Chemically modified activated carbon with tris(hydroxymethyl)aminomethane for selective adsorption and determination of gold in water samples

In the current study, a sensitive and simple method for selective separation of gold, Au(III), from water samples prior to its determination by inductively coupled plasma-optical emission spectrometry (ICP-OES), was investigated. The method utilized activated carbon modified with tris(hydroxymethyl)aminomethane (AC-TRIS) as a solid-phase extractant. Surface properties of the AC-TRIS phase were characterized by Fourier transform infrared (FT-IR) spectroscopy. The separation parameters for effective adsorption of Au(III), including effects of pH, Au(III) concentration, shaking time, and common coexisting ions were examined using batch method. The optimum pH value for the separation of Au(III) on the new sorbent was 1.0, and the maximum static adsorption capacity of Au(III) onto the AC-TRIS was 33.57 mg g−1 at this pH and after 1 h contact time. The Au(III) adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. Results demonstrated that the adsorption of Au(III) onto activated carbon followed second-order kinetic model. In addition, the efficiency of this methodology was confirmed by applying it to real environmental samples.