Ultrasonic assisted synthesis of magnetic Ni-Ag bimetallic nanoparticles supported on reduced graphene oxide for sonochemical simultaneous removal of sunset yellow and tartrazine dyes by response surface optimization: Application of derivative spectrophotometry

• Published in: Ultrasonics sonochemistry 2019-01, Vol.50, p.239-250
• Main Authors: Mirzajani, Roya, Karimi, Somayeh
• Format: Article
• Language: English
• Subjects: Bimetallic nanoparticles; Box Behnken design; Derivative spectrophotometry; Graphene oxide; Sunset yellow; Tartrazine
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2018.09.022

•Simple and rapid simultaneous removal of sunset yellow and tartrazine from aqueous solution.•A magnetic Ni-Ag NPs@ rGO hybrid adsorbent can be fast and efficiently separated.•Utilizing the ultrasonic waves efficiently enhanced the removal of dyes from complex matrices.•A first-order derivative spectrophotometry was applied for monitoring of dyes residuals.•Application of RSM for modelling and optimization of variables affecting the removal process. The magnetic Ni-Ag bimetallic nanoparticles supported on reduced graphene oxide (Ni-Ag NPs/rGO) was synthesized and characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). Subsequently, this magnetic hybrid material as a novel adsorbent was applied for the sonochemical simultaneous removal of sunset yellow and tartrazine dyes in combination with first-order derivative spectrophotometric method to resolve the overlap between the spectra of these dyes. With magnetic properties, the adsorbent could easily be collected from aqueous solution using an external magnetic field. The parameters including initial concentration of each dye, adsorbent dosage and sonication time were studied by Box-Behnken design (BBD) and response surface methodology (RSM), while pH was studied by one-at-a-time approach. According to Box-Behnken design based on desirability function (DF), the best experimental conditions was set as initial sunset yellow concentration 10 mgL−1, initial tartrazine concentration 8.5 mgL−1, adsorbent dosage 0.045 g and sonication time of 15 min. The equilibrium data was fitted to different isotherm models and the results revealed the suitability of the Langmuir model. The maximum sorption capacity calculated from the Langmuir model was 28.57 and 26.31 mg g−1 for sunset yellow and tartrazine, respectively. Kinetic data revealed that the adsorption process followed a pseudo-second-order model. The reusability of the magnetite nanoparticles revealed about 8% decrease in the removal efficiency within four consecutive runs.