Batch and chromatographic removal of Nd3+ and Dy3+ ions from waste solutions using humic acid

Removal of Nd3+ and Dy3+ Lanthanide metal ions from waste solutions using Giza Zoo humic acid (GZHA) was studied by batch and chromatographic column experiments. The results of batch experiments demonstrated that maximum removal of both Nd3+ and Dy3+ were 753.75 and 667.97 mg/g from 10(-2) M HCl waste solutions at pH 2.0, 323 +/- 1 K by GZHA, respectively, which are the highest values of GZHA compared with more than resent 25 adsorbents. Removal data were better described by Langmuir isotherm, while kinetics data were well fitted to pseudo second order model. Thermodynamic studies showed that the removal of both Nd3+ and Dy3+ ions using GZHA is spontaneous, favorable and endothermic reactions. The value of activation energy (Ea) for Nd3+ and Dy3+ is 11.40 and 8.19 kJ/mol, respectively suggests that the removal of both ion metals onto GZHA from waste solution under the applied experimental contion is a physicosorption process. The equilibrium removal capacity of the column ranged from 19.4 to 19.48 and 18.3 to 39.1 mg/g for Nd3+ and Dy3+, respectively. The height of mass transfer zone increased with the increase in the initial concentration of influents; h(z) is 1.8, 2.4 and 3.3 cm for Nd3+ and 1.5, 2.1 and 3.6 cm for Dy3+ at 50, 100 and 300 mg/L, respectively. The efficiency of removal column for both Dy3+ and Nd3+ is 85.4% and 77.2% at room temperature and 50 mg/L influent concentration, respectively. (C) 2016 Elsevier Ltd. All rights reserved.