Rhodium Adsorption on Valonea Resol Polymer

A new adsorbent resin has been developed by immobilizing tannin acid with formaldehyde, and its adsorption properties to Rh3+ were investigated. Linear and nonlinear regression procedures have been applied to the Langmuir, Freundlich, Tempkin, Dubinin–Radushkevich, and Redlich-Peterson isotherms The resin exhibited good adsorption capacity towards Rh3+ from acidic aqueous solutions ([H+] = 1 M, [Cl-] = 10-3 M), which the equilibrium adsorption capacity was high up to 96,69 mg g−1 at 293 K. The adsorption isotherms could be well described by Langmiur equation. The experimental studies suggested that tannin formaldehyde resin was effective for the adsorption of Rh3+ from chloride acid solutions, and the loaded Rh3+ could be easily desorbed by 1 M HNO3 + 0,1 M NaClO3 solution mixture with hundred percent efficiency. Thermodynamic parameters such as the entropy change, enthalpy change and Gibb's free energy change were calculated. The adsorption of Rh3+ was an endothermic adsorption process. This suggested that the resin can be used as an active biosorbent for the recovery of Rh3+ from 1 M concentrated acidic solution.