Mesoporous Carbonaceous Materials Research Articles

Naphthenic acids removal using N-doped hemp fibers based mesoporous carbon from aqueous waste stream

There is a substantial need for removing the contaminants from aqueous waste stream using affordable, stable, and active adsorbents, such as heteroatom-doped carbonaceous materials. Heteroatom such as N-doped carbonaceous materials greatly improve the performance of carbon materials by enhancing their conductivity, basicity, oxidation stability, catalytic activity and adsorption capacity. In this study, hemp fibers (HFs) and N-aminoguanidine were utilized as carbon and nitrogen precursors to synthesize N-functionalized mesoporous carbon materials (N-HFCs) via simultaneous activation and carbonization with ZnCl2. Higher BET surface area with a distinctive mesoporous structure and the covalent bond between N and C was developed in the prepared carbon, making N-HFCs suitable for adsorbing naphthenic acids (2-naphthoic acid and benzoic acid) from aqueous waste streams. Developed covalent bond helps to prevent the leaching of carbonaceous materials during adsorption study. The results showed that N-HFC-2 (ZnCl2: N-HFs ratio = 2:1) exhibited a higher removal efficiency of naphthenic acids (2-naphthoic acid and benzoic acid) compared to nonfunctionalized porous carbon (HFC). Adsorption of 2-naphthoic acid and benzoic acid on the adsorbents followed the typical monolayer type of Langmuir adsorption model. The maximum adsorption capacity of HFC after 48 h was evaluated as 70 and 27 mg/g for 2-naphthoic acid and benzoic acid. Likewise, the maximum adsorption capacity of N-HFC-2 for 2-naphthoic acid and benzoic acid was found to be 71 and 33 mg/g. In the adsorption kinetic experiment, adsorption of 2-naphthoic acid and benzoic acid reached equilibrium within 1 h using both the adsorbents (N-HFC-2 and HFC). Adsorption kinetics were analyzed using pseudo-first-order and pseudo-second-order kinetic models and were found to follow a pseudo-second-order kinetic model. Although changing pH from 4.4 to 8.5 did not have any significant effect on the removal efficiency of 2-napthoic acid using HFC and N-HFC-2, the removal efficiency of benzoic acid was decreased from 94 to 60 % using HFC and increased from 98 to 100 % using N-HFC-2. Comparative evaluations demonstrated that the mesoporous carbonaceous materials derived from HFs are an attractive adsorbent for removal of such contaminants from contaminated aqueous streams.

Multifunctional Mesoporous Carbonaceous Materials Enable the High Performance of Lithium-Sulfur Batteries.

Focusing on multifunctional mesoporous carbonaceous materials (MCMs) is one of the hot research topics due to increasing demand in the high-energy-density devices of lithium-sulfur (Li-S) batteries (2600 Wh kg-1). On the premise of applying MCMs as a porous framework to load elemental sulfur, to improve the electronic conductivity of the cathode, and to trap the in situ-formed electrolyte-soluble intermediates of lithium polysulfides (LiPSs), the commercialization of MCMs-based energy storage devices still needs to solve solid/solid and solid/liquid interfacial issues such as the chemical anchoring of the electrically insulating active substances, the sluggish redox kinetics of intermediate LiPSs, and so on. Through the permutation of multifunctional MCMs serving as the primary sulfur-loading carrier of the cathode, as the secondary surface-coating layers of the separator, the cathode, and the anode separately, this Perspective highlights research challenges to clarify a comprehensive high-performance mechanism of MCM-based Li-S batteries and provides new chemical insight for potential application purposes.

Evaluation of the Isomerization of α-Pinene Epoxide to Campholenic Aldehyde Using a Catalyst Obtained from Orange Peels (Citrus sinensis)

Orange peels (Citrus sinensis) are an abundant lignocellulosic residue that can be used as a carbon source to obtain solids with catalytic potential in the transformation of terpenes and their oxides into value-added products. This research seeks to evaluate the isomerization of α-pinene epoxide to campholenic aldehyde using a catalyst obtained from orange peels. The material OAC-Zn was obtained by activation of orange peel with ZnSO4.7H2O followed by thermal treatment at 500 °C; an additional solid was obtained from orange peel by pyrolysis at 500 °C (OC-500). XRD revealed the presence of ZnO and ZnS in OAC-Zn; TGA analysis indicated thermal stability in OAC-Zn and OC-500 materials; SEM images showed porous surfaces of different morphology, and the presence of microporosity in OC-500 and mesoporosity in the OAC-Zn that was confirmed by physical nitrogen adsorption. The elements C, O, Zn and S was identified in OAC-Zn by EDX analysis. The results of TPD-NH3 showed that the solids contained medium and weak acidity. Campholenic aldehyde was synthesized with a 96 % selectivity over a mesoporous carbonaceous material obtained from orange peels using ZnSO4.7H2O as activating agent

Highly Efficient Mesoporous Carbonaceous CeO2 Catalyst for Dephosphorylation.

Phosphorus is fast becoming a critical element, as the global supply and demand are reaching unsustainable levels. Herein, the synthesis, characterization, and applicability of a novel biomass-derived mesoporous carbonaceous material decorated with CeO2 (CeO2-S400) as an efficient catalyst for the dephosphorylation of 4-nitrophenyl phosphate disodium salt hexahydrate are reported. The presence and distribution of CeO2 are evidenced by inductively coupled plasma mass spectrometry (ICP-MS) (118.7 mg/g), high-resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray (EDX) mapping. The apparent rate constant for the efficient catalysis of 4-nitrophenyl phosphate disodium salt hexahydrate was 0.097 ± 0.01 for CeO2-ES and 0.15 ± 0.03 min–1 for CeO2-S400, which followed first-order kinetics. Rate constants normalized by the catalytic loading (km) were 80.84 and 15.00 g–1 min–1 for CeO2-ES and CeO2-S400, respectively, and the normalized rate constants with respect to surface area were 3.38 and 0.04 m–2 min–1 for CeO2-ES and CeO2-S400, respectively. This indicates that the presence of CeO2 nanoparticles has a catalytic effect on the dephosphorylation reaction.

Nanoengineering of N-doped Mesoporous Carbon Nanoparticles with Adjustable Internal Cavities via Emulsion-Induced Assembly.

The preparation of mesoporous carbonaceous materials with particularly adjustable morphology is currently a hot area of research in mesoporous materials. Herein, a novel approach is reported for the construction of N-doped multicavity mesoporous carbon nanoparticles (NMMCNs) based on the “emulsion swelling–acid curing mechanism” using a nanoemulsion assembly method under a high-speed shearing force. Intriguingly, this approach adopted a novel acid (HCl) curing procedure. Impressively, the morphology evolution from an internal multicavity to a single cavity and then to a non-cavity interior structure could be accomplished by simply varying the synthesis parameters. Additionally, this synthesis approach ingeniously overcame the following problems: (i) technically, the employment of high temperatures and high pressures in traditional hydrothermal reaction curing environments is avoided; (ii) this approach removes the requirement for silicon coating, which provides a limited pyrolysis condition, to obtain a multi-chamber structure. Resveratrol (Res) is an insoluble natural medicine and was successfully loaded into NMMCNs, thereby the Res–NMMCNs delivery system was constructed. Importantly, the Res–NMMCNs delivery system could still retain the antitumor and antioxidant activity of Res in vitro.

Mesoporous Carbon Production by Nanocasting Technique Using Boehmite as a Template

A series of mesoporous carbonaceous materials were synthesized by the nanocasting technique using boehmite as a template and glucose as a carbon precursor. After pyrolysis and template removal, the resulting material is a mesoporous carbon that can be additionally doped with N, B and K during prepyrolysis impregnation. In addition, the influence of doping on the morphology, crystallinity and stability of the synthesized carbons was studied using X-ray diffraction, nitrogen physisorption, thermogravimetry, Raman and IR spectroscopy and transmission electron microscopy. While the nanocasting process is effective for the formation of mesopores, KOH and urea do not modify the textural properties of carbon. The use of H3PO4 as a dopant, however, led to the formation of an AlPO4 compound and resulted in a solid with a lower specific surface area and higher microporosity. All doped solids present higher thermal stability as a positive effect of the introduction of heteroatoms to the carbon skeleton. The phosphorus-doped sample has better oxidation resistance, with a combustion temperature 120–150 °C higher than those observed for the other materials.

Facile preparation protocol of magnetic mesoporous carbon acid catalysts via soft-template self-assembly method and their applications in conversion of xylose into furfural.

Furfural is a valuable dehydration product of xylose. It has a broad spectrum of industrial applications. Various catalysts containing SO3H have been reported for the conversion of xylose into furfural. Nevertheless, the multi-step preparation is tedious, and the catalysts are usually fine powders that are difficult to separate from the suspension. Novel magnetic mesoporous carbonaceous materials (Fe/MC) were successfully prepared via facile self-assembly in a single step. A facile subsequent hydrothermal sulfonation of Fe/MC with concentrated H2SO4 at 180°C gave mesoporous carbon bearing SO3H groups (SO3H@Fe/MC) without loss of the magnetic properties. Various techniques were employed to characterize the SO3H@Fe/MC as a candidate catalyst. It showed strong magnetism due to its Fe particles and possessed a 243 m2 g-1 BET-specific surface area and a 90% mesopore volume. The sample contained 0.21 mmol g-1 of SO3H and gave a high conversion and an acceptable furfural yield and selectivity (100%, 45% and 45%, respectively) when used at 170°C for 1 h with γ-valerolactone as solvent. The catalyst was easily separated after the catalytic tests by using a magnet, confirming sufficient magneticstability. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.

Twin-fold new methodology arising from microwave induced carbonization of newspaper waste for the adsorptive desulfurization of model oil

The removal of sulfur from diesel is an important concern. In this context, it is vital to explore the potential of low-cost adsorbents for desulfurization. In the present study, a mesoporous carbonaceous material was produced from the newspaper waste and utilized in the removal of Dibenzothiophene (DBT) through adsorptive desulfurization. The microwave-assisted mesoporous carbon fostered π interaction with DBT molecules and augmented the adsorptive desulfurization. The synthesized mesoporous carbon is endowed with good textural properties, porosity and uniformly distributed active sites. The characterization techniques such as SEM-EDX, FT-IR, XRF, XPS and pore size measurements ascertained the desulfurization and the adsorption process gave best fit for Langmuir adsorption isotherm model following the pseudo-second-order kinetics. The regeneration studies ascertained the reusability of the adsorbent using toluene as the solvent for three adsorption-desorption cycles.

Mechanochemical Functionalization of Mesoporous Carbons for the Catalytic Transformation of trans-Ferulic Acid into Vanillin

Mesoporous carbonaceous materials were functionalized with iron or copper by a mechanochemical approach. The structural and textural properties of these catalysts were characterized by N2 physisorp...

Phase Behavior and Capillary Condensation Hysteresis of Carbon Dioxide in Mesopores.

Carbon dioxide adsorption on micro- and mesoporous carbonaceous materials in a wide range of temperatures and pressures is of great importance for the problems of gas separations, greenhouse gas capture and sequestration, enhanced hydrocarbon recovery from shales and coals, as well as for the characterization of nanoporous materials using CO2 as a molecular probe. We investigate the influence of temperature on CO2 adsorption focusing on the capillary condensation and hysteresis phenomena. We present experimental data on the adsorption of CO2 on CMK-3, ordered carbon with mesopores of ∼5-6 nm, at various temperatures (185-273 K) and pressures (up to 35 bars). Using Monte Carlo (MC) simulations in the grand canonical and mesocanonical ensembles, we attempt to predict the transition from reversible capillary condensation to hysteretic adsorption-desorption cycles that is experimentally observed with the decrease of temperature. We show that although the desorption at all temperatures occurs at the conditions of pore vapor-liquid equilibrium, the capillary condensation is a nucleation-driven process associated with an effective energy barrier of ∼43 kT, specific to the sample used in this work. This barrier can be overcome at the equilibrium conditions in the region of reversible condensation at temperatures higher than 240 K. At lower temperatures, the regime of developing hysteresis is observed with progressively widening hysteresis loops. The position of capillary condensation transition is estimated using the pressure dependence of the energy barrier calculated by the thermodynamic integration of the van der Waals-type continuous canonical isotherm simulated with the gauge cell MC method. These findings lay the foundation for developing kernels of CO2 adsorption and desorption isotherm for calculating the pore size distribution in the entire range of micropore and mesopore sizes from one high-pressure experimental isotherm.

Recovery of Adsorption Properties of Shungite

The condition of the surface of natural mesoporous carbonaceous material shungite has been investigated using the electron microscopy, X-ray phase and microspectrum analyses. The ability to recover the adsorption properties of shungite in respect to the extraction of higher alcohols and other impurities from water-alcohol solutions was investigated by the methods of thermogravimetry and IR spectroscopy. The main distinction of absorption spectra of used-up shungite with respect to the initial sample is the absence of absorption by hydroxyl groups (3380 cm−1) and significant reduction of the contribution of component at 1170 cm−1 that corresponds to absorption of phenol groups. It is shown that the heat treatment in argon, with water vapor and in the CO2 medium results in almost complete removal of sorbed organic substances and the regeneration of adsorption properties of shungite, the latest technique is more economically justified.

Adsorption of organic matter in oil sands process water (OSPW) by carbon xerogel

This study illustrated the preparation, characterization and the use of carbon xerogel materials for the adsorption of acid-extractable fractions (AEF) and naphthenic acids (NAs) from oil sands process water (OSPW). Adsorption results demonstrated that the mesoporous carbonaceous material can successfully be used to adsorb persistent and toxic organic contaminants from OSPW. Carbon xerogel (CX) made at pH 5.5 showed high surface area (573 m2/g) and removed a larger amount of AEF than CX made at pH 6.9 (391 m2/g). The adsorption equilibrium was reached by 24 h for both AEF and classical NAs. 74.6% of AEF and 88.8% of classical NAs were removed by CX5.5 during 24-h adsorption. With respect to classical NAs, a larger the carbon number resulted in higher NA removal. Carbon number had more influence on NA removal when compared with hydrogen deficiency resulting from rings or unsaturated bonding formation (–Z number). The equilibrium adsorption capacity was found to be 15 mg AEF/g and 7.8 mg NAs/g for CX5.5. Adsorption of AEF and classical NAs onto CX5.5 followed pseudo-second order kinetics. With respect to diffusion of AEF and NAs, there were three distinct diffusion regions: bulk, film and pore. Pore diffusion had the lowest rate constant in all cases analyzed and was thus the rate limiting step. The results of this study showed that a mesoporous carbonaceous material such as CX may have the potential to be utilized in a fixed bed adsorption/filtration systems for continuous treatment of OSPW or as a semi-passive treatment method in pit lakes for the removal of organic constituents from OSPW.

Alginic acid-derived mesoporous carbonaceous materials (Starbon®) as negative electrodes for lithium ion batteries: Importance of porosity and electronic conductivity

Alginic acid-derived mesoporous carbonaceous materials (Starbon® A800 series) were investigated as negative electrodes for lithium ion batteries. To this extent, a set of mesoporous carbons with different pore volume and electronic conductivity was tested. The best electrochemical performance was obtained for A800 with High Pore Volume (A800HPV), which displays both the highest pore volume (0.9 cm3 g−1) and the highest electronic conductivity (84 S m−1) of the tested materials. When compared to a commercial mesoporous carbon, A800HPV was found to exhibit both better long-term stability, and a markedly improved rate capability. The presence of a hierarchical interconnected pore network in A800HPV, accounting for a high electrolyte accessibility, could lay at the origin of the good electrochemical performance. Overall, the electronic conductivity and the mesopore size appear to be the most important parameters, much more than the specific surface area. Finally, A800HPV electrodes display similar electrochemical performance when formulated with or without added conductive additive, which could make for a simpler and more eco-friendly electrode processing.

Synthesis of ordered mesoporous carbonaceous materials and their highly efficient capture of uranium from solutions

An extremely effortless method was applied for successful synthesis of mesoporous carbonaceous materials (MCMs) using well-ordered mesoporous silica as template. Various characterizations (scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), Brunner-Emmet-Teller (BET) and Zeta potential) confirmed that MCMs had large surface area, uniform pore size distribution, and abundant oxygen-containing functional groups. The batch techniques were employed to study U(VI) adsorption on MCMs under a wide range of experiment conditions. The adsorption kinetics of U(VI) onto MCMs were well-fitted by pseudo-second-order kinetic model, indicating a chemisorption process. The excellent adsorption capacity of MCMs calculated from the Langmuir model was 293.95 mg g−1 at pH 4.0. The FT-IR and XPS analyses further evidenced that the binding of U(VI) onto MCMs was ascribed to the plentiful adsorption sites (–OH and –COOH groups) in the internal mesoporous structure, which could efficiently trap guest U(VI) ions. The results presented herein revealed that MCMs were ideal adsorbents in the efficient elimination of uranium or other lanthanides/actinides from aqueous solutions, which would play an important role in environmental pollution management application.

Ordered mesoporous carbon as sorbent for the extraction of N-nitrosamines in wastewater and swimming pool water

The analysis and determination of N-nitrosamines (NAs) in water samples are challenging and demanding. In this study, a simple, reliable, and practical methodology is reported for the quantitative determination by gas chromatography-tandem mass spectrometry with electron impact ionization (EI) and triple quadrupole analyzer (GC-EI-MS/MS) of eight NAs after micro-solid-phase extraction (μ-SPE) from wastewater and swimming pool water. Thirty milligram of an ordered mesoporous carbonaceous material, oxidative surface-modified CMK-3, enclosed within a porous polypropylene membrane bag, were used as sorbent for μ-SPE. A central composite design approach was applied to optimize the μ-SPE parameters. An isotopically-labeled NA was used as internal standard. Under the optimized conditions, μ-SPE-GC-EI-MS/MS was validated for an NA concentration range of between 0.1–100ng/mL. The precision of the method was evaluated and an average relative standard deviation of 4.8% (n=8) for a standard solution spiked at 50ng/mL of each NA was obtained. The limits of detection were measured to be in the range of 0.005–0.283ng/mL. Domestic wastewater and swimming pool water samples were used to evaluate the applicability of the method. NAs were detected in swimming pool water and wastewater at concentrations of <2ng/mL and 11ng/mL, respectively.

Optimization of the synthesis of Pd-Au nanoalloys confined in mesoporous carbonaceous materials

Pd-Au nanoalloys confined in mesoporous carbonaceous materials were synthesized by a rapid one-pot microwave assisted approach. Green polymer resins based on phloroglucinol/glyoxylic acid or glyoxal were co-assembled in the presence of a template and metallic salts followed by microwave treatment between 40 and 80°C and subsequent thermal annealing, allowing simultaneous formation of mesoporous carbonaceous materials with in-situ confined Pd-Au nanoparticles. Several Pd-Au compositions were prepared (PdxAu100−x, where x=90; 80; 70 and 50) and their impact on the alloy structure and particle size/distribution evaluated. For Pd90Au10, homogeneously dispersed nanoalloy particles (∼8nm) are obtained in the carbonaceous framework. The increase in the Au content in the alloy gradually induces an increase in the particle size and agglomeration of the particles along with the formation of multiphased alloys, i.e., segregated Pd- and Au-rich nanoparticles. The particle agglomeration was avoided by decreasing the thermal annealing time. The homogeneity of the alloy structure was found to strongly depend by two parameters, the chelating/cross-linker agents and the microwave temperature, i.e., the chelating/cross-linker agents containing carboxylic groups and the higher temperatures inducing more heterogeneous structures. The hydrogen absorption in Pd90Au10 particles with different homogeneity degree was studied at room temperature up to 1bar. Generally, hydrogen absorbs in Pd-rich nanoalloys forming a hydride phase whereas Au-rich phases do not absorb hydrogen under the present conditions.

Mesoporous carbonaceous material from fish scales as low-cost adsorbent for reactive orange 16 adsorption

Abstract This work investigates the possibility of utilizing carbonized fish ( Labeo rohita ) scales (CFS) as low-cost materials for the adsorption of reactive orange 16 dye (RO16) through batch processing. The textural and morphological characteristics of CFS were evaluated which showed mesoporous structure with BET surface area of 213.82 m 2 /g and average pore diameter of 5.116 nm. The effects of initial RO16 concentration (25–400 mg/l), solution pH (3–13), and temperature (30–50 °C) on the adsorption efficiency of the prepared CFS were demonstrated. The equilibrium isotherm data were best correlated using the Freundlich equation. The prepared CFS exhibited maximum adsorption capacities of 105.8, 107.2, and 114.2 mg/g at 30 °C, 40 °C, and 50 °C, respectively. The pseudo-second-order model well represented the adsorption kinetics. The prepared CFS had a high adsorption capacity for RO16 and could be utilized effectively for the removal of reactive dyes from wastewater.

Ordered Mesoporous Carbonaceous Materials with Tunable Surface Property for Enrichment of Hexachlorobenzene.

A gradient pyrolysis approach has been adopted for synthesis of ordered mesoporous carbonaceous materials with different surface and textural properties for removal of hexachlorobenzene. The resultant ordered mesoporous carbonaceous materials possess high surface areas (364-888 m2/g), large pore volumes (0.23-0.47 cm3/g), uniform pore sizes (2.6-3.8 nm), and tunable hydrophobic properties. They show high-efficiency removal performances for hexachlorobenzene with high adsorption capacity of 594.2-992.1 μg/g. An enhanced removal rate (>99%) can be obtained with the increasing pyrolysis temperature (900 °C) as a result of the strong hydrophobic-hydrophobic interaction between the carbon framework and hexachlorobenzene molecules. Furthermore, the adsorption behaviors follow the Sips isotherm model and obey the pseudo-first-order kinetic model.

Acid Induced Self-Assembly Strategy to Synthesize Ordered Mesoporous Carbons from Biomass

Hydrothermal carbonization of biomass is an economic and sustainable technique for the fabrication of functional carbonaceous materials. However, the introduction of biomass into synthesis of ordered mesoporous carbon materials achieves slow progress due to complicated requirements. It is still challenging to prepare biomass-derived ordered mesoporous carbon materials. Herein, we report a simple and effective strategy to synthesize ordered mesoporous carbon materials from renewable and environment-friendly pentose using one-pot hydrothermal synthesis. The as-synthesized ordered mesoporous carbon materials show mesopores of two-dimensional hexagonal symmetry and rich functional groups. Mechanism studies indicate that the acid facilitates the self-assembly of carbon precursors and soft templates and therefore induced the formation of ordered mesoporous carbonaceous materials under hydrothermal conditions. This is the first report on the S0H+X–I+ self-assembly mechanism that achieves success in biomass syste...

Importance of Micropore-Mesopore Interfaces in Carbon Dioxide Capture by Carbon-Based Materials.

Mesoporous carbonaceous materials (Starbons®) derived from low-value/waste bio-resources separate CO2 from CO2 /N2 mixtures. Compared to Norit activated charcoal (AC), Starbons® have much lower microporosities (8-32 % versus 73 %) yet adsorb up to 65 % more CO2 . The presence of interconnected micropores and mesopores is responsible for the enhanced CO2 adsorption. The Starbons® also showed three-four times higher selectivity for CO2 adsorption rather than N2 adsorption compared to AC.