• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.651-654
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• 2016

A number of accidents relating to highly toxic hydrogen fluoride (HF) or hydrofluoric acid (HA) release have occurred over fast few decades in Korea. Thus, this study was conducted to investigate the fluoride (F) concentrations in paddy soil and brown rice from 2 different areas where the soils were exposed to HF and HA. In the first case, the HF leakage accident that occurred in 2012 affected the surrounding soils and crops and consequently, crops (rice) affected by HF were unavailable for forage even though F did not accumulate in the soil. For example, at the time of accident, F concentrations in brown rice samples were $33.0-1,395mg\;kg^{-1}$, while F concentrations in soil samples were $155-295mg\;kg^{-1}$ which were less than the Korean standard guideline values of $400mg\;kg^{-1}$. However, after a year, F concentrations in brown rice were observed below the detection limit ($1mg\;kg^{-1}$), although F concentrations in soils were similar with those in 2012. Also, large amounts of wastewater discharges containing HA occurred in 2013 and some agricultural soils exceeded the Korean standard guideline values for F ($400mg\;kg^{-1}$), but soil-plant F transfer was not observed. In conclusion, it was observed that soil to plant transfer of F is unlikely although HF and HA as gas or liquid form can cause direct damage to plants.

• Journal of Preventive Medicine and Public Health
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• v.26 no.4 s.44
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• pp.587-598
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• 1993

Hydrofluoric acid is one of the strongest irritating, corrosive and poisonous inorganic chemicals. Hydrofluoric acid burns are occurring with ever-increasing frequency due to the wide use of this acid in industries. Hydrofluoric acid burns are characterized by severe progressive tissue destruction and excruciating pain due to the unique properties of the freely dissolvable fluoride ion. The authors reviewed medical records of 32 cases (36 spells) of hydrofluoric acid burns which occurred in a hydrofluoric acid manufacturing factory from Sep. 1, 1990 to June 30, 1993. The results are as follows; 1. Eleven measurements of air concentrations of hydrofluoric acid by detection tube method from 1990 to 1992 were all below TLV (Department of Labor, R.O. K). 2. There were 19 cases (22 spells) of hydrofluoric acid burns which occurred during the study period among regular employees. The overall incidence density of hydrofluoric acid was 17.8 cases (20.6 spells) per 100 person-year. Incidence density was 19.0 cases (22.0 spells) per 100 person-year among male workers and there were no female cases. Incidence density was 32.9 cases (38.3 spells) per 100 person-year among production workers and 1.9 cases (1.9 spells) per 100 person-years among management workers with the difference being statistically significant (P<0.01). 3. Of 32 cases (36 spells) of hydrofluoric acid burns among workers who were regularly employed or temporarily employed, 26 spells (81.2%) were between age 20 to 39. In 15 spells(41.7%) burns occurred between 12:00 and 17:59 with 16 spells(44.3%) having arrived at hospital within 2 hours after the accident. 4. Of 36 spells, the main cause of hydrofluoric acid burns were by splashes (8 spells, 22.2 %). The most frequent site of burns were fingers and pain was the most frequent symptom. Thirty spells (83.3%) of the hydrofluoric acid burns were treated with local injection of antidote (calcium gluconate). Complete recovery without scarring were observed in most of the cases (34 out of 36 cases, 94.4%). The study results suggest that to prevent hydrofluoric acid burns, environmental control and the wearing of hydrofluoric acid resistant protective clothes and gloves are important. It is also stressed that establishment of an emergency management and a transfer system for hydrofluoric acid burn victims is necessary.

• Applied Chemistry for Engineering
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• v.2 no.1
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• pp.77-85
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• 1991

A series of samples having different $SiO_2/Al_2O_3$ ratio were prepared by treating hydrogen mordenites with boiling hydrochloric acid and with hydrofluoric acid. The acidities of these samples were measured by TPD of $NH_3$ and by pyridine adsorption using IR, and the catalytic activities and selectivities of isomerization were measured for the reaction of ortho-xylene. For the samples treated by boiling hydrochloric acid, the acidities decreased with the increasing $SiO_2/Al_2O_3$ ratio caused by the extraction of framework aluminum. The sample having the $SiO_2/Al_2O_3$ ratio or 22 showed better activity than the others. For the samples treated by hydrofluoric acid, the content of chemically binding fluorine increased with the increasing contact time of hydrofluoric acid solution. The catalytic activities decreased with the hydrofluoric acid treatment due to the decreased acid sites resulted from the extraction of aluminum and silicon as well as the hydroxyl group replacement by the fluoride ion. The slightly increasing catalytic activities, however, came from the newly created acid sites, due to the removal of surface silicon, having enhanced by the inductive effect of binding fluorin with further acid treatment.

• Archives of Plastic Surgery
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• v.35 no.4
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• pp.407-412
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• 2008

Purpose: Hydrofluoric acid(HF) is one of the most dangerous mineral acids with the dissociated fluoride ions. The initial corrosive burn is caused by free hydrogen ion, and the second and more severe burn is caused by penetration of fluoride ions into subcutaneous tissues. Silver is a cation producing dressing, an effective antimicrobial agent, but older silver-containing formulations are rapidly inactivated by wound environment, requiring frequent replenishment. But, $Acticoat^{(R)}$ is a relatively new form of silver dressing which helps avoid the problems of earlier agents. The aim of this study is to evaluate effects of $Acticoat^{(R)}$, silver-containing dressing on the treatment for HF injury wound. Methods: From september 2006 to september 2007, the study was carried out with 10 patients who had HF partial thickness burns. $Acticoat^{(R)}$ dressing and 10% calcium gluconate wet gauze dressings in 10 cases. As a principle, in the emergency treatment, partial or complete removal of the nail and early bullectomy along with copious washing with normal saline was done, depending on the degree of HF invasion of the wound. Wound was dressed with $Acticoat^{(R)}$ and 10% calcium gluconate solution. The effect of dressing was investgated by serial bacterial culture and wound exudates assessment. Results: We therefore reviewed 10 cases of HF-induced chemical burns and treatment principle. The 10 cases who came to the hospital nearly immediately after the injury healed completely without sequelae. Conclusion: As the industrial sector develops, the use of HF is increasing more and more, leading to increased incidences of HF-induced chemical burns. The education of patients regarding this subject should be empathized accordingly. In conclusion, $Acticoat^{(R)}$ dressing is a better choice for HF partial thickness burn injuries because of shorter healing time, less pain and more comfortable dressing.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.6.1-6.8
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• 2020

Objectives: This study investigated the effects of a hydrofluoric acid (HA; solution of hydrogen fluoride [HF] in water)-based smart etching (SE) solution at an elevated temperature on yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics in terms of bond strength and morphological changes. Materials and Methods: Eighty sintered Y-TZP specimens were prepared for shear bond strength (SBS) testing. The bonding surface of the Y-TZP specimens was treated with 37% phosphoric acid etching at 20℃-25℃, 4% HA etching at 20℃-25℃, or HA-based SE at 70℃-80℃. In all groups, zirconia primers were applied to the bonding surface of Y-TZP. For each group, 2 types of resin cement (with or without methacryloyloxydecyl dihydrogen phosphate [MDP]) were used. SBS testing was performed. Topographic changes of the etched Y-TZP surface were analyzed using scanning electron microscopy and atomic force microscopy. The results were analyzed and compared using 2-way analysis of variance. Results: Regardless of the type of resin cement, the highest bond strength was measured in the SE group, with significant differences compared to the other groups (p < 0.05). In all groups, MDP-containing resin cement yielded significantly higher bond strength values than MDP-free resin cement (p < 0.05). It was also shown that the Y-TZP surface was etched by the SE solution, causing a large change in the surface topography. Conclusions: Bond strength significantly improved when a heated HA-based SE solution was applied to the Y-TZP surface, and the etched Y-TZP surface was more irregular and had higher surface roughness.

• Korean Journal of Agricultural Science
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• v.42 no.3
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• pp.191-199
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• 2015

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.

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.449-461
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• 2013

As the hydrofluoric acid leak in Gumi-si, Gyeongsangbuk-do or hydrochloric acid leak in Ulsan, Gyeongsangnam-do demonstrated, chemical related accidents are mostly caused by large amounts of volatile toxic substances leaking due to the damages of storage tank or pipe lines of transporter. Safety assessment is the most important concern because such toxic material accidents cause human and material damages to the environment and atmosphere of the surrounding area. Therefore, in this study, a hydrofluoric acid leaked from a storage tank was selected as the study example to simulate the leaked substance diffusing into the atmosphere and result analysis was performed through the numerical Analysis and diffusion simulation of ALOHA(Areal Location of Hazardous Atmospheres). the results of a qualitative evaluation of HAZOP (Hazard Operability)was looked at to find that the flange leak, operation delay due to leakage of the valve and the hose, and toxic gas leak were danger factors. Possibility of fire from temperature, pressure and corrosion, nitrogen supply overpressure and toxic leak from internal corrosion of tank or pipe joints were also found to be high. ALOHA resulting effects were a little different depending on the input data of Dense Gas Model, however, the wind direction and speed, rather than atmospheric stability, played bigger role. Higher wind speed affected the diffusion of contaminant. In term of the diffusion concentration, both liquid and gas leaks resulted in almost the same $LC_{50}$ and ALOHA AEGL-3(Acute Exposure Guidline Level) values. Each scenarios showed almost identical results in ALOHA model. Therefore, a buffer distance of toxic gas can be determined by comparing the numerical analysis and the diffusion concentration to the IDLH(Immediately Dangerous to Life and Health). Such study will help perform the risk assessment of toxic leak more efficiently and be utilized in establishing community emergency response system properly.