Effects of first-row transition metals and impregnation ratios on the physicochemical properties of microwave-assisted activated carbons from wood biomass

Pascal S Thue; Eder C Lima; Joseph M Sieliechi; Caroline Saucier; Silvio L P Dias; Julio C P Vaghetti; Fabiano S Rodembusch; Flávio A Pavan

doi:10.1016/j.jcis.2016.09.070

Effects of first-row transition metals and impregnation ratios on the physicochemical properties of microwave-assisted activated carbons from wood biomass

J Colloid Interface Sci. 2017 Jan 15:486:163-175. doi: 10.1016/j.jcis.2016.09.070. Epub 2016 Sep 29.

Authors

Pascal S Thue¹, Eder C Lima², Joseph M Sieliechi³, Caroline Saucier², Silvio L P Dias², Julio C P Vaghetti², Fabiano S Rodembusch², Flávio A Pavan⁴

Affiliations

¹ Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS, Brazil; Department of Applied Chemistry, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon. Electronic address: pascalsilasthue@gmail.com.
² Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, P.O. Box 15003, 91501-970 Porto Alegre, RS, Brazil.
³ Department of Applied Chemistry, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon.
⁴ Federal University of Pampa, UNIPAMPA, Bagé, RS, Brazil.

PMID: 27697654
DOI: 10.1016/j.jcis.2016.09.070

Abstract

First-row transition metals (Co, Ni, Cu and Zn) were successfully used in the preparation of activated carbons from wood biomass via microwave-assisted irradiation. Physical-chemical properties of the produced materials (MWAC) were studied by nitrogen adsorption-desorption curves, SEM, FTIR, UV-vis DRS and synchronous fluorescence spectroscopy, CHN elemental analysis, TGA/DTG, pH_zpc, hydrophobic properties, and total acidity and basicity groups. Results showed that the metals were bound successfully in different amounts with surface functional groups of the wood biomass through ion exchange and surface complexation interaction during the impregnation step. Zn²⁺ and Cu²⁺ formed the most complexes. MWAC impregnated with Zn²⁺ showed higher pore volumes and surface areas, followed by Cu²⁺, Co²⁺ and Ni²⁺, independently of the ratio used. As the metal : biomass ratio was increased from 0.5 to 2, the surface area of MWAC increased from 300 to 620m²g^-1 for Co-MC, 260 to 381m²g^-1 for Ni-MC, 449 to 765m²g^-1 for Cu-MC and from 572 to 1780m²g^-1 for Zn-MC. The samples showed high values of carbon contents and oxygen-containing groups. An adsorption experiment revealed that samples prepared using ZnCl₂ showed the highest sorption capacities (q_e) for the tested adsorbates, followed by CuCl₂, CoCl₂ and NiCl₂. These results matched with the surface areas and pore volumes trends, which were found to follow atomic number and melting point trends-Ni(II)<Co(II)<Cu(II)<Zn(II), rather than the Irving-Williams Series. The sorption capacities (q_e) of molecules followed this order: 2-nitro phenol>bisphenol A>hydroquinone>4-nitro phenol>2-naphtol>paracetamol>caffeine>resorcinol.

Keywords: Adsorption; First-row transition metals; Microwave-assisted activated carbons; Phenols; Wood biomass.