Title
Novel silica/polyelectrolyte multilayer core-shell composite microparticles with selectivity for anionic dyes
Authors
CLAUDIU-AUGUSTIN GHIORGHITA FLORIN BUCATARIU and ECATERINA STELA DRAGAN

Received Dedicated to the 70^th anniversary of Acad. Bogdan C. Simionescu
Published Volume 52 Issue 7-8 July-August
Keywords polyelectrolyte multilayer films, chitosan, carboxymethyl cellulose, dye sorption

Abstract
In this paper, novel core-shell composites were fabricated by the deposition of polyelectrolyte multilayer films based on chitosan and poly(N,N-dimethylamino)ethyl methacrylate partially quaternized with benzyl chloride, as polycations, and carboxymethyl cellulose as polyanion onto silica microparticles. After construction, the films were cross-linked with a dihalogenated aromatic derivative. The role of polyelectrolyte deposition solutions in charge balance and morphology of the composites was investigated by potentiometric titrations and scanning electron microscopy, respectively. The new composites were tested as sorbents for four organic dyes (methylene blue, methyl orange, bromocresol green and Congo red), showing better sorption capacity for the anionic compounds. An insight into the sorption mechanisms of anionic dyes was obtained by fitting the equilibrium sorption isotherms with the Langmuir and Freundlich models, and the sorption kinetics with the pseudo-first order and pseudo-second order models. The optimum pH conditions for desorption of the dyes were also assessed. These results provide important information on the design of multilayer films containing diverse building-blocks on colloidal cores capable to selectively load ionic species.