Search Results (87)

This study examines the effect of temperature during pyrolysis on the capacity of cedar wood-derived biochar to be employed as a sustainable electrode material for supercapacitors. Cedar wood-derived biochars were produced at different temperatures of 800 °C, 900 °C, 1000 °C and 1100 °C and fully characterized in terms of their structural, physicochemical and electrochemical properties, including specific surface area, hydrophobicity, electrical conductivity, and surface functional groups. The results indicated that the cedar wood biochar obtained through pyrolysis at 900 °C (BC900) provided optimal electrical conductivity, hydrophobicity, and porosity characteristics relative to the other cedar wood biochars produced by pyrolysis at 800 °C to 1100 °C. Specifically, when compared to commercial activated carbon (AC), BC900 provided half the specific capacitance at a current density of 1 A g⁻¹ and indicated that there is more potential for improvement with further activation and doping. The influence of the binder (either polyvinylidene fluoride (PVDF) or chitosan) in combination with conductive carbon black (CB) was also examined. Electrodes fabricated with PVDF binder showed higher specific capacitance, while biochar electrodes made from CB and chitosan (BC900/CB/chitosan) showed better electrical conductivity, wettability, and good electrochemical stability with >95% capacity retention even after 10,000 cycles. Full article

High safety gel polymer electrolyte (GPE) is used in lithium metal solid state batteries, which has the advantages of high energy density, wide temperature range, high safety, and is considered as a subversive new generation battery technology. However, solid-state lithium batteries with multiple layers and large capacity currently have poor cycle life and a large gap between the actual output cycle capacity retention rate and the theoretical level. In this paper, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP)/polyacrylonitrile (PAN)—lithium perchlorate (LiClO₄)—lithium lanthanum zirconium tantalate (LLZTO) gel polymer electrolytes was prepared by UV curing process using a UV curing machine at a speed of 0.01 m/min for 10 s, with the temperature controlled at 30 °C and wavelength 365 nm. In order to study the performance and failure mechanism of multilayer solid state batteries, single and three layers of solid state batteries with ceramic/polymer composite gel electrolyte were assembled. The results show that the rate and cycle performance of single-layer solid state battery with gel electrolyte are better than those of three-layer solid state battery. As the number of cycles increases, the interface impedance of both single-layer and three-layer electrolyte membrane solid-state batteries shows an increasing trend. Specifically, the three-layer battery impedance increased from 17 Ω to 42 Ω after 100 cycles, while the single-layer battery showed a smaller increase, from 2.2 Ω to 4.8 Ω, indicating better interfacial stability. After 100 cycles, the interface impedance of multi-layer solid-state batteries increases by 9.61 times that of single-layer batteries. After 100 cycles, the corresponding capacity retention rates were 48.9% and 15.6%, respectively. This work provides a new strategy for large capacity solid state batteries with gel electrolyte design. Full article

Elevated fluoride levels in drinking water pose a significant health risk for communities relying on groundwater in the Ethiopian Central Rift Valley. This study aims at characterizing real groundwater samples from the Ethiopian Central Rift Valley and evaluating the performance of an integrated membrane process based on reverse osmosis (RO) and membrane crystallization (MCr) for fluoride removal and its recovery as mixed fluoride salts. Groundwater analysis revealed fluoride concentrations of 20.8 mgL⁻¹ at the Meki-01 site and 22.7 mgL⁻¹ at the Meki-02 site, both exceeding the WHO guideline of 1.5 mgL⁻¹. In addition, total dissolved solids exceeded 1000 mgL⁻¹ at both sites, classifying the water as brackish. A commercial RO membrane demonstrated excellent fluoride and ion rejection, with fluoride removal rates exceeding 99%. The total dissolved solids (TDS) removal efficiency reached 89%. The mean water permeability of the membrane was 4.52 Lm⁻²h⁻¹bar⁻¹. The retentate produced in the RO unit reached a concentration of 70 mgL⁻¹, which was then treated using osmotic membrane distillation–crystallization (OMD-Cr) and/or vacuum membrane crystallization (VM-Cr). This process facilitated the recovery of mixed salts while achieving an almost zero-liquid discharge. The study confirms the successful removal of fluoride and its recovery as mixed salt, along with the recovery of water in an environmentally friendly and manageable way. Full article

Ultrafiltration is essential for wastewater treatment, but it faces challenges such as selectivity, control, and fouling reduction. Incorporating nanoparticles into membranes enhances retention, boosts permeability, and limits fouling, improving overall performance. This study explores the properties of PVDF/Ag-ZnO composite membranes, highlighting the influence of silver-doped zinc oxide nanoparticles on membrane structure, performance, and antimicrobial effect. The non-solvent-induced phase separation (NIPS) method successfully led to the preparation of composite membranes; this method used different doses of silver-doped zinc oxide (Ag-ZnO) nanoparticles with Poly(vinylidene fluoride) (PVDF). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and water contact angle measurements were used to validate the influence of nanoparticles on the composite membrane (PVDF/Ag-ZnO) structure. Conversely, morphology (porosity, surface rigorosity), hydrophilicity, and permeability were analyzed through contact angle, image analysis, and flux measurement. In addition, the membranes were tested for antimicrobial activity against E. coli. Membrane performance shows that the incorporation of 20% w/w Ag-ZnO resulted in improved water permeability, which was about 2.73 times higher than that of a pure PVDF membrane (192.2 L·m⁻²·h⁻¹·bar⁻¹). The membrane porosity showed a linear increase with the number of NPs. The resultant asymmetric membrane was altered to increase the number of pores on the top surface by 61% and the cross-sectional pore surface by 663%. Furthermore, a high antibacterial activity of Ag-ZnO 20% was shown. Full article

Solid-state electrolytes are widely expected to enhance the performance of lithium-ion batteries, providing higher energy density and improved safety. However, challenges still need to be solved in their practical application due to low ionic conductivity and high interfacial resistance at room temperature. In this study, we successfully developed a high-performance gel polymer electrolyte (GPEs) by blending poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) and polyacrylonitrile (PAN) through UV curing, cross-linking with ethoxylated trimethylolpropane triacrylate (ETPTA), and incorporating Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO). At room temperature, the ionic conductivity of the GPEs was 2.8 × 10⁻⁴ S/cm, with a lithium-ion transference number of 0.6. Moreover, during lithium plating/stripping tests, the assembled Li/PPEL/Li symmetric cell exhibited stable cycling for up to 600 h at a current density of 0.1 mA/cm². Notably, the GPEs enabled the LiFePO₄/GPEs/Li battery to achieve excellent performance, delivering high discharge capacities at room temperature (164.3 mAh g⁻¹ at 0.1 C and 88.8 mAh g⁻¹ at 1 C), with a capacity retention of 89.4% after 200 cycles at 0.5 C. Therefore, solid-state batteries using this electrolyte exhibit excellent performance, including adequate capacity and cycling stability. Full article

This study examines the effects of natural organic matter (NOM) and dissolved solids on fluoride (F⁻) retention in polyelectrolyte multilayer-based hollow-fiber nanofiltration membranes (dNF40). Lab-scale filtration experiments were conducted under varying operating conditions (initial salt concentration, NOM concentration, permeate flux, crossflow velocity, and recovery rate). dNF40 membranes exhibited F⁻ retention above 70% ± 1.2 in the absence of NOM and competing ions. However, when filtering synthetic model water (SMW) designed to simulate groundwater contaminated with high total dissolved solids (TDSs) and NOM, F⁻ retention decreased to approximately 60% ± 0.7, which was generally attributed to ion competition. Furthermore, despite limited declines in normalized permeability, the addition of NOM to SMW notably deceased F⁻ retention in the steady state to~20% due to fouling effects. The facilitated transport of the divalent cations Ca²⁺ and Mg²⁺ could be observed, as they accumulated in the organic fouling layer. While SO₄²⁻ retention remained relatively stable, the retention of monovalent anions (NO₃⁻, Cl⁻, and F⁻) decreased substantially due to drag effects. Na⁺ retention improved slightly to maintain electroneutrality. Feed salinity was shown to significantly affect separation efficiency, with PEC layers undergoing swelling and certain structural changes as the ionic strength increased. During batch filtration experiments at varying recovery rates, the retention of monovalent anions further decreased, with F⁻ retention reducing to just ~10% at a 90% recovery rate. This study provides valuable insights into better understanding and optimizing the performance of PEC-based NF membranes across diverse water treatment scenarios. Full article

Copper foil has been widely adopted as the anode current collector in commercial lithium-ion batteries (LIBs) due to its exceptional electrical conductivity, mechanical flexibility, and low cost. However, the smooth surface of copper foil often leads to active material delamination during cycling, resulting in accelerated capacity degradation. To address this limitation, this study developed a novel composite current collector featuring a high specific surface area and rough porous architecture through a dip-coating method. The fabrication process employs copper mesh as a structural skeleton, integrated with carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) as functional fillers. Compared to conventional metallic copper foils, the composite current collector demonstrates superior interfacial wettability, enhanced adhesion strength, and reduced contact resistance. When paired with graphite as the active material, the graphite composite electrode exhibits outstanding cycling stability and rate capability. Specifically, the graphite composite electrode delivers a specific capacity of 297.9 mAh g⁻¹ with 94.3% capacity retention after 200 cycles at 0.5 C, significantly outperforming the graphite–copper foil counterpart (238.3 mAh g⁻¹, 81.2% retention). This work provides an innovative strategy for enhancing battery performance through the rational design of efficient and durable current collectors. Full article

Dental caries is a prevalent global health issue characterized by the progressive demineralization of dental tissues, which occurs when the balance between demineralization and remineralization processes is disrupted at the tooth level. Silver diamine fluoride (SDF) has gained recognition for its ability to arrest caries. However, its interaction with mineralized tissues remains incompletely understood. This study aimed to investigate the chemical interactions between SDF and mineralized bioceramics, using hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) as analogs for enamel and dentin. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were employed to identify functional groups and quantify elemental compositions at varying depths. FTIR analysis revealed structural modifications in HA and β-TCP. XPS demonstrated high retention of fluoride, with limited penetration into deeper layers, while silver exhibited deeper penetration. These findings suggest that SDF primarily acts on superficial layers, forming calcium fluoride and silver phosphate as key reaction products. These findings highlight the potential of SDF in managing deep carious lesions by demonstrating its ability to form a protective CaF₂ layer at the surface while allowing deeper penetration of silver ions into mineralized tissues. This dual mechanism may contribute to SDF’s clinical efficacy in arresting caries and preventing further demineralization. Full article

This study explores the preparation of lithium iron phosphate (LFP) electrodes for lithium-ion batteries (LIBs), focusing on electrode loadings, dispersion techniques, and drying methods. Using a three-roll mill for LFP slurry dispersion, good electrochemical properties were achieved with loadings of 5–8 mg·cm⁻² (0.8–1.2 mAh·cm⁻² areal capacity). Adding polyvinylidene fluoride (PVDF) during the final milling stage reduced performance due to premature solidification in-between rolls. Vacuum-free drying improved ionic conductivity, stability against lithium metal, and discharge capacity, whereas vacuum-dried samples exhibited higher initial resistance and lower capacity retention. These findings highlight critical parameters for enhancing LFP electrode performance, paving the way for high-performance, and sustainable energy-storage solutions. Full article

Car wash wastewater (CWW) is complex waste that may be effectively treated by the ultrafiltration (UF) process. However, one of the most important challenges in implementing this process on an industrial scale is the fouling phenomenon membrane aging. Indeed, these may lead to a reduction in UF performance possibly associated with a loss in integrity of the fouled/aged membrane. Therefore, the main aim of the current study was to provide a comprehensive investigation on the changes in the separation properties of aged FP100 ultrafiltration membranes made of polyvinylidene fluoride (PVDF) with respect to their application for long-term treatment of CWW. For this purpose, studies were conducted for new membranes and membranes previously used for over 5 years in a pilot plant. As a feed, solutions of dextran, solutions of model organism Escherichia coli and synthetic CWW were used. It has been found that PVDF membranes demonstrated poor stability when in frequent contact with chemicals periodically applied for membrane cleaning. Indeed, the aged membranes were characterised by the increased porosity. However, it is important to note that membranes aging had no significant impact on the permeate quality during the UF process of synthetic CWW. Indeed, the obtained permeate was characterised by the turbidity lower than 0.25 NTU. Likewise, with regard to the separation of E. coli, the aged PVDF membranes ensured the high process efficiency and over 99.99% bacterial retention. In the interest of the growing potential of PVDF membrane in CWW treatment, the results obtained in the current work complement the findings made in this field. Full article

This study examines the adsorption and desorption behaviors of phosphorus (P), arsenic (As), fluoride (F), and chromium (Cr) in aqueous solutions on green materials such as cork bark (CB) and pine bark (PB). These materials are characterized by active functional groups and net negative charges on their surfaces and porous structures. The evaluation considers variations in contaminant concentrations (0.01–10 mM) and pH (3.5–12). Cork bark exhibited higher adsorption capacity for As and F, while PB was more effective for P and Cr. Adsorption isotherms followed the Freundlich and Langmuir models, indicating surface heterogeneity and multilayer adsorption for most potentially toxic elements (PTEs). Desorption tests demonstrated low rates, with CB retaining up to 99% of F and 85% of As, and PB achieving up to 86% retention for Cr and 70% for P. The influence of pH was minimal for As, P, and F, but acidic conditions significantly enhanced Cr adsorption, showing similar behavior for both biopowders. These findings suggest that CB and PB biopowders are promising, environmentally friendly biosorbents for the removal of PTEs from aqueous solutions. Their effectiveness varies depending on the specific contaminant. This study highlights the potential of these natural materials for sustainable applications in water treatment and soil remediation. Full article

Aqueous zinc-ion batteries (AZIBs) have emerged as highly promising options for large-scale energy storage systems due to their cost-effectiveness, substantial energy capacity, and improved safety features. However, the Zn anode faces challenges such as self-corrosion and dendrite formation, which limit its practical use in AZIB applications. In this work, a simple blade-coating method was used to successfully coat poly (vinylidene fluoride–hexafluoro propylene) (PVDF-HFP) on the Zn anode. The coated Zn anode (P-Zn) displayed a stable cycling performance (700 h) at 1 mA cm⁻² current density in the symmetric cell. In addition, the full cell using MnO₂ as the cathode and P-Zn as the anode retained almost full capacity even after 1400 cycles at 2C, far outperforming the full cell using the unmodified Zn anode with only 50% capacity retention after 600 cycles. In situ optical observations of Zn deposition demonstrate that the special organic coating significantly enhances the uniform deposition of Zn²⁺, thus effectively mitigating corrosion and hydrogen evolution. Density Functional Theory (DFT) calculations show that the PVDF-HFP coating effectively narrows the adsorption energy gap between the P-Zn (002) and (101) planes, leading to the homogeneous deposition of Zn²⁺ with fewer Zn dendrites. A simple and feasible strategy for designing ultra-stable AZIBs by coating an organic protective layer on the Zn surface is provided by this work. Full article

Ultrafiltration membranes in the fields of water treatment and biomedicine should have high permeability as well as antibacterial and antifouling capabilities. In this study, based on the hydrophilicity of fullerol (C₆₀(OH)_n) and the bacteriostatic properties of silver (Ag), a fullerol–silver (C₆₀(OH)_n-Ag) complex was prepared as a multifunctional additive. A polyvinylidene fluoride (PVDF)-composited C₆₀(OH)_n-Ag ultrafiltration membrane (C₆₀(OH)_n-Ag/PVDF) was prepared by immersion precipitation phase transformation. Addition of the C₆₀(OH)_n-Ag complex improved the permeability and retention of the traditional PVDF membrane. Compared with the traditional PVDF membrane, the surface water contact angle of the modified PVDF and C₆₀(OH)_n-Ag ultrafiltration membrane was reduced from 75.05° to 34.50°, its pure water flux increased from 224.11 L·m⁻²·h⁻¹ to 804.05 L·m⁻²·h⁻¹, the retention rate on bovine serum protein was increased from 75.00% to 96.44% and the flux recovery rate increased from 64.91% to 79.08%. The C₆₀(OH)_n-Ag/PVDF ultrafiltration membrane had good inhibitory effects on Escherichia coli and Staphylococcus aureus, while the PVDF ultrafiltration membrane had no obvious inhibitory effects. Full article

Solid-state electrolytes are widely anticipated to revitalize lithium-ion batteries with high energy density and safety. However, low ionic conductivity and high interfacial resistance at room temperature pose challenges for practical applications. This study combines the rigid oxide electrolyte LLZTO with the flexible polymer electrolyte poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to achieve effective coupling of rigidity and flexibility. The semi-interpenetrating network structure endows the PEL composite solid electrolyte with excellent lithium-ion transport capabilities, resulting in an ionic conductivity of up to 5.1 × 10⁻⁴ S cm⁻¹ and lithium-ion transference number of 0.41. The assembled LiFePO₄/PEL/Li solid-state battery demonstrates an initial discharge capacity of 132 mAh g⁻¹ at a rate of 0.1 C. After 100 charge–discharge cycles, the capacity retention is 81%. This research provides a promising strategy for preparing composite solid electrolytes in solid-state lithium-ion batteries. Full article

In this work, we designed a novel polyvinylidene fluoride (PVDF)@DNA solid polymer electrolyte, wherein DNA, as a plasticizer-like additive, reduced the crystallinity of the solid polymer electrolyte and improved its ionic conductivity. At the same time, due to its Lewis acid effect, DNA promotes the dissociation of lithium salts when interacting with lithium salt anions and can also fix the anions, creating more free lithium ions in the electrolyte and thus improving its ionic conductivity. However, owing to hydrogen bonding between DNA and PVDF, excess DNA occupies the lone pairs of electrons of the fluorine atoms on the PVDF molecular chains, affecting the conduction of lithium ions and the conductivity of the solid electrolyte. Hence, in this study, we investigated the effects of adding different DNA amounts to solid polymer electrolytes. The results show that 1% DNA addition resulted in the best improvement in the electrochemical performance of the electrolyte, demonstrating a high ionic conductivity of 3.74 × 10⁻⁵ S/cm (25 °C). The initial capacity reached 120 mAh/g; moreover, after 500 cycles, the all-solid-state batteries exhibited a capacity retention of approximately 71%, showing an outstanding cycling performance. Full article