Search Results (1,051)

This study presents a starch-modified calcined-ZnAl layered double-hydroxide (S-C-ZnAl-LDH) nanocomposite as a multifunctional nanofiller for poly(vinylidene fluoride) (PVDF) efficiently performing, simultaneously, ultrafiltration membrane filtration and efficient adsorbent for the recovery of Acid Blue dye-contaminated water. The synergistic effects of starch modification and thermal activation on nanofiller structure, interfacial compatibility, and membrane performance were systematically investigated through a comparison with pristine ZnAl-LDH, calcined ZnAl-LDH, starch-modified ZnAl-LDH, and calcined starch-modified ZnAl-LDH. SEM, TEM, and XRD analyses confirmed the formation of hierarchical layered nanosheet architectures with a uniform dispersion of crystalline ZnAl domains within a partially amorphous starch matrix, promoting enhanced polymer–nanofiller interfacial interactions Adsorption performance was influenced by solution pH, initial dye concentration, and temperature. Nonlinear kinetic analysis showed that the PFO model described the kinetic data better. However, the overall kinetic modeling findings suggest that Acid Blue 92 adsorption is governed by a combination of physicochemical interactions, suggesting a complex adsorption mechanism was involved. The starch-modified nanocomposite exhibited excellent regeneration stability, retaining approximately 88–90% of its adsorption capacity after five adsorption–desorption cycles. More importantly, the incorporation of S-C-ZnAl-LDH into PVDF membranes significantly enhanced membrane functionality, increasing water flux and permeance by 42.9% and 25%, respectively, while improving Acid Blue rejection by 35.7% to approximately 98%. These improvements are attributed to enhanced membrane hydrophilicity, optimized nanofiller dispersion, and favorable polymer–filler interfacial interactions that facilitate water transport while maintaining high separation efficiency. This work demonstrates an effective strategy for integrating renewable bio-based modifiers with layered nanomaterials to engineer advanced polymeric films exhibiting enhanced permeability, selectivity, durability, and reusability, providing a sustainable platform for multifunctional membrane technologies in water purification and environmental protection. Full article

Lithium recovery from salt lake brines with high Mg/Li ratios remains highly challenging due to the comparable physicochemical properties of Mg²⁺ and Li⁺, while lithium–aluminum-layered double hydroxides (Li/Al-LDHs) have emerged as promising lithium-selective adsorbents. However, their practical application is hindered by particle aggregation, limited structural stability, and insufficient processability under continuous-flow conditions. Herein, a mineral-directed synthesis strategy was developed to construct natural mineral-supported Li/Al-LDHs composite adsorbents using three abundant clay minerals, chlorite, montmorillonite, and illite, as structural substrates. The mineral crystal structures were demonstrated to regulate the nucleation, growth behavior, and dispersion of Li/Al-LDH nanosheets, resulting in distinct hierarchical architectures and lithium adsorption performances. Comprehensive structural characterization revealed the successful integration of Li/Al-LDH phases with different mineral matrices while preserving the intrinsic layered structures of both components. The results demonstrated that different mineral substrates significantly influenced the crystal growth, dispersion, and interfacial structure of Li/Al-LDHs. Among the prepared composites, montmorillonite @Li/Al-LDHs exhibited the optimal lithium adsorption performance, achieving a lithium adsorption capacity of 6.0 mg·g⁻¹ and a remarkable Li⁺/Mg²⁺ separation factor of 73.5 in a brine with a high Mg/Li ratio of 61.25. Furthermore, the optimized adsorbent maintained 81.7% of its initial adsorption capacity after 100 adsorption–desorption cycles and demonstrated stable lithium recovery performance under continuous-flow conditions. This work establishes the relationship between natural mineral crystal structures and Li/Al-LDH adsorption behaviors, providing new insights into the rational design of economical, scalable, and environmentally friendly lithium adsorbents for sustainable recovery of lithium resources from Mg-rich brines. Full article

Heterojunction construction is a key strategy for enhancing the photocatalytic efficiency of semiconductors. In this study, a composite of sulfur-doped CoAl layered double hydroxide and Fe-doped C₃N₅(S-CoAl-LDH/Fe-C₃N₅) was developed via a hydrothermal method for the synergistic oxidation-reduction degradation of the organic pollutant tetracycline (TC) and the detoxification of heavy-metal ions (Cr(VI)) in wastewater. After optimization, the CAF-4 heterojunction (the composite with 20 wt% Fe-C₃N₅ loading) exhibited TC degradation rates 5.51 and 3.97 times higher than those of pristine Fe-C₃N₅ and S-CoAl-LDH, respectively; under simulated sunlight, the Cr(VI) reduction rates were 11.75 and 4.22 times higher, respectively. The as-prepared catalyst demonstrated good stability across a wide pH range, in the presence of various cations and anions, and in different water matrices. Under coexisting pollutant conditions, the composite still achieved removal efficiencies of 82.1% for Cr(VI) and 64.7% for TC. After five cycling runs, the adsorption-photocatalytic efficiency of the composite for the removal of Cr(VI) and TC composite pollutants remained above 80%. Overall, CAF-4 shows great promise for application in the adsorption-photocatalytic treatment of wastewater containing combined Cr(VI) and TC pollution. Full article

Industrial wastewater in Islamabad has led to serious environmental and human health impacts due to the release of endocrine-disrupting chemicals (EDCs) and volatile organic compounds (VOCs) in the water bodies. The advent of wastewater treatment technologies has led to the development of novel approaches like the use of an electrocatalyst for efficient and safe removal of toxic contaminants from the wastewater. In this study, an efficient tri-metallic NiCoFe₂-LDH electrocatalyst was prepared by optimizing the metal ratios in the synthesis process using a co-precipitation method. The catalyst was characterized by various tools such as UV-visible spectroscopy, SEM, EDX, and FTIR. A three-electrode electrochemical system (counter, reference, and working electrodes) was used for electrocatalytic activity and simultaneous removal of EDCs from the wastewater. Wastewater samples were collected from selected locations along the industrial discharge channel (Nullah Lai) in the industrial zone of Islamabad city. The physio-chemical analysis showed significant water pollution, including EDCs, VOC, and heavy metals. The electrochemical treatment using NiCoFe₂-LDH demonstrated high efficiency across different scan rates (5 to 50 mV/s) and voltages (−0.02 to 1.6 V); for instance, at 1.6 V, the current density rises from 10 mA/cm² in Scan 5 to 50 mA/cm² in Scan 50. Furthermore, COD levels were significantly reduced by 74.9%, from 665.6 mg/L to 166.4 mg/L, after electrochemical treatment with NiCoFe₂-LDH. GCMS analysis of organics revealed that the electrochemical process was effective in reducing several EDC- and VOC-related peak groups. Overall, this study highlights the potential of the electrochemical approach for treating EDC-contaminated wastewater and its applicability as a sustainable solution for industrial wastewater treatment. Full article

Cadmium and arsenic accumulation during soil-covered cultivation of Morchella sextelata limits its production in contaminated soils. Two Mg/Al-layered double hydroxide–biochar (LB) composites were prepared using grinding-assisted and coprecipitation procedures and denoted as LB1 and LB2, respectively. The composites were evaluated at 2% (w/w) through a 15 d soil incubation experiment and a staged basket-cultivation experiment with three independent replicates. During incubation, LB2 significantly decreased NH₄H₂PO₄-extractable As and DTPA-extractable Cd by 28.6% and 29.1%, respectively. Sequential extraction showed that LB1 increased the operationally defined residual Cd fraction, whereas LB2 increased the oxidizable Cd fraction and produced the lowest extractable Cd and As concentrations. During cultivation, LB1 reduced total As accumulation in dry fruiting bodies by 53.9%, whereas LB2 reduced Cd accumulation by 40.0%. Amendment-induced changes in soil carbon fractions were associated with Cd and As partitioning and fruiting-body accumulation, although these correlations did not establish causality. The two as-prepared composites therefore produced distinct metal-specific responses under the tested conditions. Full article

Chloride ingress is a critical durability concern for cement-based construction materials exposed to marine environments and other chloride-containing conditions, as it can accelerate material degradation and reduce service life. To improve the chloride ingress resistance of mortar containing pre-wetted porous fine aggregate, the effects of internal curing provided by the porous fine aggregate and ion adsorption by calcined layered double hydroxides (CLDHs) on mortar performance were investigated. Compressive strength, pore structure, water-soluble chloride profiles, X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS) were employed to analyze chloride transport and fixation in mortars with different porous fine aggregate replacement ratios and CLDHs contents. The results showed that the pre-wetted porous fine aggregate was beneficial to later-age strength development, which may be associated with its internal water storage and release characteristics, although its effect varied with the replacement ratio. At a replacement ratio of 10%, the pore structure of the mortar remained relatively stable, and the increase in water-soluble chloride content relative to the reference mortar was mainly confined to the near-surface region. By contrast, higher replacement ratios increased the total porosity and the proportions of larger pores and pore throats, thereby promoting chloride migration into the intermediate and deeper regions. CLDHs did not significantly improve the overall pore structure of the mortar, but may have reduced the water-soluble chloride content through structural reconstruction and interlayer fixation. Among the investigated mixtures, the mortar containing 3% CLDHs exhibited the lowest water-soluble chloride content at all tested depths. The pre-wetted porous fine aggregate primarily regulated the pore structure and chloride transport conditions, whereas CLDHs mainly reduced water-soluble chloride content and may contribute to chloride binding. Their combined contributions helped retard chloride migration into the mortar and improve its resistance to chloride ingress. Full article

Chloride-induced steel corrosion is one of the major causes of durability degradation in reinforced concrete (RC) structures. Conventional inhibitors have inherent drawbacks in environmental safety, long-term stability, and cement compatibility. Plant extracts, featuring renewability, biodegradability, and abundant bioactive components, have emerged as promising green corrosion inhibitors. This review summarizes the categories, inhibition mechanisms, and evaluation methods of plant-based inhibitors, and discusses multi-scale characterization and computational techniques for mechanism research. A conceptual Ginkgo biloba extract (EGb)-LDH strategy is discussed as a possible future route for plant-based inhibitor delivery, but its chloride-responsive release and corrosion-protection performance remain to be experimentally verified. Full article

Nickel–iron layered double hydroxides (NiFe-LDHs) are among the most active earth-abundant electrocatalysts for the oxygen evolution reaction (OER) in alkaline media, yet their performance remains sensitive to structure, electrolyte history, and testing practice. Unlike general summaries of NiFe-LDH synthesis and activity, this review emphasizes the dynamic nature of NiFe-LDHs as precatalysts, focusing on interlayer chemistry, electrolyte history, anodic reconstruction, mechanistic interpretation, and benchmarking reliability. It highlights the activation of NiFe-LDHs under anodic conditions into γ-NiFeOOH-like Ni–Fe oxyhydroxides, where Fe sites embedded in the NiOOH matrix and coupled Ni–Fe motifs jointly govern the catalytic activity. The discussion focuses on the role of layer charge, interlayer anions, layer spacing, and ion/water transport in reconstruction and catalytic activity. Catalyst crystallinity, orientation and loading are also related to common synthesis methods such as coprecipitation, hydrothermal growth and electrodeposition. Moreover, the main performance improvement strategies including defect engineering, heteroatom doping, conductive supports, and interlayer modification are discussed in relation to the adsorption of key OER intermediates. Finally, practical guidelines for reliable benchmarking are discussed, as well as the remaining challenges for the development of stable and efficient NiFe-LDH catalysts for alkaline electrolyzers. Full article

Developing efficient and durable oxygen evolution reaction (OER) electrocatalysts is critical for industrial alkaline water electrolysis. Here, we fabricated a Mo–V co-doped NiFe layered double hydroxide (NiFeMoV-LDH) electrode on nickel foam to modulate its intrinsic activity and structural stability. Physical and electrochemical evidence indicates that the synergistic incorporation of Mo and V increases the active surface area and accelerates charge-transfer kinetics. XPS analysis indicates higher average static valence states of the Ni and Fe centers, driven by interfacial electronic redistribution. Consequently, the optimized NiFeMoV-LDH electrode delivers low overpotentials of only 260 mV and 291 mV at 100 and 300 mA·cm⁻², respectively, with a small Tafel slope of 30.64 mV·dec⁻¹ in 1.0 M KOH. Notably, the electrode demonstrates stable durability for over 350 h at a high current density of 500 mA·cm⁻². In situ Raman analysis reveals that the Mo–V synergistic modulation delays the dynamic phase-transition threshold to the active NiOOH phase to 1.43 V, effectively mitigating premature over-oxidation and protecting the host matrix from structural degradation under continuous OER extremes. These insights underscore the efficacy of polymetallic synergistic regulation for designing industrially relevant OER electrodes. Full article

Uranium separation from aqueous media remains a critical challenge at the intersection of nuclear fuel cycle efficiency and environmental safety. Layered double hydroxides (LDHs) are promising adsorbents for U(VI) removal and serve as versatile inorganic matrices for the design of nanocomposite sorbents. However, the influence of their key structural parameter, Me²⁺/Me³⁺ cationic ratio, on sorption performance and composite functionality remains insufficiently explored. This study investigates how the Zn^2+/Al³⁺ ratio governs the structure, sorption kinetics, and U(VI) uptake mechanisms of Zn-Al LDH. Characterization by XRD, TEM, XPS, XAFS, cryogenic laser-induced fluorescence spectroscopy, Raman, and positron annihilation spectroscopy revealed that increasing Al³⁺ content up to the optimal ratio of 2/1 enhances sorption capacity through increased positive charge density, reaching maximum static (47.2 mg/g) and dynamic (17.05 mg/g) capacities. EXAFS and fluorescence spectroscopy demonstrate that U(VI) adsorption at pH 4.0 proceeds via inner-sphere complexation involving mononuclear uranyl carbonate/hydroxyl species (UO₂(CO₃)₂²⁻, UO₂(CO₃)₃⁴⁻, UO₂(OH)_n⁽²⁻ⁿ⁾) and polynuclear complexes, predominantly (UO₂)₂(CO₃)(OH)₃⁻. Further increase to Zn/Al = 1/1 induced mesopore narrowing and inhibited diffusion, drastically decreasing dynamic performance. These findings establish the Zn/Al ratio as a key parameter governing LDH sorption efficiency and provide a mechanistic basis for the rational design of LDH-based composite sorbents. Full article

Polysaccharide-based organic-inorganic hybrid carriers combine renewable polymer matrices with inorganic phases that can modify mechanical integrity, swelling, barrier performance, payload retention, and release behavior. This review critically evaluates alginate as a reference matrix together with chitosan, cellulose/nanocellulose, starch/maltodextrin, pectin, carrageenan, and related polysaccharides, focusing on how matrix chemistry, inorganic-phase properties, interfacial interactions, and fabrication route govern encapsulation efficiency, loading, structural stability, swelling, mechanical and barrier properties, storage retention, and release kinetics. Silica and mesoporous silica, clays and halloysite, layered double hydroxides (LDHs), metal oxides, hydroxyapatite, magnetic particles, and metal-organic frameworks are compared according to their reservoir, reinforcing, diffusion-controlling, responsive, and safety-related functions. Representative quantitative findings illustrate the importance of hybrid architecture; for example, incorporation of LDHs into an alginate matrix reduced erythropoietin release after 108 h from 86% to 24% while increasing mechanical performance by approximately 5–30-fold. In this review, particular attention is given to volatile and bioactive compounds, for which storage retention, oxidation stability, headspace behavior, and application-relevant release are as important as initial encapsulation efficiency. Key challenges, such as long-term stability, standardization of release studies, scalability, safety assessment, and performance in real formulations, are also discussed, together with future directions for sustainable, application-specific hybrid carrier systems. Overall, the review provides a structure-property-application framework for selecting matrix-filler-processing combinations for controlled-release systems. Full article

The transformation of toluene to benzaldehyde via green and sustainable routes is of great significance in the fine chemical industry. However, hard activation of benzylic C(sp³)-H bonds and facile overoxidation of the generated benzaldehyde collectively render the selective oxidation of toluene extremely challenging. In this study, we constructed a core–shell heterostructure photocatalyst, CeO₂@NiFe-LDH, employing molecular oxygen as the oxidant. Under mild conditions of room temperature and visible-light illumination, the catalyst achieves a toluene conversion rate of 1.936 mmol·g⁻¹·h⁻¹ with an excellent benzaldehyde selectivity of 81.0%, and its catalytic performance is significantly superior to that of the individual single-phase materials and the simple physical mixture. Optical and electrochemical measurements confirm enhanced visible-light absorption and utilization, as well as greatly improved separation and migration efficiency of photogenerated charge carriers. Furthermore, the CeO₂@NiFe-LDH heterostructure features staggered band alignment, promoting S-scheme charge transfer across the heterointerface, thereby substantially boosting the redox capacity of the composite catalyst. Consequently, the photogenerated carriers with high reactivity are fully engaged in catalytic reactions, enabling efficient carrier utilization and ultimately leading to a significantly enhanced photocatalytic performance. This study not only demonstrates the outstanding application potential of CeO₂@NiFe-LDH for the visible-light-driven selective oxidation of toluene to benzaldehyde, but also offers a novel strategy for enhancing the photocatalytic performance of LDH-based materials. Full article

Biodiesel production from waste cooking oils, non-edible oils and other low-grade lipid feedstocks is constrained by free fatty acids, water, salts, oxidation products, and the poor miscibility of triglycerides with short-chain alcohols. Carbon–inorganic hybrid catalysts are attractive because the inorganic phase can provide strong acid or base sites, while the carbon phase can alter dispersion, wettability, pore accessibility, microenvironment polarity, leaching, and recovery. Yet the term hybrid is often applied to materials for which the carbon component has not been shown to affect catalysis. This critical review therefore focuses on one defined reaction scenario: esterification and transesterification for biodiesel production from low-grade lipid feedstocks. The discussion is organized by the catalytic problem rather than by an unrestricted catalogue of materials. Carbon-supported CaO and MgO, carbon-coupled layered-double-hydroxide-derived mixed oxides, sulfonated carbon–inorganic acids, bifunctional acid–base systems, magnetically recoverable ferrite/carbon catalysts, and graphenic supports are compared through structure–activity relationships, reaction conditions, feedstock quality, FAME yield, heterogeneity, reusability, and post-reaction evidence. Particular attention is given to the distinction between a true interfacial effect and activity caused by leached Ca, K, Na or sulfonic species. A minimum evidence hierarchy is proposed, requiring carbon-only, inorganic-only, and physical-mixture controls, hot-filtration tests, elemental analysis of the liquid phase, recovered-mass accounting, and post-reaction structural characterization. The literature shows that high first-cycle yield is common, whereas water tolerance, low leaching, retained active-site density, and continuous operation remain uncommon. The most defensible future direction is therefore not greater compositional complexity, but simpler hybrid architectures designed around a specific failure mode and validated under realistic feedstock and reactor conditions. Full article

The increasing accumulation of pharmaceutical residues in water environments poses serious threats concerning environmental safety and public health, mainly due to their tenacity, continuous bio-activity, and resistance to traditional wastewater treatment processing. Although many nano-bio/chemosensor systems have been reported for the monitoring and removal of pharmaceutical residues, the literature remains fragmented regarding their ability to integrate detection and remediation into a single platform. In this context, this review critically examines recent developments in nano-bio/chemosensor platforms for simultaneous detection and elimination of pharmaceutical effluents in wastewaters. Particular emphasis is placed on their functional integration, detection mechanisms, analytical performance, and removal pathways. This review covers the major pharmaceutical categories, including pharmaceutical drugs, antibiotics, hormones, perfluorinated compounds, and drugs of abuse and discusses nanostructured platforms based on metal organic frameworks (MOFs), nanochannel-based immunosensors, noble metal nanoparticles, layered double hydroxides, and hybrid composites. Detection approaches based on fluorescence modulation, electrochemical impedance, ionic current rectification, surface-enhanced Raman scattering (SERS), and colorimetric nanoenzyme activity could lead to extremely low detection limits. In addition, removal mechanisms such as adsorption, photocatalysis, advanced Fenton-induced oxidation processes, and nanoenzymes allow for high degradation efficiencies (>80–99%). Significant advantages for real-time monitoring and sustainable wastewater treatment can be achieved by multifunctional nanoplatforms that integrate detection and remediation capabilities. Finally, this review identifies current limitations and research gaps regarding practical application, matrix effects, regeneration, stability, scalability, and integration into real wastewater treatment systems and outlines future research directions towards more efficient and environmentally relevant multifunctional platforms. Full article

A flexible integrated composite electrode is fabricated using NiV-layered double hydroxide (NiV-LDH) nanosheets grown perpendicularly onto a Ti₃C₂T_x MXene-incorporated carbon nanofiber scaffold (MXene/CNFs). This hybrid structure, prepared by electrospinning and a hydrothermal treatment, is referred to as NiV-LDH@MXene/CNFs. Constructed from a conductive MXene/CNF scaffold and vertically aligned NiV-LDH nanosheets, the integrated flexible electrode offers uninterrupted electron transport, good flexibility, abundant active sites, and strong interfacial cohesion, thereby obviating the use of polymeric binders and conductive additives. The hydrophilic nature of MXene and the three-dimensionally interconnected porous structure favor rapid electrolyte uptake and ion diffusion. As a result of these synergistic effects, the composite exhibits a specific capacitance of 614 F g⁻¹ at 1 A g⁻¹ and retains 60% of its initial capacitance after 10,000 cycles at 5 A g⁻¹ in a three-electrode cell. An asymmetric supercapacitor made of this material and activated carbon achieves 68.75% capacitance retention under the same cycling protocol at 5 A g⁻¹ and shows a stable open-circuit voltage of 1.37 V. Two cells in series are capable of lighting a 3 V LED strip. Overall, this work validates an effective strategy to prepare high-capacity, robust, and binder-free flexible electrodes for advanced energy-storage applications. Full article