Porous ceramics are used in various industrial applications based on their physical properties, including isolation, storage, and thermal barrier properties. However, traditional manufacturing environments require additional steps to control artificial pores and limit deformities, because they rely on limited molding methods. To overcome this drawback, many studies have recently focused on fabricating porous structures using additive manufacturing techniques. In particular, the binder jet technology enables high porosity and various types of designs, and avoids the limitations of existing manufacturing processes. In this study, we investigated process optimization for manufacturing porous ceramic filters using the binder jet technology. In binder jet technology, the flowability of the powder used as the base material is an important factor, as well as compatibility with the binder in the process and for the final print. Flow agents and secondary binders were used to optimize the flowability and compatibility of the powders. In addition, the effects of the amount of added glass frit, and changes in sintering temperature on the microstructure, porosity and mechanical properties of the final printed product were investigated.

바이오물질을 포함하는 나노발전기는 무공해 에너지원이며 생분해성 전자폐기물이라는 점에서 친환경적인 전자소자이다. 특히 바이오 물질이 바이오폐기물로부터 추출될 수 있다면 바이오폐기물의 양도 줄어들 것이다. 본 연구에서는 포유동물의 피부에 존재하는 동물성 콜라겐을 이용하여 마찰전기 나노발전 기를 제작하였고 그 특성평가를 진행하였다. 마찰전기 나노발전기의 전기적 양극층은 회전 도포방법을 이 용하여 콜라겐 막을 형성하여 구성하였으며, 주사전자현미경으로 막이 다공성임을 확인하였다. 제작한 마 찰전기 나노발전기는 주기적인 기계적 운동에 의해 3 Hz에서 7 V부터 5 Hz에서 15 V의 개방전압과 5 Hz에서 3.8 μA의 단락전류를 보였다. 결론적으로, 콜라겐 함유 마찰전기 나노발전기는 센서와 같은 저전 력 구동 장치의 전원이 될 수 있으며 전자 폐기물 감소에도 유용할 것으로 기대된다.

Piezoelectric composite films which are enabled by inorganic piezoelectric nanomaterials-embedded polymer, have attracted enormous attention as a sustainable power source for low powered electronics, because of their ease of fabrication and flexible nature. However, the absorption of applied stress by the soft polymeric matrices is a major issue that must be solved to expand the fields of piezoelectric composite applications. Herein, a flexible and porous piezoelectric composite (piezoelectric sponge) comprised of BaTiO3 nanoparticles and polydimethylsiloxane was developed using template method to enhance the energy conversion efficiency by minimizing the stress that vanishes into the polymer matrix. In the porous structure, effective stress transfer can occur between the piezoelectric active materials in compression mode due to direct contact between the ceramic particles embedded in the pore-polymer interface. The piezoelectric sponge with 30 wt% of BaTiO3 particles generated an open-circuit voltage of ~12 V and a short-circuit current of ~150 nA. A finite element method-based simulation was conducted to theoretically back up that the piezoelectric output performance was effectively improved by introducing the sponge structure. Furthermore, to demonstrate the feasibility of pressure detecting applications using the BaTiO3 particles-embedded piezoelectric sponge, the composite was arranged in a 3 × 3 array and integrated into a single pressure sensor. The fabricated sensor array successfully detected the shape of the applied pressure. This work can provide a cost-effective, biocompatible, and structural strategy for realizing piezoelectric composite-based energy harvesters and self-powered sensors with improved energy conversion efficiency

바이오산업의 발전으로 의약품, 식품 등의 생산 과정의 분리/정제 공정에 사용되어 왔던 기존의 컬럼 크로마토그 래피를 대체하여 더 높은 처리효율을 갖는 막 크로마토그래피가 부상하고 있다. 본 연구에서는 서로 다른 기공 크기의 두 가 지 상용 셀룰로오스 아세테이트(Cellulose acetate, CA) 분리막을 탈아세틸화 과정을 통해, 리간드의 개질이 용이한 다공성 재 생 셀룰로오스 지지체를(Regenerated cellulose, RC) 제조하였다. 음이온 교환능을 부여하고자 grafting을 수행하였으며, 구체 적으로는 UV 중합법을 통해 4차 암모늄을 포함하는 음이온 교환 리간드(MAPTAC)를 부착하여 음이온 교환용 흡착막을 제 조하였다. 단백질 흡착 용량은 정적 흡착 용량(Static binding capacity, SBC)시험을 통해 총 단백질 흡착 용량을 측정했고, 동 적 흡착 용량(Dynamic binding capacity, DBC)을 측정하여 상용막과 비교 평가하였다. 성능 평가 결과 단백질 흡착량은 넓은 표면적에 의해 리간드 밀도가 높은, 기공 크기가 작은 순서로 높게 측정되었고, 상용 CA분리막을 탈아세틸화하고 리간드를 부착시킨 분리막(RC 0.8 + MAPTAC 43.69 mg/ml, RC 3.0 + MAPTAC 36.33 mg/ml)이 상용 막 크로마토그래피 제품(28.38 mg/ml) 대비 높은 흡착 용량을 보였다.

The recycling of solid waste materials to fabricate carbon-based electrode materials is of great interest for low-cost green supercapacitors. In this study, porous carbon foam (PCF) was prepared from waste floral foam (WFF) as an electrode material for supercapacitors. WFF was directly carbonized at various temperatures of 600, 800, and 1,000 oC under an inert atmosphere. The WFF-derived PCF (C-WFF) was found to have a specific surface area of 458.99 m2/g with multi-modal pore structures. The supercapacitive behavior of the prepared C-WFF was evaluated using a three-electrode system in a 6 M KOH aqueous electrolyte. As a result, the prepared C-WFF as an active material showed a high specific capacitance of 206 F/g at 1 A/g, a rate capability of 36.4 % at 20 A/g, a specific power density of 2,500 W/kg at an energy density of 2.68 Wh/kg, and a cycle stability of 99.96 % at 20 A/g after 10,000 cycles. These results indicate that the C-WFF prepared from WFF could be a promising candidate as an electrode material for high-performance green supercapacitors.

Porous ceramics have the advantages of low density, low thermal conductivity, and excellent mechanical properties. Among porous ceramic manufacturing methods, the replica template method allows the easy manufacturing of porous filters with the highest porosity and pores of the desired size, but it also has the disadvantage that the resulting filters have low mechanical strength. To overcome this shortcoming, mullite (3Al2O3·2SiO2) whiskers, which have excellent thermal stability and high mechanical strength, were introduced in porous ceramic structure. The mullite whiskers were synthesized using a composition of Al2O3, flyash and MoO3. The morphologies and crystal structures of the mullite whiskers with MoO3 contents were investigated in detail. When the porous ceramic with mullite whiskers was fabricated using 20 wt% MoO3 catalyst the most uniform microstructure was obtained, and the mullite whiskers showed the highest aspect ratio of 47.03. The porosity and compressive strength of the fabricated porous ceramic were 82.12% and 0.83 MPa, respectively.

A porous photocatalyst concrete filter was successfully produced to remove NOx, by mixing TiO2 photocatalyst with lightweight aerated concrete. Ultra Fine Bubbles were used to form continuous pores inside the porous photocatalytic concrete filter, which was mixed via a bubble generation experiment. The optimal mixing condition was determined to be with 4% of the bubble generation agent B. NO removal specimens were prepared for various photocatalytic loading conditions, and the specimen containing 3% P-25 removed NO at a concentration of 1.03 μmol in 1 h. The NO removal rate of the porous photocatalytic concrete filter prepared in this study was 10.99%. This photocatalytic filter performance was more than 9 times the amount of NO removed by a general photocatalytic filter. The porous photocatalyst concrete filter for removing NOx developed in this study can be applied to various construction sites and the air quality can be solved by reducing NOx contributing to the formation of fine particles.