Efficient adsorption of Cu(II) from aqueous solutions by acid-resistant and recyclable ethylenediamine tetraacetic acid-grafted polyvinyl alcohol/chitosan beads

Chitosan (CS)—a natural macromolecule—exhibits various limitations, such as difficult recovery, low mechanical strength, and low adsorption capacity. In this work, to address these shortcomings, polyvinyl alcohol (PVA) was mixed into chitosan beads, thereby improving the mechanical strength and acid resistance of CS. Following this, ethylenediamine tetraacetic acid (EDTA) was introduced to the surface of the mixed beads to fabricate PVA-CS-EDTA, a functionalized adsorbent. Series characterization methods are employed to study the surface morphology, chemical groups, and adsorption strengths of the adsorbents. Moreover, the effects of various adsorption conditions on Cu(II) adsorption are studied. According to the results, the adsorption of Cu(II) by the adsorbent beads follows pseudo-second-order kinetics and the Langmuir adsorption isotherm model. The maximum adsorption capacity of PVA-CS-EDTA is 127.81 mg/g, which is substantially higher than that of the CS beads. In addition, the PVA-CS-EDTA beads remain structurally intact even after treatment with an acidic solution (pH = 2). The higher adsorption capacity and acid resistance of the developed CS are promising for wide applications in the field of adsorption.