Competitive adsorption of Cd2+, Pb2+ and Ni2+ onto Fe3+-modified argillaceous limestone: Influence of pH, ionic strength and natural organic matters

• Published in: The Science of the total environment Vol. 637-638; pp. 69 - 78
• Main Authors: He, Shuran, Li, Yongtao, Weng, Liping, Wang, Jinjin, He, Jinxian, Liu, Yonglin, Zhang, Kun, Wu, Qihong, Zhang, Yulong, Zhang, Zhen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2018
• Subjects: Competitive adsorption; Fe3+-modified argillaceous limestone; Glycine; Heavy metal; Humic acid; Competitive adsorption; Glycine; Fe3+-modified argillaceous limestone; Humic acid; Heavy metal
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.04.300

In present study, the feasibility of applying a natural adsorbent with Fe3+ modification (Fe3+-modified argillaceous limestone, FAL) on the competitive adsorption of heavy metals (i.e., Cd2+, Pb2+ and Ni2+) was evaluated. The current results revealed an efficient adsorption on Cd2+, Pb2+ and Ni2+ in mono-metal system. Further experiments demonstrated a high selectivity of Pb2+ during the competitive adsorption of Cd2+, Pb2+ and Ni2+. The adsorption selectivity of the metal ions followed the order of Pb ≫ Cd > Ni. In addition, both pH and ionic strength are important factors affecting the metal adsorptions. It is interestingly that various NOMs (i.e., humic acid (HA) and glycine (Gly)) exerted different effects on the adsorption behaviors, probably due to the different affinities for Pb2+, Cd2+ and Ni2+ and the redistribution of newly-formed metal-DOM complexes. X-ray photoelectron spectroscopy (XPS) analysis together with X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analysis revealed that the metal adsorptions were mainly regulated via the synergistic mechanisms of ion exchange by Na+, Ca2+, and Al3+, precipitation to form CdCO3 and Pb2(OH)2(CO3)2, as well as complexes of FAL-OPb and FAL-ONi by hydroxyl groups on the surface of FAL. The application of FAL would be a promising option in leading to an efficient heavy metal removal. [Display omitted] •Fe3+-modified argillaceous limestone showed effective adsorption of Cd2+/Pb2+/Ni2+.•The adsorption selectivity of the metals followed the order of Pb ≫ Cd > Ni.•Both pH and ionic strength played key roles in metal adsorption.•Humic acid and glycine exerted distinct effects on adsorption behaviors of metals.•Mechanisms of metal adsorption were ion exchange, precipitation and complexation.