Adsorptive removal of hexavalent molybdenum from water using diatomite based termite mound composite: Box–Behnken design optimization

The objective of the study is to use the diatomite-based termite mound composite to remove Mo (VI) from water. The study evaluated the properties of an adsorbent through various tests such as pHpzc, XRF, XRD, FTIR, SEM, TGA, DSC, and BET. The adsorbate was analyzed using an ICP-OES 8100 after filtration through a 0.45 μm filter. A Response Surface Methodology (RSM) with Box–Behnken Design (BBD) was applied to optimize the removal of hexavalent molybdenum (Mo (VI)). The study characterizes an adsorbent composed of finely divided particles, revealing through SEM images the mineral distribution, which includes quartz (Qz), muscovite (Ms), and anatase (Ant). ANOVA is employed to assess the RSM results for optimal conditions. The study found a significant correlation (P < 0.05) between projected and experimental values for Mo (VI) adsorption using a quadratic model. The adsorption followed the linear Langmuir (R2 = 96.15%) and the non-linear Temkin isotherm (R2 = 91.78%) models and non-linear pseudo-second-order kinetic models (R2 = 99.73%), with a maximum capacity of 12.83 mg/g. Thermodynamic analysis (ΔH0, ΔS0, and ΔG0) revealed that the process was endothermic and spontaneous. Thus, the diatomite-modified termite mound composite (DMTM (2:3)) is an effective adsorbent for Mo (VI) removal from water.