Concentrated Sulfuric Acid Research Articles

Environmentally safe technology of waste processing of galvanic production

It is known that waste is difficult to purify using existing reagent methods to the standards of the MPC. In addition, the formed sediments contain poorly soluble hydroxy compounds of heavy metals and gypsum, which makes it impossible to dispose of iron- and copper-containing electroplating sludges. The purpose of the study was to study the possibility of ion exchange separate and simultaneous extraction of iron and copper ions from acidic solutions of pickling and copper plating in galvanic production to obtain ferrites. In the course of research, the highly acidic cation exchange resin Dowex HCR S/S in the H+ form was chosen as the cationite. The choice of a strongly acidic cationite is justified, based on the fact that cationites of this type are able to easily lose hydrogen ions due to their displacement from the cationite matrix by other cations of the solution. The sorption processes of iron (II) and copper (II) ions were carried out under dynamic conditions. In the course of experimental studies, it was shown that with an increase in the concentration of sulfuric acid, the full exchangeable dynamic capacity of the cationite significantly decreases both during the sorption of iron ions and during the sorption of copper ions. For iron-containing solutions, full dynamic exchange capacity decreases from 1.39 g-eq/dm3 in the absence of H2SO4 in the initial solution and decreases to 0.3-0.46 g-eq/dm3 at a concentration of sulfuric acid at the level of 1-3 g/dm3. An increase in the concentration of iron (II) ions leads to a significant increase in full dynamic exchange capacity, even with a concentration of sulfuric acid of 8 - 13 g/dm3, full dynamic exchange capacity was at the level of 1.35 g-eq/dm3, which corresponds to the level of sorption of diluted solutions even in the absence of acid. However, the total concentration shows that the efficiency of sorption of metals from acidic solutions remains quite high and increases with the increase of the initial total content of sorbed ions. The main indicator used when choosing an ion exchange method is the possibility of effective regeneration of the cation exchange material. When using 5% solution of sulfuric acid already at the specific consumption of the regeneration solution, it was possible to achieve a degree of regeneration at the level of 95-98%, and when using 10% solution, the degree of regeneration reached 100%. According to the developed technological scheme, regeneration solutions are processed by precipitation into magnetite in a ferritizer reactor. To remove iron ions from concentrated iron-containing regeneration solutions by the ferrite method in order to obtain ferrite particles (magnetite) with maximum magnetic properties, a mixture of Fe (II) and Fe (III) sulfates was used with their concentration ratio K = [Fe2+]/[Fe3+] = 0.5, as a stable relationship between magnetic properties and sediment volume was noted. At maximum magnetic properties, the sediment volume is minimal, and vice versa. Obtaining highly dispersed magnetic particles from a mixture of ferric and ferric sulfates by precipitating them with 10% NaOH solution during heating allows to significantly reduce the duration of the process, simplify it and increase the productivity of the equipment. To obtain magnetic particles of copper ferrites from regeneration solutions by precipitation with alkali at normal temperatures, the concentration ratio K1 = [Fe2+]/[Cu2+] = 3.15-7.76 should be maintained. With an increase in the concentration of Cu2+ ions, there is an increase in the period of crystallization of the obtained sediments and their acquisition of magnetic properties. The formed ferrite material can be used for environmental purposes as a valuable raw material for carbon monoxide neutralization catalysts, as part of alkaline cement for concrete products, or sent for safe disposal. The obtained results on the application of ion-exchange extraction of iron and copper ions from acidic solutions of galvanic production are expedient as the first stage of complex ecologically safe processing of galvanic wastes with the production of ferritic materials for industrial use.

RECOVERY OF BORON WASTES WITH INORGANIC ACID

Approximately 73-74% of boron mineral reserves all over the world are located in the Western Anatolian region of Turkey, in the provinces of Eskişehir, Kütahya, Balıkesir, and Bursa. The most intense minerals extracted from these fields are colemanite, ulexite, and tincal minerals, respectively. The general principle in the recovery of these minerals is to extract the raw ore and obtain it by size reduction processes of concentrates in high grade. In addition to concentrates, boric acid (H3BO3) production is also possible in Balıkesir and Kütahya. The production of this acid in question includes a series of processes from dissolution with sulfuric acid at high temperatures to crystallization. In this study, except for the aforementioned high concentrations, boron recovery from clay waste, which is high in boron content and is collected from plant waste ponds, is investigated. For this purpose, ulexite-colemanite-containing slime wastes of the Bigadiç (Balıkesir) Plant were dissolved in 7% solids at 60°C in different sulfuric acid concentrations (1-6% H2SO4) and were obtained with 83-97% B2O3 recovery. When the boron wastes are evaluated, issues such as the discovery and establishment of a new waste pond/dam will be solved, the valuable content in the wastes will be recovered, and the environmental problems of boron and other contents in clay will be eliminated. This article includes information about the characterization of the structure by considering the dissolution of boron and other compounds, as well as obtaining boric acid from inorganic acid and boron wastes.

Study on Process Mineralogy of the Combined Copper Oxide Ore in Tibet and Acid Leaching Behavior with Calcium Fluoride

The Yulong copper deposit in Tibet is a typical porphyry copper deposit, with about 30 million tons of copper oxide ore in the surface layer. However, more than 40% of the copper resources are in a combination state, resulting in an extraction efficiency of only 50% for copper via the hydrometallurgical process. In this study, the process mineralogy of the combined copper oxide ore was systematically investigated and a calcium fluoride-enhanced leaching process is proposed to increase the leaching efficiency of the combined copper ore. The process mineralogy of the combined copper oxide ore was analyzed using various testing techniques, including chemical analysis, X-ray diffraction, and a process mineralogy parameter testing system (Mineral Liberation Analysis). The results revealed that limonite accounted for 86.12% of the sample, and 63.51% of the copper resource existed in the form of combined copper oxide in limonite. However, it is difficult for the uniformly distributed combined copper oxide in limonite to sufficiently make contact with sulfuric acid, which is the leaching agent, resulting in low copper leaching efficiency. The enhanced leaching behavior of the combined copper oxide ores was also investigated, thereby determining effective and economical enhanced leaching conditions. Under optimal conditions, at a grinding fineness ratio of −0.074 mm (accounting for 85%), liquid-solid ratio of 4:1, sulfuric acid concentration of 50 g/L, temperature of 30 °C, CaF2 dosage of 1% of the ore mass, and leaching time of 4 h, the copper leaching efficiency increased to 60.57%, which was 7.34% higher than that of atmospheric pressure leaching. Finally, the enhanced leaching slag was analyzed using an electron probe microanalyzer. It indicated that fluorine ions can erode the combined copper oxide ore and facilitate the diffusion of hydrogen ions inside the limonite, thereby achieving a strengthening effect.

Sustainable energy enhancement strategy from Chlorella vulgaris microalgae biomass resource

ABSTRACT Growing demand for renewable and sustainable energy sources has prompted research into bioethanol production as a viable alternative to hydrocarbon fuel for automobile engines. Based on their high carbohydrate content, Chlorella vulgaris microalgae were chosen for this study as a feasible biomass for bioethanol synthesis. After conducting microwave-based acid hydrolysis with varying acid concentrations of sulfuric acid (H2SO4) for 1–15 min, this study found that 3% H2SO4 for 5 min yielded the highest yield of reducing sugar (6.77 g/L). In this work, the RSM approach of central composite design (CCD) was utilized for modeling and optimization of ethanol fermentation and the MATLAB Simulink approach was employed for the simulation of ethanol fermentation. This study compared the effects of using Saccharomyces cerevisiae yeast for fermentation at different fermentation times (12 to 48 h), temperatures (28 to 32°C), and size of inoculum (0.5–1.5 g/L). Based on the actual and predicted results, the best conditions for fermentation were 36 h of time, 30°C of temperature, and 1.5 g/L of inoculum size. This gave the maximum ethanol concentration of 3.31 g/L. Furthermore, the RSM method provides minimum error and maximum R2 value results for ethanol production compared to MATLAB simulation prediction (MSP). In addition, residue biomass from biofuel production is evaluated for its suitability for a further form of biofuel production. This research explores the opportunities for zero-waste biomass utilization in the development of biofuels.

Innovative recycling of high purity silver from silicon solar cells by acid leaching and ultrasonication

Precious and scarce silver (Ag) is used as a front electrical contact in silicon solar panels. With massive amounts of solar panel waste coming to end-of-life, it is imperative to recover all the Ag from these modules. In this paper, we propose a novel method to easily reclaim Ag from end-of-life silicon solar cells using low concentration sulfuric acid (H2SO4) leaching followed by ultrasonication. Our process simplifies the Ag recycling procedure by directly recovering the Ag contacts from solar cells, eliminating the need for secondary precipitation/electrodeposition. First, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) was used to study the leaching and ultrasonication process on rejected solar wafers. Next, a solar panel from landfill was heated in a furnace to burn off the polymer encapsulant. The silicon wafers were then collected from the burning process and leached in 2 M H2SO4 at two different shaking speeds for 48 h at room temperature. Finally, the end-of-life silicon wafer pieces were collected, sonicated in water, and then the sonication water was centrifuged to show a proof-of-concept to recover the Ag contacts. Inductively coupled plasma optical emission spectroscopy (ICPOES) is used to monitor dissolved elements in the leachate as a function of time and shaking speed. XPS is used to evaluate the composition of the silicon cell wafer surface before and after H2SO4 leaching. SEM is used to image the recovered Ag contacts morphology and EDX confirms the recovered particles contain high amounts of Ag. A proposed schematic illustrates the authors’ hypothesis for the peeling mechanism.

Synergistic strategy of solute environment and phase control of Pb-based anodes to solve the activity-stability trade-off

The contradiction between the activity and stability of metal anodes exists extensively, especially in acid electrooxidation under industrial-level current density. Although the anode modification enhanced the initial activity of anodes, its long-term activity is limited by anode slime accumulation. Herein, a synergistic strategy, coupling the solute environment with the phase control of anodes, is proposed to achieve the trade-off between activity and stability of Pb-based anodes in concentrated sulfuric acid electrolysis. Non-exogenous Mn2+ motivated a series of positive behaviours of reactive-oxygen-species capture, anode reconstruction and corrosion-dependent activity alleviation. The synergistic effects, which are crystal phase-dependent, mainly benefit from the continuous self-healing ability of the specific crystal phase of MnO2 on the anodes by the coexisted Mn2+. Compared with Mn2+/α-MnO2, Mn2+/γ-MnO2 exhibited outperformed activity and stability in boosting oxygen evolution reaction (OER) and reducing hazardous pollutants, which resulted from the energy difference in the rate-determining step of OER and in the selectivity priority of Mn2+/MnO2 oxidation pathway. Interestingly, the pre-coated γ-MnO2 on the anode also presents excellent inheritance, guaranteeing the unchanged crystal phase of MnO2 and the high performance in ultra-low hazardous slime generation in subsequent Mn2+ oxidation. The sustainability of Mn2+/γ-MnO2 was proved in the operating hydrometallurgy conditions on Pb-based anodes. This strategy offers a promising approach for this common issue in electrooxidation-related areas.

Pengaruh Perlakuan Awal terhadap Karakteristik Bioetanol dari Limbah Kulit Singkong Karet (Manihot glaziovii)

Rubber cassava peel waste (Manihot glaziovii) has a high carbohydrate content, so it is feasible to convert it into bioethanol. In general, bioethanol production consists of four steps, pretreatment, hydrolysis, fermentation, and purification. The purpose of this study was to determine the suitable treatment for obtaining bioethanol with the finest characteristics from rubber cassava peel using three treatment variations, the pretreatment process with variations in the dissolving ratio of sodium hydroxide (NaOH) 0.5 M of 1:10; 1:12.5; and 1:15 (w/v), the hydrolysis process with various concentrations of sulfuric acid (H2SO4) of 0.15 N; 0.30 N; and 0.45 N, and the fermentation process with variations in the fermentation time for 3 days, 7 days, and 9 days. Based on the research results, the highest glucose content was 0.91%, with variations in dissolving NaOH 0.5 M 1:15 (w/v) in the pretreatment process and variations in the concentration of 0.30 N H2SO4 in the hydrolysis process, while the highest ethanol content was 68.05% at a fermentation time of 7 days.

Organosulfate produced from consumption of SO3 speeds up sulfuric acid–dimethylamine atmospheric nucleation

Abstract. Although sulfuric acid (SA) and dimethylamine (DMA)-driven nucleation mainly dominates the new particle formation (NPF) process in the atmosphere, seeking the involvement of other gaseous species remains crucial for a better understanding of the NPF. Organosulfate has been detected in the gas phase and abundantly in atmospheric fine particles. However, its molecular formation mechanism and its impact on the NPF are still much less understood. Here, we explored the gas-phase reaction of glycolic acid (GA) with SO3 and evaluated the enhancing potential of its products on the SA–DMA-driven NPF using a combination of quantum chemical calculations and kinetics modeling. We found that the considerable concentration of glycolic acid sulfate (GAS) is thermodynamically accessible from the reaction of GA with SO3, efficiently catalyzed by SA or H2O molecules. The produced GAS can form stable clusters with SA and DMA and speeds up the nucleation rate of the SA–DMA system obviously. Notably, the enhancement by GAS in the SA–DMA-based particle formation rate can be up to ∼ 800 times in the region where the concentration of SA is about 104 molec. cm−3. Supported by observations of atmospheric NPF events at Mt. Tai in China, our proposed ternary GAS–SA–DMA nucleation mechanism further indicates that the organosulfates produced from the consumption of SO3 may play an important role in the unexpected high NPF rates observed in areas with relatively low concentrations of SA. The presented reaction and nucleation mechanisms provide a new feasible source of organosulfates in atmospheric new particles. Based on our findings, the impact of organosulfates on the atmospheric NPF in multiple regions around the world was estimated and discussed.

Stability of 20 Biogenic Amino Acids in Concentrated Sulfuric Acid: Implications for the Habitability of Venus' Clouds.

Scientists have long speculated about the potential habitability of Venus, not at the 700K surface, but in the cloud layers located at 48-60 km altitudes, where temperatures match those found on Earth's surface. However, the prevailing belief has been that Venus' clouds cannot support life due to the cloud chemical composition of concentrated sulfuric acid-a highly aggressive solvent. In this work, we study 20 biogenic amino acids at the range of Venus' cloud sulfuric acid concentrations (81% and 98% w/w, the rest water) and temperatures. We find 19 of the biogenic amino acids we tested are either unreactive (13 in 98% w/w and 12 in 81% w/w) or chemically modified in the side chain only, after 4 weeks. Our major finding, therefore, is that the amino acid backbone remains intact in concentrated sulfuric acid. These findings significantly broaden the range of biologically relevant molecules that could be components of a biochemistry based on a concentrated sulfuric acid solvent.

Fabrication of pore-filling cation-exchange membrane from waste polystyrene and Spunbond Meltblown Spunbond (SMS) non-woven polypropylene fabric as the substrate

Commercial ion-exchange membranes are typically thick, possessing limited mechanical strength, and have relatively high fabrication costs. In this study, we utilize a three-layer polypropylene fabric known as Spunbond Meltblown Spunbond (SMS) as the substrate. This choice ensures that the resulting membrane exhibits high strength and low thickness. SMS substrates with various area densities, including 14.5, 15, 17, 20, 25, and 30 g/m2, were coated with different concentrations of waste polystyrene solution (ranging from 5 × 104 to 9 × 104 mg/l) before undergoing sulfonation using concentrated sulfuric acid. The physicochemical and mechanical properties of the membrane were characterized and compared with those of commercial Neosepta CMX and Nafion-117 cation-exchange membranes. Remarkably, the fabricated membrane exhibited good performance compared to commercial ones. The cation-exchange capacity (2.76 meq/g) and tensile strength (37.15 MPa) were higher, and the electrical resistance (3.603Ω) and the thickness (130 μm) were lower than the commercial membranes.

Study Nickel recycling and leaching of metals from Eco-Friendly Nickel-metal hydride battery by response surface method

In this research, nickel metal hydride batteries were designed in certain sizes and components. In order to evaluate the quality and quantity of the designed batteries, the metal mold was cut lengthwise from the inner layers of the battery. The active materials of the electrode used in this work were black powder and nickel alloy, which were manually separated from the batteries. Battery black powder was investigated by X-ray diffraction analyzes and the presence of nickel as the main constituent of black powder was confirmed. The results of atomic absorption showed that more than 99 % of the alloy were a nickel. In this study, black powder was leached with sulfuric acid. The influence of parameters such as temperature, sulfuric acid concentration and liquid to solid ratio (L/S) on nickel extraction in a discontinuous system at two-phase constant contact time were studied. According to the results, the parameters of sulfuric acid concentration, temperature, liquid to solid ratio and the interaction of acid concentration with itself were important in nickel extraction. Optimal leaching conditions included a temperature of 60 °C, an acid concentration of 1.42 mol/L and a liquid to solid ratio of 10 mL. Under optimal conditions, the leaching efficiency was 81.25%, which was better compared to the batteries with other models and brands. In the next step, the purification of the leaching solution was investigated by sodium carbonate and a combination of sodium carbonate and sodium hydroxide. The results of atomic absorption showed that more than 83% of cobalt, manganese and zinc were removed and more than 98% of nickel ions were recycled, which was better than commercial batteries of various brands. Because the return of cobalt, manganese and zinc to nature by other batteries is higher than the designed battery and the recycling percentage of nickel ions is lower, these results are very important in terms of environmental safety.

Catalytic action of hydronium-ion in rice straw pretreatment and enhancement of enzymatic hydrolysis and ethanol production

The present investigation will focus on the catalytic effect of hydronium ion during liquid-water/ dilute sulfuric acid/ferric chloride pretreatment (LWP/ SAP/ FCP) on the hydrolysate and pretreated rice straw. The overall pretreatment process has been represented as a sequential catalytic reactions. The temperature range of pretreatment is varied in the range of 140–180 °C and the concentration of dilute sulfuric acid and ferric chloride is 0.1 M. The first order rate constants of xylan and glucan degradation have been determined for LWP/ SAP/ FCP. The maximum xylan and glucan conversion of 96.8% w/wand 31.4%w/w respectively are achieved for FCP at 180 °C. Xylose, glucose, furfural, 5-hydroxymethyl furfural, acetic acid and formic acid appear as the main products for all pretreatments. Only in case of FCP levulinic acid also appears as a hydrolysis product. The thermal characteristics, functional groups, crystallinity, surface morphology of untreated and pretreated rice straw have been evaluated. Among all pretreatment processes under study, the highest values of glucose yield of 78.96% (w/w) using enzymatic hydrolysis and 83.79% of theoretical yield of ethanol using Saccharomyces cerevisiae have been achieved for ferric chloride pretreatment.

The study on the shortcut approach for cooperative disposal of arsenic-rich copper dust and waste acid to prepare high-purity copper

The copper dust derived from the double-flash copper smelting process contains high level of arsenic with almost zero positive potential impurities. This study explores a new process for the preparation of high-purity copper through selective leaching of arsenic-rich copper dust with waste acid-purification-electrodeposition. Furthermore, the study also explores the causes and solutions for recurrent occurrence of excessive Hg impurity content. The results indicate that, the high-purity copper that meets standard 6 N (China) requirements and exhibits smooth surface, dense crystallization, and uniform color can be obtained under the optimal conditions of 200 A/m2 current density, electrolyte sulfuric acid concentration of 120 g/L, additive dosage of 120 g/t·Cu, electrolysis temperature of 50 °C, electrode spacing of 45 mm, endpoint Cu2+ concentration of 30.50 g/L, with C1 used as active adsorbent to purify the electrolyte. The current efficiency can be up to 99.65 %, with average tank voltage of 1.87 V and electrical energy consumption of 1582.93 kW h/t⋅Cu. There will be good environmental and economic benefits with this process of co-disposal and high-value recovery of arsenic-rich copper dust and waste acid.

Effect of Calcination Temperature on Sulfonated Lignin Catalyst Preparation for Glucose Ethanolysis to Ethyl Levulinate

An abundance of biomass material is generated globally which has the potential to be converted to various bio-based chemicals including ethyl levulinate (EL). EL is well known as a sustainable fuel additive and can be produced from glucose, a biomass derivative in an ethanolysis reaction throughout acidic catalysis. In this study, sulfonated lignin carbon catalysts were used to catalyze the ethanolysis of glucose to synthesize EL. The catalysts were prepared from lignin via calcination at different soaking temperatures (400 to 600 °C) for 1 h to produce carbon material, followed by sulfonation with concentrated sulfuric acid at a 1:10 (carbon-to-acid, g/mL) ratio. The catalysts were tested for glucose ethanolysis reaction in a batch reactor equipped with a thermocouple on selected conditions (0.4 g of glucose, 40 mL of ethanol, 1.2 g of catalyst, and 6 h reaction) at 180 °C and their performance was evaluated according to the EL yield obtained. Then, the catalyst characterization was conducted for the selected catalyst using Fourier transform infrared spectroscopy (FTIR), ion-exchange titration, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), nitrogen sorption analysis, and Thermalgravimetric analysis (TGA). The result showed that the performance of the sulfonated lignin carbon catalysts was reduced, especially at higher soaking calcination temperatures. The catalyst prepared from lignin carbon calcined at 450 °C, (CS450) was able to provide a high EL yield of 22.54 mol% with a good acidity of 1.0 mmol/g, a high surface area of 229.95 m2/g, and suggested thermal stability at 300 °C. The results indicated that the sulfonated lignin carbon catalyst could be used as a solid acid catalyst for glucose ethanolysis reaction, yet further catalyst modification is required in the future to enhance its performance for higher EL yield.

Effect of successive recycling and reuse of acid liquor for the synthesis of graphene oxides with higher oxygen-to-carbon ratios

Graphene has recently drawn exponential attention due to its surprising physicochemical properties and diversified field of applications. Although graphene oxides (GOs), itself is an exclusive material, it is also an intermediate product for the production of reduced graphene oxides (rGOs), graphene and their derivatives, which are other more superficial materials. In this study, GOs with higher oxygen to carbon ratios were synthesized following the Tour method, where the excess feed acid liquor (FAL) of mixed concentrated sulfuric and orthophosphoric acids at a ratio of 90:10 was recovered from the reaction slurries by applying the centrifugation technique. About 80–90 % of the FAL was recycled and reused as feed for the subsequent batches. The changes in the properties of FAL for the five consecutive recycling and reuse were studied. The properties of recycled FALs were investigated by measuring density, moisture content, pH, and ion concentration. The consecutive recycling of FALs tends to increase the moisture content about 0.5% in each recycles. Ion-chromatography (IC) was used to measure the variation in SO42− and PO43− ions in the FALs. The H2SO4 reacts with KMnO4 and crystalized out from the recovered FAL faster than the phosphoric acid. So, sulfuric acid content in the makeover FALs must be greater than primary FAL. The product GOs were characterized using FT-IR, FT-Raman, UVVis, STA, SEM, XPS, Zeta-potential, and particle size analyzers. The variation of the properties of GOs with the changes in the reaction parameters such as temperature and time were investigated and correlated with the product yield. It was observed that the effect of temperature on the reaction rate was found to be negatively and positive with the reaction time. The oxygen-to-carbon atomic ratio from XPS analysis was found 66.7%, which supported the increase in product yields 66.9% in the experimental results. The effect of acid concentration, reaction temperature, and time on the GOs properties were satisfactory, correlated, and easily controllable with the reaction conditions. A higher extent of oxidation and enhanced product yields 65–70% were observed at 60–70 °C and 14–18 h. A mixture of nano- and macro-molecular GOs was obtained, and their compositions were easily controllable and separable by controlling the reaction conditions. A correlation was made among the properties of synthesized GOs, FAL, and recycled FAL and reaction conditions.

Effect Mechanism of Electrocardiogram-Based Intravenous Single-Walled Carbon Nanotubes on Cardiac Function

This research was aimed to adopt electrocardiogram (ECG) and other techniques to explore the effects and mechanisms of single-walled carbon nanotubes (SWCNTs) and their carboxylation modification (C-SWCNTs) on cardiac function in rats. The SWCNTs were oxidized to C-SWCNTs by concentrated sulfuric acid and concentrated nitric acid. The morphology, surface charge, surface group, and water dispersibility of the samples were characterized. Subsequently, 40 SD rats in a 1:1:1:1 ratio were assigned into sham (intravenous injection of 5% glucose), SWCNT (intravenous injection of 2 mg/mL SWCNT glucose dispersion), C-SWCNT (intravenous injection of 2 mg/mL C-SWCNT glucose dispersion), and C-SWCNT+YM groups (treatment in C-SWCNT group was supplemented with an additional 1 mg/mL store-operated calcium entry (SOCE) blocker YM-58483/BTP2). The tail arterial pressure of rats in each group was detected. Left heart function and hemodynamics were detected by cardiac color ultrasonography. Heart parameters were detected by ECG lead II, and the pathological morphology of the heart was detected by hematoxylin-eosin staining. The levels of proteins related to the cardiac calcium signaling were detected by western blot. The results showed that the particle size distributions of SWCNTs and C-SWCNTs were uniform, and C-SWCNTs had better water dispersibility and a negatively charged surface. The results of caudal arterial pressure showed that SBP, DBP, and MBP of the caudal arteries in the SWCNT and C-SWCNT groups were markedly superior to those in sham group (P < 0.05). Cardiac function results showed drastic decreases in LVDd, EF, EDV, SV, and CO and great increases in LVDs, AV-BVmax, and PV-BVmax in the SWCNT and C-SWCNT groups relative to sham group (P < 0.05). The ECG results showed that relative to those in sham group, the amplitudes of the P wave and ST segment in the SWCNT and C-SWCNT groups were increased, the QRS and RR intervals were greatly prolonged, and the amplitude of the R wave was greatly decreased (P < 0.05). Western blot results showed that the SWCNT and C-SWCNT groups had drastically increased protein levels of ORAI-1 and STIM-1 in the heart versus sham group (P < 0.05). The changes in various cardiac parameters in C-SWCNT group were more prominent, and the cardiac pathological score increased markedly versus that in SWCNT group. The protein levels of ORAI-1 and STIM-1 increased notably (P < 0.05). The changes in various cardiac parameters in C-SWCNT+YM group were notably enhanced versus those in the SWCNT and C-SWCNT groups, the cardiac pathological score was obviously reduced, and the protein levels of ORAI-1 and STIM-1 were substantially decreased (P < 0.05). SWCNTs and C-SWCNTs both had cardiotoxic effects in rats, and C-SWCNTs had more obvious toxic effects. Nevertheless, the SOCE inhibitor YM-58483/BTP2 was able to enhance C-SWCNT-induced cardiac dysfunction by inhibiting the expression of calcium signaling-related proteins and affecting the changes in ECG parameters.

High Thermoelectric Performance and Flexibility in Rationally Treated PEDOT:PSS Fiber Bundles

Organic thermoelectric fibers have great potential as wearable thermoelectric textiles because of their one-dimensional structure and high flexibility. However, the insufficient thermoelectric performance, high fabrication cost, and mechanical fragility of most organic thermoelectric fibers significantly limit their practical applications. Here, we employ a rapid and cost-effective wet-spinning method to prepare dimethyl sulfoxide-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fiber bundles, followed by rational post-treatment with concentrated sulfuric acid (98% H2SO4) to enhance their thermoelectric performance. The wearable fiber bundles composed of multiple individual PEDOT:PSS fibers have effectively reduced resistance and overall high tensile strength and stability. Rational treatment with H2SO4 partially removes excessive PSS, thereby increasing the electrical conductivity to 4464 S cm‒1, while the parallel bundle is also a major factor in improving the power factor of up to 80.8 μW m‒1 K‒2, which is super-competitive compared with those of currently published studies. Besides, the thermoelectric device based on these fiber bundles exhibits high flexibility and promising output power of 2.25 nW at a temperature difference of 25 K. Our work provides insights into the fabrication of all-organic flexible high-conductivity textiles with high thermoelectric properties.Graphical

ANALYSIS OF BIOPOLYMER FROM CASSAVA PEEL USING CROSSLINKER CR3+ AS AN ALTERNATIVE MATERIAL IN WATER CONING

Polymers play a crucial role in chemical processes for controlling water condensation. This study chose biopolymer materials derived from cassava peels due to their superior environmental sustainability compared to synthetic polymers commonly used in water conditioning. While synthetic polymers are frequently employed for water conditioning, they may pose adverse environmental impacts. The chemical polymer introduced into the water formation involves the injection of a chromium (Cr3+)-based agent, enhancing viscosity and impeding water movement. The primary objective of this study is to utilize cellulose from cassava peels as the main component for producing sodium carboxymethyl cellulose, aimed at mitigating water coning. The synthesis and hydrolysis processes involve the use of sulfuric acid and cassava peels as biopolymers. The Fourier-Transform Infrared (FTIR) spectroscopy test revealed the presence of functional groups such as OH, C-H, C-O, and C=O in the cassava epidermis. The cellulose yield ranged from 62.3% to 90%, demonstrating a proportional decrease in yield weight with increased sulfuric acid concentration. Concentrations of 1,000, 2,000, and 3,000 ppm were employed, with salinity set at 5,000, 10,000, and 15,000 ppm, respectively. These conditions were maintained at 60, 70, and 80°C. The compatibility of solutions with concentrations of 1,000 and 2,000 ppm was assessed. The results indicate that solutions at 1,000 and 2,000 ppm concentrations are sui, showing no precipitate and clear characteristics.

Mechanism for leaching of fluoride ions from carbon dross generated in high-temperature and low-lithium aluminum electrolytic systems

Carbon dross, a hazardous solid waste generated during aluminum electrolysis, contains large amounts of soluble fluoride ions for the main components of the electrolyte (such as Na3AlF6 and NaF). Response surface methodology (RSM) was used to investigate the mechanism for fluoride ion leaching from carbon dross via water leaching, acid leaching and alkali leaching, and the kinetic and thermodynamic principles of the leaching process were revealed. The RSM predicted the optimum conditions of water leaching, alkali leaching and acid leaching, and the conditions are as follows: temperature, 50 °C; shaking speed, 213 r·min-1; particle size, 0.075 mm; shaking speed, 194 r·min-1; liquid-solid ratio, 12.6 mg·L-1; sodium hydroxide concentration, 1.53 mol·L-1; liquid-solid ratio, 25.0 mg·L-1; sulfuric acid concentration, 2.00 mol·L-1; and temperature, 60 °C，and actual results which were almost consistent with the predicted results were gained. The fluoride ions in the alkaline and acid leaching solutions were mainly the dissociation products of fluorides such as Na3AlF6, Na5Al3F14 and CaF2, as indicated by thermodynamics calculations. In particular, the fluoride compounds dissolved in alkali solution were Na3AlF6, Na5Al3F14, AlF3, ZrF4, K3AlF6, while the acid solution could dissolve only Na3AlF6 and CaF2. The leaching kinetics experiments showed that the leaching rate fit the unreacted shrinking core model [1–2/3α-(1-α)2/3 =kt] and that the leaching process was controlled by internal diffusion. This study provides theoretical guidance for the removal of soluble fluoride ions from carbon dross and will also assist in the separation of electrolytes from carbon dross. Environmental ImplicationCarbon dross, a hazardous waste generated during the aluminum electrolysis production process, contains a large amount of soluble fluoride. Improper storage will lead the fluoride ions pollution in soil, surface water or groundwater under the direct contact between carbon dross and rainfall, snow or surface runoff. The influence of wind will cause carbon dross dust to pollute further areas. With the human body long-term contact with fluoride ion contaminated soil or water, human health will be seriously harmed.

Pretreatment of refractory gold ore by curing with concentrated sulfuric acid

Pretreatment of refractory gold ore by curing with concentrated sulfuric acid