Silica nanomaterials have gained significant attention in recent years due to their unique properties and potential applications in various fields such as electronics, catalysis, energy, and biomedicine. The silica nanomaterials exhibit a wide range of sizes and morphologies, including nanoparticles, nanospheres, nanorods, nanowires, and mesoporous structures. The size and morphology of silica nanostructures can be tailored by adjusting the synthesis parameters such as reaction time, temperature, and concentration of precursors. Thus, porosity of silica nanomaterials can be controlled by adjusting the synthesis parameters, such as the surfactant concentration in the sol–gel method (Li et al. in Adv Mater Interfaces 6:190042, 2019). Highly porous silica nanomaterials offer increased surface area and enhanced mass transport properties, enabling efficient adsorption or catalytic reactions. These silica-based nanomaterials, such as silica nanoparticles and mesoporous silica, have shown exceptional performance: heavy metal separation, organic pollutant removal, radioactive substance remediation, efficiency of silica nanomaterials in removing hazardous materials, organic pollutant removal, removal of organic dyes, kinetics of hazardous materials separation, etc. Therefore, the silica-based nanomaterials offer significant potential for addressing the challenges associated with wastewater separation and treatment. Their customizable properties, including size, morphology, and surface chemistry, allow for tailoring their performance to specific contaminants. By utilizing advanced fabrication methods and understanding their unique properties, silica-based nanomaterials can pave the way for efficient, cost-effective, and sustainable approaches to wastewater treatment.