Surface modification of malonic acid‐catalyzed carbon xerogels and their high performance for adsorption of Cu (II) ions

Abstract

The preparation of malonic acid‐catalyzed carbon xerogels modified with nitric acid and their high performance for adsorption of Cu2+ were investigated. The treated and untreated carbon xerogels (nitrogen‐doped carbon xerogel and carbon xerogel) are mainly microporous with high surface areas (1150.18 and 1201.46 m2 g−1) based on the analysis of N2 adsorption isotherm. Fourier transform infrared spectroscopy study demonstrates that modification process generates a number of functional groups such as carboxyl, carbonyl, and nitrate groups. X‐ray photoelectron spectra analysis shows an increase in the content of O and N after oxidation. The adsorption performance for Cu2+ using different process parameters like initial concentration, contact time, and temperature was investigated. The result indicates that the pseudo‐second order correlates with the experimental data, and the activation energy of Cu2+ adsorption onto nitrogen‐doped carbon xerogel and carbon xerogel is calculated as 15.62 kJ mol−1 and 2.79 kJ mol−1, respectively, indicating the coexistence of chemisorption and ion‐exchange. Langmuir and Freundlich isotherms were used to describe the adsorption behavior of Cu2+. The adsorption of Cu2+ by carbon xerogels modified with nitric acid was fast and had noticeable adsorption capacity, with a higher adsorption capacity than the original carbon xerogels (299.41 vs 260.42 mg g−1). Copyright © 2013 John Wiley & Sons, Ltd.