• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.472-477
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• 2001

Spent catalysts containing platinum were generated in petroleum refinery and other chemical industries. The reclamation of precious metals from such wastes has long been attempted in view of their rare, expensive and indispensable nature. In this study, the recovery of platinum from petroleum catalysts was attempted by a method consisting mainly of dissolving alumina substrate with sulfuric acid thereby concentrating insoluble platinum. Also, platinum dissolved partially in sulfuric acid was recovered by a cementation method using aluminum metal as a reductive agent. The effect of temperature, time, concentration of sulfuric acid. and pulp density on the dissolution of substrate was investigated. When the substrate of platinum catalyst was ${\gamma}$-AI$_2$O$_3$ about 95% alumina was dissolved in 6.0M sulfuric acid at 10$0^{\circ}C$ for 2 hours. When the substrate was the mixture of ${\gamma}$-A1$_2$O$_3$and $\alpha$-A1$_2$O$_3$about 92% was dissolved after 4 hours. As a result, more than 99% of platinum could be recovered by this method and aluminum sulfate was obtained as byproduct.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.432-436
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• 2001

In this study, calcium sulfate(gypsum) powder was obtained using waste sulfuric acid and stainless refinery sludge by- produced from chemical reagent and the iron industry, by the neutralization of waste sulfuric acid. As variables for the experiment the mole ratio of the H$_2$SO$_4$ : Ca(OH)$_2$, the pH, the reaction temperature and time, the amount of catalyst were used. The crystal shape and microstructure of obtained powder were observed by XRD and SEM, and the thermal property was investigated by DTA. As the NaCl is added 0~20wt% as a catalyst to the H$_2$SO$_4$ : Ca(OH)$_2$, system it can be found that the crystal shape goes through the processes as follows : gypsum dihydratlongrightarrowgypsum hemihydrate＋gypsum dihydratelongrightarrowgypsum hemihydrate. And gypsum hemihydrate is $\beta$-type as the result of DTA. As waste sulfuric acid and stainless refinery sludge were used, the pH of reacted solution (which was 0.8) was rapidly raised up to 8~9 by the addition of stainless sludge and gypsum dihydrate was produced as a by-product. Therefore, it was found that stainless refinery sludge is sufficiently applicable for the neutralization of waste sulfuric acid.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.139-140
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• 2023

In this study, red mud with low recyclability was manufactured as liquid red mud, neutralized with sulfuric acid and nitric acid, and then added to cement paste to conduct research on physical and chemical properties. As a result, liquid red mud-added cement paste neutralized with sulfuric acid and nitric acid showed higher compressive strength after one day than cement paste with plain and non-neutralized liquid red mud. This indicates that nitric acid and sulfuric acid neutralization can increase initial strength.

• New & Renewable Energy
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• v.19 no.4
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• pp.11-19
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• 2023

Levulinic acid (LA) derived from cellulosic biomass, serves a crucial intermediate that can be used in various chemical conversions. This study focused on optimizing the production of LA using two types of pretreated rice husk (de-ashed and delignificated cellulosic biomass) in a batch reaction system through catalytic conversion with sulfuric acid. To determine the optimal conditions, the conversions of glucose and α-cellulose were examined to compare the effects of pretreatment on the rice husk. The experimental parameters covered a broad spectrum, including temperatures ranging from 140℃ to 200℃, a reaction time was up to 600 minutes, and a substrate to catalyst (acid solution) ratio of 100 g/L. The highest LA yield was 44.8%, achieved from de-ashed rice husk with 3.0 wt.% of sulfuric acid at 180℃ and with a reaction time of 180 minutes. In the case of the delignificated rice husk, a LA yield of 43.6% was obtained with 3.0 wt.% of sulfuric acid at 200℃ and with reaction time of 30 minutes.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.76-85
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• 2015

In this study, we investigated optimal reaction conditions for furfural production from lignocellulosic biomass by two-stage acid treatment. Furfural produced by this method was recovered using XAD-4 resin. Oxalic and sulfuric acid were used as catalysts for the first stage of treatment. The concentration of xylose in the hydrolysate obtained from the first stage was $18.86g/{\ell}$ with oxalic acid and $19.35g/{\ell}$ with sulfuric acid. The concentration of oligosaccharide was relatively high when sulfuric acid was used. Maximum yield of furfural, that is, 55.10% ($6.71g/{\ell}$), was obtained when oxalic acid was used for the first stage and $0.1m{\ell}$ of sulfuric acid was used for the second stage of treatment for 90 min. Furfural production yield increased with increasing the reaction time. Most of the furfural produced by this two-stage treatment method was recovered using XAD-4 resin.

• The Korean Journal of Ecology
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• v.21 no.1
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• pp.65-72
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• 1998

Various effects of simulated acid rain by $HNO_3$ and $H_2SO_4$ with pH 3.2, 4.2 and 5.6 were investigated in Melilotus suaveolens Ledeb, a biennial legume dominating the disturbed and poor soil vegetations. The nitric acid treatment of pH 3.2 resulted in 121% increase of the plant height compared to that of pH 5.6 during early growth, although 17% decrease was detected with the sulfuric acids. During 14 days of treatment, leaf biomass and chlorophyll content increased 168% and 133% with pH 3.2 nitric acid rain but decreased 20% and 38%, respectively, with sulfuric acid rain. Nitrogen content in various organs was also determined after 42 days of nitric acid treatment. It increased 480% and 387% by pH 3.2 and 4.2 in leaves, 212% and 214% in stems and 247% and 249% in roots. However, the same treatment with the sulfuric acid showed a considerable reduction in this content, indicating that the nitric acid was a nitrogen source. Nodule formation assayed revealed 15% decrease with pH 3.2 in contrast to 157% increase in pH 4.2, further suggesting an enhancement effect by the additional nitrogen source. Contrary to this, the nodule formation was reduced up to 43-71% by sulfuric acid rains. Specific nitrogen fixation activities of nodules estimated at pH 3.2, 4.2 and 5.6 nitric acid rain were 36.7, 42.8 and 47.3 ${\mu}mol\;C_2H_4{\cdot}g^{-1}\;fw\;nodule{\cdot}h^{-1}$, while those of sulfuric acid rain exhibited 1 nmol $C_2H_4{\cdot}plant^{-1}{\cdot}h^{-1}$ with pH 3.2, 177 with pH 4.2 and 179 with pH 5.6, yet it increased 2, 115 and 286 respectively corresponding to the three sulfuric acid concentrations. Further implications of the simulated acied rain were also discussed in the study.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.561-569
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• 2023

Furfural is a platform chemical that is produced from xylose, one of the hemicellulose components of lignocellulosic biomass. Furfural can be used as an important feedstock for phenolic compounds or biofuels. In this study, we compared and optimized the conditions for producing furfural from xylose in a batch system using two types of catalysts: sulfuric acid, which is commonly used in the furfural production process, and formic acid, which is an environmentally friendly catalyst. We investigated the effects of xylose initial concentration (10 g/L~100 g/L), reaction temperature (140~200 ℃), sulfuric acid catalyst (1~3 wt%), formic acid catalyst (5~10 wt%), and reaction time on the furfural yield. The optimal conditions according to the type of catalyst were as follows. For sulfuric acid catalyst, 3 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 10min of reaction time resulted in a maximum furfural yield of 59.0%. For formic acid catalyst, 5 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 150 min of reaction time resulted in a furfural yield of 65.3%.

• Journal of the Korean Applied Science and Technology
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• v.3 no.2
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• pp.29-34
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• 1986

The sulfuric acid sulfonation of 2-aminonaphthalene was preformed at $30^{\circ}C{\sim}200^{\circ}C$ for $1{\sim}15$ hours, using $4{\sim}10$ parts of 90% sulfuric acid${\sim}$20% oleum. This reaction was influenced by many factory such as reaction temperature, reaction time, strength of sulfuric acid and amount of sulfuric acid and among these factors, the effect of the reaction temperature was considerable. The main products of this reaction were Dahl's acid (2-aminonaphthalene-5-sulfonic acid, Broenner's-acid (2-aminonaphthalene-6-sulfonic acid), amnio-F-acid(2-aminonapthalene-7-sulfonic acid), and Baden acid (2-aminonaphthalene-7-sulfonic acid) and another isomers such as Tobia's acid (2-aminonaphthalene-1-sulfonic acid) and 2-aminonaphthalene-4-sulfonic acid were not formed. Of these isomeric acids, those containing the sulfonic acid group in an ${\alpha}-position$, namely, Dahl's acid and Baden acid, are simultaneously formed by sulfonation at low-temperature ($30{\sim}100^{\circ}C$), whilst those containing the sulfonic acid group in a ${\beta}$-position, namely, Broenner's acid and amino-F-acid, are formed simultaneously by sulfonation at high temperatures($150^{\circ}{\sim}200^{\circ}$).

• KSBB Journal
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• v.13 no.3
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• pp.312-319
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• 1998

The dilute-acid pretreatment/hydrolysis of hemicellulose in oak wood using a percolation reactor was investigated. The experimental conditions ranged 160∼180$^{\circ}C$ and 0.05∼0.2 wt.% sulfuric acid. XMG(xylan+mannan+galactan) recovery was higher when sulfuric acid was used as leaching solvent than water. Also it was important for high XMG recovery to keep leaching temperature higher after reaction. XMG recovery was decreased as the size of wood chips was increased. At an optimum condition (reaction condition= 170$^{\circ}C$, 0.1% sulfuric acid, 1ml/min, 10min, leaching condition=0.1% sulfuric acid, 2mL/min, 20 min), the product yield and the sugar concentration were about 92% and 2.7%, respectively.

• Carbon letters
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• v.2 no.2
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• pp.109-112
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• 2001

For the adsorption of ammonia, activated carbon fibers (ACFs) were subjected to sulfuric acid treatment in order to modify the surface functional groups. The surface acid and base value of ACFs were measured using titration and FT-IR spectrometry. SEM was used to investigate the surface morphology. Acid treatments by $H_3PO_4$, $H_2SO_4$, and $HNO_3$ were performed to increase the adsorption capacity of $NH_3$. As a result, Cellulose-based ACF has high adsorption capacity for ammonia. The ammonia removal efficiency of ACF was the maximum which was treated by 15 wt% sulfuric acid at $100^{\circ}C$ for 60 min. The average pore diameter little increased from $19{\AA}$ to $20.8{\AA}$ and the specific surface area of ACF considerably decreased and acid values increased by 15 wt% sulfuric acid treatment. Ammonia reacted with sulfonyl radicals. After adsorption of ammonia, white material was grown on the surface of ACF through the adsorption of ammonia and it was determined to ammonium sulfate.