Reactive distillation (RD) has already demonstrated its potential to significantly increase reactant conversion and the purity of the target product. Our work focuses on the application of RD to reaction systems that feature more than one main reaction. In such multiple-reaction systems, the application of RD would enhance not only the reactant conversion but also the selectivity of the target product. The potential of RD to improve the product selectivity of multiple-reaction systems has not yet been fully exploited because of a shortage of available comprehensive experimental and theoretical studies. In the present article, we want to theoretically identify the full potential of RD technology in multiple-reaction systems by performing a detailed optimisation study. An evolutionary algorithm was applied and the obtained results were compared with those of a conventional stirred tank reactor to quantify the potential of RD to improve the target product selectivity of multiple-reaction systems. The consecutive transesterification of dimethyl carbonate with ethanol to form ethyl methyl carbonate and diethyl carbonate was used as a case study.
Foam fractionation process for concentration of laccases from two Basidiomycete strains under different process conditions was investigated. Culture supernatants of Cerrena unicolor and Pleurotus sapidus containing active laccase were used with and without surfactant additives. Two surfactants: cationic cetrimonium bromide (CTAB) and non-ionic Polysorbate 80 were applied in the range from 0.2 mM to 1.5 mM. The pH levels ranging from 3 to 10 were examined with particular attention to pH=4, which is close to the pI of the enzymes. Results show that the source of the enzyme is significant in terms of partitioning efficiency in a foam fractionation process. Laccase from Cerrena unicolor showed the best activity partitioning coefficients between foamate and retentate of almost 200 with yields reaching 50% for pH 7.5 and concentration of CTAB cCTAB = 0.5 mM, whereas laccase from Pleurotus sapidus showed partitioning coefficients of up to 8 with 25% yield for pH 4 and cCTAB = 0.5 mM.
Culture supernatant containing laccase produced by Cerrena unicolor strain was used to examine laccase partitioning between phases in an aqueous two-phase system. The investigated system consisted of polyethylene glycol 3000 and sodium phosphate buffer adjusted to pH = 7. Influence of several parameters on partitioning was measured, including phase forming components’ concentrations, tie line lengths, phase volume ratio, supernatant dilution, process temperature and halogen salt supplementation. Partitioning coefficients up to 78 in the bottom phase were achieved with yields of over 90%. Tie line length and phase volume ratio had significant effect on enzyme partitioning.