• Membrane and Water Treatment
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• v.3 no.1
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• pp.63-76
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• 2012

Mother liquid discharged from a salt-manufacturing plant was electrodialyzed at 25 and $40^{\circ}C$ in a continuous process integrated with $SO_4{^{2-}}$ ion low-permeable anion-exchange membranes to remove $Na_2SO_4$ and recover NaCl in the mother liquid. Performance of electrodialysis was evaluated by measuring ion concentration in a concentrated solution, permselectivity coefficient of $SO_4{^{2-}}$ ions against $Cl^-$ ions, current efficiency, cell voltage, energy consumption to obtain one ton of NaCl and membrane pair characteristics. The permselectivity coefficient of $SO_4{^{2-}}$ ions against $Cl^-$ ions was low enough particularly at $40^{\circ}C$ and $SO_4{^{2-}}$ transport across anion-exchange membranes was prevented successfully. Applying the overall mass transport equation, $Cl^-$ ion and $SO_4{^{2-}}$ ion transport across anion-exchange membranes is evaluated. $SO_4{^{2-}}$ ion transport number is decreased due to the decrease of electro-migration of $SO_4{^{2-}}$ ions across the anion-exchange membranes. $SO_4{^{2-}}$ ion concentration in desalting cells becomes higher than that in concentration cells and $SO_4{^{2-}}$ ion diffusion is accelerated across the anion-exchange membranes from desalting cells toward concentrating cells.

• Journal of Environmental Science International
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• v.5 no.6
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• pp.739-748
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• 1996

This study was carried out to investigate the chemical characteristics ol rainwater sampled in Cheju City from July 1994 to June 1996. Concentrations of major ions (Cl-,$SO_4^{2-}$, NO_3^-$, $Na^+$, $K^+$, Ca^{2+}$, $Mg^{2+}$ and NH_4^+$) were determined. The pH of rainwater, calculated from the volume weighted H+ concentration, was found to be 5.61, indicating extensive neutralization of the acidity in the rain. The relative magnitude of average ionic concentrations followed the relation Cl-> $SO_4^{2-}$) $Na^+$> Ca^{2+}$> NH_4^+$> NO_3^-$> $Mg^{2+}$> $K^+$. The ions associated with sea salt, namely $Na^+$ and $Cl^-$, dominated the total concentration of ions in the rainwater and the $SO_4^{2-}$ ion accounts for 20% of total concentration. [H+][nss-SO42-+NO3] ratio and a multiple regression for $SO_4^{2-}$ and NO3- ions against $H^+$, $Ca^{2+}$ and $NH_4^+$ suggested that all of $SO_4^{2-}$ and $NO_3^-$ in rainwater was not necessarily associated with $H_2SO_4$ and $HNO_3$, but might also occur in combination with $NH_4^+$ or Ca^{2+}$. The monthly mean concentrations of $SO_4^{2-}$-, Ca^{2+}$ and $NH_4^+$ in spring time was higher than those in other seasons. These results may De attributed to the fertilizer application as the local sources and the yellow sand phenomina as a regional-scale sources.

• Journal of Environmental Science International
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• v.25 no.5
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• pp.727-736
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• 2016

The ambient mass concentration and chemical composition of the $PM_{2.5}$ were determined at the highland site with 1,100 m above sea level on Jeju Island from June 2013 to November 2014. Yearly averaged mass concentration of $PM_{2.5}$ was $11.97{\pm}8.63{\mu}g/m^3$. $PM_{2.5}$ concentrations were highest during the spring, while they tended to be lowest during the summer. Eight water soluble ionic species attributed 45.5% to $PM_{2.5}$ mass. $SO{_4}^{2-}$, $NO_3{^-}$ and $NH_4{^+}$ were major ions, which occupied to 27.9%, 3.7% and 12.3%, respectively. The greatest contributors to total mass concentration of water-soluble ions contained in $PM_{2.5}$ were sulfate, ammonium and nitrate. These three ions accounted for 96.6% in total ions mass concentration of $PM_{2.5}$. We could infer that these three secondary ions exist mostly in the form of $(NH_4)_2SO_4$ and $NH_4NO_3$. $Ca^{2+}$ and $Mg^{2+}$ had a good relationship and with r=0.9. The molar ratio of $Mg^{2+}/Ca^{2+}$ in this study was lower than the value observed in sea water and higher than that in soil dust, indicating that these two ions originated from other sources rather than ocean and soil dust in this study.

• The Korean Journal of Ecology
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• v.21 no.3
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• pp.195-201
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• 1998

This study was carried out to investigate characteristic of ions in rainwater by throughfall, stemflow and rainfall at air polluted area(Kure city industrial city) and non-air polluted area (Higashihiroshima city non industrial city). pH of rainwater in air polluted area were all low as compared with those in non-air polluted area. EC of rainwater in ir polluted area were high in throughfall and stemflow, but there was no difference between both areas in rainfall. The concentration of major ions in rainwater were generally high at air polluted area, especially of $Mg^{2+}$, $Ca^{2+}$, $Cl^{-}$ and $SO_4^{2-}$ in stemflow. But there was little difference in $NH_4^{+}$, and there was also cases had a high concentration in non-air polluted area. By comparison with forest type, in stemflow concentration of ions in coniferous forest were higher than those in broad-leaved, but in throughfall they were higher in mixed forest rather than coniferous forest. There was no correlation between the amount of rainwater and pH, and also EC. $NO_4^{-}$ and $SO_{4}^{2-}$ had high correlations between major ions besides $Na^{+}$ and $NH_{4}^{+}$ in air poluted area.

• Journal of Environmental Science International
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• v.24 no.6
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• pp.785-792
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• 2015

This study investigates weekday/weekend characteristics of $PM_{10}$ concentration and chemical composition of water-soluble ions in Busan in the spring of 2013. Contribution rate of water-soluble ions to PM10 concentration in weekday/weekend were 41.5% and 38.5%, respectively. Contribution rate of SO_4{^{2-}}$ to total ion mass in weekday/weekend were 30.4% and 33.8%, respectively. Contribution rate of total inorganic water-soluble ions in PM10 in weekday/weekend were 42.2% and 39.1% (mean 41.4%), respectively. $[NO_3{^-}/SO_4{^{2-}}]$ ratio in weekday/weekend were 1.01 and 0.97(mean 0.99), respectively, which indicated that weekday ratio was higher. Contribution rate of sea salts and $Cl^-/Na^+$ ratio in PM10 in weekday/weekend were 8.1% and 7.6%, 0.37% and 0.41%, respectively. This research will help understand chemical composition of water-soluble ions during the weekday/weekend and will be able to measure the contribution level of artificial anthropogenic source on urban air.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.2
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• pp.147-153
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• 1993

From March 1990 to August 1991, every each 5mm bulk precipitation samples were collected at one residental area in Taejon City to investigate chemical characteristics of acid rain. Major ion concentrations of rain samples $(pH, SO_4^{2-}, NO_3^-, CL^-, NH_4^+, Na^+, K^+, Ca^{2+}, Mg^{2+})$ were analysed and compared with the concentration of air pollutants (T. S. P, $SO_2, NO_x$) that were measured by Ministry of Environment. The results of statistical analysis are as followings. Rain pH was relatively high on October and January and relatively low on August, November and February. Major anion is sulfate, and it's concentration is 2.36 times higher than nitrate's, and major cations are ammonium, sodium and calcium ion. Monthly variation of sulfate and calcium concentrations are higher than the others. Ion concentration and rain pH were correlated negatively with rainfall amount. Major ions in rain samples were $SO_4^{2-}, NO_3^-, NH_4^+, Ca^{2+}$ and regression equations are proposed by multiple regression of measured data. Also, regression equation between air pollutants(T. S. P, $SO_2$) and $SO_4^{2-}, Na^+, K^+, Ca^{2+}, Mg^{2+} ions in rain samples were made. From this wer can predict rain pH.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.757-764
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• 2008

This paper was conducted to evaluate the durability of cement mortars exposed to varying concentrations of sodium sulfate for up to 540 days. Three types of cement mortars, namely OPC, SRC and SGC, were exposed to four sodium sulfate solutions with concentrations of 4225, 8450, 16900 and 33800 ppm of ${SO_4}^{2-}$ ions at ambient temperature. The sulfate deterioration was evaluated by measuring compressive strength and linear expansion of mortar specimens. Experimental results indicated that the maximum deterioration was noted in OPC mortar specimens in highly concentrated sulfate solution. In particular, the $C_3A$ content in cements plays a critical role in resisting expansion due to sodium sulfate attack. Additionally, the beneficial effect of GGBS was clearly observed showing a superior resistance against sodium sulfate attack, because of its lower permeability. Another important observation was that the parameters for the evaluation of deterioration degree are greatly dependent on the products formed by sulfate attack.

• Journal of Environmental Science International
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• v.25 no.5
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• pp.715-726
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• 2016

This study investigates the characteristics of metallic and ionic elements concentration, concentration according to transport path, and factor analysis in $PM_{10}$ at Guducsan in Busan in the springtime of 2015. $PM_{10}$ concentration in Guducsan and Gwaebeopdong were $59.5{\pm}9.04{\mu}g/m^3$ and $87.5{\pm}20.2{\mu}g/m^3$, respectively. Contribution rate of water-soluble ions and secondary ion in $PM_{10}$ concentration in Guducsan were 37.0% and 27.8% respectively. [$NO_3{^-}/SO{_4}^{2-}$] ratio and contribution rate of sea salt of $PM_{10}$ in Guducsan and Gwaebeopdong were 0.91 and 1.12, 7.0% and 5.3%, respectively. The results of the backward trajectory analysis indicates that $PM_{10}$ concentration, total inorganic water-soluble ions and total secondary ions were high when the air parcels moved from Sandong region in China than non-Sandong and northen China to Busan area. The results of the factor analysis at Guducsan indicates that factor 1 was anthropogenic source effects such as automobile emissions and industrial combustion processes, factor 2 was marine sources such as sea salts from sea, and factor 3 was soil component sources.

• Resources Recycling
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• v.11 no.1
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• pp.26-31
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• 2002

The recovery of $H_2$$SO_4$from sulfuric acid waste was attempted by a diffusion dialysis method using an anion extchange membrane. The effect of flow rate, temperature, concentration of metal ions on the recovery rate was studied. The recovery of $H_2$$SO_4$decreased with the concentration of $H_2$$SO_4$and flow rate. The recovery increased with the flow rate ratio of water/$H_2$$SO_4$solution upto 1 above which no further increase was observed. The flow rate did not affect the rejection of Fe and Ni ions. As a result, about 80% of $H_2$$SO_4$could be recovered from sulfuric acid wastes which contains 4.5M free$-H_2$$SO_4$at the flow rate of 0.26 $1/hr-m^2$. The concentration and purity of recovered $H_2$$SO_4$was 4.3M and 99.8%, respectively.

• Journal of Korean Society on Water Environment
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• v.34 no.1
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• pp.77-83
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• 2018

This paper aims to evaluate the results of toxicity testing with Daphnia magna and Vibrio fischeri on wastewater samples which might be influenced by ion imbalance. The effluents from factories were found to be more toxic with high salinity levels than those from public wastewater treatment plant (WTP) and sewage treatment plant (SWP). Clion composition was highest in the effluent, in terms of percentage, which was followed by $Na^+$, $SO_4^{2-}$ and $Ca^{2+}$. $K^+$ and $Mg^{2+}$ ion was relatively low. The sensitivity of D. magna test results was higher than V. fischeri. Among samples which were proved by V. fischeri testing to be nontoxic, the composition ratio of each ion whether toxic samples or nontoxic samples which were decided by D. magna toxicity testing, were compared. $Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$ ion composition ratio showed high level in nontoxic samples whereas $SO_4^{2-}$ and $Cl^-$ ion composition ratio was high in toxic samples. Accordingly, $SO_4^{2-}$ and $Cl^-$ ion seemed to be considered the ions causing toxicity in effluent. Toxicity from some categories of industries (Mining of non-metallic minerals, Manufacture of basic organic petrochemicals, Manufacture of other basic organic chemicals, Manufacture of other chemical products etc.) seemed to be influenced by salinity. The Ion concentration in influent and effluent were similar. Concentration of $Na^+$, $Cl^-$, $K^+$, $Ca^{2+}$ ions were high in influent, however $Mg^{2+}$ and $SO_4^{2-}$ ions were high in effluent.