Rapid Synthesis of Kaolinite Nanoscrolls through Microwave Processing

Engineering high-performance CTAB-functionalized magnesium silicate nano-adsorbent for efficient removal of Cd2+, Co2+, and Cu2+ from single-metal aqueous solutions

The development of highly efficient, recyclable adsorbents for heavy metal remediation remains a critical challenge in environmental engineering. This study introduces a novel cetyltrimethylammonium bromide-functionalized magnesium silicate (CTAB/MS) nano-adsorbent was synthesized through a multi-step surface modification of serpentinite involving intercalation with dimethyl sulfoxide, methanol treatment, and CTAB incorporation. The resulting nanostructure was extensively characterized and applied for the removal of cadmium (Cd2+), cobalt (Co2+), and copper (Cu2+) ions from contaminated water. The characterization findings confirmed significant morphological and structural modifications, including enhanced surface area, functional group availability, and mesoporosity, which contributed to enhanced adsorption performance. The kinetic modeling confirmed that the process predominantly followed a pseudo-first-order model, suggesting that rapid physisorption mechanisms controlled the initial adsorption phase. Equilibrium studies revealed that adsorption followed the Langmuir isotherm model, indicating monolayer adsorption on homogeneous active sites, with maximum adsorption capacities of 491.9 mg/g (Cd2+), 481.8 mg/g (Co2+), and 434.3 mg/g (Cu2+) at 303 K. Furthermore, statistical physics-based isotherm model incorporating steric and energetic parameters provided deeper mechanistic insights. The adsorption energy (ΔE) values remained below 12.66 kJ/mol, confirming a predominantly physical adsorption process, while thermodynamic analysis indicated an exothermic and spontaneous nature, as evidenced by negative free enthalpy (G) and internal energy (Eint) values. The recyclability assessment demonstrated that CTAB/MS retained over 70% of its adsorption efficiency after five consecutive regeneration cycles, underscoring its long-term applicability in water treatment. This highlights the potential of CTAB/MS as an advanced, cost-effective, and sustainable solution for large-scale water purification.

Role of Impurities in Kaolinite Intercalation and Subsequent Formation of Nanoscrolls

Kaolinite (Kaol)-methanol (MeOH) compounds (Kaol-Me) are widely used as the starting materials for further intercalation. The conventional approach to prepare Kaol-Me compounds is to wash dimethyl sulfoxide (DMSO)-intercalated Kaol (Kaol-DMSO) for 16 days, and MeOH must be refreshed every day. Herein, we report a new and much more efficient method to prepare Kaol-Me from Kaol-DMSO by the promotion of AlCl3 under mild conditions, and the corresponding mechanism is investigated. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and X-ray fluorescence characterization results reveal that the electric double layer resulting from the impurities absorbed on the kaolinite surface prevents weakly polar molecules from entering the kaolinite interlayers, which is probably the key reason that MeOH must be refreshed daily in the preparation of Kaol-Me compounds. After being treated with HCl to remove the impurities, Kaol-Me-HCl was successfully intercalated by cetyltrimethyl ammonium bromide and subsequently predominantly curled into nanoscrolls.

The Stability and Properties of Polystyrene/Kaolinite Nanocomposites during Synthesis via Emulsion Polymerization

The aim of this work was to study the stability and morphological properties of polystyrene latex containing kaolinite as a filler during the process of synthesis of nanocomposites viaemulsion polymerization. Nanocomposites with 1, 3, and 5 wt% of kaolinite were prepared. Latexes with 1 to 3 wt% of kaolinite were stable during the polymerization reaction. Hydrodynamic diameters of 93.68 and 82.11 nm were found for latexes with 1 and 3 wt% of kaolinite, respectively. The quantities of 1 to 3 wt% of kaolinite added during the reaction did not influence the reaction conversion curves or the number of particles. X-ray diffraction (XRD) and unconventional techniques of scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) showed the presence of exfoliated and intercalated structures of the kaolinite.