• Journal of the Korean Ceramic Society
• /
• v.37 no.7
• /
• pp.700-704
• /
• 2000

Titanium hydroxide precipitate was obtained by the reaction of 0.5M TiOCl2 and 5M NH4OH solutions, then anatase TiO2 powder with nanotubes was prepared by the digestion of the heat-treated powder in 5M NaOH solution. Nanotube was formed for anatase TiO2 powder digested at 10$0^{\circ}C$ above, and the amount and length of nanotube increased with the digestion temperature. In the case of the powder digested at 15$0^{\circ}C$ for 12h, the formed nanotube was 100~150nm in length, 10~20 nm in diameter, and 2nm in width of the walls on both sides of the nanotube. The powder digested at 15$0^{\circ}C$ for 12h showed the highest specific surface area of 270$m^2$/g.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.24 no.4
• /
• pp.95-103
• /
• 2016

The objective of this study was to investigate feasibility of semi-dry anaerobic digestion using dairy cattle manure and to evaluate solidified fuel value of semi-dry anaerobic digestate. To evaluate semi-dry anaerobic digestion using dairy cattle manure, 950 mL bottle type anaerobic reactor was set in the constant temperature room maintained at $35^{\circ}C$. To produce anaerobic digestate for making solidified fuel, acrylic cylindrical anaerobic digester(1,000 mm width ${\times}$ 450 mm height) was set in the constant room temperature to carry out batch test of semi-dry anaerobic digestion using same dairy cattle manure. Moisture content of dairy cattle manure and inoculum solution for anaerobic digestion were 80.64% and 96.83%, respectively. The dairy cattle manure and the inoculum solution was mixed by 1:1 ratio(v/v) for anaerobic digestion. Water content and VS/TS(Volatile Solids/Total Solids) of mixture of substrate and inoculum were 89.74% and 83.35%, respectively. In case of non-inoculated anaerobic digester, the biogas was not produced. By the semi-dry anaerobic digestion, the calorific value of the digestate was reduced by 20% compare to fresh dairy cattle manure. In other hand, ash content increased from 15% to 18.4%. The contents of Cr, Pb, Cd and S of pellet produced from anaerobically digested dairy cattle manure were not against the standard regulation for livestock manure solidified fuel. Therefore, it can be used as fuel that anaerobic digestate produced after semi-dry anaerobic digestion using dairy cattle manure.

• Journal of the Korean Chemical Society
• /
• v.23 no.3
• /
• pp.136-140
• /
• 1979

The purpose of this investigation was to study the sulfuric acid digestion of monazite sand, and to prepare rare-earths-thorium containing material from the resulting solution which would be suitable for further preparation of thorium and rare earth elements by ion-exchange. Digestion of crude monazite sand was treated in $95{\%}C$ sulfuric acid for 2.0 hours at 150∼$250^{\circ}C$. The acid to sand weight ratio were 1 : 1.9∼2.8. Optimum condition was 95% sulfuric acid for 2.0 hours at $200{\pm}5^{\circ}C$. Within this conditions monazite sand was decomposed up to 99%.

• Preventive Nutrition and Food Science
• /
• v.22 no.2
• /
• pp.107-117
• /
• 2017

The purpose of this study was to evaluate the antioxidant and anticholinesterase activities of yellow and white bitter yams from South Western Nigeria using methanolic extraction and simulated gastrointestinal digestion models. The phenolic compounds in the bitter yam varieties were evaluated by high performance liquid chromatography with a diode array detector (HPLC-DAD). The total phenolic content of the bitter yams was measured by the Folin-Ciocalteu method, reductive potential by assessing the ability of the bitter yam to reduce $FeCl_3$ solution, and the antioxidant activities were determined by the 2,2-diphenyl-1-picrylhydrazyl radical ($DPPH^{\cdot}$) scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation ($ABTS^{{\cdot}+}$) scavenging activity, nitric oxide radical ($NO^{\cdot}$) scavenging ability, hydroxyl radical scavenging ability, and ability to inhibit $Fe^{2+}$-induced lipid oxidation. The HPLC-DAD analysis revealed the presence of some phenolic compounds in the studied bitter yam varieties, with varying degree of quantitative changes after cooking. The antioxidant indices (total phenolic content, total flavonoid content, reducing power, $DPPH^{\cdot}$ scavenging activity, $ABTS^{{\cdot}+}$ scavenging activity, and $NO^{\cdot}$ scavenging activity) were higher in the simulated gastrointestinal digestion model compared to the methanolic extract, with the in vitro digested cooked white bitter yam ranking higher. Similarly, the in vitro digested yams had a higher inhibitory action against lipid oxidation compared to the methanolic extracts, with the cooked white bitter yam ranking high. The methanolic extracts and in vitro enzyme digests showed no acetylcholinesterase inhibitory abilities, while methanolic extracts and the in vitro enzyme digest displayed some level of butyrylcholinesterase inhibitory activities. Therefore the studied bitter yams could be considered as possible health supplements.

• Journal of the Korean GEO-environmental Society
• /
• v.15 no.9
• /
• pp.13-18
• /
• 2014

BMP test was carried out to evaluate the characteristics for co-digestion of night soil and food waste. 6 types of sludge were tested in 30 days which were raw, excess, digested, night soil/septic tank (1:1), food waste (food : dilution water = 1:1), and mixed sludge. Bio gas was produced actively after 2 days, and continued in 2 weeks. Gas generation amount was decreased rapidly after considerable space of time. Especially maximum productivity of gas was shown in 7~8 days. The ultimate methane yields of raw, excess, digested, night soil/septic tank, food waste, and mixed sludge were 64.63, 67.49, 66.45, 72.44, 107.85, and 46.71 mL $CH_4/g$ VS respectively from Modified Gompertz model. The lag growth phase time and maximum specific methane production rate of mixed sludge were 1.88 day and 80.4 mL/day respectively. The methane potential of mixed sludge was higher than individual sludge. So high methane potential was expected by controlling mixing ratio of food waste. Besides stable operation of digestion tank and the solution of oligotrophic problem were possible.

• Applied Biological Chemistry
• /
• v.13 no.1
• /
• pp.29-34
• /
• 1970

In order to prepare digested Protein source for the Weanling Food from soybean, an attempt was made to decompose steamed soybean protein to amino acids and peptides by protease and cellulase produced from Aspergillus niger and Aspergillus sojae. In this paper, the optimum condition for digestion of soybean protein were studied and also investigated the effects of decolorization of it. As the results, followings were obtained; 1. As steaming conditions, a treatment under 15 lb of pressure and 10 minutes of heating shows most effective. 2. The optimum pH of Asp, sojae enzyme for the digestion of soybean protein is 6.0, while that of Asp. niger enzyme is 4.4. In successievly-decomposing with Asp. sojae and Asp. niger, it shows the most effective on ratio of water-soluble-nitrogen to total nitrogen and amino-nitrogen to total nitrogen than any other separate treatments. 3. The suitable amount of the enzyme solution to that of the soybean substrate paste, in volume, is 1 : 2. 4. Digestion ratio of soybean protein indicates the gradual and steady effects of increasing time of digestion, but 8 hour-digestion regarding to putrefaction was suitable. 5. The most effective decolorization was successively passed on culumns of active carbon and anion exchanger (Dowex 2-x-8) at room temperature. In separate treatments, the effective order of decolorization was as follows; (Dowex 2-x-8)>Active carborn>Amberite IR-120 6. The powder type of the soy protein source obtained by concentration below $60^{\circ}C$ contains 12.51% of moisture, 66.31% of protein, 4.25% of fat, 12.75% of carbohydrate, 4.18% of ash.

• The Journal of the Petrological Society of Korea
• /
• v.25 no.2
• /
• pp.107-119
• /
• 2016

Trace element abundances in the igneous rocks are important data for petrogenetic interpretation. Their concentrations are generally measured using ICP-MS from the dissolved solution. The acid digestion of rock powder can be performed by conventional teflon vial or pressure bomb. In this paper, we investigated a problem that happened during acid digestion experiment using conventional teflon vial or pressure bomb of BCR2 and GSP2 USGS rock standard materials. The results show that the measured concentrations of the elements like Cr, Ni, Zn, Ta, W in the BCR2 are different from the recommended values of USGS whereas those of the elements like Rb, Sr, Zr, Hf, Ta, W in the GSP2 are different from those values. Our experiment shows that defect of specific elements like Cr, Ni may happen during the sample digestion. Our results also indicate that the Cr, Ni, W, Zr, Hf, Ta concentration obtained based on an acid digestion of geological samples need to be careful in their geochemical interpretation.

• KSBB Journal
• /
• v.16 no.4
• /
• pp.389-397
• /
• 2001

The effect of sludge digestion on the leaching efficiency of heavy metals from sludge by bioleaching with Thiobacillus thiooxidans MET was investigated. The used sludges were a non- and anaerobically digested. The leaching efficiency of heavy metals was strongly dependent on the pH of the sludge solution rather than the sludge condition and stolid concentration. The lower the pH the more heavy metal was leached from 3.0 of pH. The sequent orders of leaching heavy metals were Zn, Cu, and Cr. Although the buffering capacity of non-digested sludge was similar to anaerobically digested sludge, the pH decrease rate of the anaerobically digested sludge solution was faster than that of the non-digested sludge solution due to the higher sulfur oxidation rate of T. thiooxidans MET in the anaerobically digested sludge. The amount of leached heavy metals from the anaerobically digested sludge showed higher than that of non-digested sludge at the same pH value. This result might be caused by the difference of the insoluble metal types, which were contained in the sludge. An increase in sludge solids concentration decreased the leaching efficiency of heavy metals in the range of solids concentration 10 g/L to 70 g/L. The optimum ratio of S° to sludge stolid was 0.1 in both the sludge. The bioleaching process of heavy metals with T. thiooxidans MET showed the disinfecting effect over 90% as well as the reduction effect in sludge weight of 20%.

• The Korean Journal of Mycology
• /
• v.14 no.2
• /
• pp.165-174
• /
• 1986

Conditions for production, fusion and reversion of protoplasts of Aspergillus niger were investigated, and an attempt was made to enhance fusion frequency. Auxotrophic mutants and morphological mutants were induced by U.V. irradiation $(9.9\;erg/mm^2,\;13min)$ on Aspergillus niger. Maximum yield of protoplasts was obtained from 21 hr cultured mycelia by using 1% driselase in 0.6 M KCl or 0.6 M $NH_4Cl$ as osmotic stabilizer. The optimal temperature for mycelium digestion was $30^{\circ}C$, and the optimal pH was 6.0. Protoplasts produced at different digestion period showed heterogeneity in size and vacuole content. Maximal frequency of protoplasts reversion was obtained on 0.6 M KCl stabilized agar medium at pH 5.0. Reversion frequencies of protoplasts produced for 3 hr and 1 hr mycelial digestion were 8.0% and 15.3%, respectively. The optimal concentration of PEG(m.w. 6000) for protoplast fusion was 30%, and that of $CaCl_2$ was $1{\sim}50\;mM$. The optimal pH and period for the reaction of PEG solution were 8.0 and 10 minutes, respectively. Fusion frequencies between auxotrophic protoplasts produced for 3 hr-mycelial digestion were $0.06{\sim}0.42%$, and those for 1 hr-mycelial digestion were $0.09{\sim}0.54%$.

• Analytical Science and Technology
• /
• v.23 no.6
• /
• pp.511-517
• /
• 2010

Dissolution procedure of vanadium pentoxide, which is widely used as a catalyst for production of sulfuric acid or an oxide reaction of the numerous organic compounds, was investigated. Reagent of vanadium pentoxide was completely dissolved in aqua regia-$H_2O_2$-HF solution, but plate type of vanadium pentoxide sample was not clearly dissolved with mixed acids. Thus, in order to establish the dissolution procedure for plate type of vanadium pentoxide, the solubility of vanadium pentoxide was investigated through comparison of acid treatment-fusion and microwave digestion methods. The optimized acid for dissolution of vanadium compound was found to be mixing acids of aqua regia, $H_2O_2$ and HF. Acid-fusion and microwave digestion methods have a similar property in the solubility of vanadium compound, but the latter was more quick and convenient procedure. The content of vanadium pentoxide was found to be $97.9{\pm}0.9%$ using an inductively coupled plasma atomic emission spectrometer after dissolution of a sample with the microwave digestion system.