A New Approach in Predicting Gas Adsorption Isotherms and Isosteric Heats Based on Two-Dimensional Equations of State

Dendrimers with Tetraphenylmethane Moiety as a Central Core: Synthesis, a Pore Study and the Adsorption of Volatile Organic Compounds

Reasonable yields of two dendrimers with central tetraphenylmethane and peripheral 3,5-di-(tert-butanoylamino)benzoylpiperazine moieties are prepared. These dendrimers have a void space in the solid state so they adsorb guest molecules. Their BET values vary, depending on the H-bond interaction between the peripheral moiety and the gas molecules, and the dendritic framework that fabricates the void space is flexible. In the presence of polar gas molecules such as CO₂, the BET increases significantly and is about 4–8 times the BET under N₂. One dendrimer adsorbs cyanobenzene to a level of 436 mg/g, which, to the authors’ best knowledge, is almost equivalent to the highest reported value in the literature.

Evaluation of the Adsorptive Process on Adsorbent Surfaces as a Function of Pressure in an Isosteric System Compared with Adsorption Isotherm

The developing significance of adsorption has brought about a steadily expanding quantity of logical and innovative writing on different adsorbents. This paper intends to propose experimental and computational methods for measuring the strength of adsorbate–solid interactions. It primarily focuses on the use of graphs to measure the effectiveness of an adsorbate’s bonds with the solid adsorbent by determining the isosteric heat. The Clausius–Clapeyron model equation is used to determine the isosteric enthalpy of adsorption from two adsorption isotherms at various but close temperatures, with ΔT of 10 °C. A full computational explanation of the Clausius–Clapeyron model equation for determining ΔHads is provided using experimental data. Logarithmic plots of uptakes vs. p in the low-pressure zone for the Freundlich–Langmuir graph are used to assess and confirm the quality of the crucial underlying isotherms. The isosteric heat was found to be between 13.5 kJ/mol and 16 kJ/mol.

Adsorbing Volatile Organic Chemicals by Soluble Triazine-Based Dendrimers under Ambient Conditions with the Adsorption Capacity of Pyridine up to 946.2 mg/g

Two triazine-based dendrimers with peripheral 1,3,5-triamidobenzene (1-3-5-TAB) functionality were prepared, and their void spaces in the bulk solid were investigated. We examined dendrimers of three core lengths and determined the one with the longest core exhibits the largest void space because the peripheral amides were not imbedded in the internal space of each dendritic molecule. The new dendrimers as solids were observed to adsorb volatile organic chemicals efficiently. Importantly, because the dendrimers are soluble in organic solvents, the adsorbed VOCs can be quantified by ¹H-NMR spectroscopy by choosing a chemical shift (δ) of dendrimers as the internal standard to exclude interfering impurity signals, a much simpler and more efficient protocol than the traditional GC technique for the VOC quantification. One dendrimer was found to adsorb 24 equivalents of pyridine, so its adsorption capacity is equivalent to 946.2 mg/g. This is a more than 2-fold increase than the reported values by other porous materials.