^aDepartment of Chemistry, College of Science and Arts, Qassim University,

Al-Rass 51921, Saudi Arabia

b Chemistry Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 13318, Saudi Arabia

cPhysics Department, College of Science, Imam Mohammad Ibn Saud Islamic

University (IMSIU), Riyadh 13318, Saudi Arabia

dDeanship of Scientific Research, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia

The work reported herein demonstrates the fabrication of CaO nanosheets employing a thermal decomposition method. The obtained CaO nanosheets were characterized using TEM, BET, XRD, EDX, and FTIR instruments. Moreover, the effect of initial dye concentration and pH on MB removal by CaO nanosheets was studied. The result showed that the nanoparticles have sizes around 100 nm, and the CaO nanosheets have an average diameter of 50 nm. Meanwhile, the average pore diameter and surface area of CaO are

15.847 Å and 5.881 m2. g_1, respectively. Numerical models based on Temkin, Freundlich, and Langmuir were applied to adsorption data to better understand the MB dye adsorption onto CaO nanoparticles. The sorption findings demonstrated a stronger fit with the Temkin model (R2 = 0.983) compared to the Freundlich model (R2 = 0.947) and Langmuir model (R2 = 0.968). The maximum adsorption capacity of MB on the CaO nanoparticles is 688.01 mg/g. The investigation determined that the adsorption kinetics adhered to the Pseudo-second-order kinetic model(R2=0.982).