title: Modification of silica gel by attachment of 2-mercaptobenzimidazole for use in removing Hg(II) from aqueous media: a thermodynamic approach.
abstract: The compound 2-mercaptobenzimidazole (MBI) was attached onto a silica gel surface by homogeneous and heterogeneous routes. Both silica modification methodologies resulted in similar products, named SiM(hom) and SiM(het), respectively. These materials were characterized by surface area, infrared, thermogravimetry, and 13C and 29Si NMR spectroscopy. The ability of these materials to remove divalent mercury from aqueous solution was followed by a series of adsorption isotherms adjusted to a modified Langmuir equation. The maximum number of moles adsorbed was determined to be 1.35+/-0.3 and 1.42+/-0.17 mmolg-1 for SiMhet and SiMhomt, respectively. These interactions were calorimetrically followed and the thermodynamic data showed the following exothermic enthalpic values: -23.04+/-1.4 and -20.08+/-1.2 kJmol-1 for SiMhom and SiMhet, respectively. All liquid/solid interface adsorptions were spontaneous in nature and enthalpically driven.
authors.affiliation: Instituto de Química, Universidade Federal de Goiás, Caixa Postal 131, 74001-970 Goiânia, Goiás, Brazil.
authors.forename: Edésio F C
authors.initials: EF
authors.lastname: Alcântara
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Faria
authors.forename: Deyse V
authors.initials: DV
authors.lastname: Rodrigues
authors.forename: Sheila M
authors.initials: SM
authors.lastname: Evangelista
authors.forename: Edimar
authors.initials: E
authors.lastname: DeOliveira
authors.forename: Luiz F
authors.initials: LF
authors.lastname: Zara
authors.forename: Denílson
authors.initials: D
authors.lastname: Rabelo
authors.forename: Alexandre G S
authors.initials: AG
authors.lastname: Prado
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008628:Mercury / Q000737:chemistry*; D015394:Molecular Structure; D012015:Reference Standards; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D001562:Benzimidazoles; D005782:Gels; D014867:Water; C030698:2-mercaptobenzimidazole; D012822:Silicon Dioxide; D008628:Mercury