Bioadsorption of silver ions by chitosan extracted from the <em>Penaeus vannamei</em> (shrimp)exoskeleton

Abstract

Introduction: As the use of silver in biomedical and industrial nanotechnology increases, the possibility of finding these metal ions in wastewater increases, which pollute the biotic environment, generate organic dysfunctions in molluscs, death of birds and diseases in the population.

Objective: To evaluate the kinetics of bioadsorption of silver ions in simulated water of industrial effluents by chitosan extracted from the Penaeus sp. (shrimp) exoskeleton to contribute to solving environmental and public health problems in Peru.

Methods: An experimental and prospective study was conducted. Silver ions (Ag+) of an aqueous solution were quantified using the flame atomic absorption spectrometry method, at a wavelength of 328.1 nm.

Results: 99.1 % and 97.92 % of bioadsorption were observed at pH 4 and pH 8, respectively; it was lower in more acidic media (pH ≤ 2). The pseudo-second order kinetic model was optimal with a value of R2 =1 in the three sizes of chitosan particles; bioadsorption rate (h) of chitosan at a size of 0.25-0.18 mm was 38.911 mg·g-1·min-1 and its K2 0.063 g·g-1·min-1. At equilibrium the bioadsorption remains constant at 10, 20 and30 °C, and its K2 in that range was 0.026 to 0.043 g·g-1·min-1.

Conclusions: The bioadsorption kinetics of chitosan is pseudo-second order, with a high retention capacity of silver ions (Ag+) at pH of 4-8, at30 °C and with a particle size of 0.15-0.25 mm.