Removal of sulfamethoxazole antibiotic from aqueous solutions by silver@reduced graphene oxide nanocomposite.

In the present study, the synthesizing of silver@reduced graphene oxide nanocomposite, through a facile precipitation method, is reported. In this method, in the synthesizing step, reduced graphene oxide was applied as a support, silver acetate as a precursor of Ag0, and sodium hydroxide as a medium for reducing procedure. Then synthesized particles were characterized by using transmission electron microscopy analysis, Fourier-transform infrared spectroscopy, field emission scanning microscopy/energy dispersive X-ray, and X-ray diffraction. Adsorbent potentials of the prepared nanocomposite were evaluated for sulfamethoxazole removal from polluted aqueous solutions via two different experimental methods, namely, "one-at-a-time" and "central composite design". The given results from the one-at-a-time method confirms that 0.007 g of silver@reduced graphene oxide nanocomposite can remove 88% (188.57 mg/g) of sulfamethoxazole from a 0.05 dm3 solution (initial concentration 30 mg/dm3) at pH = 5 after 3600 s' contact time. However, in the central composite design method, the optimum condition was 95% (79.17 mg/g) uptake of this drug from 0.05 dm3 of polluted solution with initial concentration of 30 mg/dm3 and pH = 7.5, using 0.018 g of the adsorbent in 3600 s. The main mechanism for sulfamethoxazole removal can be suggested as a suitable interaction between S atoms in functional groups in the drug and Ag atoms on the surface of nanoparticles. The pseudo-second-order patterns and Freundlich model described the empirical data isotherm and kinetics for the adsorption processes, respectively. The maximum adsorption capacity by experimental and theoretical isotherm methods (Langmuir) obtained 250 and 357 mg/g, respectively. Efficiency of the adsorbent in treatment of SMX from real samples displayed less hardness and electrical conductance samples have the maximum uptake percent while existence of nitrate ions in the solutions did not induce any negative effect on the removal of the SMX. All obtained results indicated loading of Ag nanoparticles on rGO nanosheets is an effective strategy for SMX uptake with high proficiency and shows great promise as pollutant adsorbent for environmental applications.

Silver@ graphene oxide nanocomposite: synthesize and application in removal of imidacloprid from contaminated waters.

Silver@graphene oxide nanocomposite was synthesized through an efficient approach, characterized by FTIR, EDX, and TEM instruments and then was used as adsorbent for imidacloprid removal from water in batch procedure. Effective variants such as contact time, pH, adsorbent dosage, and initial concentration of imidacloprid on procedure by two methods, one at a time and experimental design methods, were studied. Results in optimum conditions based on one at a time experiments is removal of 63% of the pesticide from 50 mL water containing 10 mg/L of imidacloprid by 0.03 g of the adsorbent at pH = 6.6 after 60 min while, experimental design method predict similarity results, 66% uptake of the poison by 0.06 g of the adsorbent in pH = 8. Kinetics and isotherm for adsorption processes follows Freundlich and pseudo-second-order models. Results confirm that Ag@graphene oxide nanocomposite can be applicable for removal of imidacloprid from real polluted water.