Journal of Engineering and Technological Sciences
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Dioscorea hispida Starch as a Novel Natural Coagulant in Textile Wastewater Treatment
Get PDFThe process of coagulation-flocculation using Dioscorea hispida starch as a natural coagulant was investigated for the purification of textile effluent from several dyeing and finishing mills. The major parameters tested were COD, turbidity, and color. Prior to conducting the experiments, the general physical characteristics of Dioscorea hispida starch were investigated. The optimal conditions, pH and coagulant dosage were assessed using a jar test. The results demonstrated that the Dioscorea hispida starch yield was 15.38% of Dioscorea hispida dry weight. Pulverizing of Dioscorea hispida mass also resulted in approximately 10-15% of impurities in the final product. The optimal pH of 7 resulted in maximum COD, turbidity and color reductions of 28%, 94% and 64% respectively. The optimum dosage of Dioscorea hispida starch of 2500 mg/L resulted in a maximum reduction of 22%, 93%, 63%, of COD, turbidity, and color, respectively. Overall, this study confirmed that the utilization of Dioscorea hispida starch as a natural coagulant offers a relatively good removal efficiency in textile wastewater treatment
Effectiveness of Oil Palm Frond Activated Carbon for Removing COD, Color and Fe from Landfill Leachate
Get PDFThis study examined the applicability of oil palm frond-activated carbon (OPF-AC) as adsorbent in the treatment of landfill leachate. OPF-AC was prepared by mixing granular OPF with an aqueous solution composed of distilled water and zinc chloride (ZnCl2) at different ratios. Batch experiment studies were carried out to investigate the optimum OPF-AC dosage as well as the optimum shaking time. The optimum condition was achieved at 1.2 g of OPF-AC dosage and 50 minutes of shaking time. The highest removals of COD, color and Fe (77%, 75% and 69%, respectively) were obtained at the optimum condition. Meanwhile, the adsorption capacities were 146.93 mg/g (COD), 56.43 mg/g (color) and 0.11 mg/g (Fe). The increase in adsorbent dosage also resulted in a larger free surface area and exchangeable binding sites. However, the unsaturation of adsorption sites during the adsorption process resulted in a slight drop in removal efficiency of COD, color, and Fe. Furthermore, due to the aggregation and overcrowding of adsorbent particles, the use of a greater amount of adsorbent dosage imposed particle interactions.
Hydrogenated Palm Fatty Acid Distillate as Raw Materials for Magnesium Stearate Alternatives
Get PDFPalm fatty acid distillate (PFAD) was used as raw material to produce solid lubricant, or anti-adherent, for confectionery or pharmaceutical products. To improve the degree of saturation, the PFAD was hydrogenated by using two methods: gaseous hydrogenation (GH) and catalytic transfer hydrogenation (CTH) using ammonium formate to produce hydrogenated PFAD (HPFAD). The HPFAD was saponified with MgO to produce magnesium salts of hydrogenated PFAD (Mg-HPFAD). The objective of this research was to investigate the effect of hydrogen concentration and reaction temperature on the iodine value of HPFAD and to investigate the characteristics of paracetamol tablets when using Mg-HPFAD as lubricant compared to commercial Mg-stearate. The HPFAD produced by CTH had a lower iodine value than the HPFAD produced by GH. The lowest iodine value was obtained after CTH using 3.6 M ammonium formate at 90°C. Paracetamol tablets with Mg-PFAD or Mg-HPFAD lubricant showed higher dissolution of active compounds with similar friability, frictiability, and hardness compared to paracetamol tablets with Mg-stearate
Preparation of Graphene Oxide from Expanded Graphite at Different Microwave Heating Times
Get PDFExfoliated graphite (EG) was prepared by mixing graphite with HNO3 and KMnO4 at weight ratio 1:2:1 using microwave heating at times 20, 60, 80 and 120 sec. Graphene oxide (GO) was then prepared using EG as precursor by the modified Hummer’s method. Atomic force microscopy (AFM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analyses showed successful conversion of EG into GO. The XRD results of the GO showed that the maximum interplanar distance (d-spacing) increased from 0.344 to 0.831 nm. The AFM showed a minimum thickness of 0.519 nm for a single layer of GO prepared from EG 80 sec. The XRD examination also showed an increase in the d-spacing between the GO layers after sonication compared to before sonication
Experiment-based Comparative Analysis of Nonlinear Speed Control Methods for Induction Motors
Get PDFField-oriented control (FOC) for induction motors is widely used in industrial applications. By using a fast and accurate torque controller based on a stator current controller it is possible to flexibly implement advanced speed control methods to achieve proper performance both in transient and steady-state states. In this study, a deadbeat controller was used for the current loop. The nonlinear methods used for the outer loop controller were backstepping, flatness-based control, and exact feedback linearization with state derivative. The dynamic responses of these three controls were compared through various experimental results. The advantages and disadvantages of the different control structures were analyzed and evaluated in detail. Based on this evaluation, an appropriate scheme can be specified when deployed in practice
Theoretical Study of Direct Carbon Dioxide Conversion to Formic Acid on Transition Metal-doped Subnanometer Palladium Clusters
Get PDFWe studied the direct conversion of CO2 to HCOOH through hydrogenation reaction without the presence of base additives on the transition metal-doped subnanometer palladium (Pd7) cluster (PdxM: M = Cu, Ni, Rh) by using a combination of density functional theory and microkinetic calculations. It was shown that the CO2 hydrogenation on Pd7 and Pd6M clusters are more selective towards the formate pathway to produce HCOOH than the reverse water gas shift pathway to produce CO. Inclusion of Ni and Rh doping in the subnanometer Pd7 cluster could successfully enhance the turnover frequency (TOF) for CO2 hydrogenation to formic acid at low temperature. The order of TOF for formic acid formation is as follows: Pd6Ni > Pd6Rh > Pd7 > Pd6Cu. This order can be explained by the trend of the activation energy of CO2 hydrogenation to formate (HCOO*). The Pd6Ni cluster has the highest TOF value because it has the lowest activation energy for the formate formation reaction. The Pd6Ni system also has a superior TOF profile for HCOOH formation compared to several metal surfaces in low and high-temperature regions. This finding suggests that the subnanometer PdxNi cluster is a promising catalyst candidate for direct CO2 hydrogenation to formic acid
Numerical Simulation of Damage in Sandwich Composite Panels Due to Hydrodynamic Impact
Get PDFThe float and hull are vital parts of amphibious planes and boats, respectively, as both have to absorb hydrodynamic impact due to interaction with water. Sandwich composite panels are commonly used for such applications and other impact-absorbing structures. Unfortunately, the failure mechanism of sandwich composite panels under hydrodynamic impact is very complicated, as it may consist of composite skin failure, core failure, and non-uniform delamination. Hence, a numerical study on the damage of sandwich composite panels under hydrodynamic load is necessary. In this study, numerical simulation implementing the Coupled Eulerian-Lagrangian (CEL) method was performed to observe the damage mechanism of sandwich composite panels. The CEL method combines the Lagrangian and Eulerian frames into one model. Thus, analysis of structure deformation and fluid motion can be performed simultaneously. The result of the current numerical simulation shows a fair agreement with the experimental results in the literature, which shows that the current methodology can represent the sandwich composite panel response in real-life conditions, especially before shear core failure initiates
Identification of Micro-plastic Contamination in Drinking Water Treatment Plants in Phnom Penh, Cambodia
Get PDFMicro-plastics (MP) contamination in drinking water has become a global concern. Its negative impacts on human health have been reported. This study identified the presence of MP in two different drinking water treatment plants (WTP) in Phnom Penh, Cambodia, and investigated their removal efficiency. Samples were collected from the inlet, sedimentation, sand filtration, and distribution tank to quantify the removal by each unit. An optical microscope and a fluorescence microscope were used to detect the MP in four size fractions: 6.5-20, 20-53, 53-500, and >500 µm. Fourier transform infrared spectroscopy (FT-IR) was used to identify the polymer type for particles with size fractions of 53-500 and >500 µm. The results showed that the MP counted in WTP1 were 1180.5 ± 158 p/L in the inlet and 521 ± 61 p/L in the distribution tank. In WTP2, the MP counted were 1463 ± 126 p/L in the inlet and 617 ± 147 p/L in the distribution tank. The smaller size fraction of 6.5-20 µm predominated at each sampling location. Fragments were the most abundant morphology compared to fibers in all sampling points of both plants. PET predominated and the overall percentages for the inlet tank were 28.8% and 26%, followed by PE with 27.1% and 20.8% in WTP1 and WTP2, respectively. Other common polymer types were PP, PA, PES, and cellophane, while all others accounted for less than 5%. The results of the study showed that a significant number of MP remained in the water distribution system
