Spent tea leaves as a potential low-cost adsorbent for the removal of azo dyes from wastewater

Antonio Zuorro
Roberto Lavecchia
Franco Medici
Luigi Piga

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Publication date

January 2013

DOI

10.3303/cet1332004

Publisher

AIDIC - Italian Association of Chemical Engineering

Abstract

Spent tea leaves (STL), a solid waste that is available in large amounts worldwide, was investigated as a potential low-cost adsorbent for the removal of two azo dyes, Reactive Green 19 (RG19) and Reactive Violet 5 (RV5), from contaminated waters. Preliminary experiments conducted on untreated STL showed that this material exhibited very low removal efficiencies (<10 %). By contrast, thermal activation of STL (200 to 400 C° for up to 2 h) resulted in a significant increase in dye adsorption. After thermal exposure of STL to 300 C° for 1 hour, removal efficiencies of 98.8 % and 72.8 % were observed, respectively, for RG19 and RV5. Characterization of the adsorbent by TG/DTA and FTIR measurements showed that structural and chemical changes oc...