• DETERMINATION OF SURFACTANT EFFECTIVE DIFFUSION COEFFICIENT USING INVERSE PROBLEM FOR WARD-TORDAI EQUATION

    Mathematical Modeling, Vol. 2 (2018), Issue 3, pg(s) 119-121

    The main purpose of the study was to assess the usability of a new calculation algorithm for determining the surfactants effective diffusion coefficient. The adsorption of a mixture of non-ionic surfactants onto flat water-air interface was considered. Presented algorithm is composed of a two parts: Ward-Tordai equation solver based on Nyström method for integral equations and golden ratio optimization method used in inverse problem. In the investigation the Langmuir model of an isotherm was assumed. Presented algorithm was successfully used to determine the non-ionic surfactant – Nafol 810D (BRENNTAG) effective diffusion coefficient in the diffusion controlled adsorption process.

  • PREPARATION AND CHARACTERIZATION OF NANOSTRUCTURED FERRIC HYDROXYPHOSPHATE ADJUVANTS

    Industry 4.0, Vol. 3 (2018), Issue 6, pg(s) 308-311

    This article describes part of the results obtained during the development of a new generation of vaccine adjuvants based on nanostructured hydroxyphosphates of tunable composition and physicochemical characteristics. Colloidal gels of ferric hydroxyphosphates of various iron/phosphate ratios were prepared by precipitation techniques, sterilized by autoclaving and analyzed by transmission electron microscopy (TEM) and dark-field optical microscopy. The obtained materials were composed of a network of amorphous nanoparticles (<20 nm in size) that were aggregated into micron-sized structures in physiological saline. Preliminary adsorption experiments indicated the ability of the obtained materials to adsorb protein substances, which is an important prerequisite for their potential application as vaccine adjuvants and further optimization of the production process to achieve reproducibility of the physicochemical characteristics.

  • TECHNOLOGIES

    THE POSSIBILITY OF USING WASTE MOLD SAND FOR ADSORPTION OF ACETIC ACID

    Machines. Technologies. Materials., Vol. 11 (2017), Issue 1, pg(s) 30-32

    Possibility of using waste mold sand for removal of acetic acid from the aqueous solution was studied in this article. Green sand can be used several times in mold making. When the properties of green sand are not suitable for further use, it becomes waste. Waste mold sand was used in this article as an adsorbent for the removal of acetic acid from the aqueous solution. During the adsorption process, the influence of the amount of the adsorbent and contact time adsorbent/adsorbate (waste mold sand/acetic acid) on the capacity of the adsorption process was monitored. Amount of waste mold sand was varied from 25 to 125 g. Contact times were as follows: 15, 30 and 60 minutes. The obtained results indicate that the adsorption of acetic acid on the waste mold sand occurred at all used combinations of these parameters. However, for all used contact times, the greatest adsorption capacity is achieved when the ratio of waste mold sand/acetic acid was 25 g/100 mL. For all the used amount of adsorbent, the highest adsorption capacity, i.e. dynamic equilibrium was achieved very quickly, after 15 minutes. The obtained results are in accordance with the chemical composition of the waste mold sand.

  • WASTE MOLDING SAND AS AN AGENT FOR THE REMOVAL OF Cu(II) AND Zn(II) IONS FROM AQUEOUS SOLUTION

    Machines. Technologies. Materials., Vol. 9 (2015), Issue 4, pg(s) 12-14

    This article presents the application of non-hazardous waste molding sand from gray cast iron foundry as an inexpensive adsorbent for removal of Zn(II) and Cu(II) ions from aqueous solutions. The experiments were performed at room temperature using a multi solution (Zn + Cu) with concentration was 100 mg/l. The process of removal of Zn(II) and Cu(II) ions was monitored at different contact times of waste molding sand and metal ions. The experimental data were processed by two different kinetic theories. The pseudo-first-order and pseudo- second-order models were used for modeling the kinetic rates.

    Obtained results show that the waste molding sand has significant potential for the removal of Zn(II) and Cu(II) ions from aqueous solutions. Research shows that the removal of Cu(II) ions was better than removal of Zn (II) ions. It is possible to conclude that the mutual competition of Cu(II) and Zn(II) ions for adsorption sites affect the intensity of their removal.

  • MATHEMATICAL MODELLING OF TECHNOLOGICAL PROCESSES AND SYSTEMS

    TRANSFER PROCESSES IN INDUSTRIAL COLUMN APPARATUSES

    Mathematical Modeling, Vol. 1 (2017), Issue 1, pg(s) 23-27

    The paper is a presentation of the monography “Chr. Boyadjiev, M. Doichinova, B. Boyadjiev, P. Popova-Krumova, Modeling of Column Apparatus Processes, Springer-Verlag, Berlin Heidelberg, 2016, pp. 313. A new approach to modeling the mass transfer processes in industrial column apparatuses, in the physical approximations of the mechanics of continua, is used for the creation of convection-diffusion and average-concentration models. The models of chemical, absorption, adsorption and catalytic processes are presented.