• Membrane and Water Treatment
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• v.15 no.2
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• pp.89-98
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• 2024

The ability of Zizyphus lotus stem powder (ZLSP) to remove Pb (II) and Cd (II) ions from an aqueous solution was evaluated. The present phenomenon of biosorption was revealed to depend on pH, biosorbent dosage, temperature, initial ionic concentration, time of contact and biosorbent's particle size. The sorption process was exothermic (∆H°<0), and showing a strong Pb(II)/Cd(II)-ZLSP affinity (∆S°>0). Gibbs free energy data (∆G°<0, and decreases as temperature increase) reveals that the process studied is characterized by its feasibility and spontaneous nature. The best fits of the equilibrium data were obtained by the Temkin model and the Langmuir model. The maximum Pb(II)/Cd(II)-ZLSP biosorption capacities were 33.02 mg/g for Pb (II) and 20.73 mg/g for Cd (II). The pseudo-second order model was the most appropriate for fitting the kinetic data. The characterization of the biochemical groups essentially involved in the sorption phenomenon was made possible by FTIR spectral analysis. The capacity of ZLSP as an effective and ecofriendly biosorbent is confirmed through this study.

• Clean Technology
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• v.7 no.1
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• pp.75-80
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• 2001

In this study, hexavalent chromium (Cr(VI)) plating wastewater in strong acidic condition was treated by reduction and alkalization. Ferrous sulfate ($FeSO_4$), known to reduce Cr(VI) to Cr(III) rapidly at acidic pH, was used as a reductant of Cr(VI). The optimum reduction condition of Cr(VI) was observed at iron to chromium dose ratio of 3:1 by mole concentration. The precipitation of Cr(III) as $Cr(OH)_3$, was achieved by the pH adjustment in the limestone aeration bed. The precipitates were removed less than the upper limit of chromium for effluent at pH over 5.0. The continuous removal of Cr(VI) was performed using the process consisting of reduction vessel, limestone aeration bed, and sedimentation tank coupled with metal screen membrane. As pH was maintained around 5.0 in the limestone aeration bed, insoluble chromic hydroxide flocs was formed continuously. Most chromic hydroxide flocs were filtered by the metal screen membrane with 1450 mesh size, and the treated water to meet the upper limits of chromium for effluent (Cr Conc. 0.25~0.90 mg/l) was obtained in 30 minutes. Periodic backwashing decreased the fouling on the membrane rapidly.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.3
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• pp.193-198
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• 2013

In general, boron recovery of 40-90% could be achieved by Reverse Osmosis (RO) membranes in neutral pH condition. As an emerging technology, Forward Osmosis (FO) membrane has attracted growing interest in wastewater treatment and desalination. The objective of this study is to evaluate the possibility of the boron removal in radioactive liquid waste by FO. In this study, the performance of FO was investigated to remove boron in the simulated liquid waste as the factors such as pH, osmotic pressure, ionic strength of solution, etc. The pH of feed solution is a major operating parameter which strongly influences to the permeation of boron and more than 80% of boron content can be separated when conducted at pH values less than 7. The water flux is not influenced but the boron flux and permeation rate tends to decrease in the low salt concentration of 1,000 mg/L. The boron flux increases linearly, but the permeation ratio of reducing boron is nearly constant even with changes in the draw solution concentration.

• Journal of Pharmaceutical Investigation
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• v.39 no.2
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• pp.97-106
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• 2009

Although lovastatin (LS) is widely used in the treatment of hypercholesterolemia, its bioavailability is known to be around 5%. This study was aimed to increase the solubility and dissolution-permeation rates of LS using solid dispersions (SDs) with bile salts. The solubilities of LS in water, aqueous bile salt solutions and non-aqueous vehicles were determined, and effects of bile salts on the cellulose or duodenal permeation of LS from SDs were evaluated using a horizontal permeation system. SDs were prepared at various ratios of LS to carriers, such as sodium deoxycholate (SDC), sodium glycocholate (SGC) and/or 2-hydroxypropyl-$\beta$-cyclodextrin (HPCD). The addition of bile salts (25 mM) in water increased markedly the solubility of LS by the micellar solubilization. Some non-aqueous vehicles were effective in solubilizing LS. From differential scanning calorimetric studies, it was found that the crystallinity of LS in SDs disappeared, indicating a formation of amorphous state. The SDs showed markedly enhanced dissolution compared with those of their physical mixtures (PMs) and drug alone. In the dissolution-permeation studies using a cellulose membrane, the donor and receptor solutions were maintained as a sink condition using pH 7.0 phosphate buffer containing 0.05% sodium lauryl sulfate (SLS). The flux of LS alone was nearly same as that of LS-SDC-HPCD (1:3:6) PM. However, the flux of LS-SDC-HPCD (1:3:6) SD slightly increased compared with drug alone and PM, suggesting that entrapment of LS in micelles does not significantly hinder the permeation across cellulose membrane. In the dissolution-duodenal permeation studies using a LS-HPCD-SDC (1:3:6) SD, the addition of various bile salts in donor solutions (25 mM) enhanced the permeation of LS markedly, and the fluxes were found to be $0.69{\pm}0.41$, $0.87{\pm}0.51$, $0.84{\pm}0.46$, $0.47{\pm}0.17$ and $0.68{\pm}0.32{\mu}g/cm^2/hr$ for sodium cholate (SC), SDC, SGC, sodium taurodeoxycholate (STDC) and sodium taurocholate (STC), respectively. The stepwise increase of donor SGC concentration increased the flux dose-dependently. From the relationship of donor SGC concentration and flux, the concentration of SGC initiating the permeation across the duodenal mucosa was calculated to be 11.1 mM, which is nearly same as the critical micelle concentration (CMC, 11.6 mM) of SGC. However, with no addition of bile salts and below CMC, the permeation was very limited and irratic, indicating that LS itself is very poor permeable. Higher protions of bile salt in SD such as LS-SDC or LS-SGC (1 : 49 and 1 : 69) showed highly promoted fluxes. In conclusion, SD systems with bile salts, which may form their micelles in intestinal fluids, might be a promising means for providing enhanced dissolution and intestinal permeation of practically insoluble and non-absorbable LS.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.439-446
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• 2009

This study was performed to evaluate SND(simultaneous nitrification and denitrification)efficiency, nitrogen removal efficiency and filtration function of non-woven fabric by using submerging MBR packed with granular sulfur covered with non-woven fabric filter. Synthetic wastewater was used as influent wastewater. Concentration of $NH_4{^+}-N$ in influent was maintained about 40 mg/L and the experiment was performed in four phases according to the flow rate. Nitrogen loading rate divided four phases ranging from $0.04 kg\;NH_4{^+}-N/m^3-day$ to $0.16 kg\;NH_4{^+}-N/m^3-day$. As a result, the maximum $NH_4{^+}-N$ removal rate was accomplished at $0.142 kg\;NH_4{^+}-N/m^3-day$ in nitrogen loading of $0.147 kg\;NH_4{^+}-N/m^3-day$. Nitrification efficiency was higher than 95% in all phases. $NO_3{^-}-N$ loading rate was adjusted ranging from $0.22 kg\;NO_3{^-}-N/m^3-day$ to $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal rate was accomplished up to $0.71 kg\;NO_3{^-}-N/m^3-day$ in $NO_3{^-}-N$ loading of $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal efficiency was 95% in $NO_3{^-}-N$ loading of $0.22 kg\;NO_3{^-}-N/m^3-day$. T-N removal rate was 90% and concentration of T-N in effluent was 3.7 mg/L in T-N loading rate of $0.039 kg\;NO_3{^-}-N/m^3-day$. In this study, TMP in reactor with and without non-woven fabric filter were observed to define fouling of hollow-fiber membrane module. Reaching time to standard washing pressure(22 cm Hg) of two reactors were 29 days with non-woven fabric But the reactor without non-woven fabric reached standard washing pressure only after 4 days. Accordingly, non-woven fabric was demonstrated the superiority as a filtration ability. With high nitrogen removal rate and decreasing of fouling of membrane, MBR packed with granular sulfur covered with non-woven fabric filter submerging in activated sludge aeration tank can be used as an advanced treatment process.

• Membrane Journal
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• v.8 no.2
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• pp.77-85
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• 1998

To treat effectively EDIR (electrodeposition ion removal) wastewater in terms of CO$_{Mn}$ 1,500~2,000 ppm generated from aluminum painting process, a RO (reverse osmosis) process was designed and installed to recover and reuse the concentrated solvent sent back to the electrocodeposition tank while the permeate reused as rinse water. A RO system in which three polyamide-spiral wound modules ($102\Phi \times 1,016L$ mm) connnected in series had been running to treat 20 m$^3$ in waste volume in 3 days batch operation at the condition of system recovery of 30 %, applied pressure 11.5 $kg_f/cm^2$ and room temperature. During 42 hours continuous operation leading to 5-fold decrease in waste volume, nearly constant permeation flux of 390 l/m$^2$-hr was maintained and the permeate with average CO$_{Mn}$, 300 ppm was obtained which could be used for washing the remaining paint solution in ion-exchange tower instead of demineralized water. Also COD$_{Mn}$ rejection as a function of running time was observed to be in the range of 78~87 % and the observed solvent rejections for ethyl cellusolve, buthyl cellusolve and n-butanol were 79 %, 87 % and 70 %, respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.31-39
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• 2005

Direct methanol fuel cell (DMFC) is considered as a candidate for portable power sources, that could overcome the disadvantages of lithium battery. But in order to attain commercial viability the long term stability of the DMFC should be achieved. Understanding the long-term behavior of membrane-electrode assembly (MEA) is a prerequisite to this purpose and the optimization of the MEA is also needed. In this study we have investigated the changes in performance and electrochemical properties of the MEA during extended operation and the effects of heat treatment of MEA on the long-term performance. The MEAs have been treated in an autoclave with saturated water vapor at 120$^{\circ}C$, vacuum oven at 140$^{\circ}C$ and boiling in organic solvents. The autoclaved MEA was found to be have the best long term performance. The on-off operation mode also increased the performance probably due to effective removal of products from the electrodes. Physical and electrochemical analyses using a scanning electron microscope, impedance analyser and half-cell technique have been done to characterize the MEAs.

• Korean Journal of Community Nutrition
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• v.4 no.2
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• pp.239-247
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• 1999

Six-week-old Sprague Dawley rats were fed the diets of 20% casein or soy protein. Two weeks after the feeding, hepatocellular chemical carcinogenesis was initiated by diethylnitrosamine(DEN), and promoted by the diet containing 0.01% 2-acetylamino-fluorene(AAF) and two-thirds partial hepatectomy(PH). The animals were sacrificed at 8 weeks after the DEN injection. The area of placetal glutathione S-trnasferase(GST-P) positive foci, the activities of several enzymes in cellualr antioxidant enzyme systems and glucose 6-phosphatase were determined to investigate the mechanism of the anticarcinogenic effect by the dietary proteins. In another set of experiments, the drinking water of rats fed casein was supplemented with 1.5% inositol hexaphosphate(InsP6) to elucidate whether it has the comparable anticancer action of soy protein. The area and number of GST-P positive foci in the soy protein group were significantly(p<0.05) lower than those inthe casein group. The livers of rats fed casein showed moderate fattydegeneration and larger hyperplastic nodules than those of rats fed soy protein. In another set of experiments, the area and number of GST-P positive foci in the rats fed casein supplemented with InsP6 were not significantly different from those in the rats fed casein or soy protein. The lipid peroxidation of rats fed different protein sources showed no significant difference. Glutathione S-transferase(GST) activities were increased significantly(p<0.05) by carcinogen treatment in all dietary groups. Glucose 6-phosphatase(G6Pase) activities were decreased by carcinogen treatment, and hence showed a reverse relationship(r=-0.695, p<0.01) to the GST-P positive foci. Therefore, the activities in the rats fed casein were lower than those in the rats fed soy protein. These results suggest that the soy protein seems to be more anti-carcinogenic than casein by decreasing the preneoplastic lesion and by increasing the membrane stability but inositol hexaphosphate, a component of soy protein, may not be protective against hepatocarcinogenesis.

• Journal of Environmental Science International
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• v.6 no.2
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• pp.125-131
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• 1997

The mechanism of stomatal closing in response to $O_2$ was indirectly investigated by using $H_2O_2$ which is the intermediate product of $O_2$ metabolites. Stomata in epidermal strips close in response to $H_2O_2$. The effect of $H_2O_2$ on stomatal closing was dependent on the concentration of $H_2O_2$. 10 ppm $H_2O_2$ showed a clear effect on stomatal closing and 1000 ppm $H_2O_2$ induced complete stomatal closing after the treatment of 3 hours. Stomatal closing by $H_2O_2$ in intact leaf was also observed by measuring the diffusion resistance with porometer. It was found that the stomatal closing by $H_2O_2$ was not mediated by $Ca^{2+}$, and that was a different result observed in stomatal closing by water stress. Reversely, $Ca^{2+}$ showed a great inhibition on stomatal closing. The leakage of K+ in epidermal strips was doubled in response to $H_2O_2$ when it was campared to the control. 10 ppm $H_2O_2$ decreased photosynthetic activity. Fv/Fm representing the activity of Photosystem II was reduced about 4 % in 10 ppm $H_2O_2$ and 8 % in 100 ppm $H_2O_2$ In the treatment of 1.5 hour. However, stomatal closing by 10 ppm $H_2O_2$ was reduced about 56 %. According1y, it can be suggested that stomatal closing by $H_2O_2$ is related with the decrease of photosynthetic activity, but it was chiefly induced by the change of the membrane permeability. Key words Commelina communis, stomatal closing, $H_2O_2$, $Ca^{2+}$, photosynthesis.

• Membrane and Water Treatment
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• v.11 no.4
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• pp.283-294
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• 2020

This work aims at studying the feasibility of continuous removal of mixed heavy metal ions from simulated zinc plating wastewaters by coupling a microbial fuel cell and a microbial electrolysis cell in batch and continuous modes. The discharging voltage of MFC increased initially from 0.4621 ± 0.0005 V to 0.4864 ± 0.0006 V as the initial concentration of Cr⁶⁺ increased from 10 ppm to 60 ppm. Almost complete removal of Cr⁶⁺ and low removal of Cu²⁺ occurred in MFC of the MFC-MEC-coupled system after 8 hours under the batch mode; removal efficiencies (REs) of Cr⁶⁺ and Cu²⁺ were 99.76% and 30.49%. After the same reaction time, REs of nickel and zinc ions were 55.15% and 76.21% in its MEC. Cu²⁺, Ni²⁺, and Zn²⁺ removal efficiencies of 54.98%, 30.63%, 55.04%, and 75.35% were achieved in the effluent within optimum HRT of 2 hours under the continuous mode. The incomplete removal of Cu²⁺, Ni²⁺ and Zn²⁺ ions in the effluent was due to the fact that the Cr⁶⁺ was almost completely consumed at the end of MFC reaction. After HRT of 12 hours, at the different sampling locations, Cr⁶⁺ and Cu²⁺ removal efficiencies in the cathodic chamber of MFC were 89.95% and 34.69%, respectively. 94.58%, 33.95%, 56.57%, and 75.76% were achieved for Cr⁶⁺, Cu²⁺, Ni²⁺ and Zn²⁺ in the cathodic chamber of MEC. It can be concluded that those metal ions can be removed completely by repeatedly passing high concentration of Cr⁶⁺ through the cathode chamber of MFC of the MFC-MEC-coupled system.