Simultaneous removal of heavy metal ions by a sulfonic acid-functionalized melamine-based covalent organic framework: optimization by response surface methodology

Abstract

Over the past decade, covalent organic frameworks (COFs) have been increasingly utilized as porous crystalline materials for removing or adsorbing various types of pollutants from aqueous solutions. In this study, we introduce a sulfonic acid-functionalized melamine-based COF (COF@SO₃H) as a highly effective and efficient adsorbent for the removal of Cd(II), Cu(II), Pb(II), Ni(II) and Zn(II) ions from aqueous media. An ideal experiment was conducted using the response surface method (RSM) based on the Box Behnken design (BBD) model to investigate the effects and interactions of different parameters. Under optimum conditions, the maximum adsorption capacities of the COF@SO₃H adsorbent toward the target ions were in the range of 59.52–70.42 mg g⁻¹. The adsorption isotherms, kinetics, and reusability of the prepared COF@SO₃H were comprehensively studied. The results indicate that the prepared COF can potentially serve as a cost-effective, highly efficient, and reusable adsorbent for removing heavy metal ions from environmental water and wastewater samples.