New oxygenated carbonaceous adsorbents prepared by combined radiant/microwave heating for the removal of Pb2+ in aqueous solution

Publication date: Available online 17 April 2015 Source:Journal of Analytical and Applied Pyrolysis Author(s): Gabriela Durán-Jiménez , Virginia Hernández-Montoya , Miguel A. Montes-Morán , Margarita Teutli-León This paper presents a new procedure to obtain efficient carbonaceous adsorbents for the removal of Pb2+ in aqueous solution. Experimental procedure includes a pre-treatment of pecan nut shells using radiant heating at low temperatures (280-340°C), followed by microwave radiation heating (Microwave Assist Technology: MAT) and using a L16 orthogonal array of Taguchi method to find the optimal preparation conditions, setting as the response variable the removal of Pb2+ in aqueous solution. The obtained materials were characterized using elemental analysis, FT-IR spectroscopy, potentiometric titration, nitrogen adsorption isotherms at -196°C and SEM/EDX analysis. Full Pb2+ adsorption isotherms in aqueous solution were studied using stirred batch systems at 30°C, pH 5, and using a mass to volume ratio of 2g/L. The best performing adsorbent rendered an outstanding Pb2+ sorption capacity (261mg/g), in spite of its rather low porosity. Such a high capacity was explained in terms of the materials surface chemistry, because the obtained carbons have a high amount of acidic and oxygenated groups, high calcium rich deposits. Also, the optimum conditions from each factor level in orthogonal array allowed to obtain a highly efficient carbon for Pb+2 removal.

Source: Journal of Analytical and Applied Pyrolysis - May 5, 2015 Category: Chemistry Source Type: research