Simultaneous removal of dyes and metal cations using an acid, acid-base and base modified vermiculite as a sustainable and recyclable adsorbent.

The aim of this work was the modification of vermiculite in order to produce a low cost, efficient and sustainable adsorbent for dyes and metals. Three activation methods consisting of acid, base and combined acid/base treatment were applied to improve the of vermiculite's adsorption properties. Adsorbents were tested in single, bi- and tricomponent solutions containing cationic dyes and Cu cations. The raw material showed low adsorption capacity for dyes and metal. The acid/base treated vermiculite had very good adsorption capacity toward dyes while the maximum adsorption capacity for Cu did not change comparing to the starting material. The alkaline treated vermiculite was a good adsorbent for metals, while still being able to remove dyes on the level of the not treated material. Moreover, it was shown that the materials may be regenerated and used in several adsorption-desorption cycles. Furthermore, it was possible to separate adsorbed dyes from metals that were desorbed, using as eluents ethanol/NaCl and 0.05M HNO, respectively. This opens a possibility for sustainable disposal and neutralization of both of the pollutants or for their further applications in other processes.