• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.8
• /
• pp.7-15
• /
• 2002

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.821-826
• /
• 2003

Laboratory experiments were peformed to understand physical properties of soil-cement column under the influence of acidic flow including metal contaminants and its retaining capacity against metal migration. The contaminant used in this study was nitric acid with Cu and Cd. The Permeability of soil-cement column decreased when pH of the column began to drop below 12. Decreases in pH led to significant reduction of compressive strength of clayey soil-cement specimen, while relatively marginal reduction for sandy soil-cement specimen. The metal contaminants did not leachate from soil-cement column until pH of soil-cement dropped below 7∼8 for Cu and 9∼10 for Cd. Metal contaminants were precipitated and trapped inside the soil-cement column at pHs higher than those mentioned as verified with metal analysis and visual inspection. This indicated that soil-cement column not only performs well as a cut-off wall, but also helps alleviating the level of contamination of the surrounding environment.

• Resources Recycling
• /
• v.7 no.1
• /
• pp.41-49
• /
• 1998

This papcr covcrs ihe recovery process of aluminum coagulant by acidic exlraclion which can develop the dewaterability'of residual sludge solids and ihc reduclion ot sludge valumc and mass. Simultmeously, variables affecting acidic extaction of aluminum arc discussed It is represented that the characteristics of recovcrcd coagulant is assessed mth rcspcct to aluminum content. coagulalion effeaiveness, and trace contaminants. The treatment methods of residual sludge solid following acidic extraction arc also d~scussed. Fillally, we suggest some cases in which the results from laboratory can he applied to the fullscale operation and future domestic mosoect of it.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.37 no.3
• /
• pp.17-22
• /
• 2005

The cleaning efficiency of papermaking felt which is contaminated with fiber fines and various micro-materials was investigated and compared between the application of enzyme and commercial detergent. It was found that the cleaning efficiency by the treatment of acidic-based detergent was more efficient than that of alkaline-based one in the conventional commercial detergent. it was also observed that the treatment design of first acidic-based detergent treatment to second alkaline-based detergent procedure was better in the cleaning efficiency, compared to alkaline based-to-acidic based one. The cleaning property of felt with enzyme was resulted in good cleaning efficiency, without any addition of surfactant. Especially, the enzyme treatment under alkaline condition (pH 10) showed a better cleaning result than that under acidic condition(pH 5). The addition of nonionic surfactant to the enzyme increased the cleaning efficiency of felt and decreased the cationic demand of wastewater. These results showed more favour than the application of conventional commercial detergent.

• Journal of the Korean Society of Tobacco Science
• /
• v.25 no.2
• /
• pp.111-119
• /
• 2003

In this work, Rayon-based activated carbon fiber(KF-1500) was treated by HN $O_3$ and $H_2$S $O_4$ with different conditions. Specific surface areas(SSA, $S_{BET}$) of the treated activated carbon fibers were decreased by acidic treatment but, total surface acidities and surface functional groups were increased. In spite of the decrease of SSA, propylamin(PPA) adsorption and removal ability by activated carbon fiber(ACF) were increased by nitric acid treatment compared with the raw-ACF(KF-1500) and coconut based activated carbon. However, acidic treated activated carbon fibers were available to removal for various amines and contaminants by adsorption.n.

• Corrosion Science and Technology
• /
• v.20 no.4
• /
• pp.204-209
• /
• 2021

Corrosion failure analysis of the flow plate, which is one of the accessories of the plate heat exchanger in a district heating system, was performed. The flow plate is made of 316 stainless steel, and water at different temperatures in the flow plate exchanges heat in a non-contact manner. The flow plate samples in which water mixing issues occurred were collected. Corrosion-induced pits, oxides, and contaminants were observed at locations where two plates are regularly in contact. The EDS analysis of the surface oxides and contaminants revealed that they were composed of carbon, silicon, and magnesium, which came from chemical adhesives. The IC/ICP analyses showed that the concentration of chloride ions was 30 ~ 40 ppm, which was not sufficient to cause corrosion of stainless steel. In the crevice, a local decrease in dissolved oxygen occurs along with an increase in chloride ions, thus forming an acidic environment. These environments destroyed the passive film of stainless steel, resulting in pits. Moreover, contaminants formed a narrower gap between the two metal plates and inhibited the diffusion of ions, thereby accelerating crevice corrosion.

• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.6
• /
• pp.499-505
• /
• 2018

We applied column experiments to investigate the environmental fate and transport of silver nanoparticles(AgNPs) in fully saturated conditions of porous media. These column experiments were performed to emphasize oxidation method with $H_2O_2$ concentration and acidic conditions. The mobility of AgNPs was decreased with the increasing ionic strength that the surface charge of AgNPs(zeta potential) was neutralized with the presence of positive ions of $Na^+$. Additionally, it was also affected due to that not only more increased aggregated size of AgNPs and surface charge of quartz sand. The decreased breakthrough curves(BTCs) of bisphenol-A(BPA) and $17{\alpha}$-ethynylestradiol(EE2) were removed approximately 35.3 and 40%. This is due to that endocrine disrupting chemicals(EDCs) were removed with the release of $OH{\cdot}$ radicals by the fenton-like mechanisms from acidic and fenton-like reagent presenting. This results considered that higher input AgNPs with acidic conditions is proved to realistic in-situ oxidation method. Overall, it should be emphasized that a set of column experiments employed with adjusting pH and $H_2O_2$ concentration in proved to be effective method having potential ability of in-situ degradation for removing organic contaminants such as BPA and EE2.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.239-242
• /
• 2004

Pilot-scale soil washing facility was developed and operation condition was determined in order to remediate a soil contaminated with As, Ni and Zn. Soil washing facility is composed of soil particle separation, soil washing and wastewater treatment process. Both oxyanionic As and cationic Ni and Zn were effciently removed using HCl rather 0than H$_2$SO$_4$ and H$_2$PO$_4$. This is why oxyanion and cation metals can be extracted simultaneously from the contaminated soil in acidic solution. Further, the contaminated soils include calcite and then demand much acidity, that is consumption of acid solution. Fine particles are enriched with contaminants, and coarse particles are removed effectively rather than fine particles. As, Ni and Zn are strongly associated with minerals, and then the residence time should be increased for a reaction with washing solution.

• Journal of Soil and Groundwater Environment
• /
• v.13 no.3
• /
• pp.52-58
• /
• 2008

Mn-impregnated activated carbon (Mn-AC) prepared at different conditions was applied in the treatment of synthetic wastewater containing both organic and inorganic contaminants. Phenol and As(III) was used as the representative organic and inorganic contaminants, respectively. After evaluation of the physicochemical characteristic and stability of Mn-AC, oxidation of As(III) as well as adsorption of phenol by activated carbon(AC) and Mn-AC were investigated in a batch reactor. To investigate the stability of Mn-AC, dissolution of Mn from each Mn-AC was measured pH ranging from 2 to 4. Although Mn-AC was unstable at a strong acidic condition, the dissoluted Mn was below 3 ppm at pH 4. XRD analysis of Mn-AC indicated that the mineral type of the impregnated manganese was $Mn_2O_3$. From the simultaneous treatment of As(III) and phenol by AC and Mn-AC, As(III) oxidation by Mn-AC was greater than that by AC at lower pH, while the reverse order was observed at higher pH. After impregnation of Mn onto AC, 13% decrease of the surface area was observed, causing 8% reduction of phenol removal. Considering removal properties of As(III) and phenol, Mn-AC could be applied in the simultaneous treatment of wastewater contaminated with multi-contaminants.

• Journal of the Korean Applied Science and Technology
• /
• v.21 no.3
• /
• pp.252-258
• /
• 2004

This study was performed to evaluate characteristic of acid mine drainages (AMD) from abandoned mines in Kangwon-Do. Youngdong abandoned mine, and Soo and Hambaek abandoned mines in Hamtae were selected for this study. Average pHs of the mine drainages were 3-6.5, and those of Youngdong and Hambaek drainages were very acidic as 3-4. $SO_4^{-2}$ of Youngdong and Hambaek drainages were over 1,600 mg/L, which higher than average value (845 mg/L) of acid mine drainages in nationwide. Cu, Mn, and As concentrations of the drainages were lower than ‘Pollutant Discharge Permission'. Fe concentrations of Youngdong and Hambaek drainages were approximately 96 mg/L, which were two times higher than average value in nationwide. From correlation analysis using SPSS, significant correlation was not discovered between 'contaminants' analyzed in three acid mine drainages.