• Korean Journal of Environmental Agriculture
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• v.19 no.3
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• pp.223-227
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• 2000

Absorption of Cadmium(Cd) and Arsenic(As) by lettuce following to the change of polyamine content in lettuce were examined to find the effect of these elements on lettuce growth and on the basic resistance mechanism. As the contents of Cd and As were increased in soil, the contents of these elements were significantly increased in lettuce but lettuce growth was decreased. Sequential fractionation experiment of the Cd and As treated soil was shown that exchangeable, dilute acid extractable, and organically bound form, which were more mobile and phyto-available, of Cd were increased by 5.6, 42.9, and 56.7% during a growing season whereas 17.6, 25.0, and 24.1% were increased in case of As, respectively. Specially, the Cd content of leaves and roots in lettuce was positively correlated with exchangeable, dilute acid extractable, and residual form of Cd in the treated soil. However, the As content of roots in lettuce was positively correlated with all chemical forms of As in the treated soil. The contents of putrescine and cadaverine, a kind of polyamine, were also increased in lettuce as both elements were increased in soil.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.108-117
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• 2017

Laver, Porphyra, is distinctive for its high content of proteins and polysaccharides such as porphyran and hemicellulose. The chemical properties of the polysaccharides extracted with different extraction methods such as hot water, dilute acid(pH 4.0) or alkali solution(2N NaOH) were examined to investigate the suitable extraction conditions for porphyran and hemicellulose from laver. For porphyran extraction, dilute acid solution was more preferable to hot water and alkali solution because of its higher 3,6-anhydrogalactose content and lower protein content. However, alkali solution was more suitable to extract the hemicellulose because of higher mannose content indicating the extraction of mannan. To decrease contamination of the polysaccharides with protein, the dried lavers were pretreated with enzymes (Protamex, Flavourzyme, Alcalase, Viscozyme) before hot water extraction. All enzyme pretreatments increased the yield of polysaccharides by compared with control (enzyme unpretreated) and Flavourzyme pretreatment was most effective to decrease protein contamination in the polysaccharide. All viscosities of porphyran solutions pretreated by enzymes were lower compared to the control porphyran solution and showed pseudoplastic behavior with yield stress. In case of alkali extraction of residues obtained after enzyme hydrolysis and hot water extraction, protease pretreatment increased the mannose contents in the polysaccharide while the xylose content was increased by Viscozyme pretreatment.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.326-332
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• 2012

Among the samples prepared by various pre-treatment methods, the one pretreated by dilute sulfuric acid showed the highest glucose yield in the enzymatic hydrolysis. Statistical analysis of enzymatic hydrolysis revealed that the glucose yield was in proportion to the enzyme dosage, the ratio of the pre-treated sample to the buffer solution, and the reaction time and that the effect of enzyme dosage was predominant in the experiment range. In addition, the glucose yield was estimated to be 76.1% at an optimal enzymatic hydrolysis condition. In a separate hydrolysis and fermentation (SHF), Saccharomyces cerevisiae converted over 80% of glucose from the enzymatic hydrolysis of pre-treated wasted corn stalk by dilute sulfuric acid to bioethanol with 37% of ethanol yield and 0.42 $g/L{\cdot}hr$ of productivity. In the simultaneous saccharification and fermentation (SSF), 59.5% of conversion from glucan to ethanol and 0.20 $g/L{\cdot}hr$ of productivity were achieved. In both SHF and SSF, approximately 88 g of bioethanol could be obtained from 1 kg of wasted corn stalk. The possible amount of bioethanol in Gangwon province were estimated to be 1.9 kiloton with the assumption of the 50% of collection ratio.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2342-2348
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• 2014

Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic$^{(R)}$ F68 ($(EO)_{75}(PO)_{30}(EO)_{75}$) triblock copolymer to produce poly{(lactic acid)$_m$-co-(glycolic acid)$_n$}-b-poly(ethylene oxide)$_{75}$-b-poly(propylene oxide)$_{30}$-b-poly(ethylene oxide)$_{75}$-b-poly{(lactic acid)$_m$-co-(glycolic acid)$_n$} (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate ($Sn(Oct)_2$) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by $^1H$- and $^{13}C$-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with $^1H$-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:$H_2O$ = 10:90 by volume at $25^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.309-314
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• 1984

The species and equilibria of uranium and vanadium have been investigated in the various concentration of perchloric, hydrochloric and sulfuric acid by anion exchange chromatography. In the concentration range of $0.01\;{\sim}\;0.5M$ hydrochloric and $0.01\;{\sim}\;0.5M$ perchloric acid, uranium seems to be $UO_2^{2+}$species and in higher concentration than 0.5M hydrochloric acid $UO_2^{2+}$seems to form the chloride complex ion as $UO_2Cl^+$, $UO_2Cl_2$, $UO_2Cl_3^-$ and $UO_2Cl_4^{2-}$ according to the increase of the hydrochloric acid concentration. In the dilute(0.01N) sulfuric acid the adsorbability of uranium on anion exchange resin is strong and then decreases with increasing the sulfuric acid concentration. From this result we conclude that $UO_26{2+}$ formed the complex ion as $UO_2(SO_4)_2^{2-}$. In the perchloric acid of $0.01\;{\sim}\;0.5N$ concentration the existing equilibrium of vanadium and its constant calculated at $20^{\circ}C$ is $1.9{\times}108$ for $H_2V_{10}O_{28}^{4-}$ + $14H^+$ = $10VO_2^+ + 8H_2O$. The elution behaviors of vanadium in the hydrochloric and sulfuric acid are smiliar to those in perchloric acid.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1092-1095
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• 1999

The well-known mixed-acid process for the aromatic nitration requires subsequent separation of spent acid, mainly dilute sulfuric acid. A novel nitration process using $HNO_3-NO_2-O_3$ was tested in a small pilot scale with 3 mol of p-nitrotoluene. Nitrogen dioxide(14.3 mol) was added three times in parts into the solution of p-nitrotoluene and $HNO_3$(6 mol) in dichloroethane. The nitration proceeded to more than 97% conversion within 5.5 h using 0.871 mol/h of ozone. As a clean process of aromatic nitration, this method is expected to replace the present process which causes the environmental problems.

• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.262-268
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• 1973

p-Phenylenediamine was tetrazotized with sodium nitrite in an excess amount of concentrated hydrochloric acid media at -10$^{\circ}$C. It was also tetrazotized almost completely in 45% perchloric acid media. The two diazo groups in the tetrazonium salt were substituted by halogen, and the degree of tetrazotization reaction was observed by dihalobenzene yielded. The result of the tetrazotization was dependent upon the stability of the tetrazonium salt, and the stability was determined by concentration and quantity of the acid media. In dilute acid media the tetrazonium salt was unstable and completely decomposed. In concentrated acid media, though the tetrazonium salt was stable, tetrazotization reaction was retarded. To harmonize the two opposing tendencies it was advisable to find the optimum acidity of media at which the salt was fairly stable. About $40{\sim}45$% of the acid media was suitable. The fact that the $H^+$ ion behaved as a negative catalyst supported the assumption that the diazotization reaction is primarily a reaction between the free amine and a nitroso group. The reaction of tetrazotization is expressed with respect to the kinetics and mechanism of diazotization.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.407-412
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• 2008

As an activation procedure, in this study, the oxidation treatment of needle cokes with a dilute nitric acid and sodium chlorate $(NaClO_3)$, combined with heat treatment, was attempted. The structures of acid-treated and pyrolyzed coke were examined with XRD, FESEM, elemental analyzer, BET, and Raman spectroscopy. The behavior of double layer capacitance was investigated with the analysis of charge and discharge. The structure of needle coke treated with acid was revealed to a single phase of (001) diffraction peak after 24 h. On the other hand, thecoke oxidized by heat treatment was reduced to a graphite structure of (002) at $300^{\circ}C$. The distorted graphene layer structure, derived from the process of oxidation and reduction of the inter-layer, makes the pores by the electric field activation at the first charge, and generates the double layer capacitance from the second charge. The cell using pyrolyzed coke with 24 h acid treatment and $300^{\circ}C$ heat treatment exhibited the maximum capacitance per weight and volume of 33 F/g and 30 F/mL at the two-electrode system in the potential range of 0~2.5 V.

• Journal of Korean Society of Forest Science
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• v.41 no.1
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• pp.1-6
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• 1979

1. The study was conducted on the optimum condition of the treated substrate with dilute sulphuric acid solution and cellulase for saccharification. The wood (saw dust) of Alnus hirsuta Rupr. (10~15 years) was treated with 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, $H_2SO_4$ solution at $1.5kg/cm^2$ for 15min., 30min., 45min., and 60min., followed by thermal treatment at $190^{\circ}C$ for 30min., and screening with 60 mesh sieve, after which to 0.5 grams of each sample was added 0.5ml cellulase solution, and 50ml 0.1M acetic acid buffer solution (pH 5.0), after incubating at $40^{\circ}C$ for 96hr. 2. The crude cellulase of Trichoderma viride Perx. ex. Fr. SANK 16374 was produced by the submerged culture process and produced in the culture fluid was salted out quantitatively by the use of ammonium sulfite. 3. Reducing sugar was determined by the 3.5-dinitrosalicylic acid (DNS) method. 4. The reducing sugar was increased with increase of the sulphuric acid concentration and saw dust was treated with 1.5% $H_2SO_4$ solution at $1.5kg/cm^2$ for 45min. showed the best saccharification (16.0%). The reducing sugar formation did not show statistically significant in 5% levels by thermal treatment time 45min. and 60min. 5. The substrate for cellulase which was treated with 0.9% $H_2SO_4$ solution at $1.5kg/cm^2$ for 60min. showed the best reducing sugar formation (23.6%). And did not show significant difference in 5% levels at 0.9%, 1.2%, and 1.5% $H_2SO_4$ solution.

• Clean Technology
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• v.17 no.2
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• pp.156-165
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• 2011

The process for bioethanol production from lignocellulosic biomass was studied through process simulation using PRO/II. Process integration was conducted with concentrated acid pretreatment, hydrolysis process, SMB (simulated moving bed chromatography) process and pervaporation process. Energy consumption could be minimized by the heat recovery process. In addition, material and energy balance were calculated based on the results from the simulation and literature data. A net production yield of 4.07 kg-biomass and energy consumption value of 3,572 kcal per 1 kg ethanol were calculated, which is indicating that 26% yield increase and 30% energy saving compared to the bioethanol production process with dilute-acid hydrolysis (SRI report). In order to make it possible, sugar conversion yield of cellulose and hemi-cellulose is to be reached up to 90% and fermentation of xylose needs to be developed. In order to reduce the energy consumption up to 30%, the concentration of acid solution after being separated by 5MB should exceed 20%. If acid/sugar separation by SMB process is to be practical, the bioethanol process designed in this study can be commercially feasible.