Removal of methylene blue dye from aqueous solutions by natural clinoptilolite and clinoptilolite modified by iron oxide nanoparticles

ABSTRACT

Adsorption techniques are widely used to remove industrial wastewater contaminants, especially non-biodegradable colourants. In this study, Iranian zeolite clinoptilolite was synthesised using magnetic iron oxide as an inexpensive and efficient adsorbent. The results showed that using natural zeolite, the removal efficiency of 26.8.6% at pH = 3 reached 48% at pH = 9. However, the adsorption capacity of the modified clinoptilolite did not change by increasing pH; it ranged from 96.4% to 98.6%. Moreover, increase in the initial concentration of the dye did not have any effects on the removal efficacy of the modified clinoptilolite. Using natural zeolite, on the other hand, the adsorption capacity showed a significant decrease and reached less than 10% at the 200 mg/l dye concentration. At the optimal contact time of 45 min, the dye removal rate by the modified zeolite was more than 98% at the optimal dose of 0.5 g. Indeed, the adsorption isotherm complied with Freundlich equation. Overall, the results showed that in comparison to the natural zeolite, the adsorption capacity of the clinoptilolite modified by iron nanoparticles increased significantly due to the uniformity of the cavities and increase in the surface of the adsorbent.

KEYWORDS:

• Modified clinoptilolite
• natural zeolite
• iron oxide nanoparticles
• methylene blue

Acknowledgements

This study was financially supported by the Research Vice-chancellor of Shiraz University of Medical Sciences. Hereby, the authors would like to thank Ms. A. Keivanshekouh at the Research Improvement Center of Shiraz University of Medical Sciences for improving the use of English in the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.