Aerogel Surface Research Articles

Selective adsorption and efficient degradation of oil pollution by microorganisms immobilized natural biomass aerogels with aligned channels

Efficient elimination of organic pollution from wastewater is of great importance for sustainable human development. In this paper, natural biomass of lotus root (LR) and sorghum straw (SS), which showed aligned structure after treatment, was used to prepare efficient, low-cost, selective adsorption and self-floating microbial immobilization materials by hydrophobic modification assembly for the efficient degradation of diesel. By immobilizing microorganisms in aligned structured lotus flower (ALR) and sorghum straw (ASS) aerogels, hydrophobically modifying the aerogel surfaces with SiO2/PDMS, and assembling them with polyurethane foam to form hydrophobically immobilized microbial bilayer structured self-floating composites (SA6-ALR4@SiO2/PDMS and SA6-ASS4@SiO2/PDMS), diesel in water can be selectively adsorbed for biodegradation. The kinetic and thermodynamic parameters of diesel degradation process were investigated by treating oily wastewater and the effect of different carriers on microbial tolerance under different factors (temperature, pH, degradation substrate concentration, salinity) was examined. The results showed that the different carriers were effective in the degradation of diesel. However, the rich vertical aligned channels and excellent self-floating characteristics of SA6-ALR4@SiO2/PDMS accelerated the mass transfer rate between microorganisms and pollutants, achieving a high degradation rate of 96.25% for diesel in 276 h, which was better than that of 33.06% for free microorganisms under the same conditions. The degradation of oily wastewater by immobilized microorganisms follows first order kinetics. Moreover, this degradation process is spontaneous and the ΔG value is less than 0 at different temperatures. Compared with the existing methods using natural biomass to treat oily wastewater or applying only free microorganisms for biodegradation to remove oily wastewater, these methods have the disadvantages of poor selective adsorption, easy settling and low efficiency. It has greater advantages and application potential in on-site oil spill accident treatment, and opens up an effective green channel for the purification of oily wastewater.

Novel and effective hemostats based on graphene oxide-polymer aerogels: In vitro and in vivo evaluation.

In this study, graphene oxide (GO)-based aerogels cross-linked with chitosan (CS), gelatin (GEL), and polyvinyl alcohol (PVA) were characterized and their hemostatic efficiencies both in vitro and in vivo were investigated and compared to commercial materials (ChitoGauze®XR and Spongostan™). All aerogels exhibited highly porous structures and a negative surface charge density favorable to their interaction with blood cells. The in vitro studies showed that all aerogels coagulated >60% of the blood contained in their structures after 240s of the whole-blood clotting assay, the GO-CS aerogel being the one with the highest blood clotting. All aerogels showed high hemocompatibility, with hemolytic rates <5%, indicating their use as biomaterials. Among them, the GO-GEL aerogel exhibited the lowest hemolytic activity, due possibly to its high GEL content compared to the GO amount. According to their blood clotting activity, aerogels did not promote coagulation through extrinsic and intrinsic pathways. However, their surfaces are suitable for accelerating hemostasis by promoting alternative routes. All aerogels adhered platelets and gathered RBCs on their surfaces, and in addition the GO-CS aerogel surface also promoted the formation of filamentous fibrin networks adhered on its structure. Furthermore, in vivo evaluations revealed that all aerogels significantly shortened the hemostatic times and reduced the blood loss amounts compared both to the Spongostan™ and ChitoGauze®XR commercial materials and to the gauze sponge (control group). The hemostatic performance in vitro and in vivo of these aerogels suggests that they could be used as hemostats for controlling profuse bleedings.

Effect of O/N doping in CNT aerogel film on their nucleic acid hybridization detection ability as electrochemical impedance biosensor

An emerging material CNT aerogel, mitigating nano-level properties of CNT into macro level, has been synthesized using scalable floating catalyst chemical vapor deposition and doped with oxygen/nitrogen via plasma treatment. The dopant leads to formation of a strong space charge layer due to the high surface wetting effect, which is unfavorable for DNA hybridization detection. Bare CNT aerogel showed best sequence selectivity for the detection of DNA hybridization. The present study showed existence of a critical trade-off between doping and presence of huge hydrophilic functional groups on CNT aerogel surface is detrimental for electrochemical impedance bio sensing performance.

Lyophilic and Sorption Properties of Chitosan Aerogels Modified with Copolymers Based on Glycidyl Methacrylate and Alkyl Methacrylates.

This paper discusses the influence of the structure of copolymers based on glycidyl methacrylate and alkyl methacrylates with C6–C18 hydrocarbon side groups on the wettability and sorption properties of surface-modified chitosan aerogels. The grafting of copolymers onto the surface of aerogels was confirmed by elemental analysis, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. As a result of the modification, with an increase in the amount of the hydrocarbon substituent alkyl methacrylate, the surface of the resulting materials became hydrophobic with contact angles in the range of 146–157°. At the same time, the water absorption of the aerogels decreased by a factor of 30 compared to that for unmodified aerogels, while the sorption capacity for light oil, diesel fuel, and synthetic motor oil remained at the level of more than 30 g/g. Chitosan aerogels with grafted copolymers based on glycidyl methacrylate and alkyl methacrylates retain biodegradation capacity; however, compared to unmodified chitosan, this process has an induction period.

Unique superstructure of Pd–Ir aerogel as a robust three-dimensional electrocatalyst

Herein, a novel, facile, fast, and one-step strategy is introduced to synthesize a three-dimensional (3D) Pd–Ir aerogel. The Pd–Ir aerogel is synthesized by reducing metallic ions in the presence of sodium carbonate and formaldehyde, followed by CO2 supercritical drying. Controlling the type of generated nanostructures and the reaction kinetics is adjusted by the sodium carbonate concentration. The change of sodium carbonate concentration is employed for creating an efficient anisotropic condition to create a Pd–Ir aerogel. The aerogel depicts a 3D architecture with a large porosity and an ultra-low density (0.022 g cm−3). This unique architecture illustrates the exceptional electrocatalytic activity and durability owing to the following vital reasons. The 3D architecture with large open pores not only significantly facilitates the accessibility of ethanol molecules to inner active sites but also guarantees the interaction of ethanol molecules with the surface of aerogel. Furthermore, the downfall of durability observed in the Pd/C owing to corrosion can eliminate by the self-supported nature of assembled aerogel. Moreover, the presence of Ir in the structure of aerogel leads to an alteration in the electronic structure of palladium, which facilitates the electrooxidation of ethanol at a high pH environment.

Utilization of UiO-66-NH2@cellulose hybrid aerogel for solid-phase extraction of sildenafil in health products

研究建立了一种基于UiO-66-NH2@纤维素复合气凝胶的高灵敏度固相萃取新方法,与高效液相色谱法联用用于保健品中西地那非的检测。先将纤维素进行醛基和酰肼基的功能化,然后将两种功能化的纤维素通过交联并负载UiO-66-NH2形成复合气凝胶。将此复合气凝胶作为固相萃取的吸附剂使用时,易于收集且不需要外加磁场或者抽真空的辅助作用,操作简单。研究对制备所得的UiO-66-NH2@纤维素复合气凝胶进行了X-射线粉末衍射、扫描电镜、红外光谱和N2吸附等表征,结果显示UiO-66-NH2成功负载于气凝胶的孔道中,纤维素气凝胶掺杂了UiO-66-NH2之后其孔道结构变得规整,并且比表面积增大。研究优化了复合气凝胶中UiO-66-NH2的负载量对萃取的影响,高比例的负载量有利于西地那非的富集,并且最高的负载率为50%。研究优化了影响西地那非富集效率的实验条件,包括溶液pH、萃取时间、洗脱剂类型、洗脱时间、洗脱体积和离子强度。采用安捷伦Zorbax Eclipse Plus C18色谱柱(150 mm×4.6 mm, 5 μm)进行分离,以含0.1 mol/L三乙胺的磷酸盐水溶液(pH=6.50)-乙腈(30∶70, v/v)为流动相进行洗脱,检测波长为292 nm。在最佳的萃取条件下(pH为9.0,萃取时间为60 min,洗脱剂为乙腈,洗脱液体积为3×2 mL,洗脱时间为40 min),该分析方法的线性范围为10~2000 ng/mL (相关系数R2=0.9949),检出限(LOD, S/N=3)为2.85 ng/mL,富集因子为59.17。将该方法用于保健品中西地那非的萃取,所得回收率为74.93%~89.12%,相对标准偏差为2.8%~5.3%,表明了方法的回收率和精密度良好,说明了该方法具有应用于保健品中西地那非日常检测的潜力。

Multicomponent Composite Membrane with Three-Phase Interface Heterostructure as Photocatalyst for Organic Dye Removal.

A multicomponent composite membrane (P-S-T/C) with three-phase interface heterostructure is ingeniously designed. A polydopamine (PDA)-modified conductive carbon fiber cloth (CFC) is used as the substrate. Activated poly(vinylidene fluoride) (PVDF) with titanium dioxide (TiO2) and a silicon dioxide (SiO2) aerogel are electrospun as the top layer. The three-phase interface heterostructure was formed by TiO2, conductive CFC, and the SiO2 aerogel. Its photocatalytic performance is validated by photodegradation of organic dyes in a low-oxygen (O2) water environment. On combining with the capillary condensation of a bilayer structure, P-S-T/C exhibits excellent removal capability for anionic and cationic dyes. Moreover, P-S-T/C exhibits excellent stability and recyclability under simulated sunlight. The mechanism study indicates that the separated photogenerated carriers diffuse to the composite membrane surface rapidly on the three-phase interface of P-S-T/C. The abundant O2 adsorbed on the porous SiO2 aerogel surface acts as an electron (e–)-trapping agent, which can also decrease the work function of the composite materials. Superoxide radicals (•O2–) play a dominant role in the reaction of photodegradation supported by a free radical-trapping experiment. This work paves a way to design a membrane with photocatalytic performance by constructing the interface heterostructure.

Preparation and adsorption performance of functionalization cellulose-based composite aerogel

Herein, functionalization cellulose-based composite aerogels with the addition of carboxyl cellulose nanofibers (CNF), montmorillonite (MMT) and polyethyleneimine (PEI) were fabricated by solution blending and freeze-drying technology. MMT was blended into the cellulose framework as a reinforcing agent. PEI combined with cellulose through amidation reaction, and the synergism of hydrogen bond and chemical bond helped the CNF/MMT/PEI composite aerogels (CMP) with good mechanical properties. The morphology, chemical structure and thermal stability of the CMP were characterized. The adsorption properties and mechanism of the CMP were discussed, using Congo red (CR) dye as an adsorbate. The results showed that the CMP formed a three-dimensional network structure with abundant pores. The addition of PEI regulated the surface charge distribution of cellulose and improved the adsorption performance of CMP for CR with the adsorption capacity of 3114 mg/g calculated by the Langmuir model. The adsorption process of CMP-30 for CR was more in line with the pseudo-second-order kinetic model and Langmuir isotherm model, indicating chemical adsorption of a single molecular layer. After functionalized by octadecyl trichlorosilane (OTS), the contact angle of the aerogel surface was 151.80°. Meanwhile, the CMP-30 was transformed from hydrophilic and lipophilic properties to hydrophobic and lipophilic properties.

Silver-functionalized silica aerogel for iodine capture: Adsorbent aging by NO2 in spent nuclear fuel reprocessing off-gas

Silver-functionalized silica aerogel (Ag 0 -Aerogel) is considered a promising porous adsorbent for the capture of iodine from nuclear fuel reprocessing off-gas. The Ag 0 -Aerogel, nevertheless, experiences a steady loss of capacity when exposed to NO 2 in the off-gas. This phenomenon is known as aging and its governing processes remain unclear. We exposed Ag 0 -Aerogel samples to 2% NO 2 in dry air at 150 °C for up to 1 month, followed by I 2 loading. Samples were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Our results elucidated the precise Ag species in Ag 0 -Aerogel that adsorb I 2 : (i) Ag 0 nanoparticles, (ii) Ag thiolates (Ag–S-r) covering the nanoparticles and the aerogel backbone, and (iii) Ag–S complexes including amorphous Ag 2 S. We unraveled the two predominant underlying processes of aging in NO 2 : (i) Ag–S-r is oxidized by NO 2 forming silver sulfonate (Ag–SO 3 -r) which is oxidized further to silver sulfate (Ag 2 SO 4 ) molecules, (ii) Ag 2 SO 4 molecules then migrate from the pores to the aerogel surface and aggregate yielding Ag 2 SO 4 particles that do not adsorb I 2 . Plausible reaction pathways and aggregation mechanisms are explored. These findings may be used to guide the discovery of more advanced materials for iodine capture and the development of accurate predictive models. • The iodine capacity of Ag-aerogel is reduced by NO 2 at elevated temperatures. • Ag nanoparticles and Ag–S compounds coherently adsorb iodine. • NO 2 oxidizes Ag-thiolates forming Ag 2 SO 4 molecules that favor iodine adsorption. • Ag 2 SO 4 molecules migrate and accumulate on particles preventing iodine adsorption. • Thiolation step directly impacts Ag-aerogel aging in NO 2 .

Synthesis and adsorption properties of fibrous-like aerogel from acylhydrazone polyviologen: efficient removal of reactive dyes from wastewater

Adsorption of dyes on solid surfaces has been given considerable interest as one of the most efficient water treatment procedures owing to their low cost, simplicity, recyclability and adsorption efficiency. In this contribution, we report a simplified synthetic route of a novel bipyridinium-based viologen polymer from the polymerization of a viologen-based dialdehyde with aryl-based dihydrazide in an acidic aqueous solution. The developed polyviologen was exposed to the simple freeze-drying process to introduce the corresponding fibrous-like aerogel with high surface area. The chemical structure of the acylhydrazone-based viologen polymer (AHVP) was fully characterized using different spectroscopic techniques. AHVP displayed excellent affinity to form assembled hydrogel. Interestingly, the produced polymers introduced AHVP-linked covalent organic hydrogel framework that is organized in the form of nanofibers. Due to large surface area and surface functionalization, the ability of the active freeze-dried AHVP to adsorb Reactive Blue 19 (RB19) from an aqueous solution worth to be examined. Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), and UV–Vis absorption spectra were utilized to examine the aerogel surface morphology of the three-dimensional metal–organic viologen framework before and after adsorption of Reactive Blue 19.

Mesoporous and flexible polyimide aerogel as highly active catalytic membrane for AO7 degradation by peroxymonosulfate activation

• Mesoporous and flexible PI aerogel membrane is first selected as a PMS activator. • PI/PMS aerogel can efficiently remove AO7 without adsorption–desorption equilibrium. • PI/PMS aerogel membrane could keep high removal rate and permeation flux. • Non-radical pathway plays the dominant role for AO7 degradation. Driven by the organic contaminants in wastewater, peroxymonosulfate (PMS) as a source of reactive species has been developed, and metal-free catalysts have proven to be one kind of most promising PMS activators. In this work, mesoporous and flexible polyimide (PI) aerogel membrane with high specific surface area, expanded π-conjugated system and high strength is selected as one kind of PMS activator, and the PI/PMS aerogel system shows high organic contaminants degradation performance. Interestingly, the acid orange 7 (AO7) degradation rate constant of PI/PMS aerogel system without adsorption–desorption equilibrium stage is 2.5-fold faster than that of catalyst with adsorption–desorption equilibrium stage, because the adsorption of AO7 on PI aerogel covers the active sites of PI, and little PMS can be activated on the surface of PI aerogel. Notably, PI/PMS membrane system could remove 96.21% of AO7 with a slight decreased permeation flux for the twelfth cycle. Furthermore, the possible degradation mechanism was proposed, and radical quenching tests certified non-radical pathway played the dominant role for AO7 degradation. The successful application of PI aerogel membrane as PMS activator may shed light on designing new types of aerogel membrane for wastewater treatment.

Influence of drug properties on loadings and release kinetics of drugs from silica aerogels loaded in supercritical CO2

The present work investigates influence of drug properties on drug loadings in silica aerogels from supercritical carbon dioxide (scCO2) and their release. Benzoic acid (BA) and fenofibrate (FF) with different molecular mass and solubilities in water and scCO2 are selected as drugs for comparison of loadings by two modes: adsorption and adsorption plus precipitation, in pores and on outer surface of aerogels. Modeling of precipitation during depressurization predicts lower nucleation rates for FF due to its higher molecular mass and higher growth rates due to its higher supersaturation compared to BA. Higher drug solubility in scCO2 facilitates higher loadings by adsorption and precipitation. Experiments confirm that larger amounts of FF adsorb and precipitate compared to BA; precipitation occurs mostly on the outer surface of aerogels, in much shorter time than adsorption. The precipitated drugs are amorphous and release much faster than crystalline forms, though FF releases slower than BA.

Superhydrophobic and Multifunctional Aerogel Enabled by Bioinspired Salvinia Leaf‐Like Structure

AbstractThe biomimetic exploration of functionalized materials is still of great importance to chemists and materials scientists, although the majority of the ingenious structures and functions of organisms are not simulated precisely. Here, taking inspiration from the strongly hydrophobic properties of the Salvinia leaf, a novel superhydrophobic and multifunctional aramid‐polyimide nanocomposite aerogel with Salvinia leaf‐like structures is fabricated (abbreviated to Bio‐ANFPI aerogel). The Bio‐ANFPI‐1 aerogel surface is covered with many of the generated spherical and hemispherical silica nanoparticles by a in situ siloxane polycondensation method, analogous to the Salvinia leaf surface, which facilitates the construction of the superhydrophobic aerogels (Bio‐ANFPI‐2) based on the Cassie‐Baxter model. It is found that the maximum stress and compressive modulus of the Bio‐ANFPI‐2 aerogel are improved by 174% and 245%, respectively. Further, the Bio‐ANFPI‐2 aerogel exhibits superhydrophobicity, with a water contact angle of 152° and a rolling angle of 8.3°. In addition, the aerogels possess a low thermal conductivity, excellent metal ion absorption capacity, and impressive absorption capacity of oil that maintained its initial value at ≈80% after 50 cycles at 88% compression. Overall, this work can enable a more general and practical manner of fabricating biomimetic high‐performance lightweight materials.

A novel hydrophobic all-biomass aerogel reinforced by dialdehyde carboxymethyl cellulose for oil/organic solvent-water separation

We present a novel collagen-based hydrophobic aerogel for oil/water separation. The key feature of our approach is based on all-biomass materials, combined with effective crosslinking of collagen and dialdehyde carboxymethyl cellulose (DCMC) and hydrophobic coating by naturally derived waxes. The results show that the collagen with small amount of DCMC (∼0.25 wt%) under freezing and subsequent lyophilization can result in a spongy-like aerogel substrate with hierarchical structure and great reversible compressibility. The waxes coating not only maintains the interconnected porous structure, but also confers the micro/nano-scale wrinkling patterns on the resulting WC-Col aerogel surfaces. The hydrophobicity and lipophilicity of WC-Col aerogel is thus significantly improved as evidenced by a high contact angle of 144.4° and selective adsorption of oils from water. The repeated adsorption-squeezing tests demonstrate its reasonably good adsorption capacities and recyclability for varied oily liquids. Our study provides an ingenious approach to exploitation of biomass in pollutants removal.

ClO2-Loaded Aerogels with Biocide Effect.

In this work, the mechanism of chlorine dioxide's (ClO2) interaction with aerogel surfaces is described for the first time. To determine the mechanism, three types of aerogels (namely, silica, titania, and zirconia composites) were synthesized and characterized using N2 sorption isotherm analysis, X-ray diffraction analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The kinetics of the ClO2 interaction mechanism was investigated via ClO2-controlled sorption and desorption at different temperatures. The process was studied through the theoretical calculation of ClO2 interaction with the aerogel surface. The biocide efficiency of the as-synthesized ClO2-loaded aerogels on different bacteria strains was investigated, and efficient microorganism extermination was demonstrated. This system is a disinfectant that can find potential applications in various fields.

One-pot oxidative-adsorptive desulfurization of model and real fuel using micro-mesoporous SiO2 aerogel supported MoO3

In this research, micro-mesoporous SiO2 aerogel was used as support with different percentages of MoO3 and evaluated simultaneously as a catalyst for oxidation of dibenzothiophene (DBT) and as an adsorbent for oxidation products. Among studied weight percentages of MoO3, the SiO2 aerogel-supported catalyst with 1.5 wt% of MoO3 indicated the higher decline in C/C0 of DBT after 60 min (0.06). The characterization of the as-prepared catalysts by XRD, FESEM, EDX, FTIR, BET-BJH, and TEM indicated that MoO3 nanoparticles were uniformly dispersed on the surface of silica aerogel at all studied percentages. Despite a regular reduction in porosity with increasing MoO3 content, catalytic activity in DBT oxidation enhanced due to enhancing MoO3 content, amount of active sites, and hydrophilicity of surface for adsorbing H2O2, which is dissolved in water. Successive runs of oxidative-adsorptive desulfurization confirmed the stability of the MoO3–SiO2 aerogel catalyst. Examination of spent catalyst indicated that while crystalline structure remained unchanged, the porosity of spent catalyst decreased due to adsorption of DBT sulfones on the surface. In the following Iranian gasoil was subjected to the novel method of desulfurization and the GC-MS result indicated a noticeable reduction in sulfur-containing components of fuel after desulfurization.

Graphene aerogel supported Pt-Ni alloy as efficient electrocatalysts for alcohol fuel oxidation

Alcohol fuels oxidation plays a significant role in carbon sustainable cycling and high-performance catalyst with a strong anti-poisoning effect is desired. Herein, Pt-Ni alloy supported on the N-doped graphene aerogel synthesized by simple freeze-drying and annealing was demonstrated to have such catalytic ability for alcohol fuel oxidation. Pt-Ni alloy particles were found uniformly dispersed over the surface of 3D N-doped graphene aerogel. High anti-poisoning ability for CO-like intermediates oxidation was demonstrated by the CO-stripping experiment. The as-prepared catalyst was found to have outstanding catalytic performance for methanol and ethanol oxidation with high catalytic activity, stability and catalytic kinetics. Compared to the control samples, the improved catalytic ability could be due to the presence of oxophilic Ni species and the support effect of 3D N-doped graphene aerogel that combined multi-advantages of large surface area, facile mass transfer, and abundant defects.

Cattail fibers as source of cellulose to prepare a novel type of composite aerogel adsorbent for the removal of enrofloxacin in wastewater

In this study, cattail was researched as a natural cellulose source to extract cellulose. Dewaxing, alkali and bleaching treatments were carried out for the cattail fibers (CFs). The FTIR, SEM and XRD results indicated that hemicellulose and lignin were successfully removed from the CFs, and the content of cattail cellulose increased from 41.66 ± 1.11% to 89.72 ± 1.07%. Subsequently, cellulose aerogel was prepared by the extracted cattail cellulose. The Zeolitic imidazolate framework-8 (ZIF-8) was uniformly loaded onto the surface of cellulose aerogel by the in situ growth, and ZIF-8 Cattail Cellulose Aerogel (ZCCA) was finally prepared. The SEM, FTIR, XRD and TGA results further confirmed the successful preparation of ZCCA. Additionally, the results of the adsorption experiment showed that ZCCA had excellent adsorption performance for enrofloxacin, and the maximum adsorption capacity of enrofloxacin reached 172.09 mg·g−1 while showing good reusability. The adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic studies showed that the adsorption of enrofloxacin was a spontaneous endothermic reaction and that the adsorption mechanism involves the interaction of hydrogen bonds, electrostatic and π-π stacking.

The Importance of Precursors and Modification Groups of Aerogels in CO2 Capture.

The rapid growth of CO2 emissions in the atmosphere has attracted great attention due to the influence of the greenhouse effect. Aerogels’ application for capturing CO2 is quite promising owing to their numerous advantages, such as high porosity (~95%); these are predominantly mesoporous (20–50 nm) materials with very high surface area (>800 m2∙g−1). To increase the CO2 level of aerogels’ uptake capacity and selectivity, active materials have been investigated, such as potassium carbonate, K2CO3, amines, and ionic-liquid amino-acid moieties loaded onto the surface of aerogels. The flexibility of the composition and surface chemistry of aerogels can be modified intentionally—indeed, manipulated—for CO2 capture. Up to now, most research has focused mainly on the synthesis of amine-modified silica aerogels and the evaluation of their CO2-sorption properties. However, there is no comprehensive study focusing on the effect of different types of aerogels and modification groups on the adsorption of CO2. In this review, we present, in broad terms, the use of different precursors, as well as modification of synthesis parameters. The present review aims to consider which kind of precursors and modification groups can serve as potentially attractive molecular-design characteristics in promising materials for capturing CO2.

Spray coating of cellulose aerogel particles in a miniaturized spouted bed

Aim of this work is to apply protective and homogeneous shellac coating layers on the surface of hydrophilic open-pore cellulose aerogel particles with low densities ≤ 0.1 g/cm3 and high specific surface areas in the range of ~ 400–450 m2/g while keeping the aerogels’ microstructure intact during processing. For this purpose, an innovative miniaturized spouted bed setup was used. Successful process settings for application of enclosed films on aerogel surfaces without intrusion of coating material into the pores were determined. Precise control of coating layer thickness in the range of 10–50 µm was achieved due to variation of coating solution amount without agglomeration and clogging events occurring during processing. Comparison of bulk densities and specific surface areas before and after coating proved the intactness of the porous structure. Coating of particles loaded with vanillin led to controlled release, enhancing release half-life times from 20 to 1600 min. Overall, a successful strategy for coating of organic low-density aerogels was developed.