초록 ▼

최종 목표
4종의 광물자원으로부터 합성된 고순도 나노소재 원료물질(철수용액, 규산나트륨, 인산칼슘, 정제흑연)로부터 폐수 고도처리제, 반사용 단열재, 복합 생체 재료, 그래핀 및 복합체 등의 산업용 원료소재 제조 기술 개발
개발내용 및 결과
· 자철석으로부터 Cr(VI) 흡착용량 95%, 탈거효율 95%이상 성능을 가진 자성 나노흡착제 제조
· 규질이암(소디움실리케이트)으로부터 반사도 90% 이상 반사형 단열재용 실리카 중공체(다공체) 제조
· 석회석으로부터 인산칼슘 나노분체, 생체용 칼슘실리케이트(CaO

최종 목표
4종의 광물자원으로부터 합성된 고순도 나노소재 원료물질(철수용액, 규산나트륨, 인산칼슘, 정제흑연)로부터 폐수 고도처리제, 반사용 단열재, 복합 생체 재료, 그래핀 및 복합체 등의 산업용 원료소재 제조 기술 개발
개발내용 및 결과
· 자철석으로부터 Cr(VI) 흡착용량 95%, 탈거효율 95%이상 성능을 가진 자성 나노흡착제 제조
· 규질이암(소디움실리케이트)으로부터 반사도 90% 이상 반사형 단열재용 실리카 중공체(다공체) 제조
· 석회석으로부터 인산칼슘 나노분체, 생체용 칼슘실리케이트(CaO·SiO₂)계 겔 제조 조건 확립 및 고분자합성을 통합 항균성 유·무기 복합재료 개발 생체적합성 평가 완료
· 흑연으로부터 고순도 흑연 나노분말, 그래핀(GR) 및 그래핀 복합체(Pd-GR, Pt-Au-GR) 제조 최적 조건 확보 및 바이오/에너지 소재 적용성 평가 완료
기대효과
· 나노소재 제품 생산에 안정적으로 원료를 제공함으로써 자원 확보 및 나노기술의 실용화에 공헌
· 나노소재 원료물질의 직접 활용 기술 개발로 첨단 산업용 나노소재 제조 기반기술 확보
적용분야
폐수고도처리제, 반사용 단열재, 복합 생체 재료, 에너지, 환경 및 의료 산업용 원료소재 제조 분야

Abstract ▼

Ⅳ. Results and Discussion
1. Synthesis of highly functional nano-adsorbents from magnetite
We have developed new technologies to produce highly functional nano-adsorbents from a low-grade magnetite ore in two stages: the first stage from 2006 to 2010 and the second stage from 2011 to 2014. The

Ⅳ. Results and Discussion
1. Synthesis of highly functional nano-adsorbents from magnetite
We have developed new technologies to produce highly functional nano-adsorbents from a low-grade magnetite ore in two stages: the first stage from 2006 to 2010 and the second stage from 2011 to 2014. The results of our research were summarized as follows: During the first stage, we focused on the purification of a low-grade magnetite ore and the synthesis of iron acetate. In 2006, magnetite ore was leached using strong acids, iron hydroxides were precipitated by neutralization of the leachate using basic solutions. And then the precipitate was dissolved in acetic acid and dried in an alkaline environment, resulting in the formation of ferrous acetate. Next year, the purity of ferrous acetate was increased up to 95%. In 2008, the process was scaled-up to a bench scale of 50 g/h. The process was further scaled-up to a semi-pilot scale of 5 kg/h in 2009. Before commercialization, we checked out potential problems that may occur in a large-scale production and optimized the whole hydrometallurgical process for a semi-pilot scale of 3 kg/batch.
In the second stage, based on the knowledge and experience obtained in the course of the first-stage research, we prepared a high-purity Fe leachate to synthesize high-purity nano-adsorbents, and improved their characteristics of heavy metal adsorption and desorption. In 2011, we designed the process to eliminate the intermediate process of precursor preparation so that it was possible to produce nanomaterials from low-grade ore more effectively. Next year, we improved the purification process by employing solvent extraction technology and synthesized highly pure magnetite nanoparticles of Fe 99 wt%. Moreover, the wastewater from the purification process was introduced to remove phosphate from sewage. In 2013, to use the magnetite nanoparticles as a water treatment agent, we produced highly stable nanofluids by modifying the particle surface with various surfactants. In addition, we produced nanoparticle agglomerates by controlling drying and dispersion processes. In the last year of the second stage, the magnetite nanoparticle agglomerates were used as an adsorbent of heavy metal anions, e.g., Cr(VI), and their properties were improved to enhance adsorption and desorption performance. Their adsorption capacity and efficiency for Cr(VI) anions were measured 22.0 mg/g and greater than 95%, respectively.
In addition, the surface oxidation of magnetite nanoparticles enhanced the desorption efficiency over 95%, allowing them to be reused without any performance degradation. As a result, we developed a technology to produce, from a low-grade iron ore, highly functional nano-adsorbents that may be employed in the economic treatment of heavy metals in industrial wastewater.
2. Synthesis of hollow silica particles from siliceous mudstone
We have investigated to develop a new and facile method to synthesis silica sources, such as TEOS and sodium silicate, from siliceous mudstone and to produce hollow silica particles from the as prepared silica sources for light reflection applications. This investigation was divided into two steps, and the first step had been carried out for 5 years (2006 to 2010) and the second step had been carried out during 4 years (2011 to 2014). The results of the investigation were listed below.
The first year in the first stage (2006), we synthesized sodium silicate from siliceous mudstone using NaOH. We produced sodium silicate and silica-organic compound using the optimized process as developed in the first year. Also, we developed the effective method to improve the purity of the silica sources in the third year. In the forth year, we produced scale up process for the synthesis of the silica sources and the last year in the first step, we developed semi-pilot process to produce the silica sources and explored possibility to synthesize the functional nano sol composite which can provide the basis to produce nano silica composites.
The first year in the second stage (2011), we produced silica nano composite using TEOS and sodium silicate precursor which were obtained by the investigation of the first stage. Also, we produced hollow silica particles using TEOS for heat insulating application in the next year. In the third year, we optimized the synthesis process for the hollow silica particles using TEOS and we also developed synthesis method for hollow silica particles from sodium silicate in the forth year.
3. Synthesis of bio-ceramic composites from limestone
We investigated on the synthesis of calcium phosphate nano-powder, calcium silicate gel, antibacterial organic-inorganic based composites from natural limestone and carried our their applications from 2006 to 2014. The working period was mainly distinguished first stage (2006-2010) and second stage (2011-2014). Important results obtained through two working stages are as follows.
In the first stage’s work, production and evaluation were carried out in a material suitable for the biological material from the limestone. High purity limestone and calcium phosphate nano-powder by the physical and chemical process in the first year of the first stage (2006). In the second year (2007), produced a large amount of the bio-ceramics through the scale up of the production of the calcium phosphate powder. In the fourth year (2009), calcium phosphate powder has developed a synthetic and honeycomb structured artificial bone was manufactured using limestone. In the fourth year (2009), was synthesized a synthetic calcium silicate gel of calcium phosphate using an ultrasonic chemical methods. In the last year (2010) of first stage, it was possible as an industrial raw material for the purification and production of fine powder of limestone. The 30CaO·70SiO₂ gel was investigated biological activity performance over in vitro test, evaluation of the material having a function as a biomaterial has been performed. Was possible to size control (average 0.26 ㎛) in industrial fine powder from limestone. Apatite formed from calcium silicate was produced in the material that appear in the beginning.
In the second stage’s work, intensive study were conducted to evaluate the synthetic biocompatible calcium silicate gel produced a composite material for enhancing the performance and function of biological material from the limestone. In the first year of the second stage’s work (2011), 30CaO·70SiO₂ gel was prepared and the organic-inorganic hybrid material through a synthesis of PEEK for the bio-polymer, it was confirmed that the expression of biological material that has superior performance characteristics that appear in 1 day. In the second year (2012), produce high purity Ca solution from limestone, sol-gel process using method was synthesized 30CaO·70SiO₂ gel. In addition, the organic-inorganic composite material produced through the synthesis 30CaO·70SiO₂ gel and PEEK, it was possible to obtain results that biological activity performance excellent. In the third year (2013), by adding Ag ions to 30CaO·70SiO₂ gel was prepared in a antibacterial material, and investigate the concentration of Ag ions suitable for osteoblast in the evaluation of bio-compatibility and toxicity. In the last year of second stage (2014), Ag ions by synthesis 30CaO·70SiO₂ gel and PEEK was added to produce an organic-inorganic composite material (Ag-30CS/70PEEK) which shows antibacterial, biological activity performance 1 day, expressed in adherent osteoblast in the evaluation of bio-compatibility and antibacterial excellent, it was confirmed by the toxicity is not material. Furthermore, bacterial infections during biological implantation and to confirm the suppression of growth, and is a composite material of the role and function of the biological material are met.
4. Synthesis of graphene from graphite
We investigated on the synthesis of high purity graphite, nanosized graphite, graphene (GR) and graphene based composites from natural graphite and carried our their applications from 2006 to 2014. The working period was mainly distinguished first stage (2006-2010) and second stage (2011-2014). Important results obtained through two working stages are as follows.
In the first stage’s work, preparation of high purity graphite and nanosized graphite from natural graphite had been focused. Natural graphite was expanded by thermal treatment and purified for improving grinding efficiency by physical and chemical process in the first year of the first stage (2006). Fine powder of the as-purified graphite was fabricated by wet-grinding process in the second year (2007). A process for simultaneous exfoliation and grinding of the as-prepared fine graphite powder was developed in the third year (2008). A grinding technology to nanosized graphite powder was developed in the fourth year (2009). In the last year (2010) of first stage, on the basis of technology developed by a lab scale experiment, a semi-pilot scaled preparation of nanosized graphite powder was successfully achieved. High purity (99.9%) graphite powder having 1-3 ㎛ in size, 20-50 nm of thickness was synthesized through the first stage’s work.
In the second stage’s work, we have focused on the synthesis of graphene and its composites and have measured performance to apply into the biosensor and enregy materials. Firstly, graphene oxide was synthesized from graphite by the liquid phase oxidation reaction and a three dimensional graphene like crumpled paper ball was fabricated using aerosol process in the first year of the second stage’s work (2011). The 3D graphene solved the stacking problem of 2D graphene sheets and exhibited superior material properties. In the second year (2012), 3D graphene based composites such as GR-Pt-TiO₂ and Gr-Pt were synthesized by one-step aerosol process. Their application to glucose biosensor and fuel cell catalyst was conducted, respectively. The results showed enhanced sensitivity in both cases. Novel metals-graphene composites such as Gr-Pt-Au and GR-Pd were synthesized by aerosol process in the third year (2013). The as-prepared composites were applied to glucose biosensor and exhibited high sensitivity as prospective biosensor. In addition, a thin film deposition of graphene on the surface of FTO substrate was conducted using a Langmuir-Blodgett method and it resulted in high efficiency as a dye sensitized solar cell.
In the last year of second stage (2014), graphene based composites such as GR-Au and GR-Pt-Ag were synthesized by aerosol process and applied to prostate specific antigen immunosensor and glucose biosensor, respectively. The composites showed highly promising sensitivity in both cases. In order to obtain basic data to design a large scaled reactor, a bench scaled aerosol reactor was designed and installed to synthesize 3D graphene and test operation was successfully carried out. Besides, the as-fabricated 3D graphene was applied to dye sensitized solar cell. It’s performance as a dye sensitized solar cell exhibited improved efficiency.