Thermally stable titanium dioxide nanoparticles (TiO2 NPs) doped with erbium ions (Er3+) are characterized by uniformity, low excitation energy, and high surface area. The impregnation methodology was used to enhance the optical properties of TiO2 NPs impregnated with various Er3+ ion contents. The synthesized Er3+/TiO2 samples were characterized by energy dispersive X-ray (EDX), metal mapping, UV-Visible spectrum, field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The Er3+ ions, per our findings, were well-distributed on the TiO2 surface of the anatase phase and there was an insignificant difference in particle size, but there was no change in the particle shapes of the Er3+/TiO2 NPs structure. The maximum band gap degradation occurred with 1.8 wt % of Er3+/TiO2, where the energy gap degraded from 3.13 to 2.63 eV for intrinsic TiO2. The synthesized Er3+/TiO2 samples possess predominantly finely dispersed erbium ion species on the surface. Er3+ ions agglomeration on the surface increased with increasing ions in each sample. We found that 0.6 wt/vol % of Er+3/TiO2 is the best optical coating and produced satisfying results in terms of blocking the transmittance of blue wavelength without reducing the image quality.
This paper presents the preliminary steps required for conducting experiments to obtain the optimal operating conditions of a hybrid impeller mixer and to determine the residence time distribution (RTD) using computational fluid dynamics (CFD). In this paper, impeller speed and clearance parameters are examined. The hybrid impeller mixer consists of a single Rushton turbine mounted above a single pitched blade turbine (PBT). Four impeller speeds, 50, 100, 150, and 200 rpm, and four impeller clearances, 25, 50, 75, and 100 mm, were the operation variables used in this study. CFD was utilized to initially screen the parameter ranges to reduce the number of actual experiments needed. Afterward, the residence time distribution (RTD) was determined using the respective parameters. Finally, the Fluent-predicted RTD and the experimentally measured RTD were compared. The CFD investigations revealed that an impeller speed of 50 rpm and an impeller clearance of 25 mm were not viable for experimental investigations and were thus eliminated from further analyses. The determination of RTD using a k-ε turbulence model was performed using CFD techniques. The multiple reference frame (MRF) was implemented and a steady state was initially achieved followed by a transient condition for RTD determination.
Radiotracer experiments are carried out in order to determine the mean residence time (MRT) as well as percentage of dead zone, V dead (%), in an integrated mixer consisting of Rushton and pitched blade turbine (PBT). Conventionally, optimization was performed by varying one parameter and others were held constant (OFAT) which lead to enormous number of experiments. Thus, in this study, a 4-factor 3-level Taguchi L9 orthogonal array was introduced to obtain an accurate optimization of mixing efficiency with minimal number of experiments. This paper describes the optimal conditions of four process parameters, namely, impeller speed, impeller clearance, type of impeller, and sampling time, in obtaining MRT and V dead (%) using radiotracer experiments. The optimum conditions for the experiments were 100 rpm impeller speed, 50 mm impeller clearance, Type A mixer, and 900 s sampling time to reach optimization.