Physical and Chemical Characterization of Chinese Fallen Poplar Leaf Ash: Effects of the Calcining Temperature and Aqueous Solution

Abstract

This study focused on the physical and chemical characterization of Chinese poplar leaf ash (PLA) with 500, 700 and 850 °C calcination temperatures and residual PLA leaching from aqueous solution. The grain size distribution, chemical composition and microstructure of PLA were investigated by the laser granulometric distribution, X-ray fluorescence (XRF) and scanning electron microscopy (SEM). The ash samples obtained before and after aqueous dissolution were analyzed using X-ray powder diffraction (XRD) to identify the mineral components. X-ray photoelectron spectroscopy (XPS) was used to illustrate the Si 2p and Al 2p transformation behaviors in the PLA samples. The zeta potentials, conductivities and pH values of hybrid-solutions were tested at different dissolution times. Silica, sulfur, calcium and potassium were the dominant components observed in the PLA. The conductivities and pH values were nearly stable with an increasing dissolution time. The zeta potential of PLA was calculated to be a negative value. Calcite and potassium sulfate were found in the PLA-500 and PLA-700 samples, whereas magnesite and lime were easily identified in PLA-850. The Si 2p peak shifted a lower position because of the additional synthesis of Si-OH with the increasing calcination temperature. These conclusions could help investigations into the possibility of using PLA in cement systems.