As(III) removal by a recyclable granular adsorbent through dopping Fe-Mn binary oxides into graphene oxide chitosan

Huimei Shan; Huinan Mo; Yunquan Liu; Chunya Zeng; Sanxi Peng; Hongbin Zhan

doi:10.1016/j.ijbiomac.2023.124184

As(III) removal by a recyclable granular adsorbent through dopping Fe-Mn binary oxides into graphene oxide chitosan

Int J Biol Macromol. 2023 May 15:237:124184. doi: 10.1016/j.ijbiomac.2023.124184. Epub 2023 Mar 25.

Authors

Huimei Shan¹, Huinan Mo², Yunquan Liu², Chunya Zeng², Sanxi Peng³, Hongbin Zhan⁴

Affiliations

¹ Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area, Guilin University of Technology, Guilin 541004, China; College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China. Electronic address: shanhuimei@glut.edu.cn.
² Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area, Guilin University of Technology, Guilin 541004, China; College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China.
³ College of Earth Science, Guilin University of Technology, Guilin 541004, China.
⁴ Department of Geology & Geophysics, Texas A&M University, College Station 77843, USA. Electronic address: zhan@tamu.edu.

PMID: 36972821
DOI: 10.1016/j.ijbiomac.2023.124184

Abstract

Graphene oxide chitosan composite (GOCS) is recognized as an environmentally friendly composite adsorbent because of its stability and abundant functional groups to adsorb heavy metals, and Fe-Mn binary oxides (FMBO) have attracted increasing interest due to their high removal capacity of As(III). However, GOCS is often inefficient for heavy metal adsorption and FMBO suffers poor regeneration for As(III) removal. In this study, we have proposed a method of dopping FMBO into GOCS to obtain a recyclable granular adsorbent (Fe/MnGOCS) for achieving As(III) removal from aqueous solutions. Characterization of BET, SEM-EDS, XRD, FTIR, and XPS are carried out to confirm the formation of Fe/MnGOCS and As(III) removal mechanism. Batch experiments are conducted to investigate the effects of operational factors (pH, dosage, coexisting ions, etc.), as well as kinetic, isothermal, and thermodynamic processes. Results show that the removal efficiency (R_e) of As(III) by Fe/MnGOCS is about 96 %, which is much higher than those of FeGOCS (66 %), MnGOCS (42 %), and GOCS (8 %), and it increases slightly with the increasing molar ratio of Mn and Fe. This is because amorphous Fe (hydro)oxides (mainly in the form of ferrihydrite) complexation with As(III) is the major mechanism to remove As(III) from aqueous solutions, and it is accompanied by As(III) oxidation mediated by Mn oxides and the complexation of As(III) with oxygen-containing functional groups of GOCS. Charge interaction plays a weaker role in As(III) adsorption, therefore R_e is persistently high over a wide range of pH values of 3-10. But the coexisting PO₄^3- can greatly decrease R_e by 24.11 %. As(III) adsorption on Fe/MnGOCS is endothermic and its kinetic process is controlled by pseudo-second-order with a determination coefficient of 0.95. Fitted by the Langmuir isotherm, the maximum adsorption capacity is 108.89 mg/g at 25 °C. After four times regeneration, there is only a slight decrease of <10 % for the R_e value. Column adsorption experiments show that Fe/MnGOCS can effectively reduce As(III) concentration from 10 mg/L to <10 μg/L. This study provides new insights into binary polymer composite modified by binary metal oxides to efficiently remove heavy metals from aquatic environments.

Keywords: As(III) removal; Chitosan; Fe-Mn binary oxides; Graphene oxide.

MeSH terms

Adsorption
Chitosan*
Hydrogen-Ion Concentration
Kinetics
Oxides / chemistry
Water
Water Pollutants, Chemical* / chemistry
Water Purification* / methods

Substances

Oxides
graphene oxide
Chitosan
Water Pollutants, Chemical
Water