Adsorption of Brilliant Green Dye onto a Mercerized Biosorbent: Kinetic, Thermodynamic, and Molecular Docking Studies

Abstract

This study reports the valorization of pistachio shell agricultural waste, aiming to develop an eco-friendly and cost-effective biosorbent for cationic brilliant green (BG) dye adsorption from aqueous media. Pistachio shells were mercerized in an alkaline environment, resulting in the treated adsorbent (PSNaOH). The morphological and structural features of the adsorbent were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, and polarized light microscopy. The pseudo-first-order (PFO) kinetic model best described the adsorption kinetics of the BG cationic dye onto PSNaOH biosorbents. In turn, the equilibrium data were best fitted to the Sips isotherm model. The maximum adsorption capacity decreased with temperature (from 52.42 mg/g at 300 K to 46.42 mg/g at 330 K). The isotherm parameters indicated improved affinity between the biosorbent surface and BG molecules at lower temperatures (300 K). The thermodynamic parameters estimated on the basis of the two approaches indicated a spontaneous (ΔG < 0) and exothermic (ΔH < 0) adsorption process. The design of experiments (DoE) and the response surface methodology (RSM) were employed to establish optimal conditions (sorbent dose (SD) = 4.0 g/L and initial concentration (C0) = 10.1 mg/L), yielding removal efficiency of 98.78%. Molecular docking simulations were performed to disclose the intermolecular interactions between the BG dye and lignocellulose-based adsorbent.

Yeast-Based Magnetic Biocomposite for Efficient Sorption of Organic Pollutants

“…After completing the sorption process, YL-M-L-AC was separated from the solution using an external magnetic field, and then the concentration of MB in the solution was determined. The modified Langmuir equilibrium coefficient (K ML ), a dimensionless parameter calculated for the tested temperatures, was applied for the calculation of the thermodynamic parameter from the van't Hoff equation [28][29][30]:…”

Dynamic Adsorption of a Cationic Dye onto Wool Fibers as Column-Filling Media: Response Surface Optimization and Fixed-Bed Adsorption Modeling

“…Batch adsorption experiments were also performed to assess the thermodynamic parameters (Gibbs free energy ∆G ad , enthalpy ∆H ad , and entropy ∆S ad ) of the process. Hence, the change in the Gibbs free energy of adsorption (∆G ad ) was ascertained as [16,17]…”

“…where T denotes the absolute temperature (K), R g is the universal gas constant (R g = 8.314 J/(K•mol)), and K ML is the modified Langmuir constant according to the revised isotherm [16]. Assuming the Va not Hoff isochore equation, the change in the enthalpy of adsorption (∆H ad ) can be assessed as follows [17]:…”

“…Ultimately, the variation of the adsorption entropy (∆S ad ) was calculated from the basic thermodynamic equation as [17] ∆S ad = ∆H ad − ∆G ad T (4)…”

“…Materials 2024, 17, x FOR PEER REVIEW [16]. Assuming the Va not Hoff isochore equation, the change in the enthalpy of ad tion (ΔHad) can be assessed as follows [17]:…”