Performance Research of the natural sand grains for adsorption enrichment and removal of Cd(II) from aqueous solution

This study investigates the performance of natural sand particles from the Taklamakan Desert as a low-cost adsorbent for removing Cd(II) from water. SEM, FTIR, and XRD characterization revealed a multi-porous silica structure with abundant Si–OH and Si–O–Si groups. Using a microcolumn coupled with FAAS under optimal conditions (pH 5.5–6.5, flow rate 3 mL·min ^− 1 , room temperature), the sand particles exhibited a dynamic saturation adsorption capacity of 10.2 mg·g ^− 1 for Cd(II) ions, achieving an adsorption rate of 90.2%. Equilibrium data conformed to the Freundlich model (R ²  = 0.938), indicating heterogeneous multilayer adsorption. Kinetic data followed pseudo-second-order kinetics (R ²  = 0.966), revealing a chemically controlled mechanism. Thermodynamic analysis confirmed the process as a spontaneous, endothermic reaction. After desorption using 0.01 mol·L ^− 1 hydrochloric acid, the desorption rate reached 98.4% with no significant loss of adsorption capacity. This demonstrates that natural sand particles represent a sustainable and highly efficient adsorbent for Cd(II) remediation.