期刊
WATER RESEARCH
卷 160, 期 -, 页码 148-157出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2019.05.055
关键词
Heavy metal; Wastewater treatment; Clay-based materials; Cr(VI) removal mechanism; Pyrrolic nitrogen
资金
- National Natural Science Foundation of China [51374157]
- Program for New Century Excellent Talents in University [NCET-12-0713]
Chromate is considered to be a toxic contaminant because of its potential to harm animal and human health. In this study, polypyrrole/calcium rectorite clay composites (PPy/Ca-REC composites) were prepared as a potential adsorbent, via in situ polymerization of pyrrole monomer for adsorption of Cr(VI) from aqueous solution. The XRD results indicated that the clay sheets were exfoliated in the prepared composites. SEM results showed good dispersion of the PPy on the clay sheets. The adsorption of Cr(VI) onto the PPy/Ca-REC adsorbent was highly pH-dependent, and the removal efficiency by PPy/Ca-REC composites was much higher than the PPy homopolymer. Adsorption kinetics followed a pseudo-second-order kinetic model with an equilibrium reached within 30-180 min. The adsorption isotherm data were fitted well by the Langmuir isotherm model with the maximum adsorption capacity of 714.29-833.33 mg/g at 25-45 degrees C. The PPy/Ca-REC composites could be regenerated and reused for three consecutive adsorption-desorption cycles without loss of the original removal efficiency for Cr(VI) removal. Furthermore, the selective adsorption of Cr(VI) was demonstrated in binary adsorption systems with coexisting ions. The mechanisms of Cr(VI) removal containing electrostatic interactions, ionic interaction as well as reduction of Cr(VI) to Cr(III), which could be observed by the XPS results. (C) 2019 Elsevier Ltd. All rights reserved.
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