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| Effects of pyrolysis processes under CO2-N2 atmosphere on Cd2+ adsorption by rice straw biochar |
| Received:December 21, 2019 |
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| KeyWord:biochar;pyrolysis;CO2-N2 atmosphere;rice straw;cadmium |
| Author Name | Affiliation | E-mail | | ZHOU Hong-wei | Geological Environment Exploration Institute of Jiangsu Province, Nanjing 211102, China | | | CHEN Zhen-yan | Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China | | | HU Chao | Geological Environment Exploration Institute of Jiangsu Province, Nanjing 211102, China | | | ZHANG Ya-ping | Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China | amflora@seu.edu.cn | | GU Dong-qing | Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China | |
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| Abstract: |
| The physicochemical and adsorption properties of biochar depend widely on its processing conditions. To find the pyrolysis conditions suitable for converting rice straw into high efficient biochar for cadmium adsorption, the effects of pyrolysis temperature, resident time, heating rate, and reaction atmosphere on biochar's characteristics were studied. The ratio of CO2 in the mixed atmosphere and the complete set of pyrolysis condition parameters matching it were determined based on a reaction atmosphere of CO2-N2. The properties of biochar were determined by several characterizations such as pH value, Fourier-transform infrared(FTIR)spectroscopy, and BrunauerEmmett-Teller(BET)analysis as well as adsorption experiments. The results showed that the addition of CO2 into a reaction atmosphere significantly affected a well-developed porous structure and introduced oxygen-containing functional groups onto the surface. After comprehensively considering the influencing factors of Cd2+ removal efficiency, biochar yield, and cost, the most reasonable ratio of CO2 was finally determined to be 0.5. Other parameters matching the CO2-N2 atmosphere were:a pyrolysis temperature of 800℃, resident time of 1 h, and heating rate of 10℃·min-1, respectively. The biochar prepared in the optimal pyrolysis conditions had a high removal efficiency of Cd2+ of up to 96.6% from the initial 250 mg·L-1 Cd2+ concentration solution, indicating that this method could convert agricultural waste biomass into high value-added products to deal with cadmium in wastewater. |
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