Preparation and characterization of chars and activated carbons from wood wastes
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Carbon Letters https://doi.org/10.1007/s42823-020-00205-2
ORIGINAL ARTICLE
Preparation and characterization of chars and activated carbons from wood wastes Qiangu Yan1 · Jinghao Li2 · Zhiyong Cai2 Received: 22 August 2020 / Revised: 15 October 2020 / Accepted: 5 November 2020 © Korean Carbon Society 2020
Abstract Preparation of activated carbons from wood waste including northern hardwood pins-fines and wood dust was conducted and then compared through the following methods: physical pyrolysis and CO2 activation, vacuum pyrolysis and CO2 activation, CO2 gasification, and vacuum CO2 gasification processes. Experimental results show that chars and activated carbons with high surface area and pore volume are produced from wood waste through a vacuum CO2 pyrolysis/gasification process. The effects of operation variables of vacuum pyrolysis/gasification on the properties of chars and activated carbons were investigated to identify and optimize the temperature, heating time, and heating rate. The optimized vacuum C O2 gasification conditions were found to be a temperature of 800 °C, a heating rate of 20 °C/min, and a holding time of 2 h respectively. The prepared wood-chars and activated carbons were characterized by nitrogen physisorption, scanning electron microscopy (SEM). Fourier transform infrared (FTIR) spectra determined any changes in the surface functional groups produced during different preparation stages. Graphic abstract
Keywords Activated carbon · Wood wastes · Northern hardwood pins-fines · Wood dust · Vacuum pyrolysis · Vacuum gasification · CO2
1 Introduction * Zhiyong Cai [email protected] 1
Ligwood LLC, Madison, WI 53705, USA
Forest Products Laboratory, USDA Forest Service, One Gifford Pinchot Drive, Madison, WI 53726‑2398, USA
2
Activated carbon (AC) is a highly porous carbonaceous structure which is mainly composed of carbon atoms [1]. AC has a complex network of internal pore structures and a large surface area, exhibiting variable surface chemistry characteristics due to its specific production process and
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raw material source [1]. With tremendous oxygen-containing functional groups presenting on its surface which can serve as adsorption centers or active sites, AC demonstrates a high degree of reactivity to gaseous molecules and ionic adsorbates [2]. Carbon consists of 85–97% activated carbon [3], therefore, any economical material with a high carbon content can be used as a raw material resource to produce AC. In recent years, agricultural wastes have been investigated as precursors to produce ACs due to their high carbon content [4], availability and relatively low mineral content [5]. Schlesinger [6] reported that the carbon content of biomass is found to be approximately 45–50% (by dry mass). On a moisture-free and ash-free basis, most biomass contains ~ 80% volatile matter and 20% fixed carbon. Thus, biomass is generally more reactive than coal during the pyrolysis process making biomass more suitable to produce high-quality ACs. Activate
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