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• Hierarchically MgO-based mesoporous adsorbent (CH-5) derived from hydromagnesite was obtained. • CH-5 showed superior adsorption efficiency (69.60 mg/g) towards fluoride in aqueous. • The adsorption performance of CH-5 kept stable from pH=5 to 11. • The prepared adsorbent can be recycled easily at least five times by re-calcination. Hierarchically mesoporous adsorbent derived from natural hydromagnesite with remarkable adsorption capacity for fluoride (F−) has been synthesized through the facile one-step calcination. Various characterizations confirmed that calcination temperature was directly correlated with their crystallite structures, surface properties, and adsorb ability. The hydromagnesite calcined at 500 °C (CH-5) exhibits the highest adsorption capacity and rate towards F−. The F− adsorption isotherm data was explored by both Langmuir and Freundlich model and the maximum adsorption capacity of CH-5 was 69.6 mg/g. Kinetic study revealed that the adsorption kinetics follows the pseudo-second-order model, suggesting the chemisorption mechanism. Regeneration study showed that the adsorption ability for fluorine can be completely recovered by calcining at 500 °C, and after five cycles, the adsorption ability is not significantly weakened. After detailed evaluation, the enhancement mechanism of the calcined product can be attributed to relatively higher specific surface area and exposed more magnesite active sites due to the maintenance of the intrinsic three-dimensional layer structure during the dehydration and decarbonation, which were responsible for the striking adsorption abilities. The green adsorbent originated from natural mineral with the characteristics of low cost, high adsorption ability and recoverability is advantageous for fluoride-containing wastewater treatment. [ABSTRACT FROM AUTHOR]

Diatomite-based X zeolite was obtained and its crystallinity, morphology, and interface properties were investigated by XRD, BET, SEM, EDS, and XRF. The obtained X zeolite possessed a unique meso-microporous structure and showed good ion exchange properties for Cu2+ and Zn2+. The pseudo-second-order model and Langmuir isotherm model can best describe the adsorption kinetics and isotherms of Cu2+ and Zn2+, respectively. The maximal adsorption capacities of X zeolite for Cu2+ and Zn2+ were 146 and 195 mg/g at 323 K, respectively. Meanwhile, the adsorption process for Cu2+ and Zn2+ were chemical adsorption and ion exchange, respectively. Furthermore, the adsorption data turned out to be an endothermic and spontaneous process. Compared with other reported materials, the adsorption capacity of X zeolite synthesized from diatomite was among the highest. Therefore, it could be a promising adsorbent for the disposal of wastewater that contains metal ions. [ABSTRACT FROM AUTHOR]

Mineral-based photocatalyst is a promising alternative to eliminate the volatile organic compounds (VOCs) air pollutants because of its low-cost and environmental-friendly merits. Herein, BiOCl/TiO 2 /sepiolite ternary heterogeneous photocatalyst was synthesized through a facile hydrolysis-precipitation method combining with the calcination crystallization procedure. The gaseous formaldehyde (HCHO) was employed as target pollutant to evaluate the photocatalytic activity of as-synthesized samples. The results indicated that BiOCl/TiO 2 /sepiolite composite performed much significantly higher adsorption and decomposition capacity for HCHO than pure TiO 2 , BiOCl and TiO 2 /BiOCl under solar and visible light. Based on the characterizations and density function theory (DFT) simulation results, the enhanced photocatalytic activity was mainly attributed to the synergistic effect between TiO 2 /BiOCl and sepiolite through the formation of ternary heterojunction. Such structure could lead to the higher adsorption capacity which can provide more reactive sites, and stronger light response ability as well as faster separation efficiency of photoinduced carriers forming more active radicals during the degradation process. Radical scavenger tests and ESR results indicated that photogenerated holes was the main active species in the reaction system. Overall, this study provides an insight into the design and synthesis of environment-friendly and high-effective heterogeneous composite for practical indoor formaldehyde removal. A facile hydrolysis-precipitation method was employed to synthesize the low-cost and environmental-friendly BiOCl/TiO 2 /sepiolite ternary heterogeneous photocatalyst for high-effective removal of indoor HCHO. Image 1 • Ternary heterogeneous BiOCl/TiO 2 /sepiolite composite was synthesized. • The as-prepared composite shows superior HCHO photodegradation efficiency. • The effect of calcination temperature on the HCHO degradation was first studied. • Potential mechanisms for enhanced activity of composite were analyzed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Natural porous minerals were used as VOCs adsorbents. • Adsorption capacity of mineral is linearly related to its specific surface area. • Models fit breakthrough curves, isotherm and kinetic processes well. • The acid stellerite could be a promising adsorbent for VOC adsorption. Abstract The abundance of natural porous minerals and their low cost make them the potential adsorbents for VOCs (volatile organic compounds). In this paper, three natural minerals (diatomite, stellerite and vitric tuff) and their corresponding acid-treated minerals were used as adsorbents. The adsorption performances of minerals were investigated by the adsorption breakthrough curves of VOCs. The results indicated that the properties of organic compounds such as boiling point and polarity and the surface area and pore volume of minerals had obvious effects on the adsorption of VOCs over minerals. Increasing adsorption temperature and relative humidity would have negative effects on the VOC adsorption of minerals. The adsorption capacity of 2-heptanone over acid stellerite decreased by 7.2% as the temperature rose from 25°C to 45°C. The adsorption capacity of acid stellerite for 2-heptanone reduced by 60.9% when relative humidity increased from 0% to 75%. Minerals were tested for five adsorption-regeneration cycles to study the reusability. Better fittings of Thomas model, pseudo-first order kinetics model, and Freundlich model were showed in fitting the adsorption. Overall, porous minerals with high specific surface area and pore volume have promising prospect in VOCs adsorption. [ABSTRACT FROM AUTHOR]

• Organo-montmorillonites (NZMts) modified by binary surfactant mixtures were synthesized. • The NZMts exhibit enhanced detoxification efficiency for both AFB1 and ZER. • The adsorption enhancement mechanism of NZMts was proposed. • This study provides new insight for multifunctional mycotoxin adsorbents. To solve the problem of simultaneous adsorption of polar and weak polar mycotoxins, organo-montmorillonites modified by binary surfactant mixtures (NZMts), including polyoxyethylene ether (OP-10) and lauramidopropyl betaine (LAB-35), were synthesized for the simultaneous removal of aflatoxin B 1 (AFB 1) and zearalenone (ZER). The microstructure, interface and pore structure characteristics of NZMts were investigated through different technologies. The results show that the obtained NZMts modified by binary surfactant mixtures have different structural configurations, higher carbon content and stronger hydrophobicity compared with organo-montmorillonites modified by single surfactant. More importantly, the obtained adsorbents show significant improvements on the detoxification efficiency of both AFB 1 and ZER. The pH has less effect on the adsorption of NZMts compared with the control samples modified by single surfactant, suggesting that NZMts are more stable in different pH environments. In addition, the adsorption mechanisms of NZMts to AFB 1 and ZER were proposed based on the characterizations and adsorption isotherms. It is indicated that NZMts combines with AFB 1 mainly through the hydrophobic interaction and ion dipole action, while with ZER mainly through hydrophobic interaction. The as-received NZMts with more hydrophobic property effectively enhance the adsorption capacities of weak polar and non-polar mycotoxins, providing a new orientation for multifunctional mycotoxin adsorbents. [ABSTRACT FROM AUTHOR]

• TiO 2 nanoparticles were rationally monodispersed on the kaolinite surface. • The composite's reaction rate constant is about 6.90 times higher than that of pure TiO 2. • The synergistic effect between kaolinite and TiO 2 charged for performance enhancement. • This study provides a promising candidate for wastewater treatment. Lamellar kaolinite supported monodispersed TiO 2 was prepared through rational design and 0D/2D structural assembly, which showed significantly improved photocatalytic performance towards ciprofloxacin. After systematic evaluation, the pseudo-first-order kinetic constant rate of TiO 2 /kaolinite composite can reach to 0.04549 min−1, which was 6.90 and 1.81 times higher than that of pure TiO 2 and P25, respectively. The nano-TiO 2 /kaolinite composite photocatalyst also displayed good reusability performance, only a slight decline occurred after four repeated experiments, which is beneficial for the large-scale application of photocatalysts. Various characterizations indicated that enhanced photocatalytic performance can be ascribed to the synergistic effect between natural kaolinite and the well distributed TiO 2 , which enhanced the light absorption ability, assisted the dispersion of pure TiO 2 , resulted in co-catalysis effect, improved the separation facilitation of photo-induced carriers and promoted the stronger adsorption capacity, etc. These merits effectively regulated the carriers' lifetime and migration velocity of the photogenerated charge carriers. Considering the excellent properties of natural kaolinite (low cost, abundance, stability, etc.), our study provides a promising candidate for effective degradation of trace amounts of pharmaceutical and personal care product (PPCP) or contaminants with potential high-toxic risk. [ABSTRACT FROM AUTHOR]

• A porous calcium silicate hydrate (CSH) material was prepared based on opoka. • The CSH has abundant mesoporous, large specific surface area and pore volume. • CSH exhibited more excellent humidity control performance than references. • The enhanced properties should be attributed to the improved porous structure. In this work, a porous calcium silicate hydrate (CSH) humidity control material was prepared by hydrothermal synthesis with opoka (ROP) and slaked lime. The microstructures and humidity control properties of the prepared sample were characterized and analyzed in detail. Results show that CSH possesses plenty of mesoporous structures with the pore size range of 3–20 nm, which are superior to ROP. The maximum moisture adsorption capacity of CSH is about 2–3 times of ROP. The superior humidity control performance of CSH can be attributed to the increase of specific surface area and pore volume and the more reasonable and uniform pore size distribution. Moreover, CSH also exhibits good reusability within three cycles of adsorption/desorption. Furthermore, the synthesized CSH was added to an interior wall coating to test its humidity control performance in practical building materials. The result indicated that the moisture adsorption capacity of the coating with CSH in 24 h at high humidity can reach 110 g/m2, and the moisture desorption capacity can also reach 70 g/m2. The as received CSH shows excellent humidity control performance and can be used as a smart indoor humidity control material for various construction applications. [ABSTRACT FROM AUTHOR]

This study evaluated the adsorption of five volatile organic compounds (VOCs) on Opoka, precipitated silica, and palygorskite, to elucidate the effect of their pore size on VOCs adsorption. The adsorption capacity of these adsorbents is not only highly correlated with their surface area and pore volume, but also notably improved by the presence of micropores. The variation in adsorption capacity for different VOCs was primarily influenced by their boiling point and polarity. Palygorskite, which had the smallest total pore volume (0.357 cm3/g) but the largest micropore volume (0.043 cm3/g) among the three adsorbents, exhibited the highest adsorption capacity for all tested VOCs. Additionally, the study constructed slit pore models of palygorskite with micropores (0.5 and 1.5 nm) and mesopores (3.0 and 6.0 nm), calculated and discussed the heat of adsorption, concentration distribution, and interaction energy of VOCs adsorbed on different pore models. The results revealed that the adsorption heat, concentration distribution, total interaction energy, and van der Waals energy decrease with increasing pore size. The concentration of VOCs in 0.5 nm pore was nearly three times that in 6.0 nm pore. This work can also provide guidance for further research on using adsorbents with mixed microporous and mesoporous structures to control VOCs. [Display omitted] ● Adsorption behavior and related mechanisms of 3 adsorbents on VOCs were studied. ● The adsorption capacity was influenced by boiling points and polarities of VOCs. ● The micropores of an adsorbent can greatly improve its ability to adsorb VOCs. ● Effect of palygorskite pore size on VOCs adsorption was studied by simulation. [ABSTRACT FROM AUTHOR]

To overcome rapid electron-hole recombination and low adsorption capacity of single g-C 3 N 4 photocatalyst, the present work reports on the fabrication of two kinds of visible-light-driven composite photocatalysts (g-C 3 N 4 /kaolinite and g-C 3 N 4 /illite composites). 2D/2D assembly was successfully achieved in this work. Furthermore, the as-synthesized composites exhibited significantly enhanced photocatalytic activity under visible-light irradiation, whose reaction rate constants were almost 4.13 times (g-C 3 N 4 /kaolinite) and 3.18 times (g-C 3 N 4 /illite) that of pure g-C 3 N 4 . A plausible reaction mechanism over the as-prepared composite photocatalysts was also proposed based on the experimental results obtained. The photocatalytic enhancement of synthesized composites should be attributed to the intimate interface contact between g-C 3 N 4 and layered minerals, resulting in better dispersion performance, higher charge separation efficiency as well as stronger adsorption ability. [ABSTRACT FROM AUTHOR]

This work aims to prepare and characterize novel organo-montmorillonites (OMts) using a nonionic surfactant - octylphenol polyoxyethylene ether (OP-10), and apply the materials for the removal of cationic organic dyes. The nonionic surfactant OP-10 can be successfully intercalated into the interlayer of montmorillonite and the obtained OMts still keep cation exchange capacity. The structural configuration of surfactant molecules between clay mineral layers varies from the surfactant loadings. Moreover, OMts with higher surfactant loadings have higher organic carbon content but lower specific surface area. The prepared OMts showed enhanced adsorption capacities towards cationic organic dye methylene blue (MB), and the adsorption amount increases with an increase of surfactant loading. The high adsorption capacity can be attributed to the fact that the novel OMts still keep cationic exchange capacity and OP-10 has plentiful polyoxyethylene ether chains in its molecule structure, which can capture MB molecules through hydrogen bonding. A probable mechanism for the removal of MB was proposed to be a synergistic effect of ion exchange, partition adsorption, hydrogen bonding and electrostatic interactions. Kinetic and isotherm data could be fitted with pseudo-second order model and Langmuir isotherm. The adsorption thermodynamics study has proved the spontaneous and endothermic nature of the adsorption process. The nonionic surfactant modified OMts could be promising candidate adsorbents for the removal of cationic organic dyes. [ABSTRACT FROM AUTHOR]

Mesoporous silica MCM-41 was synthesized by a facile hydrothermal treatment using sodium silicate extracted from natural Opoka as the Si source. The dynamic adsorption and desorption of organic vapors mixture on the MCM-41 were investigated. Characterization of the textural properties of the samples showed that the sample synthesized with a molar ratio of CTAB/Si = 0.16 possessed the largest specific surface area (988 m2/g) and pore volume (1.02 cm3/g), also uniform pore size distribution centered at 2.8 nm. The adsorption capacity of this sample for organic vapors mixture improved remarkably over raw Opoka and reached 158.5 mg/g at 20 ℃, which is comparable to that of commercial activated carbon. The reusability of the adsorbent was tested by 5 adsorption and regeneration cycles. Obtained results demonstrate that the MCM-41 adsorbent can be easily regenerated by thermal desorption in air, and the cumulative heel on the adsorbent can be markedly reduced by increasing the desorption temperature, making it a promising adsorbent for VOCs abatement. ga1 • MCM-41 was prepared from natural Opoka via hydrothermal treatment. • Effect of template on the microstructure of MCM-41 was studied. • Synthesized MCM-41 has a much higher surface area compared to the raw opoka. • MCM-41′s VOC adsorption capacity is comparable to activated carbon. • MCM-41 can be regenerated more efficiently and easily than activated carbon. [ABSTRACT FROM AUTHOR]

Mycotoxins contamination has been a worldwide long-standing issue, which poses tremendous threats to human health and food security. However, the detoxification of various mycotoxins, especially apolar species, is still a big challenge at present. In this study, carbon nanoparticles derived from biopolymer chitosan (Cts) and rectorite supported Cts carbon nanocomposite (Cts@Rec) were fabricated via hydrothermal treatment as efficient mycotoxin adsorbents for apolar zearalenone (ZER). Microstructural analysis revealed that Cts nanoparticles with smaller sizes uniformly distributed on the surface of rectorite, forming the Cts@Rec biocomposite. The obtained two adsorbents contained high organic carbon contents and large specific surface areas, which exhibited superior adsorption efficiency towards ZER. Kinetic study indicated that the adsorption of ZER on Cts and Cts@Rec reached equilibrium within 120 min, and the adsorption process fitted pseudo-second-order kinetic model better. The adsorption isotherms of ZER on both adsorbents matched obviously with linear model, which implied the existence of adsorption/partition model mechanism. The adsorption capacities were found to be positively correlated to the organic carbon contents and specific surface areas, suggesting that organic matter functioned as partition medium for ZER and the enhanced specific surface areas provided sorption sites for ZER. Furthermore, no desorption happened when changed the simulated pH based on the values from gastric fluid to intestinal fluid, confirming the feasibility of resultant Cts and Cts@Rec biocomposite as mycotoxins adsorbents in vivo. Unlabelled Image • Rectorite supported chitosan biocomposite (Cts@Rec) were easily fabricated. • Cts@Rec showed superior adsorption efficiency towards apolar ZER. • The adsorption performance of Cts@Rec kept stable from pH = 3.5 to 6.5. • Hydrophobic interaction charged for the adsorption process of Cts@Rec. [ABSTRACT FROM AUTHOR]