본 연구에서는 열유도상분리법으로 제조한 polyvinylidene fluoride (PVDF) 중공사막의 오염성과 화학적 세척에 대한 실험을 진행하였다. 오염수는 소 혈청 단백질(bovine serum albumin, BSA)과 카올린(kaolin)을 이용해 제조하였으며, 차아 염소산나트륨(NaOCl), 구연산(citric acid), 황산(H2SO4)으로 화학적 세척을 진행한 후 뒤 표면 전하 분석기, 주사전자현미경 (scanning electron microscope, SEM) 그리고 에너지 분산 X선 분광법(energy dispersive X-ray spectroscopy, EDX)을 통해 세 척 효율을 평가하였다. PVDF 분리막은 높은 내화학성과 열적 안정성을 가지는 분리막으로 화학적 세척을 진행한 결과 가장 좋은 효율은 차아염소산나트륨으로 세척한 것으로 그 결과 투과도는 793.2 L/(m2.h.bar)로 초기 투과량인 945.3 L/(m2.h.bar) 값과 비교하였을 때 약 84% 회복률을 보여주었다. 이는 수처리 공정에서의 막 오염 방지 및 세척의 중요성을 제시한다.

The electrochemical properties of a CFX cathode were improved by defluorination of the surface with a N2 plasma and using a silica wafer. Compared to the N2 plasma treatment alone, when the CFX and silica were reacted together, the C-F bonds were modified and the surface was etched efficiently, so defluorination was enhanced. An electrochemical analysis confirmed that Half-cells prepared by treating CFx and silica with nitrogen plasma exhibited a capacity of about 400 mAh/g at 5C. In addition, it was confirmed that the loss of charge transfer was reduced by up to 71% compared to that for pristine CFX. As shown by a GITT analysis, when the CFx and silica were treated with N2 plasma together, the ion conductivity gradually increased due to a decrease in the ion diffusion barriers and the formation of a carbon layer. Therefore, this is a simple and effective way to improve the conductivities of CFX cathode materials with the energy of a N2 plasma and the silica-fluorine reaction.

Large-area porous carbon is easily produced for supercapacitors from polyvinylidene chloride (PVDC) and polyvinylidene fluoride (PVDF) precursors, composed of carbon backbone and attached heteroatoms. The released heteroatoms during pyrolysis leave the porous carbon. This study explored the activation of both precursors using chemical agents (ZnO, Mg(OH)2, and KOH) to develop carbon with multiple micropores and mesopores. The activation process and relevant precursors were studied to implement synthesized porous carbon as an electrode in supercapacitors. During the activation of PVDC-resin, ZnO served both as templates and activating agents, while Mg(OH)2 served only as a template, and KOH served as an activating agent. For activation of PVDF, ZnO acted as a template and activating agent, whereas Mg(OH)2 and KOH impeded activation owing to side reactions. Therefore, with the above chemical agents, PVDC-resin was converted to carbon with a higher surface area than PVDF. The porous carbon produced using PVDC-resin with KOH had the highest specific capacitance of 137 F g− 1 and rate performance of 79% at 50 mV s− 1 (vs. 5 mV s− 1) owing to the successful creation of micropores and mesopores. This study identifies optimal conditions for synthesizing porous carbon using polymer precursors and chemical agents for supercapacitors.

Porous graphene oxide (P-GO) was successfully synthesized by using a simple glucose mediated hydrothermal method form prepared graphene oxide (GO). Then the P-GO was characterized by X-ray Powder Diffraction (XRD), Fourier-Transform Infrared (FITR), Raman, Brunauer–Emmett–Teller (BET), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) analysis to determine the crystallinity, surface functionality, surface defect, surface area and porous nature of the material. For the comparative properties studies with P-GO, the synthesised GO was also characterised using the aforementioned analytical techniques. The formation of macroporous 2D sheet-like structure of P-GO with pore size diameters of 0.2–0.5 μm was confirmed by FESEM and TEM images. The surface area of P-GO was found to be 1272 m2/ g which is much higher compare to GO (i.e., 172 m2/ g) because of porous structure. P-GO was used for the adsorptive removal of F− ions from water using batch adsorption method. The highest adsorption occurs in the pH range of 5–7 with maximum adsorption capacity of 1272 mg/g. The experimental data revealed that the adsorption process obeys Langmuir monolayer isotherm model. The kinetic analysis revealed that the adsorption procedure is extremely rapid and mainly fit to the Pseudo-second-order (PSO) model. The effect of co-existing ions on fluoride adsorption capacity by P-GO decreases in the following order: PO4 3− > CO3 2− > SO4 2− > HCO3 − > NO3 − > Cl−. The mechanism of adsorption of fluoride onto the P-GO surface includes electrostatic interactions and hydrogen bonding.

BaTiO3-Poly vinylidene fluoride (PVDF) solution was prepared by adding 0~25 wt% BaTiO3 nanopowder and 10 wt% PVDF powder in solvent. BaTiO3-PVDF film was fabricated by spreading the solution on a glass with a doctor blade. The output performance increased with increasing BaTiO3 concentration. When the BaTiO3 concentration was 20 wt%, the output voltage and current were 4.98 V and 1.03 μA at an applied force of 100 N. However, they decreased when the over 20 wt% BaTiO3 powder was added, due to the aggregation of particles. To enhance the output performance, the generator was poled with an electric field of 150~250 kV/cm at 100 °C for 12 h. The output performance increased with increasing electric field. The output voltage and current were 7.87 V and 2.5 μA when poled with a 200 kV/cm electric field. This result seems likely to be caused by the c-axis alignment of the BaTiO3 after poling treatment. XRD patterns of the poled BaTiO3-PVDF films showed that the intensity of the (002) peak increased under high electric field. However, when the generator was poled with 250 kV/cm, the output performance of the generator degraded due to breakdown of the BaTiO3-PVDF film. When the generator was matched with 800 Ω resistance, the power density of the generator reached 1.74 mW/m2. The generator was able to charge a 10 μF capacitor up to 1.11 V and turn on 10 red LEDs.

The utilization of methyl bromide (MB) for quarantine purposes has been hampered by its designation as an ozone-depleting substance under the Montreal Protocol. The International Plant Protection Convention's (IPPC) call for alternatives to MB and a reduction in its usage. There is an urgent need to explore and implement substitutes. Despite some substitute agents like EDN being developed for wood, EDN has been limited due to various factors such as occupational risks. This study focuses on evaluating the efficacy of Sulfuryl Fluoride (SF) as a viable alternative fumigant against Reticulitermes speratus, one of major wood destroying pests. Experimental trials conducted at ambient temperature (23°C) revealed promising results, with SF demonstrating LCT50 and LCT99 values of 30.87 mg·h/L and 42.53 mg·h/L, respectively. Under low-temperature conditions (5°C), SF remained effective but with slightly higher LCT50 and LCT99 values of 151.62 mg·h/L and 401.90 mg·h/L, respectively. The penetration test, conducted using R. speratus-infested pine wood cubes, further highlighted SF's efficacy, with LCT50 and LCT99 values of 31.59 mg·h/L and 53.34mg·h/L at 23°C, indicating powerful penetration capabilities. When tested at a loading ratio of 90% (v/v) at 5.0mg/L for 24 hours in a 500L chamber as a middle-scale trial, SF achieved a 100% mortality, showing its potential as a suitable replacement for MB. These findings suggest that SF could open new markets as an MB substitute and enhance safety at quarantine sites when applied to imported and exported timber.

Research on alternative fumigants to replace methyl bromide (MB), a harmful ozone-depleting substance and highly toxic pesticide, began in 2007. Initial tests focused on using ethyl formate for fruits and EDN for wood. Subsequently, alternative techniques were developed for a total of 94 plant types using ethyl formate, EDN, and phosphine, demonstrating Korea's superior performance compared to other countries, especially in practical applications. However, when it comes to wood products, the primary users of methyl bromide, EDN is scarcely used due to concerns about worker safety. An emerging alternative to MB is sulfuryl fluoride (SF), widely employed in North America to control wood-damaging pests like termites. SF's advantages include a lower boiling point and higher vapor pressure, making it effective against wood pests. Yet, certain bark beetle eggs require higher doses and longer treatment periods, resulting in established international standards (e.g., 120g/m3 for 48 hours at 20℃), posing challenges for field applications. Recently, the APQA initiated basic research to apply SF to wood. They are assessing SF's effectiveness against various wood-destroying pests, including termites, bark beetles, and long horn beetles, while also evaluating the feasibility of mixed treatments to reduce dosage. Once SF fumigation standards are established, it is expected to significantly reduce methyl bromide use in commonly used wood types, contributing to ozone layer protection and enhancing fumigation work safety.

The facile production of high-purity mesophase pitch has been a long-standing desire in various carbon industries. Recently, polymer additives for mesophase production have attracted much attention because of their convenience and efficiency. We propose polyvinylidene fluoride (PVDF) as a strong candidate as an effective additive for mesophase production. The mesophase content and structural, chemical, and thermal properties of pitches obtained with different amounts of added PVDF are discussed. The influence of PVDF decomposition on mesophase formation is also discussed. We believe that this work provides an effective option for mesophase pitch production.

This study presents the data analysis results of groundwater chemistry and the occurrence of fluoride in groundwater obtained from the groundwater quality monitoring network of Korea. The groundwater data were collected from the National Groundwater Information Center and censored for erratic values and charge balance (±10%). From the geochemical graphs and various ionic ratios, it was observed that the Ca-HCO3 type was predominant in Korean groundwater. In addition, water-rock interaction was identified as a key chemical process controlling groundwater chemistry, while precipitation and evaporation were found to be less important. According to a non-parametric trend test, at p=0.05, the concentration of fluoride in groundwater did not increase significantly and only 4.3% of the total groundwater exceeded the Korean drinking water standard of 1.5 mg/L. However, student t-tests revealed that the fluoride concentrations were closely associated with the lithologies of tuff, granite porphyry, and metamorphic rocks showing distinctively high levels. This study enhances our understanding of groundwater chemical composition and major controlling factors of fluoride occurrence and distribution in Korean groundwater.

In this study, the physicochemical characteristics and fluoride adsorption capacity of the bone char pyrolyzed at different temperatures; 200℃, 300℃, 350℃, 400℃, 500℃, 600℃, and 700℃ were investigated. Analytical studies of the synthesized bone char including; SEM-EDS, XRD, BET and FT-IR, showed the presence of hydroxyapatite(HAP), which is the main substance that adsorbs fluoride from aqueous solutions containing high fluoride concentrations. Bone char pyrolyzed from 350∼700℃ specifically revealed that, the lower the temperature, the higher the fluoride adsorption capacity and vice versa. The loss of the fluoride adsorption function of HAP (OH- band in the FTIR analysis) was interpreted as the main reason behind this inverse correlation between temperature and fluoride adsorption. Bone char produced at 350°C hence exhibited a fluoride adsorption capacity of 10.56 mgF/g, resulting in significantly higher adsorption compared to previous studies.

본 연구에서는 강유전성 고분자를 이용하여 제작된 100 nm 이하 두께를 가지는 박막형 커페시터의 측정 주파수에 따른 분극 반전 특성을 측정, 분석하였다. 고정된 박막 두께에 대해, 인가되는 최고 전기장의 세기가 증가할수록 더 높은 항전계에서 분극 반전이 발생되었다. 고정된 최고 전기장에 대해, 박막의 두께에 무관하게 같은 항전계에서 분극 반전이 발생되었다. 모든 측정에서 로그스케일 전기장 및 로그스케일 주파수의 관계에서 약 0.12 ± 0.01의 비례 상수를 보였다. 결과적으로, 강유전체 고분자 커페시터가 40 nm 두께까지는 size effect 없이 일정한 분극 반전 특성을 보였다. 본 연구는 저전압 동작 고분자 메모리 소자의 동작 예측에 유용할 것이므로 저전압에서 동작 가능한 고분자 메모리 소자의 가능성을 보여준다.

NaF를 용량별로 Sprague Dawley계 수컷 흰쥐에 경구 투여했을 때, 체중 및 장기 중량, 혈청 지질성분, 혈당 및 단백질 함량과 기본식이를 급여한 대조군인 BD군을 비롯하여 기본식이에 농도별 NaF를 경구 투여한 군들로 나누어 5주간 실험 사육한 결과, 흰쥐의 체중 증가량은 NF25군, NF30군 및 NF50군에서 대조군보다 유의적인 차이를 보이며 높게 나타났다(p<0.05). 각 장기무게에서의 변화 중 간장과 심장에서는 대조군에 비해 NaF 경구 투여 군에서 낮게 나타나는 경향이 관찰 되었으며(p<0.05), 폐, 뇌, 신장, 비장 및 고환에서의 각 군의 장기무게는 유의적인 차이가 없었다(p<0.05). 혈청 중 총 콜레스테롤, LDL 콜레스테롤, 유리 콜레스테롤, 중성지방, 인지질, 혈당 농도는 대조군보다 NaF 경구 투여한 군에서 NaF 농도가 높아짐에 따라 증가하였고, HDL 콜레스테롤 농도는 NaF 농도에 따라 점차 감소하는 것으로 관찰되었다. 혈청 중 총 단백질은 NF50군에서 유의적인 차이를 보이며 낮게 나타났으나 나머지 군에서 유의적 차이가 없는 것으로 나타났으며(p<0.05), 알부민 농도와 글로불린 농도 또한 NF50군에서 가장 낮은 결과치로 나타났다. 반면 알부민/글로불린 비는 NaF 농도와 관계가 없는 것으로 관찰되었다. 따라서 일정 이상 농도의 NaF 경구 투여는 흰쥐의 체중 및 지질성분을 증가시키는 것으로 판단되며, 이는 비만 및 이상지질혈증을 초래할 수 있을 것으로 추정된다.