Studying flocculation mechanism of chitosan with pyrene-fluorescence probe method

A peak/ratio in pyrene-fluorescence spectrum was employed to measure the polarity of micro-environment of chitosan adsorbing pyrene molecules. The authors have in the first time detected the pyrene-fluorescence spectrum of chitosan with different degrees of deacetylation (D. D.), and found the relationship between the flocculation of bentonite colloid by chitosan and the peak/ratio values of different molecular weight (M.W.) and D.D. of chitosan. We find that M.W. plays a key role in the flocculation, but D. D. has limited effect on it. From micro-environmental structure of view, it can be proved that the inter-particle bridging rather than charge neutralization dominates the flocculation with chitosan.