Kinetics and Thermodynamic Studies for Rhodamine B Dye Removal onto Graphene Oxide Nanosheets in Simulated Wastewater

Abstract

This report describes for the first time the kinetics, thermodynamic and optimized conditions for maximum removal of Rhodamine B in aqueous solution onto nanosheets of graphene oxides. Results from the GONS characterizations: UV, TEM, FTIR, EDX and XRD, revealed successful introduction of oxygen functionalities on the pristine graphite lattices. Adsorptive behaviour of RhB dye onto GONS under different experimental conditions such as pH, initial concentrations, adsorbent dosage, temperature, and contact time, were fully discussed in this work. The study showed that ≈93% of RhB was removed from simulated wastewater at; sorbent mass of 16.67mg; pH of 6.5; temperature of 298K; contact time of 60min; and concentrations ranging from 2.5 to 30mg/L. Experimental data tested against results of the kinetics and adsorption isotherm models, revealed that the sorption of RhB were best described by pseudo-second order and Freundlich models, respectively. Regeneration of the spent adsorbent was investigated using water, methanol and methanol/acetic acid (9:1) solution, as desorbing eluents. Methanol solution of acetic acid was observed to remove up to 94% of adsorbed RhB from GO surface compared to water (71.36%), and methanol (45.52%). The ease at which RhB was eluted from RhB-loaded GO using methanol/acetic acid (9:1), methanol and water shows that the adsorption mechanism is best described by physisorption.

High-efficiency removal of cationic dye and heavy metal ions from aqueous solution using amino-functionalized graphene oxide, adsorption isotherms, kinetics studies, and mechanism

“…Adsorption is a surface phenomenon in which adsorbates (ions or molecules) are held together by van der Waals forces (physisorption) or by forming chemical bonds (chemical adsorption) [ 45 ]. Also, adsorption mechanisms resulting from the electrostatic interaction, hydrogen bonding and π-π interaction have been reported as the primary mechanisms for graphene-based adsorbents to remove organic dyes [ 46 ]. Interestingly, various types of forces such as H-bonds, electrostatic interactions, ion exchange and π-π interactions are responsible for physical adsorption [ 47 ].…”

Adsorptive Potency of Activated Carbonized Avocado Pear Seeds (Persea Americana) and Activated Carbonized orange peels (Citrus Sinensis) in Eliminating Pb2+ ions in Contaminated Water.

“…Freundlich Isotherm model is worthwhile for non-ideal and multilayer adsorption route atop dissimilar surfaces with a non-uniform allocation of the adsorption heat on top of the surfaces (Iakovleva and Sillanpää, 2013;Lasheen et al, 2017). The Freundlich isotherm equation is shown in equation 4: log q e = loqk F + (1 𝑛 𝐹 ⁄ )logC e (4) (Bankole et al, 2019, Lim et al, 2019 The KF and nF remain the constants of Freundlich isotherm for adsorption capacity and strength, in that order. 1/nF is a dimensionless heterogeneousness factor; it's worth point to which of the adsorption route is spontaneous.…”

“…The Temkin isotherm model was based on chemisorptions notion as well as adopts that the adsorption heat of adsorbate molecules reduces linearly by means of adsorbent layer coverage owing to adsorbent-adsorbate exchanges, it similarly adopts a uniform binding energies allocation (Tie et al, 2017) B is heat of adsoption (B = RT/bT); bT (J/mol), is the Temkin isotherm constant; KT (L/g), is equilibrium binding constant as well as linked to all-out binding energy (Tie et al, 2017, Ghasemi et al, 2018, Bankole et al, 2019. Flory-Huggins isotherm is useful in describing the degree of surface coverage appearances of the adsorbate on the adsorbent, This isotherm model can state the possibility and spontaneity of an adsorption route (Almalike, 2017, Ayawei et al, 2017.…”