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

Organic and inorganic acids-functionalized CNTs for the adsorption of Cu²⁺ and Ni²⁺ ions from aqueous solution

Maheen Gull, Shahzad Hussain, Ayesha Tariq, Zubaah Khalid, Fozia Bibi, and Muhammad Waseem

Department of Chemistry, COMSATS University Islamabad, Islamabad, Pakistan

E-mail: waseem_atd@yahoo.com

Received: 26 March 2023  Accepted: 18 June 2023

Abstract:

Heavy metals like copper and nickel are highly toxic due to their non-biodegradable and carcinogenic nature. In this study, adsorption technique was used to remove these undesired heavy metals from aqueous solutions. Carbon nanotubes (CNTs) due to fascinating member in carbon family are selected as an adsorbent which was further functionalized by citric acid and sulfuric acid. The morphological and structural properties of CNTs before and after functionalization were studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray (EDX) spectroscopy. Batch adsorption method was applied to investigate the adsorption of Cu²⁺ and Ni²⁺ ions on bare and acid-functionalized CNTs. The equilibrium concentration of Cu²⁺ and Ni²⁺ ions was determined by atomic absorbance spectroscopy. The respective maximum adsorption capacity for Cu²⁺ ions by CNTs, SA-CNTs and CA-CNTs was 13.19, 25 and 65.35 mg/g, whereas for Ni²⁺ ions these were 14, 33 and 40 mg/g. The thermodynamic parameters like ΔH, ΔS and ΔG were also calculated by using van’t Hoff equation. The adsorption data was compared with the previous findings, and the results showed that acid-functionalized CNTs are more effective than bare CNTs for the adsorption of Cu²⁺ and Ni²⁺. Finally, the adsorbent recovery was ensured by desorption study of metal ions by using pre-sorbed Cu²⁺ and Ni²⁺ ions.

Keywords: Adsorption; CNTs; Copper; Functionalization; Nickel

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02955-5

Chemical Papers 77 (11) 6519–6531 (2023)