title: Mercury(II) removal with modified magnetic chitosan adsorbents.
abstract: Two modified chitosan derivatives were prepared in order to compare their adsorption properties for Hg(II) removal from aqueous solutions. The one chitosan adsorbent (CS) is only cross-linked with glutaraldehyde, while the other (CSm), which is magnetic, is cross-linked with glutaraldehyde and functionalized with magnetic nanoparticles (Fe₃O₄). Many possible interactions between materials and Hg(II) were observed after adsorption and explained via characterization with various techniques (SEM/EDAX, FTIR, XRD, DTG, DTA, VSM, swelling tests). The adsorption evaluation was done studying various parameters as the effect of pH (optimum value 5 for adsorption and 2 for desorption), contact time (fitting to pseudo-first, -second order and Elovich equations), temperature (isotherms at 25, 45, 65 °C), in line with a brief thermodynamic analysis (ΔG⁰ < 0, ΔH⁰ > 0, ΔS⁰ > 0). The maximum adsorption capacity (fitting with Langmuir and Freundlich model) of CS and CSm at 25 °C was 145 and 152 mg/g, respectively. The reuse ability of the adsorbents prepared was confirmed with sequential cycles of adsorption-desorption.
authors.affiliation: Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki GR-541 24, Greece. georgekyzas@gmail.com
authors.forename: George Z
authors.initials: GZ
authors.lastname: Kyzas
authors.forename: Eleni A
authors.initials: EA
authors.lastname: Deliyanni
mesh_terms: D000327:Adsorption; D048271:Chitosan / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008628:Mercury / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D013818:Thermogravimetry; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D058185:Magnetite Nanoparticles; D048271:Chitosan; D008628:Mercury