• Journal of Environmental Health Sciences
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• v.46 no.6
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• pp.694-701
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• 2020

Objectives: The main purpose of this study is to evaluate heavy metal concentrations (Cd, As, Hg, Pb, Cr6+), particle size distribution, hydrochloric acid solubility, and parasite eggs in sand in five non-designated sandy beaches in Gyeonggi Province. Methods: The sampling sites are five non-designated Gyeonggi-do sandy beaches located in Ansan and Hwaseong. ICP-OES and UV, a Vibratory Sieve Shaker, and PCM were respectively used to analyze heavy metal concentrations, particle size distribution, and parasite eggs in the sand. Results: Heavy metals were detected within the beach's safety management standards and some of the detected As and Pb before and after beach opening were lower than one-quarter of the average value. In addition, the results of the T-test to confirm the As and Pb concentration changes before and after opening showed a significant difference in some beaches. The composition of sand was 86.53% according to the particle size distribution standard (2.0-0.02 mm), and the hydrochloric acid solubility was the highest at Gubongsolsup (4.9%) and the lowest at Bangameo-li (0.2%). Parasite eggs were undetected in all beach sand before and after opening. Conclusions: The safety of heavy metal concentrations in sandy beaches was secured in the selected five beaches in Gyeonggi Province. However, continuous efforts are required to make Gyeonggi-do's beaches suitable according to the Act on the Use and Management of Beaches.

• Animal Bioscience
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• v.36 no.3
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• pp.492-497
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• 2023

Objective: The objectives were to demonstrate that the nitrogen and energy in pig urine supplemented with hydrochloric acid (HCl) are not volatilized and to determine the minimum amount of HCl required for nitrogen preservation from pig urine. Methods: In Exp. 1, urine samples of 3.0 L each with 5 different nitrogen concentrations were divided into 2 groups: 1.5 L of urine added with i) 100 mL of distilled water or ii) 100 mL of 6 N HCl. The urine in open plastic containers was placed on a laboratory table at room temperature for 10 d. The weight, nitrogen concentration, and gross energy concentration of the urine samples were determined every 2 d. In Exp. 2, three urine samples with different nitrogen concentrations were added with different amounts of 6 N HCl to obtain varying pH values. All urine samples were placed on a laboratory table for 5 d followed by nitrogen analysis. Results: Nitrogen amounts in urine supplemented with distilled water decreased linearly with time, whereas those supplemented with 6 N HCl remained constant. Based on the linear broken-line analysis, nitrogen was not volatilized at a pH below 5.12 (standard error = 0.71 and p<0.01). In Exp. 3, an equation for determining the amount of 6 N HCl to preserve nitrogen in pig urine was developed: additional 6 N HCl (mL) to 100 mL of urine = 3.83×nitrogen in urine (g/100 mL)+0.71 with R² = 0.96 and p<0.01. If 62.7 g/d of nitrogen is excreted, at least 240 mL of 6 N HCl should be added to the urine collection container. Conclusion: Nitrogen in pig urine is not volatilized at a pH below 5.12 at room temperature and the amount of 6 N HCl required for nitrogen preservation may be up to 240 mL per day for a 110-kg pig depending on urinary nitrogen excretion.

• Analytical Science and Technology
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• v.5 no.3
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• pp.277-283
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• 1992

Acid effects on the ICP-AES signals are studied as the concentrations of nitric acid, hydrochloric acid, sulfuric acid, and 1:1 mixture of nitric acid and hydrochloric acid are changed. Almost all analyte signals are depressed. The extent of the depression due to the pressence of the acids became to be pecular when the acid concentration was over 1%. Among the acids used, the suppression due to sulfuric acid is most severe and unexpectable. The ratios of the analyte signal to Ar signal and the Mg II signal to Mg I signal are measured as the concentration of the acids changed. In this study, it is proved that the main reason of the signal reduction is the change in the nebulization efficiency, for example, droplet size distribution, viscosity and surface tension variation, not the alteration of plasma excitation characteristics. There was no relationship found between ionization potential and analyte signal reduction in ICP-MS.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.1
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• pp.1-11
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• 2011

Tetraethoxysilane(TEOS) as a silica precursor and hydrochloric acid as an acid catalyst have been used in a surfactant-template synthesis of micrometer-sized mesoporous silica microspheres based on the macroemulsion technique. Increase in the concentration of tetraethoxysilane of the reaction mixture has a serious destructive effect on the particle shape and pore structure. As the acid concentration increases, relatively small microspheres are formed without destroying their spherical morphology of the particles as well as the pore structures. However, due to the attractive interaction between particles in an acidic condition, strong silica agglomerates are formed, and therefore are subject to a post-ultrasonic treatment to separate into an individual single particle.

• Journal of the Korean Chemical Society
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• v.20 no.6
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• pp.469-478
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• 1976

Clinoptilolite zeolite samples were treated with hydrochloric acid, sulfuric acid and phosphoric acid of different strength and the adsorption characteristics and crystal structures of the original and acid-treated clinoptilolites were studied. By treating with hydrochloric acid, the adsorbed amount increased to 5-fold for nitrogen, to 3-fold for benzene, but for methanol no significant change was observed. As acid strength increased further, there were declines both in adsorption capacity and crystallinity. The results showed that the increase of adsorbed amount was caused by the rearrangement of the pore entrance and cation exchange. A method for determination of clinoptilolite content in natural mineral based on benzene adsorption on acid-treated sample is proposed. By this method, the original sample used in this study was found to contain approximately 40% of clinoptilolite. Using pulse technique in micro-catalytic reactor system, the catalytic activities of hydrochloric acid-treated clinoptilolites in cumene cracking and toluene disproportionation reactions were measured. For cumene cracking reaction, the maximum conversion was observed for the 0.5 N hydrochloric acid-treated sample. It is instructive to note that the maximum benzene adsorption was also observed for the sample treated with 0.5 N HCl. This suggest that the conversion rate was determined mainly by the rate of transport of reactants and the products through the pore structure. In the toluene disproportionation reaction, the same trend was observed. But the rate of deactivation was high for samples with strong acid sites. Since catalyst having higher activity was deactivated more easily, the conversion maximum was shifted to the sample treated with higher concentration of acid, -1N. The catalytic activity of $Ca^{2+} and La^{3+} ion exchanged samples for the toluene disproportion was much lower than that of acid-treated samples. Introduction of Ca^{2+} and La^{3+}$ into the pore structure apparently decreases the effective pore diameter of acid-treated clinoptilolite thus limiting the diffusion of reactants and products.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.291.2-291.2
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• 2016

3D semiconductor material of silicon that is used throughout the semiconductor industry currently faces a physical limitation of the development of semiconductor process technology. The research into the next generation of nano-semiconductor materials such as semiconductor properties superior to replace silicon in order to overcome the physical limitations, such as the 2-dimensional graphene material in 2D transition-metal dichalcogenide (TMD) has been researched. In particular, 2D TMD doping without severely damage of crystal structure is required different conventional methods such as ion implantation in 3D semiconductor device. Here, we study a p-type doping technique on tungsten diselenide (WSe2) for p-channel 2D transistors by adjusting the concentration of hydrochloric acid through Raman spectroscopy and electrical/optical measurements. Where the performance parameters of WSe2 - based electronic device can be properly designed or optimized. (on currents increasing and threshold voltage positive shift.) We expect that our p-doping method will make it possible to successfully integrate future layered semiconductor devices.

• Korean Journal of Metals and Materials
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• v.46 no.4
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• pp.227-232
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• 2008

Solvent extraction reaction of cobalt by Alamine336 from strong hydrochloric acid solution was identified by analyzing the solvent extraction data reported in the literature. Analysis of the data by graphical method revealed that Alamine336 took part in the solvent extraction reaction as a monomer in the concentration ranges, [Co(II)] : 0.0169 - 0.102 M, [Alamine336] ; 0.02- 1.75 M, and [HCl ] : 5 - 10 M. The following solvent extraction reaction and equilibrium constant was obtained from the experimental data by considering the activity coefficients of chemical species present in the aqueous phase. $Co^{2+}+2Cl^{-}+R_3NHCl_{org}=CoCl_3\;R_3NH_{org}$, $K_{ex}=2.21$ The distribution coefficients of cobalt predicted in this study agreed well with those reported in the literature.

• Textile Coloration and Finishing
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• v.11 no.2
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• pp.55-63
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• 1999

The purpose of this study was to investigate the purification of chitin and chitosan for textile finishing agent from crab shell. Weight loss rate(removing Ca and protein), degree of deacetylation, solubility and MIC(Minimum growth inhibitory concentration) value of chitosan and molecular weight of the treated crab shell were measured. The results of this study were as follows : 1) Weight loss rate(removing Ca) of crab shell treated with HCI increased with the concentration of HCI and treatment time, but it became constant over 60 min. of treatment time. 2) Weight loss rate(removing protein) of crab shell treated with NaOH(0.5N∼2N) increased with the concentration of NaOH and treatment temperature and time, but it became constant above loot of temperature and over 200 min. of treatment time. 3) Degree of deacetylation of chitin treated with NaOH increased with the concentration of NaOH(40∼60％), but molecular weight decreased and thus MIC value increased. 4) Concentration of acetic acid should be above 0.3％ to dissolve chitosan easily. Solubility for chitosan was the highest with formic acid, and the next was acetic acid, hydrochloric acid, lactic acid and sulfuric acid in order.

• Resources Recycling
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• v.20 no.2
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• pp.60-66
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• 2011

Solvent extraction experiments were carried out to recover and separate Ru(III) from aqueous hydrochloric acid media using TBP and Cyanex923. The efficiency of the extraction was studied under various experimental conditions, such as concentration of HCl and NaCl, concentration of extractant in the organic phase and temperature. The extraction behavior of metal impurities, such as Pt, Bi, Sn, Fe, Pb and Cu in mixed solutions was examined. From the experimental studies, it was found that the Cyanex923 resulted in higher extraction percentage of Ru than TBP. However TBP was more effective for the separation of Ru and Pt, Bi, Sn in mixed solutions than Cyanex923.

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.929-935
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• 2010

The solvent extraction behavior of Sn(IV) from hydrochloric acid was investigated using Alamine336 (Tri-n-cotylamine) as an extractant. The experimental parameters of the concentration of the HCl solution, chloride ions, extractant, and Sn(IV) were assessed. The results showed that the extraction percentage of Sn(IV) was more than 95% in our experimental range and was only slightly affected by the HCl concentration. The extraction reaction of Sn(IV) by Alamine 336 from the chloride solution was identified as follows: $SnCl_6{^{2-}}+2R_3NHCl_{(org)}=(R_3NH)_2SnCl_{6(org)}+2Cl^-$ and $K=6.3{\times}10^4$. Stripping experiments of Sn(IV) from the loaded organic phase were done by using several stripping agents. A stripping percentage of 90% was obtained with a 2.0 M NaOH solution.