Environmental Compatibility Research Articles

Development of Technology for the Bioleaching of Uranium in a Solution of Bacterial Immobilization

This study presents findings regarding the kinetics of ferrous iron oxidation in solution mediated by Acidithiobacillus ferrooxidans bacteria within a continuous-flow bioreactor employing diverse types of immobilizers. The objective is to augment the rate of ferrous iron oxidation in solutions utilizing an immobilizer for Acidithiobacillus ferrooxidans strains. Immobilization represents a promising avenue for enhancing the efficiency of Fe2⁺ oxidation via acidophilic ferrooxidizing bacteria, leading to a several-fold increase in oxidation rate. A comparative analysis was conducted to evaluate the efficacy of different types of immobilizer in facilitating iron oxidation within a continuous-flow bioreactor, including the application of wood chips coated with Fe(OH)3. The results indicate that wood chips coated with iron hydroxide serve as effective type of immobilizer, facilitating the robust attachment of Acidithiobacillus ferrooxidans via electrostatic interactions between negatively charged bacteria and positively charged surfaces. Experimental investigations were conducted using novel immobilization matrices in pilot-scale tests simulating the underground borehole leaching (UBL) of uranium. The bioactivation of leaching solutions enhances the efficiency and environmental compatibility of UBL compared to conventional chemical oxidation methods. The relationships between redox potential and ferric iron content in bioactivated solutions during the UBL of uranium were delineated. The significance of this study lies in its elucidating the pivotal role of Fe2⁺ oxidation in uranium extraction processes, particularly in the context of UBL. By employing bioactivation mediated by Acidithiobacillus ferrooxidans, the study demonstrates not only enhanced uranium extraction efficiency, but also markedly improved environmental sustainability compared to traditional chemical oxidation methods. The findings reveal crucial correlations between redox potential and ferric iron concentration in bioactivated solutions.

Enhancing durability and sustainability of industrial floors: A comparative analysis of dry-shake surface hardeners

This study investigates the development of a cost-effective and sustainable dry-shake surface hardener for enhancing the durability of industrial concrete floors. Utilizing locally sourced materials, the research aimed at not only ensuring the hardener's strength and finish but also its economic viability and environmental friendliness. Fourteen unique mixtures were formulated by altering the sand ratios and incorporating superplasticizers to optimize the composition. These mixtures underwent rigorous testing over 7, 14, and 28 days, evaluating their compressive and flexural strengths, flowability, water absorption, and impact resistance. The findings revealed that the modified floor hardener, specifically the FH-12 mixture, exhibited superior performance across all tested parameters. It showed higher compressive and flexural strengths, enhanced impact resistance, and reduced water absorption compared to other variants and commercially available hardeners. Notably, the use of finer coarse sand and the adjustment of superplasticizer quantities significantly contributed to these outcomes. This breakthrough demonstrates the potential of employing locally available materials to create a durable, cost-effective, and environmentally friendly solution for industrial flooring. The study underscores the importance of material characterization and methodical formulation in developing construction materials that meet the dual criteria of performance and sustainability. This option is preferred for its lower environmental impact and compatibility with sustainable practices, contributing to Sustainable Development Goal 9 on industry, innovation, and infrastructure. It highlights the role of floor hardeners in global sustainability efforts.

Green proton reservoirs of PANI for disposable high-performance zinc-ion batteries

Rechargeable batteries are widely used to power various electronic devices. However, their toxic components cause serious environmental pollution when discarded. To date, the toxicity characteristics of rechargeable batteries do not meet the requirements for implantable medical devices. Herein, we report an organic cathode using tannin-protonated polyaniline (Tannin-PANI). As “green proton reservoirs”, plant-derived tannins continuously supply H+ to maintain high electrochemical activity and excellent reversibility of Tannin-PANI. Hence, the Tannin-PANI-based cathode exhibited a capacity of 92.8 mAh g−1 after 1500 cycles at 10.0 A g−1. Moreover, it demonstrated long-term stability for more than 10,000 cycles in bacterial cellulose-based gel electrolyte. Further, the Tannin-PANI-based cathode showed excellent in vitro biocompatibility, and a pouch cell composed of the Tannin-PANI electrode had no significant impact on plant growth. This study provides further insights into the design of implantable batteries with high stability, excellent biocompatibility, and high environmental compatibility.

Evaluation of asphalt film thickness and heavy metal leaching of oxidizing slag used as an aggregate material in dense-graded asphalt concrete.

Electric-arc-furnace (EAF) steelmaking uses scrap iron and steel as raw materials. Scrap iron and steel originate from complex sources and may contain heavy metal components which can leach into the environment over time due to wear-and-tear. A by-product of the EAF steelmaking process is oxidizing slag, and approximately 1.2 million metric tons is produced every year in Taiwan alone. This study investigated substitution of natural aggregates with oxidizing slag in dense-graded asphalt concrete. We evaluated the water resistance and asphalt film thickness of the oxidizing slag substituted asphalt concrete and further explored the performance of oxidizing slag as paving material. We determined the dissolved and total amounts of heavy metals in the oxidizing slag, comparing these results with current regulatory controls to assess the environmental compatibility of the oxidizing slag. We found that due to the complicated sources of oxidizing slag, the basic properties should be analyzed on a batch-to-batch basis. Furthermore, we recommend trial mixing before upscaling the production of oxidizing slag substituted dense-graded asphalt concrete to confirm the mixing time required to achieve uniformity. The results also show that in comparison to natural aggregates used in asphalt concrete, oxidizing slag exhibits superior performance in terms of increased asphalt film thickness and improved water resistance. Furthermore, oxidizing slag as an aggregate material was associated with decreased heavy metal leaching and reduced environmental pollution. The results of the toxicity characteristic leaching procedure (TCLP) met regulatory requirements. However, the microwave-assisted aqua-regia digestion procedure showed heavy metal concentrations exceeding the monitoring standards for food crops. Considering environmental compatibility, it is recommended that controlling the total amount of heavy metals in oxidizing slag should be included in regulatory requirements. Furthermore, we should prohibit the use of materials such as oxidizing slag and other steel furnace slag in the roadways adjacent to edible crop farmlands.

Enhanced mechanical endurance and power conversion efficiency in flexible Cu2ZnSnS4 solar cells using ZnO/Ag-Ag2O/ZnO film

Cu2ZnSnS4 (CZTS) solar cells occupy an important direction in the field of clean energy research due to their environmental friendliness, low cost, and industrial technology compatibility. The complex and variable usage environment also accelerates the development of flexible CZTS solar cells. However, the inferior flexibility of ITO films limited their development. ZnO/Ag/ZnO (ZAZ) films are potential choices for transparent conductive layers of CZTS solar cells due to their high transmittance, conductivity, and flexibility. To further enhance the photovoltaic performance and mechanical durability of ZAZ films and solar cells, Ag2O was introduced into ZAZ film by magnetron sputtering. An ultra-high average transmittance of 96.6% in 400–800 nm was achieved for ZnO/Ag-Ag2O/ZnO (ZAAZ) films at Ag2O sputtering power of 40 W, which was attributed to the fact that Ag2O effectively inhibited the growth of 3D islands of Ag film, and formed a more uniform Ag film. ZAAZ films offered a superior figure of merit value of 0.1041 Ω−1. The power conversion efficiency (PCE) of ZAAZ solar cells was 6.94%, higher than that of ZAZ solar cells (6.69%). Remarkably, the PCE of ZAAZ solar cells was 7.9% higher than that of ZAZ solar cells after 1000 bending cycles. Therefore, Therefore, this approach may provide a promising way to improve the photovoltaic performance and mechanical durability of flexible solar cells.

Exploiting Waste towards More Sustainable Flame-Retardant Solutions for Polymers: A Review.

The development of sustainable flame retardants is gaining momentum due to their enhanced safety attributes and environmental compatibility. One effective strategy is to use waste materials as a primary source of chemical components, which can help mitigate environmental issues associated with traditional flame retardants. This paper reviews recent research in flame retardancy for waste flame retardants, categorizing them based on waste types like industrial, food, and plant waste. The paper focuses on recent advancements in this area, focusing on their impact on the thermal stability, flame retardancy, smoke suppression, and mechanical properties of polymeric materials. The study also provides a summary of functionalization methodologies used and key factors involved in modifying polymer systems. Finally, their major challenges and prospects for the future are identified.

Organic Electrode Materials for Energy Storage and Conversion: Mechanism, Characteristics, and Applications.

ConspectusLithium ion batteries (LIBs) with inorganic intercalation compounds as electrode active materials have become an indispensable part of human life. However, the rapid increase in their annual production raises concerns about limited mineral reserves and related environmental issues. Therefore, organic electrode materials (OEMs) for rechargeable batteries have once again come into the focus of researchers because of their design flexibility, sustainability, and environmental compatibility. Compared with conventional inorganic cathode materials for Li ion batteries, OEMs possess some unique characteristics including flexible molecular structure, weak intermolecular interaction, being highly soluble in electrolytes, and moderate electrochemical potentials. These unique characteristics make OEMs suitable for applications in multivalent ion batteries, low-temperature batteries, redox flow batteries, and decoupled water electrolysis. Specifically, the flexible molecular structure and weak intermolecular interaction of OEMs make multivalent ions easily accessible to the redox sites of OEMs and facilitate the desolvation process on the redox site, thus improving the low-temperature performance, while the highly soluble nature enables OEMs as redox couples for aqueous redox flow batteries. Finally, the moderate electrochemical potential and reversible proton storage and release of OEMs make them suitable as redox mediators for water electrolysis. Over the past ten years, although various new OEMs have been developed for Li-organic batteries, Na-organic batteries, Zn-organic batteries, and other battery systems, batteries with OEMs still face many challenges, such as poor cycle stability, inferior energy density, and limited rate capability. Therefore, previous reviews of OEMs mainly focused on organic molecular design for organic batteries or strategies to improve the electrochemical performance of OEMs. A comprehensive review to explore the characteristics of OEMs and establish the correlation between these characteristics and their specific application in energy storage and conversion is still lacking.In this Account, we initially provide an overview of the sustainability and environmental friendliness of OEMs for energy storage and conversion. Subsequently, we summarize the charge storage mechanisms of the different types of OEMs. Thereafter, we explore the characteristics of OEMs in comparison with conventional inorganic intercalation compounds including their structural flexibility, high solubility in the electrolyte, and appropriate electrochemical potential in order to establish the correlations between their characteristics and potential applications. Unlike previous reviews that mainly introduce the electrochemical performance progress of different organic batteries, this Account specifically focuses on some exceptional applications of OEMs corresponding to the characteristics of organic electrode materials in energy storage and conversion, as previously published by our groups. These applications include monovalent ion batteries, multivalent ion batteries, low-temperature batteries, redox flow batteries with soluble OEMs, and decoupled water electrolysis employing organic electrodes as redox mediators. We hope that this Account will make an invaluable contribution to the development of organic electrode materials for next-generation batteries and help to unlock a world of potential energy storage applications.

Microfluidic electrochemical biosensors: tools for advancing the sustainable development goals

New technologies can help to achieve the sustainable development goals (SDGs) of the United Nations. We discuss the contribution of microfluidic electrochemical biosensors to advancing the SDGs. These sensors can be applied in various fields given their low cost, self-powering ability, environmental compatibility, ease of use, and small sample volume requirements.

Nature‐Inspired Halide Perovskite Breath Figures: Unleashing Enhanced Light‐Matter Interaction

AbstractHalide perovskites offer a transformative potential for optoelectronics through tailoring the light‐matter interactions at the nanoscale. However, their susceptibility to environmental factors and limited compatibility with standard lithography techniques present significant challenges in precise nanopatterning. This work unveils a nature‐inspired breath figures (BFs) approach to pattern halide perovskites and enhancing their optoelectronic performance. The fabrication of BFs based on BiI3 allows for changes in nanopore size (ranging from 247 to 423 nm) and their distribution. Subsequently, these BiI3 BFs are transformed into hybrid halide MA3Bi2I9 BFs using a vapor‐assisted technique while retaining the nanoporous topology of the BiI3 structure. The resultant MA3Bi2I9 BFs show significantly enhanced light absorption compared to conventional thin films, attributed to the increased extinction and lower refractive index. The optoelectronic performance of the MA3Bi2I9 BFs is showcased by constructing a photodetector, which exhibits three orders of magnitude higher responsivity and detectivity, up to 1 AW−1 and 1.3 × 1012 Jones, respectively, outperforming the photodetectors based on solution‐processed A3B2I9 halide perovskite thin films. The BFs method provides flexibility in tuning nanoscale morphology, showcasing its potential in advancing lead‐free optoelectronics and paving the way for next‐generation optoelectronic devices.

An Integrated Testing Strategy (ITS) to assess the environmental compatibility of wood protection techniques

To quantify the possible impact of different wood protection techniques on the aquatic environment, we applied a tiered Integrated Testing Strategy (ITS) on leachates obtained from untreated (UTW) Norway spruce (Picea abies), specimens treated with a copper-ethanolamine-based preservative solution, complying with the Use Class 3 (UC3), and specimens thermally modified (TM). Different maturation times in water were tested to verify whether toxicant leaching is time-dependent. Tier I tests, addressing acute effects on Aliivibrio fischeri, Raphidocelis subcapitata, and Daphnia magna, evidenced that TM toxicity was comparable or even lower than in UTW. Conversely, UC3 significantly affected all species compared to UTW, also after 30 days of maturation in water, and was not considered an environmentally acceptable wood preservation solution. Tier II (effects on early-life stages of Lymnea auricularia) and III (chronic effects on D. magna and L. auricularia) performed on UTW and TM confirmed the latter as an environmentally acceptable treatment, with increasing maturation times resulting in decreased adverse effects. The ITS allowed for rapid and reliable identification of potentially harmful effects due to preservation treatments, addressed the choice for a less impacting solution, and can be effective for manufacturers in identifying more environmentally friendly solutions while developing their products.

Effective removal of Rhodamine 6G (Basic Red-1) reactive dye using waxy corn starch in waste water of textile industry

The textile industry generates effluents containing toxic dyes, which have detrimental effects on the environment, including air, soil, and water contamination. These dyes also pose risks to human health and disrupt aquatic ecosystems. Developing ecological and cost-effective method to address this issue is a major challenge. This study focuses on utilizing waxy cornstarch, which exhibits unique properties such as high biodegradability, environmental compatibility, low sludge volume, small particle size, and high surface area (1.27 m2/g), for removing the reactive dye Rhodamine 6G (Basic Red-1) from textile wastewater. The composition of waxy cornstarch was analyzed, including determination of protein content using the Kjeldahl apparatus, as well as moisture content, ash content, and fine fiber content through experimental methods. The rate of dye removal from wastewater was assessed using a UV-spectrophotometer. The experimental design was selected, and trials were conducted using a glass testing apparatus. Dye removal rates were investigated at different dosages, temperatures, and pH ranges. The highest dye removal efficiency of 83.6% was achieved at a pH of 5, a temperature of 40 °C, and a coagulant dosage of 40 mg/l. These findings highlight the potential of waxy cornstarch as a natural coagulant for effective removal of Rhodamine 6G dye from textile wastewater.

Biochar from co-pyrolysis of biological sludge and woody waste followed by chemical and thermal activation: end-of-waste procedure for sludge management and biochar sorption efficiency for anionic and cationic dyes

Nine biochars were produced by co-pyrolysis of sawdust and biological sludge following the “design of experiment” approach. Two kinds of sludge (both deriving from the treatment of mixed industrial-municipal wastewater) and two types of woody waste were selected as categorical predicting variables, while contact time, pyrolysis temperature, and sludge percentage were used as quantitative variables. Biochars were analysed for their product characteristics and environmental compatibility based on the European Standards (EN 12915–1:2009) for materials intended for water treatment (i.e. ash content, water leachable polycyclic aromatic hydrocarbons (PAHs) and elements), as well as for specific surface area (SSA), using them as response variables of a multivariate partial least square multiple regression, whose results provided interesting insights on the relationships between pyrolysis conditions and biochar characteristics. Biochars produced with sludge and/or providing the highest SSA values (258–370 m2 g−1) were selected to undergo a sustainable chemical treatment using a by-product of the gasification of woody biomass, complying in all cases with European Standards and achieving therefore the end-of-waste status for sewage sludge. The biochar deriving from the highest percentage of sludge (30% by weight) and with the highest SSA (390 m2 g−1) was thermally activated achieving SSA of 460 m2 g−1 and then tested for the sorption of direct yellow 50 and methylene blue in ultrapure water and real wastewater, compared to a commercial activated carbon (AC). The biochar showed Langmuir sorption maxima (Qm) 2–9 times lower than AC, thus highlighting promising sorption performances. Qm for methylene blue in wastewater (28 mg‧g−1) was confirmed by column breakthrough experiments.

Sustainable strategies towards better utilization of synthetic polymers.

The abstract provides an overview of a study focused on analyzing diverse strategies to achieve sustainable utilization of synthetic polymers through effective waste management. The escalating global consumption of synthetic polymers has precipitated a concerning increase in plastic waste and environmental degradation. To address this challenge, novel materials with specified application goals, such as engineered plastic, have been developed and are intended for recycling and reuse. Despite the reuse and recycling, when plastic gets disposed into the environment, the degradation properties of plastics render a direct disposal hazard, posing a significant environmental threat. To mitigate these issues, the concept of replacing specific monomers of engineered synthetic plastics with bio-alternatives or blending them with other polymers to enhance sustainability and environmental compatibility has emerged. In this study, Acrylonitrile Butadiene Styrene (ABS) plastic is the focal material, and three distinct investigations were conducted. First, replacing ABS plastic's butadiene monomer with natural rubber was explored for its properties and environmental impact. Second, ABS plastic was blended with virgin, recycled, and bio-alternatives of PET (polyethylene terephthalate) and PVC (polyvinyl chloride) polymers. Lastly, recycled ABS blended with recycled PET and PVC was analyzed for mechanical properties. Comparative assessments of these blends were made based on mechanical properties, carbon emissions, and cost-effectiveness. The study determined that the r-ABS/r-PVC (recycled) blend exhibited the most favorable characteristics for practical application.

Fused Filament Fabrication of Polyethylene/Graphene Composites for In-Space Manufacturing.

Graphene-based composite materials are highly sought after for space applications due to their ability to encompass various properties, such as electrical conductivity, thermal resistance, and radiation shielding. This versatility allows for the creation of multifunctional components that can serve various purposes in space. Three-dimensional (3D) printing of composite materials in space offers a versatile and efficient means of manufacturing components, tools, and structures that are tailored to the unique challenges and requirements of space missions. In this work, we aim to develop 3D-printed composites made of medium-density polyethylene (MDPE) matrix and exfoliated graphene nanoplatelets (xGnP) as filler, using fused filament fabrication (FFF). Our research focuses on the challenges associated with the FFF process for fabricating MDPE/xGnP materials, particularly by optimizing filament extrusion and assessing the resulting material properties and space environmental compatibility. Firstly, we optimize the extrusion process, and use the MDPE/xGnP filaments to fabricate 3D-printed samples after defining the FFF parameters. We employ differential scanning calorimetry (DSC) to assess the melting properties and crystallization degree of the extruded filaments and 3D-printed samples, providing insights into the relationship between these properties and the characteristics of the initial powders. Electrical and tensile tests are carried out to evaluate the material properties after successfully mitigating challenges, such as warping and inadequate adhesion, to build plates during the printing process. Finally, we subject the 3D-printed composites to outgassing tests under exposure to the AM0 solar spectrum to evaluate their space environmental suitability. The results of this work demonstrate the capability of the FFF-based process to efficiently manufacture components made of MDPE/xGnP composites, providing optimized parameters for their potential in-space fabrication.

A comprehensive review on the use of Ti3C2Tx MXene in membrane-based water treatment

Population growth, industrial activities, and the energy demands of water production intensify the global challenge of accessing clean water. Membrane-based water treatment processes have emerged as crucial solutions to address this crisis, these include microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), forward osmosis (FO), reverse osmosis (RO), and membrane distillation (MD). This review summarizes the properties and use of Ti3C2Tx MXene, a material with notable chemical stability, specific surface area, hydrophilicity, thermal conductivity, and environmental compatibility. Ti3C2Tx fills in the class of two-dimensional materials, it is promising in various membrane processes by offering enhancement in hydrophilicity, permeability, and selectivity. In UF, Ti3C2Tx-based membranes have superior antifouling properties and high rejection rates of contaminants. Meanwhile, in NF, MXene nanosheets elevate the rejection of organics, dyes, and salts, and present valuable nanocomposite membranes. In desalination, incorporating Ti3C2Tx in RO membranes is found to increase water permeability while maintaining high salt rejection in desalination. Also, MXene-modified FO membranes had lower fouling and improved water flux compared with plain membranes, presenting a promising avenue for water purification. Additionally, Ti3C2Tx enhanced water vapor transport and resistance against wetting, which is favorable in MD.This review underscores the transformative potential of Ti3C2Tx MXene in revolutionizing membrane-based water treatment processes, providing innovative solutions to meet the escalating global demand for clean water. Future research directions should optimize MXene-based membrane designs and scale up their production for practical applications in water treatment, thereby contributing to a more sustainable water future.

Well-Defined Supported ZnOx Species: Synthesis, Structure, and Catalytic Performance in Nonoxidative Dehydrogenation of C3-C4 Alkanes.

ConspectusZinc oxide (ZnO) is a multipurpose material and finds its applications in various fields such as rubber manufacturing, medicine, food additives, electronics, etc. It has also been intensively studied in photocatalysis due to its wide band gap and environmental compatibility. Recently, heterogeneous catalysts with supported ZnOx species have attracted more and more attention for the dehydrogenation of propane (PDH) and isobutane (iBDH) present in shale/natural gas. The olefins formed in these reactions are key building blocks of the chemical industry. These reactions are also of academic importance for understanding the fundamentals of the selective activation of C-H bonds. Differently structured ZnOx species supported on zeolites, SiO2, and Al2O3 have been reported to be active for nonoxidative dehydrogenation reactions. However, the structure-activity-selectivity relationships for these catalysts remain elusive. The main difficulty stems from the preparation of catalysts containing only one kind of well-defined ZnOx species.In this Account, we describe the studies on PDH and iBDH over differently structured ZnOx species and highlight our approaches to develop catalysts with controllable ZnOx speciation relevant to their performance. Several methods, including (i) the in situ reaction of gas-phase metallic Zn atoms with OH groups on the surface of supports, (ii) one-pot hydrothermal synthesis, and (iii) impregnation/anchoring methods, have been developed/used for the tailored preparation of supported ZnOx species. The first method allows precise control of the molecular structure of ZnOx through the nature of the defective OH groups on the supports. Using this method, a series of ZnOx species ranging from isolated, binuclear to nanosized ZnOx have been successfully generated on different SiO2-based or ZrO2-based supports as demonstrated by complementary ex/in situ characterization techniques. Based on kinetic studies and detailed characterization results, the intrinsic activity (Zn-related turnover frequency) of ZnOx was found to depend on its speciation. It increases with an increasing number of Zn atoms in a ZnmOn cluster from 1 to a few atoms (less than 10) and then decreases strongly for ZnOx nanoparticles. The latter promote the formation of undesired C1-C2 hydrocarbons and coke, resulting in lower propene selectivity in comparison with the catalysts containing only ZnOx species ranging from isolated to subnanometer ZnmOn clusters. In addition, the strategy for improving the thermal stability of ZnOx species and the consequences of mass-transport limitations for DH reactions were also elucidated. The results obtained allowed us to establish the fundamentals for the targeted preparation of well-structured ZnOx species and the relationships between their structures and the DH performance. This knowledge may inspire further studies in the field of C-H bond activation and other reactions, in which ZnOx species act as catalytically active sites or promoters, such as the dehydroaromatization of light alkanes and the hydrogenation of CO2 to methanol.

Biosynthesis of Strontium Nanoparticles Using Mimosa pudica and its Antioxidant Effect

ABSTRACT A new area of nanotechnology, “green synthesis” studies nanomaterials utilizing natural biomaterials like plants, flowers, and microbesGreen nanoparticle synthesis offers various benefits, such as cost efficiency, pollution reduction, and environmental compatibility. Among nanoparticles, metallic variants have garnered the greatest attention due to their unique physical and chemical attributes. Strontium (Sr), known for promoting growth, aiding bone regeneration, and stimulating calcium signaling, holds significance in the medical domain. Consequently, Sr-based nanoparticles have gained interest in medical and dental applications due to their resemblance to calcium properties. Researchers worldwide are drawn to Mimosa pudica because of its pharmacological properties, including its ability to treat wounds, and its anti-diabetic, anti-toxin, anti-hepatotoxin, and antioxidant effects. Mimosa pudica mediated strontium nanoparticles’ antioxidant activity was tested against FRAP assay, H2O2 assay, and DPPH assay with ascorbic acid as standard, where in all three assays, increasing concentration of Mimosa pudica mediated strontium nanoparticles exhibited increasing antioxidant activity which was similar to the ascorbic acid. Hence, this can be used as a novel antioxidant agent in the near future.

Surface modification of poly (ethylene terephthalate) using imidazolium-based ionic liquids

Ionic liquids (ILs), with their unique characteristics, are widely known as new alternatives for solvents and catalysts used in various chemical reactions. Due to their extensive range of applications and environmental compatibility, they are suitable options for treating fibrous substrates. In this regard, this paper focuses on investigating the possibility of poly (ethylene terephthalate) surface modification via imidazolium-based ILs. Surface modification was carried out under different process conditions by varying the temperature and the catalyst. The possibility of treating samples in the IL solution for the second time was also examined. Moreover, the effect of the modification on the dyeing of polyester with disperse dye without carrier at 100 °C was studied. The samples’ wettability properties were investigated through several test methods by measuring vertical wicking height, wetting time, drop contact angle, surface resistivity and absorption of methylene blue dye. The chemical and physical changes of the modified samples were also evaluated via scanning electron microscopy images, Fourier-transform infrared spectroscopy (FTIR) spectra and mechanical tests. Results demonstrate that treatment with [BMIM]Cl and [BMIM]Br induces morphological changes on the fibre surface, creating grooves and voids. FTIR analysis and Methylene blue staining test confirm the formation of hydroxyl and carboxyl groups, enhancing the fabric's hydrophilicity and dyeability. Wettability tests reveal that increased water absorption leads to reduced electrical resistivity. Mechanical tests indicate a slight reduction in tensile strength attributed to surface roughness.

Three-Fold Coordination of Copper in Sulfides: A Blockade for Hole Carrier Delocalization but a Driving Force for Ultralow Thermal Conductivity.

Copper-rich sulfides are very promising for energy conversion applications due to their environmental compatibility, cost effectiveness, and earth abundance. Based on a comparative analysis of the structural and transport properties of Cu3BiS3 with those of tetrahedrite (Cu12Sb4S13) and other Cu-rich sulfides, we highlight the role of the cationic coordination types and networks on the electrical and thermal properties. By precession-assisted 3D electron diffraction analysis, we find very high anisotropic thermal vibration of copper attributed to its 3-fold coordination, with an anisotropic atomic displacement parameter up to 0.09 Å2. Density functional theory calculations reveal that these Cu atoms are weakly bonded and give rise to low-energy Einstein-like vibrational modes that strongly scatter heat-carrying acoustic phonons, leading to ultralow thermal conductivity. Importantly, we demonstrate that the 3-fold coordination of copper in Cu3BiS3 and in other copper-rich sulfides constituted of interconnected CuS3 networks causes a hole blockade. This phenomenon hinders the possibility of optimizing the carrier concentration and electronic properties through mixed valency Cu+/Cu2+, differently from tetrahedrite and most other copper-rich chalcogenides, where the main interconnected Cu-S network is built of CuS4 tetrahedra. The comparison with various copper-rich sulfides demonstrates that seeking for frameworks characterized by the coexistence of tetrahedral and 3-fold coordinated copper is very attractive for the discovery of efficient thermoelectric copper-rich sulfides. Considering that lattice vibrations and carrier concentration are key factors for engineering transport phenomena (electronic, phonon, ionic, etc.) in copper-rich chalcogenides for various types of applications, our findings improve the guidelines for the design of materials enabling sustainable energy solutions with wide-ranging applications.

Biosurfactant production by a crude oil‐utilizing bacterium towards petroleum hydrocarbon biodegradation applications

AbstractBiosurfactants produced by microorganisms are green amphiphilic biomolecules. They have numerous advantages compared to chemical surfactants including a lower toxicity, better environmental compatibility and effective and stable properties under extreme conditions such as a wide range of temperature, pH and salinity. A highly bio‐surfactant‐producing strain of Bacillus, VTVK15 was selected among the Bacillus isolates from marine environment and oil contaminated sites in Ba Ria‐Vung Tau. Sequence analysis of 16S rDNA showed that the VTVK15 strain was 99% similar with 16s rDNA sequence of Bacillus megaterium. The suitable conditions for the bio‐surfactant production by the strain VTVK15 were 37 °C, pH 7; 2% w/v and 0.4% w/v for temperature, initial solution pH, concentration of carbon substrate (crude oil), and concentration of nitrogen substrate ((NH4)2SO4), respectively. The emulsification index (E24) increased from 51.8% to 67.7% with suitable conditions. The petroleum hydrocarbon degradation (TPH) efficiency by the strain Bacillus megaterium VTVK15 in crude oil estimated using TPH analysis was 72% after 14 days. These results revealed that the strain VTVK15 exhibited a tremendous potential for bioremediation of petroleum hydrocarbon contaminants.