• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.3
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• pp.89-96
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• 2005

In the present work, production of organophosphorus hydrolase (OPH) that is secreted in periplasmic space of recombinant Escherichia coli was performed for degradation of environmental toxic organophosphate compounds, paraoxon. The optimal conditions for enhancement of OPH production were 1.0 mM isopropyl-${\beta}$-D-thiogalactopytanoside (IPTG), 0.25 mM $Co^{2+}$, and 0.1 mM ethylenediamine tetraacetate (EDTA). Under these culture conditions, the maximum OPH production was $174Unit/L{\cdot}OD$. In addition, 1 mM of paraoxon was completely degraded by OPH. These results can be used as a bioremediation tool for removal of environmental toxic organophosphate compounds remaining in soil and aquatic environment.

• Resources Recycling
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• v.27 no.1
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• pp.106-117
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• 2018

The present study was carried out to find a suitable drying method for the determination of non-evaporable water in hydraulic inorganic materials. In Part 1 of the paper, the case ordinary Portland cement was discussed and, in this Part 2, the case of alkali active slag (AAS) was investigated. Various drying methods including vacuum and oven drying, and an ignition, were used for the AAS system having different w/b, types and amounts of alkali activators. It was found that a combination of the vacuum and oven drying was a suitable drying method for the AAS case. Although a part of the crystallized water in hydration products was decomposed, but the free and adsorbed water could be completely evaporated and the deviation of the results was small.

• Resources Recycling
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• v.18 no.4
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• pp.38-43
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• 2009

The synthesis of aluminum oxalate, one of the aluminum organic compounds, has been performed using aluminum hydroxide as a raw material. For this aim, domestic aluminum hydroxide of 99.7% purity was dissolved by oxalic acid to produce an aqueous aluminum solution. As a result, it was found that aluminum hydroxide could be dissolved almost completely by the reaction with 1.0 mole/l oxalic acid solution at $90^{\circ}C$ for 16 hr. It was strongly required to keep the ratio of ethanol/Al solution more than 2.0 for the synthesis of aluminum oxalate from the aluminum solution. Furthermore, the pH should be controlled to be more than 8.2 in order to obtain the recovery of aluminum oxalate higher than 90%. From the chemical analysis of aluminum oxalate prepared in this work, the content of $NH_4$, Al and C was found to be 14.5, 7.18 and 17.4%, respectively. Accordingly, the aluminum oxalate synthesized from the aluminum solution was confirmed to be $(NH_4)_3Al(C_2O_4)_3$ $3H_2O$.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.4
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• pp.128-135
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• 2005

This study was done to improve the effectiveness of nitrification and denitrification using the aeration-anoxic combination method using CFSTR(continuous-flow stirred-tank reactor) attached with an anoxic reactor filled with a media. In order to calculate the concentration of nitric acid within the aeration tank proportional to the anoxic rate within the reactor, supernatant within the inflow and precipitation tanks were influxed into the anoxic reactor. The rate of nitrogen removal was calculated using the concentration of inflow and flow of returned supernatant. From the results of this experiment, the carbon source needed in the anoxic reactor came from the inflow so that anoxification was achieved completely using the inflow source without the introduction of an external carbon source. However, as the ratio of nitric acid becomes large in inflow and nitric acid flow, the carbon source within the input source decreases so that the concentration of carbon source is important.

• Resources Recycling
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• v.16 no.5
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• pp.65-70
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• 2007

This study presents the findings of the experiments that were conducted on single- and multi-stage solvent extractors using the stimulus-response method, with the am of identifying flow characteristics of the material inside the mixer-settler-type extractor. The results of this study show that the response characteristics of a single-stage mixer is the same as that of a completely stirred tank reactor (CSTR), and that the lag time of a mixer-settler-type extractor increases with the number of its extraction stages. The experimental data for the single- and multiple-stage extractors were analyzed using K-RTD, a response analysis program, to obtain a retention time distribution (RTD) model of one-stage and four-stage extractors. The correlation coefficient between the calculated values and the experimental data was 0.963 for the one-stage extractor and 0.995 for the four-stage extractor, showing quite a good correlation.

• Resources Recycling
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• v.9 no.4
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• pp.3-15
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• 2000

Reduction of Electric Arc Furnace dust with carbon (graphite) was studied at the temperature range of $800^{\circ}C$ to $1100^{\circ}C$ in Ar gas atmosphere. The briquetted dust with graphite powder was heated in a vertical tube furnace for given reaction time and Quenched in Ar gas atmosphere. It was found that initially the reduction of Zn was chemically controlled and the activation energy was about 120 KJ/mole. Because the almost all of Pb was removed with Cl in the form of $PbCl_2$, it is considered that Pb is removed by chloride reduction. Cu was vaporized as a chloride up to 30% of its original content, but the remaining of Cu would be accumulated with the reduced iron. and also, Cd was removed completely within 15 min. at $1000^{\circ}C$.

• Resources Recycling
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• v.22 no.6
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• pp.48-54
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• 2013

The methods to separate and remove copper in the mixed solution ((399 ppm Cu, 208 ppm Fe, 15.3 g/L Ni, 2.1 g/L Co) with nickel, cobalt and iron were investigated. With hydroxide precipitation method, copper and iron ions were completely precipitated and removed from the solution at pH 7 while some nickel and cobalt also were precipitated. 99.75% copper could be precipitated and removed as copper sulfide from the solution with adding $Na_2S$ (1.25 w/v concentration) of 2 times equivalent of Cu at pH 1. Copper was selectively absorbed on TP 207 ion exchange resin at equilibrium pH 2.0 and could be eluted from copper-loaded resin using 5% $H_2SO_4$.

• Resources Recycling
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• v.30 no.2
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• pp.53-60
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• 2021

Leaching experiments from single metal and metallic mixtures were conducted to develop a process for the recovery of cobalt, copper, and nickel in spent lithium ion batteries. Inorganic and organic acid solutions without oxidizing agents were employed. No copper was dissolved in the absence of an oxidizing agent in the leaching solutions. The leaching condition to completely dissolve single metal of cobalt and nickel was determined based on acid concentration, reaction temperature and time, and pulp density. The leaching condition to dissolve all of cobalt and nickel from the metallic mixtures was also obtained. Leaching of the metallic mixture with methanesulfonic acid led to selective dissolution of cobalt at low temperatures.

• Resources Recycling
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• v.31 no.1
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• pp.21-28
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• 2022

The smelting reduction of spent lithium-ion batteries results in metallic alloys of cobalt, nickel, and copper. To develop a process to separate the metallic alloys, leaching of the metallic mixtures of these three metals with H₂SO₄ solution containing 3% H₂O₂ dissolved all the cobalt and nickel, together with 9.6% of the copper. Cyanex 301 selectively extracted Cu(II) from the leaching solution, and copper ions were completely stripped with 30% aqua regia. Selective extraction of Co(II) from a Cu(II)-free raffinate was possible using the ionic liquid ALi-SCN. Three-stage cross-current stripping of the loaded ALi-SCN by a 15% NH₃ solution resulted in the complete stripping of Co(II). A process was proposed to separate the three metal ions from the sulfuric acid leaching solutions of metallic mixtures by employing solvent extraction.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.76-79
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• 2001

In Japan in of today, there is no aspect in which the quantity of waste glass bottle discharged from ordinary homes decreases. Moreover, the kind of shape and color of the waste glass bottles are increasing little by little. In the recycling of the glass bottle, it becomes a problem that many kind of the color is abounding. It is possible to use the transparent glass bottle as raw material of the glassware. Since the reproduction of the color is difficult, the colored glass bottle is not possible to use as a raw material. Therefore, the processing of these glass bottles entirely depends on the reclamation. In Japan, the security of the new reclaimed land is very difficult for the reason of the environmental damage. Moreover, the life expectancy in many reclaimed lands is anticipated with within two years. Therefore, the development of the processing method of glass bottle other than reclamation becomes a rapid problem. At present it is examined that it is used of an aggregate of the colored pavement, as one of the application methods of colored glass bottle. The particle size of produced glass aggregate is also 5mm or less, because the thickness is 5mm or less on almost glass bottles. And almost glass particles have the sharp tip. The application as the aggregate is limited for this sharpness of the particle. This study was carried out for the purpose of the establishment of sharpness measuring method of the glass aggregate particle. It is possible that the injury degree to human in the handling is known, if showing the sharpness of the aggregate particle at the objective numerical value is possible. And the application of the glass aggregate is spread. In this research, the balloon fracture method was used for the sharpness measurement of the glass particle. This method is based on the completely new idea, and it is possible to express completely the possibility of injury to the human. It is reported with the detailed result in full paper, because this study is continuous in order to get the JIS which is industrial standard of Japan.