@Article{jrm.2020.09369,
AUTHOR = {Li Fu, Xianying Xu, Guiquan Fu, Renduo Zhang, Hujun Liu},
TITLE = {Adsorption and Desorption Characteristics of Cadmium Ion by Ash-Free Biochars},
JOURNAL = {Journal of Renewable Materials},
VOLUME = {8},
YEAR = {2020},
NUMBER = {7},
PAGES = {801--818},
URL = {http://www.techscience.com/jrm/v8n7/39322},
ISSN = {2164-6341},
ABSTRACT = {The aim of this study was to investigate adsorption and desorption characteristics of cadmium ion (Cd(II)) by ash-free biochars and the adsorption
mechanism. Biochars were prepared using peanut shell, bamboo, and Sophora
japonica Linn. Ash-free biochars were obtained by treating the biochars with acid
elution. Adsorption and desorption data from batch experiments were analyzed
using the Langmuir and Freundlich models and three adsorption kinetics models
(i.e., the Pseudo second-order, Elovich model, and the Intraparticle diffusion models). Results showed that the acid elution improved the pore structure of biochars,
increased C content and aromatic functional group content, enhanced biochars
hydrophobicity and adsorption capacity for Cd(II). Ash-free peanut shell biochar
showed the best Cd(II) adsorption performance among the biochars. Adsorption
of ash-free peanut shell biochar reached the equilibrium within 6 h with adsorption capacity of 34.2 mg/g. The adsorption conditions were optimized by orthogonal experiment. The Cd(II) removal efficiency achieved 91.7% with the
optimized condition: initial concentration of Cd(II) of 50 mg/L, pH of 5, adsorption time of 12 h, and temperature of 15°C. Isothermal adsorption of Cd(II) by the
six biochars was best described with the Langmuir model, indicating that the
adsorption was a physical-chemical composite process. The desorption isotherm
showed the hysteresis between adsorption and desorption. The main mechanism
of Cd(II) adsorption of the ash-free biochars was a complex interaction of physical and chemical reactions, mainly including electrostatic adsorption, cationic-π,
and ligand exchange.},
DOI = {10.32604/jrm.2020.09369}
}