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This work presents the results from experiments and modeling of tetrahydrofuran single crystal hydrate growth. The purpose was to study growth kinetics, independent of mass transfer and heat transfer. We used a single crystal apparatus, at stoichiometric concentrations of tetrahydrofuran and water, varying the fluid shear to decrease the boundary layer at the crystal surface. We found that with extreme precautions to totally eliminate mass transfer and to minimize heat transfer via high shear, it is very difficult to obtain reliable kinetic constants for the single hydrate crystal growth system. We eliminated mass transfer, but were only able to reduce the heat transfer resistance to a value of about 10% of the total resistance (i.e., 90% kinetic resistance) at the lowest value of subcooling. We found that growth rate increased with the driving force (i.e., subcooling) and established that the growth process occurred by a step mechanism. We only measured the fluid phases in order to obtain hydrate phase kinetics. The results of this work suggest that assessment of heat transfer, previously ignored in crystal growth kinetic studies is vital for accurate hydrate kinetics.

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In this paper, we investigate the potential of ultrasonic energy in assisting the crystallization of dextrose monohydrate, which is primarily manufactured via slow cool batch, lasting 48 h (0.5°C/h), seeded crystallization; this cooling curve is designed to optimize the crystal growth and give rise to relatively large dextrose crystals. This study was interested in the impact of ultrasound on the nucleation, crystal breakage/size distribution, and rate of growth of the dextrose, while producing a product of the desired crystal size distribution. Experimental results show that ultrasonic energy can be used to induce nucleation and increase the overall mass rate of crystal growth while producing product with the desired crystal size distribution.

The title compound {systematic name: [2-(1-hydroxycyclohexyl)-2-(4-hydroxyphenyl)ethyl]dimethylammonium 3-carboxypropanoate monohydrate}, C(16)H(26)NO(2)(+) x C(4)H(5)O(4)(-) x H(2)O, is a succinate salt of O-desmethylvenlafaxine (desvenlafaxine). The present structure is one of four reported polymorphs of this salt, which is a new antidepressant drug. The carboxyl group of the succinate anion adopts a rare anti conformation and is engaged in a very short O-H...O(-) hydrogen-bond contact. Both cations and anions are involved separately in the formation of distinct O-H...O hydrogen-bonded networks. Desvenlafaxine cations and water molecules self-assemble to generate a honeycomb layer, while the succinate anions form a linear tape structure. These hydrogen-bonded networks are interlinked via N-H...O and O-H...O hydrogen bonds. The hydrogen-bonding network is so strong that desolvation and melting occur together at approximately 402 K. Thus, the crystal structure may be used to understand the thermal stability and solubility of the compound at the molecular level.