PROMOTING ACCESS TO AFRICAN RESEARCH

Bulletin of the Chemical Society of Ethiopia

Log in or Register to get access to full text downloads.

Remember me or Register



Thermodynamic studies on the adsorption of Cu2+, Ni2+ and Cd2+ on to amine-modified bentonite

X. Zhu, L. Lan, N. Xiang, W. Liu, Q. Zhao, H. Li

Abstract


Amine-modified bentonite (TEPA-Bn) has been prepared with tetraethylenepentamine (TEPA) as a modifier. The structure of Ca-based bentonite (Ca-Bn), TEPA-Bn and TEPA-Bn after adsorbing Cu2+,Ni2+,Cd2+ had been characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and simultaneous thermal gravimetric/differential thermal gravimetric (TG/DTG) analysis. The TEPA had been intercalated into Ca-Bn interlayer space but had not changed its original crystal structure. The thermal stability of TEPA-Bn was stronger than Ca-Bn while the hydrophilicity of it reduced. The adsorption ability of TEPA-Bn to Cd2+, Ni2+, Cu2+ was much better than Ca-Bn, the saturated adsorption capacity to Cd2+, Ni2+, Cu2+ were 14.88, 8.88 and 13.05 times as much as Ca-Bn, respectively. The adsorption behavior of Cu2+, Ni2+, Cd2+ on to TEPA-Bn were studied by isothermal models, including Freundlich, Langmuir, Dubinin-Radushkevich Florry-Huggins, and Tempkin models. The Freundlich model simulated the experimental data best, the adsorption of Cu2+, Ni2+, Cd2+ onto TEPA-Bn was a multilayer, heterogeneous chemical process. The variety of thermodynamic parameters (DH > 0, DS > 0, DG < 0) under different temperature indicated that the adsorption process of Cu2+, Ni2+, Cd2+ on TEPA-Bn was endothermic and spontaneous.

 

KEY WORDS: Amine-modified bentonite, TEPA, Heavy metal ions, Adsorption thermodynamics, Characterization

 

Bull. Chem. Soc. Ethiop. 2016, 30(3), 357-367

DOI: http://dx.doi.org/10.4314/bcse.v30i3.4




http://dx.doi.org/10.4314/bcse.v30i3.4
AJOL African Journals Online