Journal of Ecology and Rural Environment ›› 2016, Vol. 32 ›› Issue (6): 986-991.doi: 10.11934/j.issn.1673-4831.2016.06.018

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Effects of Attapulgite and Sepiolite Adsorbing Cadmium in Aqueous Solution

WANG Jian1,2,3, LI Ren-yin1, HE Yue2,3, WU Yun-jin2,3, JIAO Shao-jun2, ZHAO Li4   

  1. 1. College of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China;
    2. Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China;
    3. State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing 210042, China;
    4. Jiangsu Yongwei Foreverway Environment Construction Co. Ltd., Nanjing 210000, China
  • Online:2016-11-25 Published:2016-11-30

Abstract:

Effects of attapulgite and sepiolite adsorbing Cd2+ in aqueous solutions relative to initial concentration, solid-liquid ratio, exposure duration, and pH were investigated through a static batch experiment under a set NaNO3 ionic strength (0.01 mol·L-1). Results show that, under the set NaNO3 ionic strength, Cd2+ adsorption of sepiolite and attapulgite of high grade and attapulgite of low grade is positively related to initial concentration of Cd2+ in the solution, but negatively to solid-liquid ratio of the solution. Fitting with the Langmuir isothermal adsorption equation reveals an order of high grade attapulgite (33.67 mg·g-1) >high grade sepiolite (25.55 mg·g-1) >low grade attapulgite(11.52 mg·g-1) >low grade sepiolite (5.24 mg·g-1) in terms of theoretical saturated Cd2+adsorption; Cd2+ adsorption on sepiolite and attapulgite is strongly influenced by pH of the solution, and peaks when pH is 2-4; Cd2+ adsorption on attapulgite is relatively stable and reaches equilibrium basically in 3 h; in solutions 0.01 mol·L-1 NaNO3 in ionic strength, 625 mg·L-1 in initial Cd2+ concentration, 15 g·L-1 in clay mineral addition amount and 2-4 in pH, the minerals display an order of high grade sepiolite >high grade attapulgite >low grade attapulgite >low grade sepiolite in terms of Cd removal efficiency.

Key words: sepiolite, attapulgite, adsorption, cadmium

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