• Polymer(Korea)
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• v.37 no.4
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• pp.518-525
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• 2013

To improve the mechanical properties of polypropylene (PP) biocomposites reinforced with sulfuric acidtreated green algae (SGA), SGA/graphite nanoplatelets (GNP)/PP biocomposites were prepared and their properties were evaluated depending on the particle size and content of GNP. The flexural and impact strength of SGA/GNP/PP biocomposites decreased with the addition of GNP, whereas the flexrual and storage moduli were greatly improved with increasing GNP loading. SGA/GNP/PP biocomposites reinforced with GNP5 showed generally better mechanical properties compared to that reinforced with GNP15 mainly due to the improved dispersion of the smaller GNP. SGA/GNP/PP biocomposites reinforced with GNP5 showed a lower resistance to the thermal expansion because the relatively uniform dispersion of smaller GNP was responsible for the effective heat transfer to the polymer matrix. As a result, SGA/GNP/PP biocomposite was acceptable for the general purpose application due to the improved flexural resistance, storage moduli, and damping characteristics.

• The Korean Journal of Ecology
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• v.16 no.4
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• pp.409-416
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• 1993

After spraying simulated sulphuric acid rain (SSAR) to the leaves of Glycine max, Quercus aliena var. pellucida and Pinus rigida, the leachates were consecutively collected and quantitatively determined for the concentration of K and Ca. The amount of the leached ion decreased with subsequent acid treatment for all plants. But as the pH of SSAR decreased, the amount of the leached ion increased. The cumulative quantities of K leached from each species were 1.04 to 1.46 times higher at pH 4.0, 1.09 to 1.58 times higher at pH 3.5 and 1.24 to 2.03 times higher at pH 3.0 compared with pH 5. 6 treatments. The cumulative quantities of Ca leached from each species were 1.23 to 1.47 times higher at pH 4.0, 1.50 to 1.92 times higher at pH 3.5, and 2.45 to 3.30 times higher at pH 3.0 compared with pH 5.6 treatments. The Ca /K ratio in 1000 ml leachate was 1.10 to 2.91 for Q. aliena var. pellucida and 1.68 to 2.98 for P. rigida, but 0.66 to 0.91 for G, max. The Ca /K ratio in 1000 rnl leachate increased for all three species, as the pH of SSAR decreased. Foliage analysis after acid rain treatment showed leaching effect at pH 3.0.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.347-356
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• 1992

Various kaolin samples with different alumina content were prepared from calcined admixture of kaolin and ammonium sulfate by varying the treatment time in sulfuric acid. Samples were nitridated under N2 or N2-H2 atmosphere with changing the amount of added carbon, the reaction time and temperature. As the alumina content lowered, the size of kaolin particles decreased and the specific surface area increased. XRD analysis indicated that ${\alpha}$-quartz remained by decomposition of halloysite and meta-halloysite. Experimental results of nitridation behavior are summerized as follows; 1) Nitridation under N2 atmosphere. With the increase of C/SiO2 ratio and with the decrease of Al2O3 content, disappearance of XRD pattern peaks of mullite, ${\alpha}$-quartz and ${\alpha}$-Al2O3 were accelerated at 1300$^{\circ}C$. SiC was the main phase in the reaction product of acid-treated kaolin samples nitridated at 1300$^{\circ}C$ for 10 hours regardless of C/SiO2 ratio. But the XRD peak intensities of ${\beta}$-Si3N4, ${\beta}$-sialon and SiC did not show much difference when untreated raw kaolin was fired at the same condition. When the ratio of C/SiO2 was 3.5, ${\beta}$-sialon and ${\beta}$-Si3N4 existed in the reaction product of about 22% alumina containing kaolin sample fired at 1350$^{\circ}C$ for 7 hours. Only ${\beta}$-sialon existed in the same sample fired at 1400$^{\circ}C$ for 10 hours. ${\beta}$-sialon was obtained from all of the acid-treated kaolin samples fired at 1400$^{\circ}C$ for 40 hours, but AlN and SiC remained in the untreated kaolin sample. Z value of the ${\beta}$-sialon obtained from the 22% alumina containing kaolin sample fired at 1400$^{\circ}C$ for 40 hours was about 1.3(XRD) and 1.5(EDS). 2) Nitridation under 80N2+2OH2 mixed gas atmosphere with the C/SiO2 ratio of 1 Mullite was not found, but ${\alpha}$-Si3N4, and ${\beta}$-sialon were present in the reaction product of about 22% alumina containing kaolin sample fired at 1300$^{\circ}C$ for 10 hours. When untreated kaolin sample was nitridated at the same condition, mullite remained. AlN and SiC were not found in the reaction product of about 22% alumina containing kaolin sample fired at 1350$^{\circ}C$ for 5 hours. On the other hand, AlN and SiC remained in the product of untreated kaolin fired at the same condition.

• Applied Biological Chemistry
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• v.42 no.1
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• pp.73-78
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• 1999

Acid mine drainage (AMD) results from sulfuric acid produced by the oxidation of pyrite, and contains large amounts of toxic elements. In the neutralization of AMD, iron and aluminum hydroxides are the major precipitates and those two can be separated with two-phase neutralization. In this study, removal of toxic elements by the two phases of neutralization was investigated using an AMD collected from the abandoned antimony mine in Gachang, Taegu. Contents of As, Cd, Cu, Mn, Pb and Zn in the AMD were higher than the criteria of river water quality or permissible waste water discharge. In the first phase, the AMD was neutralized to several % (25, 50, 75, 100, and 125) of $Fe(OH)_3$ equivalence point with solid $Ca(OH)_2$. In the second phase, the supernatant of the first phase neutralization was titrated to pH 7.5. After neutralization of the AMD to 100% of the $Fe(OH)_3$, equivalence point, most of Fe and Pb were removed but levels of As, Cd, Cu, Ni, Mn, and Zn were not reduced in the supernatant solution. In the second phase neutralization, levels of those toxic elements in the supernatants dropped below the wastewater discharge or river water quality criteria. This result suggests that the precipitate formed in the first phase of the neutralization process may be disposed without any special cares. Thus the two-phase neutralization scheme can reduce the cost of disposing precipitates containing toxic metals in comparison with the monophase neutralization scheme.

• Korean Chemical Engineering Research
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• v.49 no.3
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• pp.330-337
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• 2011

In this research, the preparation processes for making a series of $\omega$-mercapto alkylamine 1 and $\omega$-mercapto alkanoic acid 2 useful for studying of the self-assembled monolayer(SAM) are described. The preparation methods of the first goal materials, $\omega$-mercapto alkylamines 1 were carried out as follows: First, $\omega$-phthalimide alkanol 3 was synthesized from commercially available potassium phthalimide derivatives and $\omega$-bromoalkanol in DMF at $80{^{\circ}C}$ via substitution reaction. After refluxing $\omega$-phthalimide alkanol 3 with hydrazine hydrate in ethanol followed by treating with c-HCl, $\omega$-aminoalkanol 4 was obtained in 76-98% yield, accompanied with side-product 5. Bromination of hydroxyl moiety of $\omega$-aminoalkanol 4 using aqueous hydrobromic acid furnished $\omega$-bromoamine 6 in 34-97% yields. Substitution reaction 6 with thiourea in 95% ethanol gave $\omega$-aminoalkanthiuronium 7, which was treated with aqueous strong base and aqueous strong sulfuric acid gave desired products, $\omega$-mercapto alkylamines 1 through overall 5 steps. The second target material, $\omega$-mercapto alkanoic acid 2 was prepared via 2 steps. $\omega$-bromo alkanoic acid was reacted with thiourea to give $\omega$-thiourea alkanoic acid 7 in 69-85%, which was treated with aqueous strong base and strong acid to furnish $\omega$-mercapto alkanoic acid 2 in 50-98%. The fabricated long-chain alkylthiol(LCAT) can be used as linkers to immobilize protein, enzyme and various kinds of biomolecules on the surface of metallic materials(Au, Pt, Ti) by SAM, and can be useful chemical tools for the application study on the surface modification of metallic materials.

• Journal of Korean Society of Forest Science
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• v.77 no.3
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• pp.259-268
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• 1988

For the purpose of examining the effects of simulated acid rain on nutrient contents of plant tissues in Pintos densiflora seedlings and Forsythia koreana rooted cuttings, the experimental design of randomized block arrangement with three replications was implemented in the experimental field of Yesan National Agricultural Junior College. One-year-old Pinus densiflora seedlings and Forsythia koreana cuttings were planted in the pots filled the mixed soils(nursery soil : forest soil of siliceous sandy loam=1 : 1 v/v) in the early spring of 1986. The regime of artificial acid rain, in terms of spray frequency per month and spray amount at single treatment per plot, was simulated on the basis of climatological data averaged from 30 years records. Simulated acid rain(pH 2.0, pH 4.0, and pH 5.5 as control) containing sulfuric and nutric acid in the ratio of 3 : 2(chemical equivalant basis) diluted with ground water were treated on the experimental plants under condition of cutting off the natural precipitation with vinyl tunnel, during the growing season(May 1 to August 31) in 1986. The results obtained in this study were as follow : (1) As for the nitrogen contents in plant tissues, P. densiflora increased significantly in one-year-old stembranch and root tissues, and F. koreana increased significantly in leaf and root tissues, as the pH levels of acid rain decreased. (2) The available phosphate contents in root tissues of P. densiflora, and in leaf and root tissues of F. koreana were significantly decreased, as the pH levels of acid rain decreased. (3) $K_2O$, CaO and MgO contents in plant tissues were significantly decreased in the both species as the pH levels decreased. And the effects of acid rain on F. koreana were higher than those of P. densiflora. (4) Sulfur contents of plant tissues in the both species were increased at pH 2.0 treatment. There were significant differences among three acid rain treatments in leaf and root tissues of P. densiflora, and in all parts of F. koreana. (5) In the effects of simulated acid rain on the both species and the tested soils, in general, F. koreana revealed higher sensitiveness than P. densiflora, and the lower pH levels of simulated acid rain were treated, the more sharp reaction was showed.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.43-52
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• 1988

One-year-old seedlings of Ginkgo biloba were treated with various simulated acid rains(pH 2.0, pH 3.0, pH 9.0 and pH 5.0) to examine the effects of simulated acid rain on the chemical properties of the tested soil. The seedlings were grown in a pot($4500cm^3$)containing one of three different soils(nursery soil, mixed soil and sandy soil). Simulated acid rain was made by diluting sulfuric and nitric acid solution($H^1SO^4$ : $HNO^3$ =3 : 1, V/V) with tap water and tap water(pH 6.4), and treated by 5mm each time for three minutes during the growing seasons(April to October 1985). Acid rain treatments were done three times per week to potted seedlings by spraying the solutions. The chemical properties of potting media were compared among three soil types as well as among the various pH levels. The results obtained in this study were as follows : 1. Exchangeable calcium and magnesium contents and base saturation of the soil decreased with decreasing pH levels of acid rain, and their decreasing rates were as follows : sandy soil was the highest, followed by mixed and nursery soils, However, exchangeable aluminum content rather increased as the pH levels decreased. 2. Available phosphate in the soil decreased as the pH levels of acid rain decreased. Its content increased in nursery soil, compared with those before acid gain treatment, Gut decreased in mined and sandy soils. 3. Soil sulfate and nitrate contents increased remarkably as the pH levels decreased, and the only significant difference in the sulfate was found among the pH levels. Soil sulfate content was the highest in nursery soil, followed by mixed and sandy soils.

• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.453-459
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• 1988

The purposes of this study were to evaluate the effects of acid rain on tree growth and on the mycorrhizal formation and the effects of mycorrhizae on the host tolerance to acid rain. Simulated acid rain was applied for five months to Pinus $rigida{\times}taeda$ seedlings in pots inoculated with Pisolithus tinctorius (Pt) and Suillus luteus (Sl). Mycelial inocula of Pt and Sl were either mixed with entire pot soil (Mix) or casted as a band (Band) after soil sterilization. Three pH levels of acid rain (pH 3.0, 4.5 and 6.4 adjusted by 3 : 1 mixture of sulfuric and nitric acids) were tested. Pt-Mix was most effective in growth stimulation and resulted in 45-90% increase in tree height in sandy loam. Pt-Band was less effective than Pt-Mix in growth stimulation and mycorrhizal formation. Simulated acid rain at pH 4.5 stimulated height growth by 10-55%, while acid rain at pH 3.0 did not significantly affect the height growth. The top/root ratio was increased by pH 4.5 treatment, while pH 3.0 treatment reduced it. Mycorrhizal infection rate was not affected by acid rain. Pt inoculation reduced acid-induced leaf injury by 28-58% in both pH 3.0 and 4.5 compared with un-inoculated plants. Sl was also effective in growth enhancement, but was less effective than Pt in both mycorrhizal infection and reducing leaf injury.

• Journal of Korean Society of Forest Science
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• v.81 no.1
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• pp.30-39
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• 1992

Artificial acid rain(pH2.0, 3.0, 4.0 and 5.0) was treated on the seeded pots of 4 species to examine its effects on germination, leaf injury and seedling growth. Aluminum ammonium sulfate solution (0.5, 1.0 and 2.5mM) and artificial acid rain (pH3.0, 4.0 and 5.0) were treated on the seeded germinators of 3 species to examine its effects on germination and radicle growth. Artificial acid rain was prepared by diluting sulfuric acid with ground water and ground water(pH6.5) was used as control. Artificial acid rain was sprayed to seeded pots three times per week. About 5mm of artificial acid rain was treated each time from early April to early October, 1991. Germination, seedling establishment, radicle growth, leaf injury and seedling growth were measured and compared among the treatments. The results were summarized as follows 1. Germination, seedling establishment rate of Pinus densiflora were highest on the pH5.0 pot whereas those of Ailanthus altissima was highest on the control pot, and those of Magnolia sieboldii showed the highest value on the pH3.0 pot. 2. The differences in seedling height of Pinus densiflora and Pinus rigida were significant among the treatment levels of acid rain, whereas those of Magnolia sieboldii and Ailanthus altissima were not significant. Seedling heights of Pinus densiflora and Pinus rigida were highest on the pH3.0 pot, and that of Magnolia sieboldii was highest on the pH4.0 pot, and that of Ailanthus altissima was highest on the control pot. 3. Seedling dry weights of Pinus densiflora. Pinus rigida, and Ailanthus altissima differed significantly among the treatments, but that of Magnolia sieboldii did not differ. Highest seedling dry weights of Magnolia sieboldii and Ailanthus altissima were observed on the pH4.0 pot, and that of Pinus densiflora was observed on the pH3.0 pot, and that of Pinus rigida was observed on the pH5.0 pot. 4. With decrease of pH value of artificial acid rain, the number of injured needle and injured individual tended to be increased. 5. The differences in effects of soil acidity were highly significant among the treatments for all species. 6. Radicle growth of Pinus densiflora differed significantly among pH levels and aluminum concentrations.

• Journal of the Korean Wood Science and Technology
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• v.37 no.3
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• pp.255-264
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• 2009

To evaluate the effects of chemical pretreatments of lignocellulosic biomass on enzymatic hydrolysis process, Populus euramericana was pretreated for 1 hr with 1% sulfuric acid ($H_2SO_4$) at $150^{\circ}C$ and 1% sodium hydroxide (NaOH) at $160^{\circ}C$, respectively. Before the enzymatic hydrolysis, each pretreated sample was subjected to drying process and thus finally divided into four subgroups; dried or non-dried acid pretreated samples and dried or non-dried alkali pretreated samples and chemical and physical properties of them were analyzed. Biomass degradation by acid pretreatment was determined to 6% higher compared to alkali pretreatment. By the action of acid ca. 24.5% of biomass was dissolved into solution, while alkali degraded ca. 18.6% of biomass. However, reverse results were observed in delignification rates, in which alkali pretreatment released 2% more lignin fragment from biomass to the solution than acid pretreatment. Unexpectedly, samples after both pretreatments were determined to somewhat higher crystallinity than untreated samples. This result may be explained by selective disrupture of amorphous region in cellulose during pretreatments, thus the cellulose crystallinity seems to be accumulated in the pretreated samples. SEM images revealed that pretreated samples showed relative rough and partly cracked surfaces due to the decomposition of components, but the image of acid pretreated samples which were dried was similar to that of the control. In pore size distribution, dried acid pretreated samples were similar to the control, while that in alkali pretreated samples was gradually increased as pore diameter increased. The pore volume which increased by acid pretreatment rapidly decreased by drying process. Alkali pretreatment was much more effective on enzymatic digestibility than acid pretreatment. The sample after alkali pretreatment was enzymatically hydrolyzed up to 45.8%, while only 26.9% of acid pretreated sample was digested at the same condition. The high digestibility of the sample was also influenced to the yields of monomeric sugars during enzymatic hydrolysis. In addition, drying process of pretreated samples affected detrimentally not only to digestibility but also to the yields of monomeric sugars.