Assembled alginate/chitosan micro-shells for removal of organic pollutants

Natural polyelectrolyte micro-shells were constructed through layer-by-layer (LbL) assembling of alginate sodium (ALG) and chitosan (CHI) onto weakly cross-linked melamine formaldehyde (MF) colloidal particles and subsequent removal of core. The assembled materials presented good film formation ability. It was found that under moderate conditions (room temperature, pure water solution) the ALG/CHI micro-shells can effectively load organic pollutants such as 2,4-dichlorophenol (DCP) and salicylic acid (SA). SEM and AFM images confirmed that the loading behavior of pollutants in the shells occurred and displayed that the feature of shell architecture changes before and after loading. The loading amount of pollutants into shell system was calculated and characterized through HPLC. The loading kinetics analysis showed that the loading process can reach an equilibrium state after approximately 4 h. Compared to the conventional polyelectrolyte (PSS/PAH)5 shells, the (ALG/CHI)5 shells had stronger adsorption capacity and faster adsorption rate for pollutant loading. The adsorption isotherm result of organics in the ALG/CHI micro-shells can be well described by Langmuir equation. Advantages of the assembled natural micro-shells composed of ALG/CHI i.e. efficient loading ability to pollutants in aqueous ecosystem, good stability responded to external stimuli as well as fast loading process render them potentially applicable as environmental-friendly micro-container for the treatment of organic pollutants from aqueous solution.