A class of one-way isothermal Mass transfer processes is investigated in this paper. Based on the definition of Mass entransy, the entransy dissipation function, which reflects the irreversibility of the Mass transfer ability loss, is derived. The optimality condition for the minimum entransy dissipation of the Mass transfer process with a generalized Mass transfer law is obtained by applying an optimal control theory. Special cases for the linear [g µ D(m)] and the diffusive [g µ D(c)] Mass transfer laws are obtained based on the general optimization results. The obtained results are also compared with strategies of minimum entropy generation, constant concentration ratio and constant concentration difference operations. The results obtained herein can provide some theoretical guidelines for optimal design and operation of practical Mass transfer processes.

In this paper, recovery of penicillin G from mycel-containing fermentation broth through physical extraction is investigated. The values of degree of extraction are evaluated as a function of media pH, partition coefficient between aqueous and organic phases for undissociated acid and the pKa of penicillin. The pH variations were measured during extraction operation and the optimum pH value for penicillin G recovery considering its decomposition was obtained. The Mass transfer analysis of the extraction system was carried out using two-resistance Mass transfer theory. The overall as well as aqueous and organic phase Mass transfer coefficients were determined. The investigated Mass transfer resistances for both phases are in the same order of magnitude, demonstrating that the Mass transfer resistances for both phases have to be considered in equipment design and operation of penicillin G extraction systems.

Leather manufacturing involves a crucial energy-intensive drying stage in the finishing process to remove its residual moisture. Determining drying characteristics of leather is vitally important so as to optimize the drying stage. This paper describes an analytical way for determination of the drying characteristics of leather. The model presented, is based on fundamental heat adn Mass transfer equations. Variations in temperature and moisture content distribution is solved numerically using the finite difference method. The effects of operation parameters are examined using the model. The results of the parametric study provide a better understanding of the drying mechanisms and may lead to a series of recommendations for leather drying optimization. It opens the possibility for further investigations on description of relationships between model parameters and drying conditions.