Fuel cell system with sodium borohydride hydrogen generator for small unmanned aerial vehicles

A 100 W proton exchange membrane fuel cell (PEMFC) system with a sodium borohydride (NaBH₄) hydrogen generator was investigated for small unmanned aerial vehicles (UAVs). The performance of a cobalt–phosphorous/nickel foam catalyst was evaluated to determine the change in catalytic activity under real operating conditions. The response time increased owing to oxidation of the metals and accumulation of sodium; however, the catalyst remained active at high reaction temperatures. A NaBH₄ hydrogen generator with the catalyst was developed for a 100 W PEMFC system. The hydrogen generation rate was stable for 3 h, and the conversion efficiency was 97.8%. Finally, a 100 W PEMFC system with the NaBH₄ hydrogen generator was investigated for small UAVs. The maximum power and energy density of the PEMFC system were 95.96 W and 185.2 Wh/kg, respectively.     

Synthesis and use of a catalyst in the production of biodiesel from Pongamia pinnata seed oil with dimethyl carbonate

The preparation of sodium methoxide-treated algae catalysts and their activity in the transesterification of Pongamia pinnata seed oil by dimethyl carbonate were investigated. We also investigated the effect of the sodium methoxide-treated algae catalyst on the biodiesel yield. The development of sodium methoxide-treated algae catalysts can overcome most problems associated with dissolution in dimethyl carbonate. The products were analyzed using gas chromatography-mass spectroscopy to identify the fatty acid methyl esters in the biodiesel produced. The molar ratio of Pongamia pinnata seed oil to dimethyl carbonate in transesterification in the presence of the sodium methoxide-treated algae catalyst was observed to play a substantial role in this study, wherein the Pongamia pinnata seed oil conversion increased with increasing catalyst concentration. The highest percent conversion rate was 97%. With intense research focus and development, an ideal catalyst can indeed be developed for optimal biodiesel production that is both economically feasible and environmentally benign.     

Transesterification of hazelnut oil by ultrasonic irradiation

Ultrasonic irradiation is considered an effective way to increase mass transfer between immiscible liquid–liquid phases in a heterogeneous system leading to faster transesterification and higher yield and saving excess methanol and catalyst. In this study, the transesteri?cation of hazelnut oil with methanol and ethanol was performed in the presence of potassium hydroxide or sodium methoxide as a catalyst using two types of ultrasonic irradiation with a probe (20 kHz, 200 W) and a bath (35 kHz, 400 W); a conventional production method was also used. The reaction time, alcohol:oil molar ratio, catalyst type (KOH or NaOCH₃), and catalyst amount (wt.% of oil) were studied as experimental parameters. The highest methyl ester conversion was obtained as 98.12% by using ultrasonic probe at a 5:1 methanol:oil molar ratio with KOH 1 wt.% of oil as catalyst in 20-min reaction time at autogenous temperature. The application of ultrasonic irradiation by using a probe decreased the level of energy consumption, showing that this method may be a promising alternative compared with the conventional production method.     

Design and optimization of new La1−xCexNi1−yFeyO3 (x,y = 0–0.4) nano catalysts in dry reforming of methane

The paper reports the production of syngas from dry reforming of methane (DRM) over La_1?xCe_xNi_1?yFe_yO₃ (x, y = 0–0.4) perovskites. A series of La_1?xCe_xNi_1?yFe_yO₃ were designed by central composite design (CCD) and synthesized by a sol–gel auto combustion method. Artificial neural network (ANN) approach was used to determine the relationship between preparation and operational parameters on the performance of the catalysts in the DRM process. Nickel mole fraction, lanthanum mole fraction, calcination temperature, and reaction temperature were considered as input variables, and conversion of methane was considered as the output variable. An ANN model with nine neurons in the hidden layer was the suitable in predicting conversion of methane. The genetic algorithm (GA) was subsequently used to determine the optimal preparation condition for enhancing the conversion of methane. La_0.6Ce_0.4Ni_0.99Fe_0.01O₃ catalyst, calcined at 756°C was obtained to be the most active catalyst owing to the optimal composition of nickel and lanthanum in the catalyst formulation.     

Validation of a dynamic model of hydrogen permeation through Pd-based membranes

Pd-based membranes have been studied for pure hydrogen separation from syngas: in particular, a mathematical model of a Pd membrane for hydrogen separation has been developed.This model can be used in process and assessment studies of the parameters which characterize the mass transfer phenomena (such as: hydrogen permeability, surface coverage and limiting step). By coupling the permeation and water gas shift reaction kinetics, it can also be used to evaluate the performances of the membrane reactor. Further, it can be helpful to evaluate the best assembly and sizing of a H₂/CO₂ separation system.The model takes into account the kinetics of H₂ adsorption/desorption on Pd surface, the H₂ permeation into the palladium bulk and in the porous layer, and the kinetics of CO, CO₂, H₂O, O₂, H₂S competitive adsorption/desorption on Pd surface. It is also comprehensive of flux equations and bulk mass, momentum and energy balance.The results released by the model were compared to the experimental data during both the transient phase and the steady state conditions. A satisfactory agreement between model and experimental data was found.     

Decomposition of NaBH4 with self-regeneration of carbon-supported CoCl2 catalyst

In this study, economically favorable CoCl₂ catalysts at four different amounts were supported on activated carbon (AC) for NaBH₄ dehydrogenation. Supported catalyst could achieve hydrogen release for 2,060 cycles, which is equivalent to 103 days of uninterrupted operation. Slow and continuous hydrogen release was observed in all experiments. Even 1 g of NaBH₄ can carry 1.2 L of hydrogen, and in hydrolysis process, it liberates 2.5 L of hydrogen that indicates the decomposition of water. EDX analysis and reverse burette measurements show that CoCl₂ could be homogeneously distributed on and permanently joined to the support surface. Kinetic investigation of the dehydrogenation reaction fits zero order kinetics, and activation energy was calculated to be 48 kJ/mol.     

树脂固定床吸附含酚废水预测模型研究

针对应用于实际工业化的树脂固定床吸附研究较少,而与之相关的固定床吸附穿透曲线可以用来确定固定床吸附操作参数,为固定床的设计和实际操作提供指导。通过对恒定波振荡理论和吸附等温方程的联合,来预测固定床吸附穿透曲线;并研究了不同操作条件对大孔弱碱树脂吸附对硝基酚穿透曲线预测模型的影响。以期望为树脂固定床的设计和实际工业应用产生指导意义。     

Optimization of biodiesel production from waste cooking oil using ion-exchange resins

Waste cooking oil is a potential substitution of refined vegetable oil for the production of biodiesel due to the low cost of raw material and for solving their disposal problem. In this study, optimization of esterification process of free fatty acids in artificially acidified soybean oil with oleic acid has been carried out using methanol as an agent and ion exchange resin as a heterogeneous catalyst. The esterification reaction has been investigated based on the mass balance of the developed model. The model has been validated against experimental data and effects of temperature and catalyst weight have been analyzed. Thereafter, optimization process has been fulfilled for two different objective functions as conversion of acid oil and benefit. Optimization results indicated that the maximum conversion of acid is 95.95%, which is achievable at 4.48-g catalyst loading and reaction temperature of 120°C. Maximum benefit was obtained as US$0.057 per batch of reaction at a catalyst amount of 1 g and temperature of 120°C.     

树脂纳米零价铁催化过硫酸钠降解甲基橙的研究

采用树脂负载零价纳米铁（NZVI-resin）作为铁源,活化过硫酸钠,产生硫酸根自由基氧化降解偶氮染料甲基橙。考察了温度、NZVI-resin加入量、pH值及过硫酸钠的浓度等因素对甲基橙降解率的影响,并对其降解动力学规律作了初步探讨。结果表明：降解反应遵循准一级反应动力学,在pH=3.0、Fe0=0.2 g.L-1、Na2S2O8=1.33 g.L-1的条件下,30 mg.L-1的甲基橙溶液降解率为99.7%。     

Degradation of potassium formate in the unsaturated zone of a sandy aquifer

This paper presents results from a lysimeter experiment on the fate of potassium formate, an alternative deicing agent. The experiment was performed through the winter and spring to identify any thermal sensitivity in the transport and biodegradation of formate in the lysimeter. Ninety-eight percent of the total quantity of formate applied was degraded while percolating through the 1.7-m-thick unsaturated sand layer within the lysimeter. Concomitantly, the bicarbonate concentration of the percolating water increased. The low concentrations of nitrogen (0.02 mg L(-1)) and phosphorous (<0.002 mg L(-1)) in the percolated water, however, potentially limited microbial activity. During the study period, 99% of the applied potassium was retained in the lysimeter, and the ion exchange between the potassium and a variety of monovalent and divalent ions was assumed to be responsible for the leaching of barium, calcium, magnesium, and sodium from the soil material. Except for manganese, the concentrations of the studied metals in the percolated water did not exceed the threshold values set for drinking water by the Council of the European Union. By contrast, the application of potassium formate had a detrimental effect on the vegetation on the lysimeter. To conclude, formate was effectively degraded in the sandy lysimeter and its application did not cause major undesirable changes in the quality of the percolating water. Further research at field scale is, however, needed for instance on the biodegradation of potassium formate and on its impacts on roadside vegetation.     

Coliquefaction of coal and polystyrene in supercritical water

The coliquefaction of coal and polystyrene (PS) in supercritical water (SCW) was carried out in a 50-mL batch stainless steel autoclave reactor, and the effects of the polymer ratio by weight (10–40%), reaction temperature (633.5–703.5 K), and reaction time (30–120 min) were investigated. The main products were analyzed qualitatively by Fourier transform infrared spectroscopy and high-performance liquid chromatography. The results show that polystyrene stimulates coal liquefaction as a hydrogen donor, and the synergistic effects during coliquefaction in SCW were confirmed. The conversion reached a maximum of 62.26% after 60 min at 673.5 K. The phase behavior during coliquefaction was observed in a fused silica capillary reactor using a combined microscope and video recorder system.     

AN OBJECTIVE METHOD OF THUNDERSTORM FORECASTING FOR WASHINGTON NATIONAL AIRPORT,WASHINGTON, D.C.1

The literature was reviewed in order to determine the variables likely to be important in forecasting thunderstorms. A stepwise discriminant analysis was performed on these variables to determine those significantly related to thunderstorm occurrence. Eight variables were selected. These were then used to produce a forecasting equation by means of the linear discriminant analysis technique. This equation was then tested against the Showalter and Total Totals indexes for forecasting skill, and was found to have higher skill.     

An Investigation of Thermal Decomposition Behavior of Hazelnut Shells

Turkey has a drastic potential in terms of biomass energy and it would be of utmost importance for our energy mix if this huge amount of energy is to be utilized. Thermochemical conversion is the most dominant one among the energy conversion processes. The carbonization process is the key point in determining the kinetic parameters of the fuels utilized. Thereafter, the kinetic parameters obtained from carbonization would be utilized in designing the thermochemical conversion equipments. In this study, the thermal decomposition behavior of hazelnut shells was investigated via dynamical thermogravimetry (TG) under N₂ atmosphere. In order to determine the effects of heating rate and gas flow rate, the experiments were performed in four different heating rates of 5, 20, 50, and 100 K/min and two different nitrogen flow rates of 50 and 100 cm³/min. As the heating rate was increased, peak temperature was increased, maximum temperature shifted to the right (higher T zones) and the maximum rate of weight loss was increased. In addition, lignin decomposition temperature interval was decreased whereas; cellulose decomposition temperature interval was increased. Increasing the heating rate from 5 to 20 K/min, hemicellulose decomposition temperature interval was increased. Total weight loss was slightly increased by the increase of gas flow rate. Kinetic parameters were calculated according to Coats Redfern method. It was found that activation energies of thermal decomposition reactions of hazelnut shell varied between 1.30 and 32.19 kJ/mol.     

Clam shell catalyst for continuous production of biodiesel

Continuous flow transesterification of waste frying oil (WFO) with methanol for the biodiesel production was tested in a laboratory scale jacketed reactive distillation (RD) unit packed with clam shell based CaO as solid catalyst. The physiochemical properties of the clam shell catalysts were characterized by X-ray Diffraction (XRD), Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), and Energy Dispersive Atomic X-ray Spectrometry (EDAX). The effects of the reactant flow rate, methanol-to-oil ratio, and catalyst bed height were studied to obtain the maximum methyl ester conversion. Reboiler temperature of 65°C was maintained throughout the process for product purification and the system reached the steady state at 7 hr. The experimental results revealed that the jacketed RD system packed with clam shell based CaO showed high catalytic activity for continuous production of biodiesel and a maximum methyl ester conversion of 94.41% was obtained at a reactant flow rate of 0.2 mL/min, methanol/oil ratio of 6:1, and catalyst bed height of 180 mm.     

Biosorption of copper(II) and lead(II) onto potassium hydroxide treated pine cone powder

Pine cone powder surface was treated with potassium hydroxide and applied for copper(II) and lead(II) removal from solution. Isotherm experiments and desorption tests were conducted and kinetic analysis was performed with increasing temperatures.As solution pH increased, the biosorption capacity and the change in hydrogen ion concentration in solution increased. The change in hydrogen ion concentration for lead(II) biosorption was slightly higher than for copper(II) biosorption. The results revealed that ion-exchange is the main mechanism for biosorption for both metal ions. The pseudo-first order kinetic model was unable to describe the biosorption process throughout the effective biosorption period while the modified pseudo-first order kinetics gave a better fit but could not predict the experimentally observed equilibrium capacities. The pseudo-second order kinetics gave a better fit to the experimental data over the temperature range from 291 to 347 K and the equilibrium capacity increased from 15.73 to 19.22 mg g^?1 for copper(II) and from 23.74 to 26.27 for lead(II).Activation energy was higher for lead(II) (22.40 kJ mol^?1) than for copper(II) (20.36 kJ mol^?1). The free energy of activation was higher for lead(II) than for copper(II) and the values of ΔH* and ΔS* indicate that the contribution of reorientation to the activation stage is higher for lead(II) than copper(II). This implies that lead(II) biosorption is more spontaneous than copper(II) biosorption.Equilibrium studies showed that the Langmuir isotherm gave a better fit for the equilibrium data indicating monolayer coverage of the biosorbent surface. There was only a small interaction between metal ions when simultaneously biosorbed and cation competition was higher for the Cu-Pb system than for the Pb-Cu system. Desorption studies and the Dubinin–Radushkevich isotherm and energy parameter, E, also support the ion-exchange mechanism.     

Degradation of soil fumigants as affected by initial concentration and temperature

Soil fumigation using shank injection creates high fumigant concentration gradients in soil from the injection point to the soil surface. A temperature gradient also exists along the soil profile. We studied the degradation of methyl isothiocyanate (MITC) and 1,3-dichloropropene (1,3-D) in an Arlington sandy loam (coarse-loamy, mixed, thermic Haplic Durixeralf) at four temperatures and four initial concentrations. We then tested the applicability of first-order, half-order, and second-order kinetics, and the Michaelis-Menten model for describing fumigant degradation as affected by temperature and initial concentration. Overall, none of the models adequately described the degradation of MITC and 1,3-D isomers over the range of the initial concentrations. First-order and half-order kinetics adequately described the degradation of MITC and 1,3-D isomers at each initial concentration, with the correlation coefficients greater than 0.78 (r2> 0.78). However, the derived rate constant was dependent on the initial concentration. The first-order rate constants varied between 6 and 10x for MITC for the concentration range of 3 to 140 mg kg(-1), and between 1.5 and 4x for 1,3-D isomers for the concentration range of 0.6 to 60 mg kg(-1), depending on temperature. For the same initial concentration range, the variation in the half-order rate constants was between 1.4 and 1.7x for MITC and between 3.1 and 6.1x for 1,3-D isomers, depending on temperature. Second-order kinetics and the Michaelis-Menten model did not satisfactorily describe the degradation at all initial concentrations. The degradation of MITC and 1,3-D was primarily biodegradation, which was affected by temperature between 20 and 40 degrees C, following the Arrhenius equation (r2 > 0.74).     

Effect of calcination temperature on the application of sodium zirconate solid base catalyst for biodiesel production from Jatropha curcas oil

Influence of catalyst calcination temperature on the catalyst characteristics and catalytic transesterification of Jatropha curcas oil for biodiesel production was studied by using sodium zirconate (Na₂ZrO₃) solid base catalyst. Na₂ZrO₃ catalysts were prepared by impregnation method followed by calcination at temperatures of 700, 800, and 900°C. The prepared catalysts were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. Important parameters influencing the catalytic activity and fatty acid methyl ester yield were investigated. It was found that the increase in calcination temperature showed marked increase in activity due to the increased porosity and presence of tetragonal zirconia. Investigation of the reusability of the catalysts showed that the catalytic activity was retained even after five cycles of reaction.     

AN EVAPORATION EQUATION FOR AN OPEN BODY OF WATER EXPOSED TO THE ATMOSPHERE1

ABSTRACT Evaporation is identified as having two additive components: natural evaporation in the absence of wind and forced evaporation in the presence of wind. An evaporation equation is obtained for an open body of water exposed at the atmosphere by conversion of standard horizontal flat plate heat transfer relationships to a mass transfer or evaporation equation. For an average air temperature of 68°F, the final equation for evaporative heat flux is A comparison of numerical values predicted by the above equation is made with evaporation equations deduced from field measurements, and the agreement is favorable. The major differences between this equation and those previously developed are: a) the above equation was derived strictly from standard heat transfer expressions, and b) a dependency of average fetch and air temperature (through transport properties) is shown. This approach establishes the correct dependencies of the field parameters so that future experimental measurements will have a sound theoretical basis.     

对铁碳处理硝基酚废水的研究

铁碳降解水中难降解有机污染物的影响因素、最佳工艺参数及处理效果;初步探讨了氧化降解污染物的作用机理;通过分析污染物降解的中间产物,提出了污染物降解的可能途径.探讨了pH、铁碳用量、温度以及锰矿物的粒径等对处理效果的影响,在最佳的工艺条件下,CODCr的去除率达到95%以上,TOC测定表明：大部分硝基酚被氧化降解为H2O和CO2.对硝基酚的降解途径主要是微电解将对硝基酚还原为对氨基酚,对氨基酚在酸性条件下被软锰矿氧化为H2O和CO2做探索性研究.     

Material flow and industrial demand for palladium in Korea

Material flow analysis (MFA) requires the use of reliable data. In intermediate or the end industries that lack field survey data or actual statistical data, the integrated material flow analysis methodology uses bottom–up flow analysis for primary and secondary resources, and top–down flow analysis for the distribution structure. By combining the advantages of the top–down and bottom–up methods, the Integrated Material flow Analysis Methodology (IMFAM) can overcome the limitations of each methodology. Using the IMFAM, this study surveyed the material flow of palladium, and a platinoid element used in Korea. Palladium is produced as a byproduct in the copper refining process in Korea, and about 80% of used palladium as a three-way catalyst (TWC), i.e., an exhaust gas purifying system for automobiles. As automobile production in Korea is expected to continually increase, the usage of palladium is also expected to increase. Moreover, the increase in the use of printed circuit board (PCB) plating solutions is expected to further increase the use of palladium.This MFA results well represent the flow of palladium in Korea and give a strategy to secure palladium steadily.