Journal of Ecology and Rural Environment ›› 2021, Vol. 37 ›› Issue (1): 73-79.doi: 10.19741/j.issn.1673-4831.2020.0071

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Adsorption of Cd2+ from Aqueous Solution by Modified Rice Husk-derived Biochars

REN Jie-qing1,2, WANG Chao-xu1,2, ZHANG Feng1,2, LI Hong-yan1,2, CUI Jian-guo1,2   

  1. 1. College of Environmental Science and Engineering, Taiyuan University of Technology, Jinzhong 030600, China;
    2. Innovation Center for Postgraduate Education in Municipal Engineering of Shanxi Province, Jinzhong 030600, China
  • Received:2020-02-06 Published:2021-01-22

Abstract: To improve Cd2+ adsorption ability of biochar in aqueous solution, NaOH- and FeCl3-modified biochars (NBC1, NBC2 and FBC1, FBC2) were prepared based on two kinds of original rice husk-derived biochars (BC1, BC2). Moreover, Cd2+ adsorption performances of the six materials were explored by the kinetics and isothermal adsorption experiments. Results show that Cd2+ equilibrium adsorption capacities of BC1 and BC2 were 14.76 and 13.72 mg·g-1 under the condition of Cd2+ concentration 50 mg·L-1 and biochar dosage 1 g·L-1, respectively. NaOH-modification enhanced the Cd2+ adsorption ability of rice husk-derived biochars consistently and significantly, and the equilibrium adsorption capacities of NBC1 and NBC2 were 3.26 and 2.47 times that of BC1 and BC2, respectively. However, FeCl3-modification had little effect on Cd2+ adsorption of the biochars, and the equilibrium adsorption capacities of FBC1 and FBC2 were only 1.03 and 0.74 times that of BC1 and BC2. The process of Cd2+ adsorption onto the original and modified rice husk-derived biochars was more consistent with the pseudo-second-order model and the Langmuir model, and it was assumed that the adsorption mainly occurs in monolayers. The maximum adsorption capacities of NBC1 and NBC2 (131.58 and 98.04 mg·g-1, respectively) were significantly higher than that of FBC1 and FBC2 (30.30 and 23.26 mg·g-1, respectively). The reason for Cd2+ adsorption capacity enhancement of NaOH-modified biochars is that NaOH-modification increased the amount of alkaline oxygen-containing functional groups on the surface of biochars, which enhances biochars' cation exchange and precipitation capacity with Cd2+.

Key words: rice husk-derived biochar, modification, Cd2+, adsorption

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