• Journal of the Korean Applied Science and Technology
• /
• v.27 no.4
• /
• pp.475-481
• /
• 2010

Elution effect was studied by the reactions between Electric arc furnace(EAF)dust and conc. or dil. sulfuric acid for the purpose of recoverying of the useful metals afterwards. The methods of mixing with acids and EAF dust for the elutions were depend on the ratios of acid/EAF dust. Experimental results showed that increased the ratios of sulfuric acids, decreased the elution effects are on the Zn, Fe and Mn, and conc. sulfuric acid showed higher elution effects than dil. sulfuric acids for the all metals. But in case of Pb, dil. sulfuric acid showed higher elution effects than conc. sulfuric acids conversely. Furthermore, the reason of the extreamly low quantities of eluted Pb is caused by the low solubilities by sulfuric acids compared to the other metals, as the results of the insoluble Pb is removed by the process of filtering.

• Journal of Environmental Science International
• /
• v.12 no.6
• /
• pp.659-664
• /
• 2003

The experiment was carried out to investigate the effects of sulfuric acid and nitric acid among the main components of simulated acid rain (SAR) on the growth of vegetative organs and seed germination of Arabidopsis thaliana. The Arabidopsis treated with SAR supplemented with sulfuric and nitric acids, respectively, showed 28% and 30% decrease of shoot and root growth compared to the control plants, and also many necrotic spots on leaf surfaces after SAR treatment were observed. The shoot and root length for plants grown with nitric acid rain was 14% and 17% lower, respectively, compared to the control, whereas those grown with sulfuric acid rain was 24% and 25% lower than control plants. When Arabidopsis seeds were sown in distilled water, germination rate was 100% after 7 days. However, 80% in SAR medium supplemented with sulfuric and nitric acids, 88% in sulfuric acid rain medium and 93% in nitric acid rain medium. The germination abilities of seeds harvested from SAR supplemented with sulfuric and nitric acids, sulfuric acid rain, and nitric acid rain were 73%, 73% and 94%, respectively. Consequently, sulfuric acids showed more inhibitory effects than nitric acids on the growth of vegetative organs as well as germination rates in Arabidopsis.

• Journal of the Korean Applied Science and Technology
• /
• v.6 no.2
• /
• pp.21-28
• /
• 1989

1-naphthol-2-sulfonic acid and 1-naphthol-4-sulfonic acid were synthesized under the dissolution of 1-naphthol in 2-nitrotoluene with stirring 98.08-90％ sulfuric acid at $5-95^{\circ}C$ for 1-5 hours. As the reaction temperatures and the reaction time were raised, the yield of 2-sulfonate was decreased, while that of 4-sulfonate was increased. But we could not observe the tendency to the various reaction concentrations of sulfuric acids. The mixtures of two isomeric 1-naphtholulfonic acids in excess concentrated sulfuric acids was quantitatively determinded by using multicomponent spectrophotomeric analysis method on the basis of the ultraviolet absorption peak of the sulfonic acids. The standard deviation in this method was ${\pm}\;2.6$, and the above method seem to be rapid and accurate.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.6
• /
• pp.1998-2004
• /
• 2012

We carried out DFT calculations for monohydrated sulfuric and phosphoric acids. We are interested in clusters which differ in orientation of hydrogen atoms only. Such molecular complexes are close in energy, since they lie in the vicinity of the global minimum energy structure on the flat potential energy surface. For monohydrated sulfuric acid we identified four different isomers. The monohydrated phosphoric acid forms five different conformers. These systems are difficult to study from the theoretical point of view, since binding energy differences in several cases are very small. For each structure, we calculated harmonic vibrational frequencies to be sure that if the optimized structures are at the local or global minima on the potential energy surface. The analysis of calculated -OH vibrational frequencies is useful in interpretation of infrared photodissociation spectroscopy experiments. We employed four different DFT functionals in our calculations. For each structure, we calculated binding energies, thermodynamic properties, and harmonic vibrational frequencies. Our analysis clearly shows that DFT approach is suitable for studying monohydrated inorganic acids with different hydrogen atom orientations. We carried out MP2 calculations with aug-cc-pVDZ basis set for both monohydrated acids. MP2 results serve as a benchmark for DFT calculations.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.3
• /
• pp.255-265
• /
• 2021

Objectives: The purpose of this study is to analyze the exposure characteristics of inorganic acids. Methods: We analyzed exposure data (n = 363,146) for six inorganic acids (hydrogen fluoride, hydrogen bromide, hydrogen chloride, phosphoric acid, nitric acid, and sulfuric acid) collected between 2017 and 2019 in South Korea. Measurement characteristics and exposure levels (ELs) were analyzed by inorganic acid, industry category, enterprise size, and measurement year. Results: Measurement percentage dominated in time-weighted average (TWA, 91%) compared to short term exposure limit (STEL) and Ceiling. Most of the measurements (79.7%) were collected from the manufacturing category of industry. Medians of ELs were mostly low (≤3% of the threshold limit), with the exception of sulfuric acid (4.6% of TWA and 10.5% of STEL). The percentages of exceeding 1% of the occupational exposure limits (OELs) in TWA were relatively high for sulfuric acid (35.8%) and hydrogen chloride (16.5%) compared to the other acids (4.2%-6.6%). In addition, the percentages of exceeding 1% of OELs in STEL or Ceiling were higher for sulfuric acid (22.9%), hydrogen chloride (12.3%), and nitric acid (8.2%) compared to the other acids (1.2%-1.9%). The small-sized enterprises showed higher ELs in TWA; contrarily, the large-sized enterprises had higher ELs in STEL or Ceiling. Conclusions: The measurement characteristics and ELs identified in this study could be useful for establishing safety and health policies for inorganic acids.

• Journal of the Korean Applied Science and Technology
• /
• v.3 no.2
• /
• pp.29-34
• /
• 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($150^{\circ}{\sim}200^{\circ}$).

• Resources Recycling
• /
• v.30 no.3
• /
• pp.41-46
• /
• 2021

Methanesulfonic acid (MSA) can be considered effective in the leaching of metals because of its advantageous physical and chemical properties. The chemical reactivities of MSA and sulfuric acid were compared based on their structures and the dissolution data of Co and Ni metal. The inductive and resonance effects play a vital role in the chemical reactivities of these two acids. The dissolution percentages of Co and Ni in the sulfuric acid solution were higher than those in the MSA solution under the same experimental conditions. Considering the strong acidity of MSA and the high solubility of its metal salts, MSA can be employed as a leaching agent for the recovery of metals.

• Journal of Soil and Groundwater Environment
• /
• v.19 no.6
• /
• pp.6-12
• /
• 2014

We reviewed literature focusing on the amounts of domestic production, distribution, and consumption of strong acids and their spill cases. In particular, we investigated the chemistry and toxicity of four strong acids classified as "accident preparedness substances," including hydrochloric, nitric, sulfuric, and hydrofluoric acid. We recommend sulfuric and hydrofluoric acid as the chemicals of priority control based on the amounts used and toxicity. An advanced prevention/response system needs to be established along with an improved human and social infrastructure to prevent and efficiently respond to chemical accidents. Understanding the behavior and transport of spilled strong acids in the soil and groundwater environments requires a multi-disciplinary approach since they go through a variety of chemical and biogeochemical reactions with complex geomedia. However, no such research has been done in this area in Korea to the best of our knowledge. We expect the results of this study to contribute as basic data to future research.

• Economic and Environmental Geology
• /
• v.40 no.2 s.183
• /
• pp.141-151
• /
• 2007

This study was focused on iron removal from illite by L-ascorbic and oxalic acids. Iron has been shown as a secondary mineral such as iron oxides and hydroxides in illite ores. It is also known as a primary agent to degrade brightness index of the ores. Methods such as physical separation and chemical leaching with strong inorganic acids have been widely used to remove the iron from the ores. However, these methods are expensive and give rise to environmental problems. In this study, we examined an alternative method using solutions with different set of combination of sulfuric, hydrochloric, L-ascorbic, and oxalic acids. Compared to chemical treatments with only inorganic acids, our results demonstrate that an addition of L-ascorbic acid in inorganic acids results in decreasing both total concentrations of the inorganic acids and time for the treatments. The treatment with 0.15 M L-ascorbic acid and 0.25 M sulfuric acid in solution for 60 min significantly improved the brightness index from 42.4% to 74.4%. This improvement is similar to that of treatment with only 2.5 M sulfuric acid alone for 150 min. Mineralogical and chemical analyses were performed to compare the effect of acid leaching on illite powders. No obvious differences are observed in the mineralogical characteristics and particle size distributions of the samples. These results suggest that the treatment with the addition of L-ascorbic acid in sulfuric acid could effectively remove iron without modifying the physicochemical properties of illite under conditions used in this study.

• Journal of Life Science
• /
• v.13 no.1
• /
• pp.110-117
• /
• 2003

A thermotolerant yeast strain, Saccharomyces cerevisiae KNU5377 (abbreviated as KNU5377, was exposed to inorganic acids including sulfuric, nitric and hydrochloric acid. As a stressor, each inorganic acid is very easily dissociated in water, resulting in lowering environmental pH. When compared with a reference S. cerevisiae ATCC24858, KNU5377 could overcome such a severe condition containing a final 0.4% concentration of sulfuric acid or nitric acid to grow at the overnight culture, but this reference could not. Additionally, this strain showed a surprisingly strong tolerance by surviving despite of exposure to the regime of 0.35% of hydrochloric acid for over 90 min and also to 0.6% of sulfuric acid for 30 min. On the contrary, both strains could not survive against a final 0.45% concentration of nitric acid. This strain KNU5377 could produce ethanol of 3% in 2 days by using the fermentation medium containing a final 0.3% concentration of sulfuric arid. Moreover, change into a final 0.2% concentration of sulfuric acid caused this strain to enhance fermentation productivity up to about 4.5% even at $40^{\circ}C$. In exposure to a final 0.2% of sulfuric acid for 60 min, trehalose was most accumulated within 30 min in KNU5377, and this suggested a cellular defense system led by this disaccharide was profitable for this strain to lead to no morphological changes.