Changes In Functional Groups Research Articles

Recent advances in clay minerals for groundwater pollution control and remediation.

Clay minerals are abundant on Earth and have been crucial to the advancement of human civilization. The ability of clay minerals to absorb chemicals is frequently utilized to remove hazardous compounds from aquatic environments. Moreover, clay-based adsorbent products are both environmentally acceptable and affordable. This study provides an overview of advances in clay minerals in the field of groundwater remediation and related predictions. The existing literature was examined using data and information aggregation approaches. Keyword clustering analysis of the relevant literature revealed that clay minerals are associated with groundwater utilization and soil pollution remediation. Principal component analysis was used to assess the relationships among clay mineral modification methods, pollutant properties, and the Langmuir adsorption capacity (Qmax). The results demonstrated that pollutant properties affect the Qmax of pollutants adsorbed by clay minerals. Systematic cluster analysis was utilized to classify the collected data and investigate the relationships. The pollution adsorption mechanism of the unique structure of clay minerals was investigated based on the characterization results. Modified clay minerals exhibited changes in surface functional groups, internal structure, and pHpzc. This review provides a summary of recent clay-based materials and their applications in groundwater remediation, as well as discussions of their challenges and future prospects.

Effects of Aqueous Solution and Immersion Duration on Spontaneous Combustion Characteristics of Weakly Caking Coal

ABSTRACT Coal spontaneous combustion (CSC) severely affects the development of the coal industry and threatens the safety of coal miners. This study investigated how immersing coal in aqueous solution affects the CSC risk and evaluated the effect of the immersion duration. Fourier transform infrared spectrometry and thermogravimetric−differential scanning calorimetry analysis were performed. Coal samples were immersed in water from an underground coalmine or in distilled water for 30 or 60 days. Changes in microscopic functional groups and thermokinetic behaviors were determined. Immersion in distilled water for 60 days led to 4.41%, 2.26%, and 6.25% smaller masses of C=O, –CH3, and free hydroxyl groups, respectively, relative to their levels in raw coal. Additionally, the characteristic temperatures T 4 , T 5 , and T 6 were 8.8%, 9.0%, and 9.2% lower, respectively, and the average apparent activation energy was 15.67% lower. Immersion in water from an underground coalmine for 60 days led to 5.68%, 2.58%, and 6.54% higher masses of C=O, –CH3, and free hydroxyl groups, respectively, and 12.8%, 13.0%, and 13.5% higher characteristic temperature, respectively; the average apparent activation energy was 20.43% lower. These findings suggest that the coal immersed in water from an underground coalmine was the most susceptible to CSC.

Consecutive Fertilization-Promoted Soil Nutrient Availability and Altered Rhizosphere Bacterial and Bulk Fungal Community Composition

Fertilization is an important measure to quickly supplement the soil nutrients required for plantation productivity. However, the response patterns of the microbial community and functional taxa in Larix plantation root, rhizosphere, and bulk soil to short-term and consecutive fertilization have rarely been reported. In this study, we assessed Larix root, rhizosphere, and bulk soil microbial community on days 0, 5, 15, and 30 after the first inorganic fertilization and after three consecutive years of fertilization. The bacterial 16S and fungal ITS high-throughput sequencing technology were used to monitor changes in microbial community composition and potential functional groups, as well as changes in soil nutrient content and enzyme activity to evaluate the status of plantation soil productivity. Consecutive fertilization treatment significantly increased the available nitrogen, phosphorus, and potassium (NPK) content and soil enzyme activity. The nonmetric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) results showed that there were significant differences in microbial community composition in root samples, rhizosphere soil, and bulk soil samples. The dominant microbial taxa were different between root and soil microbial community composition. Consecutive fertilization treatment had little effect on endophytic microbial community but significantly increased the abundance of Gaiellales in rhizosphere soil and Mortierella in bulk soil. The redundancy analysis (RDA) and co-occurrence network analyses showed that Gaiellales and Mortierellales had significant positive correlations with soil nutrient content and enzyme activity. The fungal functional group compositions were significantly affected by consecutive fertilization treatment and the proportions of ectomycorrhizal and saprotroph significantly decreased, but the proportion of endophyte significantly increased in bulk soil samples. Our results suggested that consecutive fertilization may promote soil nutrient availability by increasing the abundance of Gaiellales and Mortierella. Consecutive fertilization maintained the balance of the soil microbiota under Larix plantation and had a positive effect on promoting soil nutrient availability. This study provided a theoretical basis for consecutive fertilization to promote soil nutrient availability through specific microbial groups.

Plant, insect, and soil microbial communities vary across brome invasion gradients in northern mixed‐grass prairies

Species interactions shape native plant communities, influencing both composition and ecosystem processes, with invasion by non‐native species threatening these dynamic relationships, native species, and function. The consequences of invasive plants in particular may stretch across taxa to impact plant, insect, and soil microbial communities directly and indirectly, with consequences for ecological functioning. In northern mixed‐grass prairies in the United States, invasion by two annual brome grasses, Bromus arvensis and B. tectorum, negatively impacts rangeland plants; however, the simultaneous effects on insects and soil microbes (bacteria and archaea), and the implications for ecological function, have received less attention. Here, using observational field studies conducted at two mixed‐grass prairie sites in Montana and Wyoming, we assessed the relationships between plants, insects, and soil microbes across gradients of invasion by B. arvensis and B. tectorum. Overall, we found differences in plant and insect communities and functional groups with increasing invasion abundance for both brome species. However, associations between invasion and the soil microbial community were species specific, as we only saw these relationships under B. tectorum invasion, implying B. tectorum may have more substantial consequences for rangeland management. While invasion by annual bromes may cause changes in certain plant and insect functional groups, such as C4 perennial grasses and certain insect herbivores, soil microbial functional groups may be less impacted, especially under B. arvensis invasion. This work sheds light on the need to explore changes in natural communities across taxa and to all invasive species, as ecosystem effects are likely to be contingent upon both.

Novel ethylene scavenger based on sillimanite and bentonite clay for packaging applications: A sustainable alternative for preservation of fresh produce

Natural and chemical-free material in food packaging applications has gained interest globally with increasing demand for human health and environmental concerns. The present research aimed to develop a mineral and clay-based ethylene scavenger by mixing Sillimanite (Al2SiO5) and Bentonite (Al2H2O6Si) at different ratios to protect the deterioration of fruits and vegetables. The samples were prepared in different proportions of Sillimanite and Bentonite on a weight basis and named SL/BT (100:0), SL/BT (80:20), SL/BT (70:30), and SL/BT (50:50). The ethylene adsorption capacity of the samples was studied for 21 days under three conditions, i.e., 29±3 °C and 55 ± 3% RH, 25 °C and 75 ± 2% RH, 55 °C, and 99 ± 1% RH. The scanning electron microscopy (SEM) result determines the average particle size of sillimanite (80–100 nm) and bentonite (80–110 nm. Brunauer-Emmett-Teller (BET) result shows the surface area and pore volume of the sillimanite (8.42 m2/g and 0.039 cc/g) and bentonite (20.765 m2/g, 0.073 cc/g), higher surface area and pore volume result in higher ethylene adsorption. FTIR was performed to analyze the functional group changes after ethylene adsorption. The samples kept at 29±3 °C and 55 ± 3% RH showed the highest ethylene adsorption capacity of 84%. From the above study, the mineral clay-based material can effectively enhance the shelf life of fruits and vegetable packaging.

Transient chemical and structural changes in graphene oxide during ripening

Graphene oxide (GO)—the oxidized form of graphene—is actively studied in various fields, such as energy, electronic devices, separation of water, materials engineering, and medical technologies, owing to its fascinating physicochemical properties. One major drawback of GO is its instability, which leads to the difficulties in product management. A physicochemical understanding of the ever-changing nature of GO can remove the barrier for its growing applications. Here, we evidencde the presence of intrinsic, metastable and transient GO states upon ripening. The three GO states are identified using a π−π*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi -{\\pi }^{*}$$\\end{document} transition peak of ultraviolet–visible absorption spectra and exhibit inherent magnetic and electrical properties. The presence of three states of GO is supported by the compositional changes of oxygen functional groups detected via X-ray photoelectron spectroscopy and structural information from X-ray diffraction analysis and transmission electron microscopy. Although intrinsic GO having a π−π*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pi -{\\pi }^{*}$$\\end{document} transition at 230.5 ± 0.5 nm is stable only for 5 days at 298 K, the intrinsic state can be stabilized by either storing GO dispersions below 255 K or by adding ammonium peroxydisulfate.

Evolution of Rheological and Microscopic Properties of Asphalt Binders under Fuel Corrosion

Vehicle fuel leaks can adversely affect the performance of asphalt pavements. To study the mechanisms of fuel corrosion damage in asphalt, four asphalt binders were selected in this study, and the evolution of their rheological and microscopic properties was investigated. Fuel corrosion caused continuous mass loss in asphalt binders. Base asphalt lost more than 50% of its mass after 24 h of fuel corrosion, while modified asphalts had better resistance. According to dynamic shear rheometer tests and multiple stress creep recovery tests, modifiers improved the high-temperature rheological properties of these asphalt binders. As the degree of fuel corrosion deepened, the indexes characterizing the high-temperature performance deteriorated. Rubber-modified asphalt showed the best resistance to high-temperature deformation, while the performance of LDPE-modified asphalt was more stable. In contrast, fuel corrosion improved the resistance of asphalt binders to low-temperature cracking to some extent: the creep strength (S) decreased as the creep rate (m) increased, and the resistance of SBS-modified asphalt to low-temperature cracking was optimal, with a 36% decrease in S-value after 24 h of fuel corrosion. Fourier transform infrared spectroscopy tests showed that diesel corrosion was a process of this physical dissolution, with no change in the chemical functional groups. Meanwhile, by using fluorescence images and analyzing the four-component test results, we found that fuel corrosion disrupted the stabilized structure formed by the modifiers, and the heavy components in the asphalt binders were converted into light components. This study reveals the evolution of the rheological and microscopic properties of asphalt under fuel corrosion, which can provide a reference for the optimization of fuel corrosion resistance in asphalt pavement.

Quantitative analysis on chemical influence of modified activated carbon in TSA/PSA for methanol via alterable phosphorus functional groups and stable structure

Volatile organic compounds (VOCs) emissions cause serious health problems and environmental pollution, and modified activated carbon is widely used in the treatment of VOCs pollution. Methanol was selected as adsorbate and activated carbon with alterable phosphorus functional groups was synthesized as adsorbent. In the absence of the influence of the physical properties, the chemical functional groups influence coefficient (AC) was proposed, which can be used to analysis and predict the influence of chemical functional groups specially. The results show that the performances including adsorption capacity and enrichment ratio are positively related to the AC whether in temperature swing adsorption (TSA) or pressure swing adsorption (PSA). By comparison, the adsorption capacity of PSA is greater than that of TSA because of the higher efficiency caused by faster cycle. Further research on process showed that the curve character of TSA, including breakthrough time and equilibrium time, is highly related with AC, but the curve character of PSA is mainly depended on the state of activated carbon. Therefore, the attenuation of TSA is mainly caused by the change of chemical functional groups, while the attenuation of PSA is mainly caused by the failure of activated carbon.

Investigation of the mechanism of solvothermal extraction of direct coal liquefaction residue by macromolecular models

Direct coal liquefaction residue (DCLR) is an industrial by-product from the direct coal liquefaction process. It has the unique characteristics of high carbon, high sulfur and high ash content, strong cohesiveness and low softening point, which makes DLCR a potential raw material. However, direct discharge of untreated DCLR can cause severe damage to environment and human body. Thus it is of great importance to utilize DCLR properly. In this study, solvothermal extraction of direct coal liquefaction residue (DCLR)was treated with N-methyl-2-pyrrolidone (NMP) and 1-methyl naphthalene (1-MN). In addition, molecular models of DCLR and two hypercoals (HPC: NMP-HPC, MN-HPC) were built to clarify the extraction mechanism, aiming to provide a technically feasible route to utilize DCLR and investigate the adaptation between extractant and raw materials. The structural parameters were obtained by means of industrial and elemental analysis, 13C NMR, XPS and FTIR. Subsequently, macromolecular structure models were constructed, with simulated molecular formulas C153H108N2O10S, C206H168N6O7 and C278H202N2O13S, respectively. After modifying the macromolecular models by Materials Studio for geometric optimization, annealing dynamics calculation, density simulation and analysis of chemical bonds and charge layout, these models reflected the macromolecular structural characteristics precisely. On the other hand, DCLR model underwent significant changes in functional groups, branched chain length and quantity pre and post solvothermal extraction, indicating that the thermal extraction process was mainly affected by swelling behavior and pyrolysis. Meanwhile the principles of the two extractants were also different.1-MN extraction was a heat-induced relaxation, while NMP extraction was heat & solvent-induced relaxation process. This study will be helpful in expanding the utilization of DCLR and understanding of mechanism of solvothermal extraction on the macromolecular level based on modeling.

Alternative Linkage Chemistries in the Chemoenzymatic Synthesis of Microviridin-Based Cyclic Peptides.

Engineering biosynthetic pathways to ribosomally synthesized and post-translationally modified peptides (RiPPs) offers several advantages for both in vivo and in vitro applications. Here we probe the ability of peptide cyclases to generate trimacrocycle microviridin analogs with non-native cross-links. The results demonstrate that diverse chemistries are tolerated by macrocyclases in the ATP-grasp family and allow for the construction of unique cyclic peptide architectures that retain protease inhibition activity. In addition, cocomplex structures of analogs bound to a model protease were determined, illustrating how changes in functional groups maintain peptide conformation and target binding.

A molecular dynamics simulation study on the recovery performance of aged asphalt binder by waste vegetable oil rejuvenators

This study employed molecular dynamics to simulate the recovery performance of a waste vegetable oil rejuvenator on aged asphalt binder. The model's accuracy was verified through density and glass transition temperature (Tg) calculations. The Radial Distribution Function (RDF) was utilized to assess the aggregation state of different asphalt binder components. The impact of the waste vegetable oil rejuvenator on asphalt binder microstructure was evaluated using cohesive energy density (CED), relative concentration, mean square displacement (MSD), radius of gyration (Rg), and free volume amount. Changes in functional groups of the aged and recycled asphalt binder samples were analyzed using Fourier transform infrared spectroscopy (FT-IR). Results indicate that the rejuvenator significantly influences the dispersion of SARA components. Improved compatibility between aged and virgin asphalt binders is achieved through increased activity of asphaltenes and resins. The incorporation of rejuvenators into asphalt binder mildly counters the aggregation of asphalt binder molecular structure, mitigates the negative effects of aging, and restores asphalt binder structure. The rejuvenator, enriched with polar groups as per FT-IR tests, increases the proportion of polar groups in the recycled asphalt binder. The recycled asphalt binder exhibits a higher proportion of polar molecules, and the rejuvenator reacts with the polar molecules in the asphalt binder at high temperatures.

Changes in Functional Groups and Crystal Structure of Coal Tar Pitch with Respect to Carbonization Temperature

In this study, changes in the microstructure of coal-tar pitch (CTP) during successive processes, including pyrolysis, polycondensation, and crystallization, were examined in connection with the resulting variations in structure factors, as measured by X-ray diffraction (XRD) analysis, and functional groups, as confirmed by Fourier transform infrared (FTIR) spectroscopy. To this end, four zones were defined based on variations in crystallinity, which were indicated by d002 and Lc. Each zone was further characterized by interpreting crystallinity development in relation to changes in functional groups and specimen height. At around 400 °C, polycondensation occurred as the C-Har and C-Hal peaks decreased in intensity. These peak reductions coincided with the formation of mesophase spheres, resulting in enhanced crystallinity. Subsequently, at around 500 °C, the peak intensity of C-H and COOH decreased, which was attributed to the release of large amounts of gases. This led to sharp volume changes and a temporary reduction in crystallinity. All these results suggest that changes in the functional groups of CTP at lower temperatures (600 °C or less) during the carbonization process are closely associated with variations in its crystallinity. The major findings of the present study provide valuable insights for designing highly effective processes in the manufacturing of synthetic graphite blocks using CTP as a binder material, including by selecting appropriate temperature ranges to minimize volume expansion and crystallinity degradation and determining the lowest possible carbonization temperature to ensure adequate binder strength.

Screening of West Cameroonian edible plant-based mucilage for the production of improved protein-polysaccharide conjugates

In developing countries, blending the powders of locally utilized edible plants for mucilage extraction can be a way to address the growing demand for more viscous and soluble cost-effective hydrocolloids. This study aimed to identify mucilaginous edible plants exploited in the western region of Cameroon in order to enhance the viscosity and water solubility of their mucilages. A semi-administered questionnaire facilitated a comprehensive ethno-nutritional survey. Powders (200 μm) from mucilaginous plants available were defatted, oven dried, and used to produce crude extracts in a water bath (50 °C, 1 h, 2 cycles), with distilled water (1:10, m/v), followed by triple filtration (60 μm, 25 °C) and double centrifugation (2900 g, 20 min). The apparent viscosity of these crude extracts was recorded (spindle 2#, 600 s−1, 60 rpm) at 25 °C, and compared to a 0.2% (m/v) xanthan gum solution (in distilled water). The best plant powders were blended (5 blends) for use under an alkaline condition (pH 10, 0.025 M) for optimal liquid mucilage production and its corresponding powder named hibisanua, derived by coagulating the liquid mucilage (4 °C, 96% ethyl alcohol), oven drying (45 °C), powdering, and sieving (200 μm). Some rheological parameters were determined. FTIR and SEM analysis were carried out with the mucilage hibisanua. Out of 300 surveyed participants, 120 (40%) from 17 ethnicities use the identified plants. Thirty species were found, spanning 27 genera and 19 botanical families. Hibiscus esculentus (okra) pods, Triumfetta annua (nkui) bark, and Corchorus olitorius (lalo) leaves are commonly used in traditional food processing. However, only okra (9.23 Pa s) and nkui (5.54 Pa s) liquid mucilage viscosities were similar to xanthan, making their defatted powders interesting. The validated plant powder mixture (F2) thus comprised 10% nkui and 90% okra (w/w). Their crude extract of concentration 1.51% (w/v) showed the highest dynamic viscosity (23.05 Pa s), not significantly different (p ≥ 0.05) from the control. The resulting dry mucilage with a yield of 215.8 mg/g F2 had the highest solubility (83.05%) with a specific viscosity of 11.519 Pa s upon a desirability of 0.73. All polysaccharides’ solutions exhibited pseudoplastic characteristics and shear-thinning behaviour. A concentrated solution (1.51%) of hibisanua had a rheologic index (0.742) and viscous relaxation time (69.25 s) comparable to xanthan gum. Its structural analysis revealed functional group and morphological changes, typical of highly physical gelling pectic mucilages. These findings support the formulated plant powder approach and the use of its mucilage in the food and pharmaceutical industries.

The hidden depths of forest soil organic carbon chemistry in a pumice soil

Forest ecosystems can store massive amounts of organic carbon (OC) deep in their soils. Soil OC (SOC) is composed of several complex organic compounds of which groupings of these organic compounds can provide an insight into evaluating the formation and fate of SOC. However, there is little information available regarding the chemical composition of deep forest SOC and how they compare to upper soil depths. The objective of this study was to explore the SOC chemistry changes with increasing soil depth on a fine spatial scale in a planted forest soil derived from young volcanic erupted airfall deposits. Soil core samples to 1 m depth were collected from Puruki Experimental Forest (New Zealand) and examined for incremental depth changes in SOC functional groups, or chemical shift regions, using solid-state 13C cross polarisation magic angle spinning nuclear magnetic resonance (13C CPMAS-NMR) spectroscopy. The results showed that soil depth was a driver of change in soil chemical shift regions. The presence of a coarse-textured soil horizon, lapilli layer, at depth was a driver of significant (p < 0.05) differences between SOC functional groups. In the upper soil profile (0–10 cm), the chemical shift distribution was dominated by O-alkyl C (39%) followed by alkyl C (32%), aromatic C (23%), and carboxyl C (6%). In the deep soil layers, we found alkyl C increased below the lapilli layer (varying depth > 50 cm) compared to above the lapilli layer. In the deep soil layers the alkyl C was the dominant functional group (55%), followed by O-alkyl C (28%). Furthermore, there was a decrease at depth in aromatic (12%) and carboxyl C (5%). The A/O-A ratio increased with depth from soil above the lapilli layer compared to soils below the lapilli layer indicating a greater degree of organic matter decomposition and a corresponding decrease in the labile OC fractions. Within the lapilli layer the SOC functional groups and A/O-A ratio were highly variable. These results highlight that changes in SOC chemical composition occur with increasing soil depth, a property of deep soil that is frequently understudied, and are highly influenced by the multi layered nature of soil derived from volcanic airfall deposits.

Formulation and Evaluation of Teneligliptin Nanosuspension

In this present study, the drug Teneligliptin is selected for the management of Type-2 Diabetes mellitus. The drug-excipient compatibility study results showed that there is no chemical change occur between the drug and the excipients and there was no functional group change observed. Teneligliptin is poorly water-soluble drug and it was fabricated as nanosuspension of Nine formulations by using nano precipitation technique. In this method, nano size particle size of Teneligliptin was obtained by using different type of various proportions of stabilizers along with other ingredient at different stirring speed. For the prepared formulation (F1-F9) the particle size, polydispersibility index and zeta potential were done. Among nine formulations, formulation 8(F8) results revealed that the values are desirable and stable. The total drug content of all the formulation ranges from 81% to 99%, The average particle size of F1 to F9 batches was found to be in the range of 0.211 nm to 0.486 nm The scanning electron microspore study stated that the nano size particles were spherical in shape. Among all the formulations (F8) was optimized which showed maximum highest percentage of drug release at 24 hours. The cumulative percentage of drug release of formulation 8 (F8) increase with the optimum concentration of stabilizers and tween 80. The release rate of optimized formulation 8(F8) was fitted with various release kinetic studies and the selected formulation followed zero order kinetics. The results of stability study was confirmed that the prepared Teneligliptin nanosuspension is stable during the stability study. Thus, it can be concluded that the nanosuspension method was commercially feasible and cost effective.

Investigation of Roughness, Morphology, and Wettability Characteristics of Biopolymer Composite Coating on SS 316L for Biomedical Applications.

This project aims to create a 316L stainless steel coated with a biocomposite based on chitosan for use in the biomedical industry. To completely coat the material, the dip-coating technique was used to apply plain chitosan, chitosan nanosilver, chitosan biotin, and chitosan-nanosilver-biotin in that order. This coating's surface morphology was investigated with field emission scanning electron microscopy (FESEM). Surface roughness, average size distribution, and 2D and 3D surface tomography were all investigated using scanning probe microscopy and atomic force microscopy (SPM and AFM). The Fourier transform infrared (FTIR) spectroscopy technique was used to quantify changes in functional groups. To evaluate the coated samples' wettability, contact angle measurements were also performed. The chitosan (CS) + nanosilver, CS + biotin, and CS + biotin + nanosilver-coated 316L stainless steel showed roughness values of about 8.68, 4.21, and 3.3 nm, respectively, compared with the neat chitosan coating, which exhibits 12 nm roughness, indicating a strong effect of biotin and nanosilver on surface topography whereas the coating layers were homogenous, measuring around 33 nm in thickness. For CS + nanosilver and CS + biotin, the average size of agglomerates was approximately 444 nm and 355 nm, respectively. The coatings showed adequate wettability for biomedical applications, were homogeneous, and had no cracks. Their contact angles were around 51-75 degrees. All of these results point to the composite coating's intriguing potential for use in biological applications.

Tuning membrane properties to control supersaturation of antisolvent crystallization

The crystal morphology influences the properties of organic compounds, especially in pharmaceutics such as the dissolution and absorption of drugs in the human cells. In antisolvent crystallization, the crystal size and shape are tied to the degree of mixing and dosage of antisolvent, which could be controlled using membranes with specific morphology/surface properties. Little is known though on the relationship between membrane characteristics, antisolvent mass transfer and crystal properties. Flat sheet polyvinylidene fluoride (PVDF) membranes were prepared using non-solvent induced phase separation, to illustrate the impact of membrane characteristics on the resulting crystal size distribution (CSD) obtained using membrane-assisted antisolvent crystallization (MAAC). The crystallization of glycine was taken as case study. We showed the antisolvent transmembrane flux increased when the membrane thickness decreased, or when the hydrophobicity or the porosity increased. After MAAC operation, membranes had no significant change in surface functional groups, hydrophobicity nor structure. The best-performing membrane was found to have 119° hydrophobicity, 89.4 % porosity and 140 μm thickness, reaching high reproducibility of CSD corresponding to stable transmembrane fluxes throughout 180 min of operation. The capacity of MAAC to consistently produce a narrow CSD at optimum membrane characteristics makes this technology very competitive with conventional crystallization processes.

Evaluation of the application of chemically adapted gourd fibre in polyester composite fabrication

Purpose Gourd fibres (GF) are a natural biodegradable fibre material with excellent mechanical properties and high tensile strength. The use of natural fibres in composite materials has gained popularity in recent years due to their various advantages, including renewability, low cost, low density and biodegradability. Gourd fibre is one such natural fibre that has been identified as a potential reinforcement material for composites. However, it has low surface energy and hydrophobic nature, which makes it difficult to bond with matrix materials such as polyester. To overcome this problem, chemically adapted gourd fibre has been proposed as a solution. Chemical treatment is one of the most widely used methods to improve the properties of natural fibres. This research evaluates the feasibility and effectiveness of incorporating chemically adapted gourd fibre into polyester composites for industrial fabrication. The purpose of this study is to examine the application of chemically modified GF in the production of polyester composite engineering materials. Design/methodology/approach This work aims to evaluate the effectiveness of chemically adapted gourd fibre in improving the adhesion of gourd fibre with polyester resin in composite fabrication by varying the GF from 5 to 20 wt.%. The study involves the preparation of chemically treated gourd fibre through surface modification using sodium hydroxide (NaOH), permanganate (KMnO4) and acetic acid (CH3COOH) coupling agents. The mechanical properties of the modified fibre and composites were investigated. It was then characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) to determine the changes in surface morphology and functional groups. Findings FTIR characterization showed that NaOH treatment caused cellulose depolymerization and caused a significant increase in the hydroxyl and carboxyl groups, showing improved surface functional groups; KMnO4 treatment oxidized the fibre surface and caused the formation of surface oxide groups; and acetic acid treatment induced changes that primarily affected the ester and hydroxyl groups. SEM study showed that NaOH treatment changed the surface morphology of the gourd fibre, introduced voids and reduced hydrophilic tendencies. The tensile strength of the modified gourd fibres increased progressively as the concentration of the modification chemicals increased compared to the untreated fibres. Originality/value This work presents the designed composite with density, mechanical properties and microstructure, showing remarkable improvements in the engineering properties. An 181.5% improvement in tensile strength and a 56.63% increase in flexural strength were got over that of the unreinforced polyester. The findings from this work will contribute to the understanding of the potential of chemically adapted gourd fibre as a reinforcement material for composites and provide insights into the development of sustainable composite materials.

Quantifying effects of surface morphology and functional groups of carbon fibers on mass transfer coefficient in vanadium redox flow batteries

Optimization of porous electrodes has emerged as a fascinating alternative to improve the power density of redox flow batteries. While numerous studies have demonstrated the significant reduction in overpotentials due to electrode modifications, there has yet to be research that elucidates the underlying mechanism. The developed fitting model in the present study enables efficient mass transfer coefficient characterization for redox flow battery systems with sluggish reactants. Based on the newly proposed fitting model and experimental data, the present study explores the mechanism of how changes in electrode morphology and functional groups affect the mass transfer coefficient. It is found that micro-scale pores on the fiber surface, when fibers were thermally treated at 300 °C, successfully enhanced mass transfer of the reactants in the electrode likely owing to the shortened diffusion distance, while nano-scale pores, when fibers thermally treated at 400 °C, showed minor effects on mass transfer enhancement. Besides, the increment of the oxygen containing functional groups also enhanced the mass transfer rate in the diffusion layer likely attributable to the improved electrode hydrophilicity. Last, the power-law correlations for Sherwood number and Reynolds number for different electrode samples were established, enabling frontend screening in future's electrode development campaigns.

Insight into the dynamic transformation properties of microplastic-derived dissolved organic matter and its contribution to the formation of chlorination disinfection by-products.

Microplastics (MPs) can cause adverse effects and pose potential threats to humans and the environment. In addition, dissolved organic matter leached from MPs (MP-DOM) is also a critical issue due to its ecotoxicity and potential to form disinfection by-products (DBPs) during the disinfection process of water treatment plants. However, limited information is available on the dynamic transformation of MP-DOM during UV irradiation and subsequent disinfection, which may further influence the formation of DBPs in MP-DOM. Herein, PSMPs-DOM were leached in aqueous solutions under UV irradiation and the samples were then chlorinated. PSMPs-DOM before and after chlorination were characterized by multiple spectral technologies and methods. With prolonged irradiation time, the aromaticity, molecular weight, humic-like substances and oxygen-containing functional groups of PSMPs-DOM increased, suggesting the continuous transformation of PSMPs-DOM. After chlorination, the aromaticity, molecular weight and humic-like substances of PSMPs-DOM decreased, among which the changes of C2 and oxygen-containing functional groups were more significant. Besides, the PSMPs-DOM formed under prolonged irradiation exhibited higher chlorine reactivity, owing to the more aromatic structures and unsaturated bonds. TCM, DCBM, DBCM and TBM were detected in all chlorinated PSMPs-DOM samples, while the PSMPs-DOM formed at the later stage of irradiation exhibited lower THMs formation potential. The correlation results showed that the conversion of humic-like substances in PSMPs-DOM affected the THMs formation potential, with photo-induced humic-like substance being a more dominant factor. This study provided more information on the relationship between the compositional transformation of MP-DOM and their potential to form DBPs, which may facilitate the assessment of potential toxicity associated with MPs-containing water, as well as the development of more effective water treatment methods.