Synthesis and amine-grafted on mesoporous silica, SBA-15

류성철,김지윤,심왕근,문희 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

Conventional adsorbents such as chitosan, pumice and activated carbons, have been used in removing nitrates from water ways. However, in general, it falls short of expectations when they are applied in actual field because of their low adsorption capacities for nitrates. Therefore it is important to make high-quality adsorbents that have not only physical and chemical stability but also high adsorption capacity. It has been known that mesoporous silica materials such as SBA-15 and MCM-48 can give a solution to overcome demerits of existing absorbents, especially when they are grafted with amines. In this work P123, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), was used as a structure directing agent and TEOS, tetraethyl orthosilicate, was used as silica source for the synthesis of SBA-15. The SBA-15 was also post-grafted with a grafting agent, 3-aminopropyltriethoxysilane (APTES). All silica samples obtained were carefully characterized using XRD, SEM and TEM images to check their structure. Whether the grafting was done well or not was checked by FT-IR spectra. The specific surface area and pore size distribution of the mesoporous silica materials were measured from nitrogen adsorption isotherms. Furthermore kinetic and equilibrium experiments for the removal of nitrates were carried out and it was proven that the grafting of the SBA-15 greatly enhances the adsorption capacity of pristine SBA-15.

Synthesis of mesoporous silica SBA-15 in a micro-flow reactor

류성철,심왕근,김도형,문희 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

In general, mesoporous silica materials have been synthesized in batch reactors by hydrothermal reaction. In the batch system, the reaction time is too long and it is hard to get homogeneous products. On the other hand, the reaction occurs in micrometer-size channels of a micro-flow reactor. For that reason, it can reduce the reaction time by 1/100 due to easy heat/mass transfer. Also, it can produce good products with high quality and the mount of mesoporous silica materials can be prepared in large scale using by multiple parallel flow reactors. In this work, SBA-15 has been made in a flow reactor to overcome disadvantages in the batch reactor. There are many conditions to be monitored such as temperature, flow rate and reaction time. The optimum condition was found in making SBA-15 in a droplet through the flow reactor. The synthesized silica materials were characterized by XRD, BET and TEM. Furthermore, they were compared with the SBA-15 which was prepared in the batch reactor.

연구에 기반을 둔 과학 교수학습 자료의 개발과 현장 적용

류성철 한국과학교육학회 2008 한국과학교육학회 학술발표 및 세미나집 Vol.2008 No.-

Removal of nitrate using amine-grafted and magnetized mesoporous silica material, SBA-15

류성철,( Seenivasan Selvaraj ),심왕근,문희 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Mesoporous silica materials such as SBA-15 and MCM-48 have been used in removing nitrates from water bodies. Because of their chemical stability, their adsorption capacities for nitrates are not so high. In most adsorption applications, the important factors are not only their high adsorption capacity but also the reusability of adsorbent materials. Therefore the pristine silica materials are amine-grafted and magnetized to overcome these limitations. In this work, P123, poly(ethylene glycol)- block-poly(propylene glycol)-block-poly(ethylene glycol), was used as a structure directing agent and TEOS, tetraethyl orthosilicate, was used as a silica source for the synthesis of SBA-15. The magnetization of SBA-15 was carried out by introducing 0.5 g of SBA-15 into a solution of 1.34 g Fe(NO3)3ㆍ9H2O and methanol, drying the mixture in an oven at 85°C and then slowly reacting the resultant powder with propionic acid at 105°C. The final product was thermally treated with a rate of 1°C/min to 300°C and then kept it for 5 hr. It was proven that the final silica material is a good recyclable adsorbent for removing and recovering nitrates from water streams.

Removal of nitrates using amine grafted and magnetized SBA-15

류성철,심왕근,문희 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

To remove nitrates from water bodies, SBA-15 has been used. However, its adsorption capacity for nitrates is not so high because of its chemical stability. And its reusability is also an important factor. To overcome these limitations, the SBA-15 has been modified such as amine-grafting and magnetization. In general, APTES, aminopropyltriethoxysilane, has been used as a grafting material to overcome low adsorption ability for nitrates. In many references, 16 mmol of APTES was used to enhance the adsorption capacity. But in this work, various amounts of APTES were tried to find the best amount of the grafting agent. The magnetization of SBA-15 was also carried out by introducing 0.5 g of SBA-15 and various amounts of Fe(NO3)3·9H2O. And then the best magnetized SBA-15 was grafted using the best amount of APTES. It was proven that the grafted and magnetized SBA-15 sample has not only a good recyclability but also high adsorption capacity to remove and recover nitrates from water streams.

비파괴검사 데이터의 머신러닝을 이용한 알루미늄 합금의 강도 추정

류성철,장경영 한국비파괴검사학회 2023 한국비파괴검사학회지 Vol.43 No.3

The increasing demand for lightweight aluminum alloys in advanced industrial products has necessitated the development of monitoring techniques for material strength using non-destructive testing (NDT) methods to ensure quality control. In this study, a machine learning model was developed to estimate the strength of aluminum alloys using NDT parameters known to be related to material strength, such as ultrasonic longitudinal/transverse velocity, attenuation coefficient, nonlinearity parameter, and eddy current electrical conductivity. The training data set consisted of NDT parameters obtained from more than 400 specimens with diverse strength distributions, along with tensile test data. A dedicated automated measurement system was employed to enhance the reliability of NDT parameter measurements. The estimated strength achieved more than 90% accuracy when a ±20 MPa interval accuracy was applied to the ground-truth strength. As data accumulation continues in the future, the performance of the proposed model is expected to improve further. Considering that destructive tensile tests possess an uncertainty of approximately 10%, the proposed technique offers an alternative to destructive testing, thereby establishing itself as a promising technology. 첨단 산업 제품의 경량화를 위한 알루미늄 합금의 수요가 늘어가면서 품질 관리를 위해 비파괴검사기법을 이용한 재료강도의 전수 모니터링 기술이 필요하게 되었다. 이를 위해서 본 연구에서는 재료의 강도와 관련이 있다고 알려진 비파괴검사 파라미터들인 초음파 종/횡파속도, 감쇠계수, 비선형 파라미터, 와전류전기전도도를 입력파라미터로 사용하여 알루미늄 합금의 강도를 추정할 수 있는 머신러닝 모델을 개발하였다. 학습을 위한 데이터셋은 다양한 강도분포를 갖도록 제작한 400여 개의 시편으로부터 얻은 비파괴검사 파라미터와 인장시험 데이터로 구성되었다. 특히 비파괴검사 파라미터의 측정에는 신뢰성을 높이기 위해 전용으로 개발된 자동화 측정시스템을 이용하였다. 학습결과 추정된 강도는 실제 강도와 ±20 MPa의 구간 정확도를 적용할 때 90% 이상의 정확도를 얻을 수 있었다. 향후 데이터의 축적이 지속되면 성능은 더욱 향상될 수 있을 것으로 기대되며, 이는 파괴 인장시험의 불확도가 10% 수준임을 감안할 때 제안하는 기술이 파괴시험을 대체할 수 있는 충분히 가능성이 높은 기술임을 입증한다.

Synthesis of mesoporous silica SBA-15 using a dropwise flow reactor

류성철,이종환,문희 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.9

Generally, mesoporous silica materials, such as SBA-15, are hydrothermally synthesized in batch reactors. We synthesized SBA-15 in a dropwise flow reactor, which has several merits, such as short reaction times, continuous operation, and easy scale-up. The reaction system had three parts: a mixer and two reaction channels, one operated at a low temperature of 35 oC for the self-assembly of 2D hexagonal silica structures, and the other operated at a high temperature of over 80 oC to increase the stability of the silica structure. Two different operating schemes were used to mix the two immiscible reactant streams, one with a magnetically driven active mixer and the other with a direct supply of premixed reactants. The dropwise flow reactor with the active mixer instead of the low-temperature reaction channel produced fractured silica particles in the final product. However, when a premixed solution under hydrolysis conditions was employed, the synthesis of mesoporous silica SBA-15 was successful within 2.5 h in the dropwise flow reactor, showing close physical properties to the reference SBA-15 sample obtained in a conventional batch reactor.

초음파 및 와전류 데이터 기반 재료강도 비파괴평가 솔루션 개발

류성철(Seong-Cheol Ryu),박성현(Seong-hyun Park),장경영(Kyung-Young Jhang) 한국비파괴검사학회 2022 한국비파괴검사학회 춘계학술대회 초록집 Vol.2022 No.5

초음파 및 와전류 데이터기반 재료강도 비파괴평가 솔루션 개발 Ⅲ

류성철(Seong-Cheol Ryu),장경영(Kyung-Young Jhang) 한국비파괴검사학회 2023 한국비파괴검사학회 춘계학술대회 초록집 Vol.2023 No.5

Synthesis of SBA-15 in a flow-reactor

이종환,류성철,문희 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

SBA-15, one of mesoporous silica materials, was synthesized from tri-block-copolymer (P123) as a template, tetraethyl orthosilicate (TEOS) as a silica precursor, and hydrochloric acid as a catalyst in a small-size flow reactor. The experimental variables for the reaction were pH (1 - 3), reaction time, temperature, and concentration of P123. The synthesized silica materials were characterized by nitrogen adsorption/desorption experiments at 77 K to obtain BET surface area, average pore size, and pore size distributions. The morphology of the synthesized silica was checked by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM). Among all the reaction conditions, the most important ones seem to be pH and reaction time. The synthesis is not successful yet since the formation of (110) and (200) peaks is not complete based on the SBA-15 obtained from a batch reactor. However the BET surface area was sufficiently large comparing with those for conventional silica materials reported in literature. Such results are also partially confirmed by HR-TEM results.