Bioremoval of mercury (II) from aqueous solutions by Phragmites australis: Kinetic and equilibrium studies

Abstract

In this study, the removal of mercury (II) ions from aqueous solutions by dried biomass of Phragmites australis was investigated in the batch system. The biomass was characterized by Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray fluorescence (ED-XRF), Brunauer–Emmett–Teller (BET) surface area techniques (BET). Inductively Coupled Plasma Atomic Emission Spectrophotometer (ICP-OES, Spectro Blue) was used to analyze Hg(II) concentration and obtained data in batch experiments indicated that Hg (II) was rapidly adsorbed and such adsorption reached equilibrium within 60 min. The initial pH of the solution was effective parameter for Hg (II) biosorption. The biosorption kinetics was in better good fit with pseudo-second order kinetics and the results obtained from the batch experiments were conformed better with the Langmuir isotherm model than Freundlich and D-R isotherm models. The maximum Hg (II) biosorption capacity of P.australis was 20.0 ± 0.4 mg/g. The availability of other metal ions affected mercury biosorption. Adsorption/desorption studies demonstrated that the adsorbed Hg (II) could be desorbed effectively with a 0.1 M ethylenediamine tetra-acetic acid (EDTA) solution. The biosorption capacity of the regenerated biosorbent could still be maintained at 72% at the fifth adsorption–desorption cycle. Consequently, it can be said that P. australis can be used as an applicable, cost-efficient, nature friendly biosorbent for treating wastewater.

Graphical Abstract

Keywords::

• Aquatic plants
• adsorption
• mercury (II)
• isotherm
• kinetic

Acknowledgement

The authors would like to extend their thanks to Kırıkkale University Research Fund for their financial support, Project number: 2017/056.