• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.20 no.3
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• pp.153-159
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• 2017

Purpose: Acid neutralization during chemical clearance is significantly prolonged in children with cystic fibrosis, compared to symptomatic children without cystic fibrosis. The absence of available reference values impeded identification of abnormal findings within individual patients with and without cystic fibrosis. The present study aimed to test the hypothesis that significantly more children with cystic fibrosis have acid neutralization durations during chemical clearance that fall outside the physiological range. Methods: Published reference value for acid neutralization duration during chemical clearance (determined using combined impedance/pH monitoring) was used to assess esophageal acid neutralization efficiency during chemical clearance in 16 children with cystic fibrosis (3 to < 18 years) and 16 age-matched children without cystic fibrosis. Results: Duration of acid neutralization during chemical clearance exceeded the upper end of the physiological range in 9 of 16 (56.3%) children with and in 3 of 16 (18.8%) children without cystic fibrosis (p=0.0412). The likelihood ratio for duration indicated that children with cystic fibrosis are 2.1-times more likely to have abnormal acid neutralization during chemical clearance, and children with abnormal acid neutralization during chemical clearance are 1.5-times more likely to have cystic fibrosis. Conclusion: Significantly more (but not all) children with cystic fibrosis have abnormally prolonged esophageal clearance of acid. Children with cystic fibrosis are more likely to have abnormal acid neutralization during chemical clearance. Additional studies involving larger sample sizes are needed to address the importance of genotype, esophageal motility, composition and volume of saliva, and gastric acidity on acid neutralization efficiency in cystic fibrosis children.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.4
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• pp.481-486
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• 1994

The effect of neutralization of urea-treated rice straw with sulfuric acid was investigated. Long-cut (15-20 cm) and short-cut (2-3 cm) rice straw were treated with 6% urea for 21 days, and the treated straw was mixed with an acid-molasses solution to neutralize free ammonia and kept airtightly in a plastic bag for 24 hours. The neutralized and non-neutralized straw were dried and subjected to chemical analysis and in vitro dry matter (DM) digestibility determination. The in vitro DM digestibility as well as crude protein (CP) content were remarkably improved by neutralization. Short-cutting of the straw before treatment gave a better result than the long-cut samples. Neutralization with sulfuric acid also affected the chemical composition and increased sulfur content of samples. The CP thus fixed by neutralization was proven to be kept stable for 3 months, and in vitro DM digestibility was not affected by the storing period.

• Applied Biological Chemistry
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• v.42 no.1
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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.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.109-112
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• 2022

Lime has been used for the neutralization of acidic waste because it is cheap and available in large quantities. The resulting sludge often contains a considerable amount of unreacted lime due to alkali overdosing, even during automatic neutralization processes, which mainly arises from the poor solubility of lime. The sludge cake from lime neutralization of Ilkwang Mine also contained high percentages of calcium and magnesium. The elemental content of the sludge cake was compared with those obtained from a simulation of the lime neutralization facility installed at Ilkwang Mine. A Goldsim^® model estimated the degree of lime overdosing to be 19.1% based on the fractions of ferrous oxide. The analysis suggests that resolubilization of aluminum hydroxide could occur in the settling basin, in which pH exceeded 10 due to the continued dissolution of the overdosed lime. The present study demonstrated that chemical analysis of sludge combined with process simulation could provide a reasonable estimate of mass balance and chemistry in a neutralization facility for acid mine drainage.

• Clean Technology
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• v.17 no.2
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• pp.175-180
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• 2011

A novel multi-criteria decision making strategy is developed for the construction of industrial symbiosis network in eco-industrial park and the strategy is applied to the construction of acid/alkali wastewater neutralization network in Yeosu industrial complex. Acid (or alkali) wastewater is commonly generated in chemical industries, and it can be used as neutralizing agent for alkali (or acid) wastewater generated from another source. As a consequence, a large-scale industrial symbiosis network for wastewater neutralization can be constructed in petrochemical complexes where a large amount of acid/alkali wastewater is generated. In this study, substance flow model is constructed which describes the wastewater neutralization network and multi-criteria decision making strategy is applied to find a few candidate for industrial symbiosis network.

• Journal of Korean Society of Forest Science
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• v.90 no.1
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• pp.133-138
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• 2001

Increased base cation loss and Al mobilization, a consequence of soil acid neutralization responses, are common in air polluted areas showing forest decline. The prediction models of acid neutralization responses were developed by using indicators of soil acidification level(pH, and base saturation) in order to assess the forest soil sensitivity to acidification. The soil acidification level was greatest in Namsan followed by Kanghwa, Ulsan, and Hongcheon, being contrary to regional total $ANC_H$ pattern through soil columns leached with additional acid ($16.7mmol_c\;H^+/kg$), Both base exchange and Al dissolution were main acid neutralization processes in all study regions. There were low base exchange and high Al dissolution in the regions of the low total $ANC_H$. The $ANC_M$ by sulfate adsorption was greatest in Hongcheon compared with other regions even though the AN rate was very low as 6.4%. Coefficients of adjusted determination of simple and multiple regression models between soil acidification level indicators and the acid neutralization responses were more than 0.52(p<0.04) and 0.89(p<0.01), respectively. The result suggests that soil pH and base saturation are available indicators for predicting the acid neutralization responses. These prediction models could be used as an useful method to measure forest soil sensitivity to acidification.

• Applied Chemistry for Engineering
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• v.19 no.6
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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 Science Education
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• v.33 no.2
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• pp.317-320
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• 2009

I investigated Korean college students' conception about the volume change of solution when they detected the equivalence point during acid/base titration experiment using method of volume measurement. According to this study, most college students had a misconception that the volume increment was due to the formation of water by neutralization during acid/base titration. However, this is not enough to explain the volume change, neglecting contribution of a salt in solution. I calculated the partial molar volume of NaCl formed to explain the volume increment of solution during HCl/NaOH neutralization. Comparing the result of experiment with the calculation of partial molar volume, I elucidated that the main effect of volume increment was due to the partial molar volume of NaCl formed during HCl/NaOH neutralization. Here I propose to introduce college students to the concept of partial molar volume of the salt formed to reduce misconception about the volume change of solution during acid/base neutralization.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.187-194
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• 2000

One of effective utilization technique of rice husk is known to carbonize it for using as the culture materials. A series of study on the production of carbonized rice husk by a cyclone combustor shows that the carbonized rice husk produced have a strong alkalinity. Therefore, carbonized rice husk produced by a cyclone combustor is required to neutralize with proper normality. This work is the third part of a series on the production of carbonized rice husk by a cyclone combustor. In this work, the development of neutralization process was carried out in the range of experimental conditions recommended in the previous study. Those include the preheat temperature of combustion chamber of T1b=1273∼1373K, equivalence ratio =1.68∼2.17, auxiliary gas flow rates Qg=5.15∼6.43$\ell$/min. The injection technique of dilute acid was employed for neutralization. At the lower position of the outside of combustor, a dilute nitric acid selected as neutralization liquid was injected to the carbonized rice husk exhausted from the combustion chamber. The normalities of dilute nitric acid were varied to 0.01, 0.03 and 0.05N, respectively. The injection flow rates of the solution were changes from 1.7∼4$\ell$/min. The required carbonized and neutralized rice husk could be obtained at the dilute nitric acid with normality of 0.3N and flow rate of dilute nitric acid of 2∼3.5$\ell$/min. However, the carbonized and neutralized rice husks of about 10∼20% were destroyed by spray with high injection pressure.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.139-140
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• 2023

In this study, red mud with low recyclability was manufactured as liquid red mud, neutralized with sulfuric acid and nitric acid, and then added to cement paste to conduct research on physical and chemical properties. As a result, liquid red mud-added cement paste neutralized with sulfuric acid and nitric acid showed higher compressive strength after one day than cement paste with plain and non-neutralized liquid red mud. This indicates that nitric acid and sulfuric acid neutralization can increase initial strength.