Investigations on organo-montmorillonites modified by binary nonionic/zwitterionic surfactant mixtures for simultaneous adsorption of aflatoxin B1 and zearalenone

Novel MoS2/montmorillonite hybrid aerogel encapsulated PEG as composite phase change materials with superior solar-thermal energy harvesting and storage

Phase change materials (PCMs) offer significant advantages in energy conversion and storage by facilitating the storage and release of thermal energy during phase transition processes. However, challenges such as leakage during PCM phase transitions and poor light absorption properties have constrained their application in the field of photothermal energy storage. In this study, Montmorillonite (Mt) and molybdenum disulfide (MoS2) has been used to design and synthesize hybrid aerogels (MoS2/Mt) boasting high mechanical strength and excellent photothermal conversion performance. These aerogels are then used to encapsulate polyethylene glycol (PEG) to prepare composite PCMs with outstanding solar-thermal conversion and storage performances. The results show that the synthesized MoS2/Mt-PEG composite PCMs exhibit high enthalpies of melting and solidification of 169.16 J/g and 170.78 J/g, respectively, while the aerogel supporting material has a high compressive modulus of 1.96 MPa. Moreover, the composite material displayed excellent thermal stability and leakage resistance after undergoing 30 melting-cooling cycles. Furthermore, the incorporation of MoS2 imparted outstanding light absorption properties to the MoS2/Mt-PEG composite, resulting in a high light absorption and photothermal conversion-storage efficiency of 93.4 % and 96.47 %, respectively. Synthesized composite PCMs also demonstrate outstanding performance in solar-thermal-electricity conversion, achieving a voltage output of 458 mV under illumination conditions and maintaining a sustainable voltage output even after removing the light source. Thus, the composite PCMs prepared in this work can meet the requirements of high enthalpy, effective leakage prevention, efficient solar-thermal conversion and solar-thermal-electricity conversion performance, thereby presenting potential applications in practical solar energy collection, conversion, and storage.

Tunable Colloidal Properties of Lauramidopropyl Betaine and Li Co-modified Montmorillonite in Ethanol/Water

Montmorillonite (Mt) is a hydrophilic clay mineral with a generally high cationic exchange capacity and a remarkable swellability in water. Yet the application of Mt in cosmetics, paints, polymer nanocomposites, drug delivery systems, and tissue engineering are limited due to its unfavorable swelling and dispersion in alcohol/water mixtures. Improving the swellability and dispersibility of Mt in mixtures of ethanol and water remains challenging. Here, we showed that the swellability and dispersibility of Mt in ethanol/water could be significantly enhanced when lithium-Mt (Li-Mt) was intercalated by zwitterionic surfactant lauramidopropyl betaine (LPB). The binding mechanism of the LPB intercalate to Li-Mt originated from a combination of van der Waals forces, ion-dipole interaction, and electrostatic attraction. Due to the synergistic effect of Li+ and LPB, the comodified Mt (LPB-Li-Mt) exhibited excellent swellability, dispersibility, and rheological properties. The structure, morphology, zeta potential, dispersibility, and gel-forming performance of LPB-Li-Mt can be modulated by the concentrations of ethanol in ethanol/water mixtures. When the ethanol concentration increased to 75% v/v ethanol solution, the free swelling of LPB-Li-Mt remained above 80%. The results from X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoemission spectrometry, and small-angle X-ray scattering confirmed the full exfoliation of LPB-Li-Mt at 75% (v/v) ethanol solution. The formation of a stable colloidal LPB-Li-Mt dispersion in a mixture of ethanol/water might be derived from the association between water molecules and the Li+, the hydrophobic interaction, and the ion-dipole of ethanol with the LPB molecules. The findings provide a guide for improving dispersion and swelling of Mt and modified ones in water-miscible organic solvents.

Removal of Aflatoxin B1 and Zearalenone in Mixed Aqueous Solution by Palygorskite-Montmorillonite Materials In Situ Prepared from Palygorskite Mineral

In view of the animal feeds inevitably contaminated by multiple mycotoxins, eco-friendly and efficient palygorskite-montmorillonite (Pal-Mt) materials were prepared to remove polar aflatoxin B₁ (AFB₁) and weak polar zearalenone (ZEN) from mixed mycotoxins aqueous solution. The adsorption properties and bonding mechanisms between Pal-Mt materials and mycotoxins (AFB₁ and ZEN) were investigated systematically. The as-prepared Pal-Mt showed excellent adsorption capacity for AFB₁ and ZEN in single- and binary-mycotoxin systems, indicating the effectiveness of Pal-Mt acting as multiple mycotoxin adsorbents. The kinetics of adsorption for ZEN was fast due to the adsorption on the external surface (film and intraparticle diffusion), while AFB₁ molecules permeated into mesopores after the external adsorption for the more planar structure. Adsorption isotherms demonstrated that heterogeneous surface adsorption appeared between Pal-Mt and AFB₁, and monolayer adsorption occurred on Pal-Mt and ZEN for different polarities of mycotoxins. Thermodynamic parameters illustrated that the adsorption process of both AFB₁ and ZEN onto Pal-Mt was spontaneous and endothermic. The adsorption mechanism studies suggested that hydrogen bonding, electrostatic attraction, calcium bridging linkage, and ion-dipole played fundamental roles in the interaction between Pal-Mt and these two mycotoxins.

Research Progress of Safety of Zearalenone: A Review

Zearalenone, a mycotoxin produced by fungi of the genus Fusarium, widely exists in animal feed and human food. The structure of zearalenone is similar to estrogen, so it mainly has estrogenic effects on various organisms. Products contaminated with zearalenone can pose risks to animals and humans. Therefore, it is imperative to carry out toxicological research on zearalenone and evaluate its risk to human health. This paper briefly introduces the production, physical, and chemical properties of zearalenone and the research progress of its toxicity kinetics, focusing on its genetic toxicity, reproductive toxicity, hepatotoxicity, immunotoxicity, carcinogenicity, endocrine interference, and its impact on intestinal health. Finally, the progress of the risk assessment of human exposure is summarized to provide a reference for the follow-up study of zearalenone.

Evaluation of nano-silica, microwave heating, and ultraviolet irradiation effects on zearalenone detoxification in sunflower oils

In the present study, we report three methods of silica nanoparticles (SNPs) as adsorbent, ultraviolet (UV) irradiation, and microwave heating and evaluate their capabilities in reducing and eliminating zearalenone (ZEN). The offered method not only was used for ZEN detoxification, but also greatly enhanced the sensitivity of ZEN measurement. The aim of this study was to evaluate ZEN concentration in sunflower oil samples by high-performance liquid chromatography (HPLC) method. This method was successfully validated for sunflower oil samples while the limit of detection (LOD) method (signal-to-noise ratio of 3:1) was 0.5 μg/l. The acquired removal data with the HPLC method through SNPs were fitted well with Freundlich isotherm, denoting that the multi-layer adsorption took place on the adsorbent. The equilibrium adsorption capacity of ZEN was 61.02 μg/g in an optimum time of 240 min on SNPs. The experimental results were evaluated by the adsorption kinetic model, which specified the adsorption kinetics of ZEN on SNPs, obeying the pseudo-second order model. This model demonstrated that the sorption rate depended on the sorption capacity but not the concentration of the sorbate. Moreover, the method presented to determine ZEN based on the use of SNPs in sunflower oil was accomplished by the adsorption process. Furthermore, the removal efficiencies of ZEN by SNPs, UV irradiation, and microwave heating were compared and obtained to be 92.1, 96.22, and 37.30%, respectively for determined times. These results confirm the removal efficiency of these methods is sensitive enough to ZEN analysis in sunflower oil samples.

A review of clay based photocatalysts: Role of phyllosilicate mineral in interfacial assembly, microstructure control and performance regulation

Over the past decades, inspired by the outstanding properties of clay minerals such as abundance, low-cost, environmental benignity, high stability, and regularly arranged silica-alumina framework, researchers put much efforts on the interface assembly and surface modification of natural minerals with bare photocatalysts, i.e. TiO₂, g-C₃N₄, ZnO, MoS₂, etc. The clay-based hybrid photocatalysts have resulted in a rich database for their tailor-designed microstructures, characterizations, and environmental-related applications. Therefore, in this study, we took a brief introduction of three representative minerals, i.e. kaolinite, montmorillonite and rectorite, and discussed their basic merits in photocatalysis applications. After that, we summarized the recent advances in construction of stable visible-light driven photocatalysts based on these minerals. The structure-activity relationships between the properties of clay types, pore structure, distribution/dispersion and light absorption, carrier separation efficiency as well as redox performance were illustrated in detail. Such representative information would provide theoretical basis and scientific support for the application of clay based photocatalysts. Finally, we pointed out the major challenges and future directions at the end of this review. Undoubtedly, control and preparation of novel photocatalysts based on clays will continue to witness many breakthroughs in the arena of solar-driven technologies.

Exploration of adsorption mechanism of 2-phosphonobutane-1,2,4-tricarboxylic acid onto kaolinite and montmorillonite via batch experiment and theoretical studies

Two clay minerals, kaolinite (Kaol) and montmorillonite (Mt) with different crystal structures were chosen to investigate the comparative adsorption of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) through batch control experiments and theoretical studies. The systematical isotherm and kinetic studies agreed with Langmuir model and pseudo-second-order model, confirming a monolayer and chemisorption interaction process, respectively. The maximum removal capacities of Kaol and Mt for PBTC were 72.297 mg/g and 121.163 mg/g at pH=3.0 and T=298 K, respectively. Furthermore, the adsorption mechanisms were investigated by molecular dynamic (MD) simulations and density functional theory (DFT). The Interface force field (IFF) was firstly introduced into Materials Studio package to explore the microscopic mechanism of clay mineral interface. The dynamics behaviors verified that the oxygen (O) atom of carboxyl group has stronger affinity at the external surface of Mt, which consistent with the experimental data well. For DFT calculations, quantitative analysis around molecular van der Waals (vdW) surface was adopted to predict reactive sites for the electrophilic reaction. Independent Gradient Model (IGM) and Hirshfeld surface analyses in Multiwfn indicated that the high adsorption effect mainly attributes to hydrogen bond action. These findings improve our ability to explore the related properties occurring at the interface of different clay minerals.

The adsorption characteristics and mechanism of montmorillonite with different layer charge density for alkyl ammonium with different carbon chain length

The crystal chemical properties of montmorillonite and the length and amount of straight alkyl ammonium chain affect the adsorption characteristics of alkyl ammonium on montmorillonite.

Nonlinear sorption of phenols and anilines by organobentonites: Nonlinear partition and space limitation for partitioning

Organobentonites, i.e., bentonites coated with surfactants such as cetyltrimethylammonium (CTAB), are superior and low-cost sorbents for removal of organic contaminants from wastewater. Nonlinear sorption of polar organic compounds such as phenols and anilines by organobentonites were widely observed and interpreted by adsorption mechanism. However, in this study, it was observed that the nonlinear sorption of phenols and anilines by CTAB coated bentonites (CTAB-bentonites) should be attributed to nonlinear partition mechanism with the additional space limitation in CTAB-bentonites for nonlinear partitioning, rather than adsorption mechanism. This nonlinear partition mechanism is supported by that (i) organobentonites is a partition medium, identified by the linear isotherms of polycyclic aromatic hydrocarbons (PAHs) and nitrobenzenes; (ii) sorption coefficients (logK_d), the ratio of adsorbed amount (q_e) to equilibrium concentration (C_e), and Dubinin-Ashtakhov (DA) model fitted sorption capacity (logQ⁰) of organic compounds, by a given CTAB-bentonite, are positively correlated with their octanol-water distribution coefficients (logK_OW) and solubility in octanol (logS_o) respectively; (iii) logK_d and logQ⁰ of a given organic compound by CTAB-bentonites are positively correlated with organic carbon contents (f_oc) of CTAB-bentonites, but not specific surface area. Specific interaction (i.e., hydrogen-bonding interaction), in addition to van der Waals force, is responsible for the nonlinear partitioning of phenols and anilines into CTAB-bentonites, because of the positively linear relationship between DA model fitted sorption affinity (E) and hydrogen-bonding donor parameter (α_m) of organic compounds. These results could help the recognizing of the nonlinear sorption behaviors of organic compounds by organobentonites and promote their environmental applications in wastewater treatment.