• Membrane and Water Treatment
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• v.9 no.4
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• pp.285-292
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• 2018

In the following study, Artificial Neural Network (ANN) is used for prediction of permeate flux decline during oily wastewater treatment by hybrid powdered activated carbon-microfiltration (PAC-MF) process using mullite and mullite-alumina ceramic membranes. Permeate flux is predicted as a function of time and PAC concentration. To optimize the networks performance, different transfer functions and different initial weights and biases have been tested. Totally, more than 850,000 different networks are tested for both membranes. The results showed that 10:6 and 9:20 neural networks work best for mullite and mullite-alumina ceramic membranes in PAC-MF process, respectively. These networks provide low mean squared error and high linearity between target and predicted data (high $R^2$ value). Finally, the results present that ANN provide best results ($R^2$ value equal to 0.99999) for prediction of permeation flux decline during oily wastewater treatment in PAC-MF process by ceramic membranes.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.319-328
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• 1994

Aluminium and titanium precursors containing $\beta$-diketonate ligands were used for the synthesis of polymeric sols of alumina and titania by sol-gel methods. To prepare polymeric sols by solgel processing, we synthesized modified precursors having chelating organic ligands. With these precursors it was found to be possible to control both hydrolysis and polycondensation reaction rates which resulted in ultrafine particles few nms of average size. The optimum molar ratio of acid to alkoxide for alumina sol was 0.3-0.4 and that of water to alkoxide &as 1. On the other hand, the corresponding ratios for titania sol were found be 0.25-0.20 and 1 respectively. Dynamic light scattering measurements indicated that the average particle size in both sols was in the order of few nms. SEM photographs were taken to observe crack-free and smooth surfaces of coated membranes after sintering at $450^{\circ}C$. Alumina coated membrane on a slide glass had about 4-4.5$\mu \textrm{m}$, thickness and titania coated one had 2-2.5$\mu \textrm{m}$, thickness. And according to TEM photographs, the grain size of titania was smaller than 30nm and that of alumina was in the range of few $\AA$s to 2nms. An X-ray diffraction study revealed that alumina was $\gamma$ phase and titania was anatase crystal.

• Membrane Journal
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• v.18 no.2
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• pp.176-184
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• 2008

Nano-porous ceramic membranes was synthesized by the sol-gel method. Gas permeation of hydrogen and nitrogen was determined by single composition gas. Pore size $0.1{\mu}m$ and porosity 32% of flat type ${\alpha}-Al_2O_3$ substrate was manufactured. An intermediate ${\gamma}-Al_2O_3$ layer with pore size of 4 nm was formed by dip-coating. Polymeric silica sol was synthesized by acid catalyzed hydrolysis and condensation of tetra-ethyl-ortho-silicate. Supported membranes on alumina were prepared by dipping and calcining. He, $N_2$ permeation experiments with nanoporous sol-gel modified supported ceramic membranes were peformed to determine the gas transport characteristics. $He/N_2$ permselectivity around $100{\sim}160$ and helium permeation in the order of $10^{-7}mol/m^2{\cdot}s{\cdot}Pa$ were measured in the temperature range of $303{\sim}363K$.

• Membrane Journal
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• v.16 no.1
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• pp.31-38
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• 2006

The ceramic microfiltration system with periodic $N_2$-back-flushing was operated for treating paper wastewater discharged from a company making toilet papers by recycling milk or juice cartons. Two kinds of alumina membranes with 7 channels used here for recycling paper wastewater. The optimal filtration time interval for HC04 membrane with $0.4{\mu}m$ pore size was lower value of 4 min than 16 min for HC10 with $1.0{\mu}m$ pore size at fixed back-flushing time 40 sec, trans-membrane pressure $1.0kg_f/cm^2$ and back-flushing pressure $5.0kg_f/cm^2$. From the results of TMP effect at fixed filtration time interval and back-flushing time, the lower TMP was better on membrane fouling because high TMP could make easily membrane cake and fouling inside membrane structure. However, we could acquire the highest volume of total permeate at the highest TMP for the reason that TMP was driving force in our filtration system to treat paper wastewater. Then the permeate water of low turbidity was acquired in our microfiltration system using multi channels ceramic membranes, and the treated water could be reused in paper process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.384-389
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• 2015

In this paper, we fabricated ceramic body and sapphire wafer in order to develop a hydraulic pressure sensor with high sensitivity and high temperature stability. The sapphire wafer was adopted with a membrane of capacitance ceramic pressure sensor. The capacitance value of the sensor for the finite element analysis(FEM) showed a linear pressure characteristics. Membrane was processed with a diameter of 32.4 mm and a thickness of 1 mm by using alumina powders. Ceramic body was processed with a diameter 32.4 mm and a thickness 5 mm. The capacitance pressure sensor was made with high heat treatment of the ceramic body and the sapphire wafer. Initially capacitance of the pressure sensor was 50 pF and a capacitance of 110 pF was measured from 5 bar pressure. Output voltage of 5 V was appeared at 5 bar pressure.

• Membrane Journal
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• v.25 no.5
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• pp.422-430
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• 2015

The present study announces that the pH value of seed coating solution makes a significant effect on the microstructure of silicalite-1 zeolite layer formed on ${\alpha}$-alumina support. Seed with an average diameter of 75 nm was dispersed in ethanol to prepare three kinds of seed coating solutions with different pH values, and dip-coated on the support. The pH value was controlled to be 2.2, 7.0, and 9.3, respectively. In the secondary growth process, pH 7 seed solution resulted an uniform, 3 to $4{\mu}m$ thick, completely covered, and 100 nm grained silicalite-1 zeolite separation layer. The uniformity and completeness were explained by a uniform, closely packed, multi-layered, and completely covered seed coating in the pH 7 condition. In the condition, ${\alpha}$-alumina support and seed are oppositely charged: support is positively charged (8.4 mV) and seed, negatively (-1.7 mV). The opposite charging induced a strong electrostatic attraction between seed and support, which made the good seed coating state. On the other hand, pH 2.2 and pH 9.3 seed solutions resulted non-uniform, partially covered, and around $1{\mu}m$ grained zeolite separation layer, since seed and support are the same sign charged in the conditions. The same sign charging induced a strong electrostatic repulsion between seed and support which caused a low coverage of seed. It could be concluded that the pH value of seed coating solution is a key parameter to determine the microstructure of silicalite-1 zeolite separation layer.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.214-218
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• 2014

In this study, nanoporous $Cu_3(BTC)_2$ membranes were synthesized on macroporous alumina tube supports by solvothermal method. It is very difficult to prepare uniform and crack-free $Cu_3(BTC)_2$ layer on macroporous alumina support by in situ solvothermal method. In this study, continuous and crack-free $Cu_3(BTC)_2$ tubular membranes could be obtained by in situ solvothermal process after surface modification of alumina support. The surface modification was conducted by spraying Cu precursor solution on the alumina support heated at $200^{\circ}C$. The prepared $Cu_3(BTC)_2$ tubular membranes were characterized by XRD, FE-SEM and gas permeation experiments. $H_2$ permeance through $5{\mu}m$ thick $Cu_3(BTC)_2$ tubular membrane was calculated to be $7.8{\times}10^{-7}mol/s{\cdot}m^2{\cdot}Pa$ by single gas permeation test, with the ideal selectivities of $H_2/N_2=11.94$, and $H_2/CO_2=12.82$.

• Membrane Journal
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• v.22 no.2
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• pp.120-127
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• 2012

In this study, separation of ethylbenzene from mixed xylene was performed by using TS-1 zeolite membrane. TS-1 zeolite membranes were prepared by microwave synthesis and changing the reaction temperature. MFI-type TS-1 membranes are synthesized on alumina tubes by functional coating using 3-chloropropyltrimethoxysilane (3CP-TMS). On top surface of interlayer, nano TS-1 crystals were seeded. To form interlayer, microwave-assisted growth of TS-1 zeolite was carried out and thin zeolite layers were produced. All of the prepared membranes are tested to separate ethylbenzene from mixed xylene at different operating temperatures. TS-1 membrane with zeolite seed synthesized at $170^{\circ}C$ compared to 120, $140^{\circ}C$ shows the best ethylbenzene separation at the operation temperature of $200^{\circ}C$ from ternary mixed xylene containing certain composition of ethylbenzene/p-xylene/m-xylene. (separation factor : 2.64, ethylbenzene flux : 1703.0 mol/$m^2{\cdot}s{\cdot}Pa$).

• Membrane Journal
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• v.9 no.3
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• pp.178-184
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• 1999

A periodic backflushing was performed to reduce the membrane fouling of ultrafiltration for wastewater, and the effect and the optimum condition were investigated in this study. The alumina¬ceramic tubular membrane with pore size of 0.02${\mu}m$ was used for the wastewater treated by coagulation and sedimentation from two paper plants, of which A plant made toilet paper by recycling milk paper cartons and B plant recycled corrugated cardboards. And the effect of periodic backflushing to membrane fouling and quality of permeate were studied with a constant backflushing time of 3 sec. As results of measuring SS, TDS, and COD of source and permeate, the rejection rate of SS showed the highest value at the backflushing period of 15 see, which was the shortest time in these experiments, in case of waste¬water discharged from A plant. However, the rejection rate of COD had the highest value at the period of 30 sec for wastewater from both A and B plant. Then, the rejection rate of TDS was almost same at 30 and 60 sec for A plant wastewater, and the highest at 60 see for B plant. The effect of periodic back¬flushing to membrane fouling was investigated by change of permeate flux according to operating time. The permeate flux decreased slowly at the operation with backflushing, and was higher compared with that without backflushing in both case of A and B wastewater. But, the optimum period with the highest flux of A wastewater was different from that of B, because SS and COD of A was higher than those of Band TDS of B was higher than that of A.

• Membrane Journal
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• v.16 no.1
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• pp.25-30
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• 2006

The NaA zeolite membrane was synthesized on the surface of a porous ${\alpha}$-alumina support from the reaction solution composed of 1Si : 1Na : 4Na $6H_{2}O$. The pervaporation performance of the synthesized NaA zeolite membrane was investigated for the iso-propyl alcohol (IPA) aqueous solution according to the different feed concentration and the different operating temperature. The total flux decreases by increasing the feed IPA concentration and increases by increasing the temperature. The total flux was about $4.0{\times}10^3g/m^2\;hr\;at\;60^{\circ}C$ and 0.6 mole fraction of IPA and the separation factor was $1.8{\times}10^7\;at\;60^{\circ}C$ and 0.8 mole fraction of IPA. The separation performance of water through the NaA membrane was found to be superior to that obtainable with a distillation process just by comparison of the vapor-liquid equilibrium data.