Comparative investigation on Ni(II) removal from electroplating wastewater by mineral adsorbent (CSAM) and ion-exchange resins
The efficiency of Ni(II) removal from electroplating wastewater is highly correlated with different adsorption materials. A Ca-Si activated mineral adsorbent (CSAM) and two ion-exchange resins (732 and D152) were compared. The adsorption of Ni (II) by three materials is spontaneous and endothermic, and their adsorption capacities are similar (48.66–65.36 mg/g at 318K), but the dosage of CSAM is less (1.0 g/L for 50 mg/L Ni(II)), its adsorption is faster (<5 min) and pH range is wider (2–7). 10% NaCl, 1 mol/L HCl and 10% NaCl +1 mol/L HCl were used as desorbent agents, and CSAM exhibited an extremely low desorption rate (1.49–3.41%). The smaller separation factor (close to 0) and XPS analysis showed that the Ni(II) adsorption on CSAM was an irreversible chemical process, which was different from the three-stage adsorption of resins. The treatment of two kinds of electroplating wastewater with high and low concentration showed that CSAM not only had a higher Ni(II) removal rates (>98.4%), but also could efficiently remove Cu(II) (>98%), total-chromium (>79%) and COD (>66%). The treatment of Ni(II) containing electroplating wastewater with ion-exchange resins is greatly affected by the complexing agent. CSAM is more suitable for the treatment of electroplating wastewater containing various metals and organic matters.
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