Designing a 3D-MoS2 nanocomposite based on the Donnan membrane effect for superselective Pb(II) removal from water

Abstract

Developing more practical and efficient adsorbents is highly desirable for lead purification. Although MoS2 nanosheets have an excellent affinity for lead ions, their narrow layer spacing and ultrafine size hinder their scaled-up application. Herein, a novel type of 3D nanocomposite, W-MoS2@SCA, was synthesized by confining MoS2 nanoparticles with widened interlayer spacing (W-MoS2) in the networking pores of sulfonated cellulose aerogel (SCA). The excellent hydraulic property provided by the porous host overcomes the shortcomings of MoS2 nanomaterials and makes the composite have a satisfactory treatment effect in the flow-through system. Combined with the Donnan membrane effect produced by the positively charged sulfonic group of the host and the excellent affinity of MoS2 for lead ions, W-MoS2@SCA exhibits rapid adsorption kinetics (75 min to reach adsorption equilibrium) and superselectivity for Pb2+ removal. The distribution coefficient for Pb2+ is up to 1.01 × 105 mL/g even in complex wastewater mixed with multiple metal ions. Fixed-bed column tests indicate that an efficient application is achieved with a treatment capacity of 9000 kg wastewater/kg sorbent based on the wastewater discharges of China. Specifically, residual Pb2+ in the first 7000 kg effluent was virtually undetectable. In addition, the exhausted sorbent could be easily regenerated by the NaCl-Na2EDTA binary solution and maintained good reusability without significant capacity loss after 10 adsorption–desorption cycles. The results demonstrate that W-MoS2@SCA has great potential for use in deep purification for lead sequestration in advanced wastewater treatment.