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Bioinorganic Chemistry and Applications
Volume 2017, Article ID 3695604, 9 pages
Research Article

Equilibrium, Kinetic, and Thermodynamic Studies on the Adsorption of Cadmium from Aqueous Solution by Modified Biomass Ash

Lei Xu,1,2,3,4 Xuebo Zheng,1,2,3,4 Hongbiao Cui,5 Zhenqiu Zhu,1,2,3,4 Jiani Liang,1,2,3 and Jing Zhou1,2,3,4

1Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
2Key Laboratory of Soil Environment and Pollution Remediation, Chinese Academy of Science, Nanjing 210008, China
3National Engineering and Technology Research Center for Red Soil Improvement, Red Soil Ecological Experiment Station, Chinese Academy of Sciences, Liujiazhan Plantation, Yingtan 335211, China
4University of Chinese Academy of Sciences, Beijing 100049, China
5School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China

Correspondence should be addressed to Jing Zhou;

Received 27 September 2016; Revised 19 December 2016; Accepted 22 January 2017; Published 28 February 2017

Academic Editor: Guillermo Mendoza-Diaz

Copyright © 2017 Lei Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Natural biomass ash of agricultural residuals was collected from a power plant and modified with hexagonal mesoporous silica and functionalized with 3-aminopropyltriethoxysilane. The physicochemical and morphological properties of the biomass ash were analyzed by ICP-OES, SEM, TEM-EDS, FTIR, and BET analysis. The adsorption behavior of the modified product for Cd2+ in aqueous solution was studied as a function of pH, initial metal concentration, equilibrium time, and temperature. Results showed that the specific surface area of the modified product was 9 times that of the natural biomass ash. The modified biomass ash exhibited high affinity for Cd2+ and its adsorption capacity increased sharply with increasing pH from 4.0 to 6.0. The maximum adsorption capacity was 23.95 mg/g in a pH 5 solution with an initial metal concentration of 50 mg/L and a contact time of 90 min. The adsorption of Cd2+ onto the modified biomass ash was well fitted to the Langmuir model and it followed pseudo-second-order kinetics. Thermodynamic analysis results showed that the adsorption of Cd2+ was spontaneous and endothermic in nature. The results suggest that the modified biomass ash is promising for use as an inexpensive and effective adsorbent for Cd2+ removal from aqueous solution.