Abstract

Aromatic amines such as 4-nitroaniline (4-NA) are commonly released into the environment by wastewaters containing azo colors. In the present study, silver nanoparticles were synthesized using the extract of Damask rose. Then, its physicochemical properties were determined. The effects of parameters such as pH, contact time, persulfate (PS) concentration, and nanosilver (NS) concentration on 4-NA removal were studied by a cylindrical reactor placed in ultrasound (US) device. The results showed that the efficiency of 4-NA removal by the US/PS/NS process increased with increasing the dose of NS and PS, as well as the contact time. pH had no significant effect on the removal efficiency even though in acidic pHs the removal efficiency was 5 higher. Also, over time, the pH of the reactor decreased due to the reactions occurring; this caused the same efficiency at different pHs. In the US/PS/NS process, increasing the initial 4-NA concentration also reduced the efficiency slightly. Under the optimal conditions, including pH = 5, contact time = 90 min, US power = 60 W, NS concentration = 300 mg/L, and PS concentration = 1.68 mM, the US/PS/NS process could reduce 4-NA up to 93.