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In the present study, fly ashes were obtained as a byproduct respectively from the processing of corncob in a gasification plant and from the combustion of corncob in a muffle furnace. The aim of this study is to characterize the basic properties of the fly ashes from gasification process and combustion process whilst comparing the results between these two types of solid residues to evaluate their potential applications. The results indicate that the CCA from gasification is more suitable to be used as a raw material for activated carbon owing to its larger specific surface area and higher carbon content compared with the CCA from combustion. With higher concentrations of K, Ca, and P, the CCA from gasification process is more bioavailable than CCA from combustion to be soil amendment. SEM images show that these CCA particles are agglomerated and irregular in shapes. The external surface of agglomerated particles is covered with potassium chloride. The influence of ashing temperature on ash morphology and agglomeration behavior is obvious, and the agglomeration tendency and melting degree are enhanced at high temperatures. Thermal analysis reveals the stepwise mechanism of decomposition for CCA. Specifically, the combustion CCA is more suitable for use as a pozzolan in blended cement concrete compared with the gasification CCA. Also, all ash samples with high silica content are suitable for ceramics. [ABSTRACT FROM AUTHOR]

As a by-product generated from the processing of corn, the production in China of corncob (CC) is abundant, with up to 3.87 million tons per year. The biomass gasification industries make use of the CC residue as feedstock, but large volumes of generated corncob ash (CCA) requires daily disposal. In this study, CCA was characterized by laser particle size analyzer (LPSA), X-ray fluorescence (XRF), X-ray diffraction (XRD), thermal gravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy, and energy dispersive X-ray (SEM-EDX). XRF results showed that the CCA was rich in K, Ca, and P, indicating its potential as a soil amendment. High content of SiO2 in CCA revealed its potential as a pozzolan in blended cement concrete. XRD showed the presence of crystal phases such as potassium carbonate, sylvite, arcanite, quartz, calcite, and nitrite. SEM images revealed the high agglomeration of CCA. EDX gave evidence of the external surface of agglomerated particles coated with KCl. TG-DTA analysis indicates that decomposition of CCA has stepwise mechanism. The CCA powders through a 0.154 mm sieve showed a high specific surface area of 162.32 m²/g, average pore size of 12.17 Å with pore volume of 0.116 cm³/g. The carbon residue separated from CCA has the potential to be used as activated carbon. [ABSTRACT FROM AUTHOR]