• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.5
• /
• pp.353-357
• /
• 2010

Recently, silicon etching have received much attention for display industry, nano imprint technology, silicon photonics, and MEMS application. After the etching process, removing of etch mask and residue of sidewall is very important. The investigation of the etched mask removing was carried out by using the ashing, HF dipping and acid cleaning process. Experiment shows that oxygen component of reactive gas and photoresist react with silicon and converting them into the mask fence. It is very difficult to remove by using ashing or acid cleaning process because mask fence consisted of Si and O compounds. However, dilute HF dipping is very effective process for SiOx layer removing. Finally, we found optimized condition for etched mask removing.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.40 no.4
• /
• pp.43-50
• /
• 2008

Adsorption of xylans extracted from birchwood and oat spelt on Hw-BKP were analyzed using HPLC. The effect of xylan adsorption on paper properties such as tensile, tear index and brightness was also investigated. The constituents of xylan was analyzed with HPLC after hydrolysis with dilute sulfuric acid. It was shown that xylose was the major constituent and small amounts of glucose and galactose were contained in the xylan samples. Adsorption of xylan on hardwood fibers was evaluated using acid hydrolysis and HPLC techniques. Results showed that the adsorption of negatively charged xylan on the fiber surface was negligible probably because electrostatic repulsion between these two materials. Pretreatment of the fiber with alum increased xylan adsorption. The amount of adsorption increased up to 30 mg/g. With the increase of xylan adsorption both tensile and tear strength of the handsheet increased suggesting xylan can be a very effective strength agents for papermaking. Brightness of the handsheets decreased, however, with the use of xylan.

• Textile Coloration and Finishing
• /
• v.5 no.4
• /
• pp.42-48
• /
• 1993

In the present work, decoloring of acid dye solution by the diethylaminoethylated cellulosic adsorbents($CA_{DASE}$) was studied with the aim of developing polymeric adsorbents for the treatment of colored wastewaters. To prepare the cellulosic adsorbents, the $CA_{DASE}$ cellulose and polyvinyl alcohol mixture(80 wt% cellulose content) were crosslinked by tryacryloyl hexahydro-s-tryazine(TAHHT), ammonium phosphate and then treated with solutions containing sodium hydroxide and 2-diethylaminoethyl chloride. Batch and flow method were employed to determine decoloring capacity of C $A_{DEAE}$ for C.I.acid yellow 49. $CA_{DASE}$ exhibited much better desorption capacity than activated carbon. Furthermore, the exhausted $$CA{DASE} could be readily regenerated by washing with dilute sodium hydroxide.

• Journal of the Korean Chemical Society
• /
• v.16 no.6
• /
• pp.354-360
• /
• 1972

Formation of the complexes of barium, strontium and calcium ions with dibasic organic acid ions in dilute solution was studied at room temperature, utilizing the equilibrium exchange technique which involved the uses of radioactive alkaline earth metal ions and cation excbange resin. The organic acids used in this study were succinic and tartaric acids, and the solvents used were water, 20 % acetone-water and 20 % ethanol-water. The pH of the solutions was controlled to 7.2∼7.4, and the ionic strength of the solutions was kept at approximately 0.1. The experimental results indicated that the alkaline earths formed one-to-one complexes in solution with the dibasic acids examined, and that the relative stabilities of the complexes increased in the order: $Ba^{++}; succinic

• Carbon letters
• /
• v.8 no.2
• /
• pp.101-107
• /
• 2007

Activated carbons were prepared by impregnation of crushed clean date pits in concentrated solutions of phosphoric acid or zinc chloride followed by carbonization in absence of air at $600^{\circ}C$. Steam-activated carbon was prepared by gasifying $600^{\circ}C$-carbonization product at $950^{\circ}C$ to a burn-off = 50%. KOH- activated carbon was prepared by impregnating date pitscarbonization product obtained at $450^{\circ}C$ in concentrated KOH solution followed by carbonization at $840^{\circ}C$. Textural properties of these carbons were determined from nitrogen adsorption at $-196^{\circ}C$ and the chemistry of the carbon surface was investigated by determination and of the surface carbon-oxygen (C-O) groups using bases of variable strength and dilute HCl. The adsorption of endosulphan at $27^{\circ}C$ on all the carbons prepared was undertaken. Adsorption of this pesticide at 32 and $37^{\circ}C$ was also undertaken for steam-activated and KOH-activated carbons. Phosphoric acid-activated carbons and steamactivated carbons are mainly microporous and have high surface concentration of C-O groups of acidic nature. Steamactivated and KOH-activated carbons exhibited surface areas > 1000 $m^2/g$ and contain micro and non-micrpores. The adsorption of endosulphan was related to the surface area of non-micropores and was retarded by the high concentration of surface C-O groups. The thermodynamic properties indicated the feasibility of the adsorption process and the possible regeneration of the carbon for further use.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.489-490
• /
• 2006

Branched sulfonated poly(ether sulfone-ketone) copolymer was prepared with bisphenol A, 4,4-difluorobenzophenone, sulfonated chlorophenyl sulfone (40mole% of bisphenol A) and THPE (1,1,1-tris-p-hydroxyphenylethane). THPE was used 0.4 mol% of bisphenol A to synthesize branched copolymers. Organic-inorganic nano composite membranes were prepared with copolymer and a series of $SiO_2$ nanoparticles (20 nm, 4, 7 and 10 wt%). The composite membranes were cast from dimethylsulfoxide solutions. The films were converted from the salt to acid forms with dilute hydrochloric acid. The membranes were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. Branched copolymer and nano composite membranes exhibit proton conductivities from $1.12{\times}10^{-3}$ to $6.04{\times}10^{-3}\;S/cm^2$, water uptake from 52.9 to 62.4%, IEC from 0.81 to 1.21 meq/g and methanol diffusion coefficients from $1.2{\times}10^{-7}$ to $1.5{\times}10^{-7}\;cm^2/S$.

• Journal of Environmental Health Sciences
• /
• v.24 no.3
• /
• pp.11-17
• /
• 1998

Chitin is known as biodegradable natural polymer. In spite of various application of chitin derivatives from waste marine sources, commercial use of chitin has been limited due to high resistance to chemicals and the absense of proper solvents. We chitin prepared through the decalcification, bleaching and deproteination from Protunus trituberculatus shells by change of Hackman's method. Also, Microcrystalline chitin made by hydrolysis that was reduce made of resistance solvents used by dilute hydrochloric acid, ultrasonic and hydrogen peroxide. Crosslinked chitin derivatives were preparaed from chitin with crosslink agents(epichlorohydrin, 1,3-dichloropropanol) follwed by crosslinkage at 6C position. The effects of these parameters on chitin dervatives were invastigated by IR, DSC, XRD, BET, PSA and SEM. SEM analysis showed that both chitin and crosslinked chitin had a particle shaped morphology.

• Textile Coloration and Finishing
• /
• v.4 no.3
• /
• pp.131-135
• /
• 1992

Quaternary aminized cellulosic adsorbents (C $A_{QA}$ ) which exhibit adsorption capacities for anionic dyestuffs for the treatment of colored waste water and re-use of the treated water were studied. The isotherms and thermodynamic parameters of C.I. Acid Orange 7, solution considered as a model of negatively charged coloring matters for C $A_{QA}$ , were determined. Batch method and flow method were employed to determine decoloring capacity of cellulosic adsorbents for Orange 7. The cellulosic adsorbents exhibited much better adsorption capacity than activated carbon. Furthermore the exhausted cellulosic adsorbents could be readily regenerated by washing with dilute sodium hydroxide.

• Journal of Pharmaceutical Investigation
• /
• v.29 no.1
• /
• pp.1-5
• /
• 1999

The bioavailabilities of baicalin in water, oil, w/o and o/w emulsion were evaluated in rats. The dissolution rate of baicalin in o/w emulsion was smaller than those of w/o form in dilute hydrochloric acid solution (pH 1.2) and in PBS (pH 6.8). The absorption rate of baicalin from w/o emulsion was smaller than that of o/w emulsion in the different parts of rat intestine of the rats. Following oral administration in rats, the $C_{max}$ of baicalin from water phase, oil phase, o/w wand w/o emulsion were 2.11, 0.61, 1.57, and $1.35\;{\mu}g/ml$, respectively. The relative bioavailability of w/o emusion was 129 % when it was compared with water phase. This result suggests that the improvement of bioavailability for baicalin in w/o emulsion might be practically available.

• Journal of the Korean institute of surface engineering
• /
• v.30 no.1
• /
• pp.44-56
• /
• 1997

Influence of electrochemical etching conditions on capacitance gain of aluminium electrolytic on capacitor foil has been investigated by etching cubic textured high purity aluminum foil in dilute hydrochloric acid. Uniformly distributed etch pit tunnels on aluminum surface have been obtained by pretreatment aluminium foil in 10% NaOH solution for 5 minutes followed by electrochemical etching. Electrostatic capacitance of etched aluminium foil anodized to high voltage increased with the increase of current density, total charge, temperature and concentration of electrolyte up to maximum CV-value and then deceased. Election optical observation of the etched foil revealed that the density of etch of etch pits increased with the increase of current density and concentration of electrolyte. this increase of etch pit density enlarged of the increase of capacitance. However, abnormal high current density and high electrolyte concentration induced the local dissolution of the foil surface which resulted the decrease of foil capacitance.