Removal of tetrabromobisphenol-A from aqueous solution by Al₁₃-Montmorillonite modified with different types of surfactants and transition metals

Abstract

In this study, remediation of tetrabromobisphenol-A (TBBPA) from aqueous solution by sorption using transition metals-modified inorganic–organic montmorillonite (IOMt) was demonstrated. The adsorbents were prepared in two steps: (1) intercalation of surfactants into Al₁₃-pillared montmorillonite for synthesizing two types of IOMt; (2) incorporation of transition metals (Cu²⁺, Ni²⁺, or Co²⁺) onto those IOMts. Firstly, these materials were characterized by XRD, FTIR, TGA, SEM-EDS, and BET analyses. Then, experiments were conducted on the sorption isotherms, kinetics, and thermodynamics of TBBPA. In general, sorption process with Cu- and Ni-modified IOMt achieved higher TBBPA removal efficiency than sorption process with original IOMt. The modified IOMt displayed the sorption capacity that varied depending on TBBPA initial concentration, pH, and metals loading. However, the type of surfactants did not influence TBBPA sorption on metals-modified IOMt. This probably indicated that complex interaction between TBBPA and metals rather than hydrophobicity plays a key factor in TBBPA sorption process. Equilibrium data could be well interpreted by the Freundlich model, and the rate of sorption was adjusted to a pseudo-second-order kinetic model. The negative values of Gibbs energy change (∆G) and positive values of enthalpy change (∆H) indicated the spontaneous and endothermic nature of process.

Keywords:

• Transition metals
• Montmorillonite
• TBBPA
• Sorption
• Inorganic–organic

Acknowledgment

This work was supported in part by the Grant from the Environmental and Pollution Control Technology and National Key Scientific and Technological Project ‘‘Water Pollution Control and Treatment’’ (2012ZX07206002) (2012ZX07206004).