Adsorption Isotherm Modelling of Water on Nano-Tailored Mesoporous Silica Based on Distribution Function

Abstract

A new model of adsorption isotherms Type IV and V is proposed as a basis for theoretical calculations and modelling of adsorption systems such as adsorption heat storage and heat pumps. As the current models have decent yet limited applicability, in this work, we present a new combined model with universal use for micro-mesoporous silica/water adsorption systems. Experimental measurement of adsorption isotherm of water onto seven different samples of micro and mesoporous silica and aluminium-silica were used to fit new adsorption models based on a combination of classical theories and a distribution function related to the pore-size distribution of the selected materials. The fitting was conducted through a repeated non-linear regression using Trust Region Reflective algorithm with weighting factors to compensate for the scalability of the adsorption amount at low relative pressure with optimization of the absolute average deviation fitting parameter. The results display a significant improvement for most of the samples and fitting indicators compared to more common models from the literature with average absolute deviation as low as AAD = 0.0025 g g−1 for material with maximum uptake of q = 0.38 g g−1. The newly suggested model, which is based on a combination of BET theory and adjusted normal distribution function, proved to bring a higher degree of precision and universality for mesoporous silica materials with different levels of hydrophilicity.

Cefixime-Containing Silica Nanoseeds Coated by a Hybrid PVA-Gold Network with a Cys–Arg Dipeptide Conjugation: Enhanced Antimicrobial and Drug Release Properties

“…70 As presented in Figure 3a, the BET specific surface area, pore volume, and average pore width for the neat MSNPs (red-line curves) are 72.32 m 2 /g, 0.15 cm 3 /g, and 83.67 Å, indicating type IV isotherm of the mesoporous materials with very narrow capillary pores. 71 As expected, these values have been reduced to 54.72 m 2 /g, 0.08 cm 3 /g, and 58.48 Å after incorporation of CFM into the pores (blue-line curves). Also, after coating the surface of the CFM@SiO 2 nanoparticles with the PVA, the BET surface area has been significantly reduced to 7.22 m 2 /g and a broad pore size distribution has appeared, as shown in Figure 3b (black-line curve).…”

Synthesis of molecularly imprinted polymer with a methacrylate derivative monomer for the isolation of ethyl p-methoxycinnamate as an active compound from Kaempferia galanga L. extracts

“…This could be because the adsorbate may have a strong affinity for the adsorbent, which makes it difficult for the adsorbate to desorb, so desorption does not occur at low pressure. 62 …”

Efficient Photodegradation of Eriochrome Black-T by a Trimetallic Magnetic Self-Synthesized Nanophotocatalyst Based on Zn/Au/Fe-Embedded Poly(vinyl alcohol)

“…The BET specific surface area and pore volume of the photocatalyst before photodegradation are 119.2564 m 2 /g and 0.4161 cm 3 /g (the blue curves), respectively. 61 Expectedly, after the EBT photocatalytic degradation, the BET specific surface area and pore volume are decreased to 50.7385 m 2 /g and 0.2361 cm 3 /g, respectively, representing type IV isotherm of the mesoporous materials with very narrow capillary pores (the red curves). The possible justification for this reduction is the penetration of the EBT dye and the degraded substances into the pores of the Fe 3 O 4 @PVA-Au/ZnO magnetic photocatalytic system, leading to the formation of a mesoporous structure.…”