Macroporous Network Research Articles

Hierarchical three-dimensional graphene-based carbon material for high-performance lithium ion batteries

Hierarchical three-dimensional graphene-based carbon materials have been successfully prepared via a template-assisted approach. It is found that the structure, morphology, graphitization degree, surface area and pore volume for the obtained carbon materials could be easily controlled by adjusting the amount of reactant and template. The results show that the obtained hierarchical nanostructured carbon material possesses a very stable reversible capacity of 395 mAh g−1 at 1C and exhibits extremely high reversible capacity of 163 mAh g−1 at the high rate of 20C. The large macroporous network and small mesopores in the materials can facilitate electrolyte and lithium ion transportation. The hollow carbon nanoparticles composed of stacked graphene can favor the electron diffusion within the materials. The micropores in the carbon materials can also increase the reversible capacity.

Colloidal Gelation through Thermally Triggered Surfactant Displacement.

Colloidal systems that undergo gelation attract much attention in both fundamental studies and practical applications. Rational tuning of interparticle interactions allows researchers to precisely engineer colloidal material properties and microstructures. Here, contrary to the traditional approaches where modulating attractive interactions is the major focus, we present a platform wherein colloidal gelation is controlled by tuning repulsive interactions. By including amphiphilic oligomers in colloidal suspensions, the ionic surfactants on the colloids are replaced by the nonionic oligomer surfactants at elevated temperatures, leading to a decrease in electrostatic repulsion. The mechanism is examined by carefully characterizing the colloids, and subsequently allowing the construction of interparticle potentials to capture the material behaviors. With the thermally triggered surfactant displacement, the dispersion assembles into a macroporous viscoelastic network and the gelling mechanism is robust over a wide range of compositions, colloid sizes, and component chemistries. This stimulus-responsive gelation platform is general and offers new strategies to engineer complex viscoelastic soft materials.

Characterization of Root Architectures and Soil Macropore Networks Under Different Ecosystems Using X-ray CT Scanning in the Qinghai Lake Watershed, NE Qinghai–Tibet Plateau

The objectives of this study were to visualise and quantify the soil macropore networks and root architectures within intact soil columns under different ecosystems and to investigate the influences of roots on soil macropore network characteristics. Intact soil columns with diameters of 110 mm and lengths of 400 mm were taken from alpine Kobresia meadow, interspace meadow patches of Potentilla fruticosa shrubs, Potentilla fruticosa shrubs and Artemisia sphaerocephala shrubs in the Qinghai Lake watershed of the NE Qinghai–Tibet Plateau. A Philips medical X-ray CT scanner was used to simultaneously visualise and quantify the soil macropore networks and root architectures. The results showed that macropores and taproots were concentrated in the top 0–150 mm. The root volume density of the P. fruticosa shrub was greater than that of the interspace meadow patches of P. fruticosa shrub and that of the alpine Kobresia meadow. The macroporosity and the root volume density of the soils under the P. fruticosa shrub patches were significantly greater than those in the soils under the other sites. The root volume density was significantly correlated with the macroporosity for the A. sphaerocephala shrubs (R2 = 0.88) and the P. fruticosa shrubs (R2 = 0.73). There were significant positive correlations between the volume density, branch density and mean angle of the roots and those of the macropores. Shrub roots invasion played an important role in the formation of macropores. The root volume density was the most important factor for the quantified characteristics and distributions of the macropores.

Ordered macro/micro-porous metal-organic framework of type ZIF-8 in a steel fiber as a sorbent for solid-phase microextraction of BTEX.

An ordered array of macropores on microporous metal-organic framework crystals was developed. This array facilitates analyte diffusion in microextraction applications. A prototypical zeolitic imidazolate framework (ZIF-8) was synthesized in the interstitial voids of a polystyrene bead packing of sub-μm polystyrene beads. After removal of polystyrene by dimethylformamide, a single-crystal ordered macroporous ZIF-8 material (SOM-ZIF-8) was obtained. The resulting μm-sized SOM-ZIF-8 crystals are based on a fully-microporous structure containing a macroporous network. The SOM-ZIF-8 crystals were placed in a stainless-steel fiber and applied as a sorbent for the extraction of benzene, toluene, ethylbenzene, and xylenes (BTEX) by headspace solid-phase microextraction (HS-SPME). The fiber was applied to the HS-SPME of BTEX from wastewater samples followed by GC with flame ionization detection. A Plackett-Burman design and Box-Behnken design were carried out to evaluate the variables affecting the method. Figures of merit include (a) limits of detection of 1.0-12ng·L-1, (b) linear ranges of 0.004-50μg·L-1, (c) relative standard deviations of 4.6-6.7%, and (d) excellent fiber-to-fiber reproducibility (5.6-6.7% for n = 3). Spiking recoveries between 92 and 106% were obtained for BTEX analysis in wastewater samples. The introduction of an ordered macroporous network on microporous ZIF-8 crystals enhanced analyte uptake. This increases the extraction performance by a factor of 2.5-3.1 when compared to analogous ZIF-8 crystals that lack templated macropores. Graphical abstract BTEX extraction is enhanced by templating an ordered macroporous network in microporous crystals as exemplified with the single-crystal ordered macropore zeolitic imidazolate framework-8 (SOM-ZIF-8). Graphical Abstract contains poor quality of image inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.The file in original format has been attached.

Nanocrystals FAU-X monoliths as highly efficient microreactors for cesium capture in continuous flow

Abstract The performances of binderless FAU-X monoliths (0.5 × 3 cm) build of nanocrystals featuring hierarchical trimodal porosity (micro-/meso-/macroporosity) in decontamination Cs-containing effluents have been evaluated. They have been compared to those obtained with newly synthesized FAU-X particles (1 mm) build with nanocrystals. Data have been confronted to those recently reported for a benchmark reference Cs+ adsorbent Sorbmatech®, based on copper hexacyanoferrate nanoparticles (15 nm) immobilized into mesoporous silica particles (250–500 μm) (Cu-HCF@SiO2). FAU-X monoliths show high rate of adsorption in batch in less than 2 min, much faster than Cs+ adsorption in FAU-X particles (60 min). This result highlights the importance of a homogeneous macropore network in adsorbents to enhance mass transport and access to the zeolite active sites. FAU-X monoliths with 20 μm macropore diameter have been used in continuous flow experiments for sequestering Cs+ (0.5 mmol/L) in mineral drinking water containing competing cations (Ca2+, Mg2+, Na+, K+) with flow rates of 0.5–1 mL/min, corresponding to Darcy rates of 1.5–3 m/h. FAU-X monoliths are very efficient for Cs+ removal and show ideal steep breakthrough curves characteristic of fast diffusion. FAU-X monoliths are as excellent as Cu-HCF@SiO2 and could represent an alternative adsorbent for safer processes, avoiding the handling of powders or particles. Above all, this study reveals the unique hydrodynamic behavior of FAU-X monoliths and opens the route for process intensification using FAU-X in continuous flow.

Facile synthesis of mesoporous WO3@graphene aerogel nanocomposites for low-temperature acetone sensing

Nanocomposites constructed by combining mesoporous metal oxides and graphene have received tremendous attention in wide fields of catalysis, energy storage and conversion, gas sensing and so on. Herein, we present a facile interface-induced co-assembly process to synthesize the mesoporous WO3@graphene aerogel nanocomposites (denoted as mWO3@GA), in which graphene aerogel (GA) was used as a macroporous substrate, mesoporous WO3 was uniformly coated on both sides of graphene sheets through a solvent evaporation-induced self-assembly (EISA) strategy using diblock copolymer poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a template. The resultant mWO3@GA nanocomposites possess well-interconnected macroporous graphene networks covered by mesoporous WO3 layer with a uniform pore size of 19 nm, high surface area of 167 m2/g and large pore volume of 0.26 cm3/g. The gas sensing performance of mWO3@GA nanocomposites toward acetone and other gases was studied, showing a high selectivity and great response to acetone at low temperature of 150 °C, which could be developed as a promising candidate as novel sensors for VOCs detection.

Camponotus japonicus burrowing activities exacerbate soil erosion on bare slopes

As soil ecosystem engineers, ants considerably affect soil physical and chemical properties, and further accordingly affect soil erosion. However, few study was made on studying the effects of ant-burrowing activities on soil erosion previously. This study quantified the impacts of ant (Camponotus japonicus)-burrowing activities on runoff and soil erosion rates. Simulated laboratory rainfall experiments were undertaken on six soil tanks filled with clay-loam soil classified as a cumulic anthrosol, three of which introduced with ant colonies for two days and the other three were without ant colonies, under 40, 80, and 120 mm h−1 of rainfall intensities and a slope of 15°. Results showed that ants made mounds with a bulk density of 0.75 g cm−3, which was lower than that of the soil matrix, i.e. 1.34 g cm−3. Soil erosion rates for the tanks with ants were 6.78, 36.90, and 62.00 g m−2 min−1 under three rainfall intensities of 40, 80, and 120 mm h−1, which were much higher than those of 3.94, 23.49, and 44.48 g m−2 min−1 for the tanks without ants. Ant nests reduced the runoff rate by 31%, 20% and 13% compared with those without ants and enhanced the soil water storage within 90 cm depth. Ant nests played a positive role in soil water conservation due to the large nest entrance diameter and the continuous macropore network. However, the ant mounds provided a loose erodible material and changed micro-topography of the slope surface, thereby accelerating the rill formation and exacerbating soil erosion. This study can help understand the effects of burrowing insects on soil erosion, which is an important environmental problem on the Loess Plateau.

Composition control in biphasic silicate microspheres on stimulating new bone regeneration and repair of osteoporotic femoral bone defect.

Application of bioactive materials as synthetic bone graft substitutes in regenerative medicine has seen great evolution over the past decades in treating challengeable bone defects. However, balancing the preparation conditions and biological performances of inorganic biomaterials remain a great challenge, especially when there is lack of biomaterial design on how to control component distribution and how pathological bone responds to the biomaterial stimulations and osteogenesis. Here, our objective is to develop yolk-shell Ca-silicate microspheres and to investigate the potential biological performances to overcome the limitations in repair of osteoporotic bone defects. The introduction of β-calcium silicate (CaSiO3 ) or mesoporous bioactive glass (MBG) into self-curing β-dicalcium silicate (Ca2 SiO4 ) cement shell to form spherical granules (CaSiO3 @Ca2 SiO4 , MBG@Ca2 SiO4 ) was to retain the physicochemical property and/or microstructure of each component for optimizing bioactive ion release that could maximize osteostimulation in osteoporosis. We report a scalable shape-controlled mild fabrication protocol to yield the yolk-shell granules, endowing to different phases in yolk layer and interconnected macropore networks in the closely packed granule scaffolds. This unique heterostructure preparation is governed by coaxially aligned bilayer nozzle, inorganic powders and biocompatible binders. Extensive in vitro and in vivo evaluation showed that the CaSiO3 @Ca2 SiO4 and MBG@Ca2 SiO4 granules exhibited many superior properties such as controllable ion release, improved biodegradation and enhanced osteogenic capability in comparison with the pure Ca2 SiO4 @Ca2 SiO4 , thereby opening new mild-condition approach in fabricating osteogenesis-tailored silicate biomaterials for bone regenerative medicine, especially for efficient reconstruction of challenging pathological bone defects.

Three dimensional (3D) nanostructured assembly of MoS2-WS2/Graphene as high performance electrocatalysts

A promising electrocatalyst material composed of 2D layered MoS2-WS2 heterostructure hierarchically assembled into a 3D highly interconnected macroporous network of graphene was facilely fabricated. This in-situ synthesis method involves hydrothermal reaction followed by moderate thermal annealing which guarantees the uniform distribution of the MoS2-WS2 heterojunctions within graphene matrix. The presence of 3D conductive and porous graphene network and the combined merits of MoS2 and WS2 endow the resulting 3D MoS2-WS2/graphene nanohybrids with unique conductivity pathways and channels for electrons and with outstanding electrocatalytic performance towards enhanced hydrogen evolution reaction (HER). This 3D nanohybrid delivered the small overpotential of 110 mV, and the small Tafel slope of 41 mV per dec, demonstrating high HER activity. Furthermore, the resulting nanohybrids exhibit excellent stability as very trivial drop in the current density was noticed even after 2000 cycles. The superior electrocatalytic performance of 3D MoS2-WS2/graphene over other non-precious metal electrocatalysts is accredited to the robust synergism of 2D MoS2-WS2 with 3D graphene that offer ample active sites and improved conductivity for HER. The proposed approach can be further extended to modify other layered transition metal dichalcogenides with hierarchical 3D porous structure as a competent electrocatalysts for HER.

Hierarchical macroporous Si/Sn composite: Easy preparation and optimized performances towards lithium storage

Hierarchical macroporous Si/Sn composites are fabricated via one facile and green dealloying process by etching SiSnAl alloy precursors. The as-made Si/Sn composites consist of three dimensional hierarchical macroporous Si network and bimodal pore channels as the built units with Sn nanoparticles uniformly distributed on the porous surface. Owing to its hierarchical porous architecture and incorporation of Sn nanoparticles, the Si85Sn15 sample delivers much higher specific capacity, superior cycling stability, and better rate capability compared with Si80Sn20 and pure Si anodes. The Si85Sn15 composite presents a steady capacity about 1600 mA h g−1 at 200 mA g−1 in the period of 70 cycles. Even the current rates are set up to 3000 and 4000 mA g−1, Si85Sn15 can still exhibit the high capacities of ∼800 and ∼620 mA h g−1, respectively. In particular, the lithium storage performances of Si85Sn15 composite are superior to those of most other reported Si/Sn or Si/Sn-based anodes. The as-made Si/Sn composite shows the promising application prospect as an alternative anode candidate for lithium-ion batteries with the excellent performances and easy preparation.

Quantification of Three Dimensional Characteristics of Macrofauna Macropores and Their Effects on Soil Hydraulic Conductivity in Northern Vietnam

Soil bioturbation is associated with the production of soil macropores that influence numerous ecological functions such as those associated with water infiltration and the generation of runoff water. This impact is especially important on sloping lands in the tropics that are highly susceptible to erosion. In this study, we questioned the influence of soil biodiversity on soil macropore properties (> 20 mm3) and saturated hydraulic conductivity (Ksat) on sloping land in northern Vietnam. Biostructures found at the soil surface (casts, sheetings and soil excavated on the ground) were used to identify areas colonized either by earthworms, termites or dung beetles, respectively. The influence of soil macrofauna on Ksat was measured in situ using the Beerkan method below bioturbated zones and compared to the surrounding soil without visible biostructures at the soil surface. Undisturbed soil columns were afterwards sampled and scanned by X-ray computed tomography (X-CT). Properties of macropores below each biostructure depicted a large variability, revealing the complexity of the macropore network. Further, galleries made by termites, dung beetles and earthworms were manually isolated from the rest of macroporosity. Galleries made by beetles, termites and earthworms were clearly differentiated on the basis of their diameter, verticality, sphericity, tortuosity, length and number of branches and the fraction of galleries in the top part of the column and. Ksat was most increased by dung beetles (45-fold), then by termites (30-fold) and to a lesser extent by earthworms (16-fold). Relationships between total macropore properties and Ksat showed that the most important properties explaining Ksat were (i) the volume of percolating macropores, (ii) the diameter, (iii) the critical macropore diameter and (iv) the number of macropores. In conclusion, this study confirmed not only the interest in using X-CT for the quantification of macroporosity but also the absence of a clear relationship between aboveground biostructures and macropore properties and functional impacts.

Reconfiguration of macropore networks in a silty loam soil following biochar addition identified by X‐ray microtomography and network analyses

Biochars are widely applied to improve soil pore structures. However, the quantitative effects of biochars on soil macropore networks still remain unclear. In this study, the effects and possible mechanism of biochar application on soil macropore networks were investigated quantitatively by industrial X‐ray microtomography (CT), a pore network model and network analyses. Soil cores of 5 cm in diameter and 10 cm in height were collected from a paddy soil (Typic Haplustalf) without biochar application (CK), and amended with rice straw biochar (RSB), corn straw biochar (CSB) and bamboo biochar (BB) at a rate of 25 Mg ha−1 (w/w). Results revealed that the total and connected macroporosity of the biochar‐amended soil was reduced significantly compared with CK, whereas the reverse was true for the isolated porosity. The three types of biochars exhibited different effects on macropores of the soil, depending on their size and shape. The pore network model and network analyses showed that the physical and topological structures of macropore networks in biochar‐amended soil were clearly reconfigured. The accessibility of these macropore networks was markedly reduced. Our results indicated that the incorporation of biochar did not necessarily increase the soil's macroporosity. The combination of pore network model and network analyses was effective for quantifying key properties of soil macropore networks affected by the incorporation of biochar. The changes in these properties may be used to evaluate the effects of biochar on water, air and nutrient transport.Highlights Effect of biochars on the soil macropore structure was studied by industrial CT. Macropore network structure was quantified by a pore network model and network analyses. Biochar incorporation markedly changed the accessibility of the soil macropore network. The macropore network of soil can be reconfigured following biochar addition.

Improved Sorption‐Enhanced Steam Methane Reforming via Calcium Oxide–Based Sorbents with Targeted Morphology

Calcium oxide (CaO)‐based sorbents for sorption enhanced steam methane reforming (SE‐SMR) that achieve stoichiometric capacity are synthesized via thermal and electrospinning methods. Small CaO crystallites (39 nm) and macroporous intrafiber networks imparted by electrospinning lead to stoichiometric capacities () and uptake kinetics (first order rate constant, k = 8.9 × 10−4 ± 1.8 × 10−5 cm4 mol−1 s−1) at 873 K that are superior to CaO derived from thermal syntheses ( and k < 5.0 × 10−4 ± 2.5 × 10−6 cm4 mol−1 s−1). Al‐doped electrospun CaO samples (Al:Ca ratios of 3:10, 1:10 and 2:10) also exhibit high sorption capacities ( at 873 K) and are stable over multiple reaction‐regeneration cycles (<5% loss in initial capacity after 15+ cycles). X‐ray diffraction and scanning electron microscopy analysis reveal that thermally stable Al‐Ca mixed phases (Ca12Al14O33) mitigate crystallite agglomeration and maintain macroporous structures imparted by electrospinning. Nanofibers and Al‐doped nanofibers (Al:Ca ═ 2:10) exhibit more than a factor of three longer CO2 breakthrough time compared to CaO from marble (1650, 6400, and 7500 mL gsorbent−1 for CaO‐marble, 2Al‐10Ca‐O‐nanofibers, and CaO‐nanofibers respectively) under reforming conditions, with Al‐doped CaO‐nanofibers retaining 94% of their initial performance after ten reforming‐regeneration cycles, indicating their potential as improved sorbents for SE‐SMR processes.

Macroporous hydrogels derived from aqueous dynamic phase separation

A method to generate injectable macroporous hydrogels based on partitioning of polyethylene glycol (PEG) and high viscous polysaccharides is presented. Step growth polymerization of PEG was used to initiate a phase separation and the formation of a connected macroporous network with tunable dimensions. The possibilities and physical properties of this new category of materials were examined, and then applied to address some challenges in neural engineering. First, non-degradable macroporous gels were shown to support rapid neurite extension from encapsulated dorsal root ganglia (DRGs) with unprecedented long-term stability. Then, dissociated primary rat cortical neurons could be encapsulated with >95% viability, and extended neurites at the fast rate of ≈100 μm/day and formed synapses, resulting in functional, highly viable and long-term stable 3D neural networks in the synthetic extracellular matrix (ECM). Adhesion cues were found unnecessary provided the gels have optimal physical properties. Normal electrophysiological properties were confirmed on 3D cultured mouse hippocampal neurons. Finally, the macroporous gels supported axonal growth in a rat sciatic nerve injury model when used as a conduit filling. The combination of injectability, tunable pore size, stability, connectivity, transparency, cytocompatibility and biocompatibility, makes this new class of materials attractive for a wide range of applications.

Incorporating Hierarchy into Conventional Zeolites for Catalytic Biomass Conversions: A Review

Zeolites are promising catalysts that are widely used in petrochemical, oil, and gas industries due to their unique characteristics, such as ordered microporous networks, good hydrothermal stability, large surface area, tunable acidity, and shape-selectivity. Nevertheless, the sole presence of microporous channels in zeolites inevitably restricts the diffusion of bulky reactants and products into and out of the microporous networks, leading to retarded reaction rates or catalyst deactivation. This problem can be overcome by developing hierarchical zeolites which involve mesoporous and macroporous networks. The meso- and macro-porosities can enhance the mass transport of molecules and simultaneously maintain the intrinsic shape selectivity of zeolite microporosity. Hierarchical zeolites are mainly developed through post-synthesis and pre-synthesis or in situ modification of zeolites. In this review, we evaluated both pre-synthesis and post-synthesis modification strategies with more focus on post-synthesis modification strategies. The role of various synthesis strategies on the intrinsic properties of hierarchical zeolites is discussed. The catalytic performance of hierarchical zeolites in important biomass reactions, such as catalytic pyrolysis of biomass feedstock and upgradation of bio-oil, has been summarized. The utilization of hierarchical zeolites tends to give a higher aromatic yield than conventional zeolites with microporosity solely.

Terphen[n]arenes and Quaterphen[n]arenes (n=3–6): One‐Pot Synthesis, Self‐Assembly into Supramolecular Gels, and Iodine Capture

AbstractHerein, two new classes of macrocyclic compounds, terphen[n]arenes (TPns) (n=3–6) and quaterphen[n]arenes (QPns) (n=3–6), were designed and synthesized by a one‐step condensation reaction in relatively high yields. They comprise 2,2′′‐dimethoxy terphenyl and 2,2′′′‐dimethoxy quaterphenyl monomers, respectively, linked by methylene bridges. Given their long and rigid monomers, TPns and QPns have much larger cavities and better self‐assembly properties than classic macrocycles. More interestingly, the cyclic pentamers and hexamers TP5, TP6, QP5, and QP6 formed supramolecular organogels, which were composed of interwoven fibers, nanosheets, or entangled macropore networks formed by multiple face‐to‐face and edge‐to‐face π⋅⋅⋅π stacking interactions. The xerogel materials effectively captured volatile iodine, not only in aqueous media but also in the gaseous state, and could be recycled multiple times without obvious loss in performance.

Terphen[n]arenes and Quaterphen[n]arenes (n=3-6): One-Pot Synthesis, Self-Assembly into Supramolecular Gels, and Iodine Capture.

Herein, two new classes of macrocyclic compounds, terphen[n]arenes (TPns) (n=3-6) and quaterphen[n]arenes (QPns) (n=3-6), were designed and synthesized by a one-step condensation reaction in relatively high yields. They comprise 2,2''-dimethoxy terphenyl and 2,2'''-dimethoxy quaterphenyl monomers, respectively, linked by methylene bridges. Given their long and rigid monomers, TPns and QPns have much larger cavities and better self-assembly properties than classic macrocycles. More interestingly, the cyclic pentamers and hexamers TP5, TP6, QP5, and QP6 formed supramolecular organogels, which were composed of interwoven fibers, nanosheets, or entangled macropore networks formed by multiple face-to-face and edge-to-face π⋅⋅⋅π stacking interactions. The xerogel materials effectively captured volatile iodine, not only in aqueous media but also in the gaseous state, and could be recycled multiple times without obvious loss in performance.

A three-dimensional macroporous network structured chitosan/cellulose biocomposite sponge for rapid and selective removal of mercury(II) ions from aqueous solution

A novel adsorbent, chitosan/cellulose biocomposite sponge (CCS) for removing Hg(II) ions rapidly and selectively from aqueous solution is successfully fabricated via a facile glutaraldehyde cross-linking reaction and lyophilization. The CCS can be rapidly separated and easily regenerated by simple extrusion compared with most particulate or powder absorbent. In the adsorption tests, the experimental data follows the pseudo-second-order kinetic model and Langmuir isotherm. The CCS uptakes more than 97% of the ultimate adsorption capacity in aqueous solution within 2 min, and the adsorption capacity is derived to be 495 mg/g. Furthermore, the CCS shows good selectivity for removing Hg(II) ions, and the coefficient of selectivity to Hg(II) ions is 461, 227, and 35 times higher than that to Cu(II), Pb(II), and Cd(II) ions, respectively. The mechanism for selective adsorption is elucidated via Fourier transform infrared spectrum (FTIR) and X-ray photoelectron spectroscopy (XPS) spectral analysis before and after adsorption. Density functional theory (DFT) calculations are also performed. Notably, the adsorption capacity retains 85% of its initial value (495 mg/g) after five cycles, indicating excellent reusability of the CCS. Significantly, the applicability of the CCS is evaluated in simulated Hg(II) effluent (PVC production). The results indicate that the removal efficiency of the CCS exceeds 84% of the initial value (11.45 ppm) within just 2 min. The sponge is a portable and eco-friendly composite, thereby has a great potential to decontaminate Hg(II) ions in water treatment.

Sustainable Approach for Cellulose Aerogel Preparation from the DBU–CO2 Switchable Solvent

We report a sustainable and easy approach for the preparation of cellulose-based aerogels from the DBU–CO2 switchable solvent system via a solubilization and coagulation approach followed by freeze-drying. The easy, fast, and mild solubilization step (15 min at 30 °C) allows for a rapid preparation procedure. The effect of various processing parameters, such as cellulose concentration, coagulating solvent, and the superbase, on important aerogel characteristics including density, porosity, pore size, and morphology, were investigated. Density values obtained ranged between 0.05 and 0.12 g/cm3, with porosity values between 92% and 97%. The morphology of the obtained cellulose aerogels was studied using scanning electron microscopy (SEM) showing a random and open large macroporous cellulose network with pore sizes ranging between 1.1 and 4.5 μm, depending on the processing conditions. In addition, specific surface areas determined by N2 adsorption applying the BET equation ranged between 19 and 26 m2/g. The...

Determining Millimeter‐Scale Maps of Cation Exchange Capacity at Macropore Surfaces in Bt Horizons

Core Ideas Coatings determine the cation exchange capacity (CEC) of macropore surfaces. We predicted the millimeter‐scale, 2D spatial distribution of CEC at intact macropores. The approach combined infrared spectroscopy and CEC measurements of small samples. The CEC distribution in clay–organic coatings was similar for two different Bt horizons. During preferential flow in structured soils, solute transport is largely restricted to a complex network of macropores. Clay–organic coatings of macropore surfaces determine soil physicochemical properties relevant for mass transport and carbon and nutrient turnover, such as the cation exchange capacity (CEC). However, due to the lack of an appropriate measurement approach, the small‐scale spatial distributions of the CEC and its quantities are unknown to date. The objective of this work was to develop a method for predicting the millimeter‐ to centimeter‐scale, two‐dimensional spatial distribution of the CEC at intact macropore surfaces. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was used to analyze bulk soil and separated coating material and for intact macropore surfaces as DRIFT mapping. To determine effective CEC (CECeff), a reduction of soil mass down to 0.5 g for use in the standard barium chloride batch method was tested to account for the limited amount of soil material that can be separated from thin macropore coatings. Linear and partial least squares regression analyses were applied to predict the CECeff distribution at intact macropore surfaces for samples from Luvisol Bt horizons from loess (L) and glacial till (T) using DRIFT spectral data. The highest CECeff values were found for coatings and pinhole fillings rich of clay–organic material (L: 38 cmol kg−1; T: 29 cmol kg−1) compared with low CECeff values of uncoated cracks and earthworm burrows that were similar to those of bulk soil (L: 21 cmol kg−1; T: 14 cmol kg−1). The location of millimeter‐ to centimeter‐sized regions with increased CECeff levels at intact macropore surfaces corresponded with the location of clay–organic coatings. The proposed method allows determining the CEC at macropore surfaces to quantify their effect on nutrient transport by preferential flow as well as on plant nutrient supply in macropores that may serve as preferential growth paths for plant roots.