Silica Adsorbents Research Articles

Vacuum-Assisted MonoTrapTM Extraction for Volatile Organic Compounds (VOCs) Profiling from Hot Mix Asphalt.

MonoTrapTM was introduced in 2009 as a novel miniaturized configuration for sorptive sampling. The method for the characterization of volatile organic compound (VOC) emission profiles from hot mix asphalt (HMA) consisted of a two-step procedure: the analytes, initially adsorbed into the coating in no vacuum- or vacuum-assistance mode, were then analyzed following an automated thermal desorption (TD) step. We took advantage of the theoretical formulation to reach some conclusions on the relationship between the physical characteristics of the monolithic material and uptake rates. A total of 35 odor-active volatile compounds, determined by gas chromatography-mass spectrometry/olfactometry analysis, contributed as key odor compounds for HMA, consisting mainly of aldehydes, alcohols, and ketones. Chemometric analysis revealed that MonoTrapTM RGC18-TD was the better coating in terms of peak area and equilibrium time. A comparison of performance showed that Vac/no-Vac ratios increased, about an order of magnitude, as the boiling point of target analytes increased. The innovative hybrid adsorbent of silica and graphite carbon monolith technology, having a large surface area bonded with octadecylsilane, showed effective adsorption capability, especially to polar compounds.

Phytosterol Depletion in Soybean Oil Using a Synthetic Silica Adsorbent

Phytosterols in vegetable oils have gained attention for their nutritional benefits in foods and food supplements. However, the use of vegetable oils in emulsions for infant formulas and parenteral nutrition has raised some concerns, as phytosterols may contribute to phytosterolemia in the case of infant formulas and, in a second scenario, to parenteral nutrition-associated liver disease. The present study proposes removing phytosterols from soybean oil using a synthetic amorphous silica Trisyl® (E551) as an adsorbent material. The process is simple and involves stirring the oil at a high temperature under vacuum conditions followed by filtration to remove the adsorbent. A rotational factorial design of experiments, considering the adsorbent/oil ratio, temperature, and time was carried out to determine the optimal conditions. Additionally, the effects on tocopherols levels and formation of trans fatty acids were explored. The total sterol content in the initial refined soybean oil was 2540 mg/kg, with 32% in ester form (813 mg/kg). The treatments effectively reduced the sterol concentration, achieving a reduction of nearly 70% when 10% Trisyl®, 140 °C, and a 90-min treatment were applied. Under these conditions, nearly 80% of the oil was recovered. Campesterol and stigmasterol levels were almost halved. Tocopherol losses were found to be below 20%. Thermal degradation, as analyzed by triacylglycerol polymers and trans fatty acids, was not observed in the treatments.

Organic matter excreted by the protozoan Tetrahymena thermophila and its effects on the bioaccumulation of nanoparticles

Although organic matter (exudate) excreted by aquatic organisms is an important component of dissolved organic matter (DOM) in the natural environment, its potential effects on the bioaccumulation of nanoparticles (NPs) remain unclear. In the present study, we examined the effects of the exudates from the protozoan Tetrahymena thermophila on the bioaccumulation (including uptake and cell surface adsorption) of iron oxide (Fe2O3, polyacrylate coated) and silica (SiO2) NPs in T. thermophila. The exudates were mostly (93.6%, in carbon) composed of < 1-kDa molecules (e.g., lipids). When the exudates were mixed with the NPs, significant adsorption occurred on SiO2 NPs but not on Fe2O3 NPs. Independent of their adsorption by the NPs, the exudates significantly inhibited the bioaccumulation of both SiO2 NPs and Fe2O3 NPs by T. thermophila. This inhibitory effect was shown to be mainly due to their inhibition of NP adsorption on the cell surface. By contrast, the exudates had negligible effects on the uptake of either NP type, most likely due to their low molecular weight. Since DOM in the aquatic environment is dominated by molecules < 1kDa, the potential effects of low-molecular-weight DOM, such as exudates from aquatic organisms, on the bioaccumulation of NPs merits greater attention. Environmental ImplicationNanoparticles (NPs) are hazardous materials widespread in the natural environment. Previous studies showed that dissolved organic matter (DOM) in aquatic environments determine the environmental behavior and ecological effects of NPs. Although organic matter (exudate) excreted by aquatic organisms is an important component of DOM, its potential effects on the bioaccumulation of NPs remain unclear. In the present study, we found that the exudates inhibited the cell-surface adsorption of NPs but had no effects on NP uptake, as different from the well-known effects of DOM on NP bioaccumulation. This finding merits attention during evaluations of the environmental risks of NPs.

Polymer‐Sorbent Direct Air Capture Contactors with Complex Geometries 3D‐Printed via Templated Phase Inversion

AbstractLow‐cost direct air capture (DAC) systems require efficient gas–solid contactors. These contactors provide rapid rates of heat and mass transport with minimal pressure drops. Triply periodic minimal surfaces (TPMS) are a class of geometries that are shown to have heat transfer properties that exceed those of other geometries, and these benefits are expected to manifest in mass transfer as well due to the analogies between heat and mass transfer. However, creating TPMS contactors is difficult using conventional manufacturing techniques such as injection molding. Non‐solvent‐induced phase separation (NIPS) of a polymeric ink containing the adsorbent is one way to construct adsorption contactors with excellent mass transport rates, but contactors have to date only been fabricated in simple geometries (e.g., films, fibers). This study demonstrates that NIPS of polymeric inks occurs within a simultaneously‐dissolving, water‐soluble, 3D‐printed template. This templated phase inversion (TPI) technique can create seemingly unlimited macroscopic architectures, including TPMS contactors, using a variety of potential DAC adsorbents, including zeolite, silica, activated carbon, and metal–organic frameworks. SEM, micro‐computed tomography, and nitrogen adsorption experiments reveal the microscopic pore structures and macroscopic geometries of the resulting sorbent contactors. TPMS DAC contactors with poly(ethyleneimine)/silica adsorbents are shown to have CO2 capture performances that rival or exceed other contactor geometries.

Synthesis and Property Control of Bead-Shaped Silica Adsorbents for Rhodamine B Dye Adsorption

Synthesis and Property Control of Bead-Shaped Silica Adsorbents for Rhodamine B Dye Adsorption

Dimercaprol-modified mesoporous silica nanoparticles for efficient removal of toxic mercury ions from aqueous solution.

A surface-modified mesoporous silica nanoparticle containing dimercaprol monomers was created utilizing the sol-gel condensation process, using tetraethyl orthosilicate (TEOS) as the silica source and poloxamer as the structure directing agent. To accomplish this synthesis, 3-glycidoxypropyl triethoxysilane (GPTS, 20mol%) was incorporated into the silica walls during the sol-gel condensation process, along with TEOS. Furthermore, dimercaprol (DM) monomers were incorporated onto silica surfaces by a ring-opening reaction between GPTS epoxy groups, and dimercaprol hydroxyl groups. The prepared dimercaprol-modified silica adsorbent (MSN-DT NPs) material has been studied using a variety of instruments, including XRD, FT-IR, N2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric (TG) analysis, and zeta potential analysis. The MSN-DT NPs material selectively adsorbs mercury ions, with a high adsorption amount of 125mg/g and a removal capability of roughly ~ 90% from the original metal ion mixture comprising other competing metals such as Pb2+, Ni2+, Fe2+, and Zn2+. The MSN-DT NPs adsorbent shows recyclable qualities for up to five cycles when treated with an acidic aqueous solution (0.1M HCl). As a result, the MSN-DT NPs adsorbent may be regenerated and reused up to five times without losing its adsorption effectiveness. The experimental findings showed that the MSN-DT NPs adsorbent may be employed to selectively remove hazardous Hg2+ ions from an aqueous solution.

Enhancing the uranium (VI) adsorption performance of phosphoric acid functionalized porous silica by controlled introduction of phosphoric acid group

The post-grafting of porous silica with organic group is a common method for the synthesis of organo-functionalized silica adsorbent. However, this method usually produces adsorbents with limited adsorption performances due to the pore blocking caused by the irregular introduction of organic group. In this work, we report the controllable synthesis of phosphoric acid functionalized porous silica adsorbent based on the co-condensation method for uranium (VI) adsorptive removal with enhanced adsorption performance. Characterizations of the obtained silica verify its porous structure and confirm the homogeneous distribution of phosphoric acid groups inside the silica. This silica is able to efficiently remove 98 % of uranium from a 100 mg/L uranium (VI) solution within 10 min at a dosage of 0.6 g/L and the maximum uranium (VI) adsorption amount reaches 509 mg/g. Both adsorption capacity and adsorption rate of this silica are superior than that of the silica synthesized based on conventional post-grafting method. Moreover, this silica can be reused for five times with uranium (VI) removal efficiency above 95 % and it is well applied in adsorption column for dynamically adsorptive removal of uranium (VI) from real nuclear wastewater. Mechanism-related investigations reveal that uranium (VI) adsorption on this silica proceeds by effective ion exchange of uranium (VI) ion with either phosphoric acid or silanol group and the formation of uranyl phosphonate or uranyl silicate complex. This work provides a feasible strategy to synthesize functionalized porous silica without significant pore blocking, and demonstrates the enhancement effect of regulating surface adsorption groups on the adsorption performances of porous silica. Besides, this work offers a promising adsorbent for efficient treatment of uranium-containing nuclear wastewater and reveals the mechanism of uranium adsorption on those silica adsorbent containing phosphoric acid, thiol or thioether group.

Construction of quaternary ammonium nitroxy-hybrid magnetic mesoporous silica adsorbent system and its selective adsorption research of Re(Ⅶ)/Cu(Ⅱ)

This study focussed on the development of a quaternary ammonium nitroxy-hybrid magnetic mesoporous silica adsorption system (Fe3O4@MS-SiO2@3-CPTES@Tetra-N-ACE, Fe3O4@MS-SiO2@3-CPTES@Tetra-2N@ACE and Fe3O4@MS-SiO2@3-CPTES@Tetra-DE) was established with adsorption structures consisting of 1,4,7,10,13-pentaoxa-16-azacyclooctadecane (N-ACE), 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (2N-ACE) and a similar linear structure, 3,6-dioxy-1,8-octylenediamine (DE) for the selective separation of Re/Cu. The composites were characterized by Fourier transform Infrared spectroscopy(FT-IR), Energy dispersive spectrometer(EDS), X-ray Diffraction(XRD), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) measurements. The characterization of composites exhibits mesoporous and rich functional groups. The experimental results demonstrated that the Fe3O4@MS-SiO2@3-CPTES@Tetra-2N@ACE and Fe3O4@MS-SiO2@3-CPTES@Tetra-DE possessed superior adsorption capacities of Re(VII) in a wide acidic environment (pH=3–6). The maximum adsorption capacity of Fe3O4@MS-SiO2@3-CPTES@Tetra-2N@ACE and Fe3O4@MS-SiO2@3-CPTES@Tetra-DE were respectively up to 331.77 mg·g−1, 395.54 mg·g−1 at pH 5.0. Furthermore, the adsorption rate of these adsorbents was fast for only 2 h to absorb more than 80 % of Re(VII). Notably, when Fe3O4@MS-SiO2@3-CPTES@Tetra-2N@ACE and Fe3O4@MS-SiO2@3-CPTES@Tetra-DE were added into the rhenium copper binary solution with the concentration ratio from 1:1 and 1:50, the Re (Ⅶ) / Cu (Ⅱ) selectivity was constantly excellent (SelRe/Cu value > 1.46, SelRe/Cu max = 4.96). After 5 desorption processes for Re (Ⅶ) with 3 mol·L−1 NaCl and 1 mol·L−1 NaCl, respectively, the adsorption efficiency decreased by less than 10 % at Fe3O4@MS-SiO2@3-CPTES@Tetra-2N@ACE and Fe3O4@MS-SiO2@3-CPTES@Tetra-DE. The adsorption mechanism between the adsorbents and Re(VII) was mainly electrostatic interaction and ion exchange through TEM-EDS, FT-IR, and XPS. This novel adsorption system had a promising application in the selective separation of Re(VII)/Cu(Ⅱ).

Synthesis of bis(2-aminoethyl)amine functionalized mesoporous silica (SBA-15) adsorbent for selective adsorption of Pb2+ ions from wastewater.

Rapid growth in the industry has released large quantities of contaminants, particularly metal discharges into the environment. Heavy metal poisoning in water bodies has become a major problem due to its toxicity to living organisms. In this study, we developed a 3-chloropropyl triethoxysilane incorporated mesoporous silica nanoparticle (SBA-15) based adsorbent utilizing the sol-gel process and Pluronic 123 (P123) as a structure-directing surfactant. Furthermore, the produced SBA-15 NPs were functionalized with bis(2-aminoethyl)amine (BDA) using the surface grafting approach. The physical and chemical properties of the prepared SBA-15@BDA NPs were determined using a variety of instruments, including small-angle X-ray diffraction (SAXS), Fourier-transform infrared (FTIR), scanning electron microscope (SEM), N2 adsorption-desorption, thermogravimetric, particle size distribution, and zeta potential analysis. The MSN has a large surface area of up to 574m2/g, a pore volume of 0.57cm3/g, and a well-ordered mesoporous nanostructure with an average pore size of 3.6nm. The produced SBA-15@BDA NPs were used to adsorb selectively to lead (Pd2+) ions from an aqueous solution. The adsorption study was performed under various conditions, including the influence of solution pH, adsorbent dose, adsorption kinetics, adsorption selectivity in the presence of competing metal ions, and reusability. The results of the kinetic study demonstrated that SBA-15@BDA NPs absorb selectively Pb2+ ions via chemisorption. The SBA-15@BDA NPs show Pb2+ ions with a maximum adsorption capacity of ~ 88% and an adsorbed quantity of approximately ~ 112mg/g from the studied aqueous solution. The adsorption mechanism relies on coordination bonding between Pb2+ ions and surface-functionalized amine groups on SBA-15@BDA NPs. Furthermore, the proposed SBA-15@BDA NPs adsorbent demonstrated excellent reusability over five cycles without significantly reducing adsorption performance. As a consequence, SBA-15@BDA NPs might serve as an effective adsorbent for the selective removal of Pb2+ ions from aqueous effluent.

New silica-based adsorbents for water purification: Removal of short- and long-chain perfluoroalkyl sulfonic acids (PFSA) at sub-nanomolar concentrations

Perfluoroalkyl acids (PFAAs) are widespread in the aquatic environment and also measurable in ground and drinking water. Because of the insufficient PFAA elimination in conventional water treatment processes, e. g. active carbon based methods, consumers in areas with contaminated water supplies are exposed to an elevated health hazard. For this purpose, the applicability of five differentially fluorinated silica-based adsorbents (HSU00107954-958) to remove the potentially human toxic perfluoroalkyl sulfonic acids(PFSAs) perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS) from water was investigated with regard to removal efficiencies (REs) and equilibrium loadings. During the adsorbent screening at nanomolar concentrations (20.0–33.4 nmol L−1) maximum REs of 46.9% for PFBS (HSU00107954), 79.4% for PFHxS (HSU00107954), and between 86.5 to 96.7% for PFOS (HSU00107956, and HSU00107954, respectively) have been achieved. Even at picomolar concentrations (< 400 pmol L−1) HSU00107954 was still able to eliminate PFBS and PFHxS with an efficiency of 46.3–51.2% and 79.1–88.2%, respectively. Analyses of the equilibrium loadings of the functionalized adsorbents in the concentration range 40.1 pmol to 3.34 nmol L−1 resulted in appropriate linearized Freundlich isotherms for all investigated PFSA. Compared to literature-based Freundlich adsorption coefficients (KF) for granular activated carbon (GAC), the determined KF values (nmol(1−n) Ln m−2) of the most efficient adsorbents HSU00107956 and HSU00107954 for each PFSA were significantly 8–10 and 50–60 times higher, respectively. These proven increased adsorption capacities relative to activated carbon possibly indicate specific PFSA selectivities of the functionalized macroporous silica adsorbents.

Purge and Trap Extraction of Musty Odor Compounds by Thermal Desorption Tube Packed with Polydimethylsiloxane-Coated Macroporous Silica Adsorbent

Purge and Trap Extraction of Musty Odor Compounds by Thermal Desorption Tube Packed with Polydimethylsiloxane-Coated Macroporous Silica Adsorbent

Competitive Adsorption of Aqueous Cd(II) and Pb(II) Solutions onto Silicas Synthesized with Saponin as Template Agent

The aim of the research was to prepare silica adsorbents using an environmentally friendly pathway, a template synthesis with saponin biosurfactant as a structure-directing agent. The adsorbents prepared in this way exhibit improved adsorption properties while maintaining environmental innocuousness. For the preparation of porous silica, the biosurfactant template sol–gel method was used with tetraethoxysilane as a silica precursor. The silica adsorbents were analyzed by FTIR spectroscopy, nitrogen adsorption–desorption and SEM/EDX microscopy, TEM/HRTEM microscopy, and thermogravimetric analyses. Batch tests were carried out to remediate Pb(II)/Cd(II) ions in single/binary aqueous solutions, and the effect of the surfactant on the adsorption properties was assessed. The optimal adsorption parameters (pH, contact time, initial concentration of metal ions) have been determined. The adsorption was fitted using Langmuir and Freundlich adsorption isotherms and kinetic models. Mathematical modeling of the retention process of Pb(II) and Cd(II) ions from binary solutions indicated a competitive effect of each of the two adsorbed metal ions. The experimental results demonstrated that saponin has the effect of modifying the silica structure through the formation of pores, which are involved in the retention of metal ions from aqueous solutions and wastewater.

Performance of the silica adsorbent from snake fruit peel for removing heavy metals of Ag, Cu, Mn, and Cr in SCW

Silver crafts wastewater (SCW) typically contains environmentally harmful heavy metals, including Ag, Cu, Mn, and Cr, necessitating treatment before disposal. This study explores a promising solution using silica (SiO2) adsorbents derived from snake fruit peel through acidic activation with HCl concentrations of 2, 4, and 6 M. Qualitative analysis of the adsorbent involved Fourier-transform infrared spectrometer (FTIR) and x-ray fluorescence (XRF) techniques. XRF analysis revealed major compositions of Si (26%) and Cl (71.46%), with minor elements such as Ca (0.91%), P (0.42%), K (0.37%), Fe (0.12%), and others. FTIR analysis indicated the presence of siloxane (Si-O-Si) and silanol (Si-OH) on the adsorbent. The SiO2 adsorbent demonstrated effectiveness in removing heavy metals (Ag, Cu, Mn, and Cr) from SCW, achieving removal percentages of approximately 16.96%, 24.38%, 19.34%, and 9.82%, respectively. This research contributes to the development of an environmentally friendly approach for SCW treatment using silica adsorbents derived from agricultural waste.

Experimental Study on the Gelling Properties of Nano-Silica Sol and Its Spontaneous Imbibition Grouting Mudstone

The low-permeability argillaceous rock mass is an unfavorable geological body commonly found in the construction process of underground engineering conditions such as roadways and tunnels. Due to the compact structure and low permeability of the rock mass, grouting with conventional materials cannot effectively seal the micro-cracks of the rock mass. Based on the low efficiency of high-pressure grouting of nano-silica sol, this paper preliminarily explores the regularities and mechanism of grouting and pore sealing of low-permeability rock mass under the action of silica sol imbibition from the aspects of gelling properties of silica sol, core pore structure, imbibition law, and pore sealing characteristics. The results show the following: (1) The increase in particle size during the gel process reduced the injectability and wettability of the silica sol. The imbibition properties of silica sol were time-varying, and the deterioration inflection points of injectability and wettability appeared at 10 h and 9 h, respectively. (2) Catalyst, temperature, gel process, and rock mass permeability will affect the law of core imbibition, and the injectability and capillary force of the grouting material and rock mass will jointly affect the imbibition process of silica sol. (3) Silica sol imbibition changed the pore size distribution of the core, the pore volume above 50 nm decreased, and the pore volume below 50 nm increased. Silica sol has multiple effects such as filling, adsorption, and percolation in the imbibition process of the micro-pores of rock mass, and the adsorption and percolation of silica are related to the nano micro-pores.

Adsorption of Fluoride from Water Using Aluminum-Coated Silica Adsorbents: Comparison of Silica Sand and Microcrystalline Silica

Two aluminum-coated silica adsorbents were evaluated using silica sand and microcrystalline silica as aluminum-oxide-based adsorbents with different crystalline silica base materials. The aluminum coating contained mainly amorphous aluminum oxides for both aluminum-coated silica adsorbents. The adsorption of fluoride onto both adsorbents was favorable according to the Langmuir and Freundlich adsorption equations, while the physical adsorption of fluoride occurred for both adsorbents according to the Dubinin–Raduskevish (D-R) equation. The adsorption of fluoride was stronger for aluminum-coated silica sand based on adsorption parameters from the Langmuir, Freundlich, and D-R adsorption equations, with the stronger binding of fluoride likely due to the observed greater specific adsorption. The adsorption capacity determined using the Langmuir equation was about 7 times greater for aluminum-coated microcrystalline silica primarily due to the 1.22-orders-of-magnitude-larger surface area of aluminum-coated microcrystalline silica, whereas the surface-normalized adsorption capacity was 2.4 times greater for aluminum-coated silica sand, possibly due to more aluminum being present on the surface of silica sand. Fluoride adsorption occurred over a broad pH range from 3 to 10 for both adsorbents, with nearly the same pHPZC of 9.6, while aluminum-coated microcrystalline silica displayed a higher selectivity for fluoride adsorption from different natural water sources.

Unlocking Heavy Metal Remediation Potential: A Review of Cellulose–Silica Composites

This comprehensive review explores recent advancements in heavy metal remediation techniques, focusing on the utilization of cellulose–silica composites and tailored surface modification techniques. We examine the synthesis strategies and properties of cellulose–silica adsorbents, highlighting their enhanced adsorption capacities and structural robustness for removing heavy metal pollutants from aqueous environments. The review investigates various surface modification approaches, including thiol functionalization, amino acid grafting, and silane coupling agents, for optimizing the surface chemistry and morphology of cellulose–silica composites. Mechanistic insights into the adsorption processes and kinetics of modified adsorbents are discussed, along with considerations for optimizing adsorption performance under different environmental conditions. This review provides valuable perspectives on the development of effective adsorbent materials for sustainable heavy metal remediation applications.

Pemanfaatan Lumpur Lapindo sebagai Sumber Silika Magnetik untuk Adsorpsi Tumpahan Crude Palm Oil

In this paper, synthesis of silica magnetite adsorbent has been carried out from Lapindo Mud silica and magnetite (Fe3O4) using the template Cetyltrimethylammonium bromide (CTAB) through a microemulsion process. This research aims to determine the adsorption ability of magnetic silica material as an adsorbent for Crude Palm Oil (CPO) with varying contact times of 10, 20, 30, 60, 90 minutes and an adsorbate concentration of 0,2, 0,4, 0,6, 0,8 and 1 gram. Silica is obtained from Lapindo Mud extraction using the acid leaching method using HCl. Magnetite was prepared by mixing ferric chloride and ferrous chloride salts with an alkaline base. Synthesis of magnetic silica adsorbent using CTAB and 1-butanol as a surfactant and co-surfactant, respectively. The characterization results from FTIR and SEM-EDX data identified the presence of silanol (Si-OH) and Fe-O groups, magnetic silica adsorbent showed an irregular morphological pattern, the size tended to be heterogeneous, contained Fe, O and Si elements. The XRD results show that there are peaks in the (200), (311) and (440) planes, the GSA results show that the pore surface area is 37.048 m2/g, the total pore volume is 0.321 cm3/g and the pore diameter is 33.907 nm, which indicates that the pores have a mesoporous structure. Based on this research, the optimum contact time is 60 minutes with adsorption kinetics following the pseudo-second order and Langmuir isotherm with an adsorption capacity of 1.76 mg/g.

Encapsulation of iodine-loaded adsorbents in blended Portland cement and geopolymer wasteforms

Capture of radioiodine by solid adsorbents and subsequent cementation is a promising solution to achieve “Near Zero” emissions from nuclear fuel cycles. We investigate cementation of iodine-loaded silica adsorbents in blast furnace slag blended Portland cement (BFS:PC) and metakaolin-based geopolymers, and subsequent leaching in deionised water. Adsorbent encapsulation retarded BFS:PC hydration, but not geopolymer reaction. Phase assemblage was unaffected by adsorbent encapsulation for both BFS:PC and geopolymers, which comprised calcium aluminosilicate hydrate and potassium aluminosilicate hydrate gels, respectively. Adsorbents were encapsulated intact within BFS:PC, whereas adsorbents dissolved in the high pH of fresh geopolymers. BFS:PC exhibited low leaching stability and an alteration layer, however minimal iodine leaching occurred due to intact absorbents. Geopolymers showed high leaching stability, however adsorbent degradation resulted in significant iodine leaching. This evidences potential for cementation of radioiodine-loaded adsorbents under mild conditions, and highlights the importance of synergy when designing adsorbents and wasteforms for radioiodine abatement.

Synthesis of amine-pillar[5]arene porous adsorbent for adsorption of CO2 and selectivity over N2 and CH4

A novel amine-modified pillar[5]arene bonded porous silica adsorbent (DETA-P5S) was designed to be applied to dynamic CO2 adsorption and selective separation of CO2 over N2 and CH4 gases mixture. The results demonstrated that reasonable introduction of DETA into the BE-P5 bonded silica support has significantly increased the adsorption capacity of CO2. The DETA-P5S has the optimal adsorption capacity of 9.1 mmol/g with 5 vol% CO2 at 40 °C. The main reason of this increased capacity could be attributed to the enhanced CO2 diffusion into porous adsorbent for its better dispersion in the pores of amine-pillar[5]arene cavity and active site of DETA. Furthermore, the dynamic saturation adsorption capacities of DETA-P5S were 7.11 (0.37) and 6.18 (0.44) mmol/g for CO2/N2 and CO2/CH4, respectively, both the gas mixtures showed high separation selectivity. Simultaneously, the DETA-P5S can maintain outstanding CO2 adsorption capacity after fifteen regeneration cycles. Consequently, the designed DETA-P5S could serve as a promising adsorbent for CO2 capture and storage.

Correction: Hasan et al. Synthesizing and Characterizing a Mesoporous Silica Adsorbent for Post-Combustion CO2 Capture in a Fixed-Bed System. Catalysts 2023, 13, 1267

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