Document Type : Article
Authors
Faculty of Civil and Environmental Engineering Tarbiat Modares University
Abstract
According to studies, nearly 15 percent of synthetic dyes enter wastewater during production and consumption operations annually, which is very dangerous and causes many problems for the environment. Thus, removing these compounds is mandatory. NZVI can be used in detoxification of many environmental pollutants, as a reducing agent and catalyst. In order to develop the technology of NZVI, bimetallic nanoparticles are prepared by deposition of a noble metal, such as nickel, over iron nanoparticles. In this study, as a simple and applicable method in the laboratory, bimetallic nanoparticles, Fe-Ni, were made using the method of chemical deposition of iron chloride ({$FeCl_3$}.{$6H_{2}O$})by a strong reducer, sodium bohr hydride (NaBH4), under nitrogen gas. To ensure the size and nature of the nanoparticles, SEM and XRD experiments were performed. Then, the nanoparticles were used in a slurry system to remove the azo dye (ccid red 14). To achieve optimum conditions during the experiments,
the parameters of the dye initial concentration, nanoparticle dosage, pH, elapsed time from creation to implementation of the nanoparticles, shaking speed and temperature were investigated. Then, to identify other effective factors, a control experiment was performed under the optimal conditions and it was found that ethanol, nickel, and light do not have any effect on dye removal. The reducer, however, was able to remove the dye completely. Also, the use of nickel with 3 wt\% iron increased dye removal efficiency by 14.65\%. According to the survey conducted, optimal conditions were obtained when the tests were performed at temperatures of \ {$25\pm2 ^0C$} \ with newly synthesized nanoparticles that have 0.05 gr/L concentration with an initial concentration of dye equal to 200 mg/L and pH of 7.5 and a beginning mixer time of two minutes. These nanoparticles had very high activity, so, removal efficiency after 2, 30 and 240 minutes, was 79.39, 90.52 and 94.42 percent, respectively. Finally, LC-Mass experiments indicated that after 4 hours of reaction, the azo band in the dye was broken.
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