Changes In Functional Groups Research Articles

Study on Microstructure Evolution Characteristics of Coal in Low Temperature Oxidation Stage in Goaf of Longfeng Coal Mine

ABSTRACT Low temperature oxidation of coal is the nature of oxidation of coal with oxygen molecules at temperatures below its oxidation critical point or ignition point, usually from ambient temperature to about 200°C. Air leakage and uneven oxygen distribution significantly impact coal spontaneous combustion in goaf. Understanding the changes in free radicals and functional groups during low-temperature oxidation of coal under different oxygen concentrations is crucial for preventing and controlling residual coal self-ignition. This study employs Fourier transform infrared spectroscopy to analyze the effects of varying oxygen concentrations (3%, 5%, 9%, 15%, 21%) on functional groups and structural parameters during coal’s low-temperature oxidation. Results indicate that increasing oxygen concentration promotes the consumption of oxygen-containing functional groups, reducing their content from 71.9% to 52%. Concurrently, the activity and content of aromatic hydrocarbon functional groups rise rapidly from 4.8% to 52.6%. The aliphatic hydrocarbon structure shows a downward trend, indicating its minimal presence. Aromatic ring condensation increases coal sample aromaticity, suggesting higher maturity and weaker hydrocarbon generation potential, with minimal effect from oxygen concentration. Early-stage reactions show little change in coal’s basic structure, and coal-oxygen reactions remain low in low oxygen environments. This study provides an important basis for understanding the mechanism of coal spontaneous combustion in goaf and formulating effective prevention measures for coal spontaneous combustion.

Study on pyrolysis process and mechanism of organic coating of waste polyesterimide enameled wire based on density functional theory

The pyrolysis treatment of waste polyesterimide enameled wire offers significant advantages such as continuous processing, non-hazardous nature, and high resource recovery rate. However, research on its pyrolysis process and mechanism remains insufficiently explored. In this study, techniques including thermogravimetry (TG), Fourier transform infrared spectroscopy(FT-IR), pyrolysis–gas chromatography-mass spectrometry(Py-GC/MS) were employed to investigate pyrolysis temperature, weight loss rate, pyrolysis and kinetic parameters, composition and distribution of pyrolysis products, and changes in functional groups under different temperatures and heating rates. The pyrolysis of polyesterimide enameled wire can be divided into three stages: volatilization of specific components (314.8 °C,1.6 %), rapid decomposition of polyesterimide (435.2 °C, 44.7 %), and generation of small organic molecules with the fixation of pyrolytic carbon (750 °C, 9.0 %). The main components of the pyrolysis gas products include aromatic compounds, ethers, aromatics, ketones, and carbon dioxide. At 400 °C, a substantial amount of pyrolysis gas products and free radicals are produced, with an increase in aromatic hydrocarbons. The carbon distribution in the pyrolysis products mainly focuses on C6-C10 and C11-C15, and many organic compounds such as benzoic acid, phenol, and aniline are generated. Based on density functional theory, the bond dissociation energies in the polyesterimide were calculated. This clarified the possible thermal decomposition pathways of the polyesterimide and provided the energy barrier values, elucidating the generation mechanism of pyrolysis products during thermal decomposition. The copper atom in specific location reduces the negative ESP of O and increases the positive ESP of H in EPI, which makes H more likely to attach to O. The presence of Cu increases the ESP range and promote the pyrolysis process. This study provides a theoretical basis for the high-value recycling of waste polyesterimide enamelled wire.

Preliminary investigation of the effects of high-temperature thermal activation on the activity of graphite tailings and the mechanical properties of graphite tailings mortar

The disposal of graphite tailings, a byproduct of graphite mining, poses significant recycling challenges. This study explores eco-friendly cement mortar by partially replacing sand with activated graphite tailings, focusing on waste utilization. Activating the pozzolanic properties of graphite tailings at various thermal activation temperatures converts them into high-quality binder materials. Quantitative assessments of graphite tailings' activity, conducted through ion leaching tests and raw material diffraction analysis, produce an activity index Ka, evaluating their performance under different thermal activation temperatures. Variable testing of substitution rates and activation temperatures examines changes in mechanical properties, microstructure, and pore distribution of the graphite tailings mortar. Optimum results reveal a 30 % substitution rate and a 750°C activation temperature. Graphite tailings, as pozzolanic binder materials, enhance mortar strength by improving particle size distribution, reducing "micro-area bleeding" and "boundary effects". After thermal activation, reactive minerals on the tailings' surface undergo secondary hydration reactions with cementitious products, modifying chemical structures and micro-morphology at the interface. Semi-quantitative XRD analysis and FT-IR spectroscopy characterize the ensuing chemical reactions, unveiling molecular bond and functional group changes. The superior performance of thermally activated graphite tailings primarily stems from increased active SiO2 and Al2O3 post-activation. The active SiO2 and Al2O3 reacts with cementitious products to form C-(A)-S-H gels, filling micro-pores at the tailings-mortar interface, which is the key characteristic that enables graphite tailings to serve as high-quality pozzolanic binder aggregates. A predictive model for compressive strength, utilizing reference models from solid waste mortar concrete, quantifies the positive impact of chemical activation. The theoretical results obtained from this predictive model closely align with the experimental findings.

Mitigating Health Risks Through Biosorption: Effective Removal of Nickel (II) and Chromium (VI) from Water with Acid-Treated Potato Peels

Introduction: Nickel (Ni(II)) and chromium (Cr(VI)) are associated with serious health risks, including respiratory problems, kidney damage, and cancer, along with potential threats to ecosystems. Given their persistence and significant toxicity, effective removal from contaminated water is essential to mitigate these health risks. This study explores the efficacy of acid-treated potato peels (ATPP) as an economical and readily accessible biosorbent for the removal of Ni(II) and Cr(VI) from water solutions. Methods: The study explored two biosorbents: raw potato peels (RPP) and ATPP. Fourier Transform Infrared (FTIR) spectroscopy was utilized to analyze changes in surface functional groups. Batch biosorption experiments were performed using distinct contact times (30-180min), pH (3–11), and biosorbent dosages (0.1–0.5 g). The Mann-Whitney U test was applied for the statistical analysis. Results and Discussion: The FTIR analysis indicated an enhancement in carboxyl groups on the ATPP surface after acid treatment, with stronger transmittance peak at 1645 cm⁻¹. ATPP showed significant improvements in biosorption capacity compared to RPP, removing 18.23% of 10 mg/L Ni(II) at pH 5 in 120minutes using 0.5 g of ATPP. For Cr(VI), 52.28% removal was achieved at pH 7 with 0.2 g of ATPP within the same time frame. Statistical analysis confirmed the superior performance of ATPP in removing Ni(II) (p = 0.024) and Cr(VI) (p = 0.004). Conclusion: ATPP offers significantly higher biosorption capabilities than RPP attributed to the increased presence of carboxyl groups on the modified surface, indicating potential for eco-friendly effective material in mitigating the heavy metal pollution's health risks.

Effect of ultrasound power on moisture status change of apple by contact ultrasound reinforced far-infrared radiation drying

To explore the effect of ultrasound power on internal water change of apple dried by contact ultrasound enhanced far-infrared radiation drying (CUFRD), the drying characteristics, microstructure, moisture migration, and molecular vibration patterns of apple slices subjected to this process at different ultrasound powers were investigated using low-field nuclear magnetic resonance (LF-NMR), Near-infrared (NIR) and two-dimensional(2D) correlation analysis. With the increase of contact ultrasound (CU) power, the drying times of apple were shortened by 8.69% to 17.39%, respectively. Scanning electron microscopy (SEM) observation indicated that higher CU power resulted in an increase in the number of microporous channels and pore diameter within apple’s internal tissue. The findings of LF-NMR clarified that free water content kept decreasing, while the content of semi-bound water initially increased and then reduced. Magnetic resonance imaging (MRI) images illustrated that higher CU power corresponded to a faster decrease in the redness value of the H+ density map of apple during drying. 2D correlation analysis revealed that the changes in the O-H bonds of apple were prioritized over the C-H bonds during drying process. NIR spectroscopy and LF-NMR heterogeneous correlation spectrograms demonstrated that at wavelengths of 950, 1450, and 1680 nm, the order of changes in water-related functional groups was quadruple-frequency O-H > combination of the first overtone of O-H stretching and OH-bending band > double-frequency C-H. Moreover, with increasing CU power, the vibration of hydrogen-containing functional groups intensified, leading to increased water activity. Thus, CU application could significantly enhance the CUFRD process of apple slices.

Effect of Drying Methods and Harvest Age on the Quality of Sliced Tiwai Onion (Eleutherine americana Merr) as A Potential Functional Food

Tiwai onion (Eleutherine americana L. Merr) is renowned for therapeutic properties due to the bioactive constituents, including polyphenol, flavonoid, and tannin. Therefore, this study aimed to characterize water content, ash, fat, protein, polyphenol, flavonoid, tannin, and antioxidant capacity, as well as to observe the functional groups and morphology of dried tiwai powder. The methodology comprised 2 factors, namely harvest age and drying methods. The results showed significant effects of harvest age and drying methods on water, fat, total phenol, total flavonoid, anthocyanin content, and antioxidant capacity, while ash, protein, and tannin content were not significantly affected. In Fourier Transform Infrared Spectroscopy (FTIR) analysis, changes in functional groups were observed, although not significant in wave numbers range of 1,800 - 1,350 and 1,200 - 950 cm−1. Specifically, an increase was observed in signals from C-C, C-O, and C-O-C vibrations. Scanning Electron Microscopy (SEM) at 1000x magnification showed that air drying at 5 months of harvest age produced dense granules, while electric oven and microwave drying of older harvests led to a flatter structure and crumbly texture. HIGHLIGHTS Tiwai Onion's Medicinal Properties: Tiwai onion (Eleutherine americana Merr) is traditionally used in Indonesia for its medicinal properties, including high levels of polyphenols, flavonoids, and tannins, which contribute to its antioxidant potential, protecting cells from free radicals and supporting overall health. Impact of Drying Methods: The study compares three drying methods-air, electric oven, and microwave-on the water content and bioactive compounds in tiwai. Microwave drying is shown to preserve bioactive compounds like phenols and flavonoids better, while air drying is more suited for heat-sensitive products. Chemical Content Variability: The drying method and harvest age significantly affect the chemical composition of tiwai, including water, fat, protein, and phenolic content. Microwave drying at 5 and 7 months resulted in the highest total phenol content, while air drying retained the most flavonoids at 9 months. Antioxidant Capacity: Despite the different drying methods, no significant variation was observed in the antioxidant capacity of tiwai at different harvest ages. However, microwave drying shows promising results in preserving the active compounds and antioxidant properties. Microstructural Effects: Scanning Electron Microscopy (SEM) revealed that air drying leads to denser, irregular granules with lower solubility, while microwave drying creates more brittle, compact structures, improving solubility and rehydration capacity. GRAPHICAL ABSTRACT

Competitive adsorption of oxytetracycline and sulfamethoxazole by nanosized activated carbon in aquatic environments: Experimental analysis and DFT calculations

Nanosized activated carbon (NAC) is an emerging carbonaceous nanomaterial for water treatment, while oxytetracycline (OTC) and sulfamethoxazole (SMX) coexisting in aquatic environments may undergo competitive adsorption to influence its removal efficiency. This study investigated the competitive adsorption of OTC and SMX onto NAC under different interaction sequence, pH, electrolyte, and water matrix conditions, using experimental analysis and density function theory (DFT) calculations. Adsorption kinetics show that increasing concentration of one antibiotic inhibited the adsorption of another. Faster equilibrium was attained in binary systems than single systems due to competitive adsorption, with pseudo-second-order model providing the best fit in both systems. Adsorption isotherms suggest that NAC exhibited stronger affinity towards OTC (395.26 mg/g) than SMX (232.02 mg/g), with Langmuir model showing satisfactory fitting in both single and binary systems. Sequential adsorption of [NAC + OTC] + SMX was more favored than binary adsorption, aligning with the optimum configuration of SMX--[NAC-OTC±] with binding energy of −57.25 kcal/mol from DFT calculations. Competitive adsorption was preferred within pH 3.2–5.6, where electrostatic attraction existed between NAC and cationic antibiotics. Salting-out, charge screening, and complexation effects from Na+ and Ca2+ influenced competitive adsorption. Optimal removal of OTC and SMX by NAC was achieved in wastewater effluent among four water matrices in both single and binary systems. Hydrogen bonding, π − π electron donor–acceptor interactions, electrostatic interactions, and hydrophobic interactions contributed to adsorption. Sequential change in functional groups of NAC followed − OH → C − H → C − O → C = C and C = C → C − O → C − H → − OH in single and binary systems, respectively. The findings provide valuable insights into the competitive adsorption mechanisms of antibiotics on NAC, highlighting its potential for remediating mixtures of antibiotics in complex aquatic environments.

The effect of ultraviolet radiation on asphalt functional group through FTIR and EW method

Ultraviolet (UV) ageing is an important factor affecting the service performance of asphalt pavement. However, at present, the group transformation of asphalt under ultraviolet radiation is still need to be studied. The ageing mechanism of asphalt could be better revealed through studying the functional groups of asphalt. In this study, asphalt were aged by three kinds of ultraviolet light. The changes of characteristic functional groups of asphalt before and after ultraviolet ageing were analyzed by infrared spectroscopy. Finally, the entropy weight method was used to calculate the count of inter conversion. The results showed that the carbonyl index of asphalt increased after ultraviolet ageing, while the methylene index, aromatic index, aliphatic index, and sulfoxide index decreased. After the asphalt is aged by ultraviolet, the C-C, C-H and C=C bonds in the asphalt material will be converted to C=O, and S=O will be converted to SO2. The results could be used to simulate asphalt molecules in order to better understand the performance and properties of asphalt.

Probiotic Lactobacillus plantarumLP28 and Saccharomyces cerevisiae improve the bioactive content and quality of fruit‐based rice beverage

AbstractThe increasing demand for plant‐based beverages with improved functional and sensory qualities has guided this study, which examines the bioactive content, functional, and sensory properties of a rice, apple pomace, and sea buckthorn beverage (RASB) fermented with probiotic Lactobacillus plantarum and Saccharomyces cerevisiae. We found out that total polyphenol content (TPC), total flavonoid content (TFC), and β‐carotene were significantly higher in samples with Saccharomyces cerevisiae, particularly in coculture samples. These samples also exhibited elevated alcohol by volume (ABV). Monoculture samples showed increased total flavonol content (TFLC), total anthocyanin content (TAC), and proanthocyanidin. The RASB‐LP sample, containing only Lactobacillus plantarum, revealed the highest antioxidant properties, evidenced by DPPH (94.13 ± 0.05%) and ABTS (97.69 ± 0.09%) assays. Interestingly, 3‐methylbutyl 3‐methylbutanoate, abundant in the unfermented control, was hydrolyzed to 3‐methyl‐1‐butanol in fermented samples, especially those containing Saccharomyces cerevisiae. Sensory evaluation evidenced that RASB‐LP scored highest for aroma and overall acceptability. FTIR analysis also indicated changes in functional groups of RASB samples. Together, our findings suggest that a novel probiotic cereal beverage with enhanced quality can be developed through the addition of fruit and fruit pomace, coupled with fermentation using Lactobacillus plantarum LP28 and Saccharomyces cerevisiae.

Aged Microplastics and Antibiotic Resistance Genes: A Review of Aging Effects on Their Interactions.

Background: Microplastic aging affects the dynamics of antibiotic resistance genes (ARGs) on microplastics, yet no review presents the effects of microplastic aging on the associated ARGs. Objectives: This review, therefore, aims to discuss the effects of different types of microplastic aging, as well as the other pollutants on or around microplastics and the chemicals leached from microplastics, on the associated ARGs. Results: It highlights that microplastic photoaging generally results in higher sorption of antibiotics and ARGs due to increased microplastic surface area and functional group changes. Photoaging produces reactive oxygen species, facilitating ARG transfer by increasing bacterial cell membrane permeability. Reactive oxygen species can interact with biofilms, suggesting combined effects of microplastic aging on ARGs. The effects of mechanical aging were deduced from studies showing larger microplastics anchoring more ARGs due to rough surfaces. Smaller microplastics from aging penetrate deeper and smaller places and transport ARGs to these places. High temperatures are likely to reduce biofilm mass and ARGs, but the variation of ARGs on microplastics subjected to thermal aging remains unknown due to limited studies. Biotic aging results in biofilm formation on microplastics, and biofilms, often with unique microbial structures, invariably enrich ARGs. Higher oxidative stress promotes ARG transfer in the biofilms due to higher cell membrane permeability. Other environmental pollutants, particularly heavy metals, antibacterial, chlorination by-products, and other functional genes, could increase microplastic-associated ARGs, as do microplastic additives like phthalates and bisphenols. Conclusions: This review provides insights into the environmental fate of co-existing microplastics and ARGs under the influences of aging. Further studies could examine the effects of mechanical and thermal MP aging on their interactions with ARGs.

“Efficient novel fungal-enriched biochar formulation for hexavalent chromium bioremediation”

Chromium (Cr), a key element in industrial processes such as leather tanning, poses severe environmental hazards, particularly its hexavalent form, Cr(VI), which is highly toxic and prevalent in tannery effluents/sludge. The persistence and toxicity of Cr(VI) necessitate the development of effective remediation strategies to mitigate its environmental impact. This study investigated the potential of Trichoderma yunnanense (NBRICRF_97) and its combination with 0.5% sugarcane bagasse biochar (SBC) for the reduction of Cr(VI). The results demonstrated that T. yunnanense alone achieved a 91.04% reduction of 50 mg L−1 Cr(VI) within 72 h. Combined with 0.5% SBC, the reduction efficiency increased to 99.65% within 48 h. However, the efficiency decreased at higher concentrations (200 mg L−1). The combination also improved fungal growth and increased extracellular ChrR enzyme activity (13.07 U mg−1 protein compared to the control). Total glutathione activity was boosted by 161.07% at 100 mg L−1 Cr(VI). Antioxidant enzymes (SOD, POD, CAT) and proline mitigated oxidative stress and FTIR analysis revealed changes in fungal cell wall functional groups (-OH and -NH) upon Cr(VI) exposure. SEM-EDX confirmed chromium deposition on fungal surfaces. These results underscore the Cr(VI) detoxification capabilities of T. yunnanense and the synergistic benefits of SBC, suggesting a promising bioremediation strategy for Cr(VI)-contaminated environments. The integration of T. yunnanense with SBC offers a sustainable and cost-effective approach for the bioremediation of Cr(VI)-contaminated sites, with potential for implementation in large-scale environmental cleanup efforts.

Degradation of diesel fuel by Pseudomonas aeruginosa B031 with expression of the alkB gene in a column bioreactor

Diesel fuel pollutants contain toxic hydrocarbons dominated by aliphatic and aromatic hydrocarbons. Hydrocarbon pollutants can be degraded in an environmentally friendly manner through bioremediation using hydrocarbonoclastic bacteria, i.e., Pseudomonas aeruginosa B031, which harbors the alkB gene that encodes an alkane hydroxylase that degrades alkane chains in hydrocarbons. This study compared the ability and efficiency of P. aeruginosa B031 to degrade diesel pollutants in a batch system and a continuous system using a column bioreactor, as well as the expression of alkB. P. aeruginosa B031 could more efficiently degrade diesel fuel in a continuous system in a column bioreactor than in the batch system. The concentrations of phenol, total organic carbon, chemical oxygen demand, and biological oxygen demand in the column bioreactor underwent a greater decrease than those in the batch system, namely 1.5-fold, 1.7-fold, 1.4-fold, and 1.3-fold, respectively. The decrease in these concentrations was followed by changes in functional groups, as shown via Fourier transform infrared spectroscopy. The number of bacteria and the concentration of exopolysaccharide increased in the column bioreactor by 4-fold and 2.3-fold more than the increase in the batch system. The ability of P. aeruginosa B031 to degrade diesel fuel in the column bioreactor was also demonstrated by the higher expression of alkB than that in the control.

Recovery of Soil Microbial Metabolism After Rewetting Depends on Interacting Environmental Conditions and Changes in Functional Groups and Life History Strategies.

Climate change is causing an intensification of soil drying and rewetting events, altering microbial functioning and potentially destabilizing soil organic carbon. After rewetting, changes in microbial community carbon use efficiency (CUE), investment in life history strategies, and fungal to bacterial dominance co-occur. Still, we have yet to generalize what drives these dynamic responses. Here, we collated 123 time series of microbial community growth (G, sum of fungal and bacterial growth, evaluated by leucine and acetate incorporation, respectively) and respiration (R) after rewetting and calculated CUE = G/(G + R). First, we characterized CUE recovery by two metrics: maximum CUE and time to maximum CUE. Second, we translated microbial growth and respiration data into microbial investments in life history strategies (high yield (Y), resource acquisition (A), and stress tolerance (S)). Third, we characterized the temporal change in fungal to bacterial dominance. Finally, the metrics describing the CUE recovery, investment in life history strategies, and fungal to bacterial dominance after rewetting were explained by environmental factors and microbial properties. CUE increased after rewetting as fungal dominance declined, but the maximum CUE was explained by the CUE under moist conditions, rather than specific environmental factors. In contrast, higher soil pH and carbon availability accelerated the decline of microbial investment in stress tolerance and fungal dominance. We conclude that microbial CUE recovery is mostly driven by the shifting microbial community composition and the metabolic capacity of the community, whereas changes in microbial investment in life history strategies and fungal versus bacterial dominance depend on soil pH and carbon availability.

Transport of microplastics treated with dielectric barrier discharge (DBD) plasma in saturated porous media

The performance of discharge plasma in treating organic pollutants and micro-organisms in water is impressive. When discharge plasma is used to treat polluted water containing organic pollutants and microorganisms, the presence of a certain amount of microplastics (MPs) in the water is unavoidable due to the complexity of the components contained in the water and the prevalence of MPs. MPs, as one of the pollutants that are difficult to be degraded by discharge plasma, undergo physical and chemical changes that increase their risk in the environment after treatment. Therefore, it is necessary to understand the fate of MPs after being treated with discharge plasma. In this study, the surface morphology of plastics before and after discharge plasma treatment was observed by scanning electron microscopy (SEM). The plastics after discharge plasma treatment were characterized by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) to determine the changes in oxygen-containing functional groups on the surface. The recovery of microplastics (MPs) in saturated porous media under different physicochemical and plasma oxidation conditions was investigated by column experiments. It has been shown that MPs exhibit increased recovery under conditions of increased flow rate and pH. A decrease in recovery was observed at elevated ionic strength and co-existing cation valence. High voltages and low air flow rates increase the oxidation of MPs by increasing the thermal effects of the dielectric barrier discharge (DBD) plasma system, the amount of reactive oxygen species (ROS) and the intensity of ultraviolet ray (UV) irradiation. The mobility of MPs is enhanced by a combination of these factors. The advection–dispersion equation (ADE) fits the transport data of MPs well. The interaction energy between quartz sand and MPs was calculated using the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. This study provides a new perspective on the potential risks of discharge plasma in water treatment.

In vitro dynamic digestion properties and fecal fermentation of Dictyophora indusiata polysaccharide: Structural characterization and gut microbiota

The in vitro dynamic digestive model more realistically simulates the human digestive system compared to static digestive model. In this study, the dynamic in vitro stomach-intestine digestive system and fecal fermentation was used to investigate the dynamic digestion properties and fermentation properties of Dictyophora indusiata polysaccharide. The results showed that there were no significant changes in molecular weight, functional groups and surface morphology after the in vitro dynamic simulated digestion, indicating that D. indusiata polysaccharide maintained a relatively stable structure during the dynamic in vitro salivary-gastrointestinal digestion. In addition, D. indusiata polysaccharide improved the abundance of beneficial bacteria, including Blautia, Coprobacter and Fusicatenibacter. It is remarkable that D. indusiata polysaccharide significantly increased the level of acetic acid and propionic acid. In conclusion, these results suggested that D. indusiata polysaccharide was a potential source of prebiotics, which provides a basis for the development of D. indusiata polysaccharide in the food or medical field.

Transformation of dissolved organic matter leached from biodegradable and conventional microplastics under UV/chlorine treatment and the subsequent effect on contaminant removal

The ultraviolet (UV)/chlorine process has been widely applied for water treatment. However, the transformation of microplastic-leached dissolved organic matter (MP-DOM) in advanced treatment of real wastewater remains unclear. Here, we investigated alterations in the photoproperties of MP-DOM leached from biodegradable and conventional microplastics (MPs) and their subsequent effects on the degradation of sulfamethazine (SMT) by the UV/chlorine process. Spectroscopy was used to assess photophysical properties, focusing on changes in light absorption capacity, functional groups, and fluorescence components, while photochemical properties were determined by calculating the apparent quantum yields of reactive intermediates (ΦRIs). For photophysical properties, our findings revealed that the degree of molecular structure modification, functional group changes, and fluorescence characteristics during UV/chlorine treatment are closely linked to the type of MPs. For photochemical properties, the ΦRIs increased with higher chlorine dosages due to the formation of new functionalities. Both singlet oxygen (1O2) and hydroxyl radicals (•OH) formation were strongly correlated with excited triplet state of DOM (3DOM*) in the UV/chlorine treatment. Additionally, we found that the four types of MP-DOM inhibit the degradation of SMT and elucidated the mechanisms behind this inhibition. We also proposed degradation pathways for SMT and assessed the ecotoxicity of the resulting intermediates. This study provides important insights into how the characteristics and transformation of MP-DOM affect contaminant degradation, which is critical for evaluating the practical application of UV-based advanced oxidation processes (UV-AOPs).

The diversity and biogeography of bacterial communities in lake sediments across different climate zones

Bacteria are diverse and play important roles in biogeochemical cycling of aquatic ecosystems, but the global distribution patterns of bacterial communities in lake sediments across different climate zones are still obscure. Here we integrated the high-throughput sequencing data of 750 sediment samples from published literature to investigate the distribution of bacterial communities in different climate zones and the potential driving mechanisms. The obtained results indicated that the diversity and richness of bacterial community were notably higher in temperate and cold zones than those in other climate zones. In addition, the bacterial community composition varied significantly in different climate zones, which further led to changes in bacterial functional groups. Specifically, the relative abundance of nitrogen cycling functional groups in polar zones was notably higher compared to other climate zones. Regression analysis revealed that climate (mean annual precipitation, MAP; and mean annual temperature, MAT), vegetation, and geography together determined the diversity pattern of sediment bacterial community on a global scale. The results of partial least squares path modeling further demonstrated that climate was the most significant factor affecting the composition and diversity of bacterial communities, and MAP was the most important climate factor affecting the composition of bacteria community (R2 = 0.443, P < 0.001). It is worth noting that a strong positive correlation was observed between the abundance of the dominant bacterial group uncultured_f_Anaerolineaceae and the normalized difference vegetation index (NDVI; P < 0.001), suggesting that vegetation could affect bacterial community diversity by influencing dominant bacterial taxa. This study enhances our understanding of the global diversity patterns and biogeography of sediment bacteria.

Effects of Ageing on Surface Properties of Biochar and Bioavailability of Heavy Metals in Soil

This study aims to explore the effects of biochar ageing on its surface properties and the bioavailability of heavy metals in soil. The biochar was subjected to chemical oxidation/dry–wet cycles (CDWs), chemical oxidation/freeze–thaw cycles (CFTs), and natural ageing (NT) to analyze changes in the elemental composition, pH, specific surface area, pore volume, and surface functional groups. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were applied to characterize the functional groups and microstructure, and the BCR sequential extraction method was employed to demonstrate the fractionation distribution of Cu, Cd, and Pb. The results showed that the CDWs and CFTs treatments significantly reduced the carbon content of the biochar (with a maximum reduction to 47.70%), increased the oxygen content (up to 49.17%), and notably increased the specific surface area and pore volume. The pH decreased significantly from 9.91 to 4.92 and 4.99 for the CDWs and the CFTs, respectively. The FTIR analysis indicated notable changes in hydroxyl and carboxyl functional groups, and the SEM revealed severe microstructural damage in biochar after the CDWs and CFTs treatments. The heavy metal fractionation analysis indicated that exchangeable Cu, Cd, and Pb significantly increased after the CDWs treatment, reaching 31.40%, 5.25%, and 6.79%, respectively. In conclusion, biochar ageing significantly affects its physicochemical properties and increases the bioavailability of heavy metals, raising concerns about its long-term remediation effectiveness.

Effects of antioxidants on chemical and rheological properties of asphalt binders from different crude oil sources

Antioxidants can effectively mitigate or delay the oxidative aging degradation of asphalt binder, thereby improving pavement durability. While research has largely concentrated on the application of antioxidants to asphalt binders from a single source, limited studies have explored their effects on binders derived from different crude oil sources. Moreover, the relationship between the chemical and rheological properties of antioxidant-modified asphalt binders remains insufficiently understood. In this study, three antioxidants - zinc diethyldithiocarbamate (ZDC), Irganox 1010 and kraft lignin - were utilized and blended with base binders sourced from three distinct regions globally. Fourier transform infrared spectroscopy (FTIR) was utilized to analyze the impact of these antioxidants on the chemical composition of aged binders. Additionally, dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were conducted to assess the high- and low-temperature performance of the antioxidant-modified binders, identifying the most effective antioxidant. The linear amplitude sweep (LAS) test further evaluated the performance of ZDC across binders from different crude oil sources. The results revealed three key findings: first, chemical functional group changes due to antioxidants are not always reflected in rheological performance; second, ZDC demonstrated superior performance across different base binders, as evidenced by improved aging indices, high-temperature rutting resistance, and enhanced fatigue and low-temperature cracking resistance; and third, asphalt binders from different crude oil sources exhibit varying sensitivities to antioxidant type and dosage. This study underscores the necessity of determining optimal antioxidant dosages for different asphalt binders, as the relationship between antioxidant dosage and effectiveness is not straightforward.

Sustainable biofuels from corncobs: optimization of microwave pretreatment for enhanced fermentable sugar yield

Microwave-Assisted Alkali (MAA) pretreatment of corncob biomass was optimized for maximum fermentable sugar yield using dilute sulfuric acid hydrolysis. A Central Composite Design (CCD) investigated the effects of microwave power (450–9000 W), NaOH concentration (1.5 to 4.5% wt./v), and irradiation time (10–20 min) on lignin removal. The optimal MAA pretreatment conditions were found to be 691.73 W, 3.4% NaOH, and 15.5 min, resulting in the selective removal of 73.36% lignin with high retention of cellulose (71.69%) and hemicellulose (22.14%). Characterization techniques (FTIR, SEM, XRD, TGA) confirmed substantial changes in surface morphology, functional groups, crystallinity, and thermal stability of the pretreated corncobs. Dilute sulfuric acid hydrolysis (0.5–2.5%, 110130 °C, 3060 min) of the optimized sample yielded a maximum reducing sugar output of 537.42 mg/g, achieved at 0.534% H2SO4, 122.3 °C, for 58 min. Optimizing Microwave-Assisted Alkali pretreatment process for corncobs could boost biofuel production efficiency, sustainably utilize agricultural waste, and advance a more sustainable energy landscape.