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

DC and DP polarographic studies to explore the intermediate species form and operating conditions effects on electrodeposition of Cu from Cu(II) in the presence of alizarin red S

Nour Mohammad-Sadik Ali, Suresh Vemuri, Dharini Bhagat, Ayman Karam, Ranjan Pati, Abhijit Ray, and Indrajit Mukhopadhyay

Department of Solar Energy, School of Technology, Pandit Deendayal Energy University; PDEU, Gandhinagar, India

E-mail: nour_ragif@hotmail.com

Received: 11 October 2021  Accepted: 16 November 2021

Abstract:

The reduction of Cu(II) has been investigated in the presence of Alizarin Red S in two different background solutions namely KCl and acetate buffer through this study. The electroactive intermediate species have been extensively characterised by using Direct Current Polarography and Deferential Pulse Polarography techniques. It has been observed that Cu²⁺ was reduced to elemental copper in a two-step single-electron transfer process. However, the kinetics of charge transfer is dampened in the presence of Alizarin due to the complexation of active copper ions with ionised Alizarin, making the electrodeposition more controlled. In the first technique, the peaks of the 57 mM-Cu²⁺ reduction and for the 57 mM-Alizarin reduction have been observed. Using the second technique, the voltammograms exhibit the peaks at pH = 2, 3, where the first peak is for the reduction process of two carbonyl groups in Alizarin, and the second one is for Cu²⁺ reduction as one-step two-electron transfer. At pH = 5, the complex formation reveals that copper can be hardly reduced on the cathode, whereas Alizarin has two small peaks for two carbonyl groups after being in the investigated alkali mediums. The clear peak at pH = 11 indicates that copper is no more in the structure of a complex. The stoichiometries of the salt and complex have been also verified where both are (1:1). Coating experiments were carried out at 25 °C, 35 °C and 60 °C to investigate the relations between the current efficiency and pH, current density, molarity concentration and time and obtain the optimal operating conditions for copper electrodeposition on steel and stainless steel.

Keywords: Alizarin red S; Copper Cu(II); Electrodeposition; Direct current polarography; Deferential pulse polarography

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01988-y

Chemical Papers 76 (3) 1745–1766 (2022)