Adsorption study of an organo-arsenical with chitosan-based sorbents

• Chitosan-based copolymers display favorable sorption toward roxarsone.
• Copolymers display sorptive properties dependent on glutaraldehyde content.
• Selective adsorption occurs for copolymers between phosphate and roxarsone.
• Sorption properties vary with the copolymer/adsorbate system and solution conditions.

In this study, chitosan-based copolymers were prepared at various weight ratios of chitosan (C) to glutaraldehyde (G): 1:1 (CG11), 2:1 (CG21), and 3:1 (CG31). The sorption properties of these copolymers were investigated with roxarsone in simulated aquatic conditions at pH 7 in phosphate buffer, similar to that found in poultry litter leachate. The relative sorption capacity (Qm; mmol/g) of the sorbents are listed in parentheses in descending order: CG11 (1.80) > CG31 (0.945) > CG21 (0.802) > chitosan (0.416). The sorptive properties of the copolymers are comparable to granular activated carbon (GAC), a standard carbonaceous sorbent material, where Qm = 2.36 mmol/g. The adsorption properties of phenolic adsorbates such as o-nitrophenol, p-nitrophenol, and roxarsone with the CG copolymers and GAC were investigated at various pH and compared with phosphate and carbonate buffer systems.

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