A Statistical Approach to Determine Optimal Models for IUPAC-Classified Adsorption Isotherms

Abstract

Adsorption heat transformation (AHT) systems can play a major role in protecting our environment by decreasing the usage of fossil fuels and utilizing natural and alternative working fluids. The adsorption isotherm is the most important feature in characterizing an AHT system. There are eight types of International Union of Pure and Applied Chemistry (IUPAC) classified adsorption isotherms for different “adsorbent-adsorbate” pairs with numerous empirical or semi-empirical mathematical models to fit them. Researchers face difficulties in choosing the best isotherm model to describe their experimental findings as there are several models for a single type of adsorption isotherm. This study presents the optimal models for all eight types of isotherms employing several useful statistical approaches such as average error; confidence interval (CI), information criterion (ICs), and proportion tests using bootstrap sampling. Isotherm data of 13 working pairs (which include all eight types of IUPAC isotherms) for AHT applications are extracted from literature and fitted with appropriate models using two error functions. It was found that modified Brunauer–Emmet–Teller (BET) for Type-I(a) and Type-II; Tóth for Type-I(b); GAB for Type-III; Ng et al. model for Type-IV(a) and Type-IV(b); Sun and Chakraborty model for Type-V; and Yahia et al. model for Type-VI are the most appropriate as they ensure less information loss compared to other models. Moreover; the findings are affirmed using selection probability; overall; and pairwise proportion tests. The present findings are important in the rigorous analysis of isotherm data.

Adsorption Characteristics of Zeolite A Synthesized from Wassa Kaolin for Thermal Energy Storage

“…The zeolite crystal structure, geometry and presence of acceptor centers contribute to the adsorption volume (Akimkhan, 2012). The maximum adsorbed amount of adsorbate at a specific pressure and temperature is defined as the equilibrium uptake (Rahman, Muttakin, Pal, Shafiullah, & Saha, 2019). This can be represented with an isotherm model to show the varied uptakes with respect to pressure.…”

“…Although no best-fit model exists for Zeolite A -water pair adsorption, it is evident that the adsorption was favourable. In the application of the Langmuir model, it is assumed that the adsorbent is homogenous and that each adsorption site is occupied by only one atom (Rahman et al, 2019).…”

Optimization of Strontium Removal Process From Contaminated Water Using Zeolite Nanocomposites

“…In order to explain the attaching of different species to homogeneous substrates, the Hill equation (Rahman et al 2019) is used. It can be presented as follows-…”

Simulation-based Optimum Models for Type-I(a) and Type-I(b) IUPAC Classified Adsorption Isotherms

“…In our previous research, the optimal models in IUPAC-classified isotherms were determined using statistical method [15]. The isotherm model's parameters were determined using non-linear generalized reduced gradient (GRG) method.…”

“…And in this situation, attention should be given to the sensitivity or variation of the parameters. On the other hand, the previous research [15] considered information criteria to find optimum model. Sometimes information-based criterion selects the model that have more parameters compare to other models.…”