• Applied Biological Chemistry
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• 제42권1호
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• pp.73-78
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• 1999

Acid mine drainage (AMD) results from sulfuric acid produced by the oxidation of pyrite, and contains large amounts of toxic elements. In the neutralization of AMD, iron and aluminum hydroxides are the major precipitates and those two can be separated with two-phase neutralization. In this study, removal of toxic elements by the two phases of neutralization was investigated using an AMD collected from the abandoned antimony mine in Gachang, Taegu. Contents of As, Cd, Cu, Mn, Pb and Zn in the AMD were higher than the criteria of river water quality or permissible waste water discharge. In the first phase, the AMD was neutralized to several % (25, 50, 75, 100, and 125) of $Fe(OH)_3$ equivalence point with solid $Ca(OH)_2$. In the second phase, the supernatant of the first phase neutralization was titrated to pH 7.5. After neutralization of the AMD to 100% of the $Fe(OH)_3$, equivalence point, most of Fe and Pb were removed but levels of As, Cd, Cu, Ni, Mn, and Zn were not reduced in the supernatant solution. In the second phase neutralization, levels of those toxic elements in the supernatants dropped below the wastewater discharge or river water quality criteria. This result suggests that the precipitate formed in the first phase of the neutralization process may be disposed without any special cares. Thus the two-phase neutralization scheme can reduce the cost of disposing precipitates containing toxic metals in comparison with the monophase neutralization scheme.

• Economic and Environmental Geology
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• 제41권1호
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• pp.33-45
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• 2008

Two types of reactor were designed to neutralize acid mine drainage flow from closed mine. Limestone used as a neutralizer, which composed mainly of calcite with small amount of dolomite. In general, the effect of neutralization depended upon both the position of reaction and the amount of supply of neutralizer. It was observed that the neutralization was enhanced as the reaction with acid mine drainage occurred at the upper part of reactor with sufficient supply of neutralizer. When the reaction was sustained in upper part of the reactor, the neutralizer was not affected by precipitates and the reaction could last until all of neutralizer was consumed.

• Journal of the Korean GEO-environmental Society
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• 제23권9호
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• pp.33-40
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• 2022

Sedimentation and pH neutralization has been investigated as preteatment of acid contaminate water. The settling and neutralizing process derive more effective degradation efficiency as the pre-treatment process before the removal process of adsorption, volatile, biodegradation, or oxidation. Settling velocity, uniformity coefficient, coefficient of curvature, and grain size index can define in the sedimentation process for characteristics of the soil. The stainless steel sieve has been used to separate each particle size of the dry soil by assembling in order of 4, 10, 20, 40, 80, 100, and 200 mesh sizes. The soil from Gamcheon Port in Busan drops upper side of the sieve and shakes back and forth to separate each different size of the particle. The 1L of Imhoff cone and 200 mL of the mass cylinder were used as settling tanks to calculate settling velocity. Stokes' equation was used to figure out the average density of dry soil with a value from settling velocity. In the results, the average particle density and lowest settling velocity were 1.93 g/cm³ and 0.11 cm/s, respectively. These values can detect the range of settling points of sediment to prevent chemical accidents. In pH neutralization, the initial pH of 2, 3, 4, and 5 of nitric acid and sulfuric acid are used as an acid solution; 0.1, 0.01, and 0.001 M of sodium hydroxide and calcium hydroxide are used as a base solution. The main goal of this experiment is to figure out the volume percentage of the acid solution becomes pH 7. The concentration of 0.001 M of base solution exceeds all the conditions, 0.01 M exceeds partially, and 0.1 M does not exceed 5 v/v% except pH 2. Calcium hydroxide present less volume than sodium hydroxide at pH neutralization both sulfuric and nitric acid.

• Applied Chemistry for Engineering
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• 제19권6호
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• pp.690-692
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• 2008

Pure glycerol could be obtained from a biodiesel byproduct by separation processes including neutralization, precipitation, and distillation. The contents of distilled glycerol through the above separation processes were measured and the results were compared according to experimental conditions such as acid concentration and precipitation temperature. Neutralization processes were carried out in the concentration range of 5~37 wt% hydrochloric acid, 5~95 wt% sulfuric acid, and 5~85 wt% phosphoric acid, respectively. Precipitation temperatures in neutralization were controlled in the range of 293~333 K. Higher values of the distilled glycerol content were obtained due to the salt removal in the pretreatment case of neutralization with 10 wt% sulfuric acid and precipitation of 313 K with 85 wt% phosphoric acid, respectively. The variations of acid concentration and precipitation temperature in pretreatment steps affected to some extent glycerol recovery from the biodiesel byproduct.

• Journal of Sensor Science and Technology
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• 제7권2호
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• pp.140-146
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• 1998

Methods and systems to remove static electricity are requested necessarily because the static electricity causes a flammable gas explosion, a fire, reduction of production rate in manufacturing VLSI semiconductor device and so on. In this paper, abrasion and dust contaminant of needle electrode are studied experimentally. And, frequencies and pulse durations of a high frequency pulse source were controlled effectively to minimize the abrasion of needle electrode and control generated numbers of ions. As a result, it is verified experimentally that the ion generation of charge neutralizer increases by using a high frequency pulse source.

• Clean Technology
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• 제3권2호
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• pp.74-86
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• 1997

Recently the treatment of industrial wastes by membrane processes has drawn much attention due to increasing demands for clean technology. In the process investigated in this study, metal species in the acidic wastes are precipitated as metal hydroxide forms in a neutralization tank, and acid and base solutions are regenerated by water-splitting electrodialysis(WSED) to be reused in the process. Material balances of the processes for treating pickle liquor and mixed wastewater were calculated to explain conceptual design of the process. Experiments for neutralization precipitation with KOH and NaOH for mixed wastewater were carried out to precipitate metal hydroxide and to recover salt solution as supernatant. Also WSED of the salt solutions producing acid and base was tested in 2 or 3 compartment stacks using KCl and NaCl to investigate the effects of stack configurations on the WSED performance.

• Korean Journal of Veterinary Research
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• 제32권1호
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• pp.83-90
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• 1992

Monoclonal antibodies against structural proteins of bovine viral diarrhea virus(BVDV) were derived by classical hybridoma techniques. These antibodies were characterized by serum neutralization, immunoblotting and immunoprecipitation. The neutralizing monoclonal antibody reacted with the 56kd to 54kd(M.W.) viral protein in western blotting and immunoprecipitation analysis. Although there was no neutralizing activity, another monoclanal antibody reacted with the 45kd protein by immunoprecipitation and with both the 45kd and 36kd proteins in immunoblotting analysis. respectively. Densitometer scanning of purified BVDV and the immunopreipitation of whole virus particles with neutralizing monoclonal antibody revealed the presence of more than twelve viral polypeptides. Although no possible precursor form of protein was identified with the neutralizing monoclonal antibody. the presence of intact virion was detected in the infected cell supernatant immediatelty after pulse labeling, indicating rapid translational processing as well as packaging of the virus. The partial peptide mapping of 45kd and 36kd proteins with Staphylococcus aureus V 8 protease showed that these two proteins are related.

• Journal of Soil and Groundwater Environment
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• 제7권4호
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• pp.68-76
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• 2002

In this study, we have investigated the geochemical behavior and fate of heavy metals in acid rock drainage (ARD). The ARD was collected from the area of the former Dongrae pyrophyllite mine. The Dongrae Creek waters were strongly acidic (pH : 2.3~4.2) and contained high concentrations of $SO_4$, Al, Fe, Mn, Pb, Cu, Zn, and Cd, due to the influence of ARD generated from weathering of pyrite-rich pyrophyllite ores. However, the water quality gradually improved as the water flows downstream. In view of the change of mole fractions of dissolved Fe, Al and Mn, the generated ARD was initially both Fe- and AA-ich but progressively evolved to more Al-rich toward the confluence with the uncontaminated Suyoung River. As the AR3 (pH 2.3) mixed with the uncontaminated waters (pH 6.5), the pH increased up to 4.2, which caused precipitation of $SO_4$-rich Fe hydroxysulfate as a red-colored, massive ferricrete precipitate throughout the Dongrae Creek. Accompanying the precipitation of ferricrete, the Dongrae Creek water progressively changed to more Al-rich toward downstream sites. At the mouth of the Dongrae Creek, it (pH 3.4) mixed with the Suyoung River (pH 6.9), where pH increased to 5.7, causing precipitation of Al hydroxysulfate (white precipitates). Neutralization of the ARD-contaminated waters in the laboratory caused the successive formation of Fe precipitates at pH<3.5 and Al precipitates at higher pH (4~6). Manganese compounds were precipitated at pH>6. The removal of trace metals was dependent on the precipitation of these compounds, which acted as sorbents. The pHs for 50% sorption ($pH_{50}$) in Fe-rich and Al-rich waters were respectively 3.2 and 4.5 for Pb, 4.5 and 5.8 for Cu, 5.2 and 7.4 for Cd, and 5.8 and 7.0 for Zn. This indicates that the trace metals were sorbed preferentially with increasing pH in the general order of Pb, Cu, Cd, and Zn and that the sorption of trace metals in Al-rich water occurred at higher pH than those in Fe-rich water. The results of this study demonstrated that the partitioning of trace metals in ARD is not only a function of pH, but also depends on the chemical composition of the water.

• Proceedings of the Korean Ceranic Society Conference
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• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
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• pp.153.1-153
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• 2003

• Applied Biological Chemistry
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• 제9권
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• pp.71-81
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• 1968

Defatted rice bran is mixed with diluted acid solution, the mixture is agitated some hrs. at constant temparature. After the mixture is filtered, thus filtrate is obtained. This filtrate is phytin extract solution. (Test-1) The alkali is added to this filtrate and filtered out, then the precipitation of phytin is obtained. (Test-2) At the test-1, the effect of kind of acid, conc. of acid, amount of extract sol'n., time of extraction, temp. of extraction, to the extract amount of phytin is tested. Consequently, the following facts are known. 1. Amount of phytin extract is greater HCI extraction than $H_{2}SO_4$ extraction. 2. At 0.3% HCI, the amount of phytin extract is greatest of all HCl extraction. 3. The sufficient amount of acid solution is 8-10 times of amount of defatted rice bran. 4. The time of extraction at room temperature is sufficient 8-12 hrs. 5. When extract temperature is $20-30^{\circ}C$, the amount of phytin extraction is greater of all temp. 6, When defatted rice bran 20 g is shanken with 160 ml of 0.3% HCl for 10 hr. at room temp., in this case the amount of phytin extract is 11.34% of defatted rice bran, it is 93% of theoretical yield. At the test-2 the effect of kind of precipitation agent, degree of nutralization to the amount of phytin prcipitation is tested. 1. Degree of nut. is best at pH 6.8-7.0. 2. When use of $Ca(OH)_2$ the amount of phytin precipitation is more than use of KOH, NaOH, or $NH_{4}OH$. 3. At pH 6.0-7.2, the solubility of phytin is followed. K-phytate > $NH_{4}-phytate$ > Na-phytate > Ca-phytate 4. When phytin extract solution is nutralized with $Ca(OH)_2$ to pH 7.0, the amount of phytin precipitation is 94.78% of theoretical yield.