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

Lei Xu; Xuebo Zheng; Hongbiao Cui; Zhenqiu Zhu; Jiani Liang; Jing Zhou

doi:10.1155/2017/3695604

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

Bioinorg Chem Appl. 2017:2017:3695604. doi: 10.1155/2017/3695604. Epub 2017 Feb 28.

Authors

Lei Xu¹, Xuebo Zheng¹, Hongbiao Cui², Zhenqiu Zhu¹, Jiani Liang³, Jing Zhou¹

Affiliations

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

Abstract

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.