Preparation and characterization of new foam adsorbents of poly(vinyl alcohol)/chitosan composites and their removal for dye and heavy metal from aqueous solution

A novel composite foam of poly(vinyl alcohol) (PVA) and chitosan (CS), i.e. PVA/CS composites, was prepared as an adsorbent for the removal of malachite green (MG) and Cu2+ from aqueous solution. The PVA/CS composite foam held the advantages of PVA and CS. The introduction of CS improved significantly the adsorption capacities of Cu2+ and MG. The resulting foam with the interconnected pores exhibited good mass transfer property, processing properties and stability. Meanwhile, PVA/CS foam adsorbents had been proved with the excellent adsorption and fast kinetics for MG and Cu2+. However, MG and Cu2+ in binary system exhibited competitive adsorption. The adsorption isotherms, kinetics and thermodynamics of PVA/CS foams for MG and Cu2+ were studied in detail, moreover, the effects of ionic strength and foreign pollutants were also investigated. Additionally, desorption and reusability of PVA/CS foam was also investigated based on sequential adsorption–desorption cycles. PVA/CS foam adsorbents could simultaneously remove MG and Cu2+ when they existed at low concentrations (<100 mg/L). All the studied results indicated that PVA/CS composite foam was an efficient, low cost and reusable adsorbent for removal of MG and Cu2+ from aqueous solutions due to its simple preparation, high adsorption capacity, fast adsorption rate, ionic strength independence, easy separation and good reusability. These properties are of potential application in the up-flow adsorption column for the removal of organic dye and heavy metal.

► Novel PVA/chitosan (CS) composite foams were prepared by IPN and foaming process.
► PVA/CS foams with macroporous structure showed good mass transfer performance and stability.
► High capacity, fast rate and ionic strength independence for malachite green and Cu2+ removal.
► Novel adsorbents were easily separated and reused, which reduced the operation cost.
► Simultaneous removal of dye and Cu2+ could reduce energy consumption and cost in application.