Synergetic and advanced isotherm investigation for the enhancement influence of zeolitization and ß-cyclodextrin hybridization on the retention efficiency of U(vi) ions by diatomite.

In synergetic investigations, the adsorption effectiveness of diatomite-based zeolitic structure (ZD) as well as its ß-cyclodextrin (CD) hybrids (CD/ZD) towards uranium ions (U(vi)) was evaluated to examine the influence of the transformation procedures. The retention behaviors and mechanistic processes have been demonstrated through analyzing the steric and energetic factors employing the modern equilibrium approach (a monolayer model with a single energy level). After the saturation phase, the uptake characteristics of U(vi) were dramatically improved to 297.5 mg g-1 after the CD blending procedure versus ZD (262.3 mg g-1) or 127.8 mg g-1. The steric analysis indicated a notable increase in binding site levels after the zeolitization steps (Nm = 85.7 mg g-1) as well as CD implementation (Nm = 91.2 mg g-1). This finding clarifies the reported improvement in the ability of CD/ZD to effectively retain the U(vi) ions. Furthermore, every single active site of the CD/ZD material has the capacity to adsorb around four ions, which are aligned according to a vertical pattern. The energetic aspects, specifically Gaussian energy (<8 kJ mol-1) along with retention energy (<40 kJ mol-1), validate the regulated influences of the physical mechanistic processes. The physical adsorption of U(vi) seems to depend on various intermolecular forces, such as van der Waals forces, in conjunction with zeolitic ion exchanging pathways (0.6-25 kJ mol-1). The thermodynamic assets have been evaluated to confirm the exothermic together with spontaneous adsorption U(vi) by ZD and its blend with CD (CD/ZD).

Steric and energetic studies on the influence of cellulose on the adsorption effectiveness of Mg trapped hydroxyapatite for enhanced remediation of chlorpyrifos and omethoate pesticides.

Magnesium-trapped hydroxyapatite (Mg.HP) was hybridized with cellulose fiber to produce a bio-composite (CLF/HP) with enhanced adsorption affinities for two types of toxic pesticides (chlorpyrifos (CF) and omethoate (OM)). The enhancement influence of the hybridized cellulose on the adsorption performances of Mg.HP was illustrated based on the determined steric and energetic factors. The computed CF and OM adsorption performances of CLF/HP during the saturation phases are 279.8 mg/g and 317.9 mg/g, respectively, which are significantly higher than the determined values using Mg/HP (143.4 mg/g (CF) and 145.3 mg/g (OM)). The steric analysis demonstrates a strong impact of the hybridization process on the reactivity of the surface of the composite. While CLF/HP reflects effective uptake site densities (Nm) of 93.3 mg/g (CF) and 135.3 mg/g (OM), the estimated values for Mg.HP are 51.2 mg/g (CF) and 46.11 mg/g (OM), which explain the reported enhancement in the adsorption performances of the composite. The capacity of each uptake site to be occupied with more than one molecule (n (CF) = 3-3.74 and n (OM) = 2.35-3.54) suggests multimolecular uptake. The energetic factors suggested physical mechanistic processes of spontaneous and exothermic behaviors either during the uptake of CF or OM.

Effective retention of cesium ions from aqueous environment using morphologically modified kaolinite nanostructures: experimental and theoretical studies.

Kaolinite can undergo a controlled morphological modification process into exfoliated nanosilicate sheets (EXK) and silicate nanotubes (KNTs). The modified structures were assessed as potential effective adsorbents for the retention of Cs+ ions. The impact of the modification process on the retention properties was assessed based on conventional and advanced equilibrium studies, considering the related steric and energetic functions. The synthetic KNTs exhibit a retention capacity of 249.7 mg g-1 as compared to EXK (199.8 mg g-1), which is significantly higher than raw kaolinite (73.8 mg g-1). The kinetic modeling demonstrates the high effectiveness of the pseudo-first-order kinetic model (R2 > 0.9) to illustrate the sequestration reactions of Cs+ ions by K, EXK, and KNTs. The enhancement effect of the modification processes can be illustrated based on the statistical investigations. The presence of active and vacant receptors enhanced greatly from 19.4 mg g-1 for KA to 40.8 mg g-1 for EXK and 46.9 mg g-1 for KNTs at 298 K. This validates the significant impact of the modification procedures on the specific surface area, reaction interface, and reacting chemical groups' exposure. This also appeared in the enhancement of the reactivity of their surfaces to be able to uptake 10 Cs+ ions by KNTs and 5 ions by EXK as compared to 4 ions by kaolinite. The thermodynamic and energetic parameters (Gaussian energy < 8.6 kJ mol-1; uptake energy < 40 kJ mol-1) show that the physical processes are dominant, which have spontaneous and exothermic properties. The synthetic EXK and KNT structures validate the high elimination performance of the retention of Cs+ either in the existence of additional anions or cations.