Efficient removal of mercury ions with MoS-nanosheet-decorated PVDF composite adsorption membrane.

The exploitation of a new adsorbent with a high adsorption performance and recyclability is of great practical significance for the treatment of wastewater containing mercury ions. In this study, a novel membrane adsorbent was fabricated by blending MoS nanosheets into a PVDF polymer matrix (P-PVDF/MoS) followed by non-solvent-induced phase conversion. This material was able to bind mercury ions and was not affected by the solution ionic strength, co-existing anions, or interfering heavy metal ions. The optimal pH range for mercury ion elimination was 4.5-6.0, and P-PVDF/MoS exhibited a maximum adsorption capacity of 578 mg g. The pseudo-second-order adsorption kinetics and Langmuir isotherm models best described the adsorption process. The adsorption mechanism was mainly monolayer chemisorption, for which the S groups were the major active sites. Furthermore, the membrane could be removed from the aqueous solution easily using tweezers, and the removal efficiency of mercury ions remained over 90% after ten cycles. This study suggests that the inexpensive and recyclable P-PVDF/MoS membranes can be used for the efficient removal of heavy metal ions from wastewater at a large scale.