Equilibrium and kinetics studies for the adsorption of Ni²⁺ and Fe³⁺ ions from aqueous solution by graphene oxide

Abstract

In this study, the adsorption of Ni 2+ and Fe 3+ metal ions from aqueous solutions onto graphene oxide (GO) have been explored. The effects of various experimental factors such as pH of the solution, initial metal ion concentration and temperature were evaluated. The kinetic, equilibrium and thermodynamic studies were also investigated. The adsorption rate data were analyzed using the pseudo-fi rst-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model. Kinetic studies indicate that the adsorption of both ions follows the pseudo-second-order kinetics. The isotherms of adsorption data were analyzed by adsorption isotherm models such as Langmuir and Freundlich. Equilibrium data fi tted well with the Langmuir model. The maximum adsorption capacities of Ni 2+ and Fe 3+ onto GO were 35.6 and 27.3 mg g -1 , respectively. In addition, various thermodynamic parameters, such as enthalpy (ΔHO), entropy (ΔSO) and Gibbs free energy (ΔGO), were calculated.

The cross-talk between lateral sheet dimensions of pristine graphene oxide nanoparticles and Ni2+ adsorption

“…and may be precipitated onto the surface of GO particles. 1,38 The lateral sheet dimension (GO -200 nm) shows higher removal comparing with GO -450 nm. This behavior is attributed to more surfaces of GO particles.…”

“…In panel (b) the size of GO particles (GO -200 nm) shows higher removal of Ni 2+ due to increasing adsorbate surfaces. 1,24 The removal of Ni 2+ percent was calculated by using the following eqn (2):…”

“…R L value indicates the adsorption reliable if R L > 1 unfavorable, 0 < R L < 1 favorable, R L ¼ 1 for linear adsorption, and R L ¼ 0 for irreversible adsorption. 1 The Freundlich model is an empirical equation consider that adsorption of metal ions occurs on heterogeneous surface by multilayer adsorption; the linear form of Freundlich can be expressed in eqn (5).…”

“…Graphene oxide (GO) has been investigated as an extraordinary next-generation adsorbent in water and wastewater purication. [1][2][3] The neat structure and outstanding physicochemical characteristics of GO have attracted enormous attention from researchers for use in several elds of technology, such as energy, biology, medicine, and water. 2,[4][5][6][7][8][9][10][11][12][13][14] GO is a twodimensional layer of sp 2 hybridized carbon atoms decorated with abundant oxygen groups like carboxyl, hydroxyl, epoxy, etc., these groups have the ability to bind with organic and inorganic substances with both chemical and/or physical interactions.…”

Facile fabrication of highly flexible and floatable Cu2O/rGO on Vietnamese traditional paper toward high-performance solar-light-driven photocatalytic degradation of ciprofloxacin antibiotic

“…The range of the n value from 1 to 10 implied that the adsorption was favorable. 31 The tting of the experimental data with the adsorption models and isotherm models are shown in Fig. 3e and f, respectively.…”