Physical and Chemical Characterization of the Ash of Fallen Chinese Willow Leaves: Effects of Calcination Temperature and Aqueous Solution

Abstract

ABSTRACTThe study is focused on the physical and chemical characterization of Chinese willow leaf ash (WLA) produced by calcination at 500, 700, and 850°C and on WLA residue leaching to the aqueous solution. The grain size distribution, chemical composition, and microstructure of WLA were investigated by laser granulometric distribution, X-ray fluorescence (XRF), and scanning electron microscopy (SEM), respectively. The ash samples obtained before and after dissolution were analyzed using X-ray powder diffraction (XRD) to identify the minerals. The X-ray photoelectron spectroscopy (XPS) of WLA was used to illustrate the Si2p and Al2p transformations. The zeta potential, electrical conductivity and pH values of a WLA mixing solution were tested as a function of dissolution time. Si and K were the dominant constituents of the WLA. The electrical conductivity value was nearly stable at longer dissolution times. The zeta potential of WLA was negative. Calcite, sylvite, and synthetic corundum were detected in the WLA samples prepared at 500ºC, quartz, calcite and sylvite were easily identified in the WLA samples prepared at 700ºC, and wollastonite, lime, and anhydrite were detected in WLA prepared at 850°C. The peak of Si2p intensity line shifted to a lower position due to the higher levels of Si-O-X synthesized at elevated calcination temperature. These conclusions could help to identify a possible use of WLA in the cementing systems.