이산화탄소 환경 내 공동 열분해를 통한 나노 철 산화물 기반 금속 바이오차 제조 및 Cr(VI) 흡착 연구 = A Study on Preparation of Nano Iron Oxides-Based Metal Biochar Using Co-Pyrolysis in a CO2 Environment and Adsorption of Cr(VI)

다국어 초록 (Multilingual Abstract)

This study explored the effects of blending nano iron (III) oxides (NIO) with coffee grounds (CG) in a pyrolytic process under a CO2 environment on the generation of syngas (H2 and CO) and biochar properties regarding the removal of Cr(VI) from aqueous solutions. CG and NIO were physically mixed; CG was mass maintained at 1 g while NIO was added. Based on the mass ratio, the resulting solution was named NICG1(NIO/CG ratio=1:1). Compared with the generation amounts of syngas (0.37 mole% H2 & 0.28 mole% CO) at 650°C from single pyrolysis of CG, co-pyrolysis with NIO-based additives resulted in increased production of syngas, with the measured concentrations of H2 and CO reaching 0.99 mole% and 0.86 mole% at the same temperature, respectively. During the pH effect experiments, NICG1 demonstrated the highest removal efficiency under acidic conditions with pH = 2. Adsorption kinetic experiments demonstrated that the pseudo-second-order rate model was suitable for assessing the removal of Cr(VI) by NICG1. Furthermore, the removal of Cr(VI) using NICG1 fitted well with the Freundlich isothernm adsorption model (R2 = 0.9807). In conclusion, co-pyrolysis of blending nano iron(III) oxide and coffee grounds can be considered an efficient resource for simultaneously producing syngas (H2 and CO) as a fuel (energy resource) and metal-biochar as an adsorbent.

국문 초록 (Abstract)

본 연구는 이산화탄소 환경에서 금속 나노 철 산화물(NIO)과 커피찌꺼기(CG)의 혼합 열분해 공정에 대한 합성 가스(H2 & CO) 생성에 미치는 영향 및 제조된 금속 바이오차(NICG1)의 수용액 내 6가크롬 제거에 대해 조사하였다. 650°C에서 CG의 단독 열분해는 0.37 mole% H2와 0.28 mole% CO의합성 가스 생성을 보였고, NIO를 첨가한 공동 열분해를 통해 합성 가스의 생성량이 증가하였으며, NICG1의 동일한 온도에서 측정된 H2및 CO 농도는 0.99, 0.86 mole%였다. 흡착 실험 결과, NICG1 은 pH 2의 산성조건에서 가장 높은 제거 효율을 보였으며 유사 2차 속도 모델에 의한 6가 크롬 제거에 적합하다는 것을 보여주었다. 또한 NICG1을 사용한 6가 크롬 제거는 Freundlich Isothernm 흡착모델(R2 =0.9807)에 더 적합하였다. 결론적으로 폐자원인 커피찌꺼기와 나노 철 산화물의 co-pyrolysis를 통해 연료자원인 합성 가스(H2와 CO)와 흡착제인 금속 바이오차를 동시에 생성할 수있어 커피찌거기의 활용에 대한 높은 평가를 받을 수 있다.

참고문헌 (Reference)

1 Kwon, G., "Valorization of plastics and goethite into iron-carbon composite as persulfate activator for amaranth oxidation" 407 : 127188-, 2021

2 Lee, S., "Use of CO2 and nylon as the raw materials for flammable gas production through a catalytic thermo-chemical process" 23 : 8922-8931, 2021

3 Liu, S. S., "Understanding the catalytic upgrading of bio-oil from pine pyrolysis over CO2-activated biochar" 174 : 538-546, 2021

4 Amjed, M. A., "Surface decoration and characterization of solar driven biochar for the removal of toxic aromatic pollutant" 96 : 2310-2324, 2021

5 Molday, R.S., "Separation of Cells Labeled with Immunospecific Iron Dextran Microspheres Using High-Gradient Magnetic Chromatography" 170 : 232-238, 1984

6 Rahman, M.A., "Removal of arsenate from contaminated waters by novel zirconium and zirconium-iron modified biochar" 409 : 124488-, 2021

7 Zhang, X., "Removal of aqueous Cr(VI) by a magnetic biochar derived from Melia azedarach wood" 256 : 1-10, 2018

8 Zhang, W. H., "Pb(II) and Cr(VI) sorption by biochars pyrolyzed from the municipal wastewater sludge under different heating conditions" 147 : 545-552, 2013

9 Treybal, R.E., "Mass-transfer operations" McGraw-Hill 1980

10 Zhou, L., "Investigation of the adsorption-reduction mechanisms of hexavalent chromium by ramie biochars of different pyrolytic temperatures" 218 : 351-359, 2016

11 Jarup, L., "Hazards of heavy metal contamination" 68 : 167-182, 2003

12 Arora, S., "Gasification biochar from horticultural waste: An exemplar of the circular economy in Singapore" 781 : 146573-, 2021

13 Chandra Sekhar, K., "Fractionation studies and bioaccumulation of sediment-bound heavy metals in Kolleru lake by edible fish" 29 : 1001-1008, 2004

14 Audry, S., "Fifty-year sedimentary record of heavy metal pollution (Cd, Zn, Cu, Pb) in the Lot River reservoirs (France)" 132 : 413-426, 2004

15 이우진 ; Jeongyun Choi ; Yoojin Jung, "Fe(II)-initiated reduction of hexavalent chromium in heterogeneous iron oxide suspension" 한국화학공학회 25 (25): 764-769, 2008

16 Yoon, K., "Enhancement of syngas for H-2 production via catalytic pyrolysis of orange peel using CO2 and bauxite residue" 254 : 113803-, 2019

17 Su, M., "Enhanced hexavalent chromium removal by activated carbon modified with micro-sized goethite using a facile impregnation method" 647 : 47-56, 2019

18 Wan, S. L., "Enhanced Fluoride Removal from Water by Nanoporous Biochar-Supported Magnesium Oxide" 58 : 9988-9996, 2019

19 Xu, F., "Direct chemical looping gasification of pine sawdust using Fe2O3-rich sludge ash as an oxygen carrier: Thermal conversion characteristics, product distributions, and gasification performances" 304 : 121499-, 2021

20 Song, H., "Coupling carbon dioxide and magnetite for the enhanced thermolysis of polyvinyl chloride" 696 : 133951-, 2019

21 Li, Y., "Biosorption of Cr(VI) onto Auricularia auricula dreg biochar modified by cationic surfactant: Characteristics and mechanism" 269 : 824-832, 2018

22 Cho, S. H., "Biofuel Production as an Example of Virtuous Valorization of Swine Manure" 9 : 13761-13772, 2021

23 Park, J. H., "Biochar reduces the bioavailability and phytotoxicity of heavy metals" 348 : 439-451, 2011

24 Zhang, X., "Adsorption-reduction removal of Cr(VI) by tobacco petiole pyrolytic biochar:Batch experiment, kinetic and mechanism studies" 268 : 149-157, 2018

25 Chen, X. C., "Adsorption of copper and zinc by biochars produced from pyrolysis of hardwood and corn straw in aqueous solution" 102 : 8877-8884, 2011

26 Yoon, K., "Adsorption of As(V) and Ni(II) by Fe-Biochar composite fabricated by co-pyrolysis of orange peel and red mud" 188 : 109809-, 2020

27 Qi, W. F., "Adsorption behavior and mechanism of Cr(VI) using Sakura waste from aqueous solution" 360 : 470-476, 2016

28 Wan, S. L., "Accelerated antimony and copper removal by manganese oxide embedded in biochar with enlarged pore structure" 402 : 126021-, 2020