Adsorption characteristics of noble metals on the strongly basic anion exchanger Purolite A-400TL

Ion exchange is an alternative process for uptake of noble metals from aqueous solutions. In the present study, the sorption of Pd(II), Pt(IV), and Au(III) ions from aqueous solution was investigated by using Purolite A-400TL (strongly basic anion exchanger, gel, type I) in a batch adsorption system as a function of time (1 min-4 h). Initial Pd(II) concentration (100-1000 mg/L), beads size (0.425-0.85 mm), rate of phases mixing (0-180 rpm), and temperatures (ambient, 313 K) were taken into account during the Pd(II) sorption process. Moreover, the column flow adsorption study was carried out, and the breakthrough curves were obtained for Pd(II) ions. The equilibrium, kinetic, desorption, and ion-exchange resin reuse studies were carried out. The experimental results showed that Purolite A-400TL-the strongly basic anion-exchange resin could be used effectively for the removal of noble metal ions from the aqueous medium. The kinetics of sorption process is fast and the resin could be reused without reduction of capacity (three cycles of sorption-desorption, the reduction of capacity is smaller than 1 %). The column studies indicated that in the dilute acidic solution (0.1 M HCl) the working anion exchange capacity is high (0.0685 mg/cm(3)) in comparison with the other SBA resins examined under the same experimental conditions, e.g., Amberlite IRA-458 (0.0510 mg/cm(3)), Amberlyst A-29 (0.0490 mg/cm(3)), Dowex MSA-1 (0.0616 mg/cm(3)), Dowex MSA-2 (0.0563 mg/cm(3)), Varion ADM (0.0480 mg/cm(3)), and Varion ATM (0.0490 mg/cm(3)) etc. The highest % of Pd(II) desorption was obtained using thiourea, acidic thiourea, sodium hydroxide, and ammonium hydroxide as eluting agents (%D1 was in the range of 23.9-46.9 mg/g).