[Effect of Cr (VI) anions on the Cu (II) adsorption behavior of two kinds of clay minerals in single and binary solution].
The adsorption of Cu (II) on kaolinite and montmorillonite was investigated through batch adsorption experiment. Several adsorption models were employed to describe the adsorption of Cu (II) on the two clay minerals in single Cu (II) and Cu(II)-Cr (VI) binary solutions, and the impact of solution with various pH values on the adsorption of Cu (II) on the two target mineral clays was investigated in order to explain the environmental chemical behavior of heavy metals in soil and to provide theoretical basis in remediation of multi-element contaminated soil. The results indicated that the adsorption process of Cu (II) on kaolinite and montmorillonite in both single and binary solutions was fast at the beginning and then slowed down. Adsorption equilibrium was observed within 120 min. In both single and binary solutions, pseudo-second-order model (R2 > 0.983) showed the highest agreement with the adsorption of Cu (II) on the two mineral clays, followed by the intra-particle diffusion model and pseudo-first-order model. Both Intra-particle diffusion model and Boyd model illustrated that the film diffusion process was the rate-limiting step, which mainly occurred at the edge and surface of mineral clays. Copper adsorption on kaolinite was well fitted with the Freundlich equation (R2 > 0.971), which could be attributed to the heterogeneity of kaolinite surface with adsorption sites that have different energies of adsorption. Langmuir equation was best fitted with the isotherm for montmorillonite (R2 > 0.983), which indicated that the adsorption was on a single molecular layer or chemisorptions. In both single and binary solutions, the adsorption of Cu (II ) on the two clay minerals first increased and then decreased with the rising of pH values. The maximum adsorption amount was found at pH = 5.0, and was in the order of Qmon. > Qkao. and Q(Single-Cu) > Q(Cu-Cr binary). Cr (VI) in the solution reduced the adsorption of Cu (II), and the minimal influence of Cr (VI) on Cu (I) adsorption was observed at pH = 6.0.
Juan-Juan
JJ
Liu
Dong-Li
DL
Liang
Xiao-Long
XL
Wu
Guang-Zhou
GZ
Qu
Xun
X
Qian
D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D000077215:Clay; D003300:Copper / Q000737:chemistry*; D004058:Diffusion; D007616:Kaolin / Q000737:chemistry*; D012996:Solutions
D000538:Aluminum Silicates; D012996:Solutions; D002857:Chromium; D001546:Bentonite; C074702:chromium hexavalent ion; D007616:Kaolin; D003300:Copper; D000077215:Clay