(SO4)2·12H2O based on the radiation induced oxidation of Cr3+ to Cr6+ in N2O-saturated aqueous solutions buffered at pH 4 by the hydroxyl radical (•OH). With combination of spectrophotometric and conductometric measurements, a mechanism has been put forward to elucidate the oxidation of Cr3+ leading to Cr6+. The suggested mechanism involves an initial adduct formation, [Cr3+ – •OH], that enables inner-sphere electron transfer. As far as dosimetry is concerned, this study showed that the absorbance at 350 nm of the radiation induced Cr6+ increases linearly with the dose with a yield of G (Cr6+) = 0.128 μmol J−1. No dose rate effect was observed up to 80 kGy min−1. This aqueous solution could be used for chemical dosimetry, mainly in the high dose range (up to 5 kGy) and high dose rate (up to 80 kGy min−1). The main advantage of using this aqueous solution is its equivalence to human tissue in terms of radiation absorption properties.

Synthesis of gamma irradiated acrylic acid-grafted-sawdust (SD-g-AAc) for trivalent chromium adsorption from aqueous solution

Water pollution caused by chromium released from tannery is a serious concern to the environment and public health. Chromium removal from tannery effluent is a crying need before discharging to the surface water. In this study, acrylic acid-grafted sawdust was prepared by Tectona grandis sawdust grafting with acrylic acid employing gamma irradiation in the presence of air and Mohr's salt. It was treated with NaOH and the characterization of surface morphology and functional groups of modified sawdust was studied by SEM and FTIR.. The effects of solution pH, adsorbent dosage, adsorption time, and initial Cr(III) ion concentration were investigated by batch sorption studies. The process was found to be pH, temperature and concentration dependent. Langmuir and Freundlich isotherms were applied to realize the adsorption process in depth, and it was found that the Langmuir isotherm model fitted well with experimental data (R2 value of 0.983). The maximum monolayer adsorption capacity of acrylic acid-grafted sawdust for Cr(III) from aquous solution was found to be 21.55 mg g-1 at 25 °C. Pseudo-first-order and pseudo-second-order kinetic models were employed to analyze the kinetics of the process, and it was found that the experimental process followed the pseudo-second-order kinetic model, i.e. chemisorption. This study revealed that acrylic acid-grafted sawdust has a decent potential for the removal of Cr(III) from tannery effluents.

Self-supported iron-doped nickel oxide multifunctional electrodes for highly efficient energy storage and overall water-splitting uses

Caused by complex synthesis processes, slow diffusion rates, and the formation of undesired nanostructures, it is tedious to produce a high-quality nickel oxide (NiO) electrodes for potential energy storage and water splitting applications. This paper introduces a novel chemical technique for producing self-supported iron-doped NiO electrodes having a high concentration of oxygen vacancies by utilizing different iron-based salts i.e. iron nitrate, iron chloride, iron ammonium sulfate, iron fumarate, and iron sulfate salts. After examining physical properties, the electrochemical energy storage and water splitting measurements were performed where iron nitrate precursor-mediated self-supporting Fe-NiO electrode confirms the optimum performance. Specifically, it exhibits a specific capacitance (SC) of 3302.5 Fg−1 at a current density of 5 Ag−1. The as-fabricated Fe-NiO-A//Bi2O3 asymmetric supercapacitor has a broad voltage range of 1.5 V, a remarkable volumetric-energy-density of 98.2 W hkg−1 at a power density of 900 Wkg−1, and a long-lasting cycling life with 92.6 % capacity retention after 5000 cycles at a current density of 15 Ag−1. A bifunctional Fe-NiO//Fe-NiO electrocatalyst demonstrates a current density of 10 mA cm−2 and remarkable long-term durability of 75 h without any degradation while operating at an ultra-low cell voltage of only 1.51 V, specifying importance of self-supported Fe-doped NiO electrodes for electrochemical energy storage and water splitting applications.

Multistage hydrometallurgical process for enhanced recovery and individual separation of Nd and Pr from NdFeB magnet scrap

This study introduces a multistage hydrometallurgical process designed for the recovery and individual separation of Nd and Pr from NdFeB magnet scrap. Following demagnetization, the magnet underwent crushing, grinding, and leaching using a sulfuric acid solution. The pH of the resultant leachate was subsequently adjusted to 1.2 using a NaOH solution, leading to the precipitation of Nd and Pr as sodium double sulfates. The produced double sulfate was then mixed with a saturated NaOH solution, resulting in the formation of rare earth hydroxide. The hydroxide was further decomposed into oxides (REO) after calcination at 500°C. The REO was dissolved in hydrochloric acid and nitric acid solutions to investigate the individual separation of Nd and Pr using the D2EHPA–TOA extractant system and compare the results with D2EHPA-only system. It was concluded that the extraction mechanism of D2EHPA–TOA system is highly dependent on the acidity of the solution, with TOA having a synergistic effect on the REE extraction when pH > 3, and an antagonistic effect when pH ≤ 3. In terms of extraction efficiency, both extractant systems demonstrated efficiency levels exceeding 99% when the pH was ≥2, with similar behavior when extraction was performed in HCl and HNO3 media. Although both extractant systems yielded unsatisfactory outcomes in the separation of Nd and Pr, a marginal improvement was observed with the incorporation of TOA into the extractant system. This observation implies the potential of exploring analogous combinations in future studies.

An improved method for measuring catalase activity in biological samples.

Catalase (CAT) is an important enzyme that protects biomolecules against oxidative damage by breaking down hydrogen peroxide (H2O2) into water and oxygen. CAT is present in all aerobic microbes, animals, and plants. It is, however, absent from normal human urine but can be detected in pathological urine. CAT testing can thus help to detect such urine. This study presents a novel spectrophotometric method for determining CAT activity characterized by its simplicity, sensitivity, specificity, and rapidity. The method involves incubating enzyme-containing samples with a carefully chosen concentration of H2O2 for a specified incubation period. Subsequently, a solution containing ferrous ammonium sulfate (FAS) and sulfosalicylic acid (SSA) is added to terminate the enzyme activity. A distinctive maroon-colored ferrisulfosalicylate complex is formed. The formation of this complex is a direct result of the reaction between FAS and any residual peroxide present. This leads to the generation of ferric ions when coordinated with SSA. The complex has a maximum absorbance of 490 nm. This advanced method eliminates the need for concentrated acids to stop CAT activity, making it safer and easier to handle. A comparative analysis against the standard ferrithiocyanate method showed a correlation coefficient of 0.99, demonstrating the new method's comparable effectiveness and reliability. In conclusion, a simple and reliable protocol for assessing CAT activity, which utilizes a cuvette or microplate, has been demonstrated in this study. This interference-free protocol can easily be used in research and clinical analysis with considerable accuracy and precision.

Carbon Emission Characteristics and Influencing Factors of Typical Processes in Drinking Water Treatment Plant

Based on the actual operating conditions and data monitoring, the carbon emission characteristics of typical processes of a drinking water treatment plant (DWTP) in Tianjin were studied. The total carbon emission intensity measured by CO2-eq was 0.254 kg·m-3, and the proportion of carbon emissions from electricity consumption and reagent consumption was 81.76% and 9.15%, respectively. The key carbon emission sectors of electricity consumption were the water supply pump house, ultrafiltration membrane process, and inlet pump house, which accounted for 50.99%-73.51%, 17.64%-20.70%, and 17.97%-22.40% of the total carbon emission from electricity consumption in the DWTP, respectively. The contribution of sodium hypochlorite to the carbon emission of reagent consumption was 89.12%-90.30%, followed by ferric chloride, PAC, and ammonium sulfate. In the traditional water purification process, the carbon emission intensity of the process unit was in the order of inlet pump house > rapid filter > sedimentation tank. The order in the ultrafiltration membrane advanced treatment process was inlet pump house > ultrafiltration membrane > mechanical coagulation > clarification tank. The carbon emission intensity of the rapid filter process and the ultrafiltration membrane process were 0.070 9 kg·m-3 and 0.109 0 kg·m-3, respectively. The ultrafiltration membrane process could save 23% of the reagent consumption, and its carbon emission of electricity consumption was twice that of the traditional treatment process. The analysis of factors affecting carbon emission in key sectors showed that the raw water quality parameters such as turbidity, pH, ammonia nitrogen, temperature, etc., were significantly correlated with the carbon emission intensity of sodium hypochlorite. There was a significant linear regression relationship between ex-factory water pressure, daily water supply, and carbon emission intensity of the water supply pump house. The control measures of water quality and water pressure can effectively reduce the carbon emissions of the DWTP.

Design and Practice of Analytical Chemistry Experimental Teaching Based on BOPPPS Model—Taking “Determination of Fe(II) Content in Ammonium Ferrous Sulfate” as an Example

Design and Practice of Analytical Chemistry Experimental Teaching Based on BOPPPS Model—Taking “Determination of Fe(II) Content in Ammonium Ferrous Sulfate” as an Example

Комплексная переработка золотосодержащего сырья с использованием смеси гидродифторида и сульфата аммония

The possibility of processing tungsten- and aurum-containing raw materials using a mixture of NH4HF2 and (NH4)2SO4 has been studied. It has been established that when heated with the indicated reagents to 200°C, fluorination of the components included in the mineral raw material occurs with the formation of simple and complex fluorides; a further increase in temperature is accompanied by the formation of ammonium hydrosulfate NH4HSO4, which leads to the conversion of fluorides into double sulfates. The influence of the content of NH4HF2 in the reaction mixture on the degree of processing mineral raw materials was shown. The ways of extracting components of mineral raw materials with obtaining commercially demanded compounds as commercial products are demonstrated.