Abstract

Understanding the kinetics of high-purity zero-valent copper production via galvanic displacement process has crucial implications for numerous industrial applications and the development of new cost-effective technologies. This study presents a novel approach to galvanic copper deposition using carbon steel chips and powders as reducing agents. The effects of milling time, used to prepare activated carbon steel powders via high-energy ball milling, and solution acidity on the kinetics and morphological attributes of the deposited copper were investigated. Notably, the galvanic process exhibited a significant dependency of the copper and iron reaction kinetics on both the initial state of the carbon steel (chips or powders) and the acidity of the solution, which was also influenced by the hydrogen evolution reaction as secondary reaction. The most favorable conditions for galvanic deposition were achieved employing carbon steel powders in acidic solutions, enabling rapid copper deposition in less than 5 min, with purities ranging between 90 and 94 %. In contrast, carbon steel chips required reaction times longer than 30 min. Meanwhile, the copper galvanic deposition was not completely evident in solution of natural acidity by using carbon steel powders, due to the formation of a passivating barrier on the carbon steel surface. Experimental results indicated that the reaction rate follows a global second-order kinetics. Scanning electron microscopy, X-ray diffraction, and Raman spectroscopy analysis corroborated the results.