Polydopamine coating assisted synthesis of MnO2 loaded inorganic/organic composite electrospun fiber adsorbent for efficient removal of Pb2+ from water

Polydopamine (PDA) and MnO2 have been proven to be promising adsorbents to capture Pb2+ from wastewater. In this study, MnO2 was in-situ loaded onto flexible electrospun polyacrylonitrile (PAN) fibers by the assistance of polydopamine coating (MnO2/PDA/PAN fibers) and the as-obtained MnO2/PDA/PAN fibers were utilized for the removal of Pb2+ from water. The structure and chemical composition of MnO2/PDA/PAN fibers were characterized in detail. The results indicated that the PDA coating onto PAN fibers can't be neglected for loading MnO2. This preparation of MnO2/PDA/PAN fibers could avoid the agglomeration of MnO2 particles and make the adsorbent separate easily from the adsorption solution. The adsorption experiments showed that the adsorption process toward Pb2+ by MnO2/PDA/PAN fibers followed pseudo-second-order model and Langmuir isotherm model. In comparison with PDA/PAN fibers and MnO2/PAN fibers, MnO2/PDA/PAN fibers showed higher Pb2+ adsorption capacity. The maximum adsorption capacity calculated from Langmuir model was 185.19 mg/g, which is higher than most of the reported PDA or MnO2 based Pb2+ adsorbents. The adsorption toward Pb2+ by MnO2/PDA/PAN fibers still maintained stability after five adsorption/desorption cycles. In addition, the fiber adsorbent could also adsorb Pb2+ from real industrial effluent with removal efficiency above 95%. This work indicates that MnO2/PDA/PAN fibers have great potential to be used as effective adsorbents for practical Pb2+ removal.