Pore structure and metal adsorption ability of chitosans prepared from fishery wastes

The degree of deacetylation, molar mass, and the yield of chitosans prepare d from four fishery wastes (shrimp shell, lobster shell, crab shell, and cu ttlebone) under the same conditions were compared. The adsorption capacitie s and rates of Cu(II), Ni(II), and Cd(II) from water on chitosans were meas ured at 30 degrees C. It was shown that the equilibrium isotherms of Cu(II) could be fitted by the Langmuir equation and those of Ni(II) and Cd(II) by the Freundlich equation. The rates of adsorption, analyzed by a plot of am ount of adsorption vs, the square root of time, indicated different control ling mechanisms. The differences in metal adsorption among the four types o f chitosans could be generally interpreted by their different pore structur es such as pore size distribution and pore diameter.