RETRACTED: Enhanced Adsorption of Zn(II) onto Graphene Oxides Investigated Using Batch and Modeling Techniques

Abstract

Graphene oxide (GO) was synthesized and employed as an adsorbent for Zn(II) removal from an aqueous solution. The adsorption isotherms showed that Zn(II) adsorption can be better described using the Freundlich model than the Langmuir model. The maximum adsorption capacity of Zn(II) on GO determined using the Langmuir model at pH 7.0 and 293 K was 208.33 mg/g. The calculation of thermodynamic parameters revealed that the process of Zn(II) adsorption on GO was chemisorptions, endothermic, and spontaneous. Kinetic studies indicated that the pseudo-second-order kinetic model showed a better simulation of Zn(II) adsorption than the pseudo-first-order kinetic model. On the basis of surface complexation modeling, the double layer model provided a satisfactory prediction of Zn(II) by inner-sphere surface complexes (for example, SOZn+ and SOZnOH species), indicating that the interaction mechanism between Zn(II) and GO was mainly inner-sphere complexation. In terms of reusability, GO could maintain 92.23% of its initial capability after six cycles. These findings indicated that GO was a promising candidate for the immobilization and preconcentration of Zn(II) from aqueous solutions.

Adsorption of Sb (III) on Oxidized Exfoliated Graphite Nanoplatelets

“…The occurrence of Sb (III) adsorption was highlighted by the disappearance of the 1745 cm −1 vibration band, specific to the C=O group, from the oxidized graphite and the appearance of vibration bands for –COO at 1704 cm −1 , 1688 cm −1 , 1564 cm −1 , 1318 cm −1 , and 1282 cm −1 . The vibration bands specific to the C–O–C group at 1260 cm −1 , 1247 cm −1 , 1108 cm −1 and that specific to the C(O)–O group at 1051 cm −1 [26] were observed both before and after adsorption. Additionally, the absorption bands at 1517 cm −1 , 1507 cm −1 , 1494 cm −1 , and 1164 cm −1 , specific for the –CH groups, were observed after the adsorption process [27,28,29,30].…”

A New Modified Exfoliated Graphene Oxide for Removal of Copper(ii), Lead(ii) and Nickel(ii) Ions From Aqueous Solutions

“…The amounts of ∆H O and ∆S O are calculated from the slope and intercept of the straight line obtained from plotting ln K d values versus reciprocal temperature (Fig. 18), respectively, and using the following equations [10]:…”

“…∆H O , ∆S O and T are the standard enthalpy standard entropy and temperature in Kelvin, respectively, and R is the gas constant. The standard Gibbs free energy, ∆G O , of specific adsorption was calculated from the well-known equation [10]:…”

“…However, electrochemical treatment requires relatively high operating costs [9]. Between different approaches, adsorption is the most extensively used method due to its simplicity, flexibility, insensitivity to toxic substances, high efficiency in large scale applications and low cost [10][11][12][13][14]. Traditional adsorbents such as activated carbon, clay, chitosan, magnetic sorbents [15], resins [16][17][18], silica [19,20], zeolites, metal oxides and alginate suffer from poor adsorption sites, low selectivity and poor regeneration which limit their practical applications real processes.…”