Paolo Cosoli

Grand Canonical Monte-Carlo simulations for VOCs adsorption in non-polar zeolites

Removal of Volatile Organic Compounds (VOCs) by sorption in non-polar zeolite materials (AFR, BOG, LTL) has been tested by Grand Canonical Monte-Carlo (GCMC) molecular simulation techniques. Computational details and simulation procedure were validated by comparison with experimental data reported in literature. Results showed promising adsorption properties in the low pressure range. The adsorption isotherms for each single component could be obtained nicely by Langmuir equation. Molecular simulation techniques have proven to be a powerful tool to predict properties and suggest solutions, even in the relatively unexplored environmental field.

Molecular simulation of atrazine adhesion and diffusion in a saturated sand model.

This paper presents an extensive study about atrazine behavior in saturated sands by the aid of molecular simulation techniques. Systems have been described in a simplified way to predict adhesion and diffusion phenomena, and to give useful insights at the atomistic level. Diffusion coefficients, binding energies, and concentration profiles have been determined as a function of interlayer distances and atrazine concentration. Combined Monte Carlo, Molecular Mechanics, and Molecular Dynamics techniques have been used. In silico results have been compared with available experimental data for validation, and with similar in silico experiments, finding a good agreement. Results confirm a moderate atrazine adhesion onto silica framework and a more favorable tendency to bind with water. Atrazine diffusion has been found to be influenced by concentration and interlayer distance. Encouraging results show how these techniques can be generalized and made applicable for soil contamination modelling at the atomistic level in a more extensive way.

GCMC simulations in zeolite MFI and activated carbon for benzene removal from exhaust gaseous streams

A set of grand canonical Monte Carlo molecular simulations has been performed over zeolite MFI (Zeolite Socony Mobil‐five) and disordered, activated carbon structures, to determine adsorption isotherms and thermodynamic characteristics of a gaseous mixture adsorbed into porous structures, activated carbon, all-silica MFI and hydrophilic FAU (Faujasite)–NaY zeolites. Simulations have been carried out over a multi-component mixture, in order to mimic a more realistic gaseous emission, when benzene has to be removed. Validation of the model has been obtained by comparison with available experimental data. Different conditions, as temperature and total pressure of the stream have been taken into account. Results give a ranking for the most appropriate process conditions, and for the best materials to be employed for the separation process. Data fitting with the Sips thermodynamic model has also been provided for benzene isotherms. Our procedure is simple and may be adapted to different temperature and pressure conditions, adsorbate or adsorbent characteristics, and gas composition.

Release of Proteins from Nanochannel Delivery Systems: A Coupled Many-Scale Simulation - Experimental Investigation

Transport and surface interactions of proteins in nanopore membranes play a key role in many processes of biomedical importance. Although the use of porous materials provides a large surface-to-volume ratio, the efficiency of the operations is often determined by transport behavior, and this is complicated by the fact that transport paths (i.e., the pores) are frequently of molecular dimensions. Under these conditions, wall effects become significant, with the mobility of molecules being affected by hydrodynamic interactions between protein molecules and the wall. Modeling of transport in pores is normally carried out at the continuum level, making use of such parameters as hindrance coefficients; these in turn are typically estimated using continuum methods applied at the level of individual diffusing particles. In this work we coupled experimental evidences to manyscale molecular simulations for the analysis of hen egg-white lysozyme adsorption/diffusion through a microfabricated silicon membrane, having pores of nanometric size in only one dimension. Our joint efforts allowed us a) to elucidate the specific mechanisms of interaction between the biopolymer and the silicon surface, and b) to derive molecular energetic and structural parameters to be employed in the formulation of a mathematical model of diffusion, thus filling the gap between the nano- and the macroscale.

Many-Scale Simulation of ABS/PC Blends for the Automotive Industry

Industrial scraps cannot be reused in an advantageous way, mainly because of their degradation. When possible, rejects are added to the virgin material for new molding, although the amount of recycled block copolymer cannot exceed 15% of moldable material to obtain good final performances. The remaining amount of scraps then follows three different routes: i) employment in very poor applications, ii) land filling, and iii) thermal treatment. For this reason, post industrial rejects constitute a major problem both from the standpoint of the European legislation and policy, and from the economic side where enterprises are concerned. In this work we have applied a multiscale simulation approach to study the nanostructured equilibrium morphology of blends consisting of mainly recycled block copolymers of special interest in the automotive industry. The main goal was the definition of the possible causes leading to incompatibility due to non virgin materials. In particular, starting from atomistic-based simulations we derived a procedure to 1) describe in appropriate fashion the polymer chains in terms of the relevant Gaussian models, and 2) determine the relevant Flory-Huggins interaction parameters. Finally, we coupled mesoscale model with finite elements codes to obtain a quantified structure-property relationship for mechanical modulus and coefficient of thermal expansion.