In order to propose an efficient concentration process for ethanol, efficiency of multi-stage reverse osmosis membrane processes which consist of membranes with various separation characteristics was evaluated with computer simulation. Specification of the process was as follows; initial concentration: 5wt%, concentration of product: 96wt%, yield: more than 95%. Permeate flux values of water and ethanol were calculated with membrane permeation equation based on the solution-diffusion model. Energy and cost (costs for membrane and energy) required for the concentration process were calculated with the computer simulation, and the process was optimized in order to minimize the cost required for the process. In the case of three-stage membrane process consisting of water-selective membrane and ethanol-selective membrane, optimum process designed by applying the highest separation factor among available membranes required 2.14 MJ/kg of energy, which was about one-fourth of the energy required in distillation process. And the cost required by the optimum process was estimated at 3.15 yen/kg. Further improvement in separation factor showed little effect on reduction in the cost. By adding one more stage and composing four-stage membrane process, both energy and cost could be reduced by about 30%.
Biodiesel fuel (BDF), biofuel made from natural oils and fats, is being regarded as a promising substitute to the petro-diesel fuel. An alkaline catalyzed alcoholysis process, to form fatty acid methyl esters (FAME) from vegetable oils, is widely used to produce BDF. This process, however, requires high costs for refining the products and recovering the catalysts. In this study, a new reactor was developed to produce FAME by blowing superheated methanol gas continuously into oils without using any catalysts. Effects of reaction temperature, methanol feed flow rate, operating pressure, stirring rate, and initial oil volume on the reaction rate were investigated. The experiment showed that the maximum outflow rate of FAME was occurred at reaction temperature of 290°C, increased with methanol feed flow rate and initial oil volume, but decreased with operating pressure and stirring rate. As a result, effects of reaction conditions on reaction rate were quantitatively evaluated, and necessary information required to improve the reactor design were indicated.
The determination of the lipid content of garbage compost by near infrared spectroscopy (NIRS) was investigated, because lipid content is known to be an inhibitor of plant growth and germination. The garbage compost samples, which were produced by electric garbage processors, were obtained from canteens in schools and factories, food service facilities, homes, restaurants, and a hospital. Lipid contents of the samples were spread over wide range (0.28-17.70%), and the main fatty acids in most samples were palmitic, stearic, oleic, and linoleic acids. The reflectance spectra of air-dried and milled compost samples were measured using a scanning monochromator. Second derivative spectra from 700 to 2500 nm and multiple regression analysis were used to develop calibration equations for lipid content. The main wavelength of the best calibration equations was 2310 nm, which was attributed to the absorption bands of the CH2 stretch-bend combination of fatty acids. The standard error of prediction (SEP) of the best calibration was 1.24% . Although the fatty acid composition of the hospital sample was very different from others, it did not cause large errors in the estimates. In conclusion, NIRS is thought to be a practical method for evaluating plant inhibition caused by garbage compost.
The effect of temperature on L-lactic acid fermentation from Fresh Cassava Root (FCR) by Streptococcus bovis was investigated in new mediums: tofu liquid waste (TLW), and TLW with 2wt% concentrated maguro waste (TLW+CMW2) and also with standard medium (trypto soya broth; TSB), comparing with standard media (glucose in TSB) . The experimental results showed that lactic acid fermentations from FCR in three mediums and glucose in TSB were optimum at 39°C. The values of fermentation properties were found to be increasing in order FCR in TSB, glucose in TSB, FCR in TLW+CMW2, and FCR in TLW. The Arrhenius relationships for productivity and specific growth rate were then established. The values of activation energy (Ea) and deactivation energy (Ed) for lactic acid fermentation from all media were found to increase in order from FCR in TLW, FCR in TLW+CMW2, glucose in TSB, and FCR in TSB. The relations for activation energies and deactivation energies were in reverse to those for fermentation properties.
Some biopolymer gelation process shows an inflection point (IP) in a growth curve of a rheological observable. In this note, a kinetic treatment is presented for such a second-order food reaction process dx/dt=K2 (1-x) 2 where a general observable o grows with reaction degree x through the power-law type mixing rule oν= (1-x) oνR+xoνP. For-1<ν<1, the observable-time curve could possess IP at o*= (1-ν) 1/ν (1+ν) -1/νoP and K2t*=2-1 (1+ν) ν-1 (1- (oR/oP) ν) -1 with the maximum growth rate do/dt|t*=22 (1-ν) (1/ν) -1 (1+ν) - (1/ν) -1ν (1- (oR/oP) ν) -1oPK2. These results show that oR dependence disappears in the product (1+K2t*) do/dt|t*. The whole o-t curve is linearized with the transformation (oνP-oνR) (oνP-oν) -1=1+K2t. The case of ν=0 is compensated with a logarithmic type (In o) mixing rule.
Three types of hydrocarbon (potato starch, glucose and cellulose) were carbonized by superheated steam treatment, and their carbonization characteristics and reaction kinetics were investigated. To minimize the influence of the rate of heat transfer into the materials, fine powdery samples were used. Carbonization temperatures ranged from 498 K (225°C) to 548 K (275°C) . Potato starch melted and swelled at around 225°C, and carbonization proceeded with foaming of the sample. Glucose melted and swelled within a few minutes after treatment, and carbonization proceeded in a foamy state. Cellulose was carbonized without melting, and a powdery charcoal product was obtained. The carbonization rates of the three samples obeyed a first order rate equation. The activation energies for carbonization, evaluated from the rate constants, were in the range 133-167 kJ/mol, which is almost the same as the activation energies for thermal decomposition of starch and cellulose under nitrogen gas.
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