Ifa Puspasari

Drying Kinetics of Oil Palm Frond Particles in an Agitated Fluidized Bed Dryer

The drying kinetics of oil palm frond particles in a laboratory-scale agitated fluidized bed dryer were investigated under various operating conditions: inlet air temperature (50–80°C), superficial air velocity (0.6–1.0 m/s), bed load (200–300 g), and agitation speed (300–500 rpm). To study the effects of these variables on the drying time and drying rate, an experimental design using Taguchi orthogonal array was employed. Based on analysis of variance (ANOVA), the results indicated that inlet air temperature greatly affected the drying rate, followed by superficial air velocity and bed load. The effect of agitation speed on the drying rate was found to be small. The experimental drying kinetics data were compared with the values obtained from three different models, namely, the Page model, modified quasi-stationary method (MQSM), and a new composite model. It was found that the proposed new model could satisfactorily predict the complete drying rate curve for the drying of oil palm fronds.

Drying of Citrus sinensis Peels in an Inert Fluidized Bed: Kinetics, Microbiological Activity, Vitamin C, and Limonene Determination

Citrus sinensis peel drying kinetics in a fluidized bed with inert material were investigated. Drying impact on microbiological activity as well as limonene and vitamin C content was also studied. Drying parameters studied were as follows: temperatures of 40°C, 50°C, and 60°C; air velocities of 0.73 m/s and 0.85 m/s; and orange peel:sand weight ratios of 1:0, 1:1, and 1:2. High temperatures, high air velocity, and the presence of inert material increased the drying rate. Nine thin-layer drying models were fitted to the experimental data of Citrus sinensis peels. The Midilli et al. model was found to be the most suitable model for describing the drying kinetics of Citrus sinensis peels. Vitamin C and limonene content were higher in the product dried using a fluidized bed than in the sun-dried product. Drying of Citrus sinensis peel in a fluidized bed also may reduce microorganism growth, increasing storage life.

Sǔenje čestica lišća uljane palme u sušari sa fluidizovanim slojem u prisustvu inertnih čestica

Drying characteristic of oil palm frond fibres was investigated in a fluidized bed dryer with the presence of inert particles. Sand was used as inert material. Effects of air temperature (60, 70 and 80oC), air velocity (0.79 and 0.85 m/s) and mass ratio of fibres to sand (1:0, 1:1 and 1:2) on the drying curves were investigated. The results showed that the shortest drying time was obtained with the highest air temperature, air velocity and fibres to sand mass ratio. The experimental drying data were fitted to nine existing drying models namely Lewis, Page, Modified Page, Henderson and Pabis, Logarithmic, Two-term, Two-term exponential and Wang and Singh models and a proposed new model. The goodness-of-fit was determined based on the values of r2, c2 and RMSE. The results showed that the best quality of the fit was obtained using the proposed model. The new model was also validated for the superheated steam drying of oil palm empty fruit bunch from other work.

Comparative Study on the Microstructure and Photoluminescence Properties of SnO2 Nano Particles Prepared by Different Methods

This study presents comparisons between the morphologies and photoluminescence properties of tin oxide (SnO2) nanoparticles prepared by two methods, namely the sol gel and the co-precipitation methods. The characteristics of the particles were analyzed using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The particles prepared using the sol-gel method have a finer particle size and more spherical shape. However, no significant difference was observed in terms of morphology and homogeneity in the samples produced by either the co-precipitation or sol-gel methods. In contrast, the photoluminescence study shows that the emission peak for powder prepared using the sol-gel method was higher than that of the co-precipitation method.