Enhancing the removal efficiency of azo dye using sodium borohydride in the presence of inorganic nano catalysts

• In this paper, two types of inorganic Nano oxides were prepared by the green synthesis method. These oxides were identified and their effectiveness was verified. • The decomposition of the azo dye solution RR120 was verified by NaBH 4 alone as well as in the presence of ZnO and Fe 3 O 4 . • The reducing agent is more effective in the presence of nanoparticles, while it takes longer to react with the dye solution in the absence of Nano catalysts. Synthetic dyes have gained great attention nowadays, especially the most popular azo dyes, due to their harmful and toxic effects on human health and the environment. Non-toxic zinc oxide and iron oxide nanoparticles (NPs) were prepared in a green way, which is fast, simple, low-cost, and environmentally friendly. XRD and FT-IR techniques were used to diagnose these NPs, the size of NPs ranges between (23–50) nanometers. It has been confirmed that the Reactive Red dye (RR120) has been removed from the nanoparticles' surface. Several experimental parameters were examined, such as temperature, reducing agent dosage, starting dye concentration, and medium acidity. According to the findings, the alkaline medium pH = 9 worked best for removing the dye using iron oxide in the presence of sodium borohydride, while the acidic medium pH = 3 worked best for removing the color using zinc oxide. At a contact period of 60 min, ZnO and Fe 3 O 4 shown a considerable impact on dye removal, achieving % 78 and % 52, respectively, while NaBH 4 by itself only managed % 37. After 15 min, the low dye concentration of 10 ppm produced ZnO and Fe 3 O 4 yields of % 80 and % 90, respectively, whereas the high dye concentration of 100 ppm produced % 30 and % 65 during the same contact period. The removal of dye increased from 33 % to 94 % at a contact period of 15 min when the temperature was adjusted from 298 to 323 k. During the same contact time, iron oxide obtained 70 % at 298 k, and the removal increased to 90 % at 323 k. Finally, the reducing agent functions optimally in the presence of nanoparticles, which offer a substantial surface area and an appropriate pathway for electrons to reach the dye. However, the absence of nanocatalysts results in a delayed dye reaction. This research work proposes a clean way to restore the environment from toxins and for a clean and elegant atmosphere.