title: Effects of first-row transition metals and impregnation ratios on the physicochemical properties of microwave-assisted activated carbons from wood biomass.
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, pHzpc, 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-1for Co-MC, 260 to 381m2g-1for Ni-MC, 449 to 765m2g-1for Cu-MC and from 572 to 1780m2g-1for Zn-MC. The samples showed high values of carbon contents and oxygen-containing groups. An adsorption experiment revealed that samples prepared using ZnCl2showed the highest sorption capacities (qe) for the tested adsorbates, followed by CuCl2, CoCl2and 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 (qe) of molecules followed this order: 2-nitro phenol>bisphenol A>hydroquinone>4-nitro phenol>2-naphtol>paracetamol>caffeine>resorcinol.
authors.affiliation: 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.
authors.forename: Pascal S
authors.initials: PS
authors.lastname: Thue
authors.affiliation: 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.
authors.forename: Eder C
authors.initials: EC
authors.lastname: Lima
authors.affiliation: Department of Applied Chemistry, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Sieliechi
authors.affiliation: 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.
authors.forename: Caroline
authors.initials: C
authors.lastname: Saucier
authors.affiliation: 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.
authors.forename: Silvio L P
authors.initials: SLP
authors.lastname: Dias
authors.affiliation: 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.
authors.forename: Julio C P
authors.initials: JCP
authors.lastname: Vaghetti
authors.affiliation: 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.
authors.forename: Fabiano S
authors.initials: FS
authors.lastname: Rodembusch
authors.affiliation: Federal University of Pampa, UNIPAMPA, Bagé, RS, Brazil.
authors.forename: Flávio A
authors.initials: FA
authors.lastname: Pavan
keywords: Adsorption; First-row transition metals; Microwave-assisted activated carbons; Phenols; Wood biomass