Removal of lead ions by two FeMn oxide substrate adsorbents

• Published in: The Science of the total environment Vol. 773; p. 145670
• Main Authors: Chen, Danni, Li, Daguang, Xiao, Zhenjun, Fang, Zheng, Zou, Xuegang, Chen, Ping, Chen, Tiansheng, Lv, Wenying, Liu, Haijin, Liu, Guoguang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.06.2021
• Subjects: Adsorption mechanism; Fe-Mn; Lead ion; Tannic acid film; Lead ion; Tannic acid film; Fe-Mn; Adsorption mechanism
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.145670

Lead pollution has become a global concern due to its ubiquity and persistence. This study describes two FeMn oxide substrate adsorbents, namely, FeMn binary oxides (FMBO) and mesoporous FeMn binary oxide (MFMBO) covered with tannic acid film (FMBO@TA-Fe3+ and MFMBO@TA-Fe3+), for the treatment of Pb2+ in water. The characterization results showed that TA was successfully coated onto the surfaces of FMBO and MFMBO. The maximum capacities of Pb2+ on FMBO@TA-Fe3+ and MFMBO@TA-Fe3+ were 322.08 and 357.14 mg g−1, respectively, which were twice those of FMBO and MFMBO. The adsorption of Pb2+ on the adsorbents was a spontaneous, endothermic process with increasing disorder through thermodynamics studies. An overall mechanism was proposed for Pb2+ adsorption, the improved adsorption performance of FMBO@TA-Fe3+ and MFMBO@TA-Fe3+ is ascribed to the mesoporous characteristics and the introduction of hydroxyl groups. Further investigation indicated the adsorption of Pb2+ could be attributed to electrostatic interactions on FMBO@TA-Fe3+ and MFMBO@TA-Fe3+, and cation exchange existed through the formation of these internal surface complexes. The Pb2+-loaded adsorbents could be effectively desorbed in a dilute hydrochloric acid solution, promoting recycling and reuse of the regenerated adsorbents. These results warrant the promising application of FMBO@TA-Fe3+ and MFMBO@TA-Fe3+ for the removal of Pb2+, and this work first proposed TA film-modified FMBO and MFMBO to improve its adsorption capacity in the application of environmental remediation. [Display omitted] •Tannic acid covered with FeMn binary oxide was fabricated in the first time.•The adsorbents exhibited excellent adsorption Pb2+ performance.•The adsorption mechanisms were electrostatic interactions and cation exchange.•The two FeMn oxide substrate adsorbents had excellent stability and reusability.