Colloids and Surfaces A: Physicochem. Eng. Aspects 260 (2005) 145–155 Voltammetric and FT-IR studies of modified activated carbon systems with phenol, 4-chlorophenol or 1,4-benzoquinone adsorbed from aqueous electrolyte solutions M. Pakula a , A. ´ Swi˛ atkowski b , M. Walczyk c , S. Biniak c,∗ a Naval University of Gdynia, 81-103 Gdynia, Poland b Military Technical Academy, Institute of Chemistry, ul. Kaliska 2, 00-908 Warsaw, Poland c N. Copernicus University, Faculty of Chemistry, ul. Gagarina 7, 87-100 Toru´ n, Poland Received 4 October 2004; accepted 23 March 2005 Available online 17 May 2005 Abstract Cyclic voltammetric and spectral FT-IR studies of the influence of surface chemistry on the adsorption and electrochemical be- haviour of powdered activated carbon electrodes (PACE) in the presence of phenol, 4-chlorophenol and 1,4-benzoquinone were car- ried out. The variety of surface chemical properties was achieved through modification of the carbon samples by heat treatment un- der vacuum and in an oxygen–ammonia atmosphere as well as by oxidation with conc. nitric acid. Adsorption processes were carried out from aqueous solutions (in air and an oxygen-free atmosphere) in the presence acidic, neutral or basic electrolytes. Some elec- trochemical parameters of electrode systems with adsorbed organics were estimated and correlated with the adsorption ability of car- bon materials. The changes in FT-IR spectra of the carbons caused by adsorption and/or coupling organic molecules are presented and discussed. © 2005 Elsevier B.V. All rights reserved. Keywords: Adsorption organic molecules; Cyclic voltammetry; FT-IR spectroscopy 1. Introduction Phenol and substituted phenols are a major class of or- ganic pollutants that contaminate the ecosystem and accu- mulate in the food chain [1–3]. Treatments of drinking water for the removal of organic impurities have attracted special attention in environmental science and technology. Several methods are used for municipal water purification, mainly filtration processes with the application of various high-area adsorbents (e.g. granular activated carbon) [4–7]. The pres- ence of molecular oxygen in an adsorption system can im- prove the ability to adsorb phenol and some its derivatives [7–10]. On the other hand, the presence of oxygen-containing surface functional groups can also changes the adsorption ∗ Corresponding author. Tel.: +48 56 611 4549. E-mail address: sbiniak@chem.uni.torun.pl (S. Biniak). ability of carbon materials [4–10]. In recent years, a di- rect electrochemical oxidation process for phenolic pollu- tant removal has been proposed and studied. However, a key problem arising during these processes is the deactiva- tion of the carbon adsorbent/electrode surface [11–13]. In the electrochemical process, oxidation of phenols and/or de- position of the oxidation products can occur. It has been shown that the activity of the carbon electrode in phenol electro-oxidation is considerably less during the second and next cycles of voltammetric measurements [14–18]. There- fore, studies of the phenomena occurring at an aqueous solution/activated carbon electrode interface are necessary in order to gain an understanding of these processes. The aim of the present work was, therefore, to study the in- teraction between activated carbon surfaces and adsorbed phenol derivatives using electrochemical and spectral methods. 0927-7757/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.colsurfa.2005.03.013