Concentration determination of inorganic acids that do not absorb near-infrared (NIR) radiation through recognizing perturbed NIR water bands by them and investigation of accuracy dependency on their acidities

Chang, Kyeol,Shinzawa, Hideyuki,Chung, Hoeil Academic Press 2018 Microchemical Journal Vol. No.

<P><B>Abstract</B></P> <P>When near-infrared (NIR) spectroscopy is employed to determine the concentrations of inorganic acids in etchant solutions, the perturbation of the water bands resulting from the interactions with these acids is the only information available for analysis, since inorganic acids do not directly absorb NIR radiation. The water bands perturbed by dissociated hydronium ions and respective anions of the acids are not highly component-specific; therefore, characterization of their different interactions with water is necessary to understand the results of the multivariate quantitative analysis. For this purpose, the variations in the water bands that occurred with the inclusion of HCl, H<SUB>2</SUB>SO<SUB>4</SUB>, H<SUB>3</SUB>PO<SUB>4</SUB>, and HNO<SUB>3</SUB> were initially examined with the aid of a two-dimensional (2D) correlation analysis. According to this analysis, components with higher acidity, such as HCl, perturbed the water hydrogen bonding network more strongly. Also, the interactions between each dissociated ionic species and water molecules were somewhat dissimilar. This dissimilarity enabled differentiation between the four acids, although the spectral specificity was not high owing to the absence of direct NIR absorption. The accuracy in the determination of concentrations was better for components with lower p<I>K</I> <SUB>a</SUB>s, such as HCl and H<SUB>2</SUB>SO<SUB>4</SUB>, owing to their stronger perturbation of the water bands. When multicomponent samples were measured, the resulting accuracies deteriorated due to the further degradation in component specificity. Acquisition of reproducible spectra and avoidance of model over-fitting are critical for reliable NIR analysis of these types of samples, as the analyte-induced spectral features are broad and rather specificity-insufficient.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Inorganic acids (HCl, H<SUB>2</SUB>SO<SUB>4</SUB>, H<SUB>3</SUB>PO<SUB>4</SUB>, and HNO<SUB>3</SUB>) do not directly absorb NIR radiation. </LI> <LI> Varied NIR water band by dissociated H<SUB>3</SUB>O<SUP>+</SUP> and anion was used to determine concentration. </LI> <LI> 2D correlation analysis revealed that interaction of each acid with water molecule differed. </LI> <LI> Acidity governing strength of acid-water interaction directly influenced on accuracy. </LI> <LI> Multiple PCs were required in PLS modeling since diverse acid-water interactions occurred. </LI> </UL> </P>

무기산류에 대한 국내 작업환경측정 현황 분석

박해동 ( Hae Dong Park ),박승현 ( Seung-hyun Park ),정기효 ( Kihyo Jung ) 한국산업보건학회 2021 한국산업보건학회지 Vol.31 No.3

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.

Experimental work on leaching of printed circuit boards

( Srikanth Srivatsa ),( Sankar Bhattacharya ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Ground printed circuit boards (PCB) were pyrolysed to devolatilize the plastic components to fuel oils and gas for energy recovery. The by-product is a mixture of metals which is further treated with acids to dissolve the metals into leach liquor. A significant number of experiments were conducted with three inorganic acids and three organic acids using the metallic residues after pyrolysis. The major conclusions are: · The plastics can be easily converted into oil which can be used for on-site heat generation to support the pyrolysis process. The pyrolysis process can be accomplished in around 400℃ · The inorganic acids HCl, H₂SO₄ and HNO₃ are studied for the leaching of metals from the PCB metal mixture. · Cu, Al, Li, and Co can be easily extracted using either of the three acids. · Zn and Sn leaching has very low efficiency in all the three acids · Ni and Fe are poorly extracted into the leach liquor, with HCl showing relatively better extraction. · Au and Ag is easily extracted into HCl with efficiency reduced in HNO₃. However, the use of inorganic acids has its own difficulties in handling and disposal of waste liquid to meet environmental standards. Hence as alternative organic acids were used for the leaching of metals, organic acids are environmentally benign and bio-degradable. The organic acids tested for the purpose are citric acid, lactic acid and oxalic acid. The results suggest the following - · Oxalic acid has superior activity dissolving the majority of the metals present in the PCB mixture except for Sn and Fe. · 1M oxalic acid between 50-75 ℃ and for a duration of 2-4 h is sufficient to dissolve majority of the metals in the solution. The work is currently being scaled up.

고온 알코올발효 효모균주 Saccharomyces cerevisiae KNU5377의 무기산에 대한 스트레스반응 및 무기산 존재하의 알코올발효 생산능

윤혜선,백상규,김일섭,이인구,유춘발,진익렬 한국생명과학회 2003 생명과학회지 Vol.13 No.1

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. 고온내성을 가진 효모 균주, Saccharomyces cerevisiae KNU5377을 황산, 질산 그리고 염산에 노출시켰다. 스트레스 원으로써 무기산은 물에서 쉽게 해리되어 외부 산도를 떨어뜨린다. 여러 가지 무기산이 첨가된 조건에서 배양한 결과 KNU5377은 0.4%의 황산, 질산 농도에서 생육이 가능한 반면 대조 균주인 S. cerevisiae ATCC24858은 이 보다 낮은 농도인 0.3%가 생육의 한계였다. 더욱이 KNU5377은 0.35%의 염산에서 90분 이상, 0.6%의 황산에서는 30분 이상 생존이 가능한 높은 내성을 나타내었다. 반면에 두 균주 모두 0.45%의 질산에서는 생존하지 못하였다. 0.3%의 황산이 첨가된 조건에서 알코올 발효 시 KNU5377은 이틀 후 3%의 알코올을 생산하였다. 더욱이 0.2%의 황산 첨가와 동시에 $40^{\circ}C$ 고온에서도 4.5%의 높은 알코올 생산이 관찰되었다. 또한 황산 0.2%에 한 시간동안 노출시킨 뒤 세포내에 축적되는 trehalose의 농도를 측정한 결과, KNU5377에서는 30분내에 효과적으로 축적되었으며 동일한 스트레스 조건에서 전자현미경(TEM)을 통한 세포의 형태의 관찰 시 어떠한 변화도 나타나지 않았다.

Extraction and stripping of inorganic acids by Tris 2-ethylhexyl Amine

( Thi Hong Nguyen ),( Man Seung Lee ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.10

Abstract: After separation of valuable metals from the leaching solution of ores or secondary resources, the recovery of inorganic acids from the raffinate is important. Therefore, the possibility of recovering inorganic acids, such as HCl, H2SO4 and HNO3, by extraction with Tris 2-ethylhexyl amine (TEHA) was investigated. The solvent extraction reaction of acid by TEHA was identified by applying a slope analysis method to the extraction data. The extraction efficiency of the acids by TEHA was in the order HNO3 > HCl > H2SO4, which corresponds well to the variation in the electric charge densities of the anions of each acid. The loading capacity of TEHA for HNO3, HCl and H2SO4 was determined and the extraction behavior of the acid seemed to be affected by the acid concentration in the organic phase. It was possible to strip all the HCl and H2SO4 by using distilled water at room temperature, while the stripping percentage of HNO3 at the same conditions was very low.

참다래 수액을 이용한 기능성 음료개발

박용서,정순택 목포대학교 자연자원개발연구소 1999 자연자원연구 Vol.2 No.-

fructose, glucose, sucrose, galactose, manitol가 함유되어 있었는데 당의 대부분은 fructose였다. 수액내 주요 무기물은 칼슘, 칼륨 및 마그네슘으로 칼슘함량이 상대적으로 가장 높았다. 두 종에서 각각 10종의 아미노산이 함유되어 있었는데 이들 중 주요 아미노산은 glutamic acid, lysine 및 isoleucine이었는데 이 중 glutamic acid함량이 가장 높았다. 제조한 다래수액 음료수의 영양소함량에서 당은 21.2g, 칼슘 23.1mg, 카리 14.1mg, 아미노산 554..5mg, 비타민 C 15.0mg이었다. This experiment was conducted to develope a health drink by using xylem sap from 'Hayward' (Actinidia chinensis Planch) kiwifruit vines. Water content, soluble solids content, viscosity, and pH of the sap were 99.60%, 0.90%, 1.01% and 6.50%, respectively. Fructose was the highest content among free sugars followed by glucose, sucrose, galactose and manitol in 'Hayward'. The major in the sap were calcium, potassium, and magnesium and calcium was the dominant inorganic components among them. The sap of 'Hayward' was composed of 10 kinds of amino acids respectively, and major amino acid were glutamic acid, lysine, and isoleucine. Glutamic acid was the highest amino acid in the xylem sap. Nutrition facts of a developed drink(252mL) were 21.6g of sugar, 15mg of ascorbic acid, 23.1mg of calcium and 554mg of amino acids.

Formation and Characterization of Poly(acrylic acid) on Silica Particles Irradiated by γ-Ray Radiation

구준모,손대원,김진우,정회일,이영일,이휘건,이호익 한국고분자학회 2012 Macromolecular Research Vol.20 No.2

Organic/inorganic hybrid gels were directly prepared by polymerization on the peroxide surface of silica particles where the particle surface was irradiated by a 60Co γ-ray. These hydrogels have no residues of initiators or cross-linkers, so they can be used in biocompatible gel applications. Wide Raman spectroscopy was used to verify the interaction between the particles and poly(acrylic acid) (PAA). We observed that covalent bonds existing between the peroxide particles and acrylic acid, and the hydrogen bonds between the acrylic acids. For these studies,we prepared hydrogels by varying the particles’ concentration and the size of the silica particles to classify the number of reaction sites, which are the dominant factor for the chemical reaction between the silica particles and PAA.

도시공원녹지의 입지별 토양환경이 곰솔의 생육에 미치는 영향

김석규 東亞大學校 建設技術硏究所 2005 硏究論文集 Vol.29 No.1

The purpose of this study is to propose rational methods in order to maintain vegetation condition and soil environment based on the analysis of tree growth in relation to the soil environment, which is one of the most significant environmental factors on vegetation condition in urban parks and open spaces. From the result of soil environment analysis, it is found that trampling pressure from the users provides a great influence to the quality of soil environment. The soil on every study site had strong acidity. In particular, study sites around industrial district, central business district, and residential area showed extreme soil acidity. Therefore, soil management system is needed in urban parks and green spaces around those areas. locational tree vitality was bad where there was high user density, such as park entry and facility areas. Therefore, there is a strong relation between tree vitality and user density. Among tree vitalities classified by locations of park, one in the costal area was the highest. The tree vitality in the industrial area was the lowest. Therefore, soil condition and locational environment in the industrial area are highly related to the tree vitality. Among the factors, which affect tree vitality in different locations, inorganic content was found to be the main factor in all of the study sites. Inorganic content was an important factor to the tree vitality in study sites located in industrial and residential areas. In the study sites located in costal area, Soil acidity was found to be other important factors that affect tree vitality. Among various soil factors that affect tree vitality in parks, inorganic content and soil hardness were an important factor in the park entry and facility zone. Therefore, it is needed to maintain soil condition with different consideration depending on its main factors mentioned above.

Morphological and macrostructural studies of dog cranial bone demineralized with different acids

Gehan T. El-Bassyouni,Osiris W. Guirguis,Wafa I. Abdel-Fattah 한국물리학회 2013 Current Applied Physics Vol.13 No.5

Strong and weak acids were chosen for the bone decalcification process. Demineralization of dog cranial bone was carried out using 0.6 M concentration of either of hydrochloric, lactic or citric acid. Consequent morphologic changes were correlated with the developed chemistry, porosity and structure through XRD and FT-IR of the matrices. The dielectric permittivity, loss angle, relaxation dielectric loss as well as a.c. electrical conductivity as functions of frequency and temperature were measured. Zeta potential was evaluated at physiologic pH and temperature and correlated with the developed structures. The results prove lower dielectric properties of demineralized matrices compared to control and exhibited high dissipation of electric energy with more than one relaxation mechanism. This variation proves that the spectral behavior depended on the nature of the bone matrix which resulted from the phase compositions of bone and its crystallite size. The behavior of the obtained results is attributed to the differences of the demineralizing acids and their consequent actions on the matrices, i.e., the differences in the materials.

산해리도가 다른 무기산에 의한 토양 입자 표면 특성

이동성(Dong-Sung Lee),이교석(Kyo-suk Lee),신지수(Ji-Soo Shin),이재봉(Jae-Bong Lee),주리나(Ri-Na Joo),이명연(Myong-Youn Lee),민세원(Se-Won Min),정덕영(Doug-Young Chung) 충남대학교 농업과학연구소 2015 농업과학연구 Vol.42 No.3

We conducted this research to observe the changes of surface morphology and composition of clay minerals influenced by various concentrations of fluoric acid. Hydrofluoric acid (HA), a solution of hydrogen fluoride (HF) in water, is a colourless solution that is highly corrosive, capable of dissolving many materials, especially oxides. To do this, we treated several concentrations of HA on the ground soil samples collected from the agricultural experimental station located at Chungnam National University to observe the influence of fluoric acid on the changes of surface structures and elemental composition of clay particles. Generally, microscopic examination showed that the HA can not only attack an edge of clay particles but also start at any point where structural defects and weaknesses predisposed sites to acid. The orderly flake arrangement of clay minerals may reflect certain crystal symmetry elements. The ESEM-EDS results of element composition of clay particles influenced by HA indicated the changes of structures of clay minerals. It is also clear from the formation of etch figures and element composition of clay particles that the product layer at least partially dissolved or disintegrated in the presence of acid. Conclusively, the clay structures can be strongly influenced by concentrations of HA, resulting in changes of physical and chemical properties that can determine the behavior of solute transport as well as mobility of ions in soils.