A novel mesoporous Fe-silica aerogel composite with phenomenal adsorption capacity for malachite green

• Synthesis of low-cost mesoporous silica aerogel and Fe-silica aerogel composite by sol–gel method and ambient pressure drying method. • Iron doping could enhance the adsorption capacity of silica aerogel. • Novel maximum malachite green (MG) adsorption capacity of 1592 mg/g and 1250 mg/g for the aerogel composite and aerogel respectively. • Good reusable properties after 5 times ethanol-washing regeneration for both absorbents. Silica aerogel and Fe doped silica aerogel composite were synthesized by sol–gel method adopting ambient pressure drying method. The crystal structure, surface morphology, pore structure, surface functional groups and elemental composition of silica aerogel prepared with different concentrations of Fe 3+ were characterized by XRD, SEM, TEM, BET, FTIR, XPS and Zeta potential analysis. The specific surface area of the composite aerogel was found to decrease with the increase addition amount of FeCl 3 . The optimal composite aerogel adsorbent had a surface area of 240 m 2 /g with well-developed mesoporous network, which possessed a maximum malachite green(MG) adsorption capacity of 1592 mg/g, as compared to virgin silica aerogel of 1250 mg/g. Adsorption capacity for large molecules like MG is very low for the most popular adsorbent such as high surface area activated carbon, which is usually the first-choice adsorbent for wastewater treatment. Such high adsorption capacitiy of the silica aerogel composite is highly promising as it is on the classification of low-cost adsorbents, which can serve to be far better alternative for waste water treatment applications.