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Adsorption Materials and Adsorption Behavior

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Physical Chemistry and Chemical Physics".

Deadline for manuscript submissions: closed (15 January 2023) | Viewed by 21024

Special Issue Editor

College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China
Interests: electrochemical capacitors; cobaltous sulfide; electrode materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Adsorption is the adhesion of various gases, vapors, and solutes in solutions on the surface of solid or liquid substances. Based on the nature of the binding force between adsorbate and adsorbent, adsorption can be divided into physical adsorption and chemical adsorption. The driving force of physical adsorption is intermolecular force, while that of chemical adsorption is the chemical bonds between adsorbate and adsorbent. Physical adsorption and chemical adsorption are not isolated but often occur together.

Adsorption has been widely used in the removal of heavy metal ions from water, the recovery and extraction of various resources, the removal of toxic and harmful gases, and so on. The key to the application of adsorption technology is the selection and design of adsorption materials. Common adsorption materials include carbon materials, metal–organic frameworks, polymer materials, gels, metals, and nonmetallic compounds. The adsorption behavior of materials can be affected by many factors from the adsorbate and the chemical properties of adsorbents. The study of adsorption mechanisms is also very important to improve adsorption efficiency.

The purpose of this Special Issue is to focus on studies about the microstructure design of adsorption materials, molecular behavior on materials’ surface, and related adsorption mechanisms. We are pleased to invite you to contribute related original articles or reviews.

Prof. Dr. Jun Wang
Guest Editor

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Keywords

  • adsorption
  • adsorption materials
  • adsorption behavior
  • adsorption mechanism
  • adsorption thermodynamics and kinetics
  • resource extraction
  • pollutant removal
  • separation

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Published Papers (12 papers)

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Research

24 pages, 7768 KiB  
Article
The Effect of Sorbent Composition on Sorption Properties of Materials Based on Ti-Ca-Mg Phosphates
Int. J. Mol. Sci. 2023, 24(9), 7903; https://doi.org/10.3390/ijms24097903 - 26 Apr 2023
Viewed by 841
Abstract
Individual titanium and calcium–magnesium phosphates are widely known as effective sorbents. The sorption processes on these phosphates are based on different mechanisms. The sorption efficiency towards different cations depends on the phase composition of the sorbent. Composite materials with various ratio Ti:(Ca+Mg) have [...] Read more.
Individual titanium and calcium–magnesium phosphates are widely known as effective sorbents. The sorption processes on these phosphates are based on different mechanisms. The sorption efficiency towards different cations depends on the phase composition of the sorbent. Composite materials with various ratio Ti:(Ca+Mg) have been synthesized. The sorption properties of samples obtained towards Cs+, Sr2+, Co2+, Cd2+, Zn2+, Cu2+, and Pb2+ have been studied to establish the effect of sorbent composition on metal removal. The adsorption isotherms have been analyzed using the Langmuir, Freundlich, and Redlich–Peterson models. The composition of sorbents has no effect on the level of removal of readily hydrolyzable Pb2+ and Cu2+ cations. Removal of lead occurs preferentially via the precipitation of metal phosphates and hydroxides. Copper precipitates as hydroxide in case of a high share of Ca-Mg phosphates in the composite sorbent. The removal of cesium proceeds according to the ion exchange mechanism only. For Cd2+, Co2+, Sr2+, and Zn2+ cations, the sorption efficiency on the composite materials synthesized is found to increase with the increase in titanium phosphate’s share in the sample. All composite sorbents synthesized demonstrated a considerable increase in the level of purification of solutions studied compared with individual Ti and Ca-Mg phosphates due to the synergism of the components. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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22 pages, 8061 KiB  
Article
Effect of CeO2-Reinforcement on Pb Absorption by Coconut Coir-Derived Magnetic Biochar
Int. J. Mol. Sci. 2023, 24(3), 1974; https://doi.org/10.3390/ijms24031974 - 19 Jan 2023
Cited by 1 | Viewed by 1608
Abstract
Magnetic separable biochar holds great promise for the treatment of Pb2+-contaminated wastewater. However, the absorption effect of unmodified magnetic biochar is poor. Considering this gap in knowledge, CeO2-doped magnetic coconut coir biochar (Ce-MCB) and magnetic coconut coir biochar (MCB) [...] Read more.
Magnetic separable biochar holds great promise for the treatment of Pb2+-contaminated wastewater. However, the absorption effect of unmodified magnetic biochar is poor. Considering this gap in knowledge, CeO2-doped magnetic coconut coir biochar (Ce-MCB) and magnetic coconut coir biochar (MCB) for Pb2+ absorption were prepared by the impregnation method, and the efficiency of Ce-MCB for Pb2+ absorption was evaluated in comparison with MCB. Conducting the absorption experiments, the study provided theoretical support for the exploration of the absorption mechanism. The quantitative analysis exposed that the enhanced absorption capacity of Ce-MCB was attributed to the increase in oxygen-containing functional groups and mineral precipitation. The Langmuir and Freundlich isotherm model showed that Ce-MCB is a suitable adsorbent for Pb2+. The absorption characteristics of Ce-MCB was fit well with the pseudo-second-order (PSO) and Langmuir models, which revealed that the absorption of Pb2+ in water was monolayer chemisorption with a maximum theoretical adsorption capacity of 140.83 mg·g−1. The adsorption capacity of Ce-MCB for Pb(II) was sustained above 70% after four cycles. In addition, the saturation magnetization intensity of Ce-MCB was 7.15 emu·g−1, which was sufficient to separate out from the solution. Overall, Ce-MCB has wide application prospects in terms of biomass resources recycling and environmental conservation. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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14 pages, 2970 KiB  
Article
Highly Efficient Removal of Uranium from an Aqueous Solution by a Novel Phosphonic Acid-Functionalized Magnetic Microsphere Adsorbent
Int. J. Mol. Sci. 2022, 23(24), 16227; https://doi.org/10.3390/ijms232416227 - 19 Dec 2022
Cited by 3 | Viewed by 1717
Abstract
The development of adsorption materials which can efficiently isolate and enrich uranium is of great scientific significance to sustainable development and environmental protection. In this work, a novel phosphonic acid-functionalized magnetic microsphere adsorbent Fe3O4/P (GMA-MBA)-PO4 was developed by [...] Read more.
The development of adsorption materials which can efficiently isolate and enrich uranium is of great scientific significance to sustainable development and environmental protection. In this work, a novel phosphonic acid-functionalized magnetic microsphere adsorbent Fe3O4/P (GMA-MBA)-PO4 was developed by functionalized Fe3O4/P (GMA-MBA) prepared by distill-precipitation polymerization with O-phosphoethanolamine. The adsorption process was endothermic, spontaneous and kinetically followed the pseudo second-order model. The maximum uranium adsorption capacity obtained from the Langmuir model was 333.33 mg g−1 at 298 K. In addition, the adsorbent also had good acid resistance and superparamagnetic properties, which could be quickly separated by a magnetic field. XPS analysis showed that the adsorption of adsorbent mainly depended on the complexation of phosphonic acid group with uranium. This work offers a promising candidate for the application of magnetic adsorbents in the field of uranium separation and enrichment. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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19 pages, 4597 KiB  
Article
Adsorption of Chromium (VI) Using an Activated Carbon Derived from Petroleum Coke Feedstock
Int. J. Mol. Sci. 2022, 23(24), 16172; https://doi.org/10.3390/ijms232416172 - 18 Dec 2022
Cited by 5 | Viewed by 2153
Abstract
This study aims to determine the main adsorption mechanism by which chromium (VI) is adsorbed onto the surface of a petroleum-coke sourced activated carbon, a feedstock not prevalent in current literature. The study also aims to produce an activated carbon adsorbent that is [...] Read more.
This study aims to determine the main adsorption mechanism by which chromium (VI) is adsorbed onto the surface of a petroleum-coke sourced activated carbon, a feedstock not prevalent in current literature. The study also aims to produce an activated carbon adsorbent that is both cost-effective and efficient for the removal of chromium (VI) in neutral waters. The efficacy of thermally-treated petroleum coke-activated carbon and nitrogenated petroleum coke-activated carbon using ammonium chloride is compared to the efficacy of commercially available activated carbon. X-ray photoelectron spectroscopy of the activated carbons was obtained both before and after exposure to chromium (VI) for characterization of the materials and confirmation of chromium adsorption. The thermally-treated and nitrogenated activated carbons showed significant enhancement of chromium (VI) removal compared to the non-treated petroleum coke-activated carbon (22.4 mg/g, 21.9 mg/g, and 17.0 mg/g, respectively). However, there was no significant difference observed between the thermally-treated and nitrogenated materials. This indicates that the nitrogenation of the surface does not improve the adsorption capacity of the activated carbon, but rather the thermal treatment itself. X-ray photoelectron spectroscopy showed a significant increase in the alcohol functional groups on the surface of the activated carbon material as a result of the heat-treatment process; from 16.02 atomic percent in the non-treated activated carbon to 26.3 atomic percent in the thermally-treated activated carbon. The alcohol functional groups present on the surface allow for chromium (VI) to undergo reduction to chromium (III) under a similar mechanism to the well-known Jones Oxidation Reaction where the reduced chromium (III) species are then physisorbed to the surface of the activated carbon. XPS results are consistent with this as the chromium species present on the surface of the adsorbent is primarily Cr(OH)3 (85.6% in the standard AC and 82.5% in the thermally-treated AC). Pseudo-first-order and pseudo-second-order kinetic modeling of the adsorbents indicate that they follow a pseudo-second-order reaction where the rate-limiting step is the chemical sorption of the adsorbate itself. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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14 pages, 5259 KiB  
Article
Layered Double Hydroxides Derived from MIL-88A(Fe) as an Efficient Adsorbent for Enhanced Removal of Lead (II) from Water
Int. J. Mol. Sci. 2022, 23(23), 14556; https://doi.org/10.3390/ijms232314556 - 22 Nov 2022
Cited by 3 | Viewed by 1346
Abstract
The efficient removal of lead (II) from aqueous solution remains a big problem and the development of novel nanomaterials as adsorbents by various technologies to solve this problem is promising. This study contributed a novel nanostructure of MIL-88A-layered double hydroxides (LDHs) as the [...] Read more.
The efficient removal of lead (II) from aqueous solution remains a big problem and the development of novel nanomaterials as adsorbents by various technologies to solve this problem is promising. This study contributed a novel nanostructure of MIL-88A-layered double hydroxides (LDHs) as the adsorbent for Pb2+, which was synthesized by a two-step solvothermal method with MIL-88A(Fe) as the precursor. The as-prepared material featured a chestnut-like core-shell structure, and exhibited excellent removal performance towards Pb2+ from water in comparison to MIL-88A(Fe) and LDHs (directly synthesized). The adsorption of Pb2+ by the MIL-88A-LDHs conformed to the pseudo-second-order kinetic model and the Langmuir and Freundlich isotherm models. The maximal adsorption capacity was 526.32, 625.00, and 909.09 mg g−1 at 278, 298, and 318 K, respectively. The thermodynamic parameters suggested that the adsorption was an endothermic, entropy-increasing, and spontaneous reaction. X-ray photoelectron spectroscopy (XPS) analysis indicated that the surface complexation was mostly responsible for Pb2+ elimination. The MIL-88A-LDHs can be readily regenerated and showed good cyclic performance towards Pb2+. Thus, the as-prepared MIL-88A-LDHs may hold promise for the elimination of aqueous heavy metals. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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16 pages, 3928 KiB  
Article
Investigation on Purification of Saturated LiNO3 Solution Using Titanium Phosphate Ion Exchanger: Kinetics Study
Int. J. Mol. Sci. 2022, 23(21), 13416; https://doi.org/10.3390/ijms232113416 - 02 Nov 2022
Cited by 2 | Viewed by 1229
Abstract
Lithium compounds are of high interest to many industries. The presence of undesirable impurities in Li precursors leads to uncontrolled change in the functional properties of final compounds. Therefore, the development of reliable methods for lithium salt purification is considered a key factor [...] Read more.
Lithium compounds are of high interest to many industries. The presence of undesirable impurities in Li precursors leads to uncontrolled change in the functional properties of final compounds. Therefore, the development of reliable methods for lithium salt purification is considered a key factor for their application in various industries. This work focuses on the application of a titanium phosphate ion exchanger (Li-TiOP) toward Cu2+, Co2+, Mn2+, Ni2+, and Cr3+ ions in the purification of a saturated LiNO3 solution. The sorption kinetics of the selected ions, considering external and internal mass transfer, as well as chemical interaction, were deeply studied. The kinetic study showed that the values of intraparticle diffusion rate and effective diffusion coefficients for the studied ions decreased in the following order: Cr(III) ˃ Cu(II) Mn(II) ˃ Co(II) ˃ Ni(II). For all the selected ions, chemical interaction was described with a pseudo-second-order reaction model. The sorption kinetics were controlled by the size of the solvated metal ion, its effective charge, the electronic structure of the adsorbed ion, and the interaction with the functional groups of the sorbent. Due to fast kinetics, the high degree of removal of trace quantities of the impurities this material gives it consideration as a promising sorbent for the deep purification of lithium salts. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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16 pages, 7047 KiB  
Article
Magnetic Separation of Oxoacid of Boron from Salt-Lake Brine by Synergistically Enhanced Boron Adsorbents of Glucose-Functionalized SiO2 and Graphene
Int. J. Mol. Sci. 2022, 23(19), 11356; https://doi.org/10.3390/ijms231911356 - 26 Sep 2022
Cited by 4 | Viewed by 1085
Abstract
The adsorption separation and extraction of low-concentration boron from salt-lake brine have great significance. Magnetic separation avoids the problem of adsorbent granulation and improves the usage efficiency. The silicon-based adsorbents have attracted interest due to their superior acid and alkali resistance, in which [...] Read more.
The adsorption separation and extraction of low-concentration boron from salt-lake brine have great significance. Magnetic separation avoids the problem of adsorbent granulation and improves the usage efficiency. The silicon-based adsorbents have attracted interest due to their superior acid and alkali resistance, in which polyhydroxy graphene enhances the adsorption of boron ions. Herein different boron adsorbents, derived by magnetic separation, were developed and characterized by SEM, TEM, XPS, VSM, FT-IR, and XRD analysis. The adsorption-desorption performance of boron adsorbents with different compositions was evaluated. The isotherms and kinetics parameters of the boron extraction were evaluated based on adsorption-desorption tests. The graphene-based magnetic adsorbent (Go-Fe3O4@SiO2@mSiO2-Glu) registered a high boron adsorption capacity of 23.90 mg/g at pH = 9 in the boron solution and 24.84 mg/g for East Taigener salt-lake brine. The Na+, Mg2+, Ca2+, and Cl ions have little interference with the boron adsorption. The adsorbents exhibit magnetic separation performance and good cycle life. The results showed that acid-alkali desorption solution has little effect on the adsorbents, and the composite of graphene enhances the adsorption of boron ions. The adsorbents developed in this study are promising to recover boron from low-concentration boron-containing salt-lake brines. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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18 pages, 2678 KiB  
Article
Rhamnolipid Micellization and Adsorption Properties
Int. J. Mol. Sci. 2022, 23(19), 11090; https://doi.org/10.3390/ijms231911090 - 21 Sep 2022
Cited by 11 | Viewed by 2344
Abstract
Biosurfactants are naturally occurring amphiphiles that are being actively pursued as alternatives to synthetic surfactants in cleaning, personal care, and cosmetic products. On the basis of their ability to mobilize and disperse hydrocarbons, biosurfactants are also involved in the bioremediation of oil spills. [...] Read more.
Biosurfactants are naturally occurring amphiphiles that are being actively pursued as alternatives to synthetic surfactants in cleaning, personal care, and cosmetic products. On the basis of their ability to mobilize and disperse hydrocarbons, biosurfactants are also involved in the bioremediation of oil spills. Rhamnolipids are low molecular weight glycolipid biosurfactants that consist of a mono- or di-rhamnose head group and a hydrocarbon fatty acid chain. We examine here the micellization of purified mono-rhamnolipids and di-rhamnolipids in aqueous solutions and their adsorption on model solid surfaces. Rhamnolipid micellization in water is endothermic; the CMC (critical micellization concentration) of di-rhamnolipid is lower than that of mono-rhamnolipid, and both CMCs decrease upon NaCl addition. Rhamnolipid adsorption on gold surface is mostly reversible and the adsorbed layer is rigid. A better understanding of biosurfactant self-assembly and adsorption properties is important for their utilization in consumer products and environmental applications. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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22 pages, 6298 KiB  
Article
IL-Functionalized Mg3Al-LDH as New Efficient Adsorbent for Pd Recovery from Aqueous Solutions
Int. J. Mol. Sci. 2022, 23(16), 9107; https://doi.org/10.3390/ijms23169107 - 14 Aug 2022
Cited by 3 | Viewed by 1213
Abstract
Palladium is a noble metal of the platinum group metals (PGMs) with a high value and major industrial applications. Due to the scarce palladium resources, researchers’ attention is currently focused on Pd ions recovery from secondary sources. Regarding the recovery process from aqueous [...] Read more.
Palladium is a noble metal of the platinum group metals (PGMs) with a high value and major industrial applications. Due to the scarce palladium resources, researchers’ attention is currently focused on Pd ions recovery from secondary sources. Regarding the recovery process from aqueous solutions, many methods were studied, amongst which adsorption process gained a special attention due to its clear advantages. Moreover, the efficiency and the selectivity of an adsorbent material can be further improved by functionalization of various solid supports. In this context, the present work aims at the synthesis and characterization of Mg3Al-LDH and its functionalization with ionic liquid (IL) (Methyltrialkylammonium chloride) to obtain adsorbent materials with high efficiency in Pd removal from aqueous solutions. The maximum adsorption capacity developed by Mg3Al-LDH is 142.9 mg Pd., and depending on the functionalization method used (sonication and co-synthesis, respectively) the maximum adsorption capacity increases considerably, qmax-Mg3Al IL-US = 227.3 mg/g and qmax-Mg3Al IL-COS = 277.8 mg/g. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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12 pages, 3056 KiB  
Article
Theory-Guided Design of a Method to Obtain Competitive Balance between U(VI) Adsorption and Swaying Zwitterion-Induced Fouling Resistance on Natural Hemp Fibers
Int. J. Mol. Sci. 2022, 23(12), 6517; https://doi.org/10.3390/ijms23126517 - 10 Jun 2022
Cited by 3 | Viewed by 1206
Abstract
The competitive balance between uranium (VI) (U(VI)) adsorption and fouling resistance is of great significance in guaranteeing the full potential of U(VI) adsorbents in seawater, and it is faced with insufficient research. To fill the gap in this field, a molecular dynamics (MD) [...] Read more.
The competitive balance between uranium (VI) (U(VI)) adsorption and fouling resistance is of great significance in guaranteeing the full potential of U(VI) adsorbents in seawater, and it is faced with insufficient research. To fill the gap in this field, a molecular dynamics (MD) simulation was employed to explore the influence and to guide the design of mass-produced natural hemp fibers (HFs). Sulfobetaine (SB)- and carboxybetaine (CB)-type zwitterions containing soft side chains were constructed beside amidoxime (AO) groups on HFs (HFAS and HFAC) to form a hydration layer based on the terminal hydrophilic groups. The soft side chains were swayed by waves to form a hydration-layer area with fouling resistance and to simultaneously expel water molecules surrounding the AO groups. HFAS exhibited greater antifouling properties than that of HFAO and HFAC. The U(VI) adsorption capacity of HFAS was almost 10 times higher than that of HFAO, and the max mass rate of U:V was 4.3 after 35 days of immersion in marine water. This paper offers a theory-guided design of a method to the competitive balance between zwitterion-induced fouling resistance and seawater U(VI) adsorption on natural materials. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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19 pages, 6821 KiB  
Article
Waste-to-Resource Strategy to Fabricate Functionalized MOFs Composite Material Based on Durian Shell Biomass Carbon Fiber and Fe3O4 for Highly Efficient and Recyclable Dye Adsorption
Int. J. Mol. Sci. 2022, 23(11), 5900; https://doi.org/10.3390/ijms23115900 - 24 May 2022
Cited by 16 | Viewed by 2588
Abstract
Recently, metal–organic frameworks (MOFs), which are porous inorganic–organic hybrid materials consisting of metal ions (clusters or secondary building units) and organic ligands through coordination bonds, have attracted wide attention because of their high surface area, huge ordered porosity, uniform structural cavities, and excellent [...] Read more.
Recently, metal–organic frameworks (MOFs), which are porous inorganic–organic hybrid materials consisting of metal ions (clusters or secondary building units) and organic ligands through coordination bonds, have attracted wide attention because of their high surface area, huge ordered porosity, uniform structural cavities, and excellent thermal/chemical stability. In this work, durian shell biomass carbon fiber and Fe3O4 functionalized metal–organic framework composite material (durian shell fiber-Fe3O4-MOF, DFM) was synthesized and employed for the adsorption removal of methylene blue (MB) from wastewater. The morphology, structure, and chemical elements of the DFM material were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscope (XPS) techniques. Adsorption conditions such as pH, adsorption time, and temperature were optimized. The adsorption isotherm and kinetics results show that the adsorption process of DFM material to MB is more in line with the Freundlich model and pseudo-second-order kinetic model. Using these models, the maximum adsorption capacity of 53.31 mg/g was obtained by calculation. In addition, DFM material could be easily reused through an external magnet and the removal rate of MB was still 80% after five adsorption cycles. The obtained results show that DFM composite material, as an economical, environmentally friendly, recyclable new adsorbent, can simply and effectively remove MB from wastewater. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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11 pages, 3814 KiB  
Communication
Template-Free Preparation of a Mesopore-Rich Hierarchically Porous Carbon Monolith from a Thermally Rearrangeable Polyurea Network
Int. J. Mol. Sci. 2022, 23(8), 4271; https://doi.org/10.3390/ijms23084271 - 12 Apr 2022
Viewed by 1540
Abstract
A mesopore-rich, hierarchically porous carbon monolith was prepared by carbonizing a polyisocyanurate network derived by thermal rearrangement of a polyurea network. The initial polyurea network was synthesized by the cross-linking polymerization of tetrakis(4-aminophenyl)methane (TAPM) and hexamethylene diisocyanate (HDI) in the sol-forming condition, followed [...] Read more.
A mesopore-rich, hierarchically porous carbon monolith was prepared by carbonizing a polyisocyanurate network derived by thermal rearrangement of a polyurea network. The initial polyurea network was synthesized by the cross-linking polymerization of tetrakis(4-aminophenyl)methane (TAPM) and hexamethylene diisocyanate (HDI) in the sol-forming condition, followed by precipitation into nanoparticulate solids in a nonsolvent. The powder was molded into a shape and then heated at 200–400 °C to obtain the porous carbon precursor composed of the rearranged network. The thermolysis of urea bonds to amine and isocyanate groups, the subsequent cyclization of isocyanates to isocyanurates, and the vaporization of volatiles caused sintering of the nanoparticles into a monolithic network with micro-, meso-, and macropores. The rearranged network was carbonized to obtain a carbon monolith. It was found that the rearranged network, with a high isocyanurate ratio, led to a porous carbon with a high mesopore ratio. The electrical conductivity of the resulting carbon monoliths exhibited a rapid response to carbon dioxide adsorption, indicating efficient gas transport through the hierarchical pore structure. Full article
(This article belongs to the Special Issue Adsorption Materials and Adsorption Behavior)
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