Activated carbon productions using different biomass wastes and its toxic gas adsorption application (TMA and H2S)

Abstract

Indoor air pollution such as trimethylamine (TMA) and H2S has become a growing concern due to its more durable and directly harmful to people`s health. In this work, a porous carbon filter was developed by impregnating copper on activated carbon from different biomass wastes such as rice husk, cocoa shell, coffee residue and peanut shell. The different carbonization temperature can highly affect the texture properties of activated carbon, and the optimal carbonization temperature was found to be 450 ℃. The best activated carbon samples [SBET=2652 m2/g, VTotal=0.878 cm3/g for activated rice husk (ARH), SBET=1422 m2/g, VTotal= 0.655 cm3/g for activated coffee residue (ACR), SBET=1523 m2/g, VTotal= 0.736 cm3/g for peanut shell activated carbon (PAC)] were obtained at a carbonization temperature of 450 ℃ and a KOH activation at 750 ℃. These samples were better than the commercially available cocoa activated carbon (AC) (SBET=1042 m2/g, VTotal= 0.542 cm3/g). For H2S adsorption, a better adsorption performance was obtained in an enclosed chamber with a copper impregnation on the best activated carbon samples. The adsorption capacities were found to be 410 mgH2S/g for Cu/ARH-450, 132 mgH2S/g for Cu/ACR-450, 98 mgH2S/g for Cu/PAC-450, and 220 mgH2S/g for Cu/AC. When it comes to TMA adsorption, activated carbon from rice husk and cocoa shell showed a good adsorption efficiency (345 mgTMA/g for Cu/ARH-450, and 655 mgTMA/g for Cu/AC) , whereas only biochar from coffee residue (CCR: carbonized coffee residue) had excellent adsorption efficiency ( 396 mgTMA/g for Cu/CCR-450). This indicated that H2S adsorption mainly depend on the surface area and porosity, while TMA adsorption depend not only on surface area and porosity, but also on reactive functional groups. Adsorption isotherm and kinetic models were used to understand and optimize the adsorption process and mechanism. Langmuir isotherm model was the best fit in describing the adsorption of TMA and H2S on the carbon filter from different biomass wastes. The pseudo-first order kinetic model provided the best fit to the adsorption of H2S, whereas the pseudo-second order kinetic model provided the best fit to the adsorption of TMA. The adsorption mechanism was controlled by an intraparticle diffusion combined with film diffusion model. The spent filter for TMA and H2S removal was regenerated, and the regeneration performance of the H2S adsorption filter was better than that of the TMA adsorption filter. Furthermore, Techno-economic analysis and life-cycle analysis for cocoa activated carbon study showed this type of carbon filter with low production cost and less greenhouse gas emission. This study suggested that three biomass wastes of rice husk, coffee residue, and peanut shell are good precursors to activated carbon, and are very suitable for application in toxic gas removal. Therefore, current study was expected to expand the utilization of biomass waste for the indoor air purification. In addition, due to its simple design and manufacturing process, simple operation, low cost and high adsorption capacity, the porous carbon filter is very suitable for some household appliances such as air conditioners, refrigerators and microwave ovens for indoor air purification.

트리메틸아민 (TMA) 및 H2S와 같은 실내 대기 오염은 내구성과 사람들의 건강에 직접적인 해로움으로 인해 점점 더 우려되고 있다. 이 연구에서, 쌀 껍질, 코코아 껍질, 커피 잔류 물 및 땅콩 껍질과 같은 다양한 바이오 매스 폐기물로부터 활성탄 상에 구리를 함침시킴으로써 다공성 활성탄 필터가 개발되었다. 탄화 온도는 활성탄의 텍스처 특성에 크게 영향을 미칠 수 있으며, 최적 탄화 온도는 450 ℃ 인 것으로 밝혀졌다. 최고의 활성탄 샘플 (왕겨 활성탄: SBET=2652 m2/g, VTotal=0.878 cm3/g; 커피 활성탄: SBET=1422 m2/g, VTotal= 0.655 cm3/g; 땅콩 활성탄: SBET=1523 m2/g, VTotal= 0.736 cm3/g) 은 450 ℃의 탄화 온도 및 750 ℃에서 KOH 활성화에서 수득 되었다. 이들 샘플은 시장에서 구매한 코코아 활성탄 (SBET=1042 m2/g, VTotal= 0.542 cm3/g)보다 우수했다. 구리 함침을 갖는 활성탄 필터는 밀폐 된 챔버에서 우수한 대기 오염물 흡착이 얻어졌다. Cu/RHAC-450에 대한 최대 흡착 용량은 345 TMA mg/g 및 410 H2S mg/g이며; Cu/CRAC-450에 대해 396 TMA mg/g 및 132 H2S mg/g; Cu/CAC의 경우 655 TMA mg/g 및 220 H2S mg/g; 및 Cu/PAC-450의 경우 98 H2S mg/g. 흡착 등온선 및 운동 모델을 사용하여 흡착 공정 및 메커니즘을 이해하고 최적화했다. Langmuir 등온선 모델은 활성탄 필터에서 TMA 및 H2S의 흡착을 설명하는 데 가장 적합했다. The pseudo-first order 운동 모델은 H2S의 흡착에 가장 잘 맞는 반면, the pseudo-second order운동 모델은 TMA의 흡착에 가장 적합했다. 흡착 메커니즘은 필름 확산 모델과 결합 된 입자 내 확산에 의해 제어되었다. TMA 및 H2S 제거를 위한 폐 필터가 재생되었고, H2S 흡착 필터의 재생 성능이 TMA 흡착 필터의 재생 성능보다 우수했다. 마지막으로, 이 연구는 실내 공기 정화를 위한 바이오 매스 폐기물의 활용을 확대 할 것으로 예상되다.