The sorption of two organic dyes, methylene blue and sunset yellow by biochar with two different pyrolytic temperatures (500℃ and 700℃) was studied. The effective factors such as reaction temperature, pH and sulfate concentration were also discussed. The kinetic data fitted well by pseudo second-order model and the equilibrium sorption data were best described by the Freundlish model for both the two dyes. However the sorption mechanisms of biochar for methylene blue and sunset yellow were different. The cationic methylene blue was mainly sorbed onto the biochar surface by cationic exchange, and the sunset yellow was mainly sorbed to the biochar by the π-π interaction between its aromatic ring and the aromatic structure in biochar. As the increase of pyrolytic temperature, more aromatic structure formed in biochar accompanied by loss of H- and O-containing groups, so that the ionic electrostatic attraction from methylene blue and biochar was decreased while the π-π interaction from sunset yellow and biochar was increased. The removal efficiency of the two organic dyes by biochar can be enhanced by increasing the reaction temperature from 5℃ to 45℃. The variation of pH from 3 to 7 and concentration of sulfate from 25 mg·L-1 to 2500 mg·L-1 did not show obvious effect to the removal of the two organic dyes by biochar from aqueous solution. Key words: biochar; sorption; sunset yellow; methylene blue; factors

Sorption of organic dyes by straw biochar and its effective factor

249th National Meeting (2015)

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