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.

Spectroscopic investigation of nitrogen‐functionalized carbon materials

“…For XPS, structures that have nitrogen substituted for carbon (graphitic nitrogen) are typically reported between 399.8 eV and 401.8 eV . In Fig.…”

Resorcinol-Formaldehyde Carbon Gels Adsorption: A Commentary

“…provides the driving force to overcome the resistance of mass transfer at adsorbent phase, from which the adsorption increases with increasing concentration. [21][22] Likewise, a longer time would be needed to achieve the equilibrium as the concentration increases. [21][22] The post-treatment using HNO 3 increases the mesoporosity of carbon gel at the expense of slight decrease in surface area.…”

“…[21][22] Likewise, a longer time would be needed to achieve the equilibrium as the concentration increases. [21][22] The post-treatment using HNO 3 increases the mesoporosity of carbon gel at the expense of slight decrease in surface area. 18,21,23 Xiao and co-workers 21 Table 2.…”

“…[21][22] The post-treatment using HNO 3 increases the mesoporosity of carbon gel at the expense of slight decrease in surface area. 18,21,23 Xiao and co-workers 21 Table 2. Adsorption properties of carbon gels.…”

“…The rate constant generally decreases with increasing concentration because of the intensified collision of dye molecules. 21 On the other hand, a greater rate constant with increasing concentration is attributed to a stronger driving force to overcome mass transfer resistance. 22 According to Arrhenius theory, a weak activation energy endows a high rate constant that is associated with a rapid adsorption due to less repulsion of molecules and mutual interactions between the adsorbate and adsorbent surface characteristics.…”