Chitosan nanoparticles from three-spot swimming crab shells for cupric ion adsorption from synthetic wastewater

Chitosan (CT) and chitosan nanoparticles (CTNP), extracted from three-spot swimming crab (Portunus sanguinolentus) shells by deacetylation and then ionic gelation, were used to removed pollutants from wastewater. Chitin deacetylation yield to form chitosan was 75%, measured from FT-IR spectral peak area. After forming CTNP, the FT-IR spectra showed overlapped peaks for COO− of gum arabic, used for gelation, and NH3 + at 1,417 cm-1 and the amino group at 1,554 cm-1 of chitosan. Adsorption and kinetics for Cu2+ removal by both CT and CTNP were compared. CTNP adsorption matched a Langmuir isotherm. Cu2+ adsorption by CTNP followed a second-order reaction, indicating bonding of Cu2+ to the nanoparticles. CTNP was much more effective and faster in adsorbing Cu2+ than CT by 52%, after only a 5-minute reaction time. When using CTNP, the optimum loading was 0.5 g/100 L, at pH 5, 300 rpm and 30 min.