Reconciliation of Kinetic Data for Organic Crystal Growth in Supercritical-CO_2: Exploiting a Molecular Collision Theory Viewpoint, with Implications for Precipitator Process Design

摘要

Exploiting a molecular “collision-theory” viewpoint, we reformulate and correct for systematic effects of fluid-phase solute diffusion, reported growth-rate data for {001} naphthalene single crystal surfaces under supercritical CO_2-conditions at low supersaturations, S. By considering dimensionless incorporation probabilities, ε(S, T, ...; {hkl}) for this prototypical organic crystal, we initiate the process of quantifying the environment-dependence of ε as a rational route to crystal growth rate predictions at molecular volume fractions, φ, ranging all the way from ideal vapors (φ ? 1) to liquidlike densities (φ ? 0.64). Our rational “ansatz” for predicting growth species collision fluxes enables a two-stage data-reduction process. First we infer “apparent” incorporation probabilities, εapp, ignoring fluid-phase solute diffusion effects. Second, we recover their intrinsic counterparts, using εapp and invoking rational transport estimates for the prevailing crystal size/flow conditions. Treating available data near 318 K at 77?91 bar (Tai, C. Y.; Cheng, C.-S. AIChE J. 1995, 41, 2227?2236) and 150?200 bar (Uchida et al. Cryst. Growth Des. 2004, 4, 937?942), we conclude that ε decreases significantly with (CO_(2-)) pressurewith important mechanistic and anti-solvent precipitation (ASP) process modeling implications.