Facile synthesis and characterization of Chromium(III)/Zirconium(IV) impregnated Chitosan/β-Cyclodextrin Bio-composite and Application towards efficient removal of Copper(II) from aqueous systems

Abstract

• Synthesis of Cr(III)/Zr(IV) impregnated chitosan-β-cyclodextrin bio-composite (CB@CZ) and characterization. • At pH 5, CB@CZ compound efficiently adsorbs Cu(II) from an aqueous solution. • At optimum conditions, CB@CZ has a high monolayer saturation capacity of 76.47 mg g -1 for Cu(II). • kinetic data agree well with the pseudo-second-order equation, implying the chemisorption mechanism. • Ion-exchange cum electrostatic attraction mechanisms have been hypothesized for Cu(II) adsorption onto the adsorbent. Chromium(III)/zirconium(IV) impregnated chitosan-β-cyclodextrin bio-composite (CB@CZ) was fabricated successfully by a simple chemical method. The synthesized NC is characterized by analytical tools such as FT-IR, PXRD, FESEM, TEM, EDS, BET, TGA, etc. Application of as-prepared material selectively adsorb Cu(II) over other metal ions from water has been investigated in varying different parameters. The pH is optimized between 5.0 and 6.0 and kinetic data agree well with the pseudo-second-order equation. The isotherm data agree better with the Freundlich, Redlich-Peterson and Dubinin-Radhuskevich models than the Langmuir. Thermodynamics studies indicate that the adsorption process is endothermic but spontaneous and Cu(II) adsorption occurs with increasing entropy. The spontaneity of this surface adsorption is more favorable at higher temperatures. The adsorption mechanisms suggest that Ion-exchange as well as electrostatic attraction process occurred. The Cu(II) adsorption is dominated by the hydroxyl and amino functional groups of β–cyclodextrin and chitosan. Overall, the CB@CZ has tremendous potential in removing Cu(II) for practical applications from contaminated wastewater due to its green synthesis technique, selectivity, and strong adsorption capability.