Despite the significant advancements in wastewater treatment technologies, the field still lacks a comprehensive synthesis of recent developments in heavy metal removal using functionalized mesoporous silica materials. Adsorption has emerged as a preferred method due to its versatility, efficiency, and cost-effectiveness. Mesoporous silica stands out as a leading adsorbent due to its porous structure and surface modification potential, yet there remains a critical need to systematically analyze and evaluate recent innovations in this rapidly evolving field. This review addresses this knowledge gap by consolidating and critically analyzing the recent literature on functionalized mesoporous silica for heavy metal ion removal from wastewater. Through a detailed examination of the maximum adsorption efficiencies of organically modified mesoporous silica-based materials for various metal ions, with particular emphasis on recent trends in removing heavy metal ions, this work provides a crucial foundation for understanding current capabilities and limitations. Additionally, by identifying patterns in synthesis methods, surface functionalization strategies, and performance metrics across different studies, this review offers valuable insights into optimization opportunities and unexplored research directions. The systematic compilation and analysis of these data will serve as an essential resource for researchers working to advance the design and application of modified mesoporous silica for diverse water pollutant removal applications.

MCM-41 and non-ordered mesoporous silica were modified using hexamethyl-disilazane (HMDS). The hydrophobic and hydrophilic properties of grafted materials were studied and compared to a purely all silica BEA zeolite by using competitive and noncompetitive water toluene adsorption. A linear correlation between the silylation degree and the hydrophobicity measurements has been found for MCM-41 materials. Even if highly silylated MCM-41 material have more hydrophilic sites (silanol groups) than all silica zeolite, water molecule condensation is not observed because these sites are isolated. Thus, the highly silylated MCM-41 sample exhibits not only hydrophobicity 2.3 times higher than all silica BEA zeolite but also possesses a storage capacity for toluene and chlorobenzene 3 times higher than this zeolite. In competition with water, the organic molecule (toluene or chlorobenzene) adsorption is always favored even if water adsorption is enhanced by chlorobenzene polarity.

The heavy metals removal efficiency of synthetic NaX zeolite has been studied. The sorbent was fully characterized by nitrogen sorption, X-ray diffraction, FT-IR and scanning electron microscopy. The batch sorption tests were performed taking into consideration several factors such as m/V ratio, contact time, pH and initial metal ions concentration. The maximum sorption capacities were 3.45, 3.86 and 4 mmol g⁻¹ for Pb²⁺, Cd²⁺ and Cu²⁺, respectively. Fixed-bed experiments were carried out to test the applicability of NaX zeolite as well as column regeneration experiments.

H-ZSM-5 and H-*BEA zeolites were hydrothermally synthesized with different Si/Al ratios (∼12 to ∼40). The physico-chemical properties of the resulting materials were fully characterized by several techniques (NMR, BET, PXRD, and pyridine thermal desorption followed by infrared spectroscopy). To assess the effect of the zeolite type and Si/Al ratio on sample reactivity, the charge separation processes between the zeolite framework and the adsorbed trans-stilbene (t-St) molecule were investigated by UV-visible diffuse reflectance and FT-Raman spectroscopy. The UV-visible absorption spectra obtained after t-St adsorption show a clear difference depending on the zeolite type. It appears that the radical cation resulting from t-St spontaneous ionization is more stabilized in the MFI-type framework than in the *BEA topology. However, the amount and stability of the electron–hole pair resulting from the radical cation evolution to a charge transfer complex are more important in the *BEA zeolite. On the basis of the experimental results and physico-chemical properties of the sample, we found that the radical cation and the electron–hole stabilities are strongly dependent on the amount of hexacoordinated aluminum (Al^(VI)) and more precisely on their environment, i.e. the distance between Brønsted sites and strong Lewis sites or Brønsted Strong Lewis Pairs (BSLPs).