Adsorption Capacity Of Aerogel Research Articles

Fabrication of poly(itaconic acid)-g-potassium alginate aerogels as eco-friendly biosorbents for removal of cationic dyes

Biosorbents derived from itaconic acid (IA) with abundant carboxyl groups are viewed as ideal materials for the removal of cationic dyes. However, it is still challenging to prepare IA-based biosorbents with satisfactory structural stability and adsorption ability. In this work, a novel poly(itaconic acid)-g-potassium alginate (PIA-g-PA) aerogel was prepared as a biosorbent and was then utilized to remove cationic dyes. The results presented that the as-prepared PIA-g-PA aerogel possessed outstanding adsorption capacities for cationic dyes based on the adsorption mechanism of electrostatic interaction. The adsorption process was well described by the pseudo-second-order model and the Freundlich model. The maximum adsorption capacities of the as-prepared aerogel toward methylene blue (MEB), malachite green (MG) and neutral red (NR) were 1892.07 mg·g−1, 786.96 mg·g−1 and 1169.23 mg·g−1, respectively. The adsorption capacity of aerogel toward cationic dyes significantly decreased with an increment of ionic strength. Meanwhile, the thermodynamic study indicated that the adsorption of cationic dyes onto the PIA-g-PA aerogel was spontaneous as an endothermic process. Additionally, the removal efficiency of as-prepared PIA-g-PA aerogel was still above 90.00% even after 10 cycles. Hence, the PIA-g-PA aerogel can be regarded as an eco-friendly adsorbent for the potential remediation of dye pollution in industrial effluents.

Aramid nanofibers/Bacterial cellulose nanocomposite aerogels for high-efficient cationic dye removal

Aramid nanofibers/Bacterial cellulose (ANFs/BC) nanocomposite aerogels have been successfully synthesized via a facile process. Benefiting from the hydrophilicity and negative charge on the surface, the aerogels could selectively adsorb cationic dye in effluent. Compared with slight adsorption of anionic dye methyl orange (MO), the aerogels exhibited high adsorption efficiency for cationic dye methylene blue (MB). The effect of aerogels synthesized by different mass ratios of BC and ANFs on the adsorption efficiency of MB were studied. The dyes removal efficiency (R%) towards MB was 98.8%, which was obviously higher than that of pristine BC aerogels (27.9%). The adsorption kinetic parameters suggested that it fitted the pseudo-second-order model (R2 > 0.99) well and the adsorption process followed the Langmuir model. Besides, the effect of diverse experimental conditions such as adsorption time and initial dyes concentration on the adsorption performance of aerogels was also investigated, the adsorption capacity of aerogels could reach 54.27 mg/g. Consequently, the excellent selective adsorption of ANFs/BC nanocomposite aerogels may exhibit a promising application in effluent treatment.

Investigation of various aerogels as adsorbents for methane storage

Excess CH4 adsorption isotherms on silica aerogel (SA), two resorcinol-formaldehyde aerogels (RFAs) and carbon aerogel (CA) were measured in the temperature range of 298–318K and pressures up to 12MPa. Absolute adsorption isotherms were calculated from experimental excess adsorption isotherms using pore volume of each adsorbent. RFA-17 had maximum absolute CH4 uptake of 22mmol/g at 298K and 10MPa. Adsorption isotherms for all aerogels were well represented with the Freundlich model in the pressure range of the experiments. Excess CH4 uptake was significantly affected by the micropore surface area in aerogels. The isosteric heat of adsorption for each aerogel was found to be dependent on the surface coverage. Among all aerogels, RFA-10 had the highest heat of CH4 adsorption. Adsorption capacities of aerogels were comparable with other classes of adsorbents, which calls for further investigations for development of aerogels as materials for methane storage.

Surface Modification and Properties of SiO<sub>2</sub> Nano Porous Aerogels

Surface modification is a process in which Si-CH3 groups of trimethylchlorosilane (TMCS) replace -OH groups on the inner surface of SiO2 aerogels, so the surface property of aerogels has shown hydrophobic performance which could be changed back to hydrophilic by 450 heat treatment. This aerogels with surface property controlled are prepared via sol-gel process with polyethoxydisiloxanes (E-40) used as precursor, and have typical porous structures dried at ambient pressure: high porosity (above 90 %), super specific surface area (about 1000 m2/g), low bulk density (down to 3.03 kg/m3) and average pore size is about 20 nm. This paper presents adsorption mechanisms in aerogels and illustrates that the adsorption capacity of aerogels is three or four times as much as that of activated carbon fiber (ACF) and granule of activated carbon (GAC). So SiO2 aerogels are potentially important to be used as absorbents being quite efficient to adsorb toxic substances.

Studies on the adsorption of reactive brilliant red X-3B dye on organic and carbon aerogels

Organic aerogels (AGs) and carbon aerogels (CAs) as adsorbents were successfully fabricated by a sol–gel polymerization method. The BET specific surface area and pore size distribution of the samples were analyzed by N 2 adsorption measurements. The adsorption efficiency of prepared samples towards reactive brilliant red X-3B dye (RBRX) was investigated. The adsorption of dye was found to follow the Langmuir and Freundlich models. The thermodynamic parameters, such as the change of free energy, enthalpy and entropy were calculated from equilibrium constants. Kinetic studies indicated that the adsorption of CA followed pseudo first and second order kinetic model, but the adsorption of AG only followed pseudo first order kinetic model. Batch adsorption studies were conducted to evaluate the effects of main preparation and adsorption conditions such as R/C (molar ratio of resorcinol (R) to surfactant (CTAB)) of adsorbent, pH, adsorbent dose and adsorbent particle size on the adsorption of RBRX on AG and CA. The results showed that the adsorption capacity of dye increased with the decrease in dose and particle size of the adsorbent. Maximum adsorption of AGs and CAs was observed at R/C = 200. The adsorption capacity of AG and CA would increase largely when pH < 4 or pH > 12.