3-Aminopropyltriethoxysilane-aided cross-linked chitosan membranes for gas separation: grand canonical Monte Carlo and molecular dynamics simulations

A theoretical probe into the separation of CO2/CH4/N2 mixtures with polysulfone/polydimethylsiloxane-nano zinc oxide MMM

In the current investigation, molecular dynamics (MD) and Grand Canonical Monte Carlo (GCMC) simulation as remarkable and competent approaches have been employed for understanding structural and transport properties of MMMs in the realm of gas separation. The two commonly used polymers i.e. polysulfone (Psf) and polydimethylsiloxane (PDMS) as well as zinc oxide (ZnO) nanoparticle (NP) were used to carefully examine the transport properties of three light gasses (CO₂, N₂ and CH₄) through simple Psf, Psf/PDMS composite loaded by different amounts of ZnO NP. Also, the fractional free volume (FFV), X-ray diffraction (XRD), glass transition temperature (T_g), and Equilibrium density were calculated to scrutinize the structural characterizations of the membranes. Moreover, the effect of feed pressure (4-16 bar) on gas separation performance of simulated MMMs was investigated. Results obtained in different experiments showed a clear improvement in the performance of simulated membranes by adding PDMS to PSf matrix. The selectivity of studied MMMs was in the range from 50.91 to 63.05 at pressures varying from 4 to 16 bar for the CO₂/N₂ gas pair, whereas the corresponding value for CO₂/CH₄ system was found to be in the range 27.27-46.24. For 6 wt% ZnO in 80%PSf + 20%PDMS membrane, high permeabilities of 78.02, 2.86 and 1.33 barrers were observed for CO₂, CH₄ and N₂ gases, respectively. The 90%PSf + 10%PDMS membrane with 2% ZnO had a highest CO₂/N₂ selectivity value of 63.05 and its CO₂ permeability at 8 bar was 57 barrer.

The conformational change of Plukenetia conophora oil derivatives and their acidic resistance, intra-fragment interactions, stability in different solvent media

The synthesis of derivatives of bio-based lubricants from vegetable oil as an alternative to petroleum oil is significant due to the oil crisis, global warming, higher demand and serious environmental threat. In this study, the molecular properties of three derivatives of oil derived from Plukenetia conophora seeds, namely Plukenetia conophora oil (PK), rpoxidised Plukenetia conophora oil (EP) and poly(hydroxybutanethiol-ether) derivative of Plukenetia conophora oil (BP), were examined in acidic media and crystal form. The derivative BP has the highest resistance to acidic attack as evident from their poor interaction with acidic H₃O⁺ from both HCl and HNO₃. BP also has the best tendency of forming a crystal as evident from the lowest atomic diffusion in crystal model (L12). However, the result of the molecular electrostatic potential (MESP) analysis shows that BP has more electron-deficient surface compare to EP derivatives. The derivative BP is also found to have the lowest potential energy and higher root means square deviation (RMSD) of its atoms. Density clustering analysis further confirms that BP did not retain its most stable conformation for a longer period of simulation compared to PK and EP. The most visited conformation from the hierarchical and density clustering also corresponds to the minimum potential energy on the potential energy surface.Graphical abstract.