Adsorption of Fe(III) from water by natural and acid activated clays: Studies on equilibrium isotherm, kinetics and thermodynamics of interactions

Abstract

The present work investigates the removal of Fe(III) ions from an aqueous solution by kaolinite, montmorillonite and their acid activated forms. The specific surface areas of kaolinite, acid activated kaolinite, montmorillonite and acid activated montmorillonite were 3.8, 15.6, 19.8 and 52.3 m 2 /g respectively whereas the cation exchange capacity (CEC) was measured as 11.3, 12.2, 153.0, and 341.0 meq/100 g for four clay adsorbents respectively. Adsorption increased with pH till Fe(III) became insoluble at pH > 4.0. The kinetics of the interactions is not certain, but the second order kinetics (k 2 = 4.7 × 10 −2 to 7.4 × 10 −2 g mg −1 min −1 ) appears to give a better description. Langmuir and Freundlich isotherms were applied and isotherm coefficients were computed. The Langmuir monolayer capacity of the clay adsorbents was from 11.2 to 30.0 mg g −1 . The process was exothermic with H in the range of −27.6 to −42.2 kJ mol −1 accompanied by decrease in entropy ( S = −86.6 to −131.8 J mol −1 K −1 ) and decrease in Gibbs energy. The results have shown that kaolinite, montmorillonite and their acid activated forms could be used as adsorbents for separation of Fe(III) from aqueous solution. Acid activation enhanced the adsorption capacity compared to the untreated clay minerals.

Influence of Acid Activation on Natural Calcium Montmorillonite Clay

“…1 It shows bleaching action 2,3 and also can be effectively used as adsorbent for adsorption of harmful substances like dye 4,5 , heavy metal ions 6,7 from their sources. Its adsorption capacity as adsorbent and bleaching action can be increased manifold if it is activated particularly with acid.…”

Efficiency of Pb(II) and Mo(VI) Removal by Kaolinite Impregnated with Zero-Valent Iron Particles

“…Multiple methods of their modification are known, which have led to the improvement of their sorption properties. Many conventional and unconventional adsorbents have been used for heavy metals' removal, including layered double hydroxides (LDH) (You et al 2001;Hudcova et al 2016), clay minerals (Suraj et al 1998;Bhattacharyya, Gupta 2006;Zhang, Hou 2008;Üzüm et al 2009), zeolites (Erdem et al 2004;Szala et al 2015), activated carbon (Patnukao et al 2008;Xu et al 2008), and graphene oxides (Ren et al 2013;Liu et al 2014).…”

Adsorption Characteristic of Iron Onto Poly[eugenol-Co-(Divinyl Benzene)] From Aqueous Solution

“…The chemical bonding occurred between the adsorbate and the adsorbent is quite strong, and then when the adsorbent surface is covered by the adsorbate, adsorbent will not adsorb another adsorbate, although the temperature and concentration increase. Langmuir isotherms obtain the adsorption capacity (Qmax) 250 mg.g -1 , it value is better compared to chitin, chitosan, clay, raphia palm fruit endocarp and chitosan/antapulgite composite which respectively have 1,4537; 90,09; 30,0; 16,3500; 62,50 mg.g -1 [6,7,11,12]. Then the equilibrium obtains value 0.8 L. mg -1 (Fig.…”

“…Adsorption is one of the most effective and simple methods for treatment of hazardous toxic waste from solution and an economically viable alternative if a low-cost adsorbent is utilized [7,8,9]. The study on Fe metal ion adsorption has also been performed using various natural materials, such as natural zeolite and modified zeolite [10], chitin, natural clay and activated clay [6], unmodified raphia palm [11], chitosan/ attapulgite composite [12], and maize husk [5]. In addition, there are still many other natural materials.…”

“…The necessary of Iron for normal function in the human body is in the range of 3000-5000 mg. Fe as a secondary contaminant with the recommended limit of 0.3 mg/L according to the U.S. EPA,. The excess of Iron can cause hepatomia, which is the primary cancer of liver that becomes the most common cause of death among patients with hemochromatosis, and can damage to the gastrointestinal track and liver [4,6]. The recovery of heavy metals can be done by various methods such as chemical precipitation, ion exchange, electrochemistry removal, membrane separation, and adsorption.…”