Abstract
The adsorption properties of coexistent Cr(VI) and Cu(II) in mixed solution on magnetic magnetite (Fe3O4) nanoparticle were studied in batch experiments. The influences of various factors, such as pH, adsorbent dose, temperature, initial concentration of metal ions, and coexisting ions in water were investigated. At the same time, the adsorption kinetics and adsorption isotherms were studied. The mechanism of adsorption for Cr(VI) and Cu(II) was investigated through the study of surface properties of Fe3O4, the presence of ions, and the influence of pH and zeta potential. The results indicate that pH has an influence on adsorption for Cr(VI) and Cu(II), and the optimal pH value for Cr(VI) and Cu(II) adsorption is 4.0. The adsorption efficiency increased with the increase of the adsorbent dose. Temperature under experimental design had no obvious effect. With 2.0 g/dm3 Fe3O4, the maximum adsorption capacity for Cr(VI) and Cu(II) reached 8.67 mg/g and 18.61 mg/g in mixed solution of 80 mg/dm3 Cr(VI) and Cu(II), respectively. Phosphorus had some influence on the adsorption for Cr(VI), and other coexisting anions and cations had no influence on the adsorption for Cr(VI) and Cu(II). The adsorption data for Cr(VI) and Cu(II) were nicely fit to the Langmuir adsorption equation and the pseudo-second-order model. As a multifunctional material, nano-Fe3O4 exhibited good adsorption performance for coexistent Cr(VI) and Cu(II) and could easily be separated and recovered under magnetic field.
Highlights
In recent years, water pollution of heavy metals has become a serious problem
The effect of pH on the adsorption of Cr(VI) and Cu(II) on Fe3 O4 was evaluated at pH values
This indicates that the adsorption process was well accordant with the pseudo-second-order reaction [32]
Summary
Water pollution of heavy metals has become a serious problem. Some metals have high toxicity and a tendency to accumulate and transmit through food chains, affecting living organisms in ecological systems. Chromium (Cr) and copper (Cu) are listed in the 11 hazardous priority substances of pollutants [1]. Cr(III) is an essential trace element for human beings and plays a role in the metabolism of glucose [2], and the toxicity of Cr(III) is small an only toxic at high concentration. Copper is a common metal in the environment. Copper is generally present in the form of Cu(II) in solution. Some metals tend to exist simultaneously in the environment. Cr(VI) and Cu(II) were chosen for two typical representatives of metal ions presented in aqueous solution, and the synchronous adsorption characteristics for
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