Hydrochloric Research Articles

Recovery of rhenium and tungsten from calcium tungstate containing rhenium via hydrochloric acid decomposition

ABSTRACT In view of calcium tungstate containing rhenium generated during the recovery process of tungsten−rhenium alloy waste, rhenium and tungsten were separated by hydrochloric acid decomposition, followed by ion exchange enrichment and evaporation crystallization for rhenium recovery; then, tungsten was recovered by calcining the obtained tungstic acid. The results showed that the leaching efficiency of Re reached 99.76% for HCl concentration of 2.7 mol/L, liquid-to-solid ratio of 26:1, temperature of 80°C, and time of 5 h. The Re mass percentage in tungstic acid product decreased to 0.0005%. After adsorbed by A170 resin and desorbed by 10% ammonium hydroxide, the Re concentration of the leaching solution was enriched from 176.50 mg/L to 4.61 g/L with the enrichment ratio of 26.12; the adsorption and desorption ratios of Re were 80.83% and 96.94%, respectively. The SEM morphology of NH4ReO4 crystals crystallized from the enriched solution was dendritic. The decomposition reaction conforms to shrinking core model, and the activation energy was calculated as 53.46 kJ/mol with internal diffusion and chemical reaction as the rate-controlling step. The submicron spherical-like tungsten trioxide, with average particle size of 195.53 nm-540.10 nm, was obtained by calcining the tungstic acid at 900°C and air atmosphere for 0.5 h−5 h.

Fractionation methods of eucalyptus kraft lignin for application in biorefinery

Abstract Kraft lignin has high dispersity and low reactivity. This study aimed to obtain more homogeneous and modified chemical fractions from the application of fractionation methods using organic solvents and acid precipitation. Organic solvents used were ethyl acetate, ethanol, methanol and acetone. The pHs tested were 9, 7, 5, 3 and 1, by adding hydrochloric acid. The fractions were characterized of acid-soluble and insoluble lignin, carbohydrates, ashes, elemental analysis and by Py-GC/MS. All fractions obtained in both fractionation methods showed higher carbon contents, higher purity and lower S/G ratio than the corresponding initial materials, characteristics that are very favorable for the application in biorefinery. Acetone-soluble (sequential) and pH 1 (one-step) precipitated fractions are the most promising for carbon fiber production. Fractions soluble in ethyl acetate (one-step) and insoluble at pH 3 and 1 (sequential) appear to be the most appropriate for applications that require good oxidative properties. The fractions soluble in ethanol (one-step), methanol (one-step), acetone (one-step) and precipitated at pH 9 (one-step) and pH 5 (sequential) are the ones that allow better chemical substitution in obtaining bioproducts. Fractions soluble in ethanol (sequential) and precipitated at pHs 5 and 1 (sequential) are not of commercial interest due to their low yield.

How does lime and rice straw compost application affect arsenic uptake in rice after a century of cropping under flooded conditions?

ABSTRACT Arsenic (As) uptake by rice is mainly controlled by the redox potential, amount of iron- and aluminum-bearing minerals and silicon (Si) availability in paddy soil. These soil properties are altered upon long-term continuous rice cultivation, and differences in soil properties arising from different agricultural management practices can influence As behavior in soils. This study aimed to clarify how long-term soil management with and without liming and rice straw compost application influences As uptake by rice. Soil and rice samples were collected from plots with continuous application of NPK mineral fertilizer with and without lime and from plots applied with NPK mineral fertilizer and lime with 750 and 2250 g m−2 straw compost in a long-term experimental paddy field established in 1926. Concentrations of As in rice shoots and panicles from the 92nd to 97th cropping seasons were determined. Hydrochloric acid (1 mol L−1 HCl)-extractable As and pseudototal As concentrations were also determined in select archived soil samples collected from the 52nd to 97th cropping seasons and for the 97th cropping season, respectively. Arsenic uptake by rice was lowest in the plots with lime and 2250 g m−2 rice straw compost application because application of excess organic amendments induced strong reducing conditions, which resulted in a loss of As and Fe minerals from the soil. In this plot, As uptake was lower in the year when no precipitation occurred over a longer period of days during the mid-summer drainage. Despite the increase in the uptake of Si with the application of rice straw compost, the ability of Si to mitigate As uptake was not apparent. The uptake of As by rice in the plot without liming was lower although this plot had a higher concentration of HCl-extractable As in the soil, possibly because As dissolution under flooded conditions was suppressed by the presence of low-crystalline Al minerals. In conclusion, As uptake in rice decreased with the long-term application of excess rice straw compost and in the absence of liming.

The Sweet Spirits of the Mineral Acids: Diethyl Ether, Ethyl Nitrite, and Chloroethane. Late Medieval-Early Modern Organic Chemistry.

The "sweet spirits" of sulfuric, nitric, and hydrochloric acids, viz. diethyl ether, ethyl nitrite, and chloroethane, have a history dating back to the late Middle Ages. The compound variously known as philosophorum spiritus vini, aqua Lulliana, Paracelsus' Schwefel süss, Cordus' dulce Vitrioli oleum, and Frobenius' æther is identical with diethyl ether. The spiritus nitri dulcis was discovered by Glauber, although it was first described clearly by Kunckel. It is largely ethyl nitrite. Spiritus salis dulci was discovered by Paracelsus and is identical with chloroethane. The historical preparations of the mineral acids as well as their sweet spirits obtained by reaction with ethanol are described in detail with particular emphasis on the experimental methods and the pyrolysis/distillation apparati used. These preparations of derivatives of ethanol are among the earliest examples of organic synthesis, although the true nature of the compounds was not recognized until the 19th century.

Achieving 3-D Structural Uniformity in Cellulose Gel Beads via Salt Screening

Cellulose microgel beads fabricated using the dropping technique suffer from structural irregularity and mechanical variability. This limits their translation to biomedical applications that are sensitive to variations in material properties. Ionic salts are often uncontrolled by-products of this technique, despite the known effects of ionic salts on cellulose assembly. In this study, the coagulation behavior of cellulose/salt solutions was explored as a way to combat these challenges. An ionic salt (NaCl) was added to a cellulose solution (cellulose/NaOH/urea) prior to coagulation in a hydrochloric acid bath. Quantification of the bead geometry and characterization of the pore architecture revealed that balancing the introduction of salt with the resultant solution viscosity is more effective at reducing structural variability and diffusion limitations than other pre-gelling techniques like thermal gelation. Three-dimensional visualization of the internal pore structure of neat cellulose, thermo-gel, and salt-gel beads revealed that adding salt to the solution is the most effective way to achieve 3-D structural uniformity throughout the bead. Coupled with nanoindentation, we confirmed that the salt produced during coagulation plays a critical role in mechanical variability, and that adding salt to the solution before dropping into the coagulation bath completely screens this effect, producing uniform microgel beads with reproducible mechanical properties.

Results of phytochemical screening in aerial organes of Bidens frondosa L.

Introduction. The work presents the results of a comprehensive study of the grass of Bidens frondosa L. of the family Asteraceae, growing on the territory of the Krasnodar Territory and the Republic of Adygea. Objective: to carry out phytochemical screening of the main groups of biologically active substances and quantitative determination by methods of spectrophotometry and HPLC. Material and methods. The plant material is represented by dried air-shadow grass of the Bidens frondosa L. (September 2020 and 2022). Samples of herbarium collected by the authors are at the Department of Pharmacognosy, Botany and Technology of Phytotherapy of Pyatigorsk medical and pharmaceutical institute. Results. Complex studies have been carried out, including the determination of commodity quality indicators of aerial organs Bidens frondosa L. Determination of humidity in the raw material content is 9.9%. The definition of common ash is 7.3%. The ash content, insoluble in 10% hydrochloric acid solution, is 7%. In alcohol and aqueous extracts of herbs Bidens frondosa L. have been found: flavonoids, polysaccharides and tannins. UV spectrophotometry and HPLC were used to quantify the flavonoid sum content. The amount of flavonoids per routine in alcohol extraction was 3.13%. The herb B. frondosa contains gallic acid, chlorogenic acid, caffeic acid, rutin, luteolin-7-glycoside and quercetin. The substance whose content is greatest in the raw material is unknown. Presumably, this compound is Okanin from the group of chalcons. Probably, this compound has such a pronounced anti-allergic effect. Conclusion. The phytochemical analysis of the main groups of biologically active substances of the olic sequence of grass was conducted. During the work, the presence of flavonoids, polysaccharides and tannins was determined. The quantitative content of flavonoids, сhalcons and polysaccharides is determined.

A simple and efficient method for palynological sample preparation

AbstractThe extraction of organic microfossils is a process that requires techniques based on the elimination of the mineral components of the rock (mainly silicates and carbonates) and the subsequent concentration of the microfossils. These techniques are very diverse and have in common the dissolution of the rock (maceration) with hydrofluoric acid and concentrated hydrochloric acid to extract the organic matter, which is potentially made up of dispersed organic matter and organic walled microfossils. In this process, there are at least two fundamental objectives. First, that the process respects the fidelity of the organic microfossil record (diversity and preservation). Second, effective elimination of dispersed organic matter, obtaining the maximum concentration of microfossils and microscopic slides with a homogeneous dispersion that allows optimal observing conditions. The method described in this paper is based on a filtration process of the organic matter resulting from the maceration process, employing polyester filters and a vacuum inversion system. In the standard vacuum process, the dispersed organic matter clogs the pores of the filter. The vacuum inversion injects filtered water that unclogs the pores of the filter vessel. The alternation between normal and reverse vacuum results in the progressive elimination of the dispersed organic matter and the concentration of the organic microfossils in a rapid and non-aggressive process.

Twenty-eight days later: The recovery of DNA from human remains submerged in aggressive household chemicals.

Aggressive chemicals intended for cleaning pools or unclogging drains contain high concentrations of dangerous compounds, leading to their nefarious use in dissolving human remains in some criminal cases. The use of these readily accessible household cleaners to destroy human remains and hide evidence of a crime presents a considerable challenge for human identification. However, research on the success of recovering DNA from such remains is limited. Therefore, we investigated the effects of submerging partial human remains (including whole heads, forearms, and hands) in five different household products: bleach, Rid-X® septic treatment, lye drain opener, sulfuric acid drain opener, and muriatic acid (hydrochloric acid) pool cleaner. We evaluated the impact of each chemical, focusing on visual changes, DNA recovery, and the potential for successful human identification through traditional STR or mitochondrial DNA analyses. Exposure to all chemicals altered the appearance of the remains, but DNA recovery was still possible across various time periods, up to 28 days. Human remains exposed to bleach, Rid-X®, and lye produced full STR profiles after 4 weeks. Sulfuric acid shortened this time to 3 weeks, while hydrochloric acid, the most damaging chemical, limitedfull STR profile recovery to just the first 3 days of exposure. This study demonstrates that although differences in the rate of damage occur depending on the amount of tissue introduced, volume of chemical used, and the specific chemical of choice, DNA-based human identification of remains treated with everyday household cleaners is likely, particularly if bone fragments are recovered.

Deviations from ideality in solutions of dicarboxylic acid salts modeled within a BiMSA theory for flexible chains.

The binding mean spherical approximation theory is used to describe the thermodynamic properties of dicarboxylic acid salts by adding a chain term in the free energy. The dianions in these solutions are modeled as flexible charged chains composed of two, three, or four spheres. Five aqueous solutions of such salts are studied in different concentration ranges: dipotassium oxalate, disodium malonate, disodium succinate, potassium tartrate, and sodium tartrate. A description of the experimental deviations from ideality (osmotic and activity coefficients) for these salts is obtained. The model is compared with a previous one that does not include a chain contribution. It is found that the model with a chain contribution provides a more physically sound framework.

Assessing the Photocatalytic Degradation of Penconazole on TiO2 in Aqueous Suspensions: Mechanistic and Ecotoxicity Studies in Aerated and Degassed Systems

Penconazole (C12H15Cl2N3) is widely used to prevent fungal infection of fruits. Since this toxic fungicide is recalcitrant to biological degradation, it has harmful impacts on aquatic ecosystems. TiO2-based heterogeneous photocatalysis proved to be an efficient method for its mineralization. To monitor the processes occurring under the influence of illumination, the light absorbance, the pH, and the TOC of the samples were measured. The concentration of the model compound and the degradation products were determined by HPLC and IC. Penconazole did not decompose under UV light (λmax = 371 nm) without a catalyst. In the presence of TiO2, mineralization took place. The initial degradation rate in air (7.7 × 10−4 mM s−1) was 5 times higher than under argon. The formation rate of hydrochloric acid (1.04 × 10−3 mM s−1) in the former case significantly contributed to the acidification of the liquid phase. NH4+ also formed, at the rate of 5.9 × 10−4 mM s−1, and very slightly transformed to NO3−. Due to the intermediates identified by HPLC-MS, hydroxylation, H abstraction, and Cl elimination are involved in the degradation mechanism, in which photogenerated HO● radicals, conduction-band electrons, and (under air) superoxide radical anions (O2●−) play considerable roles. The intermediates proved to be much less toxic than penconazole.

Efficacy of Biorational Insecticides and Entomopathogenic Fungi for Controlling Cassida vittata Vill. (Coleoptera: Chrysomelidae) in Sugar Beet Crops.

The sugar beet flea beetle, Cassida vittata Vill. (Coleoptera: Chrysomelidae), is a major pest in Morocco's sugar beet crops and is primarily controlled with chemical insecticides despite environmental concerns. Our aim was to assess the impact of three biorational insecticides (spinosad at 30-7.5cc/hL, mineral oil at 2000-250cc/hL, and potassium salts of fatty acids at 1500-375cc/hL) and two entomopathogenic fungi (Alternaria murispora and Alternaria destruens applied at 1.0 × 108, 5.0 × 107, and 2.5 × 107 conidia mL-1) both individually and in combination on C. vittata adults. All treatments were conducted at 25 ± 1°C, with mortality recorded over 10days. Conidial germination was highest for A. murispora with mineral oil (98.4%). Alternaria destruens showed consistently high germination across treatments. At 100% concentration, A. murispora + mineral oil and A. destruens + mineral oil treatments achieved 96.67 and 92.00% mortality, respectively. Median survival times (MST) for A. murispora were 6.0days at 100% concentration, increasing to 10.0days at lower concentrations, while A. destruens had a consistent 10.0days MST. LC50 for A. murispora was 1.3 × 107 conidia mL-1 alone, increasing to 2.2 × 107 with spinosad, but remained 1.7 × 107 with potassium salts of fatty acids. For A. destruens, LC50 was 4.2 × 107 conidia mL-1 alone, decreasing to 1.5 × 107 with mineral oil, and 3.1 × 107 with potassium salts of fatty acids. Combining A. murispora with mineral oil and potassium salts of fatty acids enhanced efficacy against C. vittata.

Influence of sand type on acid resistance and capillary absorption capacity

This study aims to investigate the effect of binary and ternary combinations of river sand (RS), crushed sand (CS) and dune sand (DS) on the physical and mechanical performance of concrete subjected to acidic curing environments. The RS was replaced by CS and DS in different mass proportions. The five concrete mixtures M21(RS), M04(0.6CS + 0.4DS), M10(0.2RS + 0.6CS + 0.2DS), M15(0.4RS + 0.6CS) and M16(0.6RS + 0.4DS) were prepared. The sorptivity was evaluated by measuring the sorptivity coefficient (S, cm*s-0.5) after 28 days of submersion in distilled water. Concrete specimens were submersed in distilled water, 5% sulfuric acid (H2SO4), and 5% hydrochloric acid (HCl) for up to 180 days in order to test their acid resistance. Visual inspection, changes in mass and changes in compressive strength were used to evaluate the specimens' resistance to acid attack. The results indicated that replacing RS with CS led to an increase in sorptivity, while replacing RS with DS resulted in a decrease. When both CS and DS were used in place of RS, acid resistance in 5% HCl solution decreased. In 5% H2SO4 solution, substituting RS with CS reduced mass loss, but replacing RS with both CS and DS weakened the concrete's compressive strength.

Corrosion inhibition effects of celery (Apium graveolens) seeds extract on carbon steel in acid medium

The present study highlights the inhibition performance of celery seeds (CS) extract on carbon steel immersed in 1M HCl, using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. This extract is selected due to biodegradable, renewable, and foremost aspect, is safe towards both the human being and environment. The studied inhibitor was easily extracted by using a simple aqueous extraction procedure. The experimental results show that the investigated inhibitor can effectively retard the corrosion process that occurs to carbon steel in hydrochloric acid solution. Electrochemical impedance spectroscopy (EIS) spectra showed that inhibition efficiency increases with the increasing of (CS) extract concentration. Among the studied inhibitor showed maximum inhibition efficiency of 96,86% at 250 ppm. Polarization curves indicate that (CS) extract acted as mixed type of inhibitors with a predominant effect on the anodic reactions. Basic calculations for the adsorption studies were also carried out. The adsorption of the extract onto carbon steel surface followed the Langmuir adsorption isotherm.

Chloride Interferences in Wet Chemical Oxidation Measurements: Plausible Mechanisms and Implications.

Wet chemical oxidation (WCO) methods measure total organic carbon (TOC) in aqueous solutions through the formation and detection of carbon dioxide (CO2). Prior research documents chloride (Cl-) interference during WCO. However, the mechanism that determines WCO interference is not established. We investigate WCO and find that formic acid exhibits TOC recovery (89-108%) within measurement uncertainty in the presence of Cl-, while acetic acid recovery is substantially reduced (3-67%). We postulate that chlorine radical (•Cl) formation during WCO alters oxidation pathways for organic compounds with methyl groups to form stable halogenated organic species that are thus not detected as CO2, reducing observed TOC recovery. We develop a kinetic model of elementary step reactions that reproduces observed TOC recoveries at multiple organic (1 and 5 ppm of C) and Cl- (>0.01 M) concentrations for both acetic and formic acids. Independent experiments with pyruvic acid and different halogen salts are consistent with the proposed mechanism. Our findings provide a plausible mechanistic explanation for Cl- interference in WCO-derived TOC measurements of environmental samples for which halogenated salts are present. A plausible mechanism provides a more complete understanding of how and why the TOC is biased low in environmental aquatic samples from saline environments when WCO is employed.

Stepwise extraction of zinc, indium and lead from secondary zinc oxide dusts experimental study

Secondary zinc oxide dust is rich in high-grade metals such as Zn, In, Pb, and Ga, and in the face of the depletion of ore resources at home and abroad, it is of great significance to seek an efficient process to realize the full resource recovery of valuable metals in secondary zinc oxide dust. In this study, on the basis of the thermodynamic analysis of the wet treatment process, three wet treatment methods, namely “low acid leaching”, “high acid leaching” and “chlorination leaching”, were used to explore the suitable parameters for stepwise extraction of Zn, In and Pb metals. The results showed that the three wet treatment methods could effectively extract the corresponding main elements, and the optimal leaching rates of Zn, In and Pb were 73, 90 and 94%, respectively. Thermodynamic analysis shows that under ideal conditions, the “cascade separation” of some or all metals can be theoretically achieved by using a suitable leaching solvent for zinc oxide dust. The concentration of sulfuric acid, the ratio of liquid solid volume to mass and temperature had great effects on the leaching rate of Zn and In, and the leaching rate of Zn and In also increased with the increase of the values of the three experimental parameters, which was positively correlated. The leaching rate of Pb will increase with the increase of sulfuric acid concentration, but when the pH of the solution system is < 2, Pb will form PbSO4 precipitate, which inhibits the leaching ability of Pb. In the chlorinated leaching system with “ammonium chloride + hydrochloric acid” as the leaching solvent, the excess Cl− and Pb2+ fully coordinated to promote the efficient leaching of Pb metal, and the initial pH value of the solution had a great influence on the Leaching Rate of Pb. The multi-stage combined wet treatment process is an effective solution to realize the full quantitative recovery of valuable elements in Secondary zinc oxide dust, In this paper, the suitable process conditions for stepwise extraction of Zn, In and Pb metals were obtained through wet treatment experiments, and the cascade separation of metals in zinc oxide dust was preliminarily realized, which provided an important idea for the efficient utilization of metallurgical dust and sludge solid wastes, and at the same time provided theoretical support for the industrial practice of recycling valuable elements in metallurgical dust.

Investigating the environmental impacts of lithium-oxygen battery cathode production: A comprehensive assessment of the effects associated with oxygen cathode manufacturing

Lithium-oxygen batteries offer remarkably high energy density compared to current lithium-ion batteries. The key to their electrochemical performance lies in the processes occurring at the air cathode. However, the complexity of these reactions, coupled with the by-products generated during discharge, can make the reaction process slow or impede their efficiency. This study evaluates the environmental impact of high-efficiency lithium-oxygen batteries cathodes, including titanium oxide composites, graphene-based composites and activated carbon-based composites, through a life cycle assessment across 18 impact categories using a cradle-to-gate approach with a functional unit of 25 kWh. Results show that active material production was the largest contributor to environmental impact, particularly Global Warming Potential. Among the evaluated cathodes, reduced graphene oxide/α-mnaganese oxide/palladium (rGO/α-MnO2/Pd) demonstrated the highest environmental impact, with a global warming potential of 1130.71 kg carbon dioxide from active material production, due to its energy-intensive synthesis and the use of chemicals like sulfuric acid, sodium borohydride, hydrochloric acid, and hydrogen peroxide. Additionally, the rGO/α-MnO2/Pd cathode had the highest Human Toxicity Potential and Ozone Depletion Potential. Batteries with graphene-based cathodes achieved a specific capacity of 7500 mAh.g-1, underscoring their performance potential while highlighting the need for more sustainable cathode manufacturing methods. These findings emphasize the environmental considerations necessary for large-scale lithium-oxygen batteries implementation.

Precisely controlled electrostatically sprayed sodium alginate/carboxymethyl chitosan hydrogel microbeads as super-adsorbent for adsorption of cationic dye.

In this pioneering study, electrostatic spraying (ES) technology with high voltages is proposed to reduce the size of hydrogel microbeads further, aiming to enhance the adsorption rate of cationic methylene blue (MB) dye. The increased voltages, ranging from 0.0 to 13.0 kV, further decreased the size of electrostatically sprayed hydrogel microbeads crosslinked by hydrogen bonds between sodium alginate (SA) and carboxymethyl chitosan (CMCS) in hydrochloric acid. The size of SA/CMCS hydrogel microbeads was successfully reduced from 2000 ± 121 μm (SC-2000) to 400 ± 15 μm (SC-400). Notably, SC-400 exhibits the highest maximum adsorption capacity (qm) and rate constant (k2) at 840.3 mg/g and 0.0598 g/mg/min, respectively, at pH 9.0 and a temperature of 25 °C in the absence of ionic compounds, which is three times higher than that of SC-2000, due to their high specific surface area and pore volume. Through a series of adsorption studies and characterization analyses, SA/CMCS hydrogel microbeads displayed heterogeneous adsorption behaviors towards MB dye through electrostatic interactions between the deprotonated carboxylic groups and cationic MB molecules, where MB adsorption efficiency could be significantly influenced by pH and ionic strength. These findings suggest that ES technology is effective in synthesizing smaller SA/CMCS hydrogel microbeads with enhanced MB removal rates and stable adsorption capacities and their applications could be further explored for removing other organic dyes and toxic metals in subsequent research studies.

The effects of sample preparation on the interpretation of pyrolysis-based organic matter analysis in immature oil shale

Oil shale as well as shale oil and shale gas are significant energy resources with huge reserves present in different parts of the world. Various geochemical proxies have been applied to assess the petroleum potential of oil shales with samples pre-treated in various ways, e.g. as whole rock or demineralized sample or as solvent extracted rock/kerogen. In this respect, it is important to understand and quantify, how achieved geochemical parameters are influenced by pre-treatment. In this study, a systematic comparison is presented based on a study on i) whole rock, ii) extracted whole rock, iii) kerogen concentrate, and iv) extracted kerogen concentrate obtained after solvent extraction of demineralized shales. In total, seven immature, organic matter-rich samples from the Miocene lacustrine sediments of the Nördlinger Ries impact crater, Germany, were pretreated in this way leading to overall 28 samples. A set of elemental analysis (C, H, N), Rock-Eval pyrolysis, and Curie Point-pyrolysis–gas chromatography–mass spectrometry measurements were performed on these pretreated samples. Mineral matter removal leads to significant increase of total organic carbon, but also thermally evaporable and pyrolytically cracked organic matter (Rock-Eval S1 and S2 peaks). To some extent, labile organic matter represented in the original S2 peak can be destructed by mineral removal with hydrochloric and hydrofluoric acid, as shown by elevated values of PI [S1/(S1 + S2)] after demineralization. The organic matter type tends to be more petroleum-prone with raised hydrogen index (HI) and aliphaticity values after demineralization, while Rock-Eval Tmax values commonly applied as parameters for thermal maturity tend to decrease, though not for all samples.Reduced TOC, S1, S2 and PI values of extracted samples suggest that both thermally evaporable and additionally some non-evaporable but soluble organic matter hidden in the original S2 peak can be lost after solvent extraction. Increased values of HI, H/C and N/C of extracted samples indicate more oil-prone organic matter types than unextracted samples. Typical maturity-related parameters such as aliphaticity and Rock-Eval Tmax decrease. Smectite and zeolites, which are abundant in the samples, are suggested to protect organic matter to some extent against solvent extraction, influencing a variety of geochemical proxies and the occurrence of metal cation-containing minerals. Zeolite invigorates the protection effect.

Metal ion-induced multi-layer coatings improves gastrointestinal resistance of Lactiplantibacillus plantarum and biosafety evaluation

Probiotics provide numerous health benefits; however, their low survival rate in gastric acid and short retention time in the intestine are major obstacles to their effective utilization. Here, a simple yet effective novel probiotic multilayer coating consisting of Fe3+-protocatechuic acid (PCA) crosslinked network and Ca2+-induced sodium alginate (SA) for arming Lactiplantibacillus plantarum (LP) was developed. The Fe3+-PCA and SA coating process did not affect the normal growth of probiotics. Electron microscopy experiments confirmed the feasibility of this coating strategy. In vitro simulations of gastric acid and bile salt environments demonstrated that SA-PCA coating could enhance probiotics' resistance to gastrointestinal digestion and protect against damage from ethanol and antibiotics. In vivo survival experiments further showed that SA-PCA coating improved the probiotic survival rates. Biosafety experiments indicated that this coating strategy exhibited good biosafety. This study introduces a novel conservation strategy in probiotic delivery, providing effective protection for probiotics and offering theoretical references for developing innovative approaches to alleviate related diseases.

Efficient one-pot tandem C-C formation reaction catalyzed by a multi-functionalized polyacrylonitrile fiber catalyst

A simple and straightforward method has been proposed in this work to construct a multi-functionalized polyacrylonitrile fiber catalyst containing carboxylic acid, tertiary amine, and quaternary ammonium salt to enable series one-pot C-C bond formation in water. The fiber catalyst was prepared from polyacrylonitrile fiber using a two-step method and characterized using various detection techniques. Furthermore, the activity of multi-functional synergistic catalysts can be controlled by adjusting the ratio of acid and base. It is noteworthy that the polyacrylonitrile fiber catalyst with an acid-base ratio of 3:1 (PANF-ABNCl3/1) exhibited superior catalytic activity and high yield in a variety of C-C generation reactions. Additionally, the PANF-ABNCl3/1 catalyst demonstrated exceptional recyclability (at least 10 times) and performed well in scale-up (7.4g, 96%) and continuous flow experiments (can be used continuously for 7 × 24h) using kettle and tubular fixed bed reactor respectively. These findings suggest that the PANF-ABNCl3/1 catalyst holds promise for industrialization.