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In this paper, modelling and control of a batch bioreactor is studied. A main disadvantage of batch bioreactors compared to other types of bioreactors is their inability to introduce biological or/and chemical substances during operation. Therefore, possibility of bioreactor’s control by means of changing temperature was proposed, analyzed, and implemented. A new supplementary input/output dynamical mathematical model, which considers influence of heating and cooling on a bioprocess, was developed. On a basis of this model, a control system was designed and a method for tuning of the controller was suggested. Results show characteristics, applicability, and advantages of the presented approach.

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Based on an analysis of CO release transients in the case of non-simultaneous stepwise changed input quantities, two differential equations were defined that describe the influence of the two input quantities on the output quantity. The simulation results were verified by experiments. The proposed model can be used for a comprehensive analysis of the process that is being studied and for the design and synthesis of advanced control systems, which will ensure a controlled CO release at the industrial level. © 2018 Society of Chemical Industry.

Adhesives based on renewable resources have inferior efficiency compared to the synthetic ones. To improve the adhesive properties of soy protein isolate (SPI) adhesives, a new method of thermally modifying SPI was developed. The commercial SPI powder was thermally modified in a vacuum chamber at different temperatures (50, 100, 150, and 200°C). Thermally modified and unmodified SPI powders were dispersed in distilled water and stirred at 24, 50 or 90°C. Dispersions were prepared without and with pH adjustment to 10.0. The viscosity of the resulting adhesives was measured. Effective penetration and bond strength in longitudinal tensile shear were tested with bonded beech specimens. Regardless of the pH value and dispersion preparation temperature, SPI thermally modified at 150 and 200°C exhibited no adhesive properties, while adhesive bonding was achieved with SPI modified at 50 and 100°C. Adhesives without pH adjustment had viscosity below 28 mPas and exhibited no adhesive penetration. pH adjustment increased the viscosity and adhesive penetration, which improved the adhesive bond strength. Thermal modification at 50°C resulted in improved wet shear strength, while the temperature of 100°C deteriorated it. Increased dispersion preparation temperature to 50°C increased wet shear strength, while temperature of 90°C decreased it. The combination of thermal modification at 50°C, dispersion preparation at 50°C, and pH increase resulted in an adhesive with the highest shear strength.

The model glycoside compound quercetin-3-O-rutinoside (rutin) was subjected to subcritical water within the temperature range of 120-220 °C, and the hydrothermal degradation products were analyzed. Two kinetic models describing the degradation of this compound in two different atmospheres (N and CO), used for pressure establishment in the reactor, have been developed and compared. Reaction was considered a successive one with three irreversible steps. We confirmed that rutin degradation to quercetin follows first-order kinetics. At higher temperatures quercetin is further degraded in two degradation steps. Formations of 3,4-dihydroxybenzoic acid and catechol were described with the zero-order kinetic models. Reaction rate constants for hydrolysis of glycoside to aglycone in a CO atmosphere are higher compared to those in a N atmosphere, whereas at higher temperatures reaction rate constants for further two successive reactions of aglycone degradation are slightly lower in the presence of CO. The difference in reaction activation energies is practically negligible for both gases. Furthermore, degradation products of sugar moieties, that is, 5-hydroxymethylfurfural and 5-methylfurfural, were also detected and analyzed.

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