Search Results (656)

Carbonaceous sorbents were prepared from Chlorella vulgaris via hydrothermal carbonization (200 °C and 250 °C) and slow pyrolysis (300–500 °C) to assess their effectiveness in removing the herbicide metribuzin from water. The biomass was cultivated under controlled laboratory conditions, allowing for consistent feedstock quality and traceability throughout processing. Using a single microalgal feedstock for both thermal methods enabled a direct comparison of hydrochar and pyrochar properties and performance, eliminating variability associated with different feedstocks and allowing for a clearer assessment of the influence of thermal conversion pathways. While previous studies have examined algae-derived biochars for heavy metal adsorption, comprehensive comparisons targeting organic micropollutants, such as metribuzin, remain scarce. Moreover, few works have combined kinetic and isotherm modeling to evaluate the underlying adsorption mechanisms of both hydrochars and pyrochars produced from the same algal biomass. Therefore, the materials investigated in the present work were characterized using a combination of standard physicochemical and structural techniques (FTIR, SEM, BET, pH, ash content, and TOC). The kinetics of sorption were also studied. The results show better agreement with the pseudo-second-order model, consistent with chemisorption, except for the hydrochar produced at 250 °C, where physisorption provided a more accurate fit. Freundlich isotherms better described the equilibrium data, indicating heterogeneous adsorption. The hydrochar obtained at 200 °C reached the highest adsorption capacity, attributed to its intact cell structure and abundance of surface functional groups. The pyrochar produced at 500 °C exhibited the highest surface area (44.3 m²/g) but a lower affinity for metribuzin due to the loss of polar functionalities during pyrolysis. This study presents a novel use of Chlorella vulgaris-derived carbon materials for metribuzin removal without chemical activation, which offers practical benefits, including simplified production, lower costs, and reduced chemical waste. The findings contribute to expanding the applicability of algae-based sorbents in water treatments, particularly where low-cost, energy-efficient materials are needed. This approach also supports the integration of carbon sequestration and wastewater remediation within a circular resource framework. Full article

In this study, flotation tests were conducted on a laboratory scale using a sample of microcrystalline graphite ore from the Canindé region, Ceará, Brazil. The objective was to investigate the grinding time, reagent dosage, and purification process for obtaining graphene-based nanomaterials. Natural graphite has a stacked planar structure and exhibits polymorphism with rhombohedral, hexagonal, and turbostratic geometries, characteristics that directly influence its properties and technological applications. The results demonstrated that it was possible to obtain rougher concentrate with a graphite carbon content of 23.4% and a recovery of 86.4%, using a grinding time of 7.5 min and reagent dosages of 150 g/t of kerosene and 100 g/t of Flotanol D-25. This flotation process resulted in a graphite concentrate with 76.6% graphite carbon content. To increase the purity of the concentrate and expand its industrial applications, the graphite was purified in an alkaline autoclave using the hydrothermal method. In the next stage, acid leaching was performed, and this chemical treatment destabilized the regular stacking of the graphite layers, promoting the formation of graphene-like nanoplates, including monolayer graphene. Thus, the nanomaterials obtained through the process developed in this study have potential for various innovative applications, such as lithium-ion batteries, electric vehicles, and two-dimensional graphene-based materials. Full article

Since its discovery, laser-induced graphene (LIG) has attracted much interest because this technique, having all the advantages of a laser processing technology, is more convenient and cost-effective than other graphene production methods. This work offers a detailed analysis of LIG structures produced by UV and CO₂ laser irradiation from polyimide performed with surface scanning Raman spectroscopy combined with microscopy techniques. Although UV LIG has a less ordered structure than that obtained by CO₂ laser irradiation, our study indicates that UV LIG can be patterned with a resolution higher than that obtained with CO₂ laser irradiation and a much smaller penetration depth into the substrate. Full article

This study explores the use of carbon materials derived from Nocino walnut liqueur pomace residue for the removal of chlorpyrifos, a widely used organophosphate pesticide, from water. Carbon adsorbents were synthesized from young walnut biomass under different thermal and chemical treatment conditions, and their structural and surface properties were characterized using BET analysis, FTIR, SEM-EDX, Boehm titration, and zeta potential measurements. The materials exhibited distinct textural and chemical features, including high surface areas and varied surface functionalizations. Batch adsorption studies revealed that the chlorpyrifos removal followed pseudo-second-order kinetics and was best described by the Freundlich and Langmuir isotherms, indicating a combination of pore filling and physisorption via π-π and van der Waals interactions. The highest adsorption capacity of 45.2 ± 0.2 mg g⁻¹ was achieved at 30 °C. Thermodynamic analysis confirmed the process to be endothermic, spontaneous, and entropy-driven, with desolvation effects enhancing the performance at elevated temperatures. Dynamic filtration experiments validated the practical applicability of the materials, while moderate reusability was achieved through ethanol-based regeneration. These findings demonstrate the potential of walnut pomace-derived carbons as low-cost, renewable, and effective adsorbents for sustainable water decontamination. Full article

In this work, we report the evaluation of a (CuO/WO₃)-CuWO₄ heterostructured system as a methanol and acetone gas sensor in different configurations, contrasted with the pure oxides CuO and WO₃. The samples were synthesized using a modified precipitation route followed by a single thermal treatment step to induce multiphase simultaneous crystallization. The structural characterization by XRD showed that all the materials presented the formation of monoclinic CuO and WO₃ and triclinic CuWO₄. No additional phases were detected in the samples, and a reduction in the crystallite size of the CuO phase after the crystallization in the heterostructured system was observed. FE-SEM analysis made it possible to directly observe the morphology and the structures of the samples at the nanometer scale, showing a heterogeneous grain formation and supporting the formation of a heterostructure. UV-Vis DRS was used to study the optical properties of the materials, and the presence of two optical band gaps was successfully determined, which provides further evidence of heterostructure formation via this modified synthesis route. The variation in the resistance of the materials was observed in the presence of methanol and acetone vapors, where the heterostructure exhibited a substantial change in performance in the configuration with 40% copper precursor (Cu40:W60), the sample that presented the highest response as a sensor against these VOCs. To our knowledge, this is the first time that this system has been reported as a gas sensor, using the multiple configurations of the (CuO/WO₃)-CuWO₄ heterostructured system. Full article

Significant improvements in the tribological performance of graphene-doped additively manufactured structures are reported, with absolute values of friction coefficients reaching 0.09 corresponding to ca. 70% decreases from plain/un-doped samples. The findings highlight an impressive potential of the nanocarbon variant, to endow superior tribological performance to polymers, bringing them a step closer to the ideal superlubric regime. Such structures of intrinsic superlubric performance are envisioned as viable candidates for the containment of great amounts of energy, currently wasted as friction in a plethora of applications, hence also promoting an ecologically sustainable development. Indications that superlubricity is greatly promoted by nanocarbons, especially by the two-dimensional variant of graphene with excellent response in shear action, are investigated in combination with the effect of surface topography, for the investigation of the tribological performance of three-dimensional structures with geometric surface patterning, additively manufactured from graphene-doped polymers. Spectroscopic, mechanical, and microstructural characterization of plain polymer-based samples and their graphene-enhanced nanocomposite counterparts was followed by tribometric measurements for the establishment of the evolution of the friction coefficient on a certified commercial tribometer operating under the ball-on-disk configuration as well as on a conceptual purpose-built setup. The individual and combined effects of nanomaterial presence and patterning are reported, and the influence of manufacturing-prone micropatterning is examined. Full article

Diamond, known for its exceptional physical and chemical properties, shows great potential in advanced fields such as medicine, semiconductors, and optics. However, reducing surface roughness is critical for enhancing its performance. This study employs inductively coupled plasma (ICP) polishing to etch single-crystal diamond and analyzes the impact of different etching parameters on surface roughness using atomic force microscopy (AFM). Using the change in surface roughness before and after etching as the main evaluation metric, the optimal etching parameters were determined: Ar/O₂/SF₆ gas flow ratio of 40/50/10 sccm, ICP power of 200 W, RF bias power of 40 W, chamber pressure of 20 mTorr, and etching time of 10 min. Results show that increased etching time and SF₆ flow rate raise surface roughness; although higher ICP and RF power reduce roughness, they also cause nanostructure formation, affecting surface quality. Lower chamber pressure results in smaller roughness increases, while higher pressure significantly worsens it. Based on the optimized process parameters, the pristine single-crystal diamond was further etched in this study, resulting in a significant reduction of the surface roughness from 2.22 nm to 0.562 nm, representing a 74.7% decrease. These improvements in surface roughness demonstrate the effectiveness of the optimized process, enhancing the diamond’s suitability for high-precision optical applications. Full article

In this article, we present a high-sensitivity narrow-band perfect graphene absorber that exhibits excellent tunability across multiple bands. The top layer of the absorber unit is composed of graphene material, and the shape is a square graphene layer with a ring structure and a square structure removed from the middle. A SiO₂ dielectric layer is located in the middle, and a layer of gold substrate exists at the bottom. This structure has generated five perfect absorption peaks at 6.08216 THz, 7.29058 THz, 9.34669 THz, 11.5471 THz, and 13.0441 THz, and the levels of absorption are 98.24%, 98.03%, 99.55%, 98.87%, and 99.99%, respectively. We have proved the advantages of our model by comparing the influence of different shapes of graphene on the absorption rate of the model. Then, we changed the relaxation time and Fermi energy level of graphene and other factors such as the refractive index to prove that our structure has good tunable performance. Finally, we calculated the sensitivity, and the sensitivity of this structure is as high as 4508.75 GHZ/RIU. Compared with previous articles, our article has more absorption peaks, a higher absorption efficiency, and a higher sensitivity. The absorber proposed in this paper shows great potential to contribute to high-sensitivity sensors, photoelectric detection, photoelectric communication, and other related fields. Full article

Electrically conductive composites of ultra-high molecular weight polyethylene (UHMWPE) may be of interest as strain sensors for event detection in high-strain scenarios, with potential applications in ballistics or orthopedics. In this study, geometric deformations of electrically conductive composites of UHMWPE were quantified for large plastic strains via physical measurements. These measurements were compared to neat (non-composite) control materials, and to geometrical behaviors predicted under volume conservation assumptions. This study found that material geometry remained close to that predicted by volume conservation at low-to-moderate plastic strains, with differences exceeding 5% only above 100% nominal strain. Materials with higher filler loading experienced a greater increase in measured volume than neat controls, particularly at higher strains. The results suggest that this difference could be due in part to volumetric opening in the composite materials with high filler loading. Finally, necking behavior was observed and quantified in this study, presenting another effect that should be taken into account for future work characterizing the electrical behavior of these materials under large plastic deformations. The results of this study thus lay the foundation for further characterization of these electrically-conductive composites, and to determine their intrinsic electrical properties as a function of strain in particular. Full article

Our first-principles calculations have unveiled a profound influence of varied external charges on the energy levels and spin distributions of zero-, one-, and two-dimensional carbon nanomaterials. By leveraging the Fermi distribution formula, we systematically analyze the temperature-dependent electron occupancy probabilities of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Notably, configurations with specific additional electron loads exhibit a stable total occupancy of HOMO + LUMO equal to 1 across a wide temperature range, forming a robust basis for orbital qubits. This stability persists even under Fermi energy corrections, demonstrating minimal temperature sensitivity up to 300 K. Furthermore, we identify a universal criterion—E_HOMO + E_LUMO = 2E_Fermi—that governs qubit feasibility across diverse carbon nanostructures, independent of dimensionality or atom count. Experimental validation via charge injection methods (e.g., gate modulation or electron beam irradiation) is supported by existing precedents in carbon-based quantum devices. Our findings establish low-dimensional carbon nanomaterials as versatile, scalable platforms for quantum computing, combining thermal stability and dimensional adaptability, thus bridging theoretical insights with practical quantum engineering. Full article

Solar interface evaporation is a promising technology for sustainable freshwater acquisition. Regulating the hydrophilicity/hydrophobicity of the evaporator can optimize the water transport, heat transfer, and evaporation enthalpy during the evaporation process, thereby significantly improving the evaporation performance. The CoSe/Co-SeC nanoflower was prepared by high-temperature selenization of ZIF-67. Each petal of the nanoflower is loaded with a density-gradient distribution CoSe/Co, forming an uneven hydrophilic and hydrophobic surface that transitions from bottom hydrophilicity to top hydrophobicity. During the evaporation process, the hydrophilic bottom of the petals promotes rapid water supply, while the hydrophobic top of the petals protrudes from the water surface to form a large number of solid–liquid–gas three-phase interfaces. Therefore, water clusters activated by the strong hydrophilic sites at the bottom of the petals can reach the gas–liquid interface after a very short transmission distance and achieve water cluster evaporation. In addition, the nanoflower optimized the heat transfer at the solid–liquid interface and further promoted the increase in evaporation rate through micro-meniscus evaporation (MME). As a result, the evaporation rate and energy efficiency of the CoSe/Co-SeC evaporator are as high as 2.44 kg m⁻² h⁻¹ and 95.5%. This work passes controllable preparation of the gradient CoSe/Co-SeC and shows the enormous potential of micro-hydrophobic and hydrophilic regulation for improving solar interface evaporation performance. Full article

Graphene oxide (GO), owing to its extraordinary application prospects in biomedicine, is attracting growing research attention. However, the biosafety and blood compatibility of GO required for its clearance for use in clinical trials remain elusive. Therefore, we studied the mutagenic properties of GO as well as its cell toxicity and blood compatibility. Prior to biological experiments, we assessed the structural organization of GO using dynamic light scattering and microscopic visualization methods. The results of both the Ames mutagenicity test performed on Salmonella enterica serovar Typhimurium TA98 and TA102 strains and the cytotoxicity test on noncancerous, immortalized human keratinocytes revealed no mutagenic or toxic effects of GO. Simultaneously, GO reduced the viability of the MelJuSo human melanoma cell line. A blood compatibility assay revealed that a concentration of 10 μg/mL was critical for GO biosafety, as greater concentrations induced diverse side effects. Specifically, GO disrupts erythrocytes’ membranes in the dose-dependent manner. Moreover, GO at higher concentrations both inhibited the process of ADP (a physiological platelet agonist)-induced cell aggregation and affected their disaggregation process in platelet-rich plasma. However, in the blood clotting assessment, GO showed no effects on the activated partial thromboplastin time, prothrombin time, or thrombin time of the platelet-poor plasma. The obtained results clearly indicate that the relationship between the GO preparation method, its size, and concentration and biosafety must be cautiously monitored in the context of further possible biomedical applications. Full article

Nitrogen-doped graphene quantum dots (NGQDs) are made by heating a mixture of GQDs and ammonia using a thermochemical method. The optical properties of the samples were studied. Here, the role of the temperature used in the annealing process is investigated. It is found that with the increase in heating temperature, the sp² fraction content continuously increases, and the photoluminescence (PL) blue shift continuously increases. The 550 nm peak of GQDs shifts from 550 nm to 513 nm NGQDs synthesized at 300 °C. The normalized PL intensity shows a significant blue shift in the emission peak of the NGQD samples compared to the GQDs. The peak position of the GQDs is 555 nm, while the peak positions of the NGQDs are 511 nm for NGQDs-250, 488 nm for NGQDs-300, and 480 nm for NGQDs-350. Using a simple thermochemical method, we can effectively dope N into GQDs, and it is evident from the electron energy loss spectra that N doping induces the emergence of a new energy level in the electronic structure, which alters the optical properties of NGQDs. Full article

Wool textiles with multifunctional properties such as self-cleaning, antibacterial, electrical conductivity, UV blocking etc. have recently attracted interest. Among the materials employed towards their development, carbon nanotubes (CNTs) have been widely investigated due to their unique chemical, mechanical and electrical properties, exhibiting also notable UV-blocking properties. However, their limited dispersibility in solvents, particularly in water, has hindered their extensive industrial application and diminished their significant potential. In this work, two guanidinylated derivatives of hyperbranched polyethyleneimine (GPEI5k and PEI 25K) functionalized oxCNTs (oxCNTs@GPEI5K and oxCNTs@GPEI5K), with exceptional aqueous compatibility and colloidal stability, developed in our recent publication, were evaluated as to their antibacterial activity on Gram (-) Escherichia coli and Gram (+) Staphylococcus aureus bacteria and their cytotoxicity against mammalian cells, and the most promising, i.e., oxCNTs@GPEI5K, was subsequently used as finishing agent of wool fabric. The resulting wool textiles were evaluated for color, wash fastness, antibacterial properties, and UV-blocking performance. The GPEI-functionalized oxCNTs derivative, exhibited uniform distribution and good adhesion onto the wool fabrics yielding multifunctional wool fabrics with sustained antibacterial properties even after multiple washing cycles. Additionally, the modified textiles exhibited improved ultraviolet protection, highlighting their potential for multifunctional applications in antibacterial and UV-shielding textiles. Full article

Over the past few decades, awareness has risen substantially about the limitations of non-renewable resources and the environmental challenges facing the chemical industry. This has necessitated a transition toward renewable resources, such as lignocellulosic biomass, which is among the most abundant renewable carbon sources on the planet. Lignocellulosic biomass represents a significant yet often underutilized source of fermentable sugars and lignin, with potential applications across multiple sectors of the chemical industry. The formation of humins (polymeric byproducts with a complex conjugated network, comprising furanic rings and various functional groups, including ketones) occurs inevitably during the hydrothermal processing of lignocellulosic biomass. This study presents the use of humin byproducts derived from soybean peels for the production of fluorescent carbon dots (CDs). A comparison between sonochemical and thermochemical methods was conducted for the synthesis of this nanomaterial. The obtained nanoparticles were characterized in terms of size, morphology (TEM, DLS), and Z-potential. Subsequently, the spectroscopic properties of the prepared CDs were studied using absorption and emission spectroscopy. In particular, the CDs displayed a blue/cyan fluorescence under UV irradiation. The emission properties were found to be dependent on the excitation wavelength, shifting to longer wavelengths as the excitation wavelength increased. The carbon dots that exhibited the most favorable photochemical properties (QY = 2.5%) were those produced through a sonochemical method applied to humins obtained from the dehydration of soybean husks with phosphoric acid and prior treatment. Full article