Chelating Effect Research Articles

Copper as the driver of the lncRNA-TCONS-6251/miR-novel-100/TC2N axis: Unraveling ferroptosis in duck kidney

Ferroptosis is an iron-dependent form of oxidative cell death. Competitive endogenous RNAs diminish the inhibitory impact of microRNAs on other transcripts by chelating effects, which affects ferroptosis and reactive oxygen species (ROS) levels. However, the role of ferroptosis in excessive copper (Cu)-induced renal injury via the ceRNA axis has not been fully illustrated yet. Herein, we found that Cu induced ferroptosis in duck renal tubular epithelial cells, as indicated by the increase in intracellular iron levels and lipid peroxidation, upregulation of PTGS2 and ACSL4 levels, reduced GPX4 and GSH levels. In addition, knockdown miR-novel-100 could effectively decreased ferroptosis induced by Cu. Overexpression of miR-novel-100 or TC2N knockdown resulted in the stimulation of ROS and the upregulation of ferroptosis indicators. However, butylated hydroxyanisole (BHA) decreased the stimulation of ROS and the ferroptosis effect caused by miR-novel-100 overexpression. In conclusion, Cu induced ferroptosis by activating the lncRNA-TCONS-6251/miR-novel-100/TC2N axis to cause ROS accumulation.

Induction of Ca2+ signaling and cytotoxic responses of human lung fibroblasts upon an antihistamine drug oxatomide treatment and evaluating the protective effects of Ca2+ chelating.

Oxatomide, an antihistamine drug of the diphenylmethylpiperazine family, has anti-inflammatory effects in airway disease. Because oxatomide was shown to cause diverse physiological responses in several cell models, the impact of oxatomide on Ca2+ signaling and its related physiological effects has not been explored in IMR-90 human fetal lung fibroblasts. This study assessed the effect of oxatomide on cell viability and intracellular free Ca2+ concentrations ([Ca2+]i) and examined whether oxatomide-induced cytotoxicity through Ca2+ signaling in IMR-90 cells. Cell viability was measured by the cell proliferation reagent (WST-1). [Ca2+]i was measured by the Ca2+-sensitive fluorescent dye fura-2. Oxatomide (10-40 μM) concentration dependently reduced cell viability and induced [Ca2+]i rises in IMR-90 cells. This cytotoxic effect was reversed by chelation of cytosolic Ca2+ with BAPTA-AM. In terms of Ca2+ signaling, oxatomide-caused Ca2+ entry was inhibited by modulators of store-operated Ca2+ channels (2-APB and SKF96365) and protein kinase C (PKC) inhibitor (GF109203X). Furthermore, oxatomide-induced Ca2+ influx was confirmed by Mn2+-induced quench of fura-2 fluorescence. In a Ca2+-free medium, preincubation with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin inhibited oxatomide-evoked [Ca2+]i rises. Conversely, treatment with oxatomide abolished thapsigargin-induced [Ca2+]i rises. Inhibition of phospholipase C (PLC) with U73122 also inhibited oxatomide-caused [Ca2+]i rises. In IMR-90 cells, oxatomide-induced cytotoxicity by preceding [Ca2+]i rises involving PKC-sensitive store-operated Ca2+ entry and PLC-dependent Ca2+ release from the endoplasmic reticulum. BAPTA-AM, with its Ca2+ chelating effects, may be a potential compound for preventing oxatomide-induced cytotoxicity.

Effect and Mechanism of Zirconium Crosslinker on Retarding Degradation of HPAM/PEI Gel System in Medium-Salinity Reservoirs

Summary The objective of this paper is to investigate the effect of the addition of zirconium crosslinker on retarding the degradation of the partially hydrolyzed polyacrylamide/polyethyleneimine (HPAM/PEI) gel system. Dehydration and degradation under salinity conditions pose serious challenges to the effectiveness of the HPAM/PEI system used for water control treatment in heterogeneous reservoirs. In this study, rheological tests, Fourier transform infrared (FTIR) spectroscopy, and 13C nuclear magnetic resonance (NMR) spectroscopy are used to elucidate the characteristics and mechanisms of dehydration and degradation of HPAM/PEI gel in medium-salinity conditions. The effects of three types of zirconium crosslinkers on the gelation performance of the HPAM/PEI system are evaluated. Furthermore, the mechanism by which an organic zirconium complex (ZrOr complex) with triethanolamine (TEA) and lactic acid (LA) as ligands improves the stability of the HPAM/PEI system under medium-salinity conditions is revealed. The results indicate that ZrOr complex notably retards the degradation of the HPAM/PEI system under medium-salinity conditions (50 g/L) for more than 60 days while improving its gel strength. TEA and LA as ligands have a positive effect on crosslinking of HPAM with the organic Zr4+ complex by modulating the availability of Zr4+ and the homogeneity of the crosslinking reaction. Specifically, our data suggest that TEA stabilized Zr4+ and retarded its release through its chelating effect, while LA improved the efficiency and effectiveness of the crosslinking reaction by increasing the solubility of Zr4+ and providing additional carboxyl groups. The synergistic effect of the two ligands significantly improved the properties of the final crosslinked product. Evidence from FTIR, 13C NMR, and microstructural tests supports the conclusion that the retardation of degradation and enhancement of gelation performance in the HPAM/PEI system by ZrOr complex are associated with its crosslinking with carboxyl groups produced by HPAM hydrolysis, leading to the formation of a more uniform and compact network structure. A field trial conducted in the Beiyao Block demonstrated the potential of the ZrOr complex to extend the treatment lifetime of the HPAM/PEI gel system in medium-salinity reservoirs.

The effect of combinations of a glyphosate-based herbicide with various clinically used antibiotics on phenotypic traits of Gram-negative species from the ESKAPEE group

The emission of glyphosate and antibiotic residues from human activities threatens the diversity and functioning of the microbial community. This study examines the impact of a glyphosate-based herbicide (GBH) and common antibiotics on Gram-negative bacteria within the ESKAPEE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli). Ten strains, including type and multidrug-resistant strains for each species were analysed and eight antibiotics (cefotaxime, meropenem, aztreonam, ciprofloxacin, gentamicin, tigecycline, sulfamethoxazole-trimethoprim, and colistin) were combined with the GBH. While most combinations yielded additive or indifferent effects in 70 associations, antagonistic effects were observed with ciprofloxacin and gentamicin in five strains. GBH notably decreased the minimum inhibitory concentration of colistin in eight strains and displayed synergistic activity with meropenem against metallo-β-lactamase (MBL)-producing strains. Investigation into the effect of GBH properties on outer membrane permeability involved exposing strains to a combination of this GBH and vancomycin. Results indicated that GBH rendered strains sensitive to vancomycin, which is typically ineffective against Gram-negative bacteria. Furthermore, we examined the impact of GBH in combination with three carbapenem agents on 14 strains exhibiting varying carbapenem-resistance mechanisms to assess its effect on carbapenemase activity. The GBH efficiently inhibited MBL activity, demonstrating similar effects to EDTA (ethylenediaminetetraacetic acid). Chelating effect of GBH may have multifaceted impacts on bacterial cells, potentially by increasing outer membrane permeability and inactivating metalloenzyme activity.

Assessment of Nutraceuticals Potentials of Protein Isolates from Seed Coat of Four Melon Species

Recently, there has been more attention on the bioactivity of phytochemicals and other metabolites in agro-food by-products for the management of oxidative stress–related conditions. Hence, the objective of this paper is to assess the nutraceuticals potential by investigating antioxidant and α-amylase inhibitory potentials of seed coat protein isolates from four melon species namely: Citrullus colocynthis, Citrullus mucosospermus, Cucumeropsis mannii and Lagenaria siceraria using appropriate standard methods. At highest concentration, Lagenaria siceraria had the strongest free radical scavenging activity (38% inhibition). The strongest chelating effect was exhibited by C. mannii (IC50 = 0.59 ± 0.08 mg/ml), which also showed highest ferric reducing potential at all concentrations. At 0.05 mg/ml, C. colocynthis, C. mucosospermus, C. mannii, and L. siceraria seed coat protein extracts inhibited alpha-amylase activity by 43.2%, 16.76%, 2.6% and 22.3%, respectively, and inhibition of 60.9%, 28.6%, 38.3% and 29.5% were recorded for the seed protein extracts respectively, at 0.5 mg/ml. In conclusion, the various melon seed coat protein isolates showed appreciable levels of antioxidants and possessed inhibitory activity against α-amylase. Hence, the seed coats of the four melon varieties assessed in this study are promising potential sources of antioxidants for the supplementary treatment of oxidative stress–induced conditions.

Preparation of imprinted cryogels of cellulose cross-linked ionic liquids for selective separation of Gd(III) from rare earth leachate

The development of high technology has elevated industry’s dependence on rare earth resources. The hydrometallurgical process is widely used for the separation of rare earth elements (REEs) from rare earth ores, producing acidic leachate with trace amounts of REEs. Recovery of REEs from rare earth leachate not only mitigates the negative impact of leachate on the environment, but also contributes to the realization of sustainable resource utilization. In this study, two novel imprinted cryogel adsorbents, methyltrioctylammonium chloride-derivative carboxymethylated cellulose nanocrystal imprinted cryogel (LR-ICMC) and ethylmethylimidazolium bromide-derivative carboxymethylated cellulose nanocrystal imprinted cryogel (LM-ICMC), were constructed by using carboxymethylated modified cellulose nanocrystals as a backbone structure, and successfully branched ionic liquids (ILs) methyltrioctylammonium chloride-derivative and ethylmethylimidazolium bromide-derivative, respectively, for the separation of gadolinium ions (Gd(III)) from rare earth leachate. Firstly, SEM and TEM results showed that the incorporation of ILs retained part of the pore structure of carboxymethylated cellulose nanocrystals (CMCNCs). BET and TG results illustrated that the incorporation of ILs effectively increased the specific surface area and thermal stability of LR-ICMC and LM-ICMC. FT-IR and XPS results showed that LR-ICMC and LM-ICMC could adsorb Gd(III) by electrostatic and chelating effects. Secondly, adsorption isotherm experiments demonstrated the adsorption capacities of 66.880 mg/g and 75.895 mg/g for LR-ICMC and LM-ICMC, respectively; adsorption kinetic experiments demonstrated the ability of LR-ICMC and LM-ICMC to rapidly adsorb 85.152 % and 87.989 % of the maximum adsorption capacity, respectively, within the initial first 40 min. Finally, cycling experiments demonstrated the advantages of LR-ICMC and LM-ICMC in reuse, maintaining 89.245 % and 90.734 % of the original performance after five adsorption–desorption cycles, respectively. Based on these results, LR-ICMC and LM-ICMC were demonstrated to be highly efficient and reusable adsorbents for selective recovery of Gd(III) from rare earth leachate. This study deepens the application of ILs in solid-phase adsorbents and highlights the great potential of LR-ICMC and LM-ICMC in the field of REEs recovery.

A novel high corrosion-resistant and superhydrophobic MAO-30/PA/VTES composite coating on Cu[sbnd]15Fe alloy for long-term corrosion protection

The copper (Cu) alloys are prone to severe corrosion in marine environments. In this work, we successfully develop a novel high corrosion-resistant and superhydrophobic MAO-30/PA/VTES composite coating on Cu15Fe alloy for long-term corrosion protection. The composite coating, with a corrosion rate of 0.00001 mm/y and a water contact angle of 152.7°, presents significant advantages over most Cu alloys modification methods to date. Benefiting from the modification with phytic acid (PA) and vinyltriethoxysilane (VTES), the corrosion current density of the composite coating remains 2.14 × 10−10 A·cm−2 even after 168 h of immersion in 0.6 M NaCl, which is four orders of magnitude lower than Cu15Fe substrate (5.68 × 10−6 A·cm−2). The exceptional long-term corrosion resistance of the composite coating is attributed to the physical barrier effect of the micro-arc oxidation (MAO) layer, the superhydrophobic characteristics and sealing effect of the PA/VTES film layer, and the chelating effect of the phytic acid. Developing the composite coating introduces a new approach to protecting Cu alloys from corrosion in marine environments.

Fire-resistant and thermal-insulating alginate aerogel with intelligent bionic armor for exceptional mechanical and fire early-warning performance

Intelligent bio-based aerogels have attracted increasing attention in several key areas due to their unique porous structure and sustainability, but they suffer from poor fire safety, strength, and durability under harsh conditions. Here, we prepared sodium alginate/hydroxyapatite/graphene oxide (SA@HAP@GO) aerogel by in-situ growth and directional assembly technology, and an intelligent “bionic armor” was put on the surface of SA aerogel. It not only endows aerogel with high strength (2.3 MPa) and long-time water resistance (30 days) but also maintains the lightweight (0.039 g cm−3) and thermal insulation properties (0.03537 W m-1K−1) of original aerogel. Under fire conditions, the compact physical barrier makes aerogel obtain the excellent fire-resistant stability and fire-safety performance. Besides, the directional assembly of GO and the chelating effect of Ca2+ on aerogel surface promote the formation of a three-dimensional electron transport network during reduction process, thus achieving a fast and long-lasting fire early-warning response (1.95 s). The corresponding mechanism was demonstrated by molecular theoretical calculation and experiments. This multifunctional aerogel provides a new way for sustainable and high-performance thermal-insulation materials and shows a wide application in energy security.

The mitigating effects and mechanisms of Bacillus cereus on chronic cadmium poisoning in Litopenaeus vannamei based on histopathological, transcriptomic, and metabolomic analyses

Shrimp are non-negligible victims of cadmium (Cd) contamination, and there is still a lack of strategies for mitigating Cd toxicity in shrimp. Bacillus cereus, with its significant heavy metal (HM) tolerance and chelating effects, is a representative beneficial bacterium to be investigated for mitigating the toxicity of Cd exposure. This study revealed the effects and potential mechanisms of B. cereus in mitigating chronic Cd toxicity in shrimp by analyzing growth performance, hepatopancreatic Cd accumulation, pathology, as well as comprehensive hepatopancreatic transcriptomics and metabolomics in Litopenaeus vannamei. The results showed that shrimp's growth inhibition, hepatopancreatic Cd accumulation and physiological structure damage in B. cereus+chronic Cd group were effectively alleviated compared with the chronic Cd treatment group. The pathways related to amino acid metabolism, glycolipid metabolism, immune response, and antioxidant stress were significantly activated in the B. cereus+chronic Cd group, including glycolysis, pentose phosphate pathway, oxidative phosphorylation, biosynthesis of amino acids, and biosynthesis of unsaturated fatty acids pathways. The key differentially expressed genes (e.g., macrophage migration inhibitory factor, glycine cleavage system H protein, glycine dehydrogenase, phosphoglucomutase-2, asparaginase, ATP synthase subunit, cytochrome c, and 4-hydroxyphenylpyruvate dioxygenase) and metabolites (e.g., L-leucine, D-ribose, gluconic acid, 6-Phosphogluconic acid, sedoheptulose 7-phosphate, 1-Kestose, glyceric acid, arachidic acid, prostaglandins, 12-Keto-tetrahydro-leukotriene B4, and gamma-glutamylcysteine) associated with the above pathways were significantly altered. This study demonstrated that B. cereus is an effective mitigator for the treatment of chronic Cd poisoning in shrimp. B. cereus may play a role in alleviating the toxicity of Cd by enhancing the antioxidant performance, immune defense ability, metabolic stability, and energy demand regulation of shrimp. The study provides reference materials for the study of B. cereus in alleviating Cd toxicity of shrimp and broadens the application of probiotics in treating HM toxicity.

(Invited) Highly Water-Soluble Fullerene Derivatives for Durable Polymer Electrolyte Membrane Fuel Cells

Recently, the focus of proton-exchange membrane fuel cell (PEMFC) applications has shifted from fuel cell vehicles (FCVs) to heavy-duty vehicles (HDVs), necessitating enhanced fuel cell durability. The degradation of carbon-supported metal nanoparticle catalysts and electrolyte membranes are the primary factors responsible for fuel cell durability. Particularly in the context of HDVs, augmenting the chemical stability of electrolyte membranes, such as Nafion, stands as a crucial factor in improving fuel cell lifetime. The degradation mechanism of Nafion is believed to involve the cleavage of polymer chains by OH∙ radicals, formed by crossover hydrogen and crossover oxygen in the presence of trace transition metal ions. A common strategy to mitigate Nafion's chemical degradation involves adding radical quenchers like cerium ion (Ce+) to Nafion. However, Ce+ may migrate out of Nafion during fuel cell operation, leading to a decline in its highly efficient radical quenching ability over extended operational periods.In this study, we demonstrate that a fullerene-derived radical quencher with multiple hydroxy groups significantly contributes to enhancing the durability of Nafion. Our approach involves synthesizing fullerene derivatives with various kind of hydroxy and functional groups for remarkable water solubility to realize their homogeneous dispersion within the Nafion membrane. The abundant functional groups also aid in improving proton conductivity. Moreover, the chelating effect of the spherically distributed functional groups immobilizes themselves, preventing any observed leakage from the Nafion membrane. These fullerene-derivative radical quenchers effectively enhance fuel cell durability and hold promise for future applications in HDVs.This study was supported by the New Energy and Industrial Technology Development Organization (NEDO), Japan (JPNP20003).

Synthesis and Biological Evaluation of 3-Alkyl(Aryl)-4-(4-methylthio-benzylideneamino)-4,5-dihidro-1H-1,2,4-triazol-5-one Derivatives

In the present study, 3-alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (3c, f, e) reacted with 4-methylthiobenzaldehyde to afford 3-alkyl(aryl)-4-(4-methylthio-benzylideneamino)-4,5-dihidro-1H-1,2,4-triazol-5-ones (4c, f, e). The structures of three new compounds were established from the elemental analysis, IR, 1H NMR, and 13C NMR spectral data. The newly synthesized and recently synthesized 3-alkyl(aryl)-4-(4-methylthiobenzylideneamino)-4,5-dihidro-1H-1,2,4-triazol-5-one derivatives were analyzed using three methods for antioxidant activities. Compound 4a showed the best activity for the metal chelating effect. Furthermore, the compounds' antimicrobial activity was screened.

Phosphate chelation over calcium impacts yeast growth and lipid production from short-chain fatty acids-rich media

Some oleaginous yeasts have the ability to produce microbial oils from alternative carbon sources, such as short-chain fatty acids (SCFAs). Nevertheless, there is still a lack of information about the possible effects that media nutrients have on yeast metabolisms when using SCFAs. For instance, inorganic phosphate (PO43-) has been reported to promote yeast growth in literature but its chelating effect over other elements such as calcium (Ca2+) is often not considered in fermentation processes while limitation of nitrogen is probably the most studied. Attending at the need to better understand the role of PO43-, this work assessed the lipid production capacity of Yarrowia lipolytica ACA DC 50109, both in synthetic and real SCFAs-rich media, at different SCFAs concentrations and PO43-:Ca2+ ratios. Reducing PO43-:Ca2+ ratio was identified to be an important factor to improve yeast growth, reaching the highest lipid content (52.7 ± 0.9 % w/w) and lipid yield (0.31 ± 0.01 w/w) in media without PO43-. These results demonstrated the importance of Ca2+ availability in the medium and nutrients interactions in yeast growth that are often underestimated.

Phytic acid-doped polypyrrole/graphene oxide nanofillers for the preparation of self-healing anticorrosion coatings with the synergistic physical barrier, passivation and chelating effect

The corrosion protection of organic coatings for metal substrates is generally limited because of the unavoidable coating micropores and cracks, even the coating anticorrosion function will lose when it is damaged. Although the addition of nanofillers into the organic coating matrix can effectively address the above issues, it is challenging to facilely and wholesale construct surface-modified nanofillers with synergistic anticorrosion ability of physical barrier, passivation and chelating effect. In this study, we develop a simple one-pot approach for preparing polypyrrole (PPy) modified graphene oxide (GO) nanofillers with the doping of phytic acid (Ph) (namely GO-PPy@Ph nanoparticles) and then incorporating them into epoxy resin (EP) coating system to form the anticorrosion nanocomposite coatings. The research results display that the GO-PPy@Ph nanoparticles can uniformly disperse in the EP coatings to improve their anti-penetrant ability against corrosive media. And the introduction of GO-PPy@Ph nanoparticles effectively enhances the coating adhesion strength and mechanical performance. Moreover, the anticorrosion tests show that the impedance modulus at 0.01 Hz of GO-PPy@Ph coating after 60-day immersion in 3.5 wt% NaCl solution remains at about 1010 Ω cm2. The dramatical anticorrosive performance of the GO-PPy@Ph coating with self-healing performance is attributed to the synergistic protection of impermeable GO-PPy@Ph nanosheets, passivation function of PPy and metal chelation effect of Ph. This study provides an effective and universal avenue to construct multifunctional nanofillers with the synergistic anticorrosion of high physical barrier, passivation and metal chelating effects for developing anticorrosive nanocomposite coatings with high performances, which have highly attractive potential in the commercialization applications of metal corrosion protection.

Highly Crystalline Multivariate Prussian Blue Analogs via Equilibrium Chelation Strategy for Stable and Fast Charging Sodium-Ion Batteries.

Prussian blue analogs (PBAs) have been widely recognized as superior cathode materials for sodium-ion batteries (SIBs) owing to numerous merits. However, originating from the rapid crystal growth, PBAs still suffer from considerable vacancy defects and interstitial water, making the preparation of long-cycle-life PBAs the greatest challenge for its practical application. Herein, a novel equilibrium chelation strategy is first proposed to synthesize a high crystallinity (94.7%) PBAs, which is realized by modulating the chelating potency of strong chelating agents via "acid effect" to achieve a moderate chelating effect, forcefully breaking through the bottleneck of poor cyclic stability for PBAs cathodes. Impressively, the as-prepared highly crystalline PBAs represent an unprecedented level of electrochemical performance including ultra-long lifespan (10000 cycles with 86.32% capacity maintenance at 6Ag-1), excellent rate capability (82.0mAhg-1 at 6Ag-1). Meanwhile, by pairing with commercial hard carbon, the as-prepared PBAs-based SIBs exhibit high energy density (350Whkg-1) and excellent capacity retention (82.4% after 1500 cycles), highlighting its promising potential for large-scale energy storage applications.

Elucidating the interaction mechanisms between polyacrylic acid and Alloy 800 oxide films under pressurized water reactor steam generator conditions

The interaction mechanisms between polyacrylic acid (PAA) and Alloy 800 were investigated. Alloy 800 formed a bilayer oxide structure in all conditions, with an outer layer of Fe-rich spinel and α-Ni(OH)2 and a Cr-rich inner layer. The chelating effect of PAA on Fe ions reduced the presence of Fe-rich spinel in the outer layer and increased the Cr content in the inner layer. However, thermal degradation of PAA (≥ 500 ppb) promoted dissolution of Cr in the initial inner layer, increasing the initial corrosion rate. The optimal PAA dosage in steam generators is determined to be approximately 250 ppb.

Influence of humic substances on growth performance and blood serum parameters in fattening turkeys

The present study was conducted to evaluate the effect of humic substances on performance and selected blood biochemical parameters in turkeys. A total of twenty 6-week-old turkey hybrids (Big 6) were divided into two groups. The first group of turkeys was fed the basal diet without any supplementation of humic substances as a control group. The second group was fed the basal diet supplemented with 5 g of humic substances per kg of diet. The study lasted 35 days, until the 11th week of age of the turkeys. The addition of humic substances had no effect on the live body weight, body weight gain, feed intake, feed conversion ratio, or growth rate of turkeys. Similarly, the monitored blood biochemical parameters, except for the levels of P, Mg, and Na, were not significantly affected by the addition of humic substances. The addition of humic substances led to a significant decrease in the concentration of P (p˂0.05), Mg (p˂0.05), and Na (p˂0.01) in the blood serum of turkeys. It was concluded that the addition of humic substances may lead to a reduction of some mineral substances in the blood of animals, which may be due to their chelating effects. This may indicate a reduced availability of some biologically important minerals for the body, which could subsequently manifest itself in some health issues and a decrease in animal production. During the duration of our study, there were no signs of disturbance in the health of the animals. In view of the achieved results, further studies will be necessary to determine the appropriate concentration and duration of administration of the monitored preparation and to evaluate its influence on the availability of nutrients and feed conversion and its possible use as a safe non-antibiotic growth stimulator in turkey nutrition.

Fabrication of N and S co-doped lignin-based porous carbon aerogels loaded with FeCo alloys and their application to oxygen evolution and reduction reactions in Zn-air batteries

Zn-air batteries are a highly promising clean energy sustainable conversion technology, and the design of dual-function electrocatalysts with excellent activity and stability is crucial for their development. In this work, FeCo alloy loaded biomass-based N and S co-doped carbon aerogels (FeCo@NS-LCA) were fabricated from chitosan and lignosulfonate-metal chelates via liquid nitrogen pre-frozen synergistic high-temperature carbonization with application in electrocatalytic reactions. The abundant oxygen-containing functional groups on lignosulfonates have a chelating effect on metal ions, which can avoid the aggregation of metal nanoparticles during carbonation and catalysis, facilitating the construction of a nanoconfinement catalytic system with biomass carbon as the domain-limiting body and FeCo nanoparticles as the active sites. FeCo@NS-LCA exhibited catalytic activity (E1/2 = 0.87 V, JL = 5.7 mA cm−2) comparable to the commercial Pt/C in the oxygen reduction reaction (ORR), excellent resistance to methanol toxicity and stability. Meanwhile, the overpotential of oxygen evolution reaction (OER) was 324 mV, close to that of commercial RuO2 catalysts (351 mV). This study utilizes the coordination action of lignosulfonate to provide a novel and environmentally friendly method for the preparation of confined nano-catalysts and provides a new perspective for the high-value utilization of biomass resources.

Bipolar membrane assistant landfill leachate coagulation by bauxite tailings with oxalic acid

In this study, bauxite tailings were innovatively employed as the coagulant resource in the treatment of nanofiltration concentrated landfill leachate (NCLL) via bipolar membrane electrodialysis (BMED). The employment of H2C2O4 as the leaching acid, in lieu of HNO3, not only promoted the leaching of metal ions but also minimized the competitive migration of free H+, attributable to its chelating effect. The COD removal increased from about 40.4 % to about 49.9 %, while the energy consumption (EC) decreased to about 0.05 kWh/g COD when the acid is replaced by H2C2O4. An optimal dosage of bauxite tailing is crucial for effective COD removal. An increase in the initial concentration of H2C2O4 benefits metal leaching, while, an excessive concentration thereof augments the competition of H+ ions, thereby impeding the coagulation process. Furthermore, the current density exerted a notable impact on both COD removal and EC, with an optimal density identified at 5 mA/cm2. Connecting more treatment units still maintains COD removal efficiency at approximately 50 %, with a significant reduction in EC of about 24 %, necessitating only 0.038 kWh/g COD. Humic-like and fulvic-like acids are efficiently coagulated, which represent the principal biorefractory substances in NCLL. Consequently, this research delineates a novel approach for the utilization of bauxite tailings and the treatment of NCLL.

Covalent organic framework@cellulose nanofibrils@carboxymethyl cellulose composite hydrogel beads for the removal of nickel ions from aqueous solutions

A novel adsorbent, covalent organic framework (COF)@cellulose nanofibrils (CNF) @carboxymethyl cellulose (CMC) composite hydrogel bead (CCCHB), was prepared for Ni2+ removal from aqueous solutions. The imine COF provides the main active sites for adsorption. CNF is used as the carrier for grafting COF to improve the dispersion of COF and the reinforcing material. CMC is used as the hydrogel matrix to facilitate easy recycling. The equilibrium adsorption capacity (qe) of the CCCHB is vastly influenced by the mass ratio of COF@CNF/CMC. The optimized mass ratio of COF@CNF/CMC is 0.050/1 (g/g). The maximum adsorption is reached at pH=6. The qe of Ni2+ increases with a rise in initial concentration of the solution. Based on Langmuir isotherms, the maximum adsorption capacity of CCCHB is 289.50 mg/g. The adsorption of Ni2+ complies with the pseudo-second-order kinetic model. The CCCHBs still maintain preferable adsorption properties after the seventh cycle of adsorption–desorption. The Ni2+adsorption of the CCCHB is mainly attributed to the chelating effect and electrostatic interaction.

Bentonite as an arsenic and lead adsorbent in the bovine digestive tract: an in vitro study

Objective. To determine the recommended dose of bentonite as a chelator of arsenic (As) and lead (Pb) in the rumen, abomasal and duodenal environment by means of an in vitro system, considering the variables of ruminal fermentation and the adsorbent effect of As and Pb. Materials and Methods. Vials were prepared with 50 mL of anaerobic medium and 0.5 g of alfalfa as substrate. The culture media were added with 1.01 and 1.95 ppm of As and Pb, respectively. The treatments consisted of different levels of bentonite (B) added to the medium, B-0%, B-1.5%, B-3.0% and B-4.5%. The media were incubated for 24 h, and pH, volatile fatty acid (VFA) and N-NH3 production, in vitro DM digestibility (IVDMD) and chelating effect of bentonite were measured, simulating rumen, abomasum and duodenum conditions. A completely randomised design and orthogonal contrasts were used. Results. Bentonite did not modify the pH (p > 0.05) and the molar proportion of VFAs, but the total VFA concentration presented a negative linear effect with increasing bentonite levels. Likewise, the N-NH3 level decreased (p < 0.05) with increasing inclusion levels of bentonite. The IVDMD was reduced with B-3% and B-4.5% (52.36b and 49.74b%) in comparison to B-0% and B-1.5% (62.30a and 61.98a%). Treatments B-1.5% and B-4.5% improved (p < 0.05) As and Pb adsorption in the rumen, abomasal and duodenal environments. Conclusions. The recommended level of bentonite as chelator of As and Pb is 1.5%; doses of 4.5% affect IVDMD and, consequently, animal productivity.