Chinese Journal of Applied Chemistry ›› 2023, Vol. 40 ›› Issue (2): 288-298.DOI: 10.19894/j.issn.1000-0518.220169

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Adsorption Performance of Rhodamine B on Magnetic Biochar Prepared at Different Pyrolysis Temperatures

Qian YANG, Yang ZHANG, Ming-Yang LAI, Lin GUO, Jian-Bo JIA()   

  1. School of Biotechnology and Health Sciences,Wuyi University,Jiangmen 529000,China
  • Received:2022-05-06 Accepted:2022-11-06 Published:2023-02-01 Online:2023-02-27
  • Contact: Jian-Bo JIA
  • About
  • Supported by:
    the National Natural Science Foundation of China(21974097);the Education Department of Guangdong Province(2020KSYS004)


Using rice straw as the raw material, an one-step magnetization carbonization method is used for oxygen-limited pyrolysis at 550, 600, 650 and 700 ℃ to prepare high-efficient and easy-separable magnetic biochar (MBC). The physicochemical properties of MBC are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Emmett and Teller analysis (BET) and Fourier transform infrared spectrometer (FT-IR), and the effects of different temperatures on their structural properties and adsorption performances are investigated. The effects of metal cations (Na+, Fe3+, Mg2+, Cu2+) and pH on the adsorption performance are also investigated. The results show that the specific surface area and pore volume of MBC increase with the increase of pyrolysis temperature, and the adsorption ability or capacity of MBC is significantly affected by temperature. The equilibrium adsorption capacities of the four different pyrolysis temperatures are 35.696, 36.962, 53.118 and 54.810 mg/g for Rhodamine B(RhB), respectively. The adsorption of RhB by the four kinds of MBC was in accordance with the pseudo second order kinetic equation, indicating that the adsorption of RhB by MBC was affected by many factors. Langmuir and Freundlich equations were used to fit the isotherm adsorption results, and the adsorption isotherms were in line with Freundlich model, indicating that the adsorption of RhB by MBC was dominated by the physical adsorption of multi molecular layers. The adsorption capacity of MBC on RhB increases and then decreases with the increase of pH due to electrostatic adsorption and ion exchange, and reaches the maximum capacity at pH 6. After the addition of Na+, Fe3+, Cu2+, Mg2+ metal cations, the adsorption capacities of the four kinds of MBC for RhB are all lower than the equilibrium adsorption capacities. The increase of Na+ and Fe3+ ion concentrations has a certain upward trend on the adsorption capacity of some MBC for RhB. However, the increase of Cu2+ and Mg2+ ion concentrations has little effect on the adsorption of RhB by MBC.

Key words: Rice straw, Pyrolysis temperature, Magnetic biochar, Rhodamine B, Metal cation

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