Nitrate removal study of synthesized nano γ-alumina and magnetite-alumina nanocomposite adsorbents prepared by various methods and precursors

Abstract

The challenges in water treatment include the need for efficient removal of pollutants like nitrate, which poses significant environmental and health risks. Alumina's significance lies in its proven effectiveness as an adsorbent for nitrate removal due to its high surface area and affinity for nitrate ions. This study delves into the synthesis of differen nano-sized γ-alumina (γA1-5) employing diverse precursors and methods, including nepheline syenite, lime, aluminum hydroxide, precipitation, and hydrothermal processes at varying reaction times. Simultaneously, magnetite (Fe3O4) nanoparticles and magnetite/γ-alumina nanocomposites (Fn/γA5) were synthesized using the co-precipitation method with varying weight ratios (n). Our primary objective was to optimize γ-alumina synthesis by comparing multiple methods, shedding light on the influence of different precursors and sources. Hence, a comprehensive adsorption study was conducted to assess the materials’ efficacy in nitrate removal. This study fills gaps in the literature, providing a novel perspective through the simultaneous assessment of magnetite/alumina nanocomposites and pure alumina performance. Structural and morphological properties were studied employing XRD, FT-IR, FESEM, EDX, XRD, and VSM techniques. The conducted experiments for γA5, F5/γA5, and F10/γA5 nanocomposites showcased the optimum pH of 5 and contact time of 45 min for all samples. The influence of nitrate’s initial concentration on the removal percentage was investigated with initial concentrations of 10 ppm, 50 ppm, and 100 ppm. γA5, F5/γA5 and F10/γA5 nanocomposites had 17.3%, 55%, and 70% at 10 ppm, 18%, 55.16%, and 74% at 50 ppm, and 8.6%, 53.1%, and 63%, respectively. The results highlighted that F10/γA5 can be used as a remarkable adsorbent for wastewater treatment purposes.