Maryam Ghasemi; Javad Azimi-Amin
Abstract
Here, graphene oxide was synthesized and reduced by lemon extract (source of vitamin C) in an aqueous solution under different pH (3 and 10). The lemon extract was prepared using a solvent-free method. The proposed mechanisms for the reduction of GO may be due to the nucleophilic attack of oxygen anion ...
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Here, graphene oxide was synthesized and reduced by lemon extract (source of vitamin C) in an aqueous solution under different pH (3 and 10). The lemon extract was prepared using a solvent-free method. The proposed mechanisms for the reduction of GO may be due to the nucleophilic attack of oxygen anion of ascorbic acid to the epoxy or hydroxyl groups of GO sheets. Based on Raman spectra, with increasing the solution pH, the repair of the graphitic sp2 domain of the RGOs decreased. Reduced graphene oxide was successfully used to synthesize Fe3O4/RGO nanocomposite and remove Pb ions from aqueous media. The obtained Fe3O4/RGO nanocomposite was characterized by XRD, FTIR, SEM, and BET analysis. Based on these characterization techniques, reduced graphene oxide is distinguishably coated by Fe3O4 nanoparticles. The effect of different parameters: contact time (1-60 min), initial lead concentration (25-200 mg/L), adsorbent dosage (0.01-0.07 g), and the solution’s initial pH (1-8) on the removal of lead ions was studied using batch-scale tests. The maximum lead ion removal was achieved up to 90 % for Pb ions, respectively at optimum operating conditions viz. pH 5, Pb initial concentration 100 mg/L, Fe3O4/RGO dose 0.05 g, and contact time 30 min. Obtained results showed that the maximum adsorption capacity of Fe3O4/RGO for lead ion was 107.52 mg/g within 60 min of contact time. The adsorption behavior can be well described with the Langmuir isotherm and the pseudo-second-order models, indicating that the adsorption process was a monolayer and chemisorption adsorption.
Maryam Ghasemi; Somaye Mashhadi; Javad Azimi-Amin
Abstract
In this study, we have synthesized a new Fe3O4/AC nanocomposite using low cost adsorbent by microwave assisted in situ co-precipitation technique that was used as an effective adsorbent for the removal of methylene blue (MB) using the Taguchi design method as an optimization strategy. The optimum parameters ...
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In this study, we have synthesized a new Fe3O4/AC nanocomposite using low cost adsorbent by microwave assisted in situ co-precipitation technique that was used as an effective adsorbent for the removal of methylene blue (MB) using the Taguchi design method as an optimization strategy. The optimum parameters are pH 7, Fe3O4/AC nanocomposite dose 0.03 g, contact time 30 min, initial concentration of MB 25 mg/L and temperature 298 K. The obtained results of ANOVA show that their percent contribution in descending order is pH (66.81%) > adsorbent dose (25.54%) > temperature (4.83%) > initial MB concentration (1.23%) > contact time (0.32%). The kinetic data were fitted to the pseudo-first-order, pseudo-second-order and intra-particle diffusion models and adsorption of MB dye followed pseudo-second-order kinetic. The obtained values of regression coefficient for Langmuir (0.98), Frendluich (0.93) and Dubinin–Radushkevich (0.94) showed that adsorption process fits to the Langmuir isotherm and the maximum adsorption capacity is 384.6 mg/g. Moreover, the thermodynamics studies suggested the spontaneous nature of adsorption process.