Clay–iron oxide magnetic composites for the adsorptionof contaminants in water

LUIZ C.A. OLIVEIRA, RACHEL V.R.A. RIOS, JOSE´ D. FABRIS, KARIM SAPAG, VIJAYENDRA K. GARG, ROCHEL M. LAGO

APPLIED CLAY SCIENCE

Elsevier

Lugar: Amsterdam; Año: 2003 vol. 22 p. 169 - 177

0169-1317

In this work, the adsorption features of clays with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. These magnetic composites can be used as adsorbent for contaminants in water and can be subsequently removed from the medium by a simple magnetic process. The bentonite–iron oxide magnetic composites have been prepared with weight ratios of 2:1, 1.5:1, and 1:1 and characterized by powder X-ray diffraction (XRD), thermogravimetric analysis (TG), magnetization measurements, chemical analyses, temperature-programmed reduction (TPR), N2 adsorption–desorption isotherms, Mo¨ssbauer spectroscopy, and scanning electron microscopy (SEM). The results suggest that the main magnetic phase present is maghemite (g-Fe2O3). A magnetization enhancement can be produced by treatment with H2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. treatment with H2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. suggest that the main magnetic phase present is maghemite (g-Fe2O3). A magnetization enhancement can be produced by treatment with H2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. treatment with H2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. 2 adsorption–desorption isotherms, Mo¨ssbauer spectroscopy, and scanning electron microscopy (SEM). The results suggest that the main magnetic phase present is maghemite (g-Fe2O3). A magnetization enhancement can be produced by treatment with H2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. treatment with H2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. g-Fe2O3). A magnetization enhancement can be produced by treatment with H2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. 2 at 600 jC to reduce maghemite to magnetite. Nitrogen adsorption isotherms showed that the surface area and microporosity increased from 7 m2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. 2 g 1 (Vmicropores = 0.003 cm3 g 1) for the pure bentonite to 55 m2 g 1 (Vmicropores = 0.009 cm3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite. 3 g 1) for the composite clay/iron oxide (2:1). The adsorption isotherms of metal ions Ni2 +, Cu2 +, Cd2 +, and Zn2 + from aqueous solution onto the composites also showed that the presence of iron oxide produced an increase on the adsorption capacity of the bentonite.