Adsorption Kinetics and Isotherms of Cr(VI) Ions in Aqueous Solution by Biochar Derived from Torreya grandis Nutshell
2019
Chengcai Huang, Rui Qin, Linli Zhang, Muqing Qiu and Linfa Bao
Biochar is thought to be a good adsorption material for the adsorption of heavy metals. In this study, biochar derived from Torreya grandis nutshell was prepared through to be pyrolyzed under oxygen limited conditions in a muffle furnace. The adsorption experiments of Cr(VI) were carried out. Through Elemental Analyzer, Specific Surface Area Meter, Scanning Electron Microscopy, Transmission Electron Microscopy and Fourier Transform Infrared Spectroscopy, a fundamental understanding of the physical and chemical properties of biochar was gained. The results showed that it was a smooth sheet and irregular arrangement structure. The elements of C, H, O and N of biochar are 45.21%, 5.18%, 46.16% and 3.45% respectively. BET specific surface area of biochar is 42.24 m2/g. A lot of oxygencontaining functional groups (– OH, COO –, – C – OH and so on ) appeared on the surface of biochar. It can be described by the pseudo-second order kinetic rate model and Langmuir isotherm model. The adsorption process is a monolayer chemical process. The adsorption mechanism of biochar on heavy metal Cr(VI) contains the electrostatic attraction between biochar and Cr2O7 2-, HCrO4 - and CrO4 2- ions in aqueous solution and complexation reaction of oxygen-containing functional groups (– OH, – COOH and so on) and Cr2O7 2- , HCrO4 - and CrO4 2- ions on the surface of biochar.
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