Afshin Maleki, Amir Hossein Mahvi, Reza Rezaee, Behrouz Davari,
Volume 5, Issue 4 (15 2013)
Abstract
Background and Objectives: Dyes are an important class of pollutants, which can even be identified by naked eye. Disposal of dyes in precious water resources have been prohibited, however, various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. Therefore, natural zeolite (clinoptilolite) and acid modified zeolite were used as a low-cost adsorbent to evaluate their ability to remove color from aqueous solution using a batch adsorption experiments.
Materials and Methods: Modification of zeolite surface was carried out with two acids sulfuric acid and phosphoric acid, to improve the removal efficiency of reactive blue 19. We studied the influence of acid concentration, contact time, solution pH, initial dye concentration, and adsorbent dosage on the removal efficiency.
Results: The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms. It was also found that adsorption of dye by zeolite followed pseudo first-order kinetics. The adsorption results indicated that natural zeolite has a limited adsorption capacity for reactive dye but can be distinctly improved by modifying its surfaces with acid. Experimental results also showed that sulfuric acid has better performance than phosphoric acid in the modification of zeolite for dye adsorption.
Conclusion: We achieved the best results in terms of removal efficiency (41-72%) for the zeolite modified with Si/Al ratio of 7.5 after 3 h of contact.
