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Humic acid-derived resin (named “RFH”) is employed for efficiently recovering gold from acidic aqueous solutions. The selectivity and effects of pH, contact time, initial concentration, and temperature on Au­(III) adsorption by RFH have been studied. The RFH resin exhibited remarkable selectivity for gold ions over other metal ions and very high adsorption capacity for Au­(III), up to 920 mg·g–1. The gold adsorption nicely conforms to the Freundlich isotherm model, and the removal of Au­(III) from the aqueous solution by RFH resin follows pseudo-second-order kinetics. The RFH resin before and after adsorption was characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which provided evidence for gold adsorption mechanism of RFH. The results showed that Au­(III) was adsorbed on RFH, then reduced to elemental gold, and deposited on the adsorbent in the form of the element gold. We summarize the process as an adsorption–reduction–deposition mechanism. This paper provide a new way for gold recovery from aqueous acidic solutions.

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Saturated vapor pressures of pure dimethyl adipate and isobaric vapor–liquid equilibrium (VLE) data for the binary system of dimethyl adipate + 1,6-hexanediol at 10, 20, and 99 kPa were determined by a modified Othmer still. All of the VLE data passed the thermodynamic consistency test by Wisniak and Van Ness methods. The experimental data were correlated with the NRTL, Wilson, and UNIQUAC models. The results showed that the UNIQUAC model is slightly better among the three models.