Taner Tekin

Effect of ultrasound on the dissolution of colemanite in H2SO4

This paper deals with the dissolution of colemanite in sulfuric acid, in the absence and presence of ultrasound. By nonlinear regression analysis, a modified Avrami-typeA equation was fitted to kinetic data and the activation energy was found to be 30 kJ/mol in both cases. The effect of ultrasound is on the pre-exponential factor A in the Arrhenius equation. An empirical relation is also given, which relates the rate constant to ultrasound power.

Effect of ultrasound on the dissolution kinetics of phosphate rock in HNO3

Ultrasound is known to enhance solid/liquid reactions. This paper deals with the investigation of the dissolution of phosphate rock in nitric acid, in the absence and presence of ultrasound. The reaction is first-order with respect to H+ and activation energy equal to 16 kJ/mol in both cases. The effect of ultrasound is on the pre-exponential factor A. An empirical relation is given, which relates rate constant to ultrasound power.

Exergy and structural analysis of raw juice production and steam-power units of a sugar production plant

In this paper, exergy analysis successfully assesses the true thermodynamic efficiency of chemical processes. It also indicates the plant irreversibility distribution among plant components, revealing those which contribute most to plant inefficiency. A structural analysis is also performed to determine the effects of some operating parameters on the local irreversibility rates with respect to the overall plant irreversibility rate. This study deals with the application of exergy analysis to raw juice production and the steam-power units of the sugar production plant from sugar beet. The structural bond coefficients of the some operating system parameters are calculated. It is concluded that if the optimal values determined for the operating system parameters in this work were chosen, the total exergy loss of the plant would decrease 4.21%.

Use of ultrasound in the dissolution kinetics of phosphate rock in HCl

Abstract The dissolution kinetics of phosphate ore in HCl solutions is investigated in the absence and presence of ultrasound. The particle size, reaction temperature, acid concentration and amplitude of ultrasound power were chosen as parameters. The reaction is first order with respect to H + and activation energy equal to 18 kJ/mol in both cases. The effect of ultrasound is on the pre-exponential factor A. An empirical relation is given which relates rate constant to ultrasound power.

Exergy analysis of the sugar production process from sugar beets

The exergy analysis of chemical processes is a powerful tool for process optimization, taking into account both ecological and economical restrictions. This study deals with the application of exergy analysis to the industrial process of production of white refined sugar beets. Energy and exergy band diagrams are presented. The exergetic performance of the process is calculated. The locations and magnitudes of exergy losses are determined and possible improvements are discussed.

EXERGY LOSS MINIMIZATION ANALYSIS OF SUGAR PRODUCTION PROCESS FROM SUGAR BEET

Exergy loss or equivalent entropy generation minimization is a powerful tool to design and operate processes which use energy as well as natural resources more efficiently. Two techniques, namely; approximate optimization analysis and structural analysis may be helpful to simplify the detailed optimization task. This study considers the application of these techniques to the process of sugar production from sugar beet.

Modelling of Oxygen Transfer Rate in Diffused-Air Aeration Tanks

The oxygen transfer rate, which is the most energy demanding unit process, is an essential factor in the operation of an activated sludge plant. Energy conservation effort has been directed at designing high efficiency and optimal air diffusers for use in activated sludge aeration tanks. This paper proposes a model for oxygen transfer rate in diffused air systems. The model parameters were found by means of nonlinear regression analysis, using plant data given in the literature. The proposed model may be useful for the preliminary design of diffused air aeration tanks.

Increasing of Photocatalytic Performance of TiO2 Nanotubes by Doping AgS and CdS

Highly ordered titanium nanotubes (TiO2 NTs) photocatalyst was prepared by the anodic oxidation method, and AgS, CdS, and AgS/CdS nanoparticles were doped on the surface of TiO2 NTs by the successive ion adsorption and reaction (SILAR) method. The photocatalysts were characterized by SEM, EDS, XRD, and potentiostat system. The SEM and EDS analyses respectively show that the average outer diameter of prepared photocatalysts is in the range of 50–120 nm, and the presence of Ti, O, Ag, and Cd is successfully proved. The photocatalytic properties of TiO2 NTs and doped TiO2 NTs were studied by measuring the degradation of Methylene Blue (MB) solution. The experimental results show that AgS/CdS/TiO2 photocatalyst exhibited most efficient photocatalytic activity with 340 µA/cm2 photocurrent value. AgS/CdS/TiO2 NTs photocatalyst shows up to 22.20% higher than TiO2 NTs, 16.42% higher than CdS/TiO2 NTs, and 4.3% higher than AgS/TiO2 NTs.

Increasing the conversion fraction of sulfur to sodium thiosulfate with the ultrasound energy

The usage of ultrasound has gained popularity in the recent years. Ultrasonic processing means blasting liquids, usually water, with very intense sound at high frequency, producing very well mixed powerful chemical and physical reactions. This paper deals with the investigation of the effect of ultrasonic energy on the conversion fraction of sulfur in the production reaction of sodium thiosulfate which was obtained from sulfur and Na2SO3 solution. Concentration of Na2SO3 solution parameter was chosen as the constant parameter. The experiments were performed with various amplitudes of ultrasound power and in the absence and presence of ultrasound energy in various temperatures with various particle sizes. The results indicate that the conversion fraction values increase in the presence of ultrasound energy and increase at high amplitude values.