Screening of carbonaceous nanoporous materials for capture of nerve agents

Abstract

A strategy for combined experimental and computational screening of candidate carbonaceous materials for capturing highly volatile nerve agents at ambient temperature using physisorption. Based on theoretical calculations of Henry constants and zero-coverage adsorption enthalpies for sarin and DMMP (its common stimulant) adsorbed in model slit-shaped carbon pores at 298 K, we found the following. Slit-shaped carbon pores with pore width ~0.5 nm are optimal for agent adsorption due to strong confinement of adsorbed molecules. Agent adsorption enthalpy at zero coverage computed for optimal pore width is very high and reaches ~83 kJ mol(-1). Widening of pore width above ~1 nm results in a significant decrease of the Henry constant and zero-coverage adsorption enthalpy (~44 kJ mol(-1)). Polydispersity of studied candidate carbonaceous materials strongly affects adsorption capacity for DMMP under the operating conditions. The optimal carbonaceous adsorbent, pitch-based P7 activated carbon fiber, adsorbed ~100 μg g(-1) DMMP at 0.03 μg m(-3). Commercial Norit activated carbon adsorbed only ~20 μg g(-1) DMMP at 0.03 μg m(-3). Surprisingly, a small shift of the pore size distribution towards wider micropores has a great impact on agent adsorption. Because the adsorption enthalpies computed at zero coverage weakly dependent on pore size, the heat released during agent adsorption is similar for all studied candidate adsorbents (i.e.~55-60 kJ mol(-1)).

Morphologically disordered pore model for characterization of micro-mesoporous carbons

“…MDSP revels a genuine bimodal structure with micropores < ~2.0 nm and narrow mesopores ~2.0-6.0 nm. We note that, due to the morphological disorder of LMA10 pore walls, the PSDs computed from MPSD model are free from artificial sharp minima such as gaps around ~1 nm, as has been previously reported from NLDFT calculations [11,18,84].…”

“…This set up allowed us to get better estimations of GCMC averages because we simulated nitogen adsorption isotherm on two identical carbon surfaces. The size of the simulation box in direction parallel to pore walls was previously verified in order to eliminate finite size effects [11,68]. Figure 1).…”

“…One of the experimental justifications for using idealized slit-shaped pores is that the pore walls in activated carbons appear to be graphite basal planes, which present nearly flat surfaces for adsorption [5,6]. Non-local density functional theory (NLDFT) and the grand canonical Monte Carlo simulation (GCMC) have implemented the independent slit-shaped pore model with smooth graphitic walls for pore size analysis of complex micro-mesoporous carbons [7][8][9][10][11][12][13]. The use of NLDFT kernels of theoretical nitrogen isotherms (77 K) generated in crystalline graphitic slit-shaped pores has greatly improved the realism of pore size analysis in the micropore region (pore size < 2 nm [14]) compared to the traditional phenomenological methods.…”

Molecular simulation aided nanoporous carbon design for highly efficient low-concentrated formaldehyde capture

“…To compare theoretical results for pure and oxidized carbons, we used pore width defined above consistently throughout the paper. We computed the Henry constant from the statistical mechanical expression using in-house Metropolis-Ulam Monte Carlo algorithm with OPLS-AA force field (section 2.1 and 2.4 in the supporting information) [36,37]. For selected pore widths, e.g.…”

Detoxification of Chemical Warfare Agents Using a Zr6‐Based Metal–Organic Framework/Polymer Mixture

“…[1] To xic organophosphates bind irreversibly to the enzyme acetylcholinesterase (AChE),p reventing the breakdown of acetylcholine, which leads to sustainedm uscle contraction, and eventually oxygend eprivation and death. [1, 2] Though some organophosphatesc an be decomposedb yh ydrolysis in water,r eaction rates in the absence of catalystsa re typicallyt oo slow to be effective.T hereh ave been many studies focusingo nt he detoxificationo rr emoval of simulants and nerve agents using catalysts such as metalo xides (TiO 2 , Zr(OH) 4 ,a nd Al 2 O 3 ), [3] activated carbon, [4] mesoporous silica, [5] zeolites, [6] and surfactants/metallosurfactants. [7] However,m ore highlyp otent catalytically active materials are needed.To wards the goal of nerve-agentd etoxification, some researchg roups includingours have studied various kinds of catalysts includings upramolecular assemblies, [8] porous organic polymers (POPs), [9] and metal-organicf rameworks (MOFs).…”