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.
Sedigeh Sabalanvand; Hossein Hazrati; abbas jafarizad; Yoones Jafarzadeh
Abstract
Many studies have been done to reduce the membrane fouling and to increase the quality of the effluent from membrane bioreactor (MBR). One of the most important researches in this filed is the use of adsorbents and nanoparticles in the biological system. In this study, the effects of Fe3O4 nanoparticles ...
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Many studies have been done to reduce the membrane fouling and to increase the quality of the effluent from membrane bioreactor (MBR). One of the most important researches in this filed is the use of adsorbents and nanoparticles in the biological system. In this study, the effects of Fe3O4 nanoparticles were investigated using COD, extracellular polymeric substances (EPS), soluble microbial products (SMP), flux, particle size distribution (PSD) and FTIR analysis. The COD test showed that the removal rate was 86.92% in MBR without Fe3O4 (R1) and 98.17% in MBR with Fe3O4 (R2). The amount of EPS and SMP in the reactor containing nanoparticles is lower than that of a non-nanoparticle reactor. Flux rate is higher in R2, so it can be said that the presence of nanoparticles has a positive effect of reducing the membrane fouling. Also, FTIR analysis showed that the amount of protein in the biologic system R2, which is the major membrane contaminant, is greater than R1.