Adsorption of methylene blue by different types of straw biochar with performance comparison

Abstract

In order to study the adsorption property of straw biochar of methylene blue dye, five kinds of biochar (rice straw, corn straw, wheat straw, peanut straw and reed straw) were prepared at 500°C through the method of oxygen limiting and temperature control. The microstructure, functional group and elemental composition of biochar were characterized with a scanning electron microscope, Fourier transform infrared spectroscopy and X-ray diffraction. The adsorption experiments of the methylene blue solution by five kinds of straw biochar were carried out, and the properties of the biochars after the adsorption of the methylene blue solution were compared and analyzed. The result revealed that S500, X500 and L500 have round hole microporous structure, and Y500 and H500 have parallel wall microporous structure. The FTIR spectra of five kinds of straw biochar contained polar groups and aromatic structures. Their adsorptive capacities were as follows: X500 > S500 > L500 > Y500 > H500. Among the five kinds of straw biological charcoals, X500 had good surface characteristics and the ability to adsorb methylene blue. It is the preferred material for adsorbing organic contaminants. Moreover, the surface characteristics of the five kinds of straw biological charcoal also affected their ability to adsorb the methylene blue solution.