Equilibrium, thermodynamic, and kinetic of Cr(VI) adsorption using a modified and unmodified bentonite clay

Abstract

a b s t r a c tThe capacities of natural and modified Brazilian bentonite samples as adsorbents to remove hexavalent metal chromium were investigated under several conditions in batch and column methods. The raw material, Ca-bentonite, was modified by anchorament of 3-aminopropyltrietoxisilane (APS) and 3,2-aminoethylaminopropyltrimetoxisilane (AEAPS) in the surface of bentonite sample. This type of new occurrence of bentonite is suitable as a raw material for adsorption process. Adsorption behavior of three bentonite types was strongly depending on pH of adsorbate solution, contact time adsorbent/adsorbate, and initial concentration of Cr(VI). The results were confirmed by column method and reveals that the adsorption process of materials accorded by the Redlich-Peterson, Sips, Dubinin-Radushkevich, and Langmuir isotherm models. The exothermic enthalpic values reflected a favorable energetic process for chromium ions anchored in the material surfaces. The negative Gibbs free energy results supported the spontaneity of three adsorption reactions with Cr(VI) ions.

Effect of Structure and Chemical Activation on the Adsorption Properties of Green Clay Minerals for the Removal of Cationic Dye

“…As a consequence of these structural changes, acid-treatment can extend the fields of application of these porous solids such as in the control of atmospheric pollution [15]. This work is a continuation of numerous studies carried out in the field of surface and colloid science and dealing with clay minerals [15,[29][30][31][32][33][34][35]. Natural green clay mineral collected from south of Tunisia was treated with sulfuric acid in order to prepare suitable adsorbent for several organic compounds.…”

Effective adsorption of Cr(VI) on mesoporous Fe-functionalized Akadama clay: Optimization, selectivity, and mechanism

“…M a n u s c r i p t A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t 10 μm, and then Cr(VI) concentration in filtrate was determined . 1 The factors involved in the adsorption experiments were evaluated by full factorial 2 design (2 k ) using Design-Expert® 8.0.5 program software including ANOVA in order to 3 obtain the interactions between the process variables.…”

Anaerobic treatment and resource recovery from methanol rich waste gases and wastewaters

“…Important parameters representing the affinity between the adsorbate and adsorbent as well as maximum adsorption capacities can be calculated to gain insight into the adsorption isotherm for single and multi-component systems (Hamdaoui and Naffrechoux, 2007). The primary assumptions for the Langmuir adsorption isotherm model are: (1) adsorption is monolayer, (2) the adsorption sites are finite, localised, identical and equivalent and (3) no lateral interaction or steric hindrance occurs between the adsorbed molecules, nor between the adjacent sites (Foo and Hameed, 2010;Guerra et al, 2014).…”