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Chinese Journal of Applied Ecology ›› 2018, Vol. 29 ›› Issue (4): 1328-1338.doi: 10.13287/j.1001-9332.201804.034

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Cadmium adsorption by biochar prepared from pyrolysis of silk waste at different temperatures

JI Hai-yang1,2, WANG Yu-ying2,3 , LYU Hao-hao2,3, LIU Yu-xue2,3, YANG Rui-qin4,5, YANG Sheng-mao1,2,3*   

  1. 1College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, Zhejiang, China;
    2Institute of Environment, Resource, Soil and Fertilizer, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China;
    3Engineering Research Center of Biochar of Zhejiang Province, Hangzhou 310021, China;
    4Zhejiang Provincial Collaborative Innovation Center of Agricultural Biological Resources Biochemical Manufacturing, Hangzhou 310023, China;
    5Zhejiang Provincial Key Laboratory for Chem&Bio Processing Technology of Farm Product, Hangzhou 310023, China;
  • Received:2017-07-24 Online:2018-04-18 Published:2018-04-18
  • Contact: * E-mail: yangshengmao@263.net
  • Supported by:

    This work was supported by the Natural Science Foundation of Zhejiang(LQ17D020002, LY16D010004) and the Zhejiang Provincial CollaborativeInnovation Center of Agricultural Biological Resources Biochemical Manufacturing/Zhejiang Provincial Key Labarotory for Chem&Bio Processing Technology of Farm Product open fund (2016KF0116).

Abstract: In this study, biochars (BC300, BC500 and BC700) were produced from silk waste through pyrolysis under oxygen-limited condition at 300, 500 and 700 ℃, respectively. The physicochemical properties of biochar were detected by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD) and specific surface area analyzer. The Cd2+ adsorption capacities of biochars were investigated. Results showed that BET surface area, pH, and ash were increased with the increases of pyrolysis temperature. SEM images showed that the surfaces of biochars were rough and irregular. XRD and FT-IR results showed that all the silk waste biochars obtained at different temperatures contained calcite. pH had limited influence on the removal efficiency of biochar for Cd2+. Langmuir isotherm fitted the experimental data quite well. The Langmuir monolayer adsorption capacity of BC300, BC500, and BC700 were 25.61, 52.41, and 91.07 mg·g-1, respectively. The adsorption of Cd2+ onto the biochars obeyed a pseudo second-order kinetic model, with the BC700 showing the best removal efficiency. Further-more, the effects of the ionic strength and coexisting cations on Cd2+ removal were investigated. The results showed that the removal of Cd2+ was decreased with the increases of NaCl. Among the coexisting cations, the removal of Cd2+ was decreased by Ca2+ and Mg2+, while K+ had limited effect on the removal of Cd2+. In conclusion, the biochar derived from silk waste pyrolysis is a potential attractive adsorbent for the removal of Cd2+ from water.

Key words: biochar, silk waste, adsorption., pyrolysis temperature, Cd2+