Preparation of the Carbonized Sorbents
The process of sample carbonization was carried out under isothermal conditions. Modification of the samples was carried out using a rotating reactor in an inert medium at 100-900°C, argon feed rate of 50 cm3/min, and contact time of 60 min. A reduced fraction [d = 4 mm] was used in the experiment, which was placed into the reactor. The installation diagram is shown in Fig. 2.1.
Figure 2.1 Diagram of installation for carrying out carbonization of plant and mineral raw materials.
Culture Conditions for Microbial Cells
Wort agar (6 В wort density, pH 6-7, 2% agar) was used as a nutrient medium for cultivating yeast, meat peptone agar for bacteria. The media were sterilized at 119°C (1 atm), 30 min. The inoculum was prepared as follows: cells taken from the wort agar slope were subcultured onto solid nutrient media (wort agar, meat peptone agar) in Petri dishes and cultivated in an incubator. They were further separated from the medium and washed with sterile isotonic solution by centrifugation at 5.000 rpm for 7 min. Cell suspension used in experiments was prepared in isotonic solution, and its optical density was adjusted to 0.6-0.8 units. Yeast cells were cultivated at 28°C for 48 h, the bacteria at 29°C for 24 h.
Examination of Hydrophilic-Hydrophobic Properties of Microbial Cell Walls
Cell wall hydrophobicity was determined according to the Rosenberg method as modified by Nikovskaya , which is based on the dependence of the partition coefficient of microbial cells between the hydrophilic and hydrophobic phases on the degree of hydrophobicity of microbial cell walls. To determine the partition coefficient, 1 ml of a cell suspension with a known optical density (a greater amount at 670 nm-0.400 units) was mixed with 0.5 ml of the test hydrocarbon (Vaseline oil), and after shaking and subsequent immiscibility phase, the optical density of the hydrophilic phase was again measured at 670 nm. The hydrophobicity coefficient was calculated according to Eq. (2.1):
where: dini is the optical density of the initial suspension; dexp is the optical density of the experimental samples after contact with a hydrophobic phase.