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High temperature gas desulfurization (HTGD) is the main process for hydrogen sulphide removal from hot gases. Currently leading regenerable desulfurization sorbents are based on ZnO–TiO2 system. This work presents structural and textural modifications of ZnO–TiO2 based sorbents by Al2O3 addition in order to ensure high temperature mechanical support. Sorbents with composition Zn(2-x)Al2xTi(1-x)O4 (x = 0, 0.25, 0.5, 0.75, 1) were prepared by sol-gel process followed by thermal treatment. Nanocrystalline powders were produced at moderate sintering conditions (500 °C, 2 h). Depending on the initial ZnO:TiO2:Al2O3 molar ratio, zincite (ZnO), brookite (TiO2) as well as gahnite (ZnAl2O4) solid solution were formed. Al2O3 induced textural modifications, rising specific surface area from 34 to 90 m2g-1. The sorbent sulphidation performance was tested using newly developed procedure comprising batch sulphidation process. Sorbent with composition Zn1.75Al0.5Ti0.75O4 was found to possess the highest sulphidation reactivity, i.e. sulphur removal efficiency.

Fertilizer and detergent manufacturing, food processing, cosmetic and especially pharmaceutical industries use fluid-bed coating technology to improve properties like color, taste, composition, flowability and compressibility of various particulate systems. In this paper, the coating process of placebo pharmaceutical system is studied. Tablets of microcrystalline cellulose (MCC) were coated in a batch fluid-bed process system with a Wurster tube. Aqueous solution of hydroxypropyl methylcellulose (HPMC) was used as coating formulation that has to be deposited on the surface of placebo ingredient. Ultimate goal would certainly be reaching high deposition uniformity on the surface of MCC tablet with minor loss of coating agent. This research deals with detection of the process conditions and properties of inlet process stream that will lead underlying phenomena in desired direction and result in a collective of tablets with high coating uniformity. The effects of temperature of inlet air stream, the flow rate of coating medium as process variables, and concentration of HPMC solution as the property of the inlet process stream on the coating efficiency are defined as well. Contributions of macroscopic variables in forming the process response, coating efficiency, were statistically determined by using two-level factorial design. Statistical analysis indicates a significant effect of the inlet air temperature on the coating efficiency. Additionally, adhesion of coating agent in the deposition process has been considered. Measuring of contact angle with goniometer technique suggests a notable compatibility of MCC tablets and aqueous solutions of HPMC in their adhesion to tablet coated with HPMC film.

The drag coefficient is important hydrodynamic characteristic of the motion of particles in both, Newtonian and non-Newtonian fluids, and possibilities of its evaluation based on mathematical equations are very significant. Development of mathematical model for estimating drag coefficient values is primarily based on measurement accuracy. The experiment was run using carboxymethylcellulose water solutions in concentration range 1-4 wt% with different rheological properties which were determined using RV-3 HAAKE Viscometer. Approximately 200 experimental results were obtained using spherical particles of different materials and diameters. Measurements of the falling velocities were carried out in a glass tube. An optical method of measuring was developed for this purpose. Laboratory device contains three printed boards. Two are identical and each consists of 7 photodiode photoreceiver pairs while third is used for connecting with computer. Photodiodes emit 2 mm wide IR ray towards photoreceivers and their outputs give TTL levels. Output signals from these two boards are connected with RS flip-flop on third board, and his output is connected to computer. This technique enables time measurement accuracy of 0,02 s. By comparison experimental drag coefficient values with those obtained using proposed model for pseudoplastic fluids (1), the value of mean relative deviation is 25 %. Our proposed mathematical model simplify correlation of correction factor vs. flow behaviour index and achieve better results in wide range of Reynolds number (RePS < 1000) that gives a value of mean relative deviation 15%.