Title
Studies on Ag+ adsorption using two new lignocellulosic materials based on Populus alba L. and Robinia pseudoacacia L.
Authors
PAUNKA S. VASSILEVA ALBENA K. DETCHEVA TEMENUZHKA HR. RADOYKOVA IVALINA A. AVRAMOVA KATERINA I. ALEKSIEVA SANCHI K. NENKOVА IVO V. VALCHEV and DIMITAR R. MEHANDJIEV

Received The article is dedicated to the 70^th anniversary of Acad. Bogdan C. Simionescu.
Published Volume 52 Issue 7-8 July-August
Keywords adsorption of Ag+ ions, adsorption equilibrium and mechanism, fast-growing tree species wastes, hydrolyzed lignocellulosic materials

Abstract
The adsorption of Ag+ ions onto lignocellulosic materials based on two fast-growing tree species Populus alba L. (poplar) and Robinia pseudoacacia L. (black locust) was studied. Chemical analyses were performed to establish the composition of the obtained materials. Texture parameters were calculated by means of low temperature nitrogen adsorption. The adsorption mechanism was examined using IR, SEM, EPR and XPS spectroscopy. The effects of contact time, acidity and initial Ag+ ion concentrations were investigated. In both cases, the adsorption was significantly affected by the pH value. Experimental equilibrium data were fitted to the Langmuir, Freundlich and Dubinin-Radushkevich models and the corresponding constants were calculated. The obtained results revealed that the examined waste lignocellulosic materials can be used as adsorbents for Ag+ ions.