Recent advances in virulence of a broad host range plant pathogen Sclerotinia sclerotiorum: a mini-review.

Sclerotinia sclerotiorum is a typical necrotrophic plant pathogenic fungus, which has a wide host range and can cause a variety of diseases, leading to serious loss of agricultural production around the world. It is difficult to control and completely eliminate the characteristics, chemical control methods is not ideal. Therefore, it is very important to know the pathogenic mechanism of S. sclerotiorum for improving host living environment, relieving agricultural pressure and promoting economic development. In this paper, the life cycle of S. sclerotiorum is introduced to understand the whole process of S. sclerotiorum infection. Through the analysis of the pathogenic mechanism, this paper summarized the reported content, mainly focused on the oxalic acid, cell wall degrading enzyme and effector protein in the process of infection and its mechanism. Besides, recent studies reported virulence-related genes in S. sclerotiorum have been summarized in the paper. According to analysis, those genes were related to the growth and development of the hypha and appressorium, the signaling and regulatory factors of S. sclerotiorum and so on, to further influence the ability to infect the host critically. The application of host-induced gene silencing (HIGS)is considered as a potential effective tool to control various fungi in crops, which provides an important reference for the study of pathogenesis and green control of S. sclerotiorum.

Evaluation of heavy metal accumulation and tolerance in oxalic acid-treated Phragmites australis wetlands for textile effluent remediation.

Water contamination with metals poses significant environmental challenges. The occurrence of heavy metals (HMs) prompts modifications in plant structures, emphasizing the necessity of employing focused safeguarding measures. Cadmium (Cd), lead (Pb), and chromium (Cr) emerge as particularly menacing toxins due to their high accumulation potential. Increasing the availability of organic acids is crucial for optimizing toxic metal removal via phytoremediation. This constructed wetland system (CWs) was used to determine how oxalic acid (OA) treatments of textile wastewater (WW) effluents affected morpho-physiological characteristics, antioxidant enzyme activity, oxidative stress, and HM concentrations in Phragmites australis. Multiple treatments, comprising the application of OA at a concentration of 10 mM and WW at different dilutions (25%, 50%, 75%, and 100%), were employed, with three replications of each treatment. WW stress decreased chlorophyll and carotenoid content, and concurrently enhanced HMs adsorption and antioxidant enzyme activities. Furthermore, the application of WW was found to elevate oxidative stress levels, whereas the presence of OA concurrently mitigated this oxidative stress. Similarly, WW negatively affected soil-plant analysis development (SPAD) and the total soluble proteins (SP) in both roots and shoots. Conversely, these parameters showed improvement with OA treatments. P. australis showed the potential to enhance HM accumulation under 100% WW stress. Specifically, there is an increase in root SP ranging from 9% to 39%, an increase in shoot SP from 6% to 91%, and an elevation in SPAD values from 4% to 64% compared to their respective treatments lacking OA inclusion. The OA addition resulted in decreased EL contents in the root and shoot by 10%-19% and 13%-15%, MDA by 9%-14% and 9%-20%, and H2O2 by 14%-21% and 9%-17%, in comparison to the respective treatments without OA. Interestingly, the findings further revealed that the augmentation of OA also contributed to an increased accumulation of Cr, Cd, and Pb. Specifically, at 100% WW with OA (10 mM), the concentrations of Cr, Pb, and Cd in leaves rose by 164%, 447%, and 350%, in stems by 213%, 247%, and 219%, and in roots by 155%, 238%, and 195%, respectively. The chelating agent oxalic acid effectively alleviated plant toxicity induced by toxins. Overall, our findings demonstrate the remarkable tolerance of P. australis to elevated concentrations of WW stress, positioning it as an eco-friendly candidate for industrial effluent remediation. This plant exhibits efficacy in restoring contaminants present in textile effluents, and notably, oxalic acid emerges as a promising agent for the phytoextraction of HMs.

HMs stress decreased the physiology and morphology of Phragmites australis L.OA improved the photosynthetic pigments and antioxidant enzymesHMs accumulation and bioavailability increased under OAPhragmites australis L. showed higher efficacy for textile effluent treatment under OA.

Leaching of liquation-feeding furnace dross as a first step for germanium recovery.

OBJECTIVE: Germanium, an important component of electronics, is considered by many global economies as a critical raw material. Therefore, investigating its potential new sources is crucial for prospective technology development. This paper presents the investigation results on the leaching of liquation-feeding furnace dross using sulfuric and oxalic acid solutions. RESULTS: The dross contained mostly zinc (68.0% wt.) but also elevated germanium concentration (0.68% wt.). The influence of temperature, time, initial acid concentration, and liquid-to-solid phase ratio (L:S) was examined. It was found that germanium availability via leaching is limited-maximum leaching yields using aqueous solutions of sulfuric and oxalic acids were 60% (80 °C, 2 h, 15% wt. H2SO4, L:S 25:1) and 57% (80 °C, 3 h, 12.5% wt. H2C2O4, L:S 10:1), respectively.

Oxalic Acid Treatment: Short-Term Effects on Enzyme Activities, Vitellogenin Content, and Residual Oxalic Acid Content in House Bees, Apis mellifera L.

Honeybees (Apis mellifera L.) have to face many challenges, including Varroa destructor infestation, associated with viral transmission. Oxalic acid is one of the most common treatments against Varroa. Little is known about the physiological effects of oxalic acid, especially those on honeybees' immune systems. In this study, the short-term effects (0-96 h) of oxalic acid treatment on the immune system components (i.e., glucose oxidase, phenoloxidase, glutathione S-transferase, catalase activities, and vitellogenin contents) of house bees were preliminarily investigated. Oxalic acid contents of bee bodies and haemolymphs were also measured. The results confirm that oxalic acid is constitutively present in bee haemolymphs and its concentration is not affected by treatment. At 6 h after the treatment, a maximum peak of oxalic acid content was detected on bees' bodies, which gradually decreased after that until physiological levels were reached at 48 h. In the immune system, the oxalic acid treatment determined a peak in glucose oxidase activity at 48 h, indicating a potential defence response and an increase in vitellogenin content at 24 h. No significant changes were recorded in phenoloxidase, glutathione S-transferase, and catalase activities. These results suggest a time-dependent response to oxalic acid, with potential immune system activation in treated bees.

Preharvest Elicitors as a Tool to Enhance Bioactive Compounds and Quality of Both Peel and Pulp of Yellow Pitahaya (Selenicereus megalanthus Haw.) at Harvest and during Postharvest Storage.

Yellow pitahaya is a tropical fruit that has gained popularity in recent years. Natural elicitors are compounds that can stimulate the resistance and quality of fruits. The objective of this study was to evaluate the effects of natural elicitors, methyl salicylate (MeSa), methyl jasmonate (JaMe), salicylic acid (SA) and oxalic acid (OA) at concentrations of 0.1 mM (MeSa and JaMe) and 5 mM (SA and OA), applied to the yellow pitahaya fruits under greenhouse conditions. After full blossom, four applications were made with a frequency of 15 days. At the time of harvest and after storage, the following variables were evaluated: firmness (whole fruit), total soluble solids (TSS), total acidity (TA), phenolics and carotenoids (in the pulp), while phenolics, carotenoids, macronutrients and micronutrients were determined in the peel. The results showed MeSa advanced the fruit maturation, according to higher TSS, lower TA and firmness than MeJa-treated fruits, for which a delayed ripening process was shown. All treatments induced a higher polyphenolic concentration during storage. Regarding the alternative use of the peel as a by-product, the application of natural elicitors significantly increased the content of polyphenols, carotenoids, macronutrients and micronutrients in the peel, especially MeSa, which can be used as a bioactive compound in the food industry. In conclusion, the results indicate that natural elicitors can be an alternative to improve the quality and shelf life of yellow pitahaya fruits.

Treatment of marble industry wastewater by Brassica napus (L.) under oxalic acid amendment: efficacy as fodder and carcinogenic risk assessment.

In the present study, Brassica napus, a food plant, was grown for phytoextraction of selected heavy metals (HMs) from marble industry wastewater (WW) under oxalic acid (OA) amendment. The hydroponic experiment was performed under different combination of WW with OA in complete randomized design. Photosynthetic pigments and growth reduction were observed in plants treated with WW alone amendments. The combination of OA in combination with WW significantly enhanced the growth of plants along with antioxidant enzyme activities compared with WW-treated-only plants. HM stress alone enhanced the hydrogen peroxide, electrolyte leakage, and malondialdehyde contents in plants. OA-treated plants were observed with enhanced accumulation of cadmium (Cd), copper (Cu), and lead (Pb) concentrations in the roots and shoots of B. napus. The maximum concentration and accumulation of Cd in root, stem, and leaves was increased by 25%, 30%, and 30%; Cu by 42%, 24%, and 17%; and Pb by 45%, 24%, and 43%, respectively, under OA amendment. Average daily intake and hazard quotient (HQ) were calculated for males, females, and children in two phases of treatments in phytoremediation of metals before and after accumulation into B. napus leaves and stems. HQ of metals in the leaves and stem was < 1 before metal accumulation, whereas > 1 was observed after HM accumulation for all males, females, and children. Similarly, the hazard index of the three study types was found > 1. It was observed that the estimated excess lifetime cancer risk was of grade VII (very high risk), not within the accepted range of 1 × 10-4 to 1 × 10-6. Based on the present study, the increased levels of HMs up to carcinogenicity was observed in the B. napus which is not safe to be consumed later as food.

Application of phosphogypsum and phosphate-solubilizing fungi to Pb remediation: From simulation to in vivo incubation.

Phosphogypsum (PG) is the produced solid waste during phosphorus (P) extraction from phosphate rocks. PG is featured by its abundant PO43- and SO42-. This study investigated the utilization of PG as a material for lead (Pb) remediation, with the assistance of functional fungus. Aspergillus niger (A. niger) is a typical phosphate-solubilizing fungi (PSF), which has high ability to secret organic acids. Oxalic acid is its major secreted organic acid, which is often applied to enhance the P release from phosphate minerals. In this study, synthetic oxalic acid increased the immobilization rate of Pb2+ up to >99 % with the addition of PG. Then, it was observed that biogenic oxalic acid from A. niger can achieve comparable remediation effects. This was due to that PG could provide sufficient P for fungal growth, which allowed sustainable remediation. Subsequently, oxalic acid secreted by A. niger significantly increased the release of active P from PG, and then induced the formation of PPb minerals. In addition, other metabolites of A. niger (such as tyrosine-like substance) can also be complexed with Pb2+. Simultaneously, A. niger did not induce evidently elevation water-soluble fluorine (F) as PG contained abundant Ca2+. Moreover, this study elucidated that oversupply of PG promoted the formation of anglesite (Ksp = 1.6 × 10-8, relatively unstable), whereas the formation of lead oxalate (Ksp = 4.8 × 10-10, relatively stable) was reduced. This study hence shed a bright light on the sustainable utilization of PG for fungus-assisted remediation of heavy metals.

Ascorbic acid metabolism and functions.

This Special Issue was assembled to mark the 25th anniversary of the proposal of the d -mannose/ l -galactose (Smirnoff-Wheeler) ascorbate biosynthesis pathway in plants ( Wheeler et al., 1998 ). The issue aims to assess the current state of knowledge and to identify outstanding questions about ascorbate metabolism and functions in plants.

Effects of summer treatments against Varroa destructor on viral load and colony performance of Apis mellifera colonies in Eastern Canada.

Despite the use of various integrated pest management strategies to control the honey bee mite, Varroa destructor, varroosis remains the most important threat to honey bee colony health in many countries. In Canada, ineffective varroa control is linked to high winter colony losses and new treatment options, such as a summer treatment, are greatly needed. In this study, a total of 135 colonies located in 6 apiaries were submitted to one of these 3 varroa treatment strategies: (i) an Apivar® fall treatment followed by an oxalic acid (OA) treatment by dripping method; (ii) same as in (i) with a summer treatment consisting of formic acid (Formic Pro™); and (iii) same as in (i) with a summer treatment consisting of slow-release OA/glycerin pads (total of 27 g of OA/colony). Treatment efficacy and their effects on colony performance, mortality, varroa population, and the abundance of 6 viruses (acute bee paralysis virus [ABPV], black queen cell virus [BQCV], deformed wing virus variant A [DWV-A], deformed wing virus variant B [DWV-B], Israeli acute paralysis virus [IAPV], and Kashmir bee virus [KBV]) were assessed. We show that a strategy with a Formic Pro summer treatment tended to reduce the varroa infestation rate to below the economic fall threshold of 15 daily varroa drop, which reduced colony mortality significantly but did not reduce the prevalence or viral load of the 6 tested viruses at the colony level. A strategy with glycerin/OA pads reduced hive weight gain and the varroa infestation rate, but not below the fall threshold. A high prevalence of DWV-B was measured in all groups, which could be related to colony mortality.

Evaluating the seasonal efficacy of commonly used chemical treatments on Varroa destructor (Mesostigmata: Varroidae) population resurgence in honey bee colonies.

The purpose of this research was to determine how common chemical treatments influence Varroa destructor (Anderson and Trueman) population resurgence rates (defined as time posttreatment for mite populations to reach 3 mites/100 adult bees) in managed honey bee (Apis mellifera L.) colonies seasonally. We conducted 2 experiments that followed the same basic protocol to address this purpose. We established 6 treatment groups in Experiment 1 in the fall of 2014: untreated control, Apivar, Apistan, CheckMite+, ApiLifeVar, and Mite Away II applied to 10 colonies per treatment. In Experiment 2, we applied 8 chemical treatments to each of 4 seasonal (spring, summer, fall, and winter) cohorts of honey bee colonies to determine how mite populations are influenced by the treatments. The treatments/formulations tested were Apivar, Apistan, Apiguard, MAQS, CheckMite+, oxalic acid (dribble), oxalic acid (shop towels), and amitraz (shop towels soaked in Bovitraz). In Experiment 1, Apivar and Mite Away II were able to delay V. destructor resurgence for 2 and 6 months, respectively. In Experiment 2, Apiguard, MAQS, oxalic acid (dribble), and Bovitraz treatments were effective at delaying V. destructor resurgence for at least 2 months during winter and spring. Only the Bovitraz and MAQS treatments were effective at controlling V. destructor in the summer and fall. Of the 2 amitraz-based treatments, the off-label Bovitraz treatment was the only treatment to reduce V. destructor populations in every season. The data gathered through this study allow for the refinement of treatment recommendations for V. destructor, especially regarding the seasonal efficacy of each miticide and the temporal efficacy posttreatment.

Nitrogen migration and transformation characteristics of the soil in karst areas under the combined application of oxalic acid and urea inhibitors.

Objective: We investigated the horizontal migration and transformation of nitrogen in soil with oxalic acid and inhibitors (e.g., nitrification inhibitors, DMPP, urease inhibitors, and NBPT) under different soil water contents to provide a basis for the efficient utilization of nitrogen fertilizer in agricultural production in karst areas. Methods: Four nitrogen fertilizers (e.g., ammonium bicarbonate, ammonium sulfate, ammonium chloride, and urea) were applied separately and combined with oxalic acid, DMPP, and NBPT. The ammonium and nitrate nitrogen contents in the different soil layers were measured. The soil columns were cultured through an indoor soil column simulation at water content levels of 30%, 40%, and flooded (50%) for 30 days. Results: Ammonium bicarbonate with inhibitors increased soil NH4 +-N content by 15.42-21.12%. Ammonium sulfate with oxalic acid or NBPT increased soil NH4 +-N content by 27.56-52.25% at 30% and 40% moisture content treatments, compared to ammonium sulfate alone. Urea with DMPP application significantly increased soil NH4 +-N content by 11.93-14.87% at 40% water content and flooded conditions. In all treatments, the NH4 +-N content in the soil treated with 30% water content of ammonium chloride with oxalic acid was the highest. The NH4 +-N content showed a decreasing trend with an increase in the water content. The NO3 --N content in soil treated with ammonium bicarbonate and DMPP was higher than that treated with other nitrogen fertilizers at 30% moisture. The NO3 --N content decreased with increased water content. Under all treatments, ammonium chloride with oxalic acid had the highest percentage of soil NH4 +-N and soil soluble inorganic nitrogen at 30% water content, with 55.29% and 55.97%, respectively. Conclusion: Among the nitrogen fertilizer treatments, the soil NH4 +-N content increased in ammonium bicarbonate with DMPP or NBPT, ammonium sulfate with oxalic acid or NBPT, and urea with DMPP. The four nitrogen fertilizers with DMPP increased the soil NO3 --N content. Nitrogen fertilizer combined with oxalic acid and inhibitors could effectively improve the effective use of nitrogen fertilizer.

Role of oxalic acid in fungal and bacterial metabolism and its biotechnological potential.

Oxalic acid and oxalates are secondary metabolites secreted to the surrounding environment by fungi, bacteria, and plants. Oxalates are linked to a variety of processes in soil, e.g. nutrient availability, weathering of minerals, or precipitation of metal oxalates. Oxalates are also mentioned among low-molecular weight compounds involved indirectly in the degradation of the lignocellulose complex by fungi, which are considered to be the most effective degraders of wood. The active regulation of the oxalic acid concentration is linked with enzymatic activities; hence, the biochemistry of microbial biosynthesis and degradation of oxalic acid has also been presented. The potential of microorganisms for oxalotrophy and the ability of microbial enzymes to degrade oxalates are important factors that can be used in the prevention of kidney stone, as a diagnostic tool for determination of oxalic acid content, as an antifungal factor against plant pathogenic fungi, or even in efforts to improve the quality of edible plants. The potential role of fungi and their interaction with bacteria in the oxalate-carbonate pathway are regarded as an effective way for the transfer of atmospheric carbon dioxide into calcium carbonate as a carbon reservoir.

Synergetic conditioning via oxalic acid enhanced Fe2+/CaO2 and skeleton construct to achieve deep dewatering of sewage sludge.

Extracellular polymeric substance (EPS) with highly hydrophilic groups and sludge with high compressibility are determined sludge dewaterability. Herein, Fe2+ catalyzed calcium peroxide (CaO2) assisted by oxalic acid (OA) Fenton-like process combined with coal slime was applied to improve sludge dewaterability. Results demonstrated that the sludge treated by 0.45/1/1.1-OA/Fe2+/CaO2 mM/g DS, the water content (WC), specific resistance to filtration and capillary suction time dropped to 53.01%, 24.3 s and 1.2 × 1012 m/kg, respectively. Under coal slime ratio as 0.6, WC and compressibility were further reduced to 42.72% and 0.66, respectively. The hydroxyl radicals generated by OA/Fe2+/CaO2 under near-neutral pH layer by layer collapsed EPS, resulting in the degradation and migration of inner releasing components and the exposure of inner sludge flocs skeleton. The hydrophilic tryptophan-like protein of TB-EPS were degraded into aromatic protein of S-EPS and exposed inner hydrophobic sites. The protein secondary structures were transformed by destroying hydrophilic functional groups, which were attributed to the reducing α-helix ratio and reconstructing ß-sheet. Moreover, coal slime as the skeleton builder lowered compressibility and formed more macropores to increase the filterability of pre-oxidized sludge for the higher intensity of rigid substances. This study deepened the understanding of OA enhanced Fenton-like system effects on sludge dewaterability and proposed a cost-effective and synergistic waste treatment strategy in sludge dewatering.

The dissipation of organophosphate esters mediated by ryegrass root exudate oxalic acid in soil: Analysis of enzymes activities, microorganism.

Complex rhizoremediation is the main mechanism of phytoremediation in organic-contaminated soil. Low molecular weight organic acids (LMWOAs) in root exudates have been shown to increase the bioavailability of contaminants and are essential for promoting the dissipation of contaminants. The effects of root exudates on the dissipation of organophosphate esters (OPEs) in soil are unclear. Consequently, we studied the combined effects of root exudates, soil enzymes and microorganisms on OPEs (tri (1-chloro-2-propyl) phosphate (TCPP) and triphenyl phosphate (TPP)) dissipation through pot experiments. Oxalic acid (OA) was confirmed to be the main component of LMWOAs in root exudates of ryegrass. The existence of OA increased the dissipation rate of OPEs by 6.04%-25.50%. Catalase and dehydrogenase activities were firstly activated and then inhibited in soil. While, urease activity was activated and alkaline phosphatase activity was inhibited during the exposure period. More bacteria enrichment (e.g., Sphingomonas, Pseudomonas, Flavisolibacter, Pontibacter, Methylophilus and Massilia) improved the biodegradation of OPEs. In addition, the transformation paths of OPEs hydrolysis and methylation under the action of root exudates were observed. This study provided theoretical insights into reducing the pollution risk of OPEs in the soil.

A comprehensive review of recent advances in the applications and biosynthesis of oxalic acid from bio-derived substrates.

Organic acids are important compounds with numerous applications in different industries. This work presents a comprehensive review of the biological synthesis of oxalic acid, an important organic acid with many industrial applications. Due to its important applications in pharmaceuticals, textiles, metal recovery, and chemical and metallurgical industries, the global demand for oxalic acid has increased. As a result, there is an increasing need to develop more environmentally friendly and economically attractive alternatives to chemical synthesis methods, which has led to an increased focus on microbial fermentation processes. This review discusses the specific strategies for microbial production of oxalic acid, focusing on the benefits of using bio-derived substrates to improve the economics of the process and promote a circular economy in comparison with chemical synthesis. This review provides a comprehensive analysis of the various fermentation methods, fermenting microorganisms, and the biochemistry of oxalic acid production. It also highlights key sustainability challenges and considerations related to oxalic acid biosynthesis, providing important direction for further research. By providing and critically analyzing the most recent information in the literature, this review serves as a comprehensive resource for understanding the biosynthesis of oxalic acid, addressing critical research gaps, and future advances in the field.

Facet-dependent activation of oxalic acid over hematite nanocrystals under the irradiation of visible light for efficient degradation of pollutants.

Naturally occurring hematite has been widely studied in the Fenton-like system for water pollutant remediation due to its abundance and non-toxicity. However, its inadequate catalytic activity results in difficulty in effectively degrading pollutants in the catalytic degradation system that it constitutes. Thus, we constructed a photochemical system composed of hematite with {001} facet of high activity facet and low-cost and non-toxic oxalic acid (OA) for the removal of various types of pollutants. The removal rate for the degradation of metronidazole, tetracycline hydrochloride, Rhodamine B, and hexavalent chromium by hematite nanoplate with the exposed {001} facet activating OA under visible light irradiation was 4.75, 2.25, 2.33, and 2.74 times than that by the exposed {110} facet, respectively. Density functional theory (DFT) calculation proved that the OA molecule was more easily adsorbed on the {001} facet of hematite than that on the {110} facet, which would favor the formation of the more Fe(III)-OA complex and reactive species. In addition, the reactive site of metronidazole for the attraction of radicals was identified on the basis of the DFT calculation on the molecular occupied orbitals, and the possible degradation pathway for metronidazole included carbon chain fracture, hydroxyethyl-cleavage, denitrogenation, and hydroxylation. Thus, this finding may offer a valuable direction in designing an efficient iron-based catalyst based on facet engineering for the improved activity of Fenton-like systems such as OA activation.

Oxalic acid secretion alleviates saline-alkali stress in alfalfa by improving photosynthetic characteristics and antioxidant activity.

Saline-alkali stress significantly affects the growth and yield of alfalfa (Medicago sativa L.). Organic acid secretion is crucial in alleviating abiotic stress-induced damage in plants. In this study, we evaluated the contents of the major organic acids secreted by the roots of tolerant (ZD) and sensitive (LYL) varieties of alfalfa under saline-alkali stress and investigated the effects of these organic acids on the growth, and physiological functions of alfalfa. Our results indicated that the oxalic acid (OA) content was the highest among the organic acids secreted from alfalfa roots under saline-alkali stress, and oxalic acid content was the most significantly different between the two varieties, ZD and LYL, compared to the contents of the other organic acids. Oxalic acid alleviated the inhibition of alfalfa growth caused by saline-alkali stress, improved photosynthetic characteristics, reduced the accumulation of reactive oxygen species, and increased the activity of antioxidant enzymes and content of osmoregulatory substances. Furthermore, oxalic acid resulted in significantly increased expression of genes involved in photosynthesis and antioxidant system in alfalfa under saline-alkali stress. This study revealed the effects of oxalic acid secreted by the root system on stress-related physiological processes, providing valuable insights into the functions of root secretions in plant saline-alkali resistance.

An environmentally friendly strategy for reducing the environmental risks of heavy metals adsorbed by kaolinite.

Plenty of heavy metals (HMs) that are adsorbed on clay minerals (such as kaolinite), in addition to low molecular-weight organic acids (such as oxalic acid (OA)) with high activities, are widespread in the natural environment. In the present study, the effects of OA on the environmental behaviors of Pb2+/Cd2+ adsorbed by kaolinite have been investigated. The effectiveness and mechanisms of calcium silicate (CS) and magnesium silicate (MS) in reducing the environmental risks of the HMs have also been studied. The results showed that the releases of Pb2+/Cd2+ increased with an increasing concentration of OA. When different dosages of CS/MS were added to the aging system, a redistribution of HMs took place and the free form of Pb2+/Cd2+ decreased to very low levels. Also, the unextractable Pb2+/Cd2+ increased to high levels. Furthermore, a series of characterizations showed that the released HMs were re-captured by the CS/MS. In addition, the CS immobilized the OA in the solution during the aging process, which also facilitated an immobilization of the carbon element in the environment. In general, the present study has contributed to a further understanding of the transport behaviors of the HMs in natural environments, and of the interactions between CS (or MS), the environmental media, and the heavy metal contaminants. In addition, this study has also provided an eco-friendly strategy for an effective remediation of heavy metal pollution.

Fully Bio-Based 2,5-Furandicarboxylic Acid Polyester toward Plastics with Mechanically Robust, Excellent Gas Barrier and Fast Degradation.

Aliphatic-aromatic copolyesters offer a promising solution to mitigate plastic pollution, but high content of aliphatic units (>40 %) often suffer from diminished comprehensive performances. Poly(butylene oxalate-co-furandicarboxylate) (PBOF) copolyesters were synthesized by precisely controlling the oxalic acid content from 10 % to 60 %. Compared with commercial PBAT, the barrier properties of PBOF for H2O and O2 increased by more than 6 and 26 times, respectively. The introduction of the oxalic acid units allowed the water contact angle to be reduced from 82.5° to 62.9°. Superior hydrophilicity gave PBOF an excellent degradation performance within a 35-day hydrolysis. Interestingly, PBO20F and PBO30F also displayed obvious decrease of molecular weight during hydrolysis, with elastic modulus >1 GPa and tensile strength between 35-54 MPa. PBOF achieved the highest hydrolysis rates among the reported PBF-based copolyesters. The hydrolytic mechanism was further explored based on Fukui function analysis and density functional theory (DFT) calculation. Noncovalent analysis indicated that the water molecules formed hydrogen bonding interaction with adjacent ester groups and thus improved the reactivity of carbonyl carbon. PBOF not only meet the requirements of the high-performance packaging market but can quickly degrade after the end of their usage cycles, providing a new choice for green and environmental protection.

"Synthesis and characterization of mesoporous V-Mo-MCM-41 nanocatalysts: Enhancing efficiency in oxalic acid synthesis".

Mesoporous V-Mo-MCM-41 nano molecular sieves were synthesized via the direct hydrothermal method, employing tetraethyl orthosilicate (TEOS) as a silica source and cetyltrimethylammonium bromide (CTAB) as a surfactant template. Comprehensive characterization through N2-adsorption (BET), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) confirmed the mesoporous nature of the catalysts, revealing variations in specific surface area and a significant pore diameter of 6.3 nm, enhancing their versatility for various chemical transformations. The nanoscale structure was further validated through XRD analysis and SEM images. The catalytic efficiency of V-Mo-MCM-41 was demonstrated by synthesizing oxalic acid from molasses, and a response surface methodology (RSM) study on four key variables revealed a maximum yield of 83 % within 1 h using minimal sulfuric acid, showcasing the effectiveness of the prepared catalysts.