Abstract Verapamil is a chiral drug that is marketed in its racemic form, but because of the pharmacological effects due to molecule’s chirality, one of the enantiomers is more potent, and the other exhibits different activities of therapeutic interest. The preparative separation of the verapamil enantiomers was performed using a continuous Varicol unit operated on a scale of 1 g/day. Amylose tris(3,5-dimethylphenylcarbamate) functioned as the stationary phase, and n-hexane/isopropanol/ethanol mixtures were used as the mobile phase. Diethylamine was used as the additive. The enantiomeric purities were 93.0% for S-(-)-verapamil and 92.0% for R-(+)-verapamil in the raffinate and extract streams, respectively. The unit provided productivities of 0.18 kg of raffinate per day per kg of adsorbent and 0.20 kg of extract per day per kg of adsorbent when using a feed concentration of 12.5 g L-1.

An experimental and theoretical study is presented for the fractionation of L-Tryptophan (Trp) from L-phenylalanine (Phe) and L-tyrosine (Tyr). A Simulated-Moving Bed (SMB) with four-column system was tested, and the results are presented as effluent histories of the raffinate and extract ports. L-phenylalanine and L-tyrosine were recovered as major products in the raffinate, while L-Tryptophan was recovered at the extract. To simulate the L-Tryptophan separation, a general rate model was used to represent the mass transfer phenomena that occur in each individual column of the SMB, for each solute present in the multicomponent system. A hybrid method was used to solve the model. An analytic solution was used for the intra-particle concentration, and was correlated to the liquid bed concentration by Duhamel's theorem. The results from simulation are compared with the experimental data presented in this work.

In this communication, the method proposed by Cremasco et al. (2003) is applied to predict single and low concentration pulse chromatography. In previous work, a general rate model was presented to describe the breakthrough curve, where a hybrid solution was proposed for the linear adsorption. The liquid phase concentration inside the particle was found analytically and related with the bed liquid phase through Duhamel's Theorem, while the bulk-phase equation was solved by a numerical method. In this paper, this method is applied to describe pulse chromatography of solutes that present linear adsorption isotherms. The simulated results of pulse chromatography are compared with experimental ones for aromatic amino acid experiments from literature.

A laboratory-scale simulated moving bed (SMB) was designed and tested for the separation of paclitaxel, a powerful anti-cancer agent known as Taxol@, from impurities of a plant tissue culture (PTC) broth. The innovative strategy of a pseudo-binary model, where mixtures A and B were treated as single solutes A and B, was used in the linear standing wave analysis to fix the SMB operating parameters for a multicomponent and complex system. Linear standing wave design was used to specify the zone flow rates and the switching time for the laboratory-scale SMB unit, with two steps of separation. The SMB consists of four packed columns, where each column is 12.5 cm in length and 1.5 cm in diameter. Two sequential separation steps were used to recover paclitaxel from a small feed batch (less than one liter). Placlitaxel was recovered from the complex plant tissue culture broth in 82% yield and 72% purity.

In this paper, a new resolution method for the dynamic simulation of a simulated moving bed is presented. A general rate model for each solute and each column is presented for the case of a linear isotherm. A hybrid resolution is developed, in which an analytical solution is used for the solid stationary phase, while the mobile fluid phase concentrations are obtained by numerical resolution. It is illustrated, through a numerical study, that the resolution method is robust. The method is validated by comparison with previously published experimental results. It is also shown that these numerical simulations are obtained much faster than those based on the physical separation process, allowing the use of this resolution method for on-line applications and process control.

Piper hispidinervium C.DC (Piperaceae) is popularly known as long pepper. It grows in degraded areas of natural fields in the state of Acre, Brazil. Its leaves are 3 to 4 % essential oil rich in safrole, within the range of 90 to 94 %. In the chemical industry, safrole is an important raw material, mainly due to two of its derivatives: heliotropin, which is widely used as a fragrance and flavoring agent, and piperonyl butoxide (PBO), a vital ingredient of pyrethroid insecticides. Natural pyrethrum in particular would not be an economical insecticide without the synergistic effect of PBO; therefore, its industrial future is linked to the continued availability of PBO. As a fragrance, safrole has many applications in household products such as floor waxes, polishes, soaps, detergents and cleaning agents. In this work, leaves were dried in a fixed-bed dryer using different drying-air temperatures (35, 40, 45, 50, 55 and 60 ºC) and drying times (900, 2700 and 3600 seconds). Essential oil was extracted by cohobation (meaning that the condensed water that comes out of the flask is recycled) from both raw and dried leaves. The essential oil yield and safrole content are susceptible to rapid loss of moisture by Piper hispidinervium C. DC leaves. It was observed that the essential oil yield increased twice after the drying process. However, safrole content decreased about 20 percent when temperature was above 50 ºC and drying times were more than 2700 minutes.

Pastelike materials are encountered in many technological processes in chemical, pharmaceutical, foodstuff and natural product industries. The most important factor in the drying of this type of materials is the nature of the moisture bonding that occurs. Because of the different characteristics of pastes, it is impossible to recommend a universal type of dryer for all of these materials. Some of the dryers available provide only indirect contact with the drying agent (heat) and also maintain constant moisture with a system of rotating paddles. We evaluated the performance of this type by studying the dryer kinetics curves for ground coffee under a variety of operational conditions of moisture load of material, temperature of the heating plate, intensity of the mechanical mixing of the moisture material, and initial moisture. The effects of these parameters (except for moisture) were studied using a 2³ factorial design. According the analyses of the kinetics drying curves, was observed that the increase in the temperature of the plate and rotation as well as the decrease in the load facilitates more effective removal of moisture. In statistical analysis was determined that the load of the material and the heating plate temperature influence the final moisture content of the material and plate temperature modifies the final temperature of the solid. Also, was suggested linear models from the factorial design to describe the process of drying coffee grounds satisfactorily.