Numerical estimation of moisture content in spray dried juice powder

The moisture contents of powders is an important parameter that affects the quality and commercial value of spray dried products. The utility of predicted moisture content values from two droplet drying models were compared with experimental data for spray dried pineapple juice, using the Ranz-Marshal and its modified variants for the heat and mass transfer correlations. The droplet Diffusion model, using the Zhifu correlation, gave estimates with errors of about 8 at 165 °C, 9 at 171 °C, 26 at 179 °C and 2 at 185 °C. The Ranz-Marshal correlation also gave comparable results with this model while results using the Downing and modified Ranz-Marshall correlations widely diverged. The Energy balance model predicted completely dried juice particles, and short drying times, in contrast to the experimental data. The small error sizes of the Diffusion model improves on the wide error sizes of an earlier process model, making is useful as a first approximation choice, for spray drier design and simulation, especially for juices under comparable operating conditions

Significant effect of ph on photocatalytic degradation of organic pollutants using semiconductor catalysts

Photocatalytic is one of the inexpensive and non-toxic techniques for degradation of organic pollutants into harmless substances such as water and carbon dioxide. In this study, simple electrolysis method was used in preparation of Ag/TiO2 and α-Fe2O3/HY catalysts. The physicochemical properties of the catalysts were studied using XRD, FTIR, FESEM-EDX and surface area analysis. The pH of solution plays an important role in the photocatalytic degradation of organic pollutants which influences the surface-charge properties of the catalysts. Ag/TiO2 and α-Fe2O3/HY were used as catalyst on degradation of 2-chlorophenol (2-CP) and methyl orange (MO), respectively. The effect of pH on degradation of 2-CP and MO were investigated over a pH range from 2 to 9. Higher degradation of 2-CP and MO were obtained at pH 5 (74%) and pH 2 (80%), respectively. This finding might be explained by the amphoteric performance of the catalyst using point zero charge (pHZPC). The pHZPC for Ag/TiO2 and α-Fe2O3/HY was found to be at pH 6.3 and pH 7.2, respectively. Hence, the activities of the catalysts may have been affected by the existence of a strong electrostatic field between the positively charged catalysts surface and negatively charged 2-CP and MO caused a pH value lower than their pHZPC give greater degradation

Process simulation of pineapple juice spray drying

Pineapple juice is one of the known natural sources of bromelain, a bioactive compound beneficial to health. The dried powder has potential commercial value and is a convenient source of the juice drink. The quality of spray dried pineapple juice is dependent on the powder moisture content. Spray dried pineapple powders with low moisture contents were produced in a lab-scale spray dryer in this study. Powder production of 25% of total solids were obtained by use of DE6 maltodextrin to solids ratio of 0.41:0.59. A heat and mass transfer model of the spray drying process was implemented in Matlab and solved to determine its predictive utility. The simulation results showed agreement with experimental data at high inlet air temperatures but widely diverged at other air temperatures. The error size in predicted product moisture varied from 73% at 165 oC to almost zero at 185 oC while that for the predicted exit air temperatures varied from about 38% to zero over the same temperature range. Accuracy can be improved if transient heat effects, and sub models for the feed drying are included in the model

Sandwich structure polymer electrolyte membranes containing phosphotungstic acid immobilized electospun nanofibers

The advances in proton exchange membranes (PEM)s is critical for improving the performance of fuel cells [1]. Membranes compromising perfluorosulfonic acid polymers such as Nafion have been used extensively due to their desired conductivity and stability. However, these materials need to be saturated with water to obtain practical level of proton conductivity. There is a strong demand for the PEMs to work at lower relative humidity or under anhydrous conditions because the electrochemical reactions will be accelerated and water management of fuel cell will be simpler. Various designing strategies and advanced materials have been developed to mitigate for this issue without causing serious loss in proton conductivity or stability [2]. Among all, the introducing of inorganic proton conductors such as heteropoly acids have been considered widely. Generally, HPAs (such as phosphotungstic acid H3PW12O40, PWA) have a very strong Brønsted acidity approaching the superacid region (more acidic than Nafion) [3]. In this work, high level of PWA was self-anchored onto nylon electrospun nanofiberous sheet (Figure 1b). Sandwich structured proton conducting membranes were fabricate by assembling nanofibrous central layer with outer Nafion layers (Figure 1b). Since the PWA is attached to the polymer backbones, the risk of leaching out is minimized. Moreover, the significant synthetic versatility of the method helps to increase PWA immobilization level. As shown in the Figure 1c, proton conductivity of as high as 60 mS cm-1 at 30 °C was achieved which is comparable with Nafion 115. The durability of the proton conductivity of sandwiched membrane

An Equivalent Circuit Model of Miniature Double E-Shaped Meander Line Printed Monopole Antenna

An equivalent circuit model of the UHF miniature double E-shaped meander line printed monopole antenna is presented. The proposed antenna has a simple structure and small antenna size of 46.8 mm x 74 mm or 0.137 Lambda0 x 0.217 Lambda0 at 878 MHz resonant frequency. Advanced Design System (ADS) software is used to develop the antenna circuit model. Each section of the antenna structure is represented by the inductance and capacitance circuit with their values are depending on the width and length of the structure. The circuit model is developed based on common discontinuities in the microstrip line. The performance of the circuit model in terms of return loss is compared with the CST simulation for a validation. The printed monopole antenna is having similar radiation characteristics as an ideal wire monopole where it radiates uniformly in all directions

Electrooxidation of nitrite ions on gold/polyaniline/carbon paste electrode

Nitrite ions can penetrate from fertilizers into underground water and consequently contaminate the water and food sources. A facile two-step electrochemical method was used to fabricate gold/polyaniline/carbon paste electrode (Au/PAni/CPE) for nitrite sensing. The Au/PAni/CPE was visualized and characterized by scanning electron microscopy, energy-dispersed X-ray spectroscopy, X-ray diffraction and electrochemical methods. The electrocatalytic activity of bare CPE, PAni/CPE and Au/PAni/CPE toward the electrooxidation of nitrite was examined and compared via cyclic voltammetry. To obtain the optimal condition for fabrication of the electrode, the number of cycles in cyclic voltammetry for synthesis of polyaniline and the deposition time in potentiostatic deposition of gold were optimized with respect to the electrooxidation of nitrite. In a phosphate buffer solution (PBS, pH 7.0), the peak current was linear to the concentration of nitrite in the range from 3.8×10-5 M to 1.0×10-3 M with a detection limit of 2.5×10-5 M. The interference effect on the nitrite detection was also studied. The proposed method was also employed for the determination of nitrite in rain and lake water samples

Synthesis of activated carbon doped with transition metals for hydrogen storage

Carbon materials with high porosity and surface area such as activated carbons with a combination of metal possess great materials to obtain maximum hydrogen adsorption via the hydrogen spillover effect. The properties of activated carbon doped with metals (copper, nickel and palladium) were studied to evaluate the capacity of hydrogen sorption on the materials. Characteristics of the activated carbon doped with copper (AC-Cu), nickel (AC-Ni) and palladium (AC-Pd) were evaluated using particle density test, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and surface and pore analysis (BET). The performance of hydrogen adsorption of the materials was carried out at different pressures of 50, 100 and 150 psi. Characterization of the materials shows that FTIR spectroscopy manage to detect surface functional groups meanwhile the carbon structure and metal content was determined using XRD. BET analysis shows the presence of oxygen groups was decrease the specific surface area whereas the presence of transition metals had increased the surface area. Hydrogen adsorption test at 150 psi indicates that oxygen groups are not a good adsorption characteristic with only a maximum of 0.39 wt% of hydrogen was adsorbed compared to pristine activated carbon’s 0.42 wt% at 150 psi. The presence of transition metals, copper, nickel and palladium increased the overall hydrogen uptake with 0.52 wt%, 0.44 wt% and 0.62 wt% respectively at 150 psi

Thermodynamic and experimental explorations of CO2 methanation over highly active metal-free fibrous silica-beta zeolite (FS@SiO2-BEA) of innovative morphology

CO2 methanation is a novel way for climate change mitigation by converting CO2 into substitute natural gas. In this study, a highly active fibrous silica-beta zeolite (FS@SiO2-BEA) catalyst was prepared for CO2 methanation by a microemulsion process, and examined by N2 adsorption–desorption, field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and electron spin resonance (ESR) spectroscopy techniques. It was found that the FS@SiO2-BEA catalyst possessed a fibrous silica morphology, leading to high surface area (609 m2/g), oxygen vacancies, and basicity. A thermodynamic study was also carried out using Gibbs free energy minimization method, and it was found that low temperatures (25–350 °C) and high H2: CO2 ≥ 4 ratios have enhanced the CO2 methanation activity. The prepared FS@SiO2-BEA catalyst exhibited high CO2 conversion (65%), and CH4 selectivity (61%) with a space–time yield of 3.30 g gcat−1 h−1. The obtained experimental results highly followed the thermodynamic calculations

Small and Compact Double E-shaped Meander Line Monopole Antenna for Forward Scatter Radar Network

A small and compact printed monopole antenna can be obtained by introducing double E-shaped meander line patch backed by a partial ground plane. The double E-shaped meander line patch reduces the antenna resonant frequency so that the size of the antenna can be reduced for targeted frequency of 400 MHz specific for Forward Scatter Radar (FSR) Network. 77% size reduction of the antenna has been successfully achieved where the overall size of the proposed antenna is only 93.8 x 131 mm2 (0.125λ0 x 0.175λ0) compared to before it was reduced which is 190.7 x 276.3 mm2 (0.25λ0 x 0.368λ0). The size reduction is obtained without significant effects on other antenna performances. The proposed antenna produces high measured efficiency of 85.5% and measured gain of 0.3 dBi with an omnidirectional radiation pattern. A comprehensive parametric study is accomplished to obtain the best performances of the antenna. For a better understanding on the design characteristics, an equivalent circuit model is derived carefully