Study of Cu(II) Chemisorption Mechanisms on Modified Carbon Nanotubes Based on Isotherms, Column Experiments, and FTIR First Derivative Analysis Shirley Rosenzweig & George A. Sorial & Endalkachew Sahle-Demessie & Todd Luxton Received: 30 January 2015 /Accepted: 4 June 2015 # Springer International Publishing Switzerland 2015 Abstract The objective of this study was to investigate the chemisorption mechanisms of Cu(II) on alcohol functionalized carbon nanotubes (OH-CNT) compared to granulated activated carbon (F-400). Two different sizes of OH-CNT were used on both adsorption iso- therm experiments and continuous-flow fixed-bed col- umns. The experiments were conducted as a function of adsorbent type with fixed bed height (5 cm), fixed flow rate (0.035 mL/min), and one initial Cu(II) concentra- tion (10 mg/L) at pH 5.1 and room temperature. Isotherm curves follow Freundlich model with better adsorption capacity for OH-CNT (6.3 and 15.7 mg/g) compared to F-400 (6.0 mg/g). Breakthrough curves for all adsorbents were typical, while OH-CNT showed higher capacity to treat water per amount of adsorbent than F-400. After 5 days of desorption, there was very little Cu(II) leached from the OH-CNT column as com- pared to F-400 that slowly desorbed 85 % of Cu(II). These results indicated chemisorption process on OH- CNT with low residual release of Cu(II) from adsorbent after reaching saturation. A systematic correlation meth- od using converted FTIR absorbance curves (first deriv- ative analysis) of as-received and hybrid OH-CNT iden- tified new peaks on the spectra for Cu(II) chemisorbed on CNT surface, showing that Cu(II) target acidic func- tional groups during adsorption. Keywords Adsorption . Breakthrough . Carbon nanotubes . Chemisorption . Copper . Fixed-bedcolumn . IR first derivative analysis 1 Introduction Carbon nanotubes (CNT) have been studied for a wide range of applications in industry because they can be incorporated into the macroscopic matrix of several composites and also for point-of-use in drinking water filtration systems due to CNT high mass transfer capac- ity in fast flow rates at low pressures system (Pyrzynska 2011; Upadhyayula et al. 2009). Functionalized CNT are known for their capacity of removing metals from water (Rao et al. 2007; Sheng et al. 2010). One objective of this study was to evaluate the effectiveness of CNT for sorption/desorption cycles in comparison to granu- lated activated carbon (GAC) in packed column appli- cations. Nevertheless, the challenges to predict and Water Air Soil Pollut (2015) 226:215 DOI 10.1007/s11270-015-2482-7 Electronic supplementary material The online version of this article (doi:10.1007/s11270-015-2482-7) contains supplementary material, which is available to authorized users. S. Rosenzweig : G. A. Sorial (*) Department of Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, P.O. Box 210012, Cincinnati, OH 45221-0012, USA e-mail: George.Sorial@uc.edu T. Luxton NRMRL, Land Remediation and Pollution Control Division, Waste Management Branch, U.S. Environmental Protection Agency, 5995 Center Hill Ave., Cincinnati, OH 45224-170, USA E. Sahle-Demessie NRMRL, Office of Research and Development, U.S. Environmental Protection Agency, 26 W. Martin Luther King Drive (MS 443), Cincinnati, OH 45268, USA