Silica Gel Research Articles

Isolation, Development and Validation of Chromatographic Methods for the Estimation of Linoleic Acid from Different Parts of Euphorbia Neriifolia Linn.

Objectives: This is the first report on the development and validation of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC)-densitometric methods for the identification of linoleic acid (LA) in petroleum ether extract (PEE) of Euphorbia neriifolia (EN) stem (ST), latex (LX), and bark (BA). Methodology: Chromatographic analyses were performed on silica gel-G and silica gel 60 F254 plates and the antioxidant activities of isolated compounds were investigated by 2,2-diphenyl-1- picrylhydrazyl (DPPH) spectrophotometric assay. Results: The chromatographic analyses revealed better spots and well-separated peaks of LA with retention factor (Rf) values at 0.54 (ST), 0.40 (LX), and 0.64 (BA), respectively. The linearity of the calibration curve ranges from 10-50 ng/spot (ST), 10-100 ng/spot (LX), and 50-200 ng/spot (BA). The proposed method was characterized by better accuracy, better robustness, and good precision, ranging from 0.173 to 0.372% (intra-day) and 0.185 to 0.205% (inter-day). The value of the limit of detection and quantification equal to 1.04 and 3.16 ng/spot in ST, 0.87 and 2.64 ng/spot in LX, and 0.177 and 0.53 ng/spot in BA determined the sensitivity of the method. In the obtained chromatogram, no peak was observed other than the LA which determined the specificity of the method. The % RSD of < 2% after periods of 12, 24, 36, 48, and 72 h determined the stability of standard LA. Conclusion: Thus, the fingerprinting method is valuable in determining the adulterants and in routine quality control of formulations and herbal drugs.

Experimental Evidence for Zerovalent Pd(NHC) as a Competent Catalyst in C-N Cross-Coupling (NHC = DiMeIHeptCl).

Use of the branched N-heterocyclic carbene (NHC) ligand 1,3-bis(2,6-bis(3-methyl-1-(2-methylpropyl)butyl)phenyl)-4,5-dichloro-1,3-dihydro-2H-imidazole-2-ylidene (DiMeIHeptCl) facilitated the stabilization of several relevant intermediates for Pd(NHC)-catalyzed C-N cross-coupling reactions. Complexes [Pd(DiMeIHeptCl)]2(μ-N2), [Pd(DiMeIHeptCl)]2(μ-η2-1,2-η2-4,5-C6H6), and Pd(DiMeIHeptCl)(pyridine), representing zerovalent Pd(NHC) bearing labile ligands, were isolated and structurally characterized, along with divalent PdCl(Ph)(DiMeIHeptCl) and PdCl(Ph)(DiMeIHeptCl)(n-propylamine). The former is a 14-electron Pd complex, which is stable under air and chromatography on silica gel or neutral alumina. One possible reason for this exceptional stability is the numerous dispersion interactions between the NHC alkyl chains and the Pd-Ph group. Detailed investigations of catalyst activation and oxidative addition confirmed that "Pd(NHC)" is formed from many known Pd(II)(NHC) precatalysts and provided activation rates for these different precatalysts.

Revealing the backbone structures of land-based fulvic acids derived from river and soil through n-butylsilane reduction.

While ultra-high-resolution mass spectrometry has enabled the identification of the molecular composition of dissolved organic matter (DOM), elucidating its molecular structure remains a challenging endeavor. Here, two fulvic acids (FAs), one from river and the other from forest soil, were subjected to reduction using an optimized n-butylsilane (n-BS) reduction method. The reduction products were purified through a combination of liquid-liquid extraction and silica gel column chromatography, resulting in the separation into saturates, aromatics, and polar products. The polar products were analyzed by high-resolution mass spectrometry (HRMS), and the saturates and aromatics were analyzed using gas chromatography-mass spectrometry (GC-MS). HRMS results showed that the number of oxygen atoms and double-bond equivalent (DBE) values of FA decreased after reduction. GC-MS results revealed that a total of 270 hydrocarbon monomers were identified from the reduction products of a single sample, with the highest carbon number of cycloalkanes reaching C33. For the first time, steranes and hopanes were detected in the reduction products, potentially serving as evidence for the existence of carboxyl-rich alicyclic molecule (CRAM) precursors. Additionally, a significant number of polycyclic aromatic hydrocarbons were identified, and the potential sources of various compounds were preliminarily inferred based on their isomers. This study extends the knowledge of the possible backbone structure of the DOM and provides a new potential tool for investigating the origin and transformation mechanisms of DOM.

Green and Sensitive Analysis of the Antihistaminic Drug Pheniramine Maleate and Its Main Toxic Impurity Using UPLC and TLC Methods, Blueness Assessment, and Greenness Assessments

For the first time, two direct and eco-friendly chromatographic approaches were adapted for the simultaneous estimation of pheniramine maleate (PAM) and its major toxic impurity, 2-benzyl pyridine (BNZ). Method A used reversed-phase ultra-performance liquid chromatography; separation was achieved within 4 min using a C18 column with a developing system of methanol/water (60:40 v/v) with a 0.1 mL/min flow rate. Photodiode array detection was adjusted at 215 nm. The method was linear in the ranges of 5.0–70.0 and 0.05–10.0 µg/mL for PAM and BNZ, correspondingly. Method B used thin-layer chromatography; separation was applied on silica gel TLC F254 using ethanol/ethyl acetate/liquid ammonia (8:2:0.1, in volumes) at room temperature, at 265 nm. Linearity was assured at concentration ranges 0.5–8.0 and 0.1–3.0 µg/band for the two components, respectively. Generally, the new UPLC and TLC methods outperform the old ones in terms of quickness, greenness, and sensitivity. Concisely, the greenness features were partially achieved using the Green Analytical Procedure Index (GAPI) and the Analytical Greenness (AGREE) pictograms. In contrast, the usefulness of the novel approaches was assured via the Blue Applicability Grade Index (BAGI) tool.

Double-Chamber Underwater Thruster Diaphragm with Flexible Displacement Detection Function.

The purpose of this paper is to develop a self-detecting diaphragm integrated with a flexible sensor, which is utilized in an underwater thruster. Resistive strain sensors are easy to manufacture and integrate due to their advantages in reliable stretchability and ductility. Inspired by the structure of neurons, we fabricated resistive flexible sensors using silica gel as the matrix with carbon black and carbon nanotubes as additives. All fabricated sensors demonstrated positive resistance characteristics under 60% strain conditions, with the sensor containing a mass ratio of 9 wt % carbon black and carbon nanotubes exhibiting the best resistance-strain linearity. To verify the anti-interference capability of sensors with silica gel substrates of varying hardness values under changing environmental pressure, we tested the pressure sensitivity of the sensors by altering the hardness of the silica gel. The results indicate that silica gel with the highest hardness value provides the best resistance to environmental pressure interference. To detect the motion and deformation of the internal functional components of the thruster, we combined strain detection with the movement operation function of a silica gel diaphragm, resulting in a new integrated diaphragm with sensor detection capabilities. The integrated diaphragm was evaluated by using a tensile testing machine and an LCR tester. The results demonstrate that the mechanical properties of the diaphragm are stable, exhibiting reliable resistance characteristics and a sensitive response during underwater operation. This research can also be applied to the detection of motion amplitudes of other types of soft robots.

Silicon Ameliorants from Serpentine-containing Mining Waste

The results of research aimed at developing a method for using serpentine-containing mining waste as silicon ameliorants are presented. The effect of introducing the initial and thermally activated serpentine mineral lizardite and silica gel into peat soil on the chemical composition of plants was studied. The effectiveness of materials as a source of silicon for plants was determined. It was concluded that serpentines affect soil processes in a similar way to traditional silicon preparations, which makes it possible to utilize serpentine-containing mining waste as silicon ameliorants.

High Performance Thin Layer Chromatographic Method for Simultaneous Estimation of Vitamin C, Thymoquinone and Thymol in Plant Extracts

Background: Lack of an effective HPTLC simultaneous estimation method for vitamin C, thymoquinone and thymol in plant extracts. Aim: The present study involves the development of an accurate, precise, specific, and specific HPTLC method for the identification and quantification of three phytomarkers thymol and thymoquinone in Nigella sativa (kali jiri) seed extract and vitamin C in Hylocereus polyrhizus (dragon fruit) extract. Methods: Using an aluminum plate pre-coated with silica gel 60 F254 and methanol-n hexane-ammonia (15%) (8.5:1.5:0.2 v/v/v) as the mobile phase, thin layer chromatographic development was performed. Results: For each of the three markers, densitometric quantification was carried out at the isobestic point of 271 nm. Vitamin C, thymol, and thymoquinone bands were separated chromatographically at Rf values of 0.66, 0.35, and 0.19, respectively, by using developed mobile phase. For thymol, thymoquinone, and vitamin C, linearity range was 2000-8000 ng/band. The three markers showed 99.39%–99.91% recovery for thymol, 99.22%–99.89% recovery for thymoquinone, and 99.19%–99.69% recovery for vitamin C. Conclusion: The optimized method was used to quantify three thymol and thymoquinone in N. sativa (kali jiri) seed extract and vitamin C in H. polyrhizus (dragon fruit) extract.

Trialkoxysilane Grafting in Alcohols: A Simple Approach towards Modified Silica-Based Materials.

The grafting of trialkoxysilanes is the most common method for the surface functionalization of silica gel, and it is usually carried out in the presence of toluene or other solvents such as acetonitrile or acetone. Here, we replaced these solvents with alcohols to afford silica materials containing alkoxy groups linked to the silicon atom. The grafting of N,N-dimethyl-3-amino- or 3-amino-propyltrimethoxysilane was carried out in the presence of several alcohols containing an unsubstituted alkyl chain (C7 and C14), a PEG functionalized chain, or an amino-substituted chain (N,N-dimethylamino, pyridyl). Materials were characterized via solid-state 13C- and 29Si CPMAS NMR and thermogravimetric analysis to prove that alcohols are not "innocent" solvents but take part in the reaction and lead to [RSi(OR1)-(OSi)2] systems where the OR1 group proceeds from the alcohol used in the synthesis. As a proof of concept, we briefly studied the catalytic activity of some of these materials with the aim of showing how different modifications can influence the course of a selected reaction. Finally, a quaternary ammonium salt (QAS)-based silica was prepared containing both an alkyl-QAS and an alkoxy-QAS linked to silicon atoms. This could represent an interesting approach for the development of new antifouling-based materials and, overall, the described strategy could be useful for the preparation of new organosilica materials.

Stability Indicating HPTLC Method for Estimation of Cubebin in Crude Drug and Marketed Formulations

Background: Cubebin is a naturally occurring lactone lignan isolated from the plant species Piper cubeba. It exhibits a range of biological activities, including anti-inflammatory, antimicrobial, and anticancer properties. This compound has garnered significant interest for its potential therapeutic applications in traditional and modern medicine. Aim: This study aimed to develop a novel stability-indicating High-Performance Thin Layer Chromatography (HPTLC) technique that is simple yet precise in estimating cubebin in crude drug and marketed formulations. Method: Cubebin was estimated using precoated TLC silica gel 60 F254 plate as a stationary phase and n-hexane: ethyl acetate: formic acid: methanol (6:3.5:0.5:0.3 v/v/v/v) as a mobile phase with the chamber saturation time of 20 mins. Key Findings: Cubebin was detected and quantified at the wavelength of 283nm. The Rf value of cubebin in standard solution, Piper cubeba extract, Dhanwantari Vati, and Khadiradi Vati was found to be 0.494±0.0015, 0.492±0.002, 0.490±0.0020, 0.499±0.001 respectively. The calibration curve exhibited linearity within the range of 3000-13000 ng per band with a correlation coefficient (r2) of Cubebin was 0.9968. The method developed was utilized for the quantitation of cubebin in Piper cubeba and both the marketed formulations. Conclusion: A novel HPTLC method was developed and validated in accordance to ICH guidelines for the analysis of cubebin in crude drug and marketed formulations. The method was found to be simple, precise, accurate, and specific. This method is suitable for quality control and stability testing of cubebin-containing formulations.

Fracture characteristics and microscopic mechanism of slag-based marine geopolymer mortar prepared with seawater and sea-sand

This study utilized seawater, sea sand, and ternary solid waste to produce marine geopolymer mortar (MGM). 23 groups of MGM samples with varying alkali content and basalt fiber (BF) and polypropylene fiber (PPF) volume fractions, as well as marine cement mortar (MCM), were tested for fracture characteristics. Three initial crack length ratios (a0/h) (0.2, 0.3, and 0.4) were designed. The analysis included load-crack mouth opening displacement (P-CMOD) curves for all specimens, focusing on critical crack length (ac), critical crack tip opening displacement (CTODc), fracture toughness (KSIC), fracture energy (GF), and facture brittleness index (FBI). Results indicated that increasing alkali content enhanced strength and elastic modulus, peak fracture load, critical crack extension length (Δac), and CTODc, while decreasing final CMOD. This was attributed to the increased alkali content, which enhanced the mortar’s density. However, excessive alkali content also led to increased shrinkage damage within the matrix, making it prone to stress concentrations and resulting in brittle failure. Based on the research, it is recommended that the alkali content be controlled within the range of 4–5 %. Hybrid fibers showed superior overall toughness enhancement, increasing KSIC, GF, and FBI by 54.3 %, 95.6 %, and 427.4 %, respectively. This improvement was due to the synergistic effect of BF and PPF, which increased the specimen’s elastic modulus, reduced crack propagation speed, and sustained load-bearing capacity during the later stages of crack development. The fracture toughness of conventional geopolymer mortar was positively correlated with the Ca/Si ratio and was lower than that of MGM. In contrast, MGM’s Ca/Si ratio showed an inverse correlation with KSIC, indicating that phase assemblage governs the fracture resistance of MGM. This is because Cl- in seawater intensified geopolymerization reactions. Interwoven gel structures in MGM, with surface depositions like magnesium aluminosilicate hydrate (M-A-S-H), magnesium silicate hydrate (M-S-H), and silica gel, filled pores, and improved homogeneity, resulting in its superior fracture toughness over conventional geopolymer mortar.

Silica Gel Supported Solid Amine Sorbents for CO2 Capture

Silica Gel Supported Solid Amine Sorbents for <scp>CO₂</scp> Capture

Characterization of Potent Odorants Causing an Oily Odor in Rice-Made Baijiu by Comparative Aroma Extract Dilution Analysis, Quantitative Measurements, and Aroma Addition and Omission Studies.

The presence of an oily odor in rice-made Baijiu is a unique characteristic that has not been thoroughly studied. This study qualitatively and quantitatively identified important aroma-active compounds in samples with typical and atypical oily odors using aroma extract dilution analysis (AEDA). By comparing the differences between flavor dilution (FD) and odor activity values (OAVs), nine compounds showing significant differences were selected. By combining normal-phase silica gel column and sensory analysis, these nine potential oily odor compounds were isolated from the typical oily odor sample. Addition and omission experiments confirmed that hexanal, trans-2-heptenal, trans,trans-2,4-nonadienal, (2E)-2-decenal, trans,trans-2,4-decadienal, and γ-nonanolide are key contributors to the oily odor.

Exploring the Antibacterial and Antiparasitic Activity of Phenylaminonaphthoquinones-Green Synthesis, Biological Evaluation and Computational Study.

Organic compounds with antibacterial and antiparasitic properties are gaining significance for biomedical applications. This study focuses on the solvent-free synthesis (green synthesis) of 1,4-naphthoquinone or 2,3-dichloro-1,4-naphthoquinone with different phenylamines using silica gel as an acid solid support. The study also includes in silico PASS predictions and the discovery of antibacterial and antiparasitic properties of phenylaminonaphthoquinone derivatives 1-12, which can be further applied in drug discovery and development. These activities were discussed in terms of molecular descriptors such as hydrophobicity, molar refractivity, and half-wave potentials. The in vitro antimicrobial potential of the synthesized compounds 1-12 was evaluated against a panel of six bacterial strains (three Gram-positive: Staphylococcus aureus, Proteus mirabilis, and Enterococcus faecalis; and three Gram-negative bacteria: Escherichia coli, Salmonella typhimurium, and Klebsiella pneumoniae). Six compounds (1, 3, 5, 7, 10, and 11) showed better activity toward S. aureus with MIC values between 3.2 and 5.7 μg/mL compared to cefazolin (MIC = 4.2 μg/mL) and cefotaxime (MIC = 8.9 μg/mL), two cephalosporin antibiotics. Regarding in vitro antiplasmodial activity, compounds 1 and 3 were the most active against the Plasmodium falciparum strain 3D7 (chloroquine-sensitive), displaying IC50 values of 0.16 and 0.0049 μg/mL, respectively, compared to chloroquine (0.33 μg/mL). In strain FCR-3 (chloroquine-resistant), most of the compounds showed good activity, with compounds 3 (0.12 μg/mL) and 11 (0.55 μg/mL) being particularly noteworthy. Additionally, docking studies were used to better rationalize the action and prediction of the binding modes of these compounds. Finally, absorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions were performed.

Modified culture media development using locally available fertilizers and vitamin supplements for continuous mass culture of Chaetoceros gracilis

Microalgae culture is a vital nutritional resource for hatchery development in aquaculture and has gained significant interest as a sustainable food ingredient, versatile feedstock for biofuels, with broad industrial applications. The high cost of microalgae culture media hinders mass production, necessitating the development of affordable, simpler alternatives for commercial viability. The aim of this study was to develop a modified culture media for Chaetoceros gracilis utilizing locally available fertilizers and vitamins. In the first experiment, the cell density of C. gracilis across four fertilizers combinations (T1, T2, T3 and T4) with three replicates was evaluated to identify the best performing fertilizers recipe. The significantly higher cell density was observed in T1, where a combination of urea, TSP, mineral mix, EDTA, silicate gel, NPK, compost were used, than the other treatments where one or more ingredients were missing. The growth curve showed that with 1 ml/L fertilizers combination of T1 cell density peaked (21.8×10^5 cell/ml) at day three with the death phase starting at day 04. In the second experiment, the effect of vitamin addition was evaluated with T1 considering as control (V0-without vitamin supplement) and, the Multivitamin-Zinc B and Neobion addition with T1 as treatment V1 and V2, respectively. While Neobion addition significantly increased cell density, multivitamin-Zinc B addition reduced the cell density. Finally, the potentiality of continuous culture of C. gracilis with the modified fertilizer media (V2) was evaluated. The cell density in 300 L tank culture starting from 6.6×10^5 cell/ml peaked 23.8 ×10^5 cell/ml at day two and remained relatively static until investigation finished with the supplement of V2 media two days interval. The present study suggest that development of modified fertilizer media using affordable, locally sourced ingredients for algae cultivation in the hatcheries and aquaculture industry could create an alternative to relying on pure laboratory-grade media.

Electrospun hybrid microfibers for desiccant cooling/air dehumidification

The aim of this work was to assess the efficiency and suitability of hybrid adsorbent microfibers, produced by the electrospinning technique, in open-cycle adsorption applications, such as desiccant cooling, air dehumidification/humidification and heat storage, requiring high water adsorption capacity and high stability at high relative humidity, up to 80 %. Specifically, silica gel (SG) and magnesium sulfate (MS) as adsorbents and polyacrylonitrile (PAN) as polymer carrier, were used to prepare the hybrid microfibers at different concentrations of adsorbents and tested under isothermal conditions (50 °C) with relative humidity increasing from 0 % to 90 %. Characterization included morphological, structural, and thermal analyses, as well as measurement of ad/desorption isotherms and cyclic hydrothermal stability. The adsorption performances of the SG microfibers were comparable to that of the pure adsorbent: the microfibers with 50 w% silica gel showed a water absorption of 26.1 w% at 80 % relative humidity and T = 50 °C, which was in agreement with the content of SG. Under the same conditions, PAN microfibers with 50 w% MS achieved a water absorption of 42.7 w%. The dispersion of MS crystals in the microfibers improved the stability of the salt to hydration, allowing for a significant enhancement in the adsorption performance of magnesium sulfate.

CO2 Capture via Adsorption Using Silica Gel

This paper investigates the potential of silica gel as an effective adsorbent for CO2 capture. The study explores the adsorption mechanisms, the efficiency of CO2 uptake, and some factors influencing the adsorption capacity of silica gel. The experimental results demonstrate the significant potential of silica gel for CO2 adsorption under various conditions. The adsorption capacity was found to be highly dependent on parameters such as gas flow rate and the particle size of silica gel. The findings suggest that with optimized conditions, silica gel could be a viable material for reducing atmospheric CO2 levels. This research contributes to the development of sustainable and efficient technologies for mitigating climate change through carbon dioxide capture and storage. Keywords: CO2 capture, adsorption, efficiency, silica gel

Preparation of modified silica gel supported silver nanoparticles and its evaluation using zone of inhibition for water disinfection

In this work, preparation of modified silica gel supported silver nanoparticles and its evaluation using zone of inhibition for water disinfection were investigated. The silica contents of the teff straw [TS] and teff straw ash [TSA] are 5.92 and 92.21 %, respectively. The calcinated TS ash at 700 °C was mixed with NaOH solution. The solution is then neutralized with HCl solution and then gel formation using the sol gel method. The silica gel yield was recorded and characterized. The SG with major silica functional group, amorphous structure, high porosity from the morphology, high surface area of 807.163 m2/g, pore volume of 0.34 cm3/g, pore diameter of 1.70 nm and silica gel purity of 99.39 % were achieved at a calcination temperature of 700 °C. It is then; further modified using trimethylchlorosilane (TMCS)/ethanol/hexane at different volumetric ratio and the resulting product is modified silica gel (MSG). MSG has excellent hydrophobic properties that have been required during water treatment. In this method, MSG with a major silica functional group, well ordered structure due to the TMCS modifier, maximum surface area of 510.40 m2/g was achieved at volumetric ratio of 0.25:0.25:1 of TMCS/ethanol/hexane, respectively. Then, MSG supported AgNPs (MSG-AgNPs) was prepared by mixing different concentrations of AgNPs-MSG and characterized. The MSG-AgNPs have shown AgNPs on the surface of MSG from the EDX result, different absorbance, pore from the morphology, with a maximum surface area of 475.0 m2/g was obtained at 1.5 mM of AgNPs concentrations. The performance of MSG-AgNPs was evaluated using zone of inhibition measurement and batch disinfection studies against E. coli and S. aureus. At 1.5 x 108 CFU/mL initial bacterial concentrations, the maximum inhibition zone diameter was 12.80 and 14.30 mm for E. coli and S. aureus, respectively.

Comparison of Microwave Adsorpsion of Core-Shell Fe3O4@SiO2 by Different Methods

Abstract In this research, magnetite nanoparticles coated with sillica from rice husk ash (core-shell Fe3O4@SiO2) were synthesized by a modified stöber method through hydrolisis of silica using basic catalyst. Phase composition, morphology and microstructure were characterized using XRD, SEM, and TEM. The result shows that the sillica shell was successfully coated the core of nanoparticles magnetite. Core-shell Fe3O4@SiO2were synthesized using two method, first silica extraction and second through the silica gel. The application on microwave absorption are measured using VNA at the X-band frequency (8-12 GHz). Materials reach a reflection loss value of -34,29 dB at a frequency of 10,98 GHz for the first method (extraction of silica). For the second method (through silica gel), it exhibits two maximum absorptions with a reflection loss value under -20 dB, which are -23,05 dB at a frequency of 10,1 GHz and -25,03 dB at a frequency of 10,98 dB.

Modeling of bed-to-wall heat transfer coefficient in fluidized adsorption bed by gene expression programming approach

Adsorption cooling and desalination methods with adsorption chillers (AC) are promising in energy technologies. However, the low-performance coefficient and bulkiness of traditional packed-bed ACs, primarily due to the high voidage of the sorbent beds leading to low heat transfer coefficients, pose significant challenges. Despite numerous attempts, a practical solution to this problem is yet to be found.In response to this challenge, we propose a novel approach: a fluidized adsorbent bed instead of the traditional packed bed. We also introduce gene expression programming (GEP) as an innovative artificial intelligence (AI) method for modeling the bed-to-wall heat transfer coefficient in the adsorption bed. Our study includes calculations and model validation for a heat transfer adsorption bed reactor designed for low-pressure adsorption processes. The fluidizing agent of the adsorbent bed was water vapor generated in the evaporator. Silica gel was used as the parent adsorption material in our tests. The heat transfer coefficient was successfully validated and determined through experiments and estimated using the formulated (b-t-wHTc) meta-model. The data evaluated by the model aligns well with the experimental results. Our calculations demonstrate that the GEP-based model accurately predicts the heat transfer coefficient and is suitable for analyzing the fluidized adsorption bed reactor.The outlined studies serve as a benchmark for subsequent simulations of the intensified heat transfer adsorption bed reactor, as they are integral to project No. 2018/29/B/ST8/00442, titled “Research on sorption process intensification methods in modified construction of adsorbent beds,” supported by the National Science Center in Poland.

Material-level experimental study on utilising ionic liquid/graphene composites for sorption heat storage

Sorption heat storage technology has recently sparked an increasing interest because of its advanced heat storage capabilities. However, material-level heat and mass transfer challenges persist. This work contributes to the field by the development of new sorption composite materials that are comprised ionic liquids (1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium chloride) impregnated in 1–5 2D-layered graphene host matrix. Their sorption, heat transfer, heat storage, and charging/discharging rate properties were experimentally investigated using both water and ethanol as adsorbates. The adsorption isotherms and kinetics for both the adsorbates onto the developed composites and the parent ionic liquids were experimentally measured at different temperatures. The isosteric heat of adsorption for all the studied pairs was determined using the Clausius-Clapeyron method, showing an increasing trend with an increasing uptake. They showed that the specific heat storage capacity reached 187.5 kJ/kg when water was used as the working sorption agent. The corresponding heat charging/discharging rates are significantly higher, 69 %-78 %, than pure ionic liquids. Compared to silica gel as a baseline sorbent, ionic liquid-graphene composites’ heat storage and transfer capacities are higher by three orders of magnitude. The thermal diffusivities of the developed composites were significantly higher than the baseline silica gel. These innovative sorption composites show great potential for improving thermal energy storage efficiency, making them suitable for applications in renewable energy systems, industrial processes, waste heat recovery, and climate control solutions. However, the developed composites achieved inferior performance compared to the silica gel baseline sorbent when using ethanol as a working fluid to utilise sub-zero ambient air as a heat source because of the relatively larger molecular size of ethanol.