ORIGINAL RESEARCH
Removal of Cd(II) from Aqueous Solutions
by Aluminium Hydroxide-Modified Attapulgite
| 1 | College of Resources and Environment, Gansu Agricultural University, Lanzhou, China |
CORRESPONDING AUTHOR
Liqun Cai
College of Resources and Environment, Gansu Agricultural University, 730070, Lanzhou, China
College of Resources and Environment, Gansu Agricultural University, 730070, Lanzhou, China
Submission date: 2020-07-27
Final revision date: 2020-10-01
Acceptance date: 2020-11-02
Online publication date: 2021-02-22
Publication date: 2021-04-16
Pol. J. Environ. Stud. 2021;30(3):2905–2915
KEYWORDS
TOPICS
ABSTRACT
Modified attapulgite (ATP-Al) was prepared with aluminium hydroxide through a co-precipitation
method, and we used ATP-Al as an adsorbent to investigate the adsorption of Cd(II) from aqueous
solutions. Raw ATP and ATP-Al were characterized by TEM, FTIR, XRD and Zeta. Adsorption
parameters, such as pH, initial Cd(II) concentration, contact time and adsorbent dose, were evaluated
to explain the mechanism of Cd(II) adsorption on ATP-Al. ATP-Al had a better adsorption capacity
of Cd(II) than ATP. When the pH value was 7, ATP and ATP-Al had the highest Cd(II) adsorption
capacities. The optimal dose of adsorbent was 0.1 g per 25 mL of solution. The Freundlich model better
described the adsorption isotherm on ATP and ATP-Al than the Langmuir model. The maximum
adsorption capacity for Cd(II) calculated was 4.01 and 6.36 mg g-1, respectively. Adsorption of Cd(II)
onto ATP and ATP-Al followed pseudo-second order kinetics. The Gibbs free energy (ΔG°), enthalpy
(ΔH°) and entropy (ΔS°) were evaluated by a thermodynamic study. The adsorption processes of ATP
and ATP-Al were exothermic, spontaneous and mainly based on physical adsorption.
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