Search Results (502)

Electrostatic adsorption plays a crucial role in nanoparticle-based drug delivery, enabling the targeted and reversible loading of biomolecules onto nanoparticles. This review explores the fundamental mechanisms governing nanoparticle–biomolecule interactions, with a focus on electrostatics, van der Waals forces, hydrogen bonding, and protein corona formation. Various functionalization strategies—including covalent modification, polymer coatings, and layer-by-layer assembly—have been employed to enhance electrostatic binding; however, each presents trade-offs in terms of stability, complexity, and specificity. Emerging irradiation-based techniques offer potential for direct modulation of surface charge without the addition of chemical groups, yet they remain underexplored. Accurate characterization of biomolecule adsorption is equally critical; however, the limitations of individual techniques also pose challenges to this endeavor. Spectroscopic, microscopic, and electrokinetic methods each contribute unique insights but require integration for a comprehensive understanding. Overall, a multimodal approach to both functionalization and characterization is essential for advancing nanoparticle systems toward clinical drug delivery applications. Full article

Sustainable deepwater drilling for oil and gas offers significant potential. In this work, we synthesized a nanoscale collapse-prevention agent by grafting didecyldimethylammonium chloride onto spherical nano-silica and characterized it using Fourier-transform infrared spectroscopy, thermogravimetric analysis, zeta-potential, and particle-size measurements, as well as SEM and TEM. Adding 1 wt% of this agent to a bentonite slurry only marginally alters its rheology and maintains acceptable low-temperature flow properties. Microporous-membrane tests show filtrate passing through 200 nm pores drops to 55 mL, demonstrating excellent plugging. Core-immersion studies reveal that shale cores retain integrity with minimal spalling after prolonged exposure. Rolling recovery assays increase shale-cutting recovery to 68%. Wettability tests indicate the water contact angle rises from 17.1° to 90.1°, and capillary rise height falls by roughly 50%, reversing suction to repulsion. Together, these findings support a synergistic plugging–adsorption–hydrophobization mechanism that significantly enhances wellbore stability without compromising low-temperature rheology. This work may guide the design of high-performance collapse-prevention additives for safe, efficient deepwater drilling. Full article

The development of efficient and sustainable water recycling systems is essential for long-term human missions and the establishment of space habitats on the Moon, Mars, and beyond. Humidity condensate (HC) is a low-strength wastewater that is currently recycled on the International Space Station (ISS). The main contaminants in HC are primarily low-molecular-weight organics and ammonia. This has caused operational issues due to microbial growth in the Water Process Assembly (WPA) storage tank as well as failure of downstream systems. In addition, treatment of this wastewater primarily uses adsorptive and exchange media, which must be continually resupplied and represent a significant life-cycle cost. This study demonstrates the integration of a membrane-aerated biological reactor (MABR) for pretreatment and storage of HC, followed by brackish water reverse osmosis (BWRO). Two system configurations were tested: (1) periodic MABR fluid was sent to batch RO operating at 90% water recovery with the RO concentrate sent to a separate waste tank; and (2) periodic MABR fluid was sent to batch RO operating at 90% recovery with the RO concentrate returned to the MABR (accumulating salinity in the MABR). With an external recycle tank (configuration 2), the system produced 2160 L (i.e., 1080 crew-days) of near potable water (dissolved organic carbon (DOC) < 10 mg/L, total nitrogen (TN) < 12 mg/L, total dissolved solids (TDS) < 30 mg/L) with a single membrane (weight of 260 g). When the MABR was used as the RO recycle tank (configuration 1), 1100 L of permeate could be produced on a single membrane; RO permeate quality was slightly better but generally similar to the first configuration even though no brine was wasted during the run. The results suggest that this hybrid system has the potential to significantly enhance the self-sufficiency of space habitats, supporting sustainable extraterrestrial human habitation, as well as reducing current operational problems on the ISS. These systems may also apply to extreme locations such as remote/isolated terrestrial locations, especially in arid and semi-arid regions. Full article

The separation of particles smaller than 1 µm either by composition or by size is still a challenge. For the separation of SiO₂ and SnO₂, the creation of a selective separation feature and the specific adsorption of salts and surfactants were investigated. The adsorption of various salts, e.g., AlCl₃, ZnCl₂, MnCl₂ and MgCl₂ were therefore analyzed, and the necessary concentration for the charge reversal of the material was determined. It was noticed that the investigated materials differ in their isoelectric point (IEP) and therefore in their adsorption behavior because only ZnCl₂ and MgCl₂ are suitable for a charge reversal of both metal oxides. The phase transfer of the pure material at different pH values with ZnCl₂ or MgCl₂ and sodium dodecyl sulfate (SDS) revealed that the adsorption behavior of the particle has an influence on the phase transfer. As a result, the phase transfer of SiO₂ is pH dependent, whereas the phase transfer of SnO₂ operates over a wider pH range. This allowed the separation of SiO₂ and SnO₂ to be controlled by the salt and surfactant concentration as well as pH. The separation of SiO₂ and SnO₂ was investigated for various parameters such as salt and surfactant concentration, particle concentration and composition of the mixture. Also, pH 8, where a selective phase transfer for SiO₂ occurs, and pH 6, where the greatest difference between the materials exists, were also investigated. By comparing the parameters, it was found that the combination of ZnCl₂/SDS and MgCl₂/SDS enables a selective separation of the materials. Furthermore, it was also found that the concentration of SDS has a significant effect on the separation, as the formation of a bilayer structure is important for the separation, and therefore, higher SDS concentrations are required at higher particle concentrations to increase the separation efficiency. Full article

Lithium–sulfur (Li-S) batteries are hindered by the sluggish electrochemical kinetics and poor reversibility of lithium polysulfides (LiPSs), which limits their practical energy density and cycle life. In order to address this issue, a novel Ni₃N/Nb₄N₅ heterostructure was synthesized via electrospinning and nitridation as a functional coating for polypropylene (PP) separators. Adsorption experiments were conducted in order to ascertain the heterostructure’s superior affinity for LiPSs, thereby effectively mitigating their shuttling. Studies of Li₂S nucleation demonstrated the catalytic role of the substance in accelerating the deposition kinetics of Li₂S. Consequently, Li-S cells that employed the Ni₃N/Nb₄N₅-modified separator were found to achieve significantly enhanced electrochemical performance, with the cells delivering an initial discharge capacity of 1294.4 mAh g⁻¹ at 0.2 C. The results demonstrate that, after 150 cycles, the cells retained a discharge capacity of 796.2 mAh g⁻¹, corresponding to a low capacity decay rate of only 0.25% per cycle. In addition, the rate capability of the cells was found to be improved in comparison to control cells with NiNb₂O₆-modified or pristine separators. Full article

Landfill leachates in tropical regions represent a critical environmental challenge due to their complex composition and pronounced seasonal variability. This study sought to characterize leachates from a tropical landfill in Valledupar, Colombia, and to evaluate advanced treatment technologies for the removal of organic pollutants. An ARIMA (3,0,3) model was implemented on an eight-year time series (2016–2023) of leachate flow data to identify seasonal patterns and support hydraulic load forecasting. Physicochemical characterization was conducted following APHA standard methods, which revealed high levels of COD, BOD₅, chlorides, and lead. Two treatment technologies were assessed independently: (i) adsorption using granular activated carbon in batch and continuous-flow systems, under 36 experimental conditions that combined pH levels (2–7) and carbon dosages (20–120 g); and (ii) reverse osmosis employing polyamide membranes operated at 18 bar and at pH values of 6.0, 7.0, and natural (unaltered) conditions. The results confirmed that leachate generation exhibits clear seasonal variability correlated with rainfall patterns. The Langmuir isotherm demonstrated the best fit at pH 4.0 (R² = 0.9685), and the continuous system achieved 97% COD removal within 90 min. Reverse osmosis consistently removed over 94% of COD and BOD₅ across all pH conditions. These findings highlight the value of integrating time-series forecasting with optimized treatment technologies to support effective and adaptive leachate management strategies in tropical environments. Full article

Electrocatalytic urea synthesis offers great potential for sustainable strategies through CO₂ and NO₃⁻ reduction reactions. However, the development of high-performance catalysts is often hampered by the complexity of synthetic methodologies and the unresolved nature of C-N coupling pathways. In this study, we present a copper–indium co-doped titanium dioxide (CuIn-TiO₂) catalyst that exhibits remarkable efficacy in enhancing the synergistic reduction of CO₂ and NO₃⁻ to produce urea. The bimetallic CuIn site functions as the primary active site for the C-N coupling reaction, achieving a urea yield rate of 411.8 μg h⁻¹ mg_cat⁻¹ with a Faradaic efficiency of 6.7% at −0.8 V versus reversible hydrogen electrode (vs. RHE). A body of experimental and theoretical research has demonstrated that the nanoscale particles enhance the density of active sites and improve the feasibility of reactions on the surface of TiO₂. The co-doping of Cu and In has been shown to significantly enhance electronic conductivity, increase the adsorption affinity for *CO₂ and *NO₃⁻, and promote the C-N coupling process. The CuIn-TiO₂ catalyst has been demonstrated to effectively promote the reduction of NO₃⁻ and CO₂, as well as accelerate the C-N coupling reaction. This effect is a result of a synergistic interaction among the catalyst’s components. Full article

In this study, we develop a graphene-trenched silicon Schottky junction for humidity sensing. This novel structure comprises suspended graphene bridging etched trenches on a silicon substrate, creating both free-standing and substrate-contacting regions of graphene that enhance water adsorption sensing. Suspended graphene is intrinsically insensitive to water adsorption, making it difficult for adsorbed H₂O to effectively dope the graphene. In contrast, when graphene is supported on the silicon substrate, water molecules can effectively dope the graphene by modifying the silicon’s impurity bands and their hybridization with graphene. This humidity-induced doping leads to a significant modulation of the Schottky barrier at the graphene–silicon interface, which serves as the core sensing mechanism. We investigate the current–voltage (I–V) characteristics of these devices as a function of trench width and relative humidity. Our analysis shows that humidity influences key device parameters, including the Schottky barrier height, ideality factor, series resistance, and normalized sensitivity. Specifically, larger trench widths reduce the graphene density of states, an effect that is accounted for in our analysis of these parameters. The sensor operates under both forward and reverse bias, enabling tunable sensitivity, high selectivity, and low power consumption. These features make it promising for applications in industrial and home safety, environmental monitoring, and process control. Full article

This study investigates the adsorption and desorption efficiencies of Cu (II) and Cd (II) from industrial effluents using orange peel powder and a newly developed mixed adsorbent composed of equal parts of activated charcoal (AC) and bone charcoal (BC). The mixed adsorbent (AC + BC) exhibited significantly higher removal efficiencies for both copper and cadmium metal ions compared to orange peel powder. This can be attributed to the high surface area of AC and the negative surface charge of BC, resulting in a synergistic adsorption effect. Batch adsorption experiments were conducted in an orbital shaker at 150–180 rpm for 60 min, followed by thorough rinsing to remove any residual metal ions. The optimal pH for maximum adsorption of Cu (II) and Cd (II) was found to be 6. The effects of adsorbent dosage (ranging from 0.5 to 5 g/L) and contact time (ranging from 15 min to 4 h) on adsorption performance were systematically studied. Regeneration experiments using 0.2 M HCl demonstrated that the adsorption of Cu (II) and Cd (II) on the mixed adsorbent was highly reversible, achieving desorption efficiencies of 90% and 94%, respectively. Notably, Cd (II) consistently exhibited higher desorption rates across all tested dosages. These results confirm the potential of the proposed adsorbent and regeneration strategy for efficient and economical removal of heavy metals from industrial wastewater. Full article

Histone deacetylase 11 (HDAC11), the sole member of class IV HDACs, has gained prominence due to its unique enzymatic profile and pathological relevance in cancer, neurodegenerative, inflammatory diseases, and metabolic disorders. However, only a limited number of selective HDAC11 inhibitors have been identified, and many of these contain a potentially mutagenic hydroxamic acid as a zinc-chelating motif. Consequently, there is an imperative to identify potent and selective non-hydroxamate HDAC11 inhibitors with improved physicochemical properties. In this study, we conducted an extensive experimental high-throughput screening of 10,281 structurally diverse compounds to identify novel HDAC11 inhibitors. Two promising candidates, caffeic acid phenethyl ester (CAPE) and compound 9SPC045H03, both lacking a hydroxamic acid warhead, were discovered, showing micromolar inhibitory potency (IC₅₀ = 1.5 and 2.3 µM, respectively), fast and reversible binding, and remarkable isozyme selectivity. Molecular docking revealed distinct zinc-chelating mechanisms involving either carbonyl oxygen (CAPE) or pyridine nitrogen (9SPC045H03), in contrast to canonical hydroxamates. Both compounds are drug-like and exhibit favorable physicochemical and pharmacokinetic profiles, particularly beneficial water solubility and good adsorption, making them valuable starting points for further optimization. These findings open new avenues for the development of selective, non-hydroxamate HDAC11 inhibitors with potential therapeutic applications. Full article

Fine spodumene particles are challenging to treat by froth flotation and are often discarded. An approach to recover the lithium-bearing mineral is to selectively aggregate fine spodumene into larger sizes that are amenable to recovery by flotation. This research investigated the aggregation behaviour of spodumene and the gangue minerals K-feldspar and quartz, using commercially available anionic polyacrylamide flocculants. Calcium ions were used as activators that facilitated the selective adsorption of the carboxylate groups in the anionic flocculants onto the spodumene surface. The calcium ions decreased the magnitude of the negative zeta potential and reversed the zeta potential to positive for spodumene and K-feldspar, but not for quartz, below pH 10. Calcium concentrations of 312.5 g/t enhanced the adsorption of anionic polymers onto spodumene and K-feldspar, inducing aggregation, while quartz was aggregated only above 5000 g/t. Increasing the polymer concentration increased the aggregate size for spodumene and K-feldspar, but had little effect on quartz. In situ sizing and turbidity measurements indicated the optimal conditions for spodumene aggregation were 625 g/t of calcium and 63–84 g/t of the 58% anionic-charged polyacrylamide at pH 8.5. The sedimentation results showed limited separation due to quartz entrapment in the aggregates. Anionic polyacrylamide flocculants with calcium activators can aggregate fine spodumene particles. Full article

Various forms of alumina have attracted considerable attention for their ability to remove anionic dyes from wastewater, attributed to their high specific surface area, and environmental safety. In this study, a series of modified alumina materials were synthesized for the first time using the reverse precipitation method with dual aluminum sources and without template agent to explore their applicability in various scenarios, including adsorption processes and regeneration cycles. The results revealed that non-modified alumina exhibited superior adsorption properties, while silicon-modified alumina demonstrated exceptional thermal stability during high temperature calcination. For silicon-modified alumina, the replacement of some Al–OH groups with silicon resulted in the formation of a protective silicon layer on the alumina surface, which delayed the sintering process. The pseudo-second-order kinetic model and Langmuir model were utilized to fit the experimental data. Furthermore, the adsorption and regeneration properties of silicon-modified alumina were investigated, revealing a maximum equilibrium adsorption capacity of 822.6 mg/g for Congo Red using non-modified alumina. Notably, the non-modified alumina demonstrated a 40.6% increase in its adsorption capacity compared to its initial capacity after six regeneration cycles at 1000 °C. Full article

Excess phosphorus (P) and nitrogen (N) in wastewater contribute to eutrophication, driving the need for low–cost and sustainable recovery technologies. This study presents a novel adsorbent synthesized from spent coffee grounds biochar (CB) chemically modified with Mn²⁺/Zn²⁺/Fe³⁺ (oxy)hydroxide nanoparticles (CB–M) for simultaneous removal of phosphate and ammonium. Batch adsorption experiments using both synthetic solution and municipal wastewater were conducted to evaluate the material’s adsorption performance and practical applicability. Kinetic, isotherm, thermodynamic, and sequential extraction analyses revealed that CB–M achieved maximum phosphate adsorption capacities ranging from 42.6 to 72.0 mg PO₄³⁻·g⁻¹ across temperatures of 20–33 °C, reducing effluent phosphate concentrations to below 0.01 mg·L⁻¹. Ammonium removal was moderate, with capacities ranging between 2.8 and 2.95 mg NH₄⁺·g⁻¹. Thermodynamic analysis indicated that phosphate adsorption was spontaneous and endothermic, dominated by inner–sphere complexation, while ammonium uptake occurred primarily through weaker, reversible ion exchange mechanisms. Sequential extraction showed over 70% of adsorbed phosphate was associated with Fe-Mn-Zn phases, indicating the potential for use as a slow–release fertilizer. The CB–M retained structural integrity and exhibited partial desorption, supporting its reusability for nutrient recovery. Compared to other biochars, CB–M demonstrated superior phosphate selectivity at a neutral–pH, avoided the use of hazardous metals, and transformed coffee waste into a multifunctional material for wastewater treatment and soil amendment. These findings underscore the potential of CB–M as a circular economy solution for nutrient recovery without introducing secondary contamination. Full article

Sulfation is a common strategy to enhance the acidity and modify the adsorption properties of metal–organic frameworks (MOFs), yet its impact on the coordination and accessibility of active sites remains unclear. In this study, we investigate two structurally related systems—sulfated UiO-66 (UiO-66-SO₄) and sulfated tetragonal zirconia (S-ZrO₂)—by FTIR spectroscopy with probe molecules. Isotope exchange experiments on S-ZrO₂ reveal that dehydration above 250 °C induces tridentate SO₄ coordination, while hydration leads to a reversible transition to a bidentate coordination mode. In UiO-66-SO₄, sulfates are coordinated in a bidentate fashion to Zr₆O₆ clusters, significantly affecting the accessibility of Zr sites in defective pores. This coordination prevents CO adsorption but allows acetonitrile adsorption even after room temperature activation. Unlike S-ZrO₂, due to its lower thermal stability, UiO-66-SO₄ cannot be evacuated at high temperatures and dehydration at 250 °C does not induce tridentate coordination. The presence of H-bonded hydroxyls in UiO-66-SO₄ after activation at 250 °C supports this coordination model, indicating the formation of OH-coordinated Zr sites that are inaccessible to CO but interact with stronger bases like acetonitrile. Overall, this study provides new insights into the coordination chemistry of sulfated UiO-66 and highlights that sulfation can tune acidity and adsorption in MOFs for potential catalytic and adsorption applications. Full article

Hard carbon (HC) anodes for sodium-ion batteries (SIBs) face challenges such as sluggish Na⁺ diffusion kinetics and structural instability. Herein, we propose a synergistic nitrogen-doping and defect-engineering strategy to unlock ultrahigh-rate capability and long-term cyclability in biomass-derived hard carbon. A scalable synthesis route is developed via hydrothermal carbonization of corn stalk, followed by controlled pyrolysis with urea, achieving uniform nitrogen incorporation into the carbon matrix. Comprehensive characterization reveals that nitrogen doping introduces tailored defects, expands interlayer spacing, and optimizes surface pseudocapacitance. The resultant N-doped hard carbon (NC-2) delivers a remarkable reversible capacity of 259 mAh g⁻¹ at 0.1 A g⁻¹ with 91% retention after 100 cycles. And analysis demonstrates a dual Na⁺ storage mechanism combining surface-driven pseudocapacitive adsorption (89% contribution at 1.0 mV s⁻¹) and diffusion-controlled intercalation facilitated by reduced charge transfer resistance (56.9 Ω) and enhanced ionic pathways. Notably, NC-2 exhibits exceptional rate performance (124.0 mAh g⁻¹ at 1.0 A g⁻¹) and sustains 95% capacity retention over 500 cycles at 1.0 A g⁻¹. This work establishes a universal defect-engineering paradigm for carbonaceous materials, offering fundamental insights into structure–property correlations and paving the way for sustainable, high-performance SIB anodes. Full article