Yuan JH Xu RK Zhang H. The forms of alkalis in the biochar produced from crop residues at different temperatures. Bioresource Technology 2011 102(3): 3488-3497. （IF 4.365 工程技术，一区）
Abstract
The forms of alkalis of the biochars produced from the straws of canola corn soybean and peanut at different temperatures (300 500 and 700 degrees C) were studied by means of oxygen-limited pyrolysis. The alkalinity and pH of the biochars increased with increased pyrolysis temperature. The X-ray diffraction spectra and the content of carbonates of the biochars suggested that carbonates were the major alkaline components in the biochars generated at the high temperature; they were also responsible for the strong buffer plateau-regions on the acid-base titration curves at 500 and 700 degrees C. The data of FTIR-PAS and zeta potentials indicated that the functional groups such as -COO(-) (-COOH) and -O(-) (-OH) contained by the biochars contributed greatly to the alkalinity of the biochar samples tested especially for those generated at the lower temperature. These functional groups were also responsible for the negative charges of the biochars.
