title: Direct Coexistence Methods to Determine the Solubility of Salts in Water from Numerical Simulations. Test Case NaCl.
abstract: The solubility of NaCl, an equilibrium between a saturated solution of ions and a solid with a crystalline structure, was obtained from molecular dynamics simulations using the SPC/E and TIP4P-Ew water models. Four initial setups on supersaturated systems were tested on sodium chloride (NaCl) solutions to determine the equilibrium conditions and computational performance: (1) an ionic solution confined between two crystal plates of periodic NaCl, (2) a solution with all the ions initially distributed randomly, (3) a nanocrystal immersed in pure water, and (4) a nanocrystal immersed in an ionic solution. In some cases, the equilibration of the system can take several microseconds. The results from this work showed that the solubility of NaCl was the same, within simulation error, for the four setups, and in agreement with previously reported values from simulations with the setup (1). The system of a nanocrystal immersed in supersaturated solution was found to equilibrate faster than others. In agreement with laser-Doppler droplet measurements, at equilibrium with the solution the crystals in all the setups had a slight positive charge.
authors.affiliation: †Escuela Superior de Cómputo del I.P.N, Av. Juan de Dios Bátiz s/n Miguel Othón de Mendizabal, 07738 México, D.F., México.
authors.forename: Héctor M
authors.initials: HM
authors.lastname: Manzanilla-Granados
authors.affiliation: ‡Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apdo. Postal 48-3, Cuernavaca, Morelos C.P. 62251, México.
authors.forename: Humberto
authors.initials: H
authors.lastname: Saint-Martín
authors.affiliation: ¶Instituto de Física, Universidade Federal do Río Grande do Sul, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS Brazil.
authors.forename: Raúl
authors.initials: R
authors.lastname: Fuentes-Azcatl
authors.affiliation: §Departamento de Química, Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, C.P. 09340 México, D.F., México.
authors.forename: José
authors.initials: J
authors.lastname: Alejandre