Graphene Oxide-Based Fe–Mg (Hydr)oxide Nanocomposite as Heavy Metals Adsorbent

Abstract

A novel adsorbent for divalent metal cations was prepared as nanocomposite of Fe–Mg (hydr)­oxide with graphene oxide by one-step coprecipitation. This material showed adsorption selectivity of Pb2+ > Cu2+ > Ag+ > Zn2+ ≫ Co2+, Ni2+, Cd2+ with high adsorption capacity of 100–600 mg/g for Pb2+, Cu2+, Ag+, and Zn2+. Distribution coefficient (K d) was as high as ∼107 mL/g for Pb2+ and Cu2+. The adsorption isotherms for Pb2+, Cu2+, Ag+, and Zn2+ followed the Langmuir model, indicating monolayer adsorption. The adsorption kinetics for Pb2+, Cu2+, Ag+, and Zn2+ followed pseudo-second-order model, suggesting chemisorption. Removal of 50 ppm Pb2+ or Cu2+ from 100 mL solution by 0.1 g of the nanocomposite was over 99.7%. The thermodynamics studies implied that the adsorption process toward heavy metals was spontaneous and endothermic. Together with recyclability through magnetic separation, this adsorbent would be useful in polluted water processing.

Facile Synthesis of Phytic Acid Impregnated Polyaniline for Enhanced U(VI) Adsorption

“…To obtain the adsorption process mechanism of U­(VI) onto PA-PANI-3, two adsorption kinetics models, namely, pseudo-first-order and pseudo-second-order kinetic models were used to fit the data. ,, The relevant equations are expressed as follows: where q t (mg/g) and q e are the adsorption capcities of U­(VI) at contact time t and at equilibrium time. k 1 (1/min) and k 2 (g/(mg/min)) are the rate constants of the pseudo-first-order and the pseudo-second-order kinetic models, respectively.…”

“…Moreover, the adsorption thermodynamics have been studied. The thermodynamic parameters including enthalpy change (Δ H , kJ/mol), entropy change (Δ S , J/mol/K), and Gibbs free energy (Δ G , kJ/mol) are calculated by the following equations: ,,, where K d (mL/g) is the distribution coefficient. T (K) and R (8.314J/mol/K) are the absolute temperature and the ideal gas constant, respectively.…”

“…To obtain the adsorption process mechanism of U(VI) onto PA-PANI-3, two adsorption kinetics models, namely, pseudofirst-order and pseudo-second-order kinetic models were used to fit the data. 2,25,27 The relevant equations are expressed as follows:…”

Evolution of graphene oxide (GO)-based nanohybrid materials with diverse compositions: an overview

“…The physical adsorption of Congo Red (CR) dye took place on the nanocomposite and it happened due to electrostatic interaction between the moieties with opposite charge. In 2018 D. Huang et al 207 prepared double oxide of Fe–Mg hydroxide nanoparticles and uniformly loaded it on GO by the co-precipitation method. The prepared nanocomposite showed high adsorption capacity to heavy metals and selectivity towards Pb 2+ and Cu 2+ .…”

Facile Synthesis of Novel Rare-Earth Elements-Modified SiO2 Films for Effective Cr(VI) Removal from Electroplating Effluent

“…Therefore, it is of great scientific and practical significance to develop effective methods for Cr­(VI) removal . Nowadays, the methods for wastewater treatment include photocatalysis, ion exchange, biological treatment, adsorption, and so forth. Compared with other methods, adsorption has the advantages of high efficiency, wide application, and simple operation …”