Xerogel Particles Research Articles

ВЛИЯНИЕ ДЛИТЕЛЬНОСТИ МЕХАНОХИМИЧЕСКОГО СИНТЕЗА НА СТРУКТУРНО-МОРФОЛОГИЧЕСКИЕ ХАРАКТЕРИСТИКИ СИЛИКАТ-КАЛЬЦИЕВОЙ ДИСПЕРСИИ

Mechanochemical synthesis of sucrose-modified calcium hydrosilicates as precursors of calcium silicate dispersions – polyfunctional additives for cement systems was carried out on a fine grinding vibromill VM-20. The influence of duration of mechanochemical synthesis of modified hydrosilicates on the phase composition of calcium silicate dispersions, morpho-structural characteristics of the nanostructured calcium silicate xerogel particles, as well as technological features of the reaction mass of mechanochemical synthesis was studied. It was found that the viscosity of the reaction mass of mechanochemical synthesis changes non-monotonically during synthesis: in the first 2 hours of mechanochemical synthesis, the viscosity decreases; subsequently, the viscosity of the mixture increases slightly; the reaction mass maintains high fluidity throughout the entire synthesis process; the presence of raw mineral materials in the reaction mass continues to be fixed throughout the synthesis (up to 7 hours); recrystallization processes of synthesized weakly crystallized phases are activated after 6 hours of grinding.
 The volume of the synthesized xerogel was estimated from the specific surface area of the calcium silicate dispersion. It was found that the processes of recrystallization of weakly crystallized phases synthesized during mechanochemical synthesis do not affect the volume of xerogel in the composition of calcium silicate dispersion, the specific surface area of the calcium silicate dispersion increases in proportion to the duration of the mechanochemical synthesis of modified calcium hydrosilicates. The duration of mechanochemical synthesis does not affect the morpho-structural characteristics of coagulation xerogel particles.

Structure and Properties of the Xerogels Based on Potassium Silicate Liquid Glass and Urea.

The xerogels based on the aqueous solutions of urea in potassium silicate liquid glass (PSLG) were produced by CO2 bubbling and investigated. The structure and chemical composition of the obtained materials were analyzed. Using the SEM, XRD, IR-FT, DSC, and low energy local EDS analysis, it was recognized that the dried gels (xerogels) contained three forms of urea: oval crystals of regular shape appeared onto the surface of xerogel particles; fibrous crystals were located in the silicate matrix; and molecules/ions were incorporated into the silicate matrix. It was shown that an increase in [(NH2)2CO] in the gel-forming system promoted increased contents in crystalline forms of urea as well as the diameter of the fiber-shaped urea crystals. A rate of the urea release in water from the granulated xerogels containing 5.8, 12.6, and 17.9 wt.% of urea was determined by the photometric method. It was determined that the obtained urea-containing xerogels were characterized with a slow release of urea, which continued up to 120 days, and could be used as controlled release fertilizers containing useful nutrients (N, K).

5Y–ZrO2 NPs with high dispersity and excellent sintering performance prepared by a novel sol-gel-flux method in the NaCl system

Herein, to alleviate the hard agglomeration of ZrO2 nanoparticles (NPs) fabricated by the traditional sol-gel method (SGM), a novel sol-gel-flux method (SGFM) is applied to tailor ZrO2 nanoparticles (NPs) stabilized by 5 mol% Y2O3 (5Y–ZrO2) by in situ introduction of NaCl NPs among xerogel particles. The phase composition, micromorphology, surface area, and sintering performances of 5Y–ZrO2 products fabricated by SGM and SGFM are compared. The effects of calcination temperature on the phase composition, micromorphology, and particle size of 5Y–ZrO2 products prepared by SGFM are systematically investigated. The results show that the 5Y–ZrO2 particles prepared by SGM are severely agglomerated and irregular, while the 5Y–ZrO2 NPs prepared by SGFM are well dispersed, uniformly distributed, and quasispherical. The former can hardly be densified by sintering, while the latter shows excellent sintering performance. By sintering 5Y–ZrO2 NPs prepared by SGFM at 1200 °C for 3 h, 5Y-TZP with a high density and an average grain size of 0.29 μm is fabricated. The in situ generated NaCl particles effectively separate ZrO2 particles during sintering. The calcination temperature plays a crucial role in controlling the phase composition, agglomeration degree, micromorphology, particle size distribution, and particle size of 5Y–ZrO2 products synthesized by SGFM, and the optimal calcination temperature is suggested to be 790 °C.

Rotating disk electrode measurements on low and high loading catalyst layers: Diffusion limitations and application to Pt catalysts supported on porous micrometric carbon xerogel particles designed for proton exchange membrane fuel cells

Innovative fuel cell catalysts are now often being supported on nanostructured materials in order to improve mass transport, contact with the ionomer and active phase distribution. However, to maintain their inner structure, these supports are used as µm-sized particles, which hampers to perform accurate kinetic experiments on rotating disk electrode since a thin layer of catalyst is in principle required. The present study thus aims at checking if accurate measurements remain possible for thick layers of large particles. To do so, oxygen reduction was first performed on a commercial Pt catalyst supported on carbon black; both a typical thin and a thick layer (37 and 370 µgPt cm−2) were used. The impact of the diffusion limitations on the kinetic current was determined. The same measurement protocol was then performed with a catalyst supported on 5 µm particles of a nanostructured carbon (∼15 µm layer thickness, 370 µgPt cm−2). Results and calculation show that, for both thick layers, the kinetic current should be measured at higher potential (1.00 or 1.05 V/ESH) than usual to avoid diffusion limitations. Also, the voltage scanning rate should be lowered to 0.5 or 1 mV s−1 to decrease the impact of the double layer capacity on the measurements.

Stainless Steel Screen Modified with Renatured Xerogel for Efficient and Highly Stable Oil/Water Separation via Gravity.

The application of hydrogel coatings to surface-modified metallic materials has gained considerable attention in engineering practice such as water-oil separation. However, the low coating adhesion and poor coating stability restrict its application. In this study, to obtain special wettability and durable filter materials, polyacrylamide (PAM)/sodium alginate (SA) xerogel particles were first prepared and adhered to a stainless steel screen by using an epoxy resin as a linker. Subsequently, the xerogel particles of the screen rehydrates in water to form a PAM-SA double-network hydrogel. The results show that the screen modified by PAM-SA xerogel of 20-30 μm particle size and a linker concentration of 0.1 g/mL resulted in a chimeric structure and subsequently transformed a uniform double-network hydrogel coating in water. According to the experimental results, the rough hydrogel coating exhibits superhydrophilicity and superoleophobicity under water; in particular, it has excellent wear resistance as well as physical and chemical stability. Under gravity-driven action, the PAM-SA-modified screen demonstrates high separation efficiency values of up to 99% in separating a wide range of oil/water mixtures and maintaining a water flux of (2-6) × 104 L·m-2·h-1. There was no significant reduction in efficiency of separation and water flux after 10 cycles, indicating that the PAM-SA-modified screen is capable of offering outstanding separation performance and durability. Moreover, the hydrogel-modified screen demonstrated corrosion and swelling resistance in some extreme environments, paving a way for practical applications in water treatment. The novel hydrogel-coating-modified screen with ease of preparation holds great promise for oil/water separation and other engineering applications.

Relationship among the composition, synthesis conditions, and surface acid-basic properties of xerogel particles based on zirconium dioxide

ZrO2–Y2O3–CeO2, ZrO2–Y2O3 and ZrO2–CeO2 xerogels were prepared by coprecipitation of the corresponding hydroxides followed by the precipitate processing using different procedures involving maturation in the mother liquor within 24 h, freezing and ultrasonic treatment. The surface acid-base properties of the prepared xerogel particles were studied by measuring pH changes upon their suspension in water. The obtained results allow the analysis of relationships among the xerogel synthesis conditions, behavior of xerogel particles in the aqueous medium and their agglomeration, thus providing the adjustment and prediction of the properties of ceramic materials prepared from the studied powders.

Hierarchically porous metal hydroxide/metal–organic framework composite nanoarchitectures as broad-spectrum adsorbents for toxic chemical filtration

We demonstrate that the hierarchically porous metal hydroxide/metal–organic framework composite nanoarchitectures exhibit broad-spectrum removal activity for three chemically distinct toxic gases, viz. acid gases, base gases, and nitrogen oxides. A facile and general in-situ hydrolysis strategy combined with gentle ambient pressure drying (APD) was utilized to integrate both Zr(OH)4 and Ti(OH)4 with the amino-functionalized MOF-808 xerogel (G808-NH2). The M(OH)4/G808-NH2 xerogel composites manifested 3D crystalline porous networks and substantially hierarchical porosity, with controllable amounts of amorphous M(OH)4 nanoparticles residing at the edge of xerogel particles. Microbreakthrough tests were performed under both dry and moist conditions to evaluate the filtration capabilities of the composites against three representative compounds: SO2, NH3, and NO2. Compared with the pristine G808-NH2 xerogel, the incorporation of M(OH)4 effectively enhanced the broad-spectrum toxic chemical mitigation ability of the material, with the highest SO2, NH3, and NO2 breakthrough uptake reaching 74.5, 55.3, and 394.0 mg/g, respectively. Post-breakthrough characterization confirmed the abundant M-OH groups with diverse binding configurations, alongside the unsaturated M (IV) centers on the surface of M(OH)4 provided extra adsorption sites for irreversible toxic chemical capture besides Van der Waals driven physisorption. The ability to achieve high-capacity adsorption and strong retention for multiple contaminants is of great significance for real-world filtration applications.

Long-lasting adsorption of golden flower oil on polyvinyl alcohol/clinoptilolite (PVA/CP) xerogel particles

The present work aimed to study the adsorption and desorption characteristics of Golden Flower Oil (GFO) on xerogel particles made of Clinoptilolite (CP), a natural zeolite and polyvinyl alcohol (PVA). Firstly, chemical composition and physical characteristics of GFO (by GC/MS) and CP (by SEM and BET) were thoroughly characterized. PVA/CP xerogel was synthesized then and characterized by SEM, BET, TGA, and DSC techniques. Adsorption of the 12 GFO components on the CP and PVA/CP xerogel surface was investigated in different concentrations of GFO components. Both adsorbents showed concentration-independent and selective adsorption for GFO components. The selective adsorption index showed a direct relationship with polarity (δP) of the components and inversely correlated with their molar volume (Vm). Adsorption isotherms of the components were fitted by Langmuir, Freundlich, and Temkin equations. Maximum monolayer GFO adsorption on PVA/CP surface was equal to 231.93 mg g−1 compared to 198.73 mg g−1 for CP as an adsorbent. The maximum desorbed amount for each of the components was directly related to the Vm parameter and the weight percentage of each GFO component in the oil and inversely related to δP. Multilayer desorbed amount from PVA/CP xerogel particles (366.03 mg g−1) was less than that for CP particles (573.36 mg g−1) supporting PVA/CP for retaining GFO for longer periods.

Preparation and characterization of nano-sized silica xerogel particles using sodium silicate solution extracted from waste container glasses

In this work, nano-sized silica xerogel particles were synthesized using sodium silicate solution prepared from waste container glasses (of mix colors) as precursor. The as-received waste container glasses of different mix colors (green, white and amber) from municipal dumpsite were initially washed, crushed and wet milled for 24 h then sieved through 63 μm mesh. The sieved glass slurries were then oven dried at 110 °C for 72 h to obtain powdered glass (GP). Appropriate amount of GP was reacted with 320 ml of 3 M NaOH solutions respectively in a 500 ml Erlenmeyer flask placed on a hot plate connected with a reflux condenser and continuously stirred at 40 rpm with the aid of magnetic stirrer for a period of 3 h under reaction temperature of 200 °C. The resultant solution was filtered to obtain sodium silicate solutions (SSS). 3 M HCl was prepared and was gently added into the SSS whilst continuously stirred to obtain a white gelly-like mixture (at pH ˂10). The gelly mixture was left for 18 h (ageing), then filtered and dried in an electric oven at 80 °C for 12 h to obtain highly pure silica gel particles and then characterized. The results showed that the synthesized nano-sized silica particles range between 0.031 (31 nm) μm to 0.051 (51 nm) μm.

Hybrid Ionic Liquid–Silica Xerogels Applied in CO2 Capture

The imidazolium-based ionic liquids (ILs) are solvents known for selectively solubilizing CO2 from a gas CH4/CO2 mixture, hence we have produced new hybrid adsorbents by immobilizing two ILs on xerogel silica to obtain a solid–gas system that benefits the ILs’ properties and can be industrially applied in CO2 capture. In this work, the ILs (MeO)3Sipmim.Cl and (MeO)3Sipmim.Tf2N were used at different loadings via the sol–gel process employing a based 1-methyl-3-(3-trimethoxysylilpropyl) imidazolium IL associated to the anion Cl− or Tf2N− as a reactant in the synthesis of silica xerogel. The CO2 adsorption measurements were conducted through pressure and temperature gravimetric analysis (PTGA) using a microbalance. SEM microscopies images have shown that there is an IL limit concentration that can be immobilized (ca. 20%) and that the xerogel particles have a spherical shape with an average size of 20 µm. The adsorbent with 20% IL (MeO)3Sipmim.Cl, SILCLX20, shows greater capacity to absorb CO2, reaching a value of 0.35 g CO2 / g adsorbent at 0.1 MPa (298 K). Surprisingly, the result for xerogel with IL (MeO)3Sipmim.Tf2N shows poor performance, with only 0.05 g CO2 / g absorbed, even having a hydrophobic character which would benefit their interaction with CO2. However, this hydrophobicity could interfere negatively in the xerogel synthesis process. The immobilization of ionic liquids in silica xerogel is an advantageous technique that reduces costs in the use of ILs as they can be used in smaller quantities and can be recycled after CO2 desorption.

Effect of processing parameters and pore structure of nanostructured silica aerogel on the physical properties of aerogel blankets

This work investigates the influence of processing parameters and aerogel pore structure on the physical properties and hydrophobicity of aerogel blankets. Aerogel blankets were produced by in situ synthesis of nanostructured silica aerogel on a polyester nonwoven substrate. Nitrogen adsorption-desorption analysis, contact angle test and FE-SEM images were used to characterize both the aerogel particles and the blankets. The results showed that the weight and thickness of the blanket were reduced when the low amount of catalyst was used. A decrease in the aerogel pore size from 22 to 11 nm increased the weight and thickness of the blankets. The xerogel particles with high density and pore size of 5 nm reduced the blanket weight. Also, the blanket weight and thickness were increased due to increasing the sol volume. It was found that the hydrophobicity of aerogel blankets is not influenced by sol volume and pore structure of silica aerogel.

Aerosol-assisted synthesis of submicron particles at room temperature using ultra-fine liquid atomization

Aerosol-assisted particle technologies are common in commercial atomizing devices for producing micron-sized droplets, which upon evaporation of solvent typically yield particles in the micron to submicron range obtained from a process of droplet-to-particle conversion. In this paper, we demonstrate a technology that allows room-temperature manufacturing of particles O(100–500) nm in diameter by generating and drying of submicron droplet aerosols. As measured for water atomization, the produced droplets of O(200) nm in mean diameter are an order of magnitude smaller than 3–5 µm water droplets usually obtained from commercial atomizers and nebulizers. This reduction in droplet size promotes evaporation of solvent around two orders of magnitude faster than for the droplets produced by conventional atomization devices. Such rapid solvent evaporation enables formation of submicron particles even in the limit of room temperature drying conditions in a compact laboratory-scale setup, as we demonstrate in this study for sodium chloride and silica and titania xerogel particles. Ultra-fine diameters of the generated droplets enable the usage of more concentrated precursor solutions, e.g. ten or even one hundred times, to obtain the same final particle size as conventional aerosol-assisted setups. Based on the experimental study, we establish mathematical expressions correlating the mean particle size and production capacity with solute concentration in the precursor, physical properties of the solution and the atomizing air pressure. Finally, we compare and demonstrate the advantages of the developed system over the existing aerosol-assisted processes in terms of smaller particle size, larger overall and specific production capacities, and higher estimated energy efficiency. The results suggest that this economical and scalable method can be utilized for aerosol-assisted submicron particle synthesis in different applications.

Structural and electrosurface characteristics of titanium dioxide xerogel prepared by the sol–gel method

Stable highly concentrated TiO2 sol has been synthesized using binary titanyl ammonium sulfate monohydrate, (NH4)2TiO(SO4)2 · H2O. Treatment of the sol with an ammonia solution has yielded a stable hydrogel, which, after being dried, is transformed into a TiO2 xerogel. Study of the structure-related sorption and crystalline-chemical properties of the synthesized xerogel has shown that it represents a semicrystalline micro/mesoporous material with a rather developed specific surface area (Ssp = 120 m2/g). According to potentiometric titration data, the point of zero charge (PZC) of this material is located at pH 3.9. Measurements of the electrophoretic mobility (by microelectrophoresis) of TiO2 xerogel particles in solutions of HCl, NaOH, and salts of mono-, bi-, and trivalent cations have shown that (1) the isoelectric point (IEP) of the particles lies in the vicinity of pH 6.2, i.e., at a much higher pH than that for PZC; (2) the presence of increasing amounts of 1: 1 and 2: 1 electrolytes causes a gradual and a dramatic reduction in the ζ potential of the particles, respectively; and (3), in the presence of an electrolyte with a trivalent counterion, the surface charge is reversed. The behavior of TiO2 xerogel in an electric field is similar to that of lyophobic particles, with the difference that there is no maximum in the ζ potential versus 1: 1 electrolyte concentration dependence and the measured IEP of the xerogel is much higher than its PZC. Possible reasons for this discrepancy have been discussed.

Ultrasonic preparation of mesoporous silica using pyridinium ionic liquid

Mesoporous silica matrices have been prepared via classic acid catalyzed and sono-catalyzed sol-gel routes. Tetramethoxysilan (TMOS) and methyl-trimethoxysilane (MTMS) were used as silica precursors, and N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]) was employed as co-solvent and pore template. The ionic liquid (IL) to silica mole ratio was varied between 0.007 and 0.07. Nitrogen adsorption-desorption and small-angle neutron scattering measurements were used to characterize the obtained materials. The ionic liquid played the role of catalyst that affected the formation of the primary xerogel particles, and changed the porosity of the materials. Ultrasound treatment resulted in microstructure change on the level of the colloid particle aggregates. In comparison with IL containing xerogels, the IL containing sonogels show increased pore diameter, bigger pore volumes and diminished surface areas.

Sol–Gel Preparation of Samaria Catalysts for the Oxidative Coupling of Methane

A new sol–gel synthesis route for alumina–samaria mixed aero- and xerogel catalysts based on the so-called epoxide addition method and the use of these systems as catalysts for the oxidative coupling of methane (OCM) is reported. As precursors simple chloride or nitrate salts can be used. The mesoporous materials are X-ray amorphous even after calcination to 800 °C and show an intimate mixing of Al and Sm on the nanoscale. In the case of the xerogels derived from chlorides, C2 yields comparable to pure samaria can be achieved under OCM reaction conditions with 100 % O2 conversion. Even at lower O2 conversions the activity of the xerogel is competitive with a pure samaria reference catalyst taking the lower samaria content of 20 % into account. Accordingly, the approach is suitable to reduce the costs associated with the rare earth oxide. In addition to the preparation of aerogel and xerogel particles, the presented synthesis also allows the fabrication of xerogel films which can be coated on a suitable (monolithic) support. First results of such films are presented.

Formulation and characterization of ORMOSIL particles loaded with budesonide for local colonic delivery

In this study, hybrid silica xerogel particles were developed as carriers of budesonide (BDS) for efficient local treatment of inflammatory bowel diseases (IBD). Organically modified silica particles (ORMOSILs) were prepared by co-condensation of 3-aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) by an ambient temperature acid catalysed sol–gel process followed by spray-drying. Formulation for preparation of BDS-loaded particles was optimized and their physicochemical parameters and drug release profiles were evaluated in vitro. Optimal formulation had a small particle size (mean diameter of 1.45±0.02μm) with unimodal narrow size distribution and high encapsulation efficiency (98.0±1.85%). Due to the positive surface charge originated from amino group of APTES, ORMOSILs showed excessive mucoadhesiveness in comparison to native TEOS particles. The drug release decreased with increasing pH from 2.0 to 7.4. In order to avoid undesirable erroneous performance in the upper GI tract, particles were additionally coated with Eudragit® FS 30D, as a barrier to the drug release at pH range from 2.0 to 7.0. After Eudragit® FS 30D coating, the release of BDS in acidic media was sustained, while no significant differences in drug release were observed at pH 7.4. In conclusion, pH-responsive ORMOSILs showed great potential for efficient BDS delivery to the colon region.

One-step synthesis and effect of heat-treatment on the structure and electrochemical properties of LiNi0.5Mn1.5O4 cathode material for lithium-ion batteries

Spinel LiNi0.5Mn1.5O4 (Fd-3m) powders are synthesized by a facile one-step sol-gel approach with a resorcinol formaldehyde (RF) resin as a chelating agent. The cross-linked metal-containing RF xerogel particles are sintered at different high temperatures from 750 to 950°C to produce several micron-sized LiNi0.5Mn1.5O4 powders. Electrochemical measurements suggest that the 850°C-sintered (in air) sample (Fd-3m phase) performs the best with a discharge capacity of 141 mAh g−1 at 0.1C and 110 mAh g−1 at 10C, and capacity-retention of 96.3% after 60 cycles at 0.25C and 89% after 200 cycles at 1C. For comparison, the LiNi0.5Mn1.5O4 sample sintered at 850°C in O2 (P4332 phase) presents limited rate performance (45 mAh g−1 at 10C) and higher values in both AC impedance and DC-method derived resistance. A characteristic double “w”-shape curve of DC resistance against cell potential can be possibly considered as an indicator to probe the material structure transition during the charge/discharge process of the cell.

Microwave firing-incubation of cage-like (Ba, Sr)3MgSi2O8:0.06Eu2+,0.1Mn2+ sphere from sprayed template-free xerogel particles

Morphology control of cage-like (Ba, Sr)3MgSi2O8: Eu, Mn luminous sphere in micrometer size with a simultaneous 660 nm/430 nm-featured band emission was investigated via microwave (MW) firing procedure. A firing temperature range associated with distinct reaction of xerogel particles was determined by thermal analysis, at which the pure host phase of (Ba, Sr)3MgSi2O8 was formed and the release of decomposed gas from the precipitated nitrates played a key role in controlling the multi-scale structured morphology. As-prepared Ba1.14Sr1.7MgSi2O8:0.06Eu2+,0.1Mn2+ samples featured in a band emission simultaneously emitting at both 660 and 430 nm under 350 nm light excitation by MW procedure with an enhancement emission compared to the sample by solid state procedure. The results suggested that MW firing procedure affected assembling cage-like particle in meso-, nano- and submicro- meters to achieve photoluminescence (PL) enhancement of the simultaneous red/blue emission.

Polysulfone mixed matrix gas separation hollow fibre membranes filled with polymer and carbon xerogels

This work involves the preparation, tensile testing and gas separation characterization of polysulfone mixed matrix hollow fibres filled with polymeric sol based, and subsequently carbonised, xerogels. The pore characteristics of the xerogels were determined using a surface area and porosity analyser. The xerogel materials were reduced to submicron particles by grinding and wet milling, and the resultant particle size was determined using dynamic light scattering. Using dry/wet forced convection spinning, mixed matrix hollow fibre membranes (MMMs) were spun from solutions of polysulfone loaded with the submicron xerogel particles. At 5% loading, all MMMs exhibited higher strain at break and higher strength than unfilled membranes. Compared to unfilled fibres, MMMs were stiffer when filled with hard xerogel inclusions but became more pliable when filled with soft xerogel particles. Knudsen diffusion becomes an important gas transport mechanism in the membranes filled with mesoporous xerogels. When compared to the unfilled hollow fibres, these membranes showed a strong increase in the permeation of low molecular weight, high kinetic diameter gases, leading to a decline in fast/slow gas selectivities. All types of MMM gave higher CO2/O2 (fast/fast) and CH4/N2 (slow/slow) selectivities than unfilled hollow fibres. The MMMs filled with a microporous xerogel gave a higher CO2 pressure normalized flux when compared to the unfilled fibres without sacrificing the CO2/CH4 selectivity. Future work should focus on the tailoring of the pore size of the xerogels and on the wet milling procedure to obtain smaller filler particles.

Relationship Between Structural Properties and Electrochemical Characteristics of Monolithic Carbon Xerogel‐Based Electrochemical Double‐Layer Electrodes in Aqueous and Organic Electrolytes

AbstractThe impact of the micropore width, external surface area, and meso‐/macropore size on the charging performance of electrochemical double‐layer capacitor (EDLC) electrodes is systematically investigated. Nonactivated carbon xerogels are used as model electrodes in aqueous and organic electrolytes. Monolithic porous model carbons with different structural parameters are prepared using a resorcinol‐formaldehyde‐based sol–gel process and subsequent pyrolysis of the organic precursors. Electrochemical properties are characterized by utilizing them as EDLC half‐cells operated in aqueous and organic electrolytes, respectively. Experimental data derived for organic electrolytes reveals that the respective ions cannot enter the micropores within the skeleton of the meso‐ and macroporous carbons. Therefore the total capacitance is limited by the external surface formed by the interface between the meso‐/macropores and the microporous carbon particles forming the xerogel skeleton. In contrast, for aqueous electrolytes the total capacitance solely depends on the total surface area, including interfaces at the micropore scale. For both types of electrolytes the charging rate of the electrodes is systematically enhanced when increasing the diameter of the carbon xerogel particles from 10 to 75 nm and the meso‐/macropore size from 10 to 121 nm.