References
  -  X. Tao, H. Yang, R. Ji, A.M. Li, Stabilizers and their applications
    in remediation of heavy metal-contaminated soil, Soils,
    48 (2016) 1–11. 
 
  -  M.F. Chen, Review on heavy metal remediation technology
    of soil and groundwater at industrially contaminated site in
    China, Bull. Chin. Acad. Sci., 29 (2014) 327–335. 
 
  -  T. Fan, W.L. Ye, H.Y. Chen, H.J. Lu, Y.H. Zhang, D.X. Li,
    Z.Y. Tang, Y.H. Ma, Review on contamination and remediation
    technology of heavy metal in agricultural soil, Ecol. Environ.
    Sci., 22 (2013) 1727–1736. 
 
  -  X.L. Liu, R. Ma, X.X. Wang, Y. Ma, Y.P. Yang, L. Zhuang,
    S. Zhang, R. Jehen, J.R. Chen, X.K. Wang, Graphene oxide
    based materials for efficient removal of heavy metal ions from
    aqueous solution: a review, Environ. Pollut., 252 (2019) 62–73. 
 
  -  W.Q. Du, W. Cao, H. Zhou, W.T. Yang, J.F. Gu, P.Q. Peng,
    P. Zhang, B.H. Liao, Optimization and the mechanism in
    treatment of heavy metals wastewater with magnetic biochar,
    Acta Sci. Circumstantiae, 38 (2018) 492–500. 
 
  -  S. Bai, Agricultural and forestry wastes material as potential
    adsorbent for heavy metal ions from aqueous solutions:
    a review, Environ. Sci. Technol., 37 (2014) 94–98. 
 
  -  S.F. Lim, A.Y.W. Lee, Kinetic study on removal of heavy metal
    ions from aqueous solution by using soil, Environ. Sci. Pollut.
    Res., 22 (2015) 10144–10158. 
 
  -  Z.B. Huang, P.C. Sun, J. Zhong, Y. Chen, Application of super
    absorbent polymer in water and fertilizer conversation of soil
    and pollution management, Trans. Chin. Soc. Agric. Eng.,
    32 (2016) 125–131. 
 
  -  Q. Ma, X.L. Zhang, Advances in new technology for heavy
    metal wastewater treatment at home and abroad, Chin. Environ.
    Eng., 1 (2007) 10–14. 
 
  -  S.D. Shen, J. Xu. Adsorption of Cu(II) and Zn(II) ions onto
    NaOH-modified grapefruit husk powder, Environ. Sci.
    Technol., 33 (2010) 115–119. 
 
  -  J.X. Yi, Z.P. Huo, M.A. Asiri, K.A. Alamry, J.X. Li, Application
    of agroforestry waste biomass adsorption materials in water
    pollution treatment, Prog. Chem., 31 (2019) 760–772. 
 
  -  R. Yu, X. Hu, Z.H. Ding, Y.F. Zhang, D.Q. Yin, Adsorption
    of Cr3+, Cu2+ and Ni2+ using peanut hull, soybean shell and
  grapefruit peel, Environ. Pollut. Control, 35 (2013) 43–53. 
 
  -  Y.Y. Huang, Research progress of wastewater treatment by
    agricultural wastes as biological adsorbent, Appl. Chem. Ind.,
    46 (2017) 368–372. 
 
  -  S. Liang, N.C. Feng, X.Y. Guo, Progress of heavy metal
    wastewater treatment by biosorption, Water Treat. Technol.,
    35 (2009) 13–17. 
 
  -  Y.L. Wen, P. Liu, Q. Tang, Review of removal of heavy metal
    ions from wastewater with agricultural and forestry waste as
    adsorbent, Chem. Ind. Prog., 35 (2016) 1208–1215. 
 
  -  Y.L. Mao, H.Y. Kang, J.F. Wu. Adsorption performances of Cd(II)
    from water by oxalic acid modified pomelo peel, J. Environ.
    Eng., 10 (2016) 65–72. 
 
  -  J.X. Yu, R.A. Chi, Y.L. Xu, Y.F. Zhang, Preparation of modified
    sugarcane bagasse and its comprehensive chemical experiment
    of adsorption performance toward heavy metal ions, Exp.
    Technol. Manage., 32 (2015) 39–42. 
 
  -  J.R. Memon, K.R. Hallam, M.I. Bhanger, A. EI-Turki, G.C. Allen,
    Evaluation of sorption of uranium onto metakaolin using X-ray
    photoelectron and Raman spectroscopies, Anal. Chim. Acta,
    631 (2009) 69–73. 
 
  -  M. Ajmal, R.A.K. Rao, R. Ahmad, J. Ahmad, Adsorption studies
    on Citrus reticulata (fruit peel of orange): removal and recovery
    of Ni(II) from electroplating wastewater, J. Hazard. Mater.,
    79 (2000) 117–131. 
 
  -  L.G. Wang, J.K. Zhong, B.W. Zhao, J.Y. Zhang, L. Li, Q.Z. Yang,
    W.Y. Chen, Adsorption and interaction of Cd(II) and pyrene in
    water on walnut shell biochar, J. Agro-Environ. Sci., 36 (2017)
    1868–1876. 
 
  -  K.J. Osvaldo, V.A.G. Leandro, R.P.D. Freitas, L.F. Gil, Adsorption
    of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions
    by mercerized cellulose and mercerized sugarcane bagasse
    chemically modified with EDTA dianhydride (EDTAD),
    Carbohydr. Polym., 77 (2009) 643–650. 
 
  -  X.B. Sun, W.J. Zhou, H.Y. Zhai, Study on adsorption of dyes on
    modified lemon peel, New Chem. Mater., 43 (2015) 176–180. 
 
  -  J.Y. Liu, G.H. Huang, J.Q. Deng, K. Liu, Y.B. Xie, Adsorbent
    prepared from waste pomelo peel and its adsorption of Pb2+
    in wastewater, J. Ecol. Rural Environ., 28 (2012) 187–191. 
 
  -  Z.M. He, Q. Wang, H.Y. Fu, L. Zeng, Z.H. Xie, Adsorption
    removal of Cr(VI)/As in aqueous solution by pomelo peel,
    Environ. Eng., 34 (2016) 299–302. 
 
  -  X.L. Li, H.Y. Deng, W.B. Li, T. Li, D. Wang, Study on enhanced
    adsorption of Cu2+ on purple soil by BS-12 amphoteric
    modified materials, Desal. Water Treat., 196 (2020) 150–158. 
 
  -  S.P. Feng, L. Liang, Y. Zhu, X.D. Zou, X.D. Zhang, Speciation
    analysis of the river sediment(II) – Tessier sequential chemical
    extraction procedures, J. Shandong Univ., 39 (2004) 101–104. 
 
  -  J. Xie, H.Y. Deng, L. Zhu, Y.F. Zhang, W.B. Li, D. Wang,
    Z.F. Meng, Preparation of amphoteric modified magnetized
    carbon and its adsorption to Cu(II), Desal. Water Treat.,
    194 (2020) 180–186. 
 
  -  W.B. Li, L. Zhu, H.Y. Deng, Y.F. Zhang, J. Xie, X.Y. Chen, T. Li,
    Z.F. Meng, Effect of biochar application on adsorption of copper
    by riverbank soils, Earth Environ., 48 (2020) 250–257. 
 
  -  E.F. Covelo, F.A. Vega, M.L. Andrade, Competitive sorption
    and desorption of heavy metals by individual soil components,
    J. Hazard. Mater., 140 (2007) 308–315. 
 
  -  X.Q. Chang, M. Zhou, Q. Shen, Removal of arsenic in drinking
    water by modified maifanite adsorption, Water Purif. Technol.,
    32 (2013) 19–22. 
 
  -  W.B. Li, Z. Liu, Z.F. Meng, S. Ren, S.E. Xu, Y. Zhang, M.Y.
    Wang, Composite modification mechanism of cationic modifier
    to amphoteric modified kaolin and its effects on surface
  characteristics, Int. J. Environ. Sci. Technol., 13 (2016) 2639–2648.