The role of chitosan as nanofiller of graphite oxide for the removal of toxic mercury ions

The present study focuses on the role of chitosan (CS) as nanofiller of graphite oxide (GO) in order to prepare composite materials with improved Hg(II) adsorption properties. The removal of Hg(II) from aqueous solutions was studied using adsorbents as graphite oxide (GO), graphite oxide nanofilled with chitosan (GO/CS) and magnetic chitosan (GO/mCS). Many possible interactions between materials and Hg(II) were observed after adsorption and explained via characterization with various techniques (SEM/EDAX, FTIR, XRD, DTG). The adsorption evaluation was done studying various parameters as the effect of pH (both in adsorption and desorption), contact time (pseudo-second order fitting), temperature (isotherms at 25, 45, 65 °C), in line with a brief thermodynamic analysis (ΔG0, ΔH0, ΔS0). The maximum adsorption capacity (fitting with Langmuir model) of GO at 25 °C was Qmax = 187 mg/g, while after the CS nanofilling (formation of the composite GO/CS), Qmax was increased to 381 mg/g with a further enhancement for GO/mCS (Qmax = 397 mg/g).