Search Results (207)

Heavy metal pollution has become a global environmental problem. Achieving efficient, stable, and sustainable immobilization of heavy metals by phosphorus (P)-modified biochar remains challenging because of the potential risk of P release. In this study, chitosan-embedded P-modified biochar (CPBC) was produced for the remediation of Pb(II), Cd(II), and Cr(VI). The specific surface area of CPBC was 5.5 times higher than that of the pristine biochar (BC), and the surface was enriched with functional groups such as -OH and -NH₃. P-modification facilitated the precipitation of the heavy metals, and chitosan blocked the precipitates inside the biochar. The nature of BC safeguarded the ability to transfer electrons and reduce Cr(VI) to Cr(III), which was further enhanced by the chitosan. Hence, the maximum sorption capacities of CPBC for Pb(II), Cd(II), and Cr(VI) were 29.23%, 129.13%, and 122.12% greater than those of BC. The sequential extraction confirmed that the immobilized Pb(II), Cd(II), and Cr(VI) on CPBC were highly stable, with the sum of acid-soluble and nonbioavailable fractions accounting for 89.14%, 83.73%, and 93.53%, respectively. In addition, chitosan effectively suppressed P release from the P-modified biochar, thereby improving its environmental safety while maintaining excellent heavy metal immobilization performance. The present study demonstrates that CPBC is an effective, environmentally friendly, and universal sorbent to remediate heavy metal pollution in water. Full article

Ammonia-responsive gelatin-based composite films containing cobalt metal–organic frameworks (Co–MOFs) synthesized using gallic acid as an organic ligand were developed and evaluated as intelligent packaging materials. Co–MOFs were incorporated into gelatin films at concentrations of 2.5, 5.0, 7.5, and 10.0% (w/w, based on gelatin). The effects of Co–MOF incorporation on the physicochemical, structural, thermal, mechanical, and sensing properties of gelatin films were systematically investigated. Increasing Co–MOF content reduced film moisture content (from 14.47 to 13.25–13.58%) and swelling capacity (from 599.37 to 484.88–547.30%), while increasing solubility (from 39.09 to 48.88%), water vapor permeability (WVP; from 1.652 to 2.054 g·mm/m²·h·kPa), and moisture sorption behavior. Sorption isotherm analyses based on the Guggenheim–Anderson–de Boer (GAB) and Brunauer–Emmett–Teller (BET) models confirmed enhanced water adsorption capacity and increased specific surface area in the films (from 356.13 to 455.74 m²/g). Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analyses demonstrated successful incorporation of Co–MOFs into the gelatin matrix, revealing good dispersion at low and moderate concentrations and partial aggregation at higher loadings. The incorporation of Co–MOFs improved the thermal stability of the films, while only a moderate reduction in mechanical strength was observed with increasing filler content. The composite films exhibited rapid and concentration-dependent colorimetric responses toward ammonia vapor. After 120 min of exposure, the color difference (ΔE) increased from less than 1 in the control film to approximately 12, 15, 24, and 27 for G/Co–MOF2.5, G/Co–MOF5, G/Co–MOF7.5, and G/Co–MOF10 films, respectively. Films containing higher amounts of Co–MOF showed faster response kinetics and greater color differences, enabling clear visual detection of ammonia. These findings demonstrate that gelatin/Co–MOF composite films based on gallic acid-derived metal–organic frameworks are promising intelligent packaging materials for monitoring food freshness and spoilage through ammonia detection. Full article

Hydrophobic organic compounds (HOCs) in water–soil systems pose persistent risks to pore water quality and groundwater safety because of their low aqueous solubility and strong soil sorption affinity. Electrokinetic remediation has emerged as a promising technology for controlling HOCs in contaminated water–soil systems, as it can regulate pore water movement, ionic migration, and contaminant transport under an applied electric field. However, the limited transfer of HOCs from soil into the aqueous phase restricts their electrokinetic removal efficiency, necessitating the use of surfactants to overcome these technical bottlenecks. This review elucidates the mechanistic basis of surfactant-enhanced electrokinetic remediation, with particular emphasis on micellar solubilization in pore water, contaminant desorption from soil matrices, and electrically driven transport across water–soil interfaces. Building on this mechanistic framework, the applications and performance of nonionic, anionic, cationic, biosurfactant, and mixed surfactants are summarized. Furthermore, the key factors governing surfactant efficacy are analyzed, including soil properties, contaminant characteristics, remediation objectives, operational parameters, environmental safety, and economic feasibility. By integrating mechanistic insights with environmental considerations, this review establishes a science-based framework for surfactant selection in electrokinetic remediation. This work provides a reference for enhancing contaminant transfer from soil matrices to the aqueous phase, reducing secondary risks to pore water and groundwater, and advancing the theoretical development and implementation of surfactant-enhanced electrokinetic remediation in environmental management. Full article

Starch-based bioplastics are renewable and biodegradable, but their wider use is constrained by moisture sorption, humidity-dependent aging, insufficient tensile performance, and weak water- and oxygen barrier stability. This review critically synthesizes the peer-reviewed literature from 2020 to 2026 on enzymatically engineered starch for film, packaging, and thermoplastic applications using an architecture–property framework that links enzyme specificity, chain-length distribution, crystallinity, processing route, and material response. Controlled α-1,4 hydrolysis mainly improves processability by lowering molecular weight, viscosity, and gelatinization resistance. However, excessive hydrolysis can increase water uptake, solubility, and loss of cohesive strength. Debranching by pullulanase or isoamylase increases amylose-like linear chains and can promote B-type crystallinity or V-type starch–lipid complexes, with reported gains in tensile strength, contact angle, and water vapor barrier when the chain lengths and recrystallization conditions are controlled. Branching enzymes and transglycosylases increase branch density or redistribute glucan chains, suppressing retrogradation and improving flexibility, water retention, and aging resistance, but often with trade-offs in strength, crystallinity, and barrier performance. Lipase- and laccase-catalyzed functionalization expands starch functionality by increasing hydrophobicity, compatibility with hydrophobic phases, antioxidant activity, and active-packaging potential. The evidence indicates that enzymatic modification should not be generalized as uniformly improving starch bioplastics; performance gains are conditional on the starch source, amylose content, enzyme dosage, reaction severity, plasticizer composition, processing method, film conditioning, and storage humidity. Industrial implementation remains limited by enzyme cost and reuse, high-solids mass transfer, reaction time, enzyme stability under heat and shear, and reproducibility across botanical sources. Overall, enzymatic molecular editing is most promising when mechanistic architecture control is coupled with standardized structure–property reporting and scalable processing, such as immobilized-enzyme reactors, high-solids systems, and reactive extrusion. Full article

The study aimed to develop and preliminarily characterize experimental resin-based dental composites (RBCs). In addition to the composites, didodecyldimethylammonium bromide (DDAB) was used as a biocide in various concentrations (0–3 wt%). Hardness (HV), flexural strength (FS), and modulus of elasticity, as well as diametral tensile strength (DTS) of composites, were examined. Additionally, shrinkage stress, surface free energy (SFE), water sorption (Wsp), and solubility (Wsl) were determined. Cytometric analysis, including biocidal surface testing and susceptibility to colonization by Streptococcus mutans, Escherichia coli, and Candida albicans, assessed antibacterial activity. The HV of RBCs varied from 27.2 ± 1.5 to 31.5 ± 1.8 depending on DDAB amount, FS—67.0 ± 16.1 MPa for control composite and 79.2 ± 14.5 MPa for modified composite. All DTS values exceed 24 MPa. Shrinkage stress is highest for the composite with 0.25 wt% DDAB—18.5 ± 1.9 MPa—and lowest for the composite with 1 wt% DDAB—15.0 ± 2.5 MPa. Wsp is lowest in the control group (37.19 ± 1.69 µg/mm³) and highest for 1 wt% modifier (42.11 ± 2.75 µg/mm³). Wsl was at its lowest in control group (1.98 ± 1.58 µg/mm³), and highest for modification with 1 wt% (3.91 ± 1.74 µg/mm³). For RBCs modified with 3 wt% DDAB after 60 min, an increase in dead cells is observed: 51% for Escherichia coli, 71% for Streptococcus mutans, and 24% for Candida albicans. Preliminary results show that DDAB effectively reduced the presence of the tested pathogens and contraction stress; however, at certain concentrations it negatively influences hardness and water sorption of composites. The presented findings highlight both the potential and the limitations of DDAB-modified RBCs and underline the need for further studies, including cytotoxicity and genotoxicity assessments, release analyses and evaluation of composites’ ageing behavior. Full article

The production of inexpensive, effective sorbents from natural materials for the purification of water bodies and/or soils is a pressing problem. Therefore, the purpose of this manuscript is to summarize current approaches to the use of brown coal (lignite) and its processing products (humic acids, HAs) as sorbents for the purification of aqueous and soil environments from heavy metal ions and other pollutants. Modification of lignite (chemical, biological, physicochemical) or the creation of lignite–mineral composites significantly increases its sorption capacity and stability: after modification, the sorption capacity can reach more than 85 mg of heavy metals per g of sorbent, which is only 3 times lower than that of specialized, expensive sorbents. Also, good results are achieved in the case of sorption of water-soluble organic drugs, dyes, etc. Humic acids obtained from brown coal have better selectivity and efficiency than the original lignite, and slightly worse than the modified one, in terms of removing cadmium, lead, copper, and other toxic elements; and also, can complex with organic xenobiotics. Current research trends indicate growing interest in multifunctional composite sorbents, environmentally friendly extraction technologies, and the development of materials with enhanced selectivity and regeneration ability. Future studies should focus on improving the understanding of sorption mechanisms, optimizing modification strategies, scaling up lignite-based technologies for practical environmental applications, and developing waste-free technologies to produce sorbents from lignite. Full article

Layered double hydroxides (LDHs) are promising anion sorbents, but conventional Mg–Fe LDH synthesis requires prolonged aging. The effects of ultrasound application stage on Mg–Fe LDH microstructure and chromate uptake remain insufficiently clarified. This study compared ultrasonic treatment during and after coprecipitation and related XRD-derived microstructural descriptors to Cr(VI) sorption. Mg–Fe LDHs were synthesized using 28 or 40 kHz ultrasound during or after coprecipitation and 1.7 MHz ultrasound after coprecipitation; 24 h thermal aging was used as a reference. The products were characterized by ICP-MS, FTIR, TGA/DSC, SEM, and XRD and tested for chromate adsorption, kinetics, recyclability, multicomponent-solution performance, and soil Cr(VI) immobilization. Fifteen minutes of ultrasonication yielded Mg/Fe ≈ 2 LDHs and shortened synthesis compared with 24 h aging. Ultrasound during coprecipitation at 28 kHz gave the best sorbent, increasing experimental adsorption capacity to 80.35 mg/g versus 53.70 mg/g for the reference LDH. Sorption followed pseudo-second-order kinetics and was best described by the Freundlich model. In a multicomponent solution, this sample removed 68% Cr(VI) at 1.0 g/L and reduced water-soluble Cr(VI) in soil from 14.31 to 0.26 mg. Ultrasound application during coprecipitation improves Mg–Fe LDH structure-related characteristics and chromate sorption. Full article

Three-dimensional (3D) printing is increasingly used for the fabrication of definitive crowns; however, whether specific post-curing hardware is mandatory for clinical success remains a practical concern. This study provided a practical comparison evaluating the effect of two post-curing units on the biaxial flexural strength (BFS), Weibull modulus (m), Martens hardness (HM), indentation modulus (EIT), water sorption (WSP), and water solubility (WSL) of 3D-printed resins for permanent crowns, compared with a conventional resin composite. A total of 200 specimens were fabricated from two 3D-printed resins (Permanent Crown™ and CrownTec™) and a conventional resin composite (Filtek Universal Restorative™) used as a control. The 3D-printed specimens were post-cured using either a Formcure or an Otoflash G171 unit. WSP and WSL were measured after 90 days of water ageing, while BFS, HM, and EIT were evaluated after 24 h of storage using standardised methods. All materials exhibited WSP and WSL values within ISO limits, with the control group showing significantly higher values and superior mechanical properties. Among the 3D-printed resins, post-curing significantly affected only HM and EIT for Permanent Crown™ resin, with no significant differences in BFS. Overall, the tested 3D-printed resins demonstrated high processing stability across different curing protocols, suggesting that clinical performance remains consistent regardless of the post-curing unit used. Full article

Dental restorative resins available today still have limitations that may affect their durability. This study explores reinforcing a universal microhybrid dental composite resin with organomodified nanoclay at low filler loadings (0, 0.5, 1, 3, and 5 wt%). The morphology, structural features, and light transmittance of the composites were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), attenuated total reflection–Fourier transform infrared (ATR–FTIR), and UV–Vis spectroscopy. The degree of conversion and polymerization shrinkage were measured with ATR–FTIR and a linear variable displacement transducer (LVDT). Water sorption and solubility parameters and flexural properties were assessed gravimetrically and with a dynamometer, respectively. The composites mainly showed exfoliated structures and an improved degree of conversion. Polymerization shrinkage and solubility were lower than those of unmodified dental resin. The highest degree of conversion was observed in composites with 0.5–1 wt% nanoclay. The incorporation of 1 wt% nanoclay resulted in the lowest shrinkage and sorption, along with the highest flexural modulus and strength. Overall, the results suggest that low nanoclay concentrations can improve the physicochemical and mechanical properties of dental composites, highlighting their potential to develop advanced restorative materials that can address current clinical challenges. Full article

Sunset Yellow is a water-soluble synthetic dye resistant to degradation and stable under various conditions, posing an environmental challenge. In the present study pure chitosan hydrogel (PCH) films were synthesized, followed by the assessment of sorption capacity and recyclability compared to chitosan-based films doped with niobium oxide (CHN) or activated carbon (CHC). The aim was to promote the application of sorption methods for Sunset Yellow dye using these films as a treatment option for the pollutant, with the analysis of the effectiveness of the method and its behavior using adsorption kinetic models and thermodynamic analysis. Equilibrium was reached at 240 min for all films tested, with the adsorbed amounts ranging from 18.58 to 18.79 mg g⁻¹ at 30 °C, when the highest kinetic rate constants were observed. The pseudo-first-order kinetic model best described the experimental data, with the lowest Bayesian information criterion, Akaike information criterion, and mean absolute error values. Thermodynamic analysis indicated a spontaneous, exothermic process, with interactions ranging from electrostatic interactions in CHC and PCH to physisorption in CHN. Recycling tests showed 80% efficiency after the third cycle for all three films. These findings highlight the potential of chitosan-based films as an efficient option for removing Sunset Yellow dye from water, thus improving water quality and enhancing wastewater treatment. Full article

Objective: To determine the most suitable core build-up materials based on their mechanical and physical properties, different resin based materials were evaluated for flexural strength (FS), flexural modulus (E), modulus of resilience (R), water sorption (WS), and solubility (SO). Materials and Methods: Three dual-cure resins (CosmeCore DC Automix, CCC; Clearfil DC Core Plus, CCP; MultiCore Flow, CMC) and two bulk fill composites (Filtek One Bulk Fill Restorative, BFO; Filtek Bulk Fill Flowable, BFF) were tested, with Filtek Supreme Ultra (FSU) as the control. All tests followed ISO 4049. Beam specimens (25 × 2 × 2 mm, n = 12) were used to determine FS and E after 24 h storage in 37 °C deionized water, using a three-point bending test. Disc specimens (15 × 1 mm, n = 5) were used for WS and SO by measuring mass changes before and after water storage. Data were analysed using one way ANOVA and Tukey post hoc tests (p < 0.05). Results: CCC exhibited the highest FS and lowest WS. BFF showed the lowest E, while BFO exhibited the highest R. FSU demonstrated the lowest FS and R, along with the highest WS. No significant differences in SO were observed among groups. Conclusions: The evaluated materials showed considerable variation in mechanical and physical properties. CCC and BFO demonstrated the most favourable performance, suggesting they are the most suitable candidates for core build up procedures among the materials tested. Full article

Glass ionomer cements (GICs) are considered functionally biomimetic as they participate in ion-exchange processes that partially resemble the behavior of natural enamel and dentin, chemically bond to dental hard tissues, and release fluoride. While GICs are designed to interact with aqueous oral environments, their exposure to dietary beverages may affect their esthetic stability and water-related behavior within the oral environment. For biomimetic restorative materials to perform successfully in the oral environment, they must maintain not only bioactive properties but also esthetic stability and resistance to water-related degradation during exposure to dietary beverages. This study evaluated beverage-induced color changes, water sorption, and water solubility of six GICs following their immersion in coffee, tea, berry juice, cola, and distilled water (n = 5 per material per solution). Color measurements were recorded at baseline and after 2, 4, 6, and 8 weeks using a spectrophotometer, and color change (ΔE) values were calculated using the CIE L*a*b* system. Specimen mass was measured at baseline, after 8 weeks of immersion and then after 4 weeks of desiccation. Data were analyzed using repeated-measures Analysis of Variance (ANOVA) and Fisher’s least significant difference post hoc tests (α = 0.05). The results showed time, material, and solution significantly affected ΔE (p < 0.001). Tea produced the greatest discoloration overall, followed by coffee. ChemFil exhibited the greatest staining susceptibility, while Fuji II showed the lowest staining susceptibility. Water sorption and solubility were material- and solution-dependent. Clinically relevant discoloration of GICs was found when immersed in common beverages over time, with tea showing the strongest staining effect. These findings indicate that although GICs exhibit biomimetic characteristics through their interaction with tooth structures and aqueous environments, their long-term esthetic stability and resistance to environmental challenges should also be considered when selecting restorative materials for clinically visible areas. Full article

Self-curing poly(methyl methacrylate) (PMMA) remains widely used for provisional restorations and denture bases; however, its limited mechanical strength and susceptibility to water-related degradation restrict long-term performance. This study investigated the concentration-dependent reinforcement of self-curing PMMA with polyetheretherketone (PEEK) particles and evaluated mechanical properties and physicochemical stability. PMMA specimens containing different PEEK concentrations were fabricated and tested for flexural strength, compressive strength, surface hardness, water sorption, and water solubility according to standardized protocols. Mechanical performance demonstrated a concentration-dependent enhancement, with moderate PEEK incorporation significantly improving strength parameters compared to the control group. Excessive filler loading, however, did not yield proportional improvements. Water sorption and solubility values remained within clinically acceptable and ISO-recommended limits. These findings suggest that controlled PEEK reinforcement provides a feasible approach to enhancing the mechanical durability of self-curing PMMA without compromising physicochemical stability. The study offers a practical material modification strategy for improving interim prosthetic materials in clinical dentistry. Full article

This study investigated how fabrication method (milling versus 3D printing) affects the water sorption and solubility of PMMA dental materials, and how surface characteristics affect hydrolytic stability. Fifty-six PMMA samples were divided into three groups fabricated from CAD/CAM milled discs (Group A: I–III) and four groups from 3D-printed resin (Group B: IV–VII), each subjected to distinct postprocessing protocols. Water sorption (wsp) and solubility (wsl) were measured after immersion in distilled water at 37 °C for 24, 48, and 72 h, and 7 and 14 days. Surface topography and nanoroughness were assessed using atomic force microscopy (AFM). Statistical descriptive analyses were followed by correlation analyses. Milled PMMA demonstrated significantly lower water sorption and negative solubility (mass loss), indicating material dissolution. In contrast, 3D-printed PMMA showed higher water sorption and positive solubility (mass gain), reflecting water incorporation and polymer swelling. The kinetic profiles differed: milled PMMA displayed a monophasic absorption curve, while 3D-printed PMMA exhibited a biphasic pattern with accelerated water uptake after 72 h. AFM analysis revealed that 3D-printed surfaces had significantly greater nanoroughness than milled surfaces. Strong positive correlations were observed between surface roughness parameters (Sa, Sy) and water sorption capacity. The fabrication method was found to influence the hydrolytic stability of PMMA dental materials. Milled PMMA demonstrated superior stability, with lower water uptake, smoother surfaces, and lower leaching solubility. In contrast, 3D-printed PMMA exhibited increased surface roughness and water sorption, attributed to its layered microstructure and nanoporosity. Surface topography emerged as a strong predictor of wsl, related to hydrolytic degradation. For clinical applications, milled PMMA is recommended for long-term use requiring durability, whereas 3D-printed PMMA may be appropriate for short-term applications with optimised postprocessing. Full article

Background/Objectives: Bulk-fill (BF) resin-based composites (RBCs) have become increasingly popular due to their efficient placement. However, there is a lack of comprehensive performance comparisons among commercially available BF RBCs. In standardized curing conditions, this study aimed to compare the mechanical performance, water sorption and solubility, surface roughness, and color stability of commercially available BF RBCs with different consistencies (flowable and packable). Methods: Ten BF RBCs, along with a conventional RBC (control), were evaluated. Flexural strength and elastic modulus were measured using a three-point bending test. Water sorption and solubility were assessed after 28-day water storage. Color (ΔE₀₀) and surface roughness (ΔRa) changes were measured after 28-day immersion in water, Pepsi, or coffee. One-way ANOVA and Tukey’s tests analyzed the data. Results: 3M Flow, Shofu Bulk, and Ivoclar Flow revealed lower strength (p < 0.001) compared to 3M Bulk (132.17 ± 12.54 MPa) and the control (124.56 ± 15.60 MPa). Shofu Bulk (24.68 ± 12.55 µg/mm³) and Ivoclar Flow (27.11 ± 6.27 µg/mm³) were the least affected by water sorption. While Shofu Bulk (13.98 ± 11.39 µg/mm³), Ivoclar Flow (20.28 ± 6.64 µg/mm³), and SDR (20.84 ± 9.74 µg/mm³) exhibited the lowest solubility (p < 0.01). After water and Pepsi immersion, FGM Bulk showed a significant color change compared to 3M Bulk and Ivoclar Bulk (p < 0.05). Following coffee immersion, Shofu Bulk (17.38 ± 1.82) revealed significant color changes (p < 0.001). Increased surface roughness was observed in 3M Bulk and Ivoclar Bulk after water immersion, Shofu Bulk after Pepsi immersion, and FGM Bulk after coffee immersion. Conclusions: BF RBCs exhibit notable variability in their intrinsic properties. 3M Bulk and Control showed the highest strength, while Shofu Bulk had significant color changes. Full article