P. Peigneur, A. Maes and A. Cremers, “Heterogeneity of Charge Density Distribution in Montmorillonite as Inferred from Cobalt Adsorption,” Clays and Clay minerals, Vol. 23, 1975, pp. 71-75. doi:10.1346/CCMN.1975.0230110
 M. F. Brigatti, F. Corradini, et al., “Interaction between Montmorillonite and Pollutants from Industrial Waste- Water: Exchange of Zn2+ and Pb2+from Aqueous Solutions,” Applied Clay Science, Vol. 9, 1995, pp. 383-385. doi:10.1016/0169-1317(94)00027-N
 M. J. Garcia and A. L. Page, “Influence of Ionic Strength and in Organic Complex Formation on the Sorption of Trace Amounts of Cd by Montmorillonite,” Soil Science Society of America Proceedings, Vol. 40, 1976, pp. 658-663.
 H. Omar, H. Arida and A. Daifullan, “Adsorption of 60Co Ra-dionuclides from Aqueous Solution by Raw and Modified Bentonite,” Applied Clay Science, Vol. 44, 2009, pp 21-26. doi:10.1016/j.clay.2008.12.013
 S. T. Akar, T. Akar and Z. Kaynak, “Removal of Copper (ii) Ions from Synthetic Solution and Real Wastewater by the Combined Action of Dried Tram-etes Versicolor Cells and Montmorillonite,” Hydrometallurgy, Vol. 97, 2009, pp. 98-104. doi:10.1016/j.hydromet.2009.01.009
 E. Alvarez-Ayuso and A. Ganchez-Sanchez, “Removal of Heavy Metals from Waste Waters by Natural and Na-exchanged bentonite.” Clays and Clay Minerals, Vol. 51, No. 5, 2003, pp. 475-480. doi:10.1346/CCMN.2003.0510501
 W. Matthes, F. T. Madsen and G. Kahr, “Sorption of Heavy-Metal Cations by Al and Zr-hydroxy Intercalated and Pillared Bentonite,” Clays and Clay Minerals, Vol. 47, No. 5, 1999, pp. 617-629. doi:10.1346/CCMN.1999.0470508
 G. Bayramoglu and M. Y. Arica, “Construction a Hybrid Biosorbent Using Scenedes-mus Quadricauda and Ca-Alginate for Biosorption of Cu (II), Zn (II) and Ni (II): Kinetics and Equilibrium Studies,” Biore-source Technology, Vol. 100, 2009, pp. 186-193. doi:10.1016/j.biortech.2008.05.050
 Ministry of Environ-mental Protection of the People’s Republic of China, Commit-tee on Water and Wastewater Monitoring Methods, “Monitor-ing Analysis Method of Water and Wastewater,” Environ-mental Science Press of China, Beijing, 2002.
 M. Alkan, B. Kalay, M. Do?an and ?. Demirba?, “Removal of Copper Ions from Aqueous Solutions by Kaolinite and Batch Design,” Journal of Hazardous Materials, Vol. 153, 2008, pp. 867-876. doi:10.1016/j.jhazmat.2007.09.047
 E. I. Unuabonah, B. I. Olu-Owolabi, K. O. Adebowale, et al. “Adsorption of Lead and Cadmium Ions from Aqueous Solutions by Tripolyphosphate-Impregnated Kaolinite Clay,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007, Vol. 292, pp. 202-211. doi:10.1016/j.colsurfa.2006.06.024
 S. L. Ding, Y. Z. Sun, C. N. Yang and B. h. Xu, “Removal of Copper from Aqueous Solutions by Ben-tonites and the Factors Affecting it,” Mining Science and Tech-nology, 2009, Vol. 19, No. 4, pp. 489-492. doi:10.1016/S1674-5264(09)60091-0