Eco-Friendly Synthesis and Characterization of Double-Crossed Link 3D Graphene Oxide Functionalized With Chitosan for Adsorption of Sulfamethazine From Aqueous Solution: Experimental and DFT Calculations

Abstract

Graphene oxide–chitosan composites are attracting considerable interest as an eco-friendly adsorbent material for most aquatic environmental pollutants. Today, the focus is on the emerging applications of 2D and 3D graphene functionalized with chitosan to enhance its mechanical properties and adsorption efficiency. Herein, the super adsorbent 3D graphene functionalized with chitosan (3D GF-CS) is synthesized to remove sulfamethazine, (SMZ) as a model aquatic antibiotic pharmaceutical. The synthesized materials were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photon spectroscopy (XPS), Brunauer–Emmett–Teller (BET), and Raman spectroscopy. After that, adsorption experiments were conducted for SMZ adsorption to find out the optimized adsorption parameters, such as pH, temperature, contact time, initial antibiotic concentration, and adsorbent dosage. The results show the optimal adsorption parameters were as pH of 7, temperature of 25°C, initial antibiotic concentration Ci of 50 ppm. Also, the kinetics, isotherms models, and thermodynamics parameters of SMZ adsorption were studied. The experimental results revealed to be best suited by both the pseudo-second-order kinetic and the Freundlich isotherm model compared with other isotherm models. The thermodynamics parameters demonstrated that the adsorption is exothermic, exhibiting higher adsorption efficiency at lower temperature. In addition, Gibb’s free energy suggested the adsorption to be spontaneous as well as entropy indication of the loss of disorder. Furthermore, the regeneration of 3D GF-CS was utilized in ten consecutive cycles, and the SMZ adsorption capacity did not decline significantly. Additionally, this research studied the adsorption energies and how sulfamethazine adsorbs onto 3D GF-CS was determined by applying the density-functional–based tight binding (DFTB) and Monte Carlo simulations at different adsorption positions. The chemical reactivity (local and global) of the free drug was investigated using the density functional theory (DFT), namely, the B3LYP and PBEPBE functionals with the 6–31+G (d, p) basis set in the gas phase and aqueous solution.

Adsorption of Methylene Blue Dye and Analysis of Two Clays: A Study of Kinetics, Thermodynamics, and Modeling with DFT, MD, and MC Simulations

“…Adsorbed adsorbate molecules on SiO 2 and calcite surfaces showing a considerable increase in negative E ads values is indicative of adsorbate molecules’ strong binding to and preferential adsorption by adsorbent surfaces. ,,, The data presented here lend credence to the hypothesis that the adsorbent serves as a superior substrate for efficient adsorption, which may result in greater adsorption capacities and better performance in appropriate uses . Since there was only a little amount of temperature drift during the MD simulation, we may be confident that our results will hold up (Figure b). − , …”

“…66 Since there was only a little amount of temperature drift during the MD simulation, we may be confident that our results will hold up (Figure 17b). [59][60][61]75 The simulations are more credible and valid since they coincide with experimental observations. With the MB molecules' effective adherence to the surfaces as a starting point, a consistent and accurate picture of the MB-surface interactions may be constructed.…”

Chitosan-Hydroxyapatite Bio-Based Composite in Film Form: Synthesis and Application in Wastewater

“…The value of ΔG° falls as temperature rises, indicating that adsorption is spontaneous for both metal ions Cd 2+ and Zn 2+ , and the value of the standard enthalpy ΔH° is positive, which shows that the adsorption is endothermic [ 47 , 48 , 49 , 50 , 51 ].…”

Adsorption and Inhibition Mechanisms of New Pyrazole Derivatives for Carbon Steel Corrosion in Hydrochloric Acid Solutions Based on Experimental, Computational, and Theoretical Calculations

“…The fraction of electrons transferred (ΔN 110 ) values provides useful information on the tendency of the electrons to flow from the inhibitor molecule to the CS surface (ΔN > 0) or from the CS to the inhibitor (ΔN < 0). 71 In this computation, the L4 molecule (ΔN 110 = 0.176) is more likely to share its electron to form coordination bonds with Fe(110). In contrast, L4H + and L6H + do not show this attitude, which may be influenced by protonation of the nitrogen atom.…”