Solid phase sorption of microamount of Hg(II) onto 1-(2-thiazolylazo)-2- naphthol (TAN) loaded polyurethane foam

Mercury is a toxic environmental pollutant. A method has been developed to remove these metal ions by preconcentrating onto 1-(2-thiazolylazo)-2-naphthol (TAN) loaded polyurethane (PUR) foam that proves an excellent sorbent for these metal ions. The accumulation conditions are optimized with respect to pH, shaking time, loading capacity and adsorbent weight. The optimum pH for sorption was found to be 7, which is close to the natural water. Optimum shaking time for Hg(II) is 30 min. The kinetic studies indicate that sorption occurs through intraparticle diffusion process. Classical adsorption isotherms are applied to determine the nature of sorption. The sorption free energy value indicates that adsorption process is chemisorption. Effect of temperature has been used to compute the values of ΔH, ΔS and ΔG for Hg(II). These are 19.0±0.9 kJ mol^-1, 80.73±0.1 J K^-1 mol ^-1, -5.1±0.9 kJ mol^-1 respectively. Adsorption of metal ions is endothermic, spontaneous and entropy driven. Effect of different anions and cations are observed. Adsorption via Hg(II)-TAN complex formation on PUR foam was supported by spectrophotometric studies.