Surface modification of Dendrocalamus strictus charcoal powder using nitrilotriacetic acid as a chelating agent and its application for removal of copper(II) from aqueous solutions

Abstract

ABSTRACT In the modern era, copper toxicity has become progressively more common due to widespread applications of copper in metallurgy, plumbing, transportation, and electrical wiring industries which demands the development of economic methods for removal of copper(II) ions from various industrial/domestic effluents before their disposal. In this study, nitrilotriacetic acid-modified Dendrocalamus strictus charcoal powder (NTA-MDCP) was prepared and applied as an adsorbent for the removal of copper(II) ions from aqueous solutions. Batch mode adsorption experiments were performed to achieve the optimum adsorption parameters such as pH = 6, contact time = 2 h, adsorbent dose = 2 g/L. The adsorption data were analyzed using Langmuir, Freundlich, and Temkin isotherm models. Maximum adsorption capacity of NTA-MDCP for copper(II) ions from Langmuir isotherms was found to be 142.86 mg/g which may be attributed to affinity of NTA present on the surface of adsorbent toward 1:1 and 2:1 complex formation with copper (II) ions in solution. Thermodynamic studies of adsorption of copper (II) ions indicated the spontaneous and endothermic nature of adsorption process which was confirmed by negative ΔG (= −15.309 to −23.995 kJ/mol) and positive ΔH (= +3.719 to +63.119 kJ/mol) values, respectively, while kinetic study revealed that the adsorption process followed pseudo-second order. Before and after adsorption, surface characteristics of NTA-MDCP were examined using scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), Brunauer-Emmett-Teller (BET), carbon, hydrogen, nitrogen, and sulfur (CHNS) and X-ray diffraction (XRD) and the results obtained confirmed the accumulation of copper(II) ions on the surface of adsorbent. Regeneration of adsorbent was successfully carried out by the desorption process using calcium chloride solution (CaCl2: 5g/L). The present study revealed that NTA-MDCP could serve as a good adsorbent for the removal of copper(II) ions from aqueous solution certainly due to the chelating capacity of NTA.