Transesterification of waste fryer grease (WFG) containing 5–6 wt.% free fatty acid (FFA) was carried out with methanol, ethanol, and mixtures of methanol/ethanol maintaining the oil to alcohol molar ratio of 1:6, and initially with KOH as a catalyst. Mixtures of methanol and ethanol were used for transesterification in order to use the better solvent property of ethanol and rapid equilibrium using methanol. Formation of soap by reaction of FFA present in WFG with KOH instigated difficulty in the separation of glycerol from biodiesel ester. To untangle this problem, two-stage (acid and alkali catalyzed) method was used for biodiesel synthesis. More than 90% ester was obtained when two-stage method was used compared to ∼ 50% ester in single stage alkaline catalyst. In the case of mixed alcohol, a relatively smaller amount of ethyl esters was formed along with methyl esters. Acid value, viscosity, and cetane number of all the esters prepared from WFG were within the range of the ASTM standard. Esters obtained from WFG showed good performance as a lubricity additive. 相似文献
A series of alkali metal (Li, Na, K) promoted alkali earth oxides (CaO, BaO, MgO), as well as K2CO3 supported on alumina (Al2O3), were prepared and used as catalysts for transesterification of canola oil with methanol. Four catalysts such as K2CO3/Al2O3 and alkali metal (Li, Na, K) promoted BaO were effective for transesterification with >85 wt% of methyl esters. ICP-MS analysis
revealed that leaching of barium in ester phase was too high (~1,000 ppm) when BaO based catalysts were used. As barium is
highly toxic, these catalysts were not used further for transesterification of canola oil. Optimization of reaction conditions
such as molar ratio of alcohol to oil (6:1–12:1), reaction temperature (40–60 °C) and catalyst loading (1–3 wt%) was performed
for most efficient and environmentally friendly K2CO3/Al2O3 catalyst to maximize ester yield using response surface methodology (RSM). The RSM suggested that a molar ratio of alcohol
to oil 11.48:1, a reaction temperature of 60 °C, and catalyst loading 3.16 wt% were optimum for the production of ester from
canola oil. The predicted value of ester yield was 96.3 wt% in 2 h, which was in agreement with the experimental results within
1.28%. 相似文献
Superhydrophobic and UV protective textiles are of growing interest from the last few decades. In this study, silica nanoparticles (SiO2) were synthesized by the sol-gel method. The synthesized silica nanoparticles were applied on nylon knitted fabric by pad-dry-cure technique. The silica nanoparticles coating on fabric was modified by in situ deposition of zinc oxide (ZnO) followed by hydrophobic modification using sodium stearate (SS). The fabrics were characterized by Fourier transform infrared spectroscopy, X ray diffractometry, and scanning electron microscopy. The hydrophobic properties of the fabric were assessed by water contact angle measurement and ultraviolet protection properties of fabric were assessed by Australian/New Zealand Standard (AS/NZS 4399:1996). Modified fabric showed superhydrophobicity with water contact angle of 151°. The fabric also showed excellent ultraviolet protection with ultraviolet protection factor of 279.68. The fabric exhibited retention of hydrophobic and UV protection properties up to 10 washing cycles. 相似文献
The paper studies the motion of scrap tire shreds in a moving and stirred bed vacuum pyrolysis reactor. The reactor configuration is a novel concept. The pattern and the residence time distribution (RTD) of the particle motion in the reactor were investigated using tracers, for different feed rates and blade speeds. It was shown that the particle motion in the reactor is plug flow nature with intermediate dispersion (σ2 = 0.02—0.055). The mean residence time is in the range of 7—23 min, depending on the speed of the blades and the feed rate. The ratio of mean particle speed and the speed of blades vm/vb varied between 0.03 and 0.07. 相似文献
Synthetic polymers are based on the use of crude oil as their raw material. Oil spillage takes place during production, storage, transportation and usage at the water bodies and land surfaces. This may be due to tanker disasters, wars, operation failures, equipment breaking down, accidents and natural disasters. The spilled oil into land, river or ocean imposes a major threat to the environment and endangers the aquatic life. To overcome this problem, oil sorbents are commonly used for cleaning the oil spills. In this paper, coir fibre which was obtained as a waste from coconut fruit was functionalized to increase its hydrophobicity and oil sorption capacity. The product so formed was characterized by FT-IR, TGA and SEM which confirmed grafting of butyl acrylate monomer onto the coir fibres. The effects of time, temperature and monomer concentration on the grafting of coir fibre and oil absorption capacity have also been investigated. Results demonstrated that the modified coir fibre absorbed fair amount of crude oil and studies also indicate that a simple squeezing was sufficient to remove most of the oil sorbed by the fibres so that the sorbents can be reused several times for oil spill clean-up. 相似文献
Drug nanocrystals are known to increase the solubility of Biopharmaceutics Classification System (BCS) class II and IV drugs. SmartCrystals are the second generation nanocrystals with particle size of less than 100 nm and increased the stability and solubility of drug and drug product. The combinative methods adopted for the preparation of SmartCrystals are reported to shorten the processing time to reduce the particle size of the drug. This study was carried out with the aim to prepare nanosuspensions of aprepitant and ibuprofen using two pretreatment methods, precipitation and ball milling in a combination of high-pressure homogenisation (HPH). Ball milling and precipitation resulted in nanosuspensions having a particle size less than 1 µ, which were subjected to high HPH. HPH further led to a reduction in the particle size. However, the precipitation method failed to reduce the size of ibuprofen particles to 1 µ. 相似文献
The loss of zero-voltage-switching (ZVS) of active switches has been a serious limitation of full-bridge (FBZVS) converters.
Many techniques have been proposed in the past to extend the range of ZVS operation over the wider and also the full range
of operation. However, in these techniques ZVS is achieved at the expense of additional conduction loss in active switches
and losses in the auxiliary components. In this paper, the analysis for the additional losses in various full-range FBZVS
DC-DC converters and their comparative evaluation is reported. Closed form expressions are derived for average value of device
currents and losses. The loss curves for various topologies are plotted and compared. The analytical results are found to
be consistent with the experimental efficiency tests performed on 500 W, 100 kHz prototype. It is concluded that a recently
proposed new topology has the least penalty of additional losses. 相似文献
Over the last decade, application of soft computing techniques has rapidly grown up in different scientific fields, especially in rock mechanics. One of these cases relates to indirect assessment of uniaxial compressive strength (UCS) of rock samples with different artificial intelligent-based methods. In fact, the main advantage of such systems is to readily remove some difficulties arising in direct assessment of UCS, such as time-consuming and costly UCS test procedure. This study puts an effort to propose four accurate and practical predictive models of UCS using artificial neural network (ANN), hybrid ANN with imperialism competitive algorithm (ICA–ANN), hybrid ANN with artificial bee colony (ABC–ANN) and genetic programming (GP) approaches. To reach the aim of the current study, an experimental database containing a total of 71 data sets was set up by performing a number of laboratory tests on the rock samples collected from a tunnel site in Malaysia. To construct the desired predictive models of UCS based on training and test patterns, a combination of several rock characteristics with the most influence on UCS has been used as input parameters, i.e. porosity (n), Schmidt hammer rebound number (R), p-wave velocity (Vp) and point load strength index (Is(50)). To evaluate and compare the prediction precision of the developed models, a series of statistical indices, such as root mean squared error (RMSE), determination coefficient (R2) and variance account for (VAF) are utilized. Based on the simulation results and the measured indices, it was observed that the proposed GP model with the training and test RMSE values 0.0726 and 0.0691, respectively, gives better performance as compared to the other proposed models with values of (0.0740 and 0.0885), (0.0785 and 0.0742), and (0.0746 and 0.0771) for ANN, ICA–ANN and ABC–ANN, respectively. Moreover, a parametric analysis is accomplished on the proposed GP model to further verify its generalization capability. Hence, this GP-based model can be considered as a new applicable equation to accurately estimate the uniaxial compressive strength of granite block samples.