SBR로 광그래프트된 Silica gel의 合成 및 고무의 物性에 미치는 影響

조덕원 全南大學校 1990 국내석사

hydrated silica gel 을 저분자로 표면 처리하게 되면 silica gel 의 특성이 보강되는 예가 많이 보고되었다. 본 실험에서는 styrene-butadiene rubber 로 광그래프트된 silica gel 을 합성하고 고무의 물성에 미치는 영향을 관찰하였다. 본 실험 조건하에서 초기에 SBR 의 심한 분해 현상으로 induction period를 지난 후 조사 시간 증가에 따라 광그래프트 수율이 증가하였으며 반응물의 성분비를 변화시켜도 수율에 큰 영향을 주지 않았다. 처리된 silica gel 은 소수성인 SBR로 인한 물 흡수력 감소, 고무와 친화력 향상으로 인한 배합 분산성 향상과 표면 처리된 SBR의 가류 반응 참여로 인한 가류 결합 증가로 고무의 노화에 대한 내구력이 증가하였다. SBR로 그래프트된 silica gel은 고무의 hardness, modulus와 접착력의 향상을 보였으며 인장 강도에 대한 영향은 거의 없었다. 처리된 silica gel 의 그래프트 수율 증가에 따른 고무 물성의 증가 경향은 뚜렸하지 않았는데 이는 조사 동안 발생하는 SBR 의 산화와 분해 현상 때문으로 생각된다. SBR은 광분해로 분자량의 감소와 화학구조 조성의 변화가 일어났으며 이를 기초로 silica gel 과 SBR의 광그래프트 반응 기구를 제안하였다. Surface modification of silica gel has been reported to improve the physical properties of silica gel. Modified silica gel was synthesized by photografting styrene-butadiene rubber and its effects on the physical properties of rubber compound were evaluated. In this experimental condition, the grafted yield was increased in accordance with the increase of irradiated time after the induction period , but it was not greatly affected by the change of reactant ratio. The modified silica gel increased the durability of aged robber compound because of decreased water adsorptivity, improved dispersity and increased crosslinks on SBR surface. Hardness, modulus and adhesion properties of rubber were increased , but tensile strength was not changed by modified silica gel. The increase of photografting yield did not cause the improvement of physical properties of robber proportionally because of photooxidation and photodegradation of SBR during irradiation. Reaction mechanism for the formation of SBR photografted silica gel was proposed.

은 나노입자 혹은 은 양이온을 내포하는 메르캅토프로필 작용기화 실리카 겔과 기체 메틸아이오다이드 간의 상호작용 비교

홍정우 제주대학교 대학원 2022 국내석사

Mercaptopropyl-functionalized silica gels Including Ag+ ions or Ag nanoparticles were prepared and were used to investigate the mechanism followed for the adsorption of gaseous CH3I by each Ag. To determine the efficiency of the Ag nanoparticle embedment process utilized, Ag nanoparticles were embedded into the mercaptopropyl-functionalized silica gel through the wet chemistry method or through the electron beam irradiation method. The wet chemistry method facilitated the adsorption of the additives used for the synthesis of the silica gels with the Ag nanoparticles. In contrast, during the electron beam irradiation method, the ligand was cleaved by the electron beam and the cleavaged ligand particles underwent reassembly, followed by the interaction of the Ag nanoparticles with the silica gel. Therefore, the wet chemistry method was found to be unsuitable owing to the presence of residual additives. The embedment of the Ag nanoparticles in the silica gel samples was confirmed through transmission electron microscopy and a change in the color of the silica gels; this was followed by exposure to gaseous CH3I. Various spectroscopic analyses were used to investigate the chemical and physical changes associated with the interaction between the silica gels including different oxidation states of Ag and gaseous CH3I; X-ray photoelectron spectroscopy provided clear results. The Ag nanoparticles formed covalent bonds with the mercaptopropyl ligands, whereas the Ag+ ions formed ionic bonds. Physisorption occurred between the Ag+ ions and gaseous CH3I, followed by the decomposition of the gaseous CH3I by ultraviolet rays, resulting in the formation of AgI through an interaction between the Ag+ ions and I- . In contrast, the Ag - 5 - nanoparticles was maintained, which suggests that the Ag nanoparticles do not form AgI and gaseous CH3I remains on the surface of Ag nanoparticles. This study confirmed that the mechanism through which gaseous CH3I interacts with Ag depends on the oxidation state.

경질유 내의 질소 화합물에 대한 흡착·탈착 평형 및 속도에 관한 연구

이현정 연세대학교 대학원 2003 국내석사

Co-gel 은 Silica gel 의 개질구조로 66Å 정도의 pore 를 가지며, Light gas oil 내의 N-compounds 에 대해 비교적 큰 흡착용량을 보인다. 본 연구에서는 10, 30, 50 그리고 70℃ 온도조건에서 Co-gel 을 이용하여 N-compounds 부피비가 다른 Light gas oil 로부터의 N-compounds 을 흡착 평형 및 속도를 연구해 보았고 Solvents(MTBE, MIBK, Anisole)에 대해 탈착평형 및 속도를 여구해 보았다. 또한, Light gas oil 과 MTBE 에 대한 water effects 를 알아보기 위해 각 온도조건에서 흡착, 탈착 그리고 재흡착 평형 실험을 수행하였다. 평형 실험의 결과로서, Co-gel 에 대한 N-compounds 의 흡착은 quasichemical bond 를 형성하는 정도의 강한 흡착과 함께 physical adsorption이 일어나는 것으로 사료된다. 흡착과 탈착 평형을 동시에 고려하였을 때 50℃에서의 수행이 가장 효율적인 것으로 사료되었고 탈착 용매의 경우 Anisole 보다 MTBE 과 MIBK 의 탈착능이 더 우수함을 확인하였다. 이는 MTBE와 MIBK 보다 Anisole 이 N-compounds 에 대해 약흡착질인 것으로 사료된다. 재흡착시 탈착 평형 보다 약 300∼400 ppm/ 1g adsorbent 더 재흡착됨을 확인하였다. 속도 실험의 결과로서, 흡착 속도의 경우 10, 30℃ 온도조건에서의 physical adsorption 보다 50℃ 조건에서 quasi-chemical bond 의 형성 정도가 빠름을 확인하였고 흡착 및 탈착 속도 모두 온도가 증가할수록 흡착 diffusivity 의 값이 커짐을 확인하였다. 이는 pore 내에서의 분자 확산속도가 빨라짐으로 사료된다. Co-gel 은 순수 Silica gel 의 흡착양보다 3 배 우수함을 확인하였고 이는 Co 이 N-compounds 에 대해서 촉매역할을 하여 더 많은 흡착양을 보임으로 사료된다. Water-saturated effect 을 보면, water-saturated LGO 의 경우 강한 흡착을 보여 N-compounds 제거 효율을 감소시키고 있으며, water-saturated MTBE 의 경우 경쟁 흡착을 통해 N-compounds 탈착을 증가시키고 있음을 확인하였다. 또한 재흡착의 경우 water effect 없는 흡착평형과 비교해 보면 재흡착양이 더 많은 것을 확인할 수 있다. 따라서 Light gas oil 내에 N-compounds 의 제거율을 향상시키기 위해서는 LGO 내에 water 가 제거된 상태에서 수행하는 것이 효율적이고 탈착 시water 가 포함되어 있는 MTBE 를 사용하여 평형 실험을 수행하는 것이 더 유리함을 알 수 있었다. Co-gel are a modified form of Silica gel with pore sizes in the range of 63-67Å, designed to have relatively high adsorption capacity for N-compounds in Light gas oil. In this study, adsorption equilibrium and kinetics of N-compounds in Light gas oil which has a different N-compounds volume ratio on Co-gel and Silica gel at the temperature of 10, 30, 50 and 70℃. After adsorption equilibrium, desorption equilibrium and kinetics of N-compounds for solvents (MTBE, MIBK, Anisole). Also, to find water effects for adsorption, desorption and readsorption equilibrium, the effects of adsorption capacity and temperature condition were studied. From the result of equilibrium, N-compounds adsorption for Co-gel was considered to be a strong adsorption as making quasi-chemical bond and physical adsorption. In consideration of adsorption and desorption equilibrium, performance in case of 50℃ was considered the most efficient result. In case of desorption solvents, MTBE and MIBK was excellent desorption capacity than Anisole. This Anisole was considered weak adsorbate than MTBE and MIBK. In case of readsorption, readsorbed amounts was confirmed 300∼400 ppm /1g adsorbent than desorbed amount. From the result of adsorption/desorption kinetics, making quasi-chemical bond at 50℃ was faster than physical adsorption at 10℃와 30℃. And both adsorption and desorption kinetics were confirmed to increase in diffusivity as increasing with temperature. Co-gel is excellent than silica gel. Because Co within Co-gel is a catalytic action. For water-saturated effect, in case of water-saturated Light gas oil was decreased a rate of removal because of strong adsorption. In case of water-saturated MTBE, desorbed amounts of N-compounds was increased through competitive adsorption. Therefore, a rate of removal for N-compounds within Light gas oil was rose performance at the condition of removing water within Light gas oil. Also, performance at the condition of including water within MTBE is efficient to study desorption equilibrium

太陽熱을 利用한 食品乾燥에서 silica gel의 活用效果

전병선 忠南大學校 大學院 1983 국내석사

This experiment was carried out to elucidate the drying characteristics of onion and dehumidifying effect of air using the silicagel and to reuse it by solar collector. The results were summarized as follows. 1. It takes 14 hours to regenerate to silicagel of 8% moisture content from saturated silicagel conditions of 28℃ temperature and 55% relative humidity. 2. When sample was recycled through solar collector, the result of drying was 1/2 times more efficient than that of mat drying. 3. Average thermal efficiency of solar collector was 25% during the experimental period. 4. Browing extent was reduced to 1/2 times at heated air blow drying system using drying chamber.

실리카 인캡슐레이션 작용을 통한 농경지 토양 내 중금속의 이동성 저감 평가

박진 전북대학교 일반대학원 2023 국내석사

Heavy metals released into environments through human activities including mining, transportation, pesticide, and fertilizer can be introduced to agricultural land, and threaten seriously human health and food security by translocating to crops. Stabilization has been considered a promising process for reducing the mobility and bioavailability of heavy metals in agricultural soil. But chemical stabilizers negatively affect plant growth by changing the physicochemical properties of the soil. Silica (Si) is abundant in natural soil and can reduce the toxicity of heavy metals in plants. Therefore, in this study, silica encapsulation was proposed as a new stabilization process to prevent heavy metal translocation from soil to crops. As the amorphous silica layer was generated on the soil surface, the FT-IR peak of the soil surface was converted similarly to the peak pattern of the silica gel, and the peak intensity of the XRD decreased because of the amorphous characteristics of the silica layer. The SEM-EDS analysis shows that the intensity of heavy metals (Pb, Zn, and Cu) on the surface of the silica-encapsulated soil decreased. The results show the formation of silica layer on the soil surface. Silica encapsulation reduced the TCLP-leachable as well as the bioaccessible concentration of heavy metals, which is expected to lower the translocation of heavy metals to crops from the soil. The silica encapsulation showed the effect on the decrease of mobility even in accelerated aging (wet-dry aging). In addition, silica encapsulation promoted the germination of Lactuca Sativa and Hordeum vulgare in heavy metals-contaminated soil and reduced the concentration of heavy metals deposited in barley roots. Furthermore, silica encapsulation is effective in reducing the mobility of heavy metals regardless of the physicochemical properties of the soil and the contamination level of heavy metals. These results suggest that silica encapsulation is an effective stabilization process to prevent the translocation of heavy metals from the contaminated soil to crops while maintaining the soil environment in agricultural land. 광업, 제련업, 운송업, 농약과 비료 등 인간의 활동으로 발행한 중금속은 대기나 지하수에 의해 농경지로 유입된다. 농경지 내 중금속은 작물로 전이되어 인간의 건강과 식량 안보에 심각한 결함을 초래한다. 안정화는 농경지 토양에서 중금속의 이동성과 생물학적 가용성을 줄이는 유망한 공법으로 간주되었지만, 화학적 안정화제는 토양의 물리화학적 특성을 변화시켜 작물 생장에 부정적인 영향을 미친다는 문제가 있다. 실리카(Si)는 토양에 풍부하게 존재하고 식물에서 중금속 독성을 감소시키는 것으로 알려져 있다. 따라서 본 연구에서는 중금속이 농작물로 전이되는 것을 예방하기 위해 새로운 안정화 공법으로 실리카 인캡슐레이션(Silica Encapsulation)을 평가하였다. 토양 표면에 생성된 실리카층은 토양 표면의 FT-IR 피크 스펙트럼을 실리카겔과 유사하게 만들었고, 실리카층의 비정질 구조가 결정질 물질의 XRD 피크 세기를 감소시켰다. 또한, SEM-EDS 분석 결과, 실리카 인캡슐레이션된 토양 표면의 중금속(Pb, Zn, Cu) 비율이 감소하였으며, 이는 토양 표면이 실리카 인캡슐레이션되었다는 것을 의미한다. 실리카 인캡슐레이션은 중금속의 TCLP-용출성 및 생체 접근성을 감소시켰고, Wet-Dry aging 이후에도 중금속의 이동성을 감소시키는 효과를 유지하였다. 또한, 중금속 오염토양에서 상추와 보리로의 중금속 전이를 억제하였다. 이러한 실리카 인캡슐레이션의 효과는 중금속으로 오염된 토양에서 상추와 보리의 발아를 촉진하였다. 또한 실리카 인캡슐레이션은 토양의 물리화학적 특성과 중금속 농도에 관계없이 토양 입자를 캡슐화하였으며, 중금속의 이동성을 감소시켰다. 이러한 결과는 실리카 인캡슐레이션이 농경지의 토양 생태계를 유지하면서 중금속이 농작물로 전이되는 것을 방지하는 환경친화적인 안정화 공정임을 시사한다.

Adsorption equilibria and kinetics of CO2, CH4, CO, N2, O2, and H2 on silica gels for CO2 capture and H2 purity enhancement from steel off-gas for direct reduced iron process

정지원 Graduate School, Yonsei University 2024 국내석사

The direct reduced iron (DRI) process is highly advantageous for reducing carbon emissions in the iron and steel industries. A well-designed adsorption technology can concentrate CO2 from steel off-gases for carbon capture process and provide H2 mixtures for the DRI process. Silica gels allow for relatively easy desorption without the need for thermal or vacuum energy, because of their weak adsorption affinity and remarkable CO2 selectivity. To investigate the adsorption equilibria and kinetics of CO2, CH4, CO, N2, O2, and H2, which are major components in steel off-gases, the adsorption isotherms for each component were obtained by a volumetric method at 293–323 K and at pressures up to 1000 kPa on two silica-based adsorbents. The experimental isotherms for CO2 and CH4 were well fitted with the dual-site Langmuir model, while the single-site Langmuir model well predicted the others. The adsorption capacity followed the order of CO2>>CH4>CO>N2≈O2>>H2 in both adsorbents, and the isosteric heat of adsorption of CO2 was two to three times higher than those of the remaining adsorbates. The silica gel with higher Al content and lower surface area (S1) showed a higher adsorption capacity of CO2 under 100 kPa, whereas the higher isotherms were observed in the other (S2) at higher pressures. For the remaining adsorbates, higher isotherms were observed on S2 across the pressure ranges. The adsorption kinetics were analyzed by applying a non-isothermal adsorption model to the experimental uptake curves. The diffusional time constants and kinetic parameters showed the impact of pressure and temperature. The adsorption rate followed the order of N2>CH4≥CO>>CO2. The isotherm and uptake curve for CO2 at 308 K between silica gel pellets and particles were compared, and it indicated that macropore diffusion contributed to the overall adsorption kinetics of CO2 due to the adsorption heat resistance.

실리카겔을 狙體로 한 重金屬이온 吸着用 킬레이트樹脂에 關한 硏究

정택상 漢陽大學校 大學院 1980 국내석사

Production of soybean phosphatidylcholine by separation and purification of column chromatography filled with silica-gel

배성현 Graduate School, Korea University 2022 국내석사

High-purity phosphatidylcholine is an important phospholipid that protects the liver, improves memory, and reduces cholesterol. Recently, phosphatidylcholine has been studied for use in lipid nanoparticle (LNP) formulations, which are a means of delivery for the COVID-19 mRNA vaccine. It is also used as an emulsifier, liposome, solvent, and wetting agent for the manufacturing of cosmetics, treatment of skin diseases, and slowing of skin aging. However, many of the approaches to the separation and purification of soy-derived phospholipids employ toxic solvents such as chloroform, methanol, hexane, and isopropyl alcohol, which restricts their use for certain applications, such as those related to food, medicine, and cosmetics. Therefore, there has been significant interest in the development of high-rate, low-cost separation technologies using fermented ethanol as a solvent, which is not harmful to the human body and can be recovered in a factory. This study thus sought to increase the purity of phosphatidylcholine from a crude liquid lecithin raw material derived from soybean using low-pressure column chromatography and silica gel. The phospholipid separation pattern was first determined based on the solution eluted from the column chromatography process. Based on this, changes in the yield, phosphatidylcholine purity, lysophosphatidylcholine purity, and phosphatidylcholine recovery rate were analyzed according to the pooled fraction. Phospholipid separation patterns were then assessed according to the ethanol purity (93%, 95%, 97%, or 99%). Based on this, optimal column chromatography conditions according to the mobile phase were studied, and the production of phosphatidylcholine with a purity of 95% was investigated. An economical process was developed that increased the purity of phosphatidylcholine by removing phosphatidylethanolamine and lysophosphatidylcholine through a purification reaction using alumina and a cation exchange resin after pooling the fraction from which as many natural lipids as possible had been removed. Using this process, phosphatidylcholine with a purity of 80% and 95% was obtained, and its quality was tested by applying it to cosmetic cream formulations.

Silica gel을 使用한 充塡流動層吸濕에 關한 硏究

이철수 서울大學校 大學院 1968 국내석사

Aspartic protease analogues built on silica gel : 실리카 젤 지지체를 이용한 아스파르틸 단백질 가수분해효소 유사체에 관한 연구

정연숙 서울대학교 대학원 2003 국내박사