Materials Chemistry and Physics 112 (2008) 478–484 Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys Preparation of iron-deposited graphite surface for application as cathode material during electrochemical vat-dyeing process M. Anbu Kulandainathan ∗ , K. Kiruthika, G. Christopher, K. Firoz Babu, A. Muthukumaran, M. Noel Electro-organic Division, Central Electrochemical Research Institute, Karaikudi 630006, India article info Article history: Received 13 March 2008 Received in revised form 28 May 2008 Accepted 4 June 2008 Keywords: Surfaces Electrochemical techniques Electrochemical properties Microstructure abstract Iron-deposited graphite surfaces were prepared, characterized and employed as cathode materials for electrochemical vat-dyeing process containing very low concentration of sodium dithionite. The elec- trodeposition, in presence of ammonium thiocyanate and gelatin or animal glue as binding additives, were found to give finer iron deposits for improved electrochemical dyeing application. The electrode- posits were characterized using scanning electron microscopy, electron-dispersive X-ray spectroscopy and X-ray diffraction methods, before and after electrochemical dyeing process. The electrochemical activity of the iron-deposited graphite electrodes always stored in water seems to depend on the surface-bound Fe 3+ /Fe 2+ redox species. Vat dyes like C.I. Vat Violet 1, C.I. Vat Green 1 and C.I. Vat Blue 4 could be efficiently dyed employing these above electrode materials. The colour intensity and washing fastness of the dyed fabrics were found to be equal with conventionally dyed fabrics. The electrodes could also be reused for the dyeing process. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Eliminating or minimizing the use of sodium dithionite and other sulphur-containing compounds during the vat-dyeing pro- cess is an important challenge in environmental chemistry. Among them, chemical, electrochemical and biochemical alternative approaches are under investigation [1–5]. Direct electrochemical reduction in the vat-dyeing bath itself is of important due to its sim- plicity and ease of incorporation into the conventional dyeing bath. In some recent studies, Roessler et al. have reported direct electro- chemical reduction of vat dye using electrodeposited Ni cathodes [6,7]. Direct reduction using other solid electrodes like Ti, Cu, Ni, and stainless steel has also been reported [8,9]. High cathode sur- face area could be achieved using graphite granules as well as chemically modified graphite granules as fluidized bed cathodes for vat molecule reduction [10,11]. Recently Bechtold et al. demon- strated the direct reduction of oxidised C.I. Sulphur black 1 by means of multi-stainless steel cathode electrolyser [12,13]. Cathode processes such as hydrogen evolution at iron alloys [14], reduction of organic compounds [15] and dehalogenation processes at iron metal particles [16,17] have been reported. Iron or electrodeposited iron cathode have not been employed so far as cathode material in electrochemical dyeing process. ∗ Corresponding author. Tel.: +91 4565 227772; fax: +91 4565 227779. E-mail address: manbu123@yahoo.com (M. Anbu Kulandainathan). In some recent studies ammonium thiocyanate as an additive was found to be useful in preparing fine iron deposits on silicon sur- faces [18]. Electrodeposition on platinum substrate from sulphate bath has also been reported [19]. Saccharides and gelatin enhance the adhesion of iron deposits [20,21]. Based on these investigations, electrodeposition of iron on graphite substrate is reported in the present work. A useful role of ammonium thiocyanate as well as other additives in the electrodeposition process is also reported. The electrodeposited graphite was employed in the electrochemi- cal dyeing process. The influence of electrodeposition condition on the overall efficiency of vat-dyeing process was also evaluated. 2. Experimental details 2.1. Chemicals Technical-grade chemicals of sodium dithionite, ferrous sulphate, ammonium sulphate, sodium hydroxide, ammonium thiocyanate, animal glue and gelatin were purchased from Fischer, India. All aqueous solutions were prepared with deionised water. Vat dyes like C.I. Vat Violet 1 (Novinone Brill Violet RR), C.I. Vat Green 1 (Novinone Green FFB) and C.I. Vat Blue 4 (Novinone Blue RSN) were supplied by Novaltic, India and used as received. 2.2. Cyclic voltammetric studies For voltammetric studies, a BAS IM6 Electrochemical Analyser (USA) was employed with a platinum foil as counter electrode and homemade Hg/HgO/OH - (1 M) as reference electrode. In a conventional three-electrode system, 3-mm diam- eter glassy carbon (GC) was used as the working electrode for electrodeposition studies (Section 3.1). Plane graphite and iron-deposited graphite electrode were 0254-0584/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2008.06.010