Removal of Cr(VI) from aqueous solutions by adsorption on MnO2
Removal of Cr(VI) from aqueous solutions by adsorption on MnO2
复制标题
DOI：
10.1016/j.jhazmat.2016.02.042
复制
发表时间：
2016-06-05
影响因子：
13.6
通讯作者：
Mosoarca, Giannin
中科院分区：
文献类型：
--
作者：
Gheju, Marius;Balcu, Ionel;Mosoarca, Giannin
研究了 Cr(VI) 在 MnO2 上的吸附，包括 pH、温度、离子强度、初始 Cr(VI) 浓度、不同阴离子（HCO3-、SO42-、H2PO4-、NO3- 和 Cl-）和低分子量天然有机材料 (LMWNOM)（乙酸根、草酸根和柠檬酸根）共存的影响。该过程在前 3-5 分钟内很快，一小时后达到平衡。吸附随着 pH、温度和 Cr(VI) 初始浓度的增加而降低，并随着离子强度的增加而增加。磷酸盐、硫酸盐、碳酸氢盐、柠檬酸盐和草酸盐的共存阻碍了Cr(VI)的吸附，而硝酸盐、氯化物和乙酸盐没有产生任何显着影响。阴离子和 LMWNOM 共存对 Cr(VI) 吸附抑制的总体顺序分别为 H2PO4 > HCO3- > SO42- 和草酸盐 > 柠檬酸盐。在20℃、pH 5.9时获得最高的实验平衡吸附容量(0.83 mg g(-1))，而在H2PO4-共存、20℃、pH 6.9时观察到最低(0.18 mg g(-1))。通过伪二阶模型成功拟合了吸附动力学。可能涉及特异性和非特异性吸附机制，而速率控制步骤涉及颗粒内和薄膜扩散过程。 Cr(VI) 与 MnO2 牢固结合，这使得其随后释放到环境中的风险较低。 (C) 2016 Elsevier B.V. 保留所有权利。
Adsorption of Cr(VI) on MnO2 was investigated with respect to effect of pH, temperature, ionic strength, initial Cr(VI) concentration, co-presence of different anions (HCO3-, SO42-, H2PO4-, NO3- and Cl-) and of low molecular weight natural organic materials (LMWNOM) (acetate, oxalate and citrate). The process was rapid during the first 3-5 min, reaching equilibrium after one hour. Adsorption decreased with increasing pH, temperature and Cr(Vl) initial concentration, and increased with increasing ionic strength. Co-presence of phosphate, sulfate, bicarbonate, citrate and oxalate hindered Cr(VI) adsorption, whereas nitrate, chloride and acetate did not exert any notable influence. The overall order of Cr(VI) adsorption suppression due to co-presence of anions and LMWNOM was H2PO4 > HCO3- > SO42-, and oxalate > citrate, respectively. Highest experimental equilibrium sorption capacity (0.83 mg g(-1)) was obtained at 20 degrees C and pH 5.9, while lowest (0.18 mg g(-1)) was noticed in the co-presence of H2PO4-, at 20 degrees C and pH 6.9. Adsorption kinetics was successfully fitted by pseudo-second-order model. Mechanisms for both specific and non-specific adsorption are likely to be involved, while rate-controlling step involved both intra-particle and film diffusion processes. Cr(VI) was strongly bound to MnO2, which makes risks of its subsequent liberation into the environment to be low. (C) 2016 Elsevier B.V. All rights reserved.