EDTA-Cross-Linked β-Cyclodextrin: An Environmentally Friendly Bifunctional Adsorbent for Simultaneous Adsorption of Metals and Cationic Dyes

Environ Sci Technol. 2015 Sep 1;49(17):10570-80. doi: 10.1021/acs.est.5b02227. Epub 2015 Aug 11.

Abstract

The discharge of metals and dyes poses a serious threat to public health and the environment. What is worse, these two hazardous pollutants are often found to coexist in industrial wastewaters, making the treatment more challenging. Herein, we report an EDTA-cross-linked β-cyclodextrin (EDTA-β-CD) bifunctional adsorbent, which was fabricated by an easy and green approach through the polycondensation reaction of β-cyclodextrin with EDTA as a cross-linker, for simultaneous adsorption of metals and dyes. In this setting, cyclodextrin cavities are expected to capture dye molecules through the formation of inclusion complexes and EDTA units as the adsorption sites for metals. The adsorbent was characterized by FT-IR, elemental analysis, SEM, EDX, ζ-potential, and TGA. In a monocomponent system, the adsorption behaviors showed a monolayer adsorption capacity of 1.241 and 1.106 mmol g(-1) for Cu(II) and Cd(II), respectively, and a heterogeneous adsorption capacity of 0.262, 0.169, and 0.280 mmol g(-1) for Methylene Blue, Safranin O, and Crystal Violet, respectively. Interestingly, the Cu(II)-dye binary experiments showed adsorption enhancement of Cu(II), but no significant effect on dyes. The simultaneous adsorption mechanism was further confirmed by FT-IR, thermodynamic study, and elemental mapping. Overall, its facile and green fabrication, efficient sorption performance, and excellent reusability indicate that EDTA-β-CD has potential for practical applications in integrative and efficient treatment of coexistenting toxic pollutants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Cations
  • Coloring Agents / isolation & purification*
  • Cross-Linking Reagents / chemistry*
  • Edetic Acid / chemistry*
  • Gentian Violet / chemistry
  • Green Chemistry Technology*
  • Hydrogen-Ion Concentration
  • Kinetics
  • Metals / isolation & purification*
  • Methylene Blue / chemistry
  • Temperature
  • Textiles
  • Waste Disposal, Fluid
  • Water Pollutants, Chemical / chemistry
  • beta-Cyclodextrins / chemistry*

Substances

  • Cations
  • Coloring Agents
  • Cross-Linking Reagents
  • Metals
  • Water Pollutants, Chemical
  • beta-Cyclodextrins
  • Edetic Acid
  • Gentian Violet
  • betadex
  • Methylene Blue