Adsorption of Alkali Blue, Metanil Yellow and Neutral Red dyes Using Copper (II) Oxide particles: Kinetic and Thermodynamic Studies

Abstract

Copper (II) oxide particles (CuO-Ps) was synthesized and used for the removal of Metanil Yellow (MY), Alkali Blue (AB) and Neutral Red (NR). The influence of variables such as contact time, dosage, temperature and agitation speed for the adsorption process were investigated using Batch Adsorption Method. The synthesized particles were characterized using UV-Visible spectroscopy with a broad peak of 273 nm indicating the change
in colour of the CuO-Ps from blue to brownish black with the formation of CuO-Ps. FTIR were carried out to determine the functional groups present at the surface of the particle with functional groups such as –OH, C=C, C-H, C≡C detected. SEM analysis of the CuO-Ps was carried out. The changes in the morphology was observed which is due to the attachment of the dye molecules at the surface of the particles. The percentage removal and optimum contact time of MY, AB and NR were obtained as 70.7% at 25 min, 84.8% at 10 mins and56.9% at 30 min respectively. Kinetics studies of all the dyes shows that adsorption process fits pseudo second order with the experimental values of qe 2.844, 4.242 and3.536 for NR, AB and MY respectively being closer to the calculated values of the qe 2.739, 4.108 and3.222 for NR, AB and MY respectively. Non linearity from Bangham’s plot shows that both film and pore diffusion played an important role in all the three adsorption processes. Negative values of ΔH andΔG revealed that the process was exothermic and feasible. Positive and Negative values for ΔS showed spontaneity of the process and decrease in randomness. Values of ΔH -6.70, -20.30 and-7.76 kJ/mol for AB, NR and MY, respectively confirmed the adsorption process as physical in nature. The results indicated that copper (II) oxide particles can be used as a low cost adsorbent for the removal of MY, AB and NR from aqueous solutions.

Keywords: Adsorption, CuO, FTIR, Kinetic, SEM, Thermodynamics, UV-Visible spectroscopy