• Macromolecular Research
• /
• v.10 no.2
• /
• pp.103-107
• /
• 2002

High purity water soluble chitosans (WsCs) were employed as a flocculant to remove heavy metal ions from wastewater of industrial plating wastewater treatment complex. Their weight average molecular weights and polydispersities were 272,000~620,000 g/mol and 1.4~1.9 range, respectively and were readily soluble in water in the pH range of 3~11. Heavy metal ions such as chromium, iron and copper were removed well by WsCs. When WsCs was blended with either sodium N, N-diethyldithiocarbamate trihydrate (SDDC$_{T}$) or sodium salicylate (SSc), the removal efficiency was further increased primarily due to the excess amount of hydrophilic sulfonic and carboxylic groups. Especially, in the case of WsCs-SSc the remaining chromium and copper concentrations were 0.1 mg/L and 9.5 mg/L, which are 1/15 and 1/3 compared with that of pure WsCs, respectively. The former is within the acceptable limit, but the latter is not. Therefore, the effective copper flocculant remains to be studied.d.

• YAKHAK HOEJI
• /
• v.60 no.2
• /
• pp.73-77
• /
• 2016

Alginic acid and carboxymethyl cellulose sodium are dietary fibers from plants. They have a swelling property and delay the gastric emptying time, thereby resulting in feeling satiated after oral administration, which may eventually contribute to loss of body weight. The goal of this study was to compare swelling property of three commercial matrix tablets based on alginic acid and carboxymethyl cellulose sodium. When the swelling was determined by the Korean Ministry of Food and Drug Safety (MFDS) guideline, the tablet prepared by direct compression method with highly viscous swelling agent showed the highest swelling in acidic conditions. Water uptake of these tablets was rapid and completed within 30 min. Moreover, when the pH was changed from 2.5 to 6.8 buffer, the water uptake was not significantly changed in all tablets.

• Korean Journal of Materials Research
• /
• v.24 no.5
• /
• pp.271-276
• /
• 2014

Silica nano-powder (SNP) is an inorganic material able to provide high-performance in various fields because of its multiple functions. Methods used to synthesize high purity SNP, include crushing silica minerals, vapor reaction of silica chloride, and a sol-gel process using TEOS and sodium silicate solution. The sol-gel process is the cheapest method for synthesis of SNP, and was used in this study. First, we investigated the shape and the size of the silica-powder particles in relation to the variation of HCl and sodium silicate concentrations. After drying, the shape of nano-silica powder differed in relation to variations in the HCl concentration. As the pH of the solution increased, so did the density of crosslinking. Initially, there was NaCl in the SNP. To increase its purity, we adopted a washing process that included centrifugation and filtration. After washing, the last of the NaCl was removed using DI water, leaving only amorphous silica powder. The purity of nano-silica powder synthesized using sodium silicate was over 99.6%.

• Korean Journal of Soil Science and Fertilizer
• /
• v.48 no.5
• /
• pp.326-331
• /
• 2015

High salinity and sodicity of soils play a negative role in producing crops in reclaimed tidal lands. To evaluate the effects of soil ameliorants on salt removal in a highly saline and sodic soil of reclaimed tidal land, we conducted a column experiment with treating gypsum, compost, and phosphate at 0-2 cm depth and measured the salt concentration of leachate and soil. Electrical conductivity of leachate was $45-48dSm^{-1}$ at 1 pore volume (PV) of water and decreased to less than $3dSm^{-1}$ at 3 PV of water. Gypsum significantly decreased SAR (sodium adsorption ratio) of leachate below 3 at 3 PV of water and soil ESP (exchangeable sodium percentage) below 3% for the whole profile of soil column. Compost significantly decreased ESP of soil at 0-5 cm depth to 5% compared with the control (20%). However, compost affected little the composition of cations below a depth of 5 cm and in leachate compared with control treatment. It was concluded that gypsum was effective in ameliorating reclaimed tidal lands at and below a soil layer receiving gypsum while compost worked only at a soil layer where compost was treated.

• Korean Journal of Veterinary Pathology
• /
• v.5 no.1
• /
• pp.23-28
• /
• 2001

This study was conducted to assess the chemopreventive effects of sodium selenite in the rat medium-term multi-organ bioassay using a DMBDD model (DEN+MNU+BBN+DMH+DHPN). Seventy five,6-week-old, male SD rats were divided into 3 groups. The animals in group 1 received DEN(diethylnitrosamine,100 mg/kg bw, single i.p., in saline), MNU (N-methyl-nitrosourea,20 mg/kg bw, i.p.,4 times for 2 weeks), BBN (N-butyl-N-(4-hydroxybutyl) nitrosamine, 0.2% in drinking water for 2 weeks), DMH (1,2-dimethylhydrazine, 40 mg/kg bw, s.c., in saline.4 times (or 2 weeds), and DHPN (N-bis(2-hydroxy-pro-pal)nitrosamine,0.1% in drinking water for 2 weeks), then were placed on sodium selenite (4 ppm in drinking water) for 22 weeks from weeks 4 to 26. The animals in group 2 were given DMBDD alone. The animals in group 3 were given sodium selenite alone. Animals were sacrificed at week 12 for ACF quantitative analysis and at week 26 for tumor induction. The body weights in the group 1 were significantly decreased compared with those of group 2. The tumor multiplicities of large intestine in the group 1 were significantly decreased compared with those of group 2 (P<0.05). These results indicate that sodium selenite may have a potential as chemopreventive agents of colon carcinogenesis.

• Journal of the Korean Ceramic Society
• /
• v.45 no.1
• /
• pp.54-59
• /
• 2008

Hydrated sodium silicate with 25 wt% water contents was synthesized by hydrothermal reaction using anhydrous sodium silicate. The hydrated sodium silicate was expanded at $370^{\circ}C$ for 30 min. and then pulverized, classified (- 200 mesh) and press-formed. The samples were heat treated at $400{\sim}900^{\circ}C$ for 30 min. in order to study the expansion characteristics depending on heat treatment temperature. A porous body with closed pore was formed above $600^{\circ}C$. The volume expansion ratio and the pore size were increased and the specific gravity was decreased with increasing heat treatment temperature. However, the volume expansion ratio was decreased and the specific gravity was increased above $850^{\circ}C$ due to the softening of the sodium silicate.

• Nuclear Engineering and Technology
• /
• v.34 no.4
• /
• pp.286-300
• /
• 2002

An algorithm for the sodium boiling model has been developed for calculation of the void reactivity feedback as well as the fuel and cladding temperatures in the KALIMER core after onset of sodium boiling. Modeling of sodium boiling in liquid metal reactors using sodium as a coolant is necessary because of phenomenon difference comparing with that observed generally in light water reactor systems. The applied model to the algorithm is the multiple-bubble slug ejection model. It allows a finite number of bubbles in a channel at any time. Voiding is assumed to result from formation of bubbies that (ill the whole cross section of the coolant channel except for the liquid film left on the cladding surface. The vapor pressure, currently, is assumed to be uniform within a bubble The present study is focused on not only demonstration of the vapor bubble behavior predicted by the developed model, but also confirmation of a qualitative acceptance for the model. As a result, the model can represent important phenomena in the sodium boiling, but it is found that further effort is also needed for its completition.

• Journal of the Korean earth science society
• /
• v.21 no.1
• /
• pp.81-92
• /
• 2000

The purpose of this study is to elucidate the characteristic of this study is of attitudinal variation of water quality for nine representative springs in the Halla mountain region. The evolutional processes of the spring water also have been studied. Results of hydrogeochemical analyses show that Gwaneumsa spring is very high in pH. The spring waters from Yungsil, Namguksunwon, Sungpanark Oremok and Gwaneumsa which springs situated lower than 1000m in altitude are relatively high concentrations in chloride, sulphate, nitrate nitrogen and sodium ions, indicating that they are affected by surrounding pollution sources. The concentrations of bicarbonate, sulphate and hydrogen ions in spring waters increase when the precipitation increases, whereas the concentrations of nitrate nitrogen, chloride and calcium ions decrease with increasing amounts of precipitation. The magnesium, sodium and electrical conductivity are nearly independent of the precipitation. The spring waters in the Halla mountain region belong to the groups of sodium or potassium type and bicarbonate type, except the Baegrogdam and Wiseorm spring water.

• Applied Chemistry for Engineering
• /
• v.5 no.4
• /
• pp.669-680
• /
• 1994

DMA-co-DAMA were synthesized from 2-diethylaminoethyl metacrylate and dodecyl-metacrylate containing long chain hydrocarbon group with hydrophilic and hydrophobic radicals. To facilitate water emulsification,acrylic copolymer was cationized by acetic acid to produce acetated acrylic copolymer. The structures of the synthesized copolymer and acetated copolymers were confirmed by IR, NMR, and molecular weight was measured by GPC, and C. H. N elemental analysis. Acetated acrylic copolymers were perfectly emulsified in water and showed increased emulsion stability. Polymer dispersion for cement modifier(PDCM-PDD) was prepared by blending of the guaternized acrylic copolymer synthesized above sodium silicate sodium gluconate oleic acid and triethanol amine. The result with prepared polymer dispersion of cement modfier was examined, and it was found that excellent waterproffing effect; Water permeability ratio is 0.44 under the water pressure of $100g/cm^2$ and 0.55 under $3kg/cm^2$, and water absorption ratio is 0.36~0.47 and 1.02 compressive strength ratio at mixed ratio of water/PDCM-PDD is 45 times.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.10a
• /
• pp.453-460
• /
• 2005

Sodium silicate - the usual portland cement which accomplishes a cement pouring reconsideration main stream and sodium silicate(No.3) after reacting sodium silicate(No.3) with the reaction sodium silicate where oxidation natrium which is included does not react with the cement receiving stiffening water it will burn together on underwater and to become the durability lacks pouring it is recognized. From the hazard which improves an advantage it used the additive which relates in congealing and stiffening of the portland cement and sodium tripolyphosphate(STPP) addition hour initial material age(72 hours at once) which does to be revealed the at high-in-tensity is discovered while accomplishing. The effect of additives on the reactions of sodium silicate solution and cement suspesion was investigated by various physical and chemical tests, such as Si-NMR, XRD, SEM uniaxial compression test. The additives were STPP(sodium tripolyphosphate), EDTA, SUGAR. The compressive strength of sodium silicate(No.3) - cement grout with additives was about $1.5{\sim}10$ times higher than that without additive in early age(72 hours).