Search Results (4,280)

Agricultural waste management is a strategic priority for reducing greenhouse gas emissions and transitioning to a circular bioeconomy. The thermochemical conversion of residual biomass into biochar offers a dual solution: waste recovery and the production of high-value functional materials. This narrative review summarizes the relationships among the composition of agricultural biomass, the conversion process parameters, and the structural properties of biochar, highlighting advanced modification strategies: controlled pyrolysis, physical and chemical activation, surface functionalization, and hybrid composite formation. Fundamental adsorption mechanisms, redox processes, and photocatalytic behavior are discussed, with a focus on applications in water treatment (heavy metals, dyes, emerging contaminants). The article proposes an integrative structure–property–performance framework and explores emerging concepts such as sequential use and post-use valorization of saturated biochar. Challenges related to reproducibility, industrial scaling, life cycle assessment, and carbon accounting are analyzed. Finally, a SWOT analysis is presented that highlights the potential of modified biochar as a strategic material in the circular economy. Full article

The food packaging industry requires sustainable solutions to reduce plastic waste and replace synthetic additives. This study addresses the need for scalable methods to transform conventional polyethylene terephthalate (PET) packaging into active food preservation systems using natural biocides. Commercial PET packaging was surface-activated using industrial-scale corona treatment, followed by coating with natural biocides—carvacrol (CV) and trans-cinnamaldehyde (tCN). The resulting active packaging materials (PET-CV and PET-tCN) were characterized using XRD, FTIR, SEM, AFM, and desorption kinetics. Packaging properties including mechanical strength, oxygen barrier, antioxidant (DPPH), and antibacterial activity (against S. aureus and E. coli) were evaluated. Real-food preservation tests were conducted using fresh minced pork (4 °C, 6 days) and table olives (23 °C, 21 days), monitoring microbiological (TVC), colorimetric (CIE L*a*b*), and pH changes. Corona treatment successfully anchored both biocides through physical adsorption, with tCN exhibiting stronger surface interaction (desorption energy: 128.0 kJ/mol). Both coatings significantly improved oxygen barrier properties (61% reduction for PET-CV, 80% for PET-tCN). PET-tCN demonstrated superior antibacterial activity (inhibition zones: 15.0 mm against E. coli). In pork preservation, PET-tCN achieved a 2-log reduction in TVC, maintained meat redness (a*: 12.80 vs. 5.10 for control), and stabilized pH. For olives, PET-tCN reduced TVC by 2.35 log cycles and preserved green color. This corona-assisted coating approach, demonstrated here at laboratory scale, successfully transforms inert PET into multi-functional active packaging with potent antimicrobial, antioxidant, and barrier properties, significantly extending food shelf-life and offering a sustainable solution for reducing food waste. Full article

The sustainable management of olive wastes represents an important environmental challenge. Biochars and hydrochars derived from biomass are promising adsorbents for removing emerging pollutants from water. In the present work, olive stone wastes were converted into biochar and hydrochar by using pyrolysis (500 °C for 30 min) and hydrothermal carbonization (HTC) processes (220 °C for 10 h). Then, the obtained materials were physically activated by using CO₂ gas (750 °C for 30, 60 and 180 min). Various analytical techniques were applied for the chemical, textural and structural characterization of these carbonaceous materials (i.e., ultimate and proximate analysis, scanning electron microscopy (SEM), BET surface area, Raman spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy). Afterwards, the selected activated biochar and hydrochar were applied for the removal of amoxicillin from aqueous solutions. The experimental results show that the generated hydrochar has many microspheres on its surface and inside, while the produced biochar exhibits a porous structure with irregular forms. CO₂ physical activation has induced an important improvement of the biochar and hydrochar’s structural, textural, and surface chemistry properties. For instance, the activated biochar samples show a highly porous structure, with large specific surface areas that increase with the burn-off, reaching 1349.3 m² g⁻¹ following 3 h of activation. Regarding the activated hydrochar samples, they exhibit a spherical morphological structure with an important specific surface area, which increased to 846.7 m² g⁻¹ after 3 h of activation. Moreover, both activated materials have an amorphous structure with low oxygen surface groups. The selected novel CO₂-activated biochar and hydrochar efficiently remove amoxicillin from aqueous solutions under wide experimental conditions, with adsorption capacities of 386.4 and 215.9 mg g⁻¹, respectively. These efficiencies are higher than those reported for various activated biochars derived from lignocellulosic biomass, from sewage sludge, and from animal manure. Future research works are required to assess these materials’ effectiveness in treating real pharmaceutical effluents, to optimize the regeneration of the amoxicillin-loaded materials, and to design full-scale devices for a real application. Full article

Background/Objectives: Although triple antibiotic paste is effective in managing infected primary teeth, its incomplete removability from tooth structure remains a major limitation, prompting the search for alternative drug-delivery systems. The aim of this study was to obtain a multi-antibiotic porous composite system for tailored drug delivery, to develop a formulation strategy, and to characterize the physicochemical properties and drug release. Methods: The developed composites consisted of a porous composite matrix (PCM; chitosan/bioactive filler) and two or three antibiotics (ciprofloxacin [CIP], metronidazole [MET], clindamycin [CLI]). Three methods of incorporating antibiotics were used: applying an antibiotic solution to the stabilized PCM; introducing an antibiotic solution into the polymer matrix; and introducing an antibiotic into the polymer matrix as nanoparticles. The physicochemical properties of the composites, including microstructure, compressive strength, and swelling, were assessed. The antibiotic release profile was assessed for up to 168 h. Results: The most advantageous method for introducing MET and CLI, in terms of release profile, was applying them to the PCM surface, whereas ciprofloxacin exhibited stable release when incorporated directly into the polymer matrix and entrapped during the stabilization process. The composites with nanoparticles, including MET or CIP, did not release any active substances during the experimental period. Conclusions: The results demonstrate that the developed formulation strategy enables the production of composites that rapidly release substantial amounts of the active substances within a short time frame and maintain their concentration for an extended period, which may be beneficial for the treatment of bacterial infections. Full article

Metal–organic frameworks (MOFs) are unique microporous materials being explored for a wide range of applications. Their porosity and high surface areas can readily be exploited for guest–host interactions, separations, and photochemical catalysis, but many suffer from poor charge separation and fast electron–hole recombination. Introducing structural defects, such as missing linkers or metal nodes, can create unsaturated metal sites and alter band structure, conductivity, and light absorption, improving photocatalytic performance. UiO-66-NH₂ and MIL-125-NH₂ are water-stable, visible-light-absorbing MOFs well suited for photocatalytic degradation of organic dyes. In this work, the influence of defect engineering on photocatalytic properties of MOFs was investigated using formic and acetic acid modulators with UiO-66-NH₂ and variable temperature with MIL-125-NH₂ during synthesis. The resulting materials were characterized by XRD, FTIR and SEM/EDS. Defect states were tracked using N₂ adsorption/BET analysis and UV–Vis spectroscopy. Photocatalytic activity was evaluated by monitoring Rhodamine B (RhB) degradation in aqueous solution under simulated solar irradiation. It was found that increased temperature beyond 120 °C during synthesis promotes mesopore formation and decreases the bandgap in MIL-125-NH₂, resulting in a more photoactive material. Defective MIL-125-NH₂ synthesized at 150 °C showed the most defects and proved to be the best photocatalyst investigated in this study. Formic acid modulation in UiO-66-NH₂ generated smaller crystallites that slightly increased the bandgap; however, the surface area decreased proportionally with the amount of formic acid used. The decreased surface area and observed enhancement in photocatalytic degradation of RhB suggest that formic acid introduces defects into the UiO-66-NH₂ framework that enhance photocatalytic properties. UiO-66-NH₂ treated with acetic acid resulted in larger crystals, increased bandgaps, and increased surface areas, suggesting that acetic acid simply modulates growth rather than imparting defects to the framework. Full article

This study developed an active packaging material by incorporating tea tree oil (TTO)-loaded lotus stalk biochar (BC@TTO) into a chitosan (CS) matrix. Biochar was prepared from lotus stalks via pyrolysis at 600 °C and characterized, revealing a mesoporous structure with a specific surface area of 35.9 m²/g. Adsorption studies demonstrated that BC exhibited high affinity for TTO, following pseudo-first-order kinetics and the Langmuir isotherm model, with a maximum adsorption capacity of 295.6 mg/g. Chitosan-based composite membranes with varying BC@TTO contents (1–7 wt%) were fabricated by solution casting. The incorporation of BC@TTO significantly enhanced the tensile strength, elongation at break, barrier properties (water vapor and oxygen), and antioxidant/antibacterial activities of the membranes, with optimal performance observed at 3 wt% loading. However, higher loadings led to filler aggregation, reduced transparency, and compromised mechanical properties. In vitro release studies indicated that TTO release followed the Avrami model, suggesting a diffusion-controlled mechanism. Preservation tests on blueberries showed that the CS-3BC@TTO membrane effectively reduced weight loss and maintained fruit quality during storage. This work presents a promising strategy for designing bioactive packaging materials with sustained release functionality for food preservation applications. Full article

The aim of this study was to investigate which physicochemical and structural properties of cationic peptides P1–P6 may determine their selective anticancer activity against melanoma cells and their interactions with tumor cell membranes. An integrated approach was applied, including characterization in solution (osmotic pressure, NaCl stability, surface tension); cytotoxicity evaluation against Me45, B16F10, and HaCaT cells; analysis of interactions with phosphatidylglycerol (POPG) model membranes using isothermal titration calorimetry and steady-state fluorescence spectroscopy; membrane permeability assays; and F-actin staining. Anticancer activity depended on positively charged residues, hydrophobic amino acids, and sequence arrangement. Tryptophan-rich peptides P2 and P5 exhibited strong membrane interactions and high efficacy after 72 h. Highly hydrophobic P4, containing long C₁₂ chains with a relatively low net charge, caused nonselective lysis. P3 showed reduced activity due to insufficient amphipathicity, whereas P6, with excessive WWW and KKKK motifs, exhibited weak or nonselective effects. Thermodynamic and fluorescence analyses indicated that P2 and P5 initially bind POPG membranes via entropy-driven electrostatic interactions, followed by hydrophobic insertion of tryptophan residues, evidenced by increased fluorescence intensity and a blue shift of the emission maximum. P2, P4, and P5 induced actin cytoskeleton reorganization and increased membrane permeability, emphasizing the role of balanced amphipathicity and charge–hydrophobicity in designing selective anticancer peptides. Full article

Surface water–groundwater interactions within oasis–desert ecotones of arid regions play a pivotal role in sustaining regional water security and ecological stability. Taking the Niya River Basin in Xinjiang, Northwest China, as a representative inland watershed, this study systematically elucidates the mechanisms and seasonal dynamics of surface water–groundwater coupling under the combined influences of natural processes and anthropogenic activities. A total of 68 surface water and groundwater samples were collected during the dry, normal, and wet hydrological periods. Integrated hydrochemical characterization, mineral saturation index analysis, and stable isotope (δ²H and δ¹⁸O) mass balance modeling were employed to quantify recharge contributions and unravel hydrogeochemical evolution pathways. Results indicate that the waters in the study area are predominantly brackish to saline, with consistent dominant ionic assemblages (SO₄²⁻ and Na⁺) across all hydrological periods, highlighting evaporite dissolution as the primary control on solute composition. Hydrochemical evolution is jointly regulated by evaporation concentration, water–rock interactions, and cation exchange processes. Surface water chemistry reflects the combined effects of silicate weathering and evaporite dissolution, whereas groundwater chemistry is mainly governed by evaporite dissolution coupled with pronounced cation exchange. Stable isotope signatures reveal substantial secondary evaporation of regional precipitation prior to recharge. Frequent bidirectional recharge between surface water and groundwater was observed, exhibiting distinct seasonal transitions. During the dry period, groundwater provides significant baseflow support to surface water (48.6% in the oasis zone and 54.3% in the desert zone). In the normal period, recharge direction reverses, with surface water becoming the dominant source of groundwater recharge (99.0% in the oasis zone and 76.6% in the desert zone). In the wet period, spatial heterogeneity becomes evident: surface water continues to dominate groundwater recharge in the oasis zone (92.7%), whereas groundwater recharge to surface water prevails in the desert zone (50.5%). This study identifies a seasonally dynamic “discharge–infiltration–zonal regulation” bidirectional recharge pattern in arid inland river systems. The findings advance the mechanistic understanding of hydrological connectivity reconstruction within oasis–desert ecotones and provide a scientific basis for optimized regional water resource allocation and groundwater salinization risk mitigation. Full article

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have become a global environmental concern due to their extreme persistence and toxicity. In this study, perfluorooctanoic acid (PFOA) was removed from aqueous solutions using porous carbon adsorbents synthesized from peach stones. The novelty of this work lies in the development of a procedure for obtaining a suitable carbon adsorbent, whose properties are consistent with the properties of the adsorbate. An appropriate activation was used, allowing the preparation of an adsorbent with a highly developed porous texture and a large surface area, which is a prerequisite for a significant adsorption capacity of the obtained adsorbents towards PFOA. Both carbon adsorbents obtained from peach pits, with clearly different surface chemistry—KOH-activated carbon (AC_KOH) and its nitric acid-oxidized derivative (AC_HNO3)—for PFOA adsorption were compared, along with the clarification of the relationship between the graphitic structure, pore development, surface functionality and adsorption characteristics. The first adsorbent was produced by chemical activation with KOH at 800 °C, while the second was obtained by oxidative modification of the activated sample with 12% HNO₃. Characterization by Raman spectroscopy, SEM, and nitrogen physisorption revealed a highly graphitized structure (ID/IG = 0.86) and well-developed porosity. Adsorption experiments were carried out at PFOA concentrations from 8 to 40 µmol/L using a spectrophotometric method based on methylene blue ion-pair extraction into chloroform. The results showed that AC_KOH exhibited a high maximum adsorption capacity of 1660 µmol/g (687.36 mg/g) and followed the Langmuir isotherm model, indicating monolayer adsorption. In contrast, AC_HNO3 showed a significantly lower adsorption capacity of 398.36 µmol/g (164.95 mg/g), which was attributed to electrostatic repulsion caused by acidic oxygen-containing surface groups. These findings demonstrate that peach stone-derived activated carbon is a promising, sustainable, and efficient adsorbent for the removal of PFOA from water. Full article

This study presents a low-cost, small-scale single-chamber microbial fuel cell (MFC) toxicity biosensor fabricated on a printed circuit board (PCB) and a 3D-printed chamber with a volume of 120 μL. The anode consists of a screen-printed carbon electrode on the PCB, while the air cathode is a carbon paper electrode. To address poor adhesion of microorganisms to the smooth anode surface, femtosecond laser processing was used to fabricate a micropore array with 40 μm pores on the electrode. This method can create micropores on the anode surface without damaging the screen-printed electrodes, the PCB substrate, or the pads. These micropores increase the anode’s surface area and hydrophilicity, allowing more microbial coatings to firmly adhere to its surface. In this study, the MFC utilised Rhizobium rosettiformans W3, extracted from activated sludge at a wastewater treatment plant, as the anode microorganism. Its aerobic nature simplifies the design of MFCs, enabling a single-chamber structure and miniaturisation. Using formaldehyde solution as a toxicity sample to test the biosensor’s performance, a 0.1% concentration significantly reduced the sensor’s output power. Full article

Catalysis has entered everyday life through a range of technological processes that rely on different catalytic systems. The increasing demand for such systems requires rationalization of the use of their expensive components, such as noble-metal catalysts. As such, a catalyst with low noble-metal concentration, in which each one of the noble atoms is active, would reach the lowest price possible. Nevertheless, no clear reactivity descriptors have been outlined for this type of low-coordinated supported atom. Using DFT calculations, we consider three diverse systems as models of single-atom catalysts. We investigate monomers and bimetallic dimers of Ru, Rh, Pd, Ir, and Pt on MgO(001), Cu adatom on thin Mo(001)-supported films (NaF, MgO, and ScN), and single Pt adatoms on oxidized graphene surfaces. The reactivity of these metal atoms was probed by CO. In each case, we see the interaction through the donation–backdonation mechanism. In some cases, CO adsorption energies can be linked to the position of the d-band center and the adatom’s charge. A higher-lying d-band center and less-charged, supported single atoms bind CO more weakly. Also, in some cases, metal atoms that are less strongly bound to the substrate bind CO more strongly. The results suggest that the identification of common activity descriptor(s) for single metal atoms on foreign supports is a difficult task with no unique solution. However, it is also suggested that the stability of adatoms and strong anchoring to the support are prerequisites for the application of descriptor-based search to novel single-atom catalysts. Full article

Using pseudoboehmite and cerium nitrate as raw materials, a cerium dioxide-doped alumina support was prepared by the hot oil column method. Subsequently, with platinum nitrate and palladium nitrate solutions as precursor salts, the active components were loaded onto the supports via the incipient wetness impregnation, followed by an activation treatment, thus obtaining platinum-palladium bimetallic catalysts for hydrocarbon elimination in zero-air generators. The catalyst was characterized by XRD, BET, SEM, TEM, XPS, and Raman spectroscopy. The results showed that the as-prepared supports possess a large specific surface area, and the noble metals Pt and Pd are uniformly distributed on the support surface. After activation treatment, the structural stability and catalytic reaction activity of the catalysts are significantly enhanced. Performance tests simulating the actual operating conditions of zero-air generators show that the catalysts exhibit excellent hydrocarbon elimination capability: when the inlet methane concentration is 50 ppm, the outlet methane content can be reduced to below 10 ppb. Moreover, no obvious attenuation of catalyst activity is observed after a 1000-h long-term stability test, which meets the practical application requirements of zero-air generators. Full article

Traditional calcium hydroxide (Ca(OH)₂) typically exhibits low specific surface area and reactivity, significantly limiting its efficacy in industrial gas–solid reactions such as flue gas desulfurization and thermochemical energy storage. To address these limitations, this study proposes a two-stage synthesis strategy designed to enhance the surface properties and chemical activity of Ca(OH)₂. The process involves the preparation of high-activity calcium oxide (CaO), followed by controlled hydration using diethylene glycol (DEG). Drawing on established mechanisms from cement chemistry, wherein potassium ions (K⁺) catalyze the decomposition of calcium carbonate (CaCO₃), limestone particles (10–20 mm) were pre-soaked in a 0.1 mol/L potassium nitrate (KNO₃) solution for 48 h prior to calcination. Characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Blaine Air Permeability Method analysis revealed that this pretreatment accelerated decomposition kinetics by inducing surface defects, yielding CaO with a maximum reactivity of 435.7 mL. Subsequent hydration at 80 °C with 70 wt% DEG effectively suppressed particle agglomeration and promoted the formation of thin platelet structures. The resulting Ca(OH)₂ achieved a utilization efficiency of 98.5% and a specific surface area of 43.24 m²/g, demonstrating a robust technical route for fabricating high-performance calcium-based sorbents for environmental and energy applications. Full article

Boriding is a thermochemical process that improves the surface properties of metallic materials, such as wear resistance, hardness, and Young’s modulus. The current work evaluated the kinetics of boride layers formed by boriding on AISI H13 steel. The AISI H13 steel samples were covered with a non-commercial powder mixture of 70% wt. SiC, 20% B₄C wt. and 10% wt. KBF₄. The samples were treated for 2, 4, and 6 h at 850, 875, and 900 °C, respectively. The growth kinetics of boride layers were estimated as a function of the treatment parameters, using a solution of the second Fick’s Law, as in a parabolic model. Also, the hardness of layers was assessed by Vickers microindentation. Optical examination of the samples showed a biphasic FeB/Fe₂B layer at all temperatures after 6 h of treatment. In contrast, those exposed for 2 h exhibited a monophasic Fe₂B layer with isolated zones of the FeB phase in all temperatures. The results suggested that the obtained layer thicknesses are highly dependent on the treatment parameters. After 2 h at 850 °C, the samples exhibited a well-defined layer with a thickness of 8.51 ± 1.01 μm, whereas after 6 h it was 24.39 ± 1.01 μm. The activation energy was estimated at 230.63 kJ/mol, with a correlation coefficient (R2) of 0.97, consistent with values reported in the literature. Additionally, the hardness values were estimated to range from 1880 to 2192 HV for the FeB phase and from 1294 to 1715 HV for the Fe₂B phase, indicating that the hardness of the boride layers is highly dependent on the treatment conditions. Full article

The travertine formed through the precipitation of supersaturated calcium carbonate from geothermal or surface waters due to CO₂ degassing, evaporation, and biological activities not only exhibits remarkable landscape value but also holds significant scientific importance in geological research. Current conservation efforts face critical challenges including travertine degradation, increased algal biomass accumulation, and progressive marshification processes. The study focused on how Vallisneria natans (V. natans) and Ceratophyllum demersum (C. demersum) affected travertine deposition. Analyzing the physical and chemical parameters, phase structure, crystal morphology, and microbial community in the aquatic environment, it was observed that under conditions of low c (Ca²⁺) concentration in solution (≤100 mg L⁻¹), both species significantly increased the rate of travertine deposition. The effect of plant biomass was species-specific: V. natans showed the highest promotion at 70 g L⁻¹, while C. demersum performed effectively at moderate biomass levels (140 and 280 g L⁻¹). Specifically, C. demersum exhibited enhanced photosynthetic activity, elevated pH, increased dissolved oxygen (DO) content and more epibiotic microorganisms, with higher levels of Aeromonas compared to V. natans. Therefore, C. demersum demonstrated a greater capacity for travertine deposition. However, the culture environment with elevated c (Ca²⁺) ≥ 500 mg L⁻¹ or higher biomass levels (420 g L⁻¹) impeded the stable growth of submerged plants and exerted a stress effect on them, hindering travertine deposition. The morphology of travertine crystals promoted by the two submerged macrophytes was distinct. In the V. natans treatment, the crystals were square and elongated, whereas in the C. demersum treatment, they were spheraragonite, droplet-like, and petal-shaped. This study reveals the mechanisms by which submerged macrophytes promote travertine deposition and provides new insights for adopting nature-based ecological restoration strategies to sustainably maintain travertine landscapes. By leveraging the promoting effects of submerged macrophytes, travertine deposition and the aquatic environment were improved while reducing energy and chemical inputs. Such biological regulation approaches help synergistically achieve the dual objectives of geological heritage conservation and ecosystem health restoration. Full article