• Journal of the Korean Society of Groundwater Environment
• /
• v.4 no.1
• /
• pp.14-19
• /
• 1997

Laboratory experiments were conducted to study the effects of pH and salt level on the soil sorption equilibrium of pentachlorophenol (PCP) which is hydrophobic and ionogenic. Experimental results indicated that the sorption equilibrium constant (Kp) of PCP increased with decreasing pH. A quantitative sorption model involving linear isotherms was estabilished to predict the pH effect on the PCP sorption equilibrium over the pH range from 3 to 8. The model prediction was in good agreement with the experimental data. Also, the Kp increased with salt concentration over the entire pH range. At added salt levels less than 0.1M, increase in Kp was larger than when the added levels were higher than 0.1M. Salt might increase the PCP sorption by inducing 'salting out-effect' or by forming deprotonated PCP-cation ion pairs such as PCP$\^$-/K$\^$＋/. Taking the pH range (5-8) and the salt content (up to 50 g/L) in the groundwater of Metropolitan landfill sites into consideration, the results indicated that the retardation factor of PCP in this area might range from 3 to 550 depending upon pH and salt content.

• Journal of Sericultural and Entomological Science
• /
• v.31 no.2
• /
• pp.121-126
• /
• 1989

Two kinds of solution for the measurement of solubilities of Sericin are prepared as followings at temperature 90 deg. C. One has the total carbonate concentration as 0, 50, 100mg CO2/l prepared with non-carbonate distilled water, sodium hydrogen carbonate and 0.1N HCI and NaOH, the other has total hardness, that is, calcium hardness or magnesium hardness as 0, 20, 50, 100mg CaCO2/l respectively prepared with non-carbonate distilled water, calcium carbonate and magnesium oxide. Solubilities of Cocoon layer Sericin at above solution gives following results ; 1. pH shows little effect on the solubility of Sericin at the non-carbonate solution but at the carbonate solution pH shows a sensitive effect on the solubility of Sericin. These means that pH controls the concentration of H2CO3, HCO3-and CO32- which prevent and promote the solution of Sericin. 2. After the cocoon layer treatment at the solution, the initial pH of 4.0, 7.0, 9.0 of the solution changed to 6.0-6.5 at the lower total carbonate solution. However in the higher total carbonate solution pH did not changed very much. This may be explained by the buffer action of carbonate. 3. The effect of the hardness on the solubility of Sericin was not found in the non-carbonate solution with the standard hardness after treatment of cocoon layer.

• Journal of Veterinary Clinics
• /
• v.18 no.4
• /
• pp.363-367
• /
• 2001

Shampoos are used routinely by a large number of veterinarians to treat skin diseases. Skin pH is affected by shampoos, however, known to occur. In order to evaluate the effect of shampoos on skin surface pH, we performed the measurement of skin pH using skin pH meter PH900 in five healthy mixed breed dogs. The seven commercial shampoos: Humilac, Sebocalm, Sebolytics, Etiderm, PEroxyderm, HyLyt and Zn-7 Derm were included in this study. The anatomical sites, right thorax was the highest pH (7.66$\pm$0.10), and the lowest pH (6.20$\pm$0.23) was left pinna. A statiscally significant decrease in skin pH was found 7 minutes after application of Humilac, Sebocalm, Etiderm, Peroxyderm (p<0.01) and Sebolytics (p<0.05). After 17 minutes of application skin surface pH was inclined to increase in every shampoos but the degree of increase was slight at 77 minutes. No statiscally significant differences were found in HyLy-T and Zn-7 Derm, but skin pH was normal range (6.2-7.8) after application. Throughout the experiment skin surface pH was maintained above pH 7.0 in detergent. The commercial shampoos, Humilac, Sebocalm, Etiderm, had the decreasing effect on skin surface pH in dogs. The other four shampoos maintain the skin pH normal range. The skin pH meter PH 900 was found simple and useful for skin pH measurement.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.21 no.6
• /
• pp.655-661
• /
• 2015

This study intends to evaluate the effect of nitric acid($HNO_3$) spill accidents on the marine ecosystem, while $HNO_3$ is known as one of the typical HNS. For this purpose, we performed (1) the growth inhibition test by using phytoplankton(Skeletonema costatum), (2) acute and chronic toxicity test by using invertebrate(Brachionus plicatilis and Monocorphium acherusicum), (3) fish(Cyprinodon variegatus) and (4) bacteria(Vibrio fischeri). In these tests, we observed the (1) pH changes induced by the nitric acid spill and (2) changes in nitrate($NO_3$) concentration disassociated from nitric acid after the accident, respectively. The toxicity test result on pH changes induced by $HNO_3$ shows that the no observed effect concentration(NOEC), lowest observed effect concentration(LOEC) and 50 % effect concentration($72h-EC_{50}$) values of M. acherusicum are pH 7 (0.3 mM), pH 5(1.1 mM) and pH 5.2(1.4 mM), respectively, indicating that M. acherusicum is the most sensitive species. The chronic toxicity test (population growth rate test) on $NO_3{^-}$ of B. plicatilis show that the NOEC, LOEC and $96h-EC_{50}$ are 5.9 mM, 11.8 mM and 32.6 mM, respectively, indicating that B. plicatilis is the most sensitive species. In conclusion, toxic effecst on the marine organism caused by the nitric acid spill accident is determined to be so slightly except for the most adjacent area of the ship in pH scale and such concentration of nitrate, to the extent of directly influencing the survival and reproduction of the marine organism, is determined practically not to be applicable in the typical accidents in the sea.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.11
• /
• pp.1985-1994
• /
• 2000

This research was designed to investigate the effect of initial adsorbed amount of phenol, temperature, and pH on the desorption reaction of phenol from spent activated carbon loaded with phenol. Methanol, acetone, and N,N-dimethylformamide( DMF) were used as test organic solvents. The initial adsorbed quantities of phenol investigated here were 166.1mg/g, 180.7mg/g, and 197.9mg/g. The effect of temperature was evaluated from 15 to $55^{\circ}C$ with an interval of $10^{\circ}C$, while that of pH was investigated under acidic. neutral. and alkaline conditions. The extent of phenol desorption was proportional to the strength of dipole moment such as methanol < acetone < DMF. Over 90% desorption of phenol was achieved by acetone and DMF. The quantity of des orbed phenol by the organic solvents decreases with increasing the initial adsorbed amount of phenol. DMF is affected least by the initially adsorbed amount of phenol. An increase in reaction temperature leads to higher desorption of phenol. Desorption reaction by methanol is most sensitive to the temperature. As the pH of solvents increases. the desorption rate is also increasing. At pH=12. the desorption rate of phenol by methanol increases sharply by 10%. Although methanol demonstrated the weakest desorption power. the desorption capacity of methanol would approach that of acetone and DMF by adjusting temperature and pH. Methanol may emerge as a promising solvent for removing phenol from activated carbon because of acceptable regeneration efficiency as well as relatively cheap price.

• Resources Recycling
• /
• v.30 no.6
• /
• pp.3-11
• /
• 2021

In this study, the effect of the solubility of ammonium metavanadate and the decomposition ratio of ammonium ions on a precipitation reaction-the precipitation of ammonium metavanadate by adding ammonium chloride to a sodium vanadate solution-was investigated. As the precipitation temperature and pH increased, the decomposition ratio of ammonium ions increased, and the decomposition ratio was greater than 81% at 45 ℃ and pH 9.3. This was approximately four times higher than that at pH 8. The result of the precipitation reaction, in view of these two factors that significantly influence the precipitation reaction, was that the precipitation yield increased as the temperature increased. However, the effect of temperature was not significant above 35 ℃. A kinetic study of the precipitation reaction revealed that the activation energy of the reaction was 42.3 kJ/mol. Therefore, considering the solubility of ammonium metavanadate, the lower the temperature, the better the vanadium recovery yield. Additionally, considering the decomposition of ammonium ions, the lower the pH of the aqueous solution, the more advantageous. However, at pH 8 or less, sodium polyvanadate is precipitated and the purity of vanadium oxide may reduce.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.1
• /
• pp.111-118
• /
• 2014

The present study concerns the leachability of alkali ions from hardened cement paste in terms of an increase in the pH together with the rate of alkali leaching. To evaluate the influence of mix design on the leaching capacity and rate of alkali, different water-cement ratios (W/C) and binders were used to manufacture paste specimens. The cement paste was made in the form of rectangular bucket where deionised water was subsequently supplied as solvent media. Then the specimen was wrapped in polythene film to avoid contact to atmospheric conditions, which may affect the water chemistry in the bucket. The pH of media was monitored until no further change in the pH value was observed, of which value then used to calculate the leaching capacity and rate. The influence of binder on the pH of solvent is more dominant than that of water to cement ratio: OPC paste produced the highest level of alkali leaching, whilst 30% PFA and 60% GGBS pastes imposed lower level of alkali leaching. After the monitoring of the pH, the inner bucket was ground with an increment of 1.0 mm to measure the leaching influence using the suspension consisting of paste powder and deionised water. It was found that the impact zone for OPC was about 7-8 mm, whilst 30% PFA and 60% GGBS had deeper impact depth of the alkali leaching.

• Economic and Environmental Geology
• /
• v.31 no.1
• /
• pp.11-20
• /
• 1998

The effects of the major cations ($Ca^{2+}$, $Mg^{2+}$, $K^+$, $Na^+$), complex-forming anions ($SO_4{^{2-}}$, $HCO_3{^-}$), and solution pH on the adsorption of $^{137}Cs$ and $^{90}Sr$ by kaolinite in groundwater chemistry were investigated. Three-dimensional Kd modelling designed by a statistical method was attempted to compare the relative effect among hydrated radii, charge and concentration of competing cations on the adsorption of Cs and Sr. The modelling results indicate that the hydrated radii of competing cations is the most important factor, and then their charges and concentrations are also important factors in order. The property of zeta potential of kaolinite particles was discussed in terms of the amphoteric reactions of a kaolinite surface affecting the adsorption of Cs and Sr. The ionic strength of competing cations on the adsorption of Cs and Sr exerts a greater effect than the solution pH. The sorption behaviour of Sr on kaolinite is also highly dependent on the concentration of bicarbonate. The speciation of Sr and the saturation state of a secondary phase were thermodynamically calculated by a computer program, WATEQ4F. This indicates that the change in solution pH with the concentration of bicarbonate and the precipitation of a strontianite ($SrCO_3$) are major factors controlling Sr adsorption behaviour in the presence of bicarbonate ion.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.26 no.4
• /
• pp.620-624
• /
• 1997

The conditions for color intensity and electron donating ability to $\alpha$,$\alpha$-diphenyl-$\beta$- picryl-hydrazyl (DPPH) of Bacillus subtilis DC-2 were investigated. Temperature, pH and cultivation time were chosen as three factors, and the optimal conditions of color intensity and DPPH was determined with response surface methodology. Color intensity was affected by cultivation temperature(p<0.1). DPPH was influenced by cultivation temperature(p<0.05) and pH(p<0.1). But cultivation time was affected neither color in- tensity nor DPPH. Optimal conditions of color intensity with Bacillus subtilis DC-2 were appeared at cultivation temperature of 39.$25^{\circ}C$, pH 8.83 and cultivation time of 84.41hrs. Optimal conditions of DPPH with Bacillus subtilis DC-2 were revealed at cultivation temperature of 39.19$^{\circ}C$, pH 8.84 and cultivation time of 82.21hrs.

• Korean Journal of Soil Science and Fertilizer
• /
• v.23 no.4
• /
• pp.297-301
• /
• 1990

The study was conducted to investigate the effects of diatomearth(pH 3 and CEC 20me/100g) on the adjustment of nursery soil pH and on the growth of rice seedling in the tray. The results are as follows ; 1. The soil pH and damping-off of rice seedling were decreased with increase in diatomearth application. 2. Ten to fifteen percent of diatomearth was required to adjuse the optimum soil pH range of 4.5-5.5. 3. Changes in nursery soil pH adjusted by diatomearth were less than those by sulfuric acid during the incubation period. 4. Diatomearth application increased dry weight and height of rice seedling.