• Archives of Pharmacal Research
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• v.18 no.5
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• pp.314-319
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• 1995

Antacid granules were prepared by agglomeration and powder method in high speed agitation type granulator. The copmositions of the test antacids were sodium bicarbonate nad magnesium carbonate nad a coating material was powder of polyvinylacetal diethyl-aminocacetate (AEA) and an additive material was talc powder. The dissolution characteristics of base from the antacid granules were investigated to evaluate neutralization capacity of hydrochloric profile of base and neutralization behavior, the following results were obtained : The prepared granules showed a pH-dependent dissolution pattern of a base. The dissolution profile of a base was varied with addition of talc powder as well as coating amount of AEA. The relationship between the ratio of dissolution retarded time for 20% and 10% AEA. The relationship between the ratio of dissolution retarded time for 20% AEA coated granules $\theta_{20}/\theta_{10}$ and the diameter reduction of the granules was explained by the rate process of neutralization of hydrochloric acid.

• Journal of Wetlands Research
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• v.23 no.1
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• pp.54-59
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• 2021

DIWS system was introduced to remove hydrogen sulfide from the biogas of wastewater treatment plant. In the case of using water into the DIWS system more than 5,000mg/L of hydrogen sulfide, 25% of H2S removal efficiency was shown and required such further treatment process as incineration which was obtained more than 98%. When the inflow of hydrogen sulfide was 5,000mg/L, CH4 and CO2 were effectively discharged and the reduction was 8.7% and 28.6%, respectively. When such neutralization chemicals as Na2CO3 and NaOH were introduced into the DIWS system, H2S was removed more than 97.2% keeping pH in the range of 11.2 to 11.5.

• 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.

• Journal of the Korean GEO-environmental Society
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• v.23 no.9
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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.

• Journal of Animal Environmental Science
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• v.18 no.sup
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• pp.13-20
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• 2012

This research investigated the effect of $SCOD_{Mn}$ concentrations and pH adjustment at the stage before land application, namely 2nd-aeration treatment stage of liquid fertilizer in the liquid fertilizer treatment process of swine manure on the physicochemical compositions of 2nd-aeration treated liquid fertilizer. The liquid fertilizer used in this research is the alkaline fermented liquid fertilizer of swine manure more than pH 9.0 through aeration treatment (Alkaline fermentation treatment group). About the alkaline liquid fertilizer, phosphate neutralization treatment was conducted with phosphoric acid and it was a phosphate neutralization treatment group. In 2nd-aeration treatment of liquid fertilizer for 30 days, each group was divided into alkaline treatment groups (T-1, T-2, and T-3) and phosphate neutralization treatment groups (T-4, T-5, and T-6) according to early $SCOD_{Mn}$ concentrations. The research results are as follows. 1. As for $SCOD_{Mn}$ reduction rate, the average 29.9% in alkaline treatment groups and the average 36.9% in phosphate neutralization treatment groups were shown and so the relatively high reduction rate was shown in phosphate neutralization treatment groups. 2. After finishing the experiment, the group of the lowest $SCOD_{Mn}$ concentrations was the phosphate neutralization treatment group, T-6 with the lowest inflow concentrations. In case the final goal level of 2nd-aeration treated liquid fertilizer is assumed as concentrations less than $SCOD_{Mn}$ 3,000 ppm, it would be desired that inflow concentrations of 2nd-aeration treatment groups are adjusted less than $SCOD_{Mn}$ 5,500 ppm. 3. As for the persistence rate of nitrogen, the average 29.3% in alkaline treatment groups and the average 38.9% in phosphate neutralization treatment groups were shown and so phosphate neutralization treatment groups showed the relatively low loss rate of nitrogen, meanwhile, in the case of T-P, phosphate neutralization treatment groups maintained high concentrations (average 1,473 ppm). 4. In the event of 2nd-aeration treatment of liquid fertilizer, "alkaline fermentation treatment" condition in 'low phosphate-low nitrogen' type and "phosphate neutralization treatment" condition in 'high phosphate-high nitrogen' type are expected to be favorable.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.31-38
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• 2007

Recently produced concrete has a tendency to overcome environmental defects. Porous and planting Eco-concrete requires the neutralization process and enough void in concrete to contain water, to pass air freely, and provides necessary nutrients to vegetation roots. The biological environment in concrete is not suitable for planting because the concrete possesses strong alkali constituent of pH 11-13. This study evaluated the strength and serviceability of concrete as well as the chemical characteristics of concrete mixed by low-grade iron ore left in the abandoned mine and treated by Ammonium monohydrogen phosphate, $(NH_4)_2HPO_4$. Test variables include two kinds of coarse aggregates such as crushed stones and low-grade iron ore, the duration time and the period for neutralization treatment by Ammonium monohydrogen phosphate, $(NH_4)_2HPO_4$, and the proportion ratio of cement, blast furnace slag and silica fume.

• Corrosion Science and Technology
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• v.8 no.3
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• pp.110-115
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• 2009

At the onset of corrosion of steel in concrete, hydrogen ions usually evolve in the process of electrochemical reaction, thereby decreasing the pH of the pore solution, which can be buffered by cement hydration products, as being representatively illustrated by calcium hydroxide. Hence, a fall in the pH is dependent on properties of cement hydration (i.e. hydration products and degree of hydration). The present study tested acid neutralization capacity (ANC) of cementitious binders of OPC(Ordinary Portland Cement), 30% PFA(Pulverized Fuel Ash), 60% GGBS(Ground Granulated Blast Furnace Slag), 10% SF(Silica Fume) to quantify the resistance of cement matrix to a pH fall. Cement pastes were cast at 0.4 of a free W/C ratio with 1.5% chlorides by weight of binder in cast. Powder samples obtained crushed and ground specimen after 200 days of curing were diluted in still water combined with different levels of 1M nitric acid solution, ranging from 0.5 to 20 mol/kg. Then, the pH of diluted solution was monitored until any further change in the pH did not take place. It was seen that the pH of the diluted solution gradually decreased as the molar amount of nitric acid increased. At some particular values of the pH, however, a decrease in the pH was marginal, which can be expressed in the peak resistances to a pH fall in the ANC curve. The peaks occurred at the variations in the pH, depending on binder type, but commonly at about 12.5 in the pH, indicate a resistance of precipitated calcium hydroxide. The measurement of water soluble chloride at the end of test showed that the amount of free chloride was significantly increased at the pH corresponding to the peaks in the ANC curve, which may reflect the adsorption of hydration products to chlorides.

• Journal of the Korean Society of Groundwater Environment
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• v.2 no.1
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• pp.38-47
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• 1995

This study was carried out in order to provide basic information on neutralization processes of acid mine drainage (AMD) from the abandoned Donghae coal mine in the Samchuk coalfield. The contents of potentially toxic elements in stream water increase and the level of pH decreases during dry season. Hydrated lime is turned out to be the best neutralizer of the acid mine water from a technical and economic viewpoint. From the results of equilibrium calculation, Fe and Al could be precipitated as FeOOH, and Al(OH)$_3$, respectively, in the neutralization process. The sites of holding basins necessary to equalize quantity and quality of AMD are recommended by GIS analysis, and the capacities of holding basins are determined by hydrological calculation.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.393-402
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• 1999

Precipitation samples were collected by the wet-only sampling method in Iksan in the northwest of Chonbuk from March 1995 to February 1997. These samples were analyzed for the concentration of ion components, in addition to pH and electrical conductivity. The annual mean pH of precipitation was 4.8 and the seasonal trend of pH was shown to be low in Fall and Winter(4.5), middle-ranged in Spring(4.7) and high in Summer(5.0). The frequency of pH below 5.6 was about 71%. The seasonal pattern of pH frequency was found to be different in each season. In the case of the pH less than 5.0, the frequency was higher in Spring, Fall and Winter than in Summer, especially higher in Fall than in other seasons. The concentrations of analysed ions showed a pronounced seasonal pattern. However, major ion species for all seasons were $NH^+_4,;Ca^{2+};and;Na^+$ among cations and $SO^{2-}_4,;Cl^-;and;NO^-_3$ among anions. The major acidifying species appeared to be $nss-SO^{2-}_4;and;NO^-_3$, and the main bases responsible for the neutralization of precipitation acidity were $nss-Ca^{2+};and;NH^+_4$. The potential acidity of precipitation, pAi, was found to be between 3.0 and 5.0 for total samples, while the measured pH was approximately between 3.9 and 7.8. The seasonal trend of pAi showed a decreasing order: Summer (4.3), Winter(4.0), Spring and Fall(3.8). During the Fall, both pAi and pH were especially very low, which indicated that during this period the potential acidity of precipitation was high but the neutralizing capacity was low. For Spring, pAi was very low but pH was slightly high. This was likely due to the large amount of $CaCO_3$ in the soil particles transported over a long range from the Chinese continent that were incorporated into the precipitation, and then neutralized the acidifying species with its high concentraton.

• Corrosion Science and Technology
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• v.3 no.1
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• pp.26-29
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• 2004

Metal plated plastics are becoming more prevalent in materials of communication parts. A new technique MmSH is a process of injecting plastics to produce innovated physical properties compared to the conventional injection process. This study involves two ways of coating plastics Ni by electroless plating and varying bath and plasma treatment for improved adhesion strength between plating layer and surface. MmSH injection processed ASS with plasma treated after neutralization showed a superior adhesion force and a gloss and rate of deposition when it was in pH 7.5. On the other hand, conventional injection processed ASS was in pH 6.5.