ORIGINAL PAPER Adsorption of humic acid by amine-modified nanocellulose: an experimental and simulation study A. Jebali • A. Behzadi • I. Rezapor • T. Jasemizad • S. H. Hekmatimoghaddam • Gh. H. Halvani • N. Sedighi Received: 8 January 2014 / Revised: 9 June 2014 / Accepted: 9 August 2014 / Published online: 17 September 2014 Ó Islamic Azad University (IAU) 2014 Abstract The purpose of this study was to evaluate the adsorption of humic acid (HA) by amine-modified nano- cellulose. At first, nanocellulose was synthesized by acid hydrolysis, and then was modified by N-(2-aminoethyl)-3- aminopropylmethyldimethoxysilane. In the next step, HA and amine-modified nanocellulose were incubated at dif- ferent conditions (pH, incubation time, temperature, and concentration). Furthermore, we used molecular dynamic (MD) simulation for observation of adsorption at molecular scale. For this purpose, HA and amine-modified nanocellulose were prepared by HyperChem software (Hypercube, Inc., USA), and inserted in Ascalaph Designer 1.8.69 software. Once equilibrium was reached, interac- tions were simulated for 1,000 ps. Finally, different parameters such as interaction energy, potential energy, and root-mean-square displacement (RMSD) were mea- sured. This study demonstrated that the adsorption of HA was pH-, temperature-, dose-, and time-dependent. Based on simulation results, the interaction energy was reduced, but potential energy and RMSD were increased at the final stage of simulation, which indicated the adsorption of HA. The authors suggest amine-modified nanocellulose for removal of HA in wastewater. Keywords Humic acid  Adsorption  Amine-modified nanocellulose  Experimental  Simulation  Wastewater Introduction Various pollutants may exist in water, which decrease the quality of environmental water, and affect the health of human population and animals (Jonglertjunya and Ler- tchutimakul 2012). Among the environmental harmful pollutants, humic substances (HSs) are very important, which are formed by decomposition of plant and animal biomass. Regarding the chemical structure, they have a skeleton of aromatic units with different functional groups (e.g., carboxyl, phenolic, hydroxyl, and quinine). HSs are categorized into three compounds based on solubility, including humic acids (HAs), fulvic acids (FAs), and humans (Trump et al. 2006). HSs can cause different environmental and health problems including: (1) unde- sirable color and taste, (2) binding to heavy metals and biocides which yield new toxic materials, (3) reaction with A. Jebali (&) Department of Genetics, Research and Clinical Center for Infertility, Shahid Sadoughi University of Medical Sciences, Yazd, Iran e-mail: alijebal2011@gmail.com A. Behzadi  I. Rezapor Department of Food Hygiene and Safety, School of Health, Shahid Sadoughi University of Medical Science, Yazd, Iran T. Jasemizad Department of Environmental Health, Faculty of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran S. H. Hekmatimoghaddam Department of Laboratory Sciences, School of Paramedicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Gh. H. Halvani Department of Occupational Health, School of Public Health, Shaheed Sadoughi University of Medical Sciences, Yazd, Iran N. Sedighi Department of Food Science, College of Agriculture, Yazd Science and Research Branch, Islamic Azad University, Yazd, Iran 123 Int. J. Environ. Sci. Technol. (2015) 12:45–52 DOI 10.1007/s13762-014-0659-z