title: Aminopropyltrimethoxysilane- and aminopropyltrimethoxysilane-silver-modified montmorillonite for the removal of nitrate ions.
abstract: A natural clay (Mn) modified with γ-aminopropyltrimethoxysilane (Mn-S) and silver (Mn-S-Ag) were evaluated as a potential adsorption media for nitrate removal from water. These materials were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, zeta-potential, thermogravimetric analysis, scanning electron microscopy and elemental analyses. First, the adsorption capacity of the Mn-S clay for Ag(+) was studied. The cation adsorption capacity was almost three times greater for Mn-S than for Mn because a metal-amino group complex is favored. Second, the nitrate adsorption on Mn-S and Mn-S-Ag was studied as a function of contact time, pH, temperature and adsorbent dosage using batch techniques. In the absence of Ag(+), [Formula: see text] adsorption was high at low pH and the amount of adsorbed nitrate decreased as the pH increased. For the Mn-S, the following monolayer adsorption capacities were obtained: Qmax = 0.80, 0.72 and 0.68 mmol [Formula: see text]/g at pH 3, 5 and 7, respectively, whereas for the Mn-S-Ag the values obtained were: Qmax = 0.77, 0.74 and 0.42 mmol [Formula: see text]/g at pH 3, 5 and 7, respectively. From the results obtained, [Formula: see text] adsorption occurs over [Formula: see text] surface groups without involving the Ag(+) cation in the adsorption process.
authors.affiliation: a Departamento de Química, Facultad de Ingeniería , Universidad Nacional del Comahue , Neuquén , Argentina.
authors.forename: Marcela N
authors.initials: MN
authors.lastname: Gatti
authors.affiliation: a Departamento de Química, Facultad de Ingeniería , Universidad Nacional del Comahue , Neuquén , Argentina.
authors.forename: Laura G
authors.initials: LG
authors.lastname: Fernández
authors.affiliation: a Departamento de Química, Facultad de Ingeniería , Universidad Nacional del Comahue , Neuquén , Argentina.
authors.forename: María P
authors.initials: MP
authors.lastname: Sánchez
authors.affiliation: a Departamento de Química, Facultad de Ingeniería , Universidad Nacional del Comahue , Neuquén , Argentina.
authors.forename: M Eugenia
authors.initials: ME
authors.lastname: Parolo
mesh_terms: D001546:Bentonite / Q000737:chemistry*; D009566:Nitrates / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D011437:Propylamines / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D009566:Nitrates; D011437:Propylamines; D012821:Silanes; D014874:Water Pollutants, Chemical; D001546:Bentonite; D012834:Silver; C477625:amino-propyl-triethoxysilane
keywords: Adsorption; montmorillonite; nitrate; silver; γ-aminopropyltrimethoxysilane