title: Production of activated carbon from biodiesel solid residues: An alternative for hazardous metal sorption from aqueous solution.
abstract: In this study, the potential for the sorption of Pb(2+) and Cd(2+) from aqueous solutions using HNO3-treated activated carbon (TAC) obtained from radish press cake (Raphanus sativus L.), a solid residue from biodiesel production, was investigated. Activated carbon (AC) was obtained by physical activation with CO2(g). Chemical modification with HNO3 was employed to increase the sorption capability of the AC. The sorption of Pb(2+) and Cd(2+) was studied in monometallic systems in equilibrium with different metal-ion concentrations (10-400 mg L(-1)). The experimental sorption equilibrium data were fit to the Langmuir and Freundlich isotherm models. The maximum sorption capacity (qmax) obtained for AC from the Langmuir isotherm was 45.5 mg g(-1) for Cd(2+) and 250 mg g(-1) for Pb(2+). Moreover, TAC presented qmax of 166.7 mg g(-1) (1.48 mmol g(-1)) for Cd(2+) and 500.0 mg g(-1) (2.41 mmol g(-1)) for Pb(2+)showing the effect of chemical modification. Sorption-desorption studies showed that the interaction between metals and TAC is reversible and this sorbent can be reused for several consecutive cycles. Furthermore, the sorption of Cd(2+) and Pb(2+) by TAC was not affected by the presence of competing ions. The experimental data obtained in this study indicated that this solid residue is viable for the production of sorbents that remove metals, such as cadmium and lead, from wastewaters and thereby contribute to the sustainable development of the production of biodiesel.
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Rita F L
authors.initials: RF
authors.lastname: Ribeiro
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Vitor C
authors.initials: VC
authors.lastname: Soares
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Letícia M
authors.initials: LM
authors.lastname: Costa
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address: clesia@qui.ufmg.br.
authors.forename: Clésia C
authors.initials: CC
authors.lastname: Nascentes
mesh_terms: D000327:Adsorption; D056804:Biofuels; D002104:Cadmium / Q000737:chemistry* / Q000302:isolation & purification; D002606:Charcoal / Q000737:chemistry*; D007854:Lead / Q000737:chemistry* / Q000302:isolation & purification; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D056804:Biofuels; D002104:Cadmium; D002606:Charcoal; D007854:Lead; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Activated carbon; Biodiesel production residue; Chemical modification; Metal sorption; Radish press cake