Ultrasonic-Assisted Rapid Preparation of Sulfonated Polyether Ether Ketone (PEEK) and Its Testing in Adsorption of Cationic Species from Aqueous Solutions

Abstract

Herein, we report a new approach for the sulfonation of polyether ether ketone (PEEK) following a shorter path of reaction undertaken at 60 °C under ultrasonication. The application of this method enabled the reduction of the reaction time from several hours to less than one hour, achieving a relevant sulfonation degree. The sulfonated-PEEK (SPEEK) was characterized by advanced chemical and physical instrumental methods. According to 1H-NMR analysis, the degree of sulfonation of the polymer was equal to 70.3%. Advanced microscopy (SEM) showed that the fabricated SPEEK beads (2–4 mm) were porous inside with a log-normal distribution of pore sizes within the range 1.13–151.44 μm. As an application, the SPEEK polymer was tested for the adsorption of a cationic organic pollutant (Methylene blue, MB) from aqueous solutions. The equilibrium studies (isotherms) disclosed maximum adsorption capacities of 217 mg/g, 119 mg/g, and 68 mg/g at temperatures of 323 K, 313 K, and 300 K, respectively. The thermodynamic calculations indicated an endothermic effect (ΔHad = +11.81 kJ/mol) of the investigated adsorption process. The maximum removal efficiency of 99.14% was established by process optimization using the design of experiments strategy and data-driven modeling. Additionally, molecular docking simulations were performed to disclose the mechanism of interaction at the molecular level between the adsorbent (SPEEK) and pollutant.

An Eco-Friendly Modification of a Walnut Shell Biosorbent for Increased Efficiency in Wastewater Treatment

“…The experimental data were interpolated by applying pseudo-first-order (PFO), pseudosecond-order (PSO), and intra-particle diffusion kinetic models [35,36]. The predictions by different models are represented in Figure 3 by solid, dashed, and dash-dot lines.…”

“…The corresponding non-linear regression equations and the kinetic parameters are given in given in Table S1. The chi-squared (χ 2 ) statistical test was performed to evaluate the goodness-of-fit (smaller values indicate a better agreement of the predicted data with the experiment), according to Equation (S2) in Supplementary Materials [36,37]. As observed in Figure 3 and Table S1 (χ 2 -values), the best-fitting model for MB adsorption kinetics was the PFO model, while for CV adsorption, the PSO model provided the best-fitting results.…”

“…To investigate the adsorption process, the experimental data were interpolated by Langmuir and Freundlich isotherm models [36,37], and the calculated predictions are shown in Figure 4 (solid and dashed lines). Likewise, the chi-square test (χ 2 ) was used to assess the agreement between the adsorption isotherms models and the experimental data.…”

“…(1) E S < 8 kJ/mol indicates that the adsorption process is based on physical forces (such as van der Waals); (2) E S in the range of 8-16 kJ/mol suggests an ion exchange mechanism; and (3) E S values higher than 16 kJ/mol implies chemisorption processes [36,40]. As shown in Table S2, the mean free energy (E S ) values for many of our investigated systems ranged between 9.91-16.48 kJ/mol, suggesting that the adsorption process of MB and CV could rely on ion exchange mechanisms (electrostatic interactions between the negatively charged carboxylic (−COO − ) groups from biosorbents and positively charged amino groups from dyes).…”

Characterization of the Polyetheretherketone Weldment Fabricated via Rotary Friction Welding

“…Results showed that the results obtained in this study provided a design for a PEEK actuator. Baltag et al [12] proposed a new method for the sulfonation of PEEK with a temperature of 60 • C under ultrasonication. It was found that a maximum removal efficiency of about 99% was obtained.…”