Kinetic and thermodynamic study on adsorption of cadmium from aqueous solutions using natural clay

Potent and Versatile Biogenically Synthesized Alumina/Nickel Oxide Nanocomposite Adsorbent for Defluoridation of Drinking Water

In the present work, an extract of Salvia officinalis leaves was used to synthesize an alumina/NiO nanocomposite by the coprecipitation method. First, the shape and surface content of the synthesized adsorbent were determined. Scanning electron microscopy images showed the production of nanospheres and nanorods with sizes between 35 and 50 nm. X-ray diffraction measurement revealed strong, high-intensity peaks, confirming the preparation of a highly crystalline alumina/nickel oxide nanocomposite. Then, the pure nanoalumina, nickel oxide, and functionalized alumina/nickel oxide nanocomposite for water defluoridation were investigated under various conditions, for example, stirring period, pH, and initial fluoride concentration. Defluoridation with greener alumina, nickel oxide, and alumina/nickel oxide nanocomposite lasted 120 min at adsorbent dosages of 0.8 g/L in a pH 7 solution. The adoption process for the three sorbents matches the Langmuir adsorption isotherm. The process dynamics were explored using pseudo-second-order and first-order kinetics. The water quality after treatment met drinking water requirements, proving the viability of using nanoparticles for drinking water defluoridation. This work confirmed effective water defluoridation in the crystalline phase using synthesized nanoalumina, nickel oxide, and their nanocomposite, which highlights their importance for future drinking water defluoridation.

Exploring the Efficiency of Algerian Kaolinite Clay in the Adsorption of Cr(III) from Aqueous Solutions: Experimental and Computational Insights

The current study comprehensively investigates the adsorption behavior of chromium (Cr(III)) in wastewater using Algerian kaolinite clay. The structural and textural properties of the kaolinite clay are extensively characterized through a range of analytical methods, including XRD, FTIR, SEM-EDS, XPS, laser granulometry, N2 adsorption isotherm, and TGA-DTA. The point of zero charge and zeta potential are also assessed. Chromium adsorption reached equilibrium within five minutes, achieving a maximum removal rate of 99% at pH 5. Adsorption equilibrium is modeled using the Langmuir, Freundlich, Temkin, Elovich, and Dubinin-Radushkevitch equations, with the Langmuir isotherm accurately describing the adsorption process and yielding a maximum adsorption capacity of 8.422 mg/g for Cr(III). Thermodynamic parameters suggest the spontaneous and endothermic nature of Cr(III) sorption, with an activation energy of 26.665 kJ/mol, indicating the importance of diffusion in the sorption process. Furthermore, advanced DFT computations, including COSMO-RS, molecular orbitals, IGM, RDG, and QTAIM analyses, are conducted to elucidate the nature of adsorption, revealing strong binding interactions between Cr(III) ions and the kaolinite surface. The integration of theoretical and experimental data not only enhances the understanding of Cr(III) removal using kaolinite but also demonstrates the effectiveness of this clay adsorbent for wastewater treatment. Furthermore, this study highlights the synergistic application of empirical research and computational modeling in elucidating complex adsorption processes.