• Title/Summary/Keyword: pH values

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Ionic Equilibria in Mixed Solutions of Cuprous and Cupric Chloride (염화 제1구리와 제2구리 혼합용액의 이온평형)

  • Lee, Man Seung;Nicol, M.J.
    • Korean Journal of Metals and Materials
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    • v.46 no.1
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    • pp.20-25
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    • 2008
  • The ionic equilibira in mixed solutions of cuprous and cupric chloride were analyzed by considering chemical equilibria, mass and charge balance equations. The activity coefficients of solutes were calculated by using Bromley equation. Required thermodynamic constants and interaction parameters were evaluated from the data reported in the literature. The effect of NaCl and CuCl concentrations on the pH and potential of the mixed solutions was explained in terms of the variation in the concentration of solutes and in the activity of hydrogen ion. The calculated pH values of the mixed solutions agreed well with the measured values. However, the calculated values for the potential of the mixed solutions were lower than the measured values, indicating the necessity of considering the complex formation between cuprous and chloride ion, such as $Cu^2Cl{_4}^{2-}$ and $Cu_3Cl{_6}^{3-}$.

PH Characteristics of Precipitation in Seoul Area (서울 지역에 내린 우수 pH 특성)

  • Lee, Min-Hee;Eiji, Hirai;Motoichi, Miyazaki;Tetsuri, Chahji;Hao, Quan
    • Journal of environmental and Sanitary engineering
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    • v.9 no.2
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    • pp.1-7
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    • 1994
  • Rainwater was collected in Seoul area from January 1991 to December 1993 (over 3years) and by the analysis of the chemical components contained in rainwater, investigated the components that effect on rainwater pH Through the above studies the following conclusions were obtained. 1) Method for Averaging pH Volume weighted method is considered to be acceptable providing that precipitation is measured at the same time when the samples are taken, without precipitation data a simple averaging method should be the next choice. 2) Annual average rainwater pH was 4.98 in 1991, 4.80 in 1992, 4.67 in 1993, measurement range was 3.6-8.1. 3) In the relationship between rainwater pH and rainfall amounts rainwater pH for light rain(<15mm rainfall) was existent in the wide range(pH 4-7), but for heavy rain was corresponded to the annual average values. 4) Annual frequency of pH was Birrndat the frequency($\gamma $) between the density of the [$H^{+}$] and pH in the rainwater(over 3years ), $NO_{3}^{-}$ was excellent and the obtained results was 0.62 in 1992. Also In the correlation coefficient($\gamma $) according to the pH range $SO_{4}^{2-}, NO_{3}^{-}$, were 0.85 ,0.68 at 3.6 $Cl^-$ was 0.99(1993). At 4.1$NO_{3}^{-}(\gamma=0.48)$ in 1992, SO_4^{2-}($\gamma$=0.54), $NO_{3}^{-}(\gamma$=0.72), $Cl^- (\gamma$=0.49) in 1993. 6) pH values gradually increased with increase in $Ca^{2+}/SO_{4}^{2-}$.

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Adsorption Characteristics of Cd(II) and Cu(II) by Zeolites Synthesized from Hwangto (황토로부터 합성한 제올라이트에 의한 Cd(II) 및 Cu(II) 흡착특성)

  • 감상규;홍정연;허철구;이민규
    • Journal of Environmental Science International
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    • v.12 no.7
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    • pp.817-824
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    • 2003
  • Various kinds of zeolites, such as analcime (ANA), cancrinite (CAN), Na-Pl and sodalite octahydrate (SOD) could be synthesized from Hwangto by hydrothermal reaction in a high-pressure vessel. The adsorption characteristics of Cu(II) and Cd(II) by Hwangto and its synthetic zeolites were investigated using the chemical and electrochemical surface parameters of these adsorbents. The heavy metal adsorptivity among the adsorbents decreased in the following sequences: Na-Pl > SOD > ANA > CAN > Hwangto. This sequence was the same with the values of surface site density (Ns) of these adsorbents and was correlated inversely with the values of pHpzc (pH of the point of zero charge) and the va]ues of K$\_$a2/(int) (intrinsic surface deprotonation constant) of the adsorbents for synthetic zeolites, i.e., the adsorbents with higher values of Ns and with lower values of pHpzc and K$\_$a2/(int) for synthetic zeolites showed higher heavy metal adsorptivity. With increasing pH, the heavy metal adsorptivity increased greatly between pHpzc and pH 6 or 7 because of the steep increase of negatively charged sites for synthetic zeolites, but for Hwangto, it increased broadly because of slow increase of negatively charged sites based on its lower surface sites.

The Study on Emulsifying and Foaming Properties of Buckwheat Protein Isolate (분리 메밀 단백질의 유화 및 기포특성에 관한 연구)

  • 손경희;최희선
    • Korean journal of food and cookery science
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    • v.9 no.1
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    • pp.43-51
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    • 1993
  • Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.

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Glass Dissolution Rates From MCC-1 and Flow-Through Tests

  • Jeong, Seung-Young
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.06a
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    • pp.257-258
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    • 2004
  • The dose from radionuclides released from high-level radioactive waste (HLW) glasses as they corrode must be taken into account when assessing the performance of a disposal system. In the performance assessment (PA) calculations conducted for the proposed Yucca Mountain, Nevada, disposal system, the release of radionuclides is conservatively assumed to occur at the same rate the glass matrix dissolves. A simple model was developed to calculate the glass dissolution rate of HLW glasses in these PA calculations [1]. For the PA calculations that were conducted for Site Recommendation, it was necessary to identify ranges of parameter values that bounded the dissolution rates of the wide range of HLW glass compositions that will be disposed. The values and ranges of the model parameters for the pH and temperature dependencies were extracted from the results of SPFT, static leach tests, and Soxhlet tests available in the literature. Static leach tests were conducted with a range of glass compositions to measure values for the glass composition parameter. The glass dissolution rate depends on temperature, pH, and the compositions of the glass and solution, The dissolution rate is calculated using Eq. 1: $rate{\;}={\;}k_{o}10^{(ph){\eta})}{\cdot}e^{(-Ea/RT)}{\cdot}(1-Q/K){\;}+{\;}k_{long}$ where $k_{0},\;{\eta}$ and Eaare the parameters for glass composition, pH, $\eta$ and temperature dependence, respectively, and R is the gas constant. The term (1-Q/K) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_{0},\;{\eta}\;and\;E_{a}$ are the parameters for glass composition, pH, and temperature dependence, respectively, and R is the gas constant. The term (1-Q/C) is the affinity term, where Q is the ion activity product of the solution and K is the pseudo-equilibrium constant for the glass. Values of the parameters $k_0$, and Ea are determined under test conditions where the value of Q is maintained near zero, so that the value of the affinity term remains near 1. The dissolution rate under conditions in which the value of the affinity term is near 1 is referred to as the forward rate. This is the highest dissolution rate that can occur at a particular pH and temperature. The value of the parameter K is determined from experiments in which the value of the ion activity product approaches the value of K. This results in a decrease in the value of the affinity term and the dissolution rate. The highly dilute solutions required to measure the forward rate and extract values for $k_0$, $\eta$, and Ea can be maintained by conducting dynamic tests in which the test solution is removed from the reaction cell and replaced with fresh solution. In the single-pass flow-through (PFT) test method, this is done by continuously pumping the test solution through the reaction cell. Alternatively, static tests can be conducted with sufficient solution volume that the solution concentrations of dissolved glass components do not increase significantly during the test. Both the SPFT and static tests can ve conducted for a wide range of pH values and temperatures. Both static and SPFt tests have short-comings. the SPFT test requires analysis of several solutions (typically 6-10) at each of several flow rates to determine the glass dissolution rate at each pH and temperature. As will be shown, the rate measured in an SPFt test depends on the solution flow rate. The solutions in static tests will eventually become concentrated enough to affect the dissolution rate. In both the SPFt and static test methods. a compromise is required between the need to minimize the effects of dissolved components on the dissolution rate and the need to attain solution concentrations that are high enough to analyze. In the paper, we compare the results of static leach tests and SPFT tests conducted with simple 5-component glass to confirm the equivalence of SPFT tests and static tests conducted with pH buffer solutions. Tests were conducted over the range pH values that are most relevant for waste glass disssolution in a disposal system. The glass and temperature used in the tests were selected to allow direct comparison with SPFT tests conducted previously. The ability to measure parameter values with more than one test method and an understanding of how the rate measured in each test is affected by various test parameters provides added confidence to the measured values. The dissolution rate of a simple 5-component glass was measured at pH values of 6.2, 8.3, and 9.6 and $70^{\circ}C$ using static tests and single-pass flow-through (SPFT) tests. Similar rates were measured with the two methods. However, the measured rates are about 10X higher than the rates measured previously for a glass having the same composition using an SPFT test method. Differences are attributed to effects of the solution flow rate on the glass dissolution reate and how the specific surface area of crushed glass is estimated. This comparison indicates the need to standardize the SPFT test procedure.

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Dual Sorption of Orange II by Silk Fibroin (견섬유에 대한 Orange II의 이원 수착)

  • 탁태문
    • Journal of Sericultural and Entomological Science
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    • v.24 no.2
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    • pp.81-84
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    • 1983
  • The equilibrium sorption of Orange II by silk fibroin in the range of 50$^{\circ}$, 70$^{\circ}$, 90$^{\circ}C$ and to pH 1.5, 2.2, and 4.0 have been discussed in the light of the dual sorption. Langmuir sorption constant K$\_$L/ and partition coefficient K$\_$P/ were decreased with the increase of the temperature and the pH for the dyeing of silk fibroin with Orange II. Positive values for adsorption entropy were observed. It was found that the values of $\Delta$H$^{\circ}$ is negative for dyeing conditions, and the dyestuff/fibre reaction is therefore exothermic.refore exothermic.

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Variation of the Nanostructural and Optical Features of Porous Silicon with pH Conditions (pH 조건에 따른 기공성 실리콘의 나노구조 및 광학적 특성의 변화)

  • Kim, Hyo-Han;Cho, Nam-Hee
    • Journal of the Korean Ceramic Society
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    • v.50 no.4
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    • pp.294-300
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    • 2013
  • The effect of chemical treatments of porous silicon in organic solvents on its nanostructural and optical features was investigated. When the porous Si was dipped in the organic solvent with various PH values, the morphological, chemical, and structural properties of the porous silicon was sensitively affected by the chemical conditions of the solvents. The size of silicon nanocrystallites in the porous silicon decreased from 5.4 to 3.1 nm with increasing pH values from 1 to 14. After the samples were dipped in the organic solvents, the Si-O-H bonding intensity was increased while that of Si-H bonding decreased. Photoluminescence peaks shifted to a shorter wavelength region in the range of 583 to 735 nm as the pH value increased. PL intensity was affected by the size as well as the volume fraction of the nanocrystalline silicon in the porous silicon.

Relationship between the Micellization of TTAB and the Solubilization of p-Bromophenol in TTAB Solution (TTAB 용액에서 p-브로모페놀의 가용화와 TTAB의 미셀화와의 상관관계에 대한 연구)

  • Lee, Byung-Hwan
    • Journal of the Korean Chemical Society
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    • v.57 no.6
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    • pp.665-671
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    • 2013
  • The solubilization of p-bromophenol by the micellar system of TTAB(tetradecyltrimethylammonium bromide) and the micellization of TTAB were studied by the UV-vis spectrophotometric method simultaneously. And the effects of temperature on these properties have been measured for the thermodynamic study. The results show that the ${\Delta}G_s{^o}$ and ${\Delta}H_s{^o}$ values are negative and the ${\Delta}S_s{^o}$ values are positive for the solubilization of p-bromophenol within the measured range. On the other hand, the ${\Delta}G_m{^o}$ values are negative and the ${\Delta}H_m{^o}$ and ${\Delta}S_m{^o}$ values are positive for the micellization of TTAB. The effects of additives such as n-butanol and NaCl have been studied also for both properties and the relationship between these two properties has been also studied. From the results, we can postulate the solubilization site of p-bromophenol in the micelle.

Solubilization of Benzenesulfonate anion and Its Derivatives by the Micellar System of TTAB (TTAB 용액에서 Benzenesulfonate 음이온과 유도체들의 가용화에 대한 연구)

  • Lee, Byung-Hwan
    • Journal of the Korean Chemical Society
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    • v.45 no.1
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    • pp.7-13
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    • 2001
  • The interaction of benzenesulfonate anion and its derivatives ($C_6H_5SO_3^-, p-$CH_3C_6H_4SO_3^-, and $p-C_2H_5C_6H_4SO_3^-$) with the micellar system of cationic surfactant TTAB(tetradecyltrimethylammonium bromide) was studied by UV/Vis spectrophotometric method. The solubilization constants($K_s$) of benzenesulfonate anions into the micellar phase of this surfactant have been measured with the change of temperature. The effects of additives(n-pentanol and NaBr) on the solubilization of benzenesulfonate anions by this surfactant system have been also measured. There was a great decrease on the values of $K_s$ and CMC simultaneously with these additives so that the measured values of ln$K_s$ were linear relationships with the values of lnCMC. For the thermodynamic study, various thermodynamic parameters(${\Delta}G^0_s$, ${\Delta}H^0_s$ and ${\Delta}S^0_s$) have been calculated and analyzed from the dependence of Ks values on temperature.

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Effects of Heating Temperature and Time, Salt and pH on the Texture and Color Characteristics of Whole Egg Gel (계란찜의 텍스쳐와 색에 미치는 가열온도와 시간, pH 및 소금의 영향)

  • 김경미;김종군;김주숙;김우정
    • The Korean Journal of Food And Nutrition
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    • v.17 no.2
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    • pp.163-170
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    • 2004
  • Effect of several factors for Preparation of whole egg gel (WEG) on texture and color of WEG were investigated in this study. The factors studied were amount of water addition, heating temperature and time, pH and NaCl. The whole egg gel was prepared by mixing of whole egg and steaming at 100$^{\circ}C$ for 7 min followed by cooling at 22$^{\circ}C$ for 90 min. The results showed that the increase in water addition decreased significantly with viscosity values of whole egg solution (WES) and the addition of more than 50% water resulted in a significant decrease in the stress at failure (SF) and the hardness of WEG. The color a and b values of WES decreased and the value of WEG also decreased significantly in negative range. The increase in heating temperature decreased the coagulation time and increased in SF while SF decreased. Addition of NaCl up to 1.3% resulted a significant increase in SF and hardness and a little changes in color of WEG. As the pH of WES changed from 4.0 to 10.0, the viscosity of WES was minimal and SF and hardness were maximal at pH 6.0. The L and b values of WEG were significantly reduced at higher pH values of 8.0.