Abstract
BackgroundMagnetic graphene oxide (Fe3O4@SiO2-GO) nanocomposite was fabricated through a facile process and its application as an excellent adsorbent for lead (II) removal was also demonstrated by applying response surface methodology (RSM).MethodsFe3O4@SiO2-GO nanocomposite was synthesized and characterized properly. The effects of four independent variables, initial pH of solution (3.5–8.5), nanocomposite dosage (1–60 mg L−1), contact time (2–30 min), and initial lead (II) ion concentration (0.5–5 mg L−1) on the lead (II) removal efficiency were investigated and the process was optimized using RSM. Using central composite design (CCD), 44 experiments were carried out and the process response was modeled using a quadratic equation as function of the variables.ResultsThe optimum values of the variables were found to be 6.9, 30.5 mg L−1, 16 min, and 2.49 mg L−1 for pH, adsorbent dosage, contact time, and lead (II) initial concentration, respectively. The amount of adsorbed lead (II) after 16 min was recorded as high as 505.81 mg g−1 for 90 mg L−1 initial lead (II) ion concentration. The Sips isotherm was found to provide a good fit with the adsorption data (KS = 256 L mg−1, nS = 0.57, qm = 598.4 mg g−1, and R2 = 0.984). The mean free energy Eads was 9.901 kJ/mol which confirmed the chemisorption mechanism. The kinetic study determined an appropriate compliance of experimental data with the double exponential kinetic model (R2 = 0.982).ConclusionsQuadratic and reduced models were examined to correlate the variables with the removal efficiency of Fe3O4@SiO2-GO. According to the analysis of variance, the most influential factors were identified as pH and contact time. At the optimum condition, the adsorption yield was achieved up to nearly 100 %.
Highlights
Magnetic graphene oxide (Fe3O4@SiO2-Graphene oxide (GO)) nanocomposite was fabricated through a facile process and its application as an excellent adsorbent for lead (II) removal was demonstrated by applying response surface methodology (RSM)
Characterization of GO-Fe3O4 nanocomposite As shown in Fig. 2, a UV- visible spectrum obtained for the GO aqueous dispersion displays a plasmon peak at 231 nm which is related to the π → π* transitions due to the aromatic C − C bonds
Adding the lead ( )׀׀aqueous ions into the GO dispersion resulted in producing a growing humpy pattern around 300 nm which can be attributed to the affinity between lead ( )׀׀and C = O bonds relating to the carboxylic groups in the GO structure [33]
Summary
Magnetic graphene oxide (Fe3O4@SiO2-GO) nanocomposite was fabricated through a facile process and its application as an excellent adsorbent for lead (II) removal was demonstrated by applying response surface methodology (RSM). Many processes such as precipitation, membrane filtration, adsorption, and ion exchange have been applied to remove lead ( )׀׀and other toxic metals from the industrial effluents [5]. A few methods such as using functionalized adsorbents and membrane technologies can be adopted to capture low concentrations around 1 mg L−1, which is commonly occurred in drinking water sources [6]. Adsorption processes are Khazaei et al Journal of Environmental Health Science & Engineering (2016) 14:2 useful in removal low concentrations of metal ions from aqueous solutions, but there are two main limitations regarding to the use of them; 1. The GO flake surface contains different functional groups including epoxide and hydroxide, whereas, the edge of flakes are mainly contained a hedge of carboxylic groups [14]
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