• Resources Recycling
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• v.28 no.5
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• pp.51-59
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• 2019

This study focused on the synthesis of the nickel hydroxide using ammonium sulfate in leaching solution from waste nickel-cadmium batteries. The effect of pH, temperature and the input amount of ammonium sulfate in leaching solution was investigated. The ammonium nickel sulfate with high purity was obtained in acidic leaching solution and the solution temperature of $60^{\circ}C$. The suitable molar ratio of the input amount of ammonium sulfate to nickel in solution is 2:1. The impurity about 1.4 at.% of Cd was included in the nickel hydroxide precipitates when ammonium nickel sulfate was used. At the process using sodium sulfide which precipitates the cadmium in solution, nickel and iron compounds were precipitated together.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.4
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• pp.463-474
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• 2010

In this study, chemical coagulation conditions for treating combined sewer overflow(CSO) occurred during rainy season were evaluated by jar tests with aluminum sulfate[$Al_2(SO_4)_3{\cdot}17H_2O$] and ferric chloride[$FeCl_3{\cdot}6H_2O$]. The raw domestic sewage sampled from the primary sedimentation tank at a local sewage treatment plant was filtered through $150{\mu}m$ sieve before using. Point of zero charge(PZC) for various dose of aluminum sulfate occurred at pH 5.8-6.5, while for ferric chloride occurred at pH 5.3-6.0 in term of streaming current(SC) values. Charge neutralization ability of aluminum sulfate was bigger than that of ferric chloride. Optimum pH and dose of aluminum sulfate and ferric chloride were 6.2, 0.438mM and 5.8, 0.925mM, respectively. Removal efficiencies of TCOD, turbidity, SS and TP were 75, 97, 95, 96% with aluminum sulfate and 74, 96, 98, 99% with ferric chloride at their optimum coagulation conditions. More efficient removal of SS, TP and small particles was possible with ferric chloride at optimum coagulation conditions. Both SC values and COD removal started to increase where soluble phosphorus was completely removed.

• Journal of Integrative Natural Science
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• v.2 no.1
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• pp.24-27
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• 2009

Electrochemistry of 1.0 mM tris(2,2'-bipyridyl)ruthenium(II) ($Ru(bpy)_3{^{2+}}$) in 300 mM $H_2SO_4$ solution with and without sodium dodecyl sulfate (SDS) is studied. In the presence of SDS, $E_{pa}$ of $Ru(bpy)_3{^{2+}}$ shifts to positive direction compared to the SDS free case. The intersection of two lines on ${\Delta}E_p$ vs. -log[SDS] plot is measured as a critical micelle concentration (CMC), which is 3.67 mM SDS.

• Journal of Wetlands Research
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• v.6 no.1
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• pp.117-132
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• 2004

Despite its significance in understanding ecological structure and biogeochemical element cycles, there have been few studies on the microbial mineralization of organic matter and mineralization pathway in the intertidal flat of Korea. We measured anaerobic mineralization of organic matter and sulfate reduction rate, and evaluated the significance of sulfate reduction in total anaerobic carbon respiration at the southern part of Ganghwa Island. Depth-integrated carbon mineralization rate down to 6 cm depth ranged from 41.9 to $89.4mmol\;m^{-2}d^{-1}$, which accounted for approximately 216 tons of organic matter mineralization in entire intertidal flat area of Ganghwa($300km^2$). The results indicated that capacity for the organic matter mineralization in the Ganghwa tidal flat is comparable to highly productive salt marsh environments. Mineralization rates in the sediment amended with acetate were 2~5 times higher than in unamended sediment. The results implied that microbial mineralization was limited by the availability of organic substrates, and the organic matter mineralization capacity seems to be higher than estimated at ambient organic substrate level. Depth-integrated sulfate reduction rates within 6 cm depth of the sediment ranged from 20.7 to $45.1mmol\;SO{_4}^{2-}m^{-2}d^{-1}$, and sulfate reduction was mostly responsible for organic matter remineralization. It should be noticed that the increase of $H_2S$ in the sulfate reduction dominated tidal flat may result in the decrease of biological diversity.

• Elastomers and Composites
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• v.53 no.2
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• pp.75-79
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• 2018

ZnS:Mn-glycine (ZnS:Mn-Gly) nanocomposites were synthesized by capping ZnS:Mn nanocomposites with glycine. Zinc sulfate heptahydrate ($ZnSO_4{\cdot}7H_2O$), glycine ($C_2H_5NO_2$), manganese sulfate monohydrate ($MnSO_4{\cdot}H_2O$), and sodium sulfide ($Na_2S$) were used as the source reagents. $ZnS:Mn-Gly-C_{60}$ nanocomposites were obtained by heating the ZnS:Mn-Gly nanocomposites and fullerene ($C_{60}$) at a 2:1 mass ratio in an electric furnace at $700^{\circ}C$ for 2 h. X-ray diffraction (XRD) was used to characterize the crystal structure of the synthesized nanocomposites. The photocatalytic activity of the $ZnS:Mn-Gly-C_{60}$ nanocomposites was evaluated, via the degradation of brilliant green (BG) dye under 254 nm irradiation, with a UV-vis spectrophotometer.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.353-354
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• 2003

대기 중에서 여러 과정을 통해 아황산가스 (SO$_2$)가 황산 (H$_2$SO$_4$)으로 산화된다. 황산은 증기압이 낮아 대기 중에서는 대부분 황산염 (SO$_4$$^{2-}$ ) 에어로졸로 존재한다. 황산염 에어로졸은 직간접적으로 지구복사평형에 관여하여 기후와 기상에 영향을 미친다. 이 연구의 목적은 수도권에서의 아황산가스가 황산염으로 전환되는 각각의 경로의 상대적 기여도를 예측해보고자 하였으며 아황산가스에 의해 황산염이 얼마나 형성되는지를 알아보고자 하였다. (중략)

• Membrane and Water Treatment
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• v.9 no.1
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• pp.9-15
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• 2018

Coagulation process using aluminum sulfate ($Al_2(SO_4)_3$) and ferric chloride ($FeCl_3$) was employed as a treatment method for decolorization of a synthetic textile wastewater containing red dye in this paper. Factors such as initial pH, coagulant dosage, initial concentration, conductivity and mixing conditions that influence color removal efficiency were experimentally tested. It was found that $Al_2(SO_4)_3$ is more efficient than $FeCl_3$ as coagulant. When $40mgL^{-1}$ aluminum sulfate was used, results showed that color induced by the red dye was efficiently removed (> 90 %) and was obtained in a large range of initial pH from 4 to 8 with, and for a dye concentration lower than $235mg\;L^{-1}$. After addition of the coagulant, the medium had to be mixed for 30 min at 60 rpm, then allowed to settle for 40 min. The effects of water conductivity in the range $0.035-2.42mS\;cm^{-1}$ and dye concentration up to $380mg\;L^{-1}$ were also followed and discussed.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.183-189
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• 2022

This study seeks towards an optimal way to control sulfate ions in semiconductor wastewater effluent with potential eco-toxicity. We developed a system based on ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O). The basic idea is that the pH of the water is raised to approximately 12 with Ca(OH)₂. After, aluminium salt is added, leading to the precipitation of ettringite. Lab-scale batch and continuous experiment results with real semiconductor wastewater demonstrated that 1.5 and 1 of stoichiometric quantities for Ca²⁺ and A³⁺ with pH above 12.7 could be considered as the optimal operation condition with 15% of sludge recycle to the influent. A mixed AlCl₃ + Fe reagent was selected as the beneficial Al³⁺ source in ettringite process, which resulted in 80% of sludge volume reduction and improved sludge dewaterability. The results of continuous experiment showed that with precipitation as ettringite, sulfate concentration can be stably reduced to less than 50 mg/L in effluent from the influent 2,050 ± 175 mg/L on average (1,705 ~ 2,633 mg/L).

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1749-1756
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• 2005

The $NiSO_4$ supported on FeO-promoted $ZrO_2$ catalysts were prepared by the impregnation method. FeOpromoted $ZrO_2$ was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and iron nitrate solution followed by adding an aqueous ammonia solution. The addition of nickel sulfate (or FeO) to $ZrO_2$ shifted the phase transition of $ZrO_2$ (from amorphous to tetragonal) to higher temperatures because of the interaction between nickel sulfate (or FeO) and $ZrO_2$. 10-$NiSO_4$/5-FeO-$ZrO_2$ containing 10 wt % $NiSO_4$ and 5 mol % FeO, and calcined at 500 ${^{\circ}C}$ exhibited a maximum catalytic activity for ethylene dimerization. $NiSO_4$/FeO-$ZrO_2$ catalysts was very effective for ethylene dimerization even at room temperature, but FeO-$ZrO_2$ without $NiSO_4$ did not exhibit any catalytic activity at all. The catalytic activities were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The addition of FeO up to 5 mol % enhanced the acidity, surface area, thermal property, and catalytic activities of catalysts gradually, due to the interaction between FeO and $ZrO_2$ and due to consequent formation of Fe-O-Zr bond.

• Polymer(Korea)
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• v.27 no.1
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• pp.69-74
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• 2003

In this study, we have investigated the adsorption properties for nitrate ion in ground water using mixed resin type hybrid ion exchange (HIXF) and fiber type ion exchanger. Their swelling ratio (4.45 g/g) and ion exchange capacities (2.45 meq/g) were higer than the swelling ratio of IEC and IXF. Adsorption yield increased for nitrate $NO_3^-$ and sulfate $SO_4^{2-}$ ions were optimal at the concentration ratios of nitrate and sulfate below 1.0 and the adsorption yields were 100% and 20%, respectively. On the other hand it was shown that the degree of adsorpted for nitrate to pH 3, but it was little changed in the other pH range. We found that the selective adsorption capacity for nitrate was the optimal the mixing ratios of resin and fibrous ion exchanger of below 0.5.