Functionalized Organosilica Materials for Nitrate Removal From Contaminated Water

ABSTRACT Elevated nitrate levels in surface and groundwater is a critical environmental problem, leading to devastating consequences for human health and natural ecosystems. This paper presents novel organosilica adsorbents that exhibit high efficiency in removing nitrates from contaminated water. Amino‐functionalized porous materials were synthesized via grafting and sol‐gel methods using various precursors. The sol–gel synthesis was carried out without tetraethoxysilane to increase the contents of amino groups, which act as adsorption sites for nitrate ions. Neither an acidic nor a basic catalyst was added to the reaction mixture. The sol–gel materials had higher contents of amino groups than the grafted ones (3.47–4.01 and 0.48–0.99 mmol/g, respectively). The amino groups were then converted to hydrochloride. It was found that even in the absence of a surfactant, the resulting material had a BET surface area of up to 217 m 2 /g, ensuring easy accessibility of surface amino groups for nitrate ions. The organosilica materials demonstrated excellent adsorption capacity for nitrate ions, which reached 3.68–4.04 mmol/g. These values exceed the corresponding literature data. The developed materials maintain high efficiency over a wide temperature range. They are recyclable and can be reused after regeneration. Biological testing confirmed significant inhibition of algae growth in contaminated water after treatment. The simplicity and environmental friendliness of production of these adsorbents using inexpensive and readily available chemicals, combined with their high adsorption efficiency, make them promising materials for removing nitrates from water to acceptable levels. Summary Effective organosilica adsorbents for removing nitrates from contaminated water were synthesized using an environmentally friendly method from inexpensive precursors. They demonstrated high adsorption capacity for nitrate ions, exceeding most published data under a wide range of conditions. The low cost of the developed materials and their recyclability suggest their potential for use in water purification.