Investigation of Ammonium and Nitrite Removal by Zeolite Material Synthesized on Red Mud Base

Abstract

The zeolite with the unit formula of Na8(Al6Si6O24)S.4H2O was synthesized directly on red mud base with addition of single silicon (signed as RH-ZeO-Si) and both silicon and aluminum portions (signed as RM-ZeO-SiAl) to original Tan Rai (Vietnam) red mud. The structure of the zeolite was studied by X-Ray difration and FT-IR absorption spectra. The synthesized materials were studied on their adsorption ability of ammonium and nitrite ions. The results showed that, the adsorption of ammonium cation was mostly allowing ion-exchange mechanism and the zeolite crystaline forms played predominantly role besids minor one of single metal oxides. For nitrite anions, it is otherwise, the adsorption mechanism was mostly leant to electrostatic attraction between nitrite anions and electropositive effect of the hematite surface in light acidic condition. The adsorption isotherms of all ammonium and nitrite ions on both synthesized materials were nearly conformable with Freundlich model than Langmuir model. Those showed that, both materials have unhomogeneous adsorption surface. The maximum adsorption capacity of ammonium and nitrite on RM-ZeO-Si was 5.71 mg/g and 2.73 mg/g respectively, and on RM-ZeO-SiAl was 5.61 mg/g and 3.12 mg/g respectively. The initial test of competitive ions influencing on adsorption ability showed that, for all cases the competition of cations to ammonium ion was more significance than those of anions to nitrite ion in the same conditions.

Keywords

• ammonium and nitrite adsorption
• zeolite
• Tan Rai red mud