Adsorption Capacity Of Silica Gel Research Articles

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

Optimasi Adsorpsi Ion Tembaga (II) Menggunakan Silika Gel-GPTMS Termodifikasi Sulfonat

Adsorption is a process of sorption onto a specific substance that occurs at the surface of a solid material due to intermolecular forces or the penetration of a substance into the solid material surface. Adsorption involves an adsorbent as the sorbent material and an adsorbate as the component being sorbed. Silica gel is a commonly employed adsorbent for the sorption of Cu2+ ions. It is utilized as an adsorbent due to the presence of silanol and siloxane groups, which serve as active sites that can be modified. The modification aims to enhance the adsorption capacity of silica gel for Cu2+ metal ions. In aquatic environments, Cu metal ions are highly toxic to living organisms, posing significant hazards. The modifying compound employed in this study is monosodium salt of 4 – amino – 5 – hydorxy – 2,7 – naphthalenedisulfonic acid. However, prior to the sulfonate compound modification, a linking compound, γ-glycidoxypropyltrimethoxysilane (GPTMS), is required. The purpose of this study was to determine the effect of variations in pH and contact time on the adsorption of Cu2+ metal ions on sulfonate modified silica gel – GPTMS. The modified silica gel was characterized using Fourier-transform infrared (FTIR). The adsorption of Cu2+ ions was characterized by specific surface area (SSA), and the optimal adsorption conditions were determined as pH 4 and contact time of 60 minutes.

Green synthesis of silica gel adsorbents: microwave boosts silanol groups for improved moisture uptake

This research investigates the influence of microwave irradiation on the silanol content and moisture adsorption capacity of silica gel prepared from clear glass waste. Employing a green and efficient microwave-assisted synthesis method, we demonstrate rapid formation of silica gel with enhanced properties. Fourier-transform infrared (FTIR) analysis confirms the presence of silanol (Si-OH) groups on the synthesized gel, with a focus on the characteristic peak at 956.44 cm⁻¹ indicating their abundance. Notably, the peak area of this peak significantly increases with increasing irradiation time (5 to 15 minutes). This translates to a parallel increase in moisture adsorption capacity, rising from 56% to 82%. The enhanced silanol content suggests the potential of microwave-derived silica gel as a high-performance desiccant, as these groups directly contribute to moisture binding. Our findings highlight the promising potential of waste glass valorization via microwave synthesis for developing sustainable and effective moisture adsorbents.

Kinetics of Adsorption Competition of Pb-Cu and Pb-Methylene Blue in Aqueous Solution using Silica Gels from Coal Fly Ash

The present study investigates the removal of Pb2+ using silica gel (SG) in the presence of the Cu2+ (Pb-Cu) and methylene blue (Pb-MB) ion competitor. These pollutants are toxic and harmful to the ecosystem. The presence of the multicomponent pollutants causes more complications to remove from the water system. The adsorptions were examined in a batch system under certain experimental conditions (pH solution system and contact time). Meanwhile, the FTIR spectrophotometer determines the differences adsorption interaction in silica functional groups before and after adsorption. The results showed that the silanol group of silica gel acted as an adsorption site. In the single systems, the adsorption capacity of silica gel follows the order MB > Cu2+ > Pb2+ of around 84.03; 64.81; and 56.88 mg.L−1, respectively. The kinetic adsorptions of both single and binary systems were best fitted to pseudo-second-order models. In the binary solution systems, both adsorption capacity and adsorption rate of each component decreased compared to the single system. The results indicated that the cationic competitors influenced the Pb2+ adsorption, or vice versa, depending on the amount of charge and adsorption affinity.

Reduction of the heat capacity in low-temperature adsorption chillers using thermally conductive polymers as heat exchangers material

Aside from the low adsorption capacity of silica gel, often used in commercially available low-temperature adsorption chillers today, the cooling performance of such chillers is limited due to the high heat capacity of the mostly metal-based heat exchangers. As a completely new approach, thermally conductive polymers have been studied and examined as heat exchanger materials for low temperature adsorption chillers in order to decrease the energy consumption during the adsorption cycle. The modification of polyamide 6, which was chosen as a model polymer in this study, with expanded graphite leads to enhanced thermal part properties for adsorption heat exchangers. Compared to aluminum as the commonly used heat exchanger material, the heat capacity of a chiller can be reduced by 30%, if such a thermally conductive polymer is applied. Moreover, the increased thermal conductivity of the polymer based part leads to no significant limitation in the adsorption kinetic of water used as a refrigerant in adsorption chillers.

Low-temperature regeneration of novel polymeric adsorbent on decamethylcyclopentasiloxane (D5) removal for cost-effective purification of biogases from siloxane

Biogas, a fuel used to generate electricity, contains siloxanes that can damage combustion engines, leading to expensive repairs and service interruptions. Activated charcoal is used to reduce the silicon content. Since siloxanes are difficult to desorb from the material, the adsorbent beds have to be replaced regularly. Thermal swing adsorption (regeneration at 250 °C) using silica gel is an effective method to remove siloxane from biogas. Also, it would be advantageous and cost-effective if the adsorption material could be regenerated easily at a lower temperature. In the present study, a novel polyacrylic acid (PAA)-based polymer adsorbent was studied as a biogas siloxane adsorbent exposed to adsorption/regeneration cycles. At room temperature (25 °C), the D5 adsorption capacity of RPA was 21.55 mg/g adsorbent, which is ∼70% of the adsorption capacity of silica gel. The thermal desorption of siloxane (D5) from the exhausted polymer was more than 95%, which afforded a similar capacity for siloxane (D5) adsorption, at a low regeneration temperature of 80 °C, where no siloxane regeneration was observed using conventional silica gel.

Adsorption of octamethylcyclotetrasiloxane on silica gel for biogas purification

Biogas can be used as a fuel for electricity conversion. However, volatile organic silicon compounds (including siloxanes) in biogas severely damage combustion engines or solid oxide fuel cells. Three adsorbents of different nature were tested for octamethylcyclotetrasiloxane (D4) removal and silica gel (SG) proved to be the most efficient. It was shown that SG adsorption capacity is in the order of 250mgD4/gSG and the adsorbent bed height has little influence on this adsorption capacity. In the presence of water (relative humidity of 70%), the adsorption capacity was lowered by 90% due to competitive effects and preferential adsorption of water. An increase of the temperature of roughly 20°C also lowered the adsorption capacity but the decrease was less than 15%. Moreover, SG regeneration by heating was only partial, probably due to siloxane polymerization on SG.

Analyzing the adsorption of blood plasma components by means of fullerene-containing silica gels and NMR spectroscopy in solids

The results from studying the adsorption of blood plasma components (e.g., protein, triglycerides, cholesterol, and lipoproteins of low and high density) using silica gels modified with fullerene molecules (in the form of C60 or the hydroxylated form of C60(OH) x ) and subjected to hydration (or, alternatively, dehydration) are presented. The conditions for preparing adsorbents that allow us to control the adsorption capacity of silica gel and the selectivity of adsorption toward the components of blood plasma, are revealed. The nature and strength of the interactions of the introduced components (fullerene molecules and water) with functional groups on the silica surface are studied by means of solid state NMR spectroscopy (NMR-SS). Conclusions regarding the nature of the centers that control adsorption are drawn on the basis of NMR-SS spectra in combination with direct measurements of adsorption. The interaction of the oxygen of the hydroxyl group of silica gel with fullerene, leading to the formation of electron-donor complexes of C60-H, C60-OH, or C60-OSi type, is demonstrated by the observed changes in the NMR-SS spectra of silica gels in the presence of fullerene.

Adsorption of triton X-100 on silica gel: effects of temperature and alcohols

Abstract Adsorption of Triton X-100 (TX-100) on silica gel has been studied as a function of temperature (308–328 K) and composition for mixtures of water with ethanol or t-butanol. The adsorption capacity of silica gel for TX-100 decreases with increase in alcohol content. Adsorption isotherms of TX-100 on silica gel are four-region and were analyzed using the ARIAN (adsorption isotherm regional analysis) model. Data in regions 2, 3 and 4 were fitted to the Temkin, bilayer and reverse desorption isotherms, respectively. The results show that adsorption of TX-100 on silica gel in water and alcohol-water binary mixtures occurs mainly through formation of monolayer surface aggregates or low bilayer coverage.

Determination of Volumetric Mass Transfer Coefficient in Fixed Bed Adsorption

This work was conducted to determine the volumetric mass transfer coefficient (Ky.a) infixed bed adsorption using hexane-benzene mixture by adsorption onto a fixed bed of white silica gel. Benzene concentration was measured by gas chromatography. The effect of feed flow rate and initial concentration of benzene in hexane-benzene mixture on the volumetric mass transfer coefficient and on the adsorption capacity of silica gel was investigated.
 In general, the volumetric mass transfer coefficient increases with increasing hexane flow rate, and with increasing initial concentration of benzene in the mixture. The ultimate value of (Ky.a) was at 53 ml/min of hexane flow rate with benzene initial concentration of (6.53 wt. %), and it was (99.4 kg/m3.s).
 The adsorptive capacity of silica gel increases with decreasing hexane flow rate, as with increasing initial concentration of benzene in the mixture. The best adsorptive capacity of the imported silica gel (100 g of imported silica gel yielded 120 ml of benzene-free effluent) was achieved with the grade (1.18-5 mm) in size at a hexane flow rate 15 ml/min.

Regeneration of used frying oils using adsorption processing

AbstractOur study was carried out to improve the quality of used frying oils and to assess the feasibility of recycling by using an adsorption process. Experiments with used frying oils were conducted with a column method using four adsorbents, silica gel, magnesium oxide, activated clay, and aluminum hydroxide gel. Silica gel offered the most effective overall improvement in the quality of used frying oil of the four adsorbents. Although the limiting adsorption capacity of silica gel, as obtained from the Langmuir model, was 219 mg/g for total polar materials (TPM), the experimental maximal adsorption capacity of silica gel for TPM was 337 mg/g. For commercial application, silica gel used in the process must periodically be reactivated. Reactivated silica gel also was effective to some extent in the adsorption process, although the adsorption capacity decreased by 20–50%.

Experimental study of thermal phenomenon in PSA air dehumidification

A bench scale adiabatic PSA apparatus using a pair of vacuum-jacketed columns was constructed to study the non-isothermal effects involved in PSA air dehumidification with silica gel adsorbent. The thermal phenomenon coupled with the operating parameters, including half-cycle time, pressure ratio and velocity ratio of purge to feed, have been investigated systematically. A V-shaped temperature variation with time and a humped axial temperature distribution were observed for long cycle time due to thermal breakthrough. The temperature propagation speed and the local adsorption rate were obtained numerically from the experimental temperature distribution. The temperature propagation speed was greater than that for the mass because of the higher adsorption capacity of silica gel. The cycle time had no relation to the temperature propagation speed. A higher pressure ratio led to a faster temperature propagation, while the maximum temperature rise was almost the same. When the velocity ratio of purge to feed gas was less than 1.0, the desorption could not proceed completely and thus the mass transfer zone dispersed along the column. Recommendations for the design and operation of air drying PSA were also discussed on the basis of the above interpretation.