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Optimization of preparation of monolithic carbon foam from rice husk char for benzene leakage emergency

Peng, Xiao, Guo, Fengnan, Zhang, Xuan, Shi, Ning, Wu, Yan
Environmental science and pollution research international 2018 v.25 no.26 pp. 26046-26058
BTEX (benzene, toluene, ethylbenzene, xylene), X-ray diffraction, absorbents, activated carbon, adsorbents, adsorption, benzene, burning, carbonization, corn starch, desorption, experimental design, foams, kinetics, nitrogen, polyurethanes, raw materials, rice hulls, scanning electron microscopy, silica, surface area, zinc oxide
In the aim of BTEX leakage emergency, monolithic carbon foam (MCF) was designed and prepared via a simple method. Rice husk char (RHC) was chosen as raw material, polyurethane sponge (PUS) was used as sacrificed template to form inner channel, and corn starch and ZnO were employed as binder and reinforcing filler, respectively. The optimized preparation parameter was determined by adopting of Taguchi experimental design method. Both MCF-RHC and MCF-CAC were made from RHC and commercial activated carbon (CAC) under the same condition, and three reported monolithic carbon adsorbents were selected for comparative study with MCFs. The surface and structural properties were characterized by XRD, SEM, and N₂ adsorption/desorption isotherm analyses. XRD analysis results reveal that MCF-RHC was the composites of carbon, SiO₂, and ZnO, and MCF-RHC and MCF-CAC have good potential in organic adsorption. Hierarchical structure of MCF was constructed by inner macro-channel from burning up of PUS and micro- and meso-pores from resultant carbon composite, and these inner macro-channels play a more important role in benzene rapid adsorption. Specific surface area of MCF-RHC was 465.5 m² g⁻¹, which included micro- and meso-pores, which mainly come from RHC during the carbonization process. Adsorption kinetics study demonstrated that the benzene equilibrium uptake of MCF-RHC and MCF-CAC was similar, and both of data well fitted the pseudo-second-order kinetic model. However, MCF-RHC has the ability to absorb benzene more quickly, which meets the demand of absorbent utilizing in benzene leakage emergency.