ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synthesis and characterization of pectin/carboxymethyl cellulose-based hybrid hydrogels for heavy metal ions adsorption

Sohaib Ahmad, Aneela Sabir, and Shahzad Maqsood Khan

Institute of Polymer and Textile Engineering, University of the Punjab, Lahore, Pakistan

E-mail: sohaib_engineer@outlook.com

Received: 2 September 2022  Accepted: 5 March 2023

Abstract:

Removing heavy metal ions (HMI) from wastewater is essential for improving the quality of aquatic sources for people around the globe. Over the years, several materials have been used as adsorbents for removing HMI from wastewater. The current work aims to remove heavy metals, including copper (Cu), lead (Pb), and nickel (Ni), using biodegradable and cost-effective cellulose-based hydrogels synthesized via solution polymerization. Pectin was cross-linked with carboxymethyl cellulose (CMC) using epichlorohydrin (EPH) to produce superabsorbent hybrid hydrogels (SAHHs) having good stability and structural integrity. The effect of cross-linker content on the swelling behavior of SAHHs was thoroughly studied. Swelling measurements revealed that the hydrogel with 8% (v/v) content of EPH had the highest swelling at room temperature. FTIR, SEM, TGA, DSC, and AFM were used to analyze the morphological characteristics and thermal stability of the SAHHs. Moreover, atomic absorption spectroscopy (AAS) was used to examine the adsorption capacity of the hydrogel at various metal ion concentrations. A parametric analysis was also performed to evaluate the effect of initial metal ion concentration and pH on the HMI adsorption by the best-performing hydrogel in a batch mode. In this regard, the maximum absorption for Cu (II) and Pb (II) was found to be > 99.8%. Whereas for Ni (II), it was > 85% at a metal ion concentration of 0.2 mmol/L. A modeling study revealed that the Freundlich isotherm gave the best fit with experimental results. The amount of adsorbed metal ions calculated from the Freundlich model was 6.19, 4.39, and 3.44 mmol/g for Cu (II), Pb (II), and Ni (II) at pH = 7, respectively. The results demonstrated the successful synthesis of a sustainable and economical adsorbent for removing HMI from wastewater.

Graphical abstract

Keywords: Superabsorbent hydrogel; Pectin; Carboxymethyl cellulose; Epichlorohydrin; Swelling; Copper; Nickel; Lead

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02767-7

Chemical Papers 77 (8) 4165–4177 (2023)