Creating a virtual device for processing the results of sorption measurements in the study of zinc oxide nanorods 154 D O I: 1 0. 15 82 6/ ch im te ch .2 02 0. 7. 4. 03 Maraeva E. V., Permiakov N. V., Kedruk Y. Y., Gritsenko L. V., Abdullin H. A. Chimica Techno Acta. 2020. Vol. 7, no. 4. P. 154–158. ISSN 2409–5613 Creating a virtual device for processing the results of sorption measurements in the study of zinc oxide nanorods E. V. Maraevaa*, N. V. Permiakova, Y. Y. Kedrukb, L. V. Gritsenkob, Kh. A. Abdullinс a Department of Micro-and Nanoelectronics, Saint Petersburg Electrotechnical University «LETI», Prof. Popova St., 5, Saint Petersburg 197376, Russsia b Satbayev University, Satpaeva St, 22, Almaty 050013, Kazakhstan c al-Farabi Kazakh National University, al-Farabi Ave, 71, Almaty 050040, Kazakhstan *email: jenvmar@mail.ru Abstract. The work is devoted to the creation of a virtual device (computer program) for processing the results of sorption analysis of nanomaterials, including for estimating the size of nanoparticles based on the specific surface area. The obtained evaluation results were compared with the scanning electron microscopy data. Photocatalytically active zinc oxide samples were chosen as the object of the study. Keywords: zinc oxide; nanorods; sorption measurements; virtual device; Received: 15.10.2020. Accepted: 09.12.2020. Published:30.12.2020. © Maraeva E. V., Permiakov N. V., Kedruk Y. Y., Gritsenko L. V., Abdullin Kh. A., 2020 Introduction Sorption analysis methods, as a rule, are used to characterize porous materials at  the  mesoporous (diameter 2–50  nm), as  well as  microporous (di- ameter ≤ 2  nm) levels. However, such a characteristic of the material as the spe- cific surface area, determined on the ba- sis of  analysis of  inert gas adsorption isotherms, in  some cases characterizes not only the  surface development due to  the  porous structure of  the  mate- rial, but also the  surface of  the  particles of the fragmented phase of the dispersed system. In this case, the data of a sorption study provide an express estimation of the siz- es of  nanoparticles, while the  sorption analysis methods have some advantages over other methods. Such advantages are the possibility of studying a large amount of material in one step (unlike local meth- ods where individual sections of the sam- ple are analyzed and the results of the study are averaged), as  well as  the  possibility of studying materials with high roughness, where other methods of surface analysis are not applicable or undesirable. The  aim of  this work was to  create a virtual device (computer program) for processing the results of sorption analysis of nanomaterials, including for assessing the size of nanoparticles based on the spe- cific surface area determined by the stand- ard BET method. As the object under study 155 photocatalytically active zinc oxide samples [1] obtained by annealing zinc acetate di- hydrate (CH3COO)2Zn∙2H2O in a muffle furnace were chosen. Experimental ZnO nanoparticles (NPs) were syn- thesized by  annealing zinc acetate dihy- drate (CH3COO)2Zn∙2H2O in  a  muffle furnace at  temperatures of  400  °C and 700 °C; the annealing time was 2, 4, and 10 hours. Zinc acetate was placed in a ce- ramic crucible covered with a ceramic lid. The mass of the obtained ZnO NPs sample was from a quarter to a third of the mass of zinc acetate. According to [2], the main weight loss occurs due to the combustion of acetone ((CH3)2CO) and carbon dioxide (CO2) in the precursor. Particle sizes were determined based on the  processing of  sorption analysis data implemented on a Sorbi MS device, which allows one to study the parameters of the porous structure of nanomaterials [3], including determining the size distri- bution of mesopores and specific surface area. The obtained evaluation results were compared with the data of scanning elec- tron microscopy. To develop a virtual program, the La- bView environment was used. The input to the analysis was a fragment of the ad- sorption isotherm of the selected inert gas on the test sample, the density of the test material, and the  aspect ratio of  the  na- norods. Results and discussion In  this work, five types of  zinc oxide samples were investigated. The  parame- ters of their heat treatment and the results of determining the specific surface area are shown in Table 1. The  data presented in  Fig.  1 were the initial ones for determining the particle sizes, which was carried out in two stages. The first stage was to determine the spe- cific surface according to  the  method of Brunauer, Emmett, Teller (SBET, Table 1). At the second stage, the average particle size was determined from the specific sur- face area in the framework of the model that the particles are nanorods with a given ratio of length and diameter L/D. The L/D ratio was selected on the basis of processing the experimental data of scanning electron microscopy, individually for each series of samples obtained by varying the anneal- ing modes. Fig. 1. Plots of adsorption isotherms for samples 1–5 Table 1 ZnO specific surface area vs. heat treatment temperature and duration № Heat treatment parameters SBET, m 2/g T, °C t, hours 1 400 2 13 2 400 4 9 3 400 10 10 4 700 2 5 5 700 4 5 156 Fig. 1 shows the nitrogen adsorption isotherm for a series of zinc oxide samples 1–5. According to the data of scanning elec- tron microscopy, the particles had a rod- like shape, and it was noted that the sam- ples synthesized at 400 °C had a shorter length and thickness than those obtained at 700 °C with the corresponding annealing duration. For example, Fig. 2 shows SEM images of the surface of a samples 1 and 4, and Table 2 shows the results of processing the  experimental SEM data for all types of samples. The diameter of the nanorods was cal- culated according to the formula: BET 4 2n D n S + = ρ⋅ ⋅ (1) where n — the aspect ratio, ρ — the den- sity, SBET — specific surface area of the ma- terial. Fig.  3 shows for example a  fragment of a block diagram (graphic code) of a pro- gram that calculates a  fragment of  na- norods for a given aspect ratio n. To calculate the size of the core particles by the sorption method, we used the ap- proximation that the diameter of the rod D refers to its height L according to the data presented in Table 2. The results of the sorp- tion analysis are presented in Table 3. Table 2 ZnO particle characteristics № Thickness D, nm Length L, nm average L average D n = L/D 1 43–81 300–539 420 63 7 2 54–88 400–690 545 71 8 3 48–88 400–688 544 66 8 4 80–136 260–400 330 98 3 5 108–113 109–358 234 111 2 Fig. 2. Morphology of ZnO samples obtained during annealing of zinc acetate in the atmosphere, annealing for 2 hours at temperatures: a — 400 °С sample 1, b — 700 °С sample 4 157 As can be seen from Table 3, the diame- ter of the rods will vary from 50 to 190 nm, and its height — from 0.4 to 0.7 microns, depending on the conditions of receipt. It was noted that the  height and diameter of the rods, determined by SEM and sorp- tion data, differ significantly for some samples. One possible reason is the recrys- tallization of the material during anneal- ing. It is likely that the annealing process changed the density of the material, which was the reason for the discrepancy between the data of sorption analysis and SEM for 2, 4, and 5 samples. Another reason may be the heterogeneity of particles in size and shape in the samples. Conclusions Series of photocatalytically active zinc oxide samples were studied. According to the data of scanning electron microscopy, it was found that the particles have a rod- shaped shape, while the  heat treatment conditions significantly affect the size and aspect ratio of the nanorods. A program has been developed that automates the process of calculating the size of nanorods based on sorption analysis data. The program can also be used to analyze nanoparticles of a dif- ferent shape, however, keep in mind, that several assumptions are the basis of the cal- culations: all particles are the same in size and shape (if it is, for example, the shape of nanorods, then when calculating their diameter it is assumed that the aspect ratio of all the rods in the sample are the same); particles have no internal pores and cavi- ties. The program can be used for approxi- mate express analysis of particle sizes and in the educational process. Fig. 3. A fragment of a program’s block diagram for selecting an adsorbate gas, calculating the specific surface area and determining the size of nanorods according to sorption analysis Table 3 Sorption analysis results № Heat treatment parameters L, μm D, μm T, °C t, hours 1 400 2 0.402 0.057 2 400 4 0.693 0.087 3 400 10 0.576 0.072 4 700 2 0.521 0.174 5 700 4 0.38 0.19 158 References 1. Ualikhanov RE, Kedruk EYu, Gritsenko LV, Chichero J, Abdullin HA. 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