Vol.:(0123456789) 1 3 Journal of Bio- and Tribo-Corrosion (2020) 6:10 https://doi.org/10.1007/s40735-019-0303-z Plant Extracts as Efective Additives in Zinc Electroplating on Mild Steel Cleophas Akintoye Loto 1,2  · Roland Tolulope Loto 1  · Abimbola Patricia Popoola 2 Received: 10 May 2019 / Revised: 31 October 2019 / Accepted: 11 November 2019 © Springer Nature Switzerland AG 2019 Abstract This investigation examines and reviews the electroplating of zinc on mild steel in acid chloride solutions (ZnCl, KCl and H 3 BO 4 ). Extract concentrations of Nicotiana tobaccum, Ananas comosus, Saccharum officinarum and Allium cepa were used as additives. Experimental factors employed include variation in plating time, extract additive concentrations and fxed pH conditions. A DC power supply at defned operating parameters was used for the electroplating. Examination of the plated steel surface was done with scanning electron microscopy. Elemental composition analysis was performed with energy dispersive spectroscopy. Variation in surface characteristics was obtained with respect to concentration of the addi- tive and plating time. Corrosion resistance of the steel-plated surface was determined by gravimetric method. The surface microstructural morphology of the plated metal showed good zinc electroplating quality. Keywords Electroplating · Plants extracts · Steel · Acid chloride · Corrosion 1 Introduction The need to protect from corrosion and wear, prolong life and enhance the aesthetic appearance/value of metallic components/products has continued to generate scientifc research interest in electroplating [1–14]. The research inter- est also extends to the use of additives in electroplating. Additives from organic chemical compounds, such as thio- sulphate, dextrin, glucose and glycine had been extensively used [15–20]. However, very recently there has been further interest in the use of plant extracts (leaves, fruits) as addi- tives in electroplating and these are environmentally friendly [21–27]. Extracts that have been used as efective additives on the electroplating of zinc on mild steel in zinc chloride solution include Saccharum officenarum, Ananas comosus, Allium sativum, Nicotiana tabacum, Manihot esculenta and Allium cepa. In some cases, the synergism of the above men- tioned extract additives has also been investigated [28–31]. The results obtained have been relatively good depending on the experimental variables such as the plating time, pH and additive concentrations. It is important to state here that these extract additives are of various complex chemical constituents/compositions that could act either as stabilis- ers, whiteners, or levellers that could infuence the surface morphology of the electroplated substrate surface. One of such constituent structures is shown Fig. 1. On analysis [32], Allium cepa chemical constituents include vitamin C, Vita- min B6, folic acid and other nutrients in trace forms. Other chemical compounds in Allium cepa are phenolics and fa- vonoids [33, 34] which include quercetin and its glycosides; quercetin 3, 4-diglucoside and quercetin-4-glucoside. Ananas comosus has diverse constituents that include car- bohydrates, sugars, sucrose, fructose, glucose, ash, vitamins A and C, and phytonutrients (carotene-ß and crypto-xanthin- ß), manganese, and vitamin B [35, 36]. Other constituents available are protein, dietary fbre, folates, niacin, pyridox- ine, ribofavin, thiamine, vitamin E and vitamin K. Minerals such as Na, K, Ca, Cu, Fe, Mg, P, Se and Z are also con- tained. Ananas comosus also contain antioxidants, namely favonoids and the enzyme bromelain [37]. Saccharum offici- narum juice consists of soluble substances like sucrose, fne particles of bagasse, wax, clay, colouring matter and albu- men. Chemically, it contains glucose and fructose, vitamin B2, potassium and about 70% of H 2 O [34, 35]. Nicotiana * Roland Tolulope Loto tolu.loto@gmail.com 1 Department of Mechanical Engineering, Covenant University, Ota, Nigeria 2 Department of Chemical, Metallurgical & Materials Engineering, Tshwane University of Technology, Pretoria, South Africa