Silver-complexed chitosan microparticles for pesticide removal

摘要

Two types of chitosan microparticles (CMs) and their silver-complexes CMs (SCMs) were prepared using different crosslinking agents, i.e. glutaraldehyde and epichlorohydrin, in order to investigate the adsorption and release behaviors of a typical pesticide, methyl parathion (MP). The pH and concentration dependencies on Ag(I) and MP adsorptions on both the CMs and SCMs were studied. The epichlorohydrin-crosslinked CM apparently showed the superiority of Ag(I) adsorption over the glutaraldehyde-crosslinked CM, nevertheless, adsorption behavior of MP on SCM derived from each CM was observed vice versa. Release behavior of MP from the MP-loaded SCMs was also observed in aqueous acetic acid and sodium acetate buffer solutions at low pH as well as in those containing two kinds of ammonium reagents. The aqueous solutions containing ammonium thiocyanide and ammonia could be applied for MP release from the MP-loaded SCMs without Ag(I) leakage from the particles. Furthermore, from the iteration of adsorption and release experiments of MP, glutaraldehyde-crosslinked SCM provides good reusability for MP removal.