Search Results (133)

Reversible emulsion drilling fluids integrate the advantages of water-based and oil-based systems, offering solutions to critical challenges in shale oil and gas development. However, conventional reversible emulsions face limitations including poor stability, high cost, and material scarcity. This research introduces widely available, eco-friendly modified nanocrystalline cellulose (MNCC) as a sustainable alternative. While current reversible drilling fluids primarily depend on organoclays and adopt aqueous phases containing 20–25% CaCl₂ for shale inhibition, pH-responsive MNCC was validated as an effective reversible emulsifier capable of stabilizing emulsions through 48 consecutive phase-inversion cycles. Enhanced emulsion stability was achieved with organoclay at an optimal dosage (≤2.5 g/100 mL), and a composite interfacial film superior to the film formed by pure MNCC was fabricated via the combination of organoclay and MNCC. Increasing the organoclay content elevated the acid requirements for phase inversion (due to its lipophilicity) but reduced the alkali needs. Finally, higher CaCl₂ concentrations in the aqueous phase reduced the acid demand for inversion yet increased alkali consumption and diminished stability in both oil-in-water (O/W) and water-in-oil (W/O) emulsions. These effects are attributed to the dual role of CaCl₂ in compressing the electrical double layer and modifying phase density differences, synergistically governing reversible inversion behavior. This research provides a foundation for applying nanocrystalline cellulose-stabilized reversible emulsion drilling fluids, offering practical solutions for efficient development of sensitive reservoirs like shale. Full article

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

This review provides a comprehensive analysis of organically grafted clay minerals modified with organo-alkoxides, silanes, and amine-based compounds for water treatment applications. Emphasis is placed on per- and polyfluoroalkyl substances (PFAS) as representative emerging contaminants due to their persistence and environmental relevance. The review systematically examines synthesis strategies, surface functionalization mechanisms, and structure–performance relationships governing adsorption behavior. The analysis demonstrates that adsorption performance is controlled by the interplay between grafting chemistry, surface accessibility, and environmental conditions rather than adsorption capacity alone. While ion-exchange organoclays exhibit high adsorption capacities under controlled conditions, covalently grafted and polymer-modified systems provide superior stability and resistance to leaching. However, discrepancies in experimental conditions across studies limit direct comparison of reported adsorption capacities. The review identifies key challenges related to regeneration efficiency, environmental safety, and scalability, and highlights that long-term stability and compatibility with realistic water matrices are decisive factors for practical implementation. Future research should focus on standardized testing protocols, pilot-scale validation, and comprehensive environmental risk assessment. Full article

This paper presents the results of a laboratory-based treatability study conducted for a confidential former wood treating site heavily impacted by a creosote non-aqueous-phase liquid (NAPL) containing pentachlorophenol (PCP). PCP impacts in the silty sands extended to approximately 33 ft (10 m) below the ground surface (bgs), with discrete soil samples containing PCP concentrations up to 14,500 mg/kg, and groundwater PCP concentrations forming a main plume exceeding 1 mg/L over 2.16 acres (0.87 ha). Treatability testing was performed on unspiked and NAPL-spiked site soils with total PCP concentrations ranging from 10 to 100 mg/kg, respectively, and leachable PCP concentrations of approximately 3 to 8 mg/L. Stabilization/solidification (S/S) mix designs using 5 to 10 weight percent (wt%, dry-reagent-to-wet-soil mass basis) of a Portland cement (PC) blend and 1 wt% powdered bentonite met the minimum unconfined compressive strength (UCS) and maximum hydraulic conductivity (K) performance criteria of 50 lb/in2 (345 kPa) and 1 × 10⁻⁶ cm/s, respectively, within the specified 28-day cure time. Long-term semi-dynamic leach testing was performed on S/S-treated soils using a modified United States Environmental Protection Agency (EPA) Method 1315 test incorporating a polydimethylsiloxane (PDMS) liner to improve the data reliability for hydrocarbons. Results showed that adding 1 wt% organoclay (OC) to the S/S mix designs did not substantially reduce leaching of common semi-volatile organic compounds (SVOCs) such as naphthalene, acenaphthene, phenanthrene and benzo(a)anthracene compared to mixes using only the PC blend with bentonite, consistent with previous studies. However, the inclusion of OC had a decisive effect on PCP immobilization, providing an order-of-magnitude (10×) reduction in the cumulative mass release of PCP over the test duration. This benefit diminished with decreasing degree of chlorination for other phenolic compounds. Full article

The widespread occurrence of emerging mycotoxins (EMs) produced by Fusarium, Aspergillus, and Penicillium species has raised increasing concerns regarding food and feed safety. Mitigation strategies currently applied to control regulated mycotoxins in feed may also be effective in reducing contamination by EMs. This study comparatively evaluated the in vitro adsorption efficacy of two leonardites, eight natural smectites, and two modified clays (organoclays) against EMs produced by Fusarium, Aspergillus, and Penicillium spp. All materials were tested at two inclusion levels (0.1 and 0.5% w/v) under two pH conditions (pH 3 and 7), simulating the gastrointestinal environment of monogastric animals. Adsorption performance was strongly influenced by mycotoxin chemistry, adsorbent type, inclusion rate, and medium pH. Organoclays exhibited the highest and most consistent efficacy, achieving near-complete adsorption of beauvericin (BEA) and enniatins (ENNs) (>98–100%) at 0.1% (w/v), as well as high removal of mycophenolic acid (MYC. A.) and citrinin (CIT) (>90%) across both pH conditions. Natural smectites showed high but more selective adsorption, removing >90% of BEA and ENNs at low inclusion rates, while displaying limited efficacy toward fusaric acid (FA) and patulin (PAT). Leonardites demonstrated intermediate and material-dependent performance; leonardite L1 adsorbed approximately 90% of BEA at 0.1% (w/v), whereas ENN adsorption ranged from ~36% to 80% at the same inclusion rate and exceeded 90% only at higher dosages. None of the tested materials effectively adsorbed patulin (PAT) at pH 7; however, at pH 3, four smectites exhibited partial adsorption, and one trioctahedral smectite achieved more than 90% PAT adsorption under acidic conditions. Overall, organoclays displayed the broadest adsorption spectrum across structurally diverse mycotoxins, while smectites exhibited high selectivity driven by surface charge density and interlayer interactions. Leonardite-based materials showed moderate but highly variable adsorption performance, likely influenced by heterogeneity in humic functional groups and physicochemical properties. These findings highlight the need for tailored adsorbent selection or combined mitigation strategies to achieve effective mycotoxin control in the animal feed industry. Full article

This study investigated the characterization and application of organoclay formulations in a chemoautotrophic biofloc system. Organoclays were produced using the calcination method and bentonite, chitosan, corn, and tapioca starches as ingredients. Thermogravimetric analysis confirmed the high thermal stability of bentonite, whereas biopolymers (tapioca, chitosan, and corn starch) exhibited greater thermal sensitivity and a lower residual mass. Scanning electron microscopy revealed that organoclays had increased porosity (4–21 µm) compared to bentonite, while energy-dispersive spectroscopy confirmed the retention of key chemical elements. X-ray diffraction and Fourier-transform infrared spectroscopy indicated structural modifications due to thermal processing. In aqueous conditions, bentonite and organoclays disaggregated into particles with sizes between 0.76 and 1.24 μm. Based on these physicochemical properties, three formulations were selected for nitrification trials due to their stability in water, O1 (bentonite + tapioca), O2 (bentonite + tapioca + chitosan), and O6 (bentonite + corn starch), along with a 100% bentonite treatment and a control group (C) supplemented with inorganic salts and artificial Needlona^® substrates. All treatments achieved full nitrification within 37 days, with O1 exhibiting the best performance by maintaining ammonia and nitrite levels within safe thresholds. These findings suggest that organoclays, particularly O1, can enhance nitrification stability, providing a promising strategy for water quality management in intensive aquaculture systems. Full article

With the rapid expansion in the use of nanomaterials, ensuring their reprocessability has become a critical consideration for the sustainable development of polymer-based nanocomposites. In this study, the effects of repetitive thermo-mechanical processing cycles on the properties of polycarbonate (PC)/organoclay nanocomposites, as well as the impact of reactive extrusion of reprocessed PC/organoclay nanocomposites using a chain extender, were investigated for the first time. The nanocomposites were processed three times using a twin-screw extruder, and a multi-anhydride functional chain extender was incorporated to counteract the thermo-mechanical degradation observed after the third extrusion cycle. Morphological analysis indicated that the delamination of clay nanolayers within the polymer matrix was slightly enhanced with increasing extrusion cycles, while the addition of the chain extender further promoted nanoclay exfoliation. Despite the improved clay dispersion in PC, both rheological and tensile measurements revealed the detrimental effects of repeated reprocessing on the nanocomposites. The chain extender effectively mitigated this degradation by relinking cleaved polymer chains; consequently, the complex viscosity and storage modulus at 0.1 Hz of the three-times-extruded nanocomposite increased by 248% and 426%, respectively, following chain extender incorporation. The effectiveness of the chain extender was further evidenced by a 27% enhancement in tensile strength. The glass transition temperatures of the samples were not significantly affected by either the extrusion cycles or the addition of the chain extender. The thermal stability of the nanocomposites decreased with increasing numbers of extrusion cycles; however, the incorporation of the chain extender imparted enhanced resistance to thermal degradation, as confirmed by thermogravimetric analysis. Full article

Bentonite is the most widely used raw material for producing organoclays, which have numerous industrial and environmental applications. Due to their hydrophobicity, high swelling, and strong affinity for organic compounds, organoclays are effective in removing organic solvents from contaminated water originating from pipeline leaks, oil spills, traffic accidents, and industrial discharges. Such contamination not only degrades water quality but also forms surface films that hinder oxygen transfer, threatening aquatic ecosystems. In this study, two sodium bentonites with different specific surface areas (30 and 50 m²/g) were modified with three quaternary ammonium salts of varying molar masses and alkyl chain lengths (Sun, Arq, and Arm) to evaluate their performance in organic solvent sorption (gasoline, diesel, and kerosene). The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), and swelling capacity and sorption efficiency. The swelling capacity was determined according to ASTM D5890-19 (Foster method) using gasoline, diesel, kerosene, toluene, and xylene, while the sorption efficiency was assessed following ASTM F726-17 in gasoline, diesel, and kerosene, chosen due to their high potential for water contamination and frequent occurrence in oil spill and leakage scenarios. These solvents also differ in polarity and aromatic content, providing a relevant model for hydrocarbon mixtures commonly found in the environment. Results showed that the interaction between the clay and the surfactant depended strongly on the modifier’s chemical structure. The sorption capacity increased with greater interlayer expansion, surfactant molar mass, and specific surface area of the clay. Among all samples, the Arm-modified natural bentonite (VLArm) exhibited the best performance, with adsorption capacities of up to 6 g/g for diesel, 5 g/g for gasoline, and 5 g/g for kerosene. These values exceeded most previously reported organoclays. These findings demonstrate that optimizing the combination of clay properties and surfactant chemistry can yield highly efficient, low-cost organoclays for environmental remediation of organic contaminants. Full article

Natural and modified clay minerals are widely used in environmental technologies to remove a wide range of toxic substances from aquatic and soil ecosystems. This study assessed the toxicity of synthesized organoclays compared to pure bentonite using microbiological, phytotoxic, and instrumental (biosensor) methods. Organoclay containing lauramine oxide (a non-ionic surfactant) was found to have an increased toxic effect on all test organisms analyzed. Based on the phytotesting parameters, radish was found to be the most sensitive test organism in these experiments, as it was significantly affected by toxic substances, demonstrating noticeable changes in its morphology and morphometry. Minimal toxicity was demonstrated for organoclay containing alkyl polyglucoside (a non-ionic surfactant), which was used in all tests. Furthermore, organoclay containing disodium cocoamphodiacetate (an amphoteric surfactant) also exhibited minimal toxicity in phytotesting, including germination assessment (radish) and evaluation of morphometric characteristics using a biosensor method. The study confirms that the type of organic modifier significantly impacts the biocompatibility of organoclays. Using fewer toxic surfactants can improve the environmental acceptability of these materials for use in cleaning up contaminated ecosystems. Full article

Background: Although teriparatide is efficacious, its once-daily subcutaneous injections cause local adverse events, inconvenience, and higher cost, limiting long-term adherence. Therefore, this research aims to engineer a pH-responsive oral formulation of teriparatide for osteoporosis therapy. Methods: A layered silicate nanocomplex was obtained by spontaneous self-assembly of teriparatide (Teri) with 3-aminopropyl magnesium phyllosilicate (AC). The nanocomplex (AC-Teri) was then coated with a 1:1 blend of two polymethacrylic acid derivatives (Eudragit^® L100 and Eudragit^® S 100) to provide pH-triggered drug release along the gastrointestinal tract. Results: AC-Teri and the coated nanocomplex (EE/AC-Teri) displayed high encapsulation efficiency (>90%) with narrow size distributions. In a stepwise buffer transition system, EE/AC-Teri demonstrated pH-dependent release, with less than 25% drug liberated at pH 1.2, approximately 54% at pH 6.8, and 74% at pH 7.4 over 24 h. Particle size and ζ-potential of EE/AC-Teri shifted in parallel with dissolution of the outer polymer shell. EE/AC-Teri also protected the peptide against enzymatic degradation, preserving the secondary structure of encapsulated teriparatide in simulated intestinal fluids. Compared with free drug, EE/AC-Teri enhanced transcellular drug permeation 2.7-fold in Caco-2 cells. In dexamethasone-induced osteoporotic rats, oral EE/AC-Teri significantly stimulated bone formation while suppressing resorption; micro-CT and histology confirmed recovery of trabecular architecture. Conclusions: EE/AC-Teri represents a promising oral teriparatide formulation for the effective management of osteoporosis. Full article

The microparticle-enhanced microfiltration is a technique that combines the use of microparticulate adsorbent material dispersed in aqueous solution and microfiltration membranes for the removal of ions and emerging contaminants with low energy consumption. Thus, the objective of this work was to synthesize an organoclay, BAPTES, based on bentonite and (3-aminopropyl)triethoxysilane for use as a semi-synthetic adsorbent material in the microparticle-enhanced microfiltration process for the removal of AR27 in aqueous systems. For this purpose, the obtained organoclay was structurally characterized by FTIR-ATR-FEDS, SEM-EDS, DLS, and thermal analysis. In addition, equilibrium adsorption and kinetic studies of AR27 were performed. The results showed a significant increase in the adsorption capacity of AR27 by organoclay (86.06%) compared to natural bentonite (2.10%), due to the presence of ionizable amino groups in the organoclay structure that promote electrostatic interactions with the dye. Furthermore, kinetic studies showed that the adsorption process follows a pseudo-first-order model and that the equilibrium data better fits the Temkin model, indicating a heterogeneous adsorption surface with different binding energies. The evaluation of enhanced microfiltration with BAPTES microparticles showed that the adsorption capacity obtained in continuous flow experiments (14.25–33.63 mg g⁻¹) was lower than that determined experimentally under equilibrium conditions (~39.5 mg g⁻¹), suggesting that the residence time of the analyte and the adsorbent in the filtration cell is a determining factor in the retention values obtained. In addition, desorption studies revealed that basic pH had a greater effect than the presence of salts and the use of ethanol, favoring the weakening of the AR27-BAPTES interaction. Finally, the results highlight the potential use of BAPTES microparticle-enhanced microfiltration in applications involving the treatment of contaminated industrial effluents. Full article

Water pollution by organic dyes poses serious environmental and health challenges, demanding efficient and selective remediation methods. In this study, we engineered tailored organo-clay nanocomposites by modifying montmorillonite with hexadecyltrimethylammonium bromide (HTAB) and intercalating polyethylene glycol (PEG) chains of two distinct molecular weights (PEG200 and PEG4000). Comprehensive characterization techniques (XRD, FTIR, SEM, zeta potential, and TGA) confirmed the successful modification of the composites. Notably, PEG4000 promoted significant interlayer expansion, as evidenced by the shift of the (00l) reflection corresponding to the basal spacing d, indicating an increase in basal spacing. This expansion contributed to the formation of a well-ordered porous framework with uniformly distributed pores. In contrast, PEG200 produced smaller pores with a more uniform distribution but induced less pronounced interlayer expansion. Adsorption tests demonstrated rapid kinetics, achieving equilibrium in under 15 min, and impressive capacities: 420 mg/g of methylene blue (MB) adsorbed on PEG200/MMT@HTAB, and 385 mg/g of Congo red (CR) on PEG4000/MMT@HTAB. The crucial role of PEG chain length in adsorption selectivity was assessed, showing that shorter PEG chains favored methylene blue adsorption by producing narrower pores and faster kinetics, while longer PEG chains enhanced CR uptake via a stable, interconnected pore network that facilitates diffusion of larger dye molecules. Thermodynamic and Dubinin–Radushkevich analyses confirmed that the adsorption was spontaneous, exothermic, and predominantly driven by physical adsorption mechanisms involving weak van der Waals and dipole interactions. These findings highlight the potential of PEG-modified montmorillonite nanocomposites as cost-effective, efficient, and tunable adsorbents for rapid and selective removal of organic dyes in wastewater treatment. Full article

The ice sheet and subglacial geological environment in Antarctica have become the focus of scientific exploration. The development of Antarctic drilling technology will serve as a crucial safeguard for scientific exploration. However, the extremely ultra-low temperatures and intricate geological conditions present substantial obstacles for drilling operations in Antarctica, and the existing drilling fluid technology cannot satisfy the requirements of efficient and safe drilling. To ameliorate the wettability and rheology of ultra-low-temperature drilling fluids, a new amide material (HAS) was prepared using dodecylamine polyoxyethylene ether, azelaic acid, and N-ethylethylenediamine as raw materials. Experiments using infrared spectroscopy, nuclear magnetic hydrogen spectroscopy, and contact angle indicated that the target product was successfully synthesized. Performance evaluation showed that 2% HAS could achieve a yield point of 2.5 Pa for drilling fluid at −55 °C, and it also gave the fluid superior shear-thinning characteristics and a large thixotropic loop area. This indicated that HAS significantly enhanced the rheological properties of the drilling fluid, ensuring that it can carry cuttings and ice debris. In addition, 2% HAS could also increase the colloidal rate from 8% to more than 76% at −55 °C in different base oils. Meanwhile, the colloid rate was maintained above 92.4% when the density was 0.92~0.95 g/cm³. Mechanism studies showed that HAS increased the zeta potential and decreased the particle size of organoclay. At the same time, it changed the organoclay state from a clustered state to a uniformly dispersed state, and the particle size decreased. It was found that HAS formed a weak gel grid structure through interactions between polar groups, such as amide and imino groups with organoclays particles, thus improving the rheology and wettability of drilling fluid. In addition, HAS is an environmentally friendly high-performance material. Full article

This work investigates the effect of nanoclay addition—specifically natural montmorillonite (MMT) and organo-modified montmorillonite (O-MMT)—on the elastocaloric performance of natural rubber (NR), a promising material for solid-state cooling due to its non-toxicity, low cost, and ability to exhibit large adiabatic temperature changes under moderate stress (~a few MPa). Despite these advantages, the cooling efficiency of NR remains lower than that of conventional vapor-compression systems. Therefore, improving the cooling capacity of NR is essential for the development of solid-state cooling technologies competitive with existing ones. To address this, two series of NR-based nanocomposites, containing 1, 3, and 5 phr nanofiller, were prepared by melt compounding and hot pressing and characterized in terms of morphology, thermal, mechanical, and elastocaloric properties. The results highlighted that the better dispersion of the organoclays within the rubber matrix promoted not only a better mechanical behavior (in terms of stiffness and strength), but also a significantly enhanced cooling performance compared to MMT nanofilled systems. Moreover, NR/O-MMT samples demonstrated up to a ~45% increase in heat extracted per refrigeration cycle compared to the unfilled NR, with a coefficient of performance (COP) up to 3, approaching the COP of conventional vapor-compression systems, typically ranging between 3 and 6. The heat extracted per refrigeration cycle of NR/O-MMT systems resulted in approx. 16 J/cm³, higher with respect to the values reported in the literature for NR-based systems (ranging between 5 and 12 J/cm³). These findings emphasize the potential of organoclays in enhancing the refrigeration potential of NR for novel state cooling applications. Full article

This study investigates the hydrogen permeability of injection-molded polyamide 6 (PA6) nanocomposites reinforced with organo-modified montmorillonite (OMMT) at varying concentrations (1, 2.5, 5, and 10 wt. %) for potential use as Type IV composite-overwrapped pressure vessel (COPV) liners. While previous work examined their mechanical properties, this study focuses on their crystallinity, morphology, and gas barrier performance. The precise inorganic content was determined using thermal gravimetry analysis (TGA), while differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and scanning electron microscopy (SEM) were used to characterize the structural and morphological changes induced by varying filler content. The results showed that generally higher OMMT concentrations promoted γ-phase formation but also led to increased agglomeration and reduced crystallinity. The PA6/OMMT-1 wt. % sample stood out with higher crystallinity, well-dispersed clay, and low hydrogen permeability. In contrast, the PA6/OMMT-2.5 and -5 wt. % samples showed increased permeability, which corresponded to WAXD and SEM evidence of agglomeration and DSC results indicating a lower degree of crystallinity. PA6/OMMT-10 wt. % showed the most-reduced hydrogen permeability compared to all other samples. This improvement, however, is attributed to a tortuous path effect created by the high filler loading rather than optimal crystallinity or dispersion. SEM images revealed significant OMMT agglomeration, and DSC analysis confirmed reduced crystallinity, indicating that despite the excellent barrier performance, the compromised microstructure may negatively impact mechanical reliability, showing PA6/OMMT-1 wt. % to be the most balanced candidate combining both mechanical integrity and hydrogen impermeability for Type IV COPV liners. Full article