Study On Adsorption Performance Of Modified Polyacrylonitrile Nanofiber Membrane For Pb²⁺ And Methylene Blue In Water

The nanofiber membrane prepared by the electrospinning technology has a large specific surface area,high porosity and a special grid structure,which has good application prospect in the fields of adsorption and removal of pollutants.In this paper,Polyacrylonitrile/Hydroxyapatite and Polyacrylonitrile/?-cyclodextrin nanofiber membranes were prepared by blending doped?-cyclodextrin and hydroxyapatite with excellent adsorption characteristics using polyacrylonitrile as raw material.Its adsorption properties and mechanisms for Pb²⁺and Methylene Blue in aqueous solution were discussed.?1?The polyacrylonitrile/?-cyclodextrin nanofiber membrane?PAN/?-CD?prepared by electrospinning had the best adsorption effect when the mass ratio of PAN and?-CD is 8:2.Under the condition that the pH of solution was 8.0 and adsorbent dosage was 1.0g/L,the adsorption capacity of MB solution at a concentration of 100mg/L was 70.80 mg/g.which was 3.49 times higher than the adsorption capacity of MB by pure PAN nanofiber membrane under the same conditions;under the conditions that the pH of solution was 5.5,and the amount of the adsorbent added was 2.0g/L,the adsorption capacity of the Pb²⁺solution with a concentration of 200 mg/L is 48.89mg/g.which was 3.84 times higher than the adsorption capacity of Pb²⁺by pure PAN nanofiber membrane under the same conditions.?2?Nano-hydroxyapatite?HAP?was prepared by co-precipitation method,and the polyacrylonitrile/hydroxyapatite nanofiber membranes?PAN/HAP?were prepared by electrospinning.It had the best adsorption effect When the mass ratio of PAN and HAP was 7:3.Under the condition that the pH of solution was 5,the dosage of the adsorbent is 1.0g/L,the adsorption capacity of the MB solution with a concentration of 80mg/L and the Pb2+solution with a concentration of 400mg/L were 62.44mg/g and 111.92mg/g respectively.which was 3.08 and 8.79 times higher than the adsorption capacity of MB and Pb²⁺by pure PAN nanofiber membrane under the same conditions.?3?The adsorption of Pb²⁺and MB by PAN,PAN/?-CD and PAN/HAP nanofiber membranes complies with the quasi-second-order adsorption kinetic model and Langmuir isothermal adsorption model.The adsorption of MB by PAN/?-CD membrane mainly depends on the inclusion by the cavity structure of?-CD and electrostatic attraction of MB;the adsorption of Pb2+by PAN/HAP membrane mainly depends on the ion exchange of HAP and Pb²⁺and Coordination effect of hydroxyl on Pb²⁺.?4?the adsorption capacity of Pb²⁺by PAN,PAN/?-CD and PAN/HAP nanofiber membranes could reach 30.28%,62.50%and 82.26%of the initial adsorption capacity after five times reusing,respectively;and the adsorption capacity of MB could reach42.16%,72.52%and 60.40%of the initial adsorption capacity,respectively.