The modeling of crystal quality (size, shape, and purity) is discussed. Numerical methods for the model solution are reviewed including collocation and Galerkin's method on finite elements. Measurement technologies for on-line crystal size distribution are presented. The difficulties with laser light scattering methods are discussed in detail. Parameter estimation is reviewed and new methods based on nonlinear optimization are presented. Sample calculations of parameters and their uncertainty from experimental data are included. The research literature covering control of continuous and batch crystallization is reviewed, and sample calculations of optimal cooling profiles for batch crystallizers are presented

Model identification and control of solution crystallization processes: a review

The present invention relates to a process for the production of the fine chemical in a microorganism, a plant cell, a plant, a plant tissue or in one or more parts thereof, preferably in plastids. The invention furthermore relates to nucleic acid molecules, polypeptides, nucleic acid constructs, vectors, antibodies, host cells, plant tissue, propagation material, harvested material, plants, microorganisms as well as agricultural compositions and to their use.

Process for the production of fine chemicals

The shape of a crystalline organic solid has a major impact on its downstream processing and on its end-product quality, issues that are becoming increasingly important in the specialty and fine chemical, as well as the pharmaceutical and life science, industries. Though it is widely known that improved crystal shapes can be achieved by varying the conditions of crystallization (such as solvent type and impurity levels), there is far less understanding of how to effect such a change. Until recently, most methods for predicting crystal shapes were based exclusively on the internal crystal structure, and hence could not account for solvent or impurity effects. New approaches, however, offer the possibility of accurately predicting the effects of solvents. Models for predicting crystal shape are reviewed, as well as their utility for process and product design.

Modeling crystal shapes of organic materials grown from solution

Square-wave voltammetry (SWV) is one of the four major voltammetric techniques provided by modern computer-controlled electroanalytical instruments, such as Autolab and μAutolab (both EcoChemie, Utrecht), BAS 100 A (Bioanalytical Systems), and PAR Model 384 B (Princeton Applied Research) [1]. The other three important techniques are single scan and cyclic staircase, pulse, and differential pulse voltammetry (see Chap. II.2). All four are either directly applied or after a preconcentration to record the stripping process. The application of SWV boomed in the last decade, first because of the widespread use of the instruments mentioned above, second because of a well-developed theory, and finally, and most importantly, because of its high sensitivity to surface-confined electrode reactions. Adsorptive stripping SWV is the best electroanalytical method for the determination of electroactive organic molecules that are adsorbed on the electrode surface [2].

Square-wave voltammetry

Many of the crystals in the pharmaceuticals, photographic, and other industries are multidimensional; that is, their growth is associated with the change of multiple internal coordinates. The main governing equation for such systems is a highly nonlinear multidimensional population balance equation that must be solved for a wide range of length scales. For population balance equations, it is well-known that the standard first-order schemes give diffusive solutions while the commonly used second-order schemes give spurious oscillations. This paper presents a high-resolution simulation algorithm that provides short computation times and high accuracy. The high-resolution algorithm is compared to the upwind difference and Lax-Wendroff methods through simulations of potassium dihydrogen phosphate (KDP, KH 2 PO 4 ) crystal nucleation and growth. No spurious oscillations or numerical diffusion occurred, in contrast to the upwind method and Lax-Wendroff methods. The numerical stability of the algorithm is assessed using the Courant-Friedrichs-Lewy condition.

High-Resolution Simulation of Multidimensional Crystal Growth

Improved separations of xylose, mannose, galactose, arabinose, glucose, xylitol, arabitol, sorbitol, galactitol, or mannitol (and other monosaccharides and sugar alcohols) from other sugars and sugar alcohols may be achieved by chromatography over hydroxyl-form anion exchange surfaces prepared from anion exchange resins at relatively low hydroxyl concentrations. When a strong base anion exchange resin, such as a chloride-form strong base anion exchange resin, is conditioned with a low concentration of hydroxyl (for example, an NaOH solution with a concentration between 0.1 and 1000 nM, most preferably between 1 and 10 mM), the conditioned resin separates a number of sugars and sugar alcohols from one another, while still allowing ready desorption from the resin.

Process for the separation of sugars

The theoretical shape of sucrose crystals from energy calculations

When a strong base anion exchange resin, such as a chloride-form strong base anion exchange resin, is conditioned with a low concentration of hydroxyl (for example, an NaOH solution with a concentration between 1 and 10 mM), the conditioned resin separates in, sit, Is from sugars and sugar alcohols, while still allowing ready desorption of the sugars from the resin. The feedstock is first passed over a column containing this conditioned resin, followed by a mobile phase solvent, preferably water. The inositols have a lower affinity for the treated resin than do the sugars and sugar alcohols in the feedstock, and therefore pass through the column more quickly. The process may economically be performed on industrial-scale inositol separations, particularly when used in a preferred simulated moving bed chromatographic system.

Separation of inositols from sugars and sugar alcohols

Nanofiltration is used to decolorize sugar juice or syrup. The resulting permeate may be used directly to crystallize white sugar without an intermediate step of producing a raw sugar; even though the color of the permeate is substantially higher than the highest color that is acceptable in a conventionally decolorized syrup used to crystallize white sugar. Significant cost savings are thus achieved in producing white sugar.

Method for producing white sugar

This invention relates to a process for the purification of crude terephtic acid. The process includes heating the crude acid on a first plate and locating a second plate adjacent the first plate whereby vapors emanating from the crude acid form a sublimate on the second plate. The principal impurity removed is 4-carboxybenzaldehyde. The crude acid produced is applied to the first plate as a layer having a thickness of about 2 to about 5 mms thick and heated to a temperature of from about 180° to about 220° C. The upper plate is not heated except by the convective heat transfer and the heat of sublimation provided by the vapor moving from the crude acid layer to the second plate.

Michael Saska

Papers

Process for the separation of sugars

The theoretical shape of sucrose crystals from energy calculations

Separation of inositols from sugars and sugar alcohols

Method for producing white sugar

Process for reducing the 4-carboxybenzaldehyde content of a crude terephthalic acid product