Wooden Activated Carbon Production for Dioxin Removal via a Two-Step Process of Carbonization Coupled with Steam Activation from Biomass Wastes

Abstract

A two-step process of carbonization coupled with steam activation was proposed for wooden activated carbon production from four kinds of biomass waste materials. The TG-FTIR results show that the carbonization process started at around 250 °C and finished at 500 °C for the coconut shell, pinewood, and plywood. The carbonization temperature of corn straw was lower than those of the other three samples, which was attributed to the higher concentration of ash content. FTIR results for the volatile compounds during carbonization show that CH 4 , CO, CO 2 , and hydrocarbons are the main detected gaseous species. The CH 4 and C m H n yields of pinewood and plywood are higher than those of the coconut shell and corn straw. The carbonization results on the tubular furnace reactor show that furfural and phenol and its derivatives are the main tar compounds in waste carbonization. Carbonization experiments show that a temperature of 500 °C and residence time of 30 min are the optimized parameters for the three biomass wastes. The char yields are 26.4, 25.73, and 30.38% for pinewood, plywood, and coconut shell, respectively. CFD modeling has proven that using 20% of the volatiles could achieve lowest pollution and provide heat for carbonization of biomass waste. The steam activation results show that an activation temperature of 800 °C and activation time of 30 min are suitable for all three biomass samples, which could obtain optimized AC yields and adsorption quality for dioxin.

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“…It indicated that too much steam would lead to over activation and the decline of BET specific surface area. We et al 36 also reported similar results for steam activation of pinewood. The steam activation of char is a typical gasification process.…”

“…The steam activation of char is a typical gasification process. The global reactions during char‐steam interaction could be summarized as follows 36,37 : …”

Experimental Study on the Preparation of Lignin-Based Activated Carbon and the Adsorption Performance for Phenol

“…Therefore, 500 °C could be chosen as the carbonization temperature for coconut shell during the two-step activation carbon production. Wei et al 36 also reached a similar conclusion.…”

“…Next, steam activation of coconut shell char was conducted. Steam is a kind of typical activation agent during physical activation . The heterogeneous reaction between char and steam (gasification reaction) was controlled by reaction temperature, residence time, and the amount of steam .…”

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“…11,33–35 Steam, CO 2 , and air (in fact O 2 plays the role) are often used as activation agents in physical activation. 15,36–45 Pores are generated by the oxidation–reduction reactions between the activation agents and carbon matrix during the physical activation process (eqn (1)–(3)). 46 C + H 2 O → CO + H 2 C + CO 2 → COC + O 2 → CO 2 …”