Abstract
Chitosan-zeolite Na-X composite beads with open porosity and different zeolite contents were prepared by an encapsulation method. Preparation conditions had to be optimised in order to stabilize the zeolite network during the polysaccharide gelling process. Composites and pure reference components were characterized using X-ray diffraction (XRD); scanning electron microscopy (SEM); N2 adsorption–desorption; and thermogravimetric analysis (TG). Cu(II) sorption was investigated at pH 6. The choice of drying method used for the storage of the adsorbent severely affects the textural properties of the composite and the copper sorption effectiveness. The copper sorption capacity of chitosan hydrogel is about 190 mg·g−1. More than 70% of this capacity is retained when the polysaccharide is stored as an aerogel after supercrititcal CO2 drying, but nearly 90% of the capacity is lost after evaporative drying to a xerogel. Textural data and Cu(II) sorption data indicate that the properties of the zeolite-polysaccharide composites are not just the sum of the properties of the individual components. Whereas a chitosan coating impairs the accessibility of the microporosity of the zeolite; the presence of the zeolite improves the stability of the dispersion of chitosan upon supercritical drying and increases the affinity of the composites for Cu(II) cations. Chitosan-zeolite aerogels present Cu(II) sorption properties.
Highlights
Chitosan, a linear copolymer of linked β-(1,4)-glucosamine molecules obtained from renewable resources, is an effective sorbent for metal species [1,2,3,4]
Conditions of zeolite-chitosan composites are critical to the phase behaviour of the inorganic component, methods implying a long permanence of the zeolite in highly acidic asTypically, witnessed encapsulation by the X-ray diffractograms of composites reported in the literature
The exchange capacity of zeolite X as sorption-boosting charge in chitosan-zeolite composites has been preserved by controlling the encapsulation conditions
Summary
A linear copolymer of linked β-(1,4)-glucosamine molecules obtained from renewable resources, is an effective sorbent for metal species [1,2,3,4]. The preparations of chitosan-zeolite composites reported in the literature essentially follow two routes: (i) in situ formation of inorganic particles within a porous polymer matrix through sol–gel method [34,50]; (ii) encapsulation by suspension of inorganic fillers in a polysaccharide solution before gelling [5,62,63]. This last method was followed in the present work. Several procedures of drying have been compared, viz., CO2 supercritical drying and direct solvent evaporation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
