• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.473-477
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• 2022

In this study, candidate technologies for lithium recovery from the process waste liquid generated in the waste battery recycling process were reviewed, and technologies applicable to the process from the commercialization point of view were reviewed from a qualitative point of view. The evaporation method is difficult to apply because it requires a large-scale land and shows a low recovery rate due to the loss of Li during the concentration process. In the case of precipitation, a commercially available technology shows a high recovery rate due to the high Li/Na selectivity of phosphoric acid, but there are disadvantages in that the process is complicated due to the use of expensive phosphoric acid, requiring a recovery step, and continuous operation is impossible because solids are handled in the Li concentration process. In the case of solvent extraction, if we find an inexpensive extractant with high Li/Na selectivity, continuous operation is possible with the method used in extraction of other metals in the previous step, and when Li is concentrated, continuous operation is possible because it is in a liquid state. If it shows a similar recovery rate compared to precipitation technology, commercialization will be the most likely.

• Ecology and Resilient Infrastructure
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• v.8 no.4
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• pp.281-289
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• 2021

Commercially used disposable cups undergo fragmentation in the environment and become microplastics (MPs). These MPs can be ingested by aquatic organisms and cause a range of adverse effects. We assessed the acute and chronic toxicity of disposable cup-derived MP fragments in Daphnia magna. MP fragments were identified as a polyethylene terephthalate (PET) fragment with a size of 33.18 ± 7.76 ㎛. The presence of three additives including 1- Propanone. 1-phenyl-3-[2-(phenylmethoxy)phenyl]-, p-Xylene and ethylbenzene was analyzed from MP fragments. The 48 h acute toxicity revealed that 20 % of immobilization and mortality were found at the highest concentration of PET MP (200 mg L^-1). The 21 d chronic toxicity revealed that PET MP fragments significantly (p < 0.05) more reduced survival rate (31 %), total offspring (52 %) in D. magna compared with control group. The developmental abnormality of offspring (3.5%) by PET MP fragments was significantly (p < 0.05) higher than control groups (0.3%). These results are possibly induced by gut blocking by ingestion of MP fragments and their longer retention time. These findings indicate that the fragmentation of disposable cups (PET polymers) into small-sized MP fragments pose a significant ecological risk to aquatic organisms. Further studies are required to elucidate the underlying toxicity mechanisms.

• Journal of Korean Society of Forest Science
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• v.100 no.1
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• pp.14-24
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• 2011

Anticancer activity of Acer mono aqueous extracts was enhanced by nano-encapsulation process of gelatin. The cytotoxicity on human normal lung cell (HEL299) of the extracts from WE (water extract at 100) showed 23.51%, lower than that from NE (nano-encapsulatioin of water extract of Acer mono) in adding the maximum concentration of 1.0 mg/mL. NE showed more potent scavenging effect as 73.15% than the WE. On SOD-like test, the NE showed highest activity as 32.33% at 1.0 mg/mL concentration. Human stomach adenocarcinoma, liver adenocarcinoma, breast adenocarcinoma and lung adenocarcinoma cell growth were inhibited up to about 59-73%, in adding 1.0 mg/mL of NE. NE was 15% higher than conventional water extraction. Among several cancer cell lines (stomach adenocarcinoma, liver adenocarcinoma), the growth of digestive related cancer cells were most effectively inhibited as about 71-73%. The size of nano particles was in the ranges of 100-200 nm, which can effectively the penetrate into the cells, it was observed by real time confocal microscope. It tells that the aqueous extracts of Acer mono bark could be definitely enhanced by nano-encapsulation process.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.272-278
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• 2013

The hybrid system composed of a photocatalytic reactor and a biofilter was operated under various operating conditions in order to treat malodorous waste air containing ammonia which is a major air pollutant emitted from composting factories and many publicly owned treatment works. Total ammonia removal efficiency of the hybrid system was maintained to be ca. 80% even though its inlet loads were increased at a higher operating stage according to an operating schedule of the hybrid system. The ammonia removal efficiency of photocatalytic reactor was decreased from 65% to 22% as ammonia inlet loads to photocatalytic reactor were increased. In spite of same inlet loads of ammonia to the photocatalytic reactor, the ammonia removal efficiency of photocatalytic reactor with lower ammonia concentration of fed-waste air was higher than that with higher ammonia concentration of fed-waste air. To the contrary, during the first half of the hybrid system operation the ammonia removal efficiency of a biofilter was quite suppressed while, despite of increased ammonia inlet loads, the ammonia removal efficiency of the biofilter was continuously increased to 78% and reached the ammonia removal efficiency similar to what Lee et al. attained. The maximum ammonia elimination capacity of the photocatalytic reactor was observed to be ca. 16 g-N/$m^3$/h. In an incipient stage of hybrid system run, the ammonia elimination capacity of the biofilter showed little sensitivity against ammonia inlet loads to the hybrid system. However, in the 2nd half of its run, the ammonia elimination capacity of the biofilter was increased abruptly in case of high ammonia inlet loads to the hybrid system. In 6th stage of hybrid system run, total ammonia inlet load attained at ca. 80 g-N/$m^3$/h corresponding to 16 g-N/$m^3$/h of ammonia elimination capacity of the photocatalytic reactor. Then, the remaining ammonia inlet load to the 2nd and main process of the biofilter and its elimination capacity was expected and shown to be ca 64 g-N/$m^3$/h and ca 48 g-N/$m^3$/h, respectively. The ammonia elimination capacity of the biofilter was close to 1,200 g-N/$m^3$/day of the maximum elimination capacity of the investigation performed by Kim et al.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.514-520
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• 2014

In this study, the production potential of alternative coagulant ($Al_2(SO_4)_3$ solution) having the identical coagulation activity with respect to the commercial coagulant was investigated. The raw material of alternative coagulant was a spent catalyst including aluminium (waste activated alumina) generated in the manufacturing process of the polymer. The alternative coagulant was produced through a series of processes: 1) intense heat and grinding, 2) chemical polymerization and substitution with $H_2SO_4$ solution, 3) dissolution and dilution and 4) settling and separation. To determine the optimal operating conditions in the lab-scale autoclave and dissolver, the content of $Al_2O_3$ in alternative coagulant was analyzed according to changes of the purity of sulfuric acid, reaction temperature, injection ratio of sulfuric acid and water in the dissolver. The results showed that the alternative coagulant having the $Al_2O_3$ content of 7~8% was produced under the optimal conditions such as $H_2SO_4$ purity of 50%, reaction temperature of $120^{\circ}C$, injection ratio of $H_2SO_4$ of 5 times and injection ratio of water of 2.3 times in dissolver. In order to evaluate the coagulation activity of the alternative coagulant, the Jar-test was conducted to the effluent in aerobic reactor. As a result, in both cases of Al/P mole of 1.5 and 2.0, the coagulation activity of the alternative coagulant was higher than that of the existing commercial coagulant. When the production costs were compared between the alternative and commercial coagulant through economic analysis, the production cost reduction of about 50% was available in the case of the alternative coagulant. In addition, it was identified that the alternative coagulant could be applied at field wastewater treatment plant without environmental problem through ecological toxicity testing.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.768-774
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• 2009

To improve the productivity of 1,3-propanediol(1,3-PD) with K. pneumoniae DSM4799 using pure glycerol and crude glycerol derived from the biodiesel process, optimizing fermentation conditions was performed by changing environmental factors such as anaerobic/aerobic condition, temperature, glycerol concentration, and pH. When anaerobic conditions were maintained, there was an improved 1,3-PD production compared with that from aerobic/anaerobic 2-stage fermentation. From the results with temperature $26{\sim}37^{\circ}C$, the higher 1,3-PD production yield was observed at $30{\sim}33^{\circ}C$. For an initial glycerol concentration higher than 60 g/L, cell growth and 1,3-PD production were inhibited. When crude glycerol was used, the initial 1,3-PD production appeared to be inhibited. After 48 hr of incubation, however, 1,3-PD production with crude glycerol was even higher than that with pure glycerol, demonstrating the feasibility of 1,3-PD production using crude glycerol as a substrate. Fed-batch fermentation was applied for the high concentration of 1,3-PD without substrate inhibition. By regulating pH at 7 during the fed-batch with glycerol lower than 40 g/L, the yield of 1,3-PD was 25% higher than that without pH regulation(0.56 g/g vs. 0.45 g/g). In conclusion, based on our results, anaerobic conditions, temperature at $30^{\circ}C$, pure or crude glycerol lower than 40 g/L, and pH regulation at 7 were the optimized conditions for 1,3-PD production using K. pneumoniae DSM4799, making it more feasible to produce 1,3-PD at higher concentration and a lower price.

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.80-86
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• 2013

In this study, the photocatalytic reactor system equipped with photocatalyst-carrying-silica-media cartridges [photocatalytic reactor system (1)] was used to perform the treatment of waste air containing malodor and volatile organic compound (VOC). The result of its performance was evaluated and compared with that of the photocatalytic reactor system equipped with commercial photocatalyst-carrying-nonwoven filter-media cartridges [photocatalytic reactor system (2)]. In case of photocatalytic reactor system (1), at the 1st stage of run the removal efficiencies of ethanol and toluene continued to be 80% and 20%, respectively. However, unlike toluene, the removal efficiency of ethanol dropped to 40% at the end of the 1st stage of run. The removal efficiency of hydrogen sulfide decreased from 100% to 90%. At the 2nd stage of its run the removal efficiency of ethanol decreased to 10% while the removal efficiencies of hydrogen sulfide and toluene remained as same as 90% and 20%, respectively, even though the inlet load of toluene increased by factor of four. In the 3rd stage of its run, as the result of application of aluminium-coated reflector film to the inner wall of photocatalytic reactor system, the removal efficiencies of ethanol and toluene increased by 5% to be 15% and 25%, respectively. In case of photocatalytic reactor system (2), at the 1st stage of its run, the removal efficiencies of ethanol, hydrogen sulfide and toluene continued to be 10%, 97% and 100%, respectively. However, at 2nd stage of its run their removal efficiencies became 5%, 95% and 2~3%, respectively, which showed that the removal efficiencies of ethanol and hydrogen sulfide decreased insignificantly while the removal efficiency of toluene dropped significantly from the perfect elimination. Moreover, the reflector film did not affect the performance of photocatalytic reactor system (2) at all. Therefore the removal of ethanol, hydrogen sulfide and toluene by photocatalytic reactor system (2) was mainly attributed to hydrophobic adsorption of its nonwoven filter media and its extent of photocatalytic removal turned out to be negligible, compared to that of photocatalytic reactor system (1).

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.47-53
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• 2011

$SF_6$ (Sulfur hexafluoride) possesses high GWP (Global Warming Potential) as sepcified by the IPCC (Intergonvernmental Panel of Climate Change). Recently, the recovery-separtion of $SF_6$ research area, including permeation properties studies using various membrane's materials and the practical operation of recovery-separtion using membrane of waste $SF_6$ gas is in the initial state. The separation efficiency of a single $SF_6$ and waste $SF_6$ mixture was evaluated using a PSF (polysulfone), PC (tetra-bromo polycarbonate) and PI (polyimide) hollow fiber membranes. According to the results of single gases permeation properties, PI membrane has the highest permselectivity of $N_2$ gas in $N_2/SF_6$ gas. Under the condition of P=0.5 MPa, the highest concentration of recovered $SF_6$ is 95.6 vol % in the separation experiment of $SF_6/N_2$ mixture gas by PC membrane. Under the operation pressure of P=0.3 MPa at a fixed retentate flow rate fixed of 150 cc/min, the maximum recovery efficiency of $SF_6$ is up to 97.8% by PSF membrane. From the results above, it is thought that the separation and recovery technique of $SF_6$ gas using membrane will be used as the representative eco-technology in the $SF_6$ gas treatment in the future.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.874-882
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• 2019

In this study, the gasification characteristics of four types of unused woody biomass and one waste wood in a lab-scale bubbling fluidized bed gasifier (Diameter: 0.11 m, Height: 0.42 m) were investigated. Effect of equivalence ratio (ER) of 0.15-0.3 and gas velocity of $2.5-5U_0/U_{mf}$ are determined at the constant temperature of $800^{\circ}C$ and fuel feeding rate of 1 kg/h. The silica sand particle having an average particle size of $287{\mu}m$ and olivine with an average particle size of $500{\mu}m$ were used as the bed material, respectively. The average product gas composition of samples is as follows; $H_2$ 3-4 vol.%, CO 15-16 vol.%, $CH_4$ 4 vol.% and $CO_2$ 18-19 vol.% with a lower heating value (LHV) of $1193-1301kcal/Nm^3$ and higher heating value (HHV) of $1262-1377kcal/Nm^3$. In addition, it was found that olivine reduced most of C2 components and increased $H_2$ content compared to silica sand, resulting in cracking reaction of tar. The non-condensable tar decreases by 72% ($1.24{\rightarrow}0.35g/Nm^3$) and the condensable tar decreases by 27% ($4.4{\rightarrow}3.2g/Nm^3$).

• Food Science and Preservation
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• v.31 no.4
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• pp.673-681
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• 2024

This study was conducted to develop kombucha with better functionality. The developed kombucha (CK) was prepared using the sugar extracts from fruits of Cudrania tricuspidata (Carrière) Bureau ex Lavallée instead of the sugar, which is used as a substrate for SCOBY in conventional kombucha (K). During fermentation, the soluble solids content significantly decreased in CK compared to K, and the pH change decreased rapidly in CK compared to K. On the 14^th day of fermentation, the weight of the SCOBY in CK was higher than that in K. Immediately after preparation, K contained only sucrose, but CK contained sucrose, glucose, and fructose. SCOBY appears to use glucose and fructose preferentially during fermentation. K contained acetic acid and citric acid right after preparation. However, as fermentation progressed, the composition changed to acetic acid, citric acid, and lactic acid. At the same time, CK initially consisted of citric acid, lactic acid, and acetic acid. However, acetic acid and citric acid increased but lactic acid decreased significantly on the 14^th day of fermentation. In the cytotoxicity studies, the CK showed a proliferation-promoting effect on normal lung cells (MRC-5) and strong cytotoxicity against human lung cancer cells (A549). These results suggest that the kombucha made from sugar extracts of C. tricuspidata fruits can be used as a more functional beverage than regular kombucha.