Synthesis of Dendritic Magnetic Graphene Oxide By Radical Polymerization As Adsorbent For Rapid Removal of Malachite Green From Aqueous Solutions

Disposal of Malachite green containing sewage from related industries has resulted in global concern. Thus, removing Malachite green from aqueous solutions is highly significant and necessary. during this study, magnetic graphene oxide coated with dendrimer (G (1) -MGO-chitosan) was prepared successfully and applied for removing cationic malachite green in various conditions. The properties of the synthesized adsorbent (G (1) -MGO-chitosan) were evaluated using XRD, FTIR, BET, FESEM, TEM and TGA. Furthermore, the effect of different parameters on malachite green removal was studied. The results indicated that at pH = 8, temperature of 40 °C, initial concentration 600 µg mL-1 and contact time 10 min were obtained as optimal values for removing malachite green with nanoadsorbent (G (1) -MGO-chitosan) with maximum adsorption capacity of malachite green was obtained at 38.71 µg mg-1. The high correlation coefficient (R2 = 0.9947) for the Freundlich model confirmed that the Freundlich model is appropriate for fitting laboratory data. Based on the model, Temkin heat adsorption for malachite green j mol-1 is B = 8.1447, indicating that the process of dye adsorption with Nano adsorbent is of physical type. Based on the results of fitting the kinetic models of Malachite green adsorption by Nano adsorbent, Hu and McKay’s model with higher correlation coefficient (R2 = 0.9994) is more consistent with experimental data than other models. Since no large decrease is observed in Malachite green removal in seven consecutive recovery cycles, thus Nano adsorbent has a high stability and can be used several times.

Modification of Magnetic Graphene Oxide By An Earth-Friendly Deep Eutectic Solvent To Preconcentrate Ultratrace Amounts Pb(II) In Oil Seeds

The aim of this article is presenting an earth-friendly deep eutectic solvent (DES) to preconcentrate ultratrace amounts of Pb(II) prior to its quantification by flame atomic adsorption spectroscopy. The synthesis of adsorbent started by preparing graphene oxide according to the modified Hammer’s method, followed by magnetization by Fe3O4 nanohemispheres. Magnetic graphene oxide was dispersed in a mixture of LiCl and urea at 60° via ultrasonication. All the materials are environmentally-friendly and the preparation strategy is energy efficient. X-ray diffraction, scanning electron microscopy, alternating gradient force magnetometer and Fourier-transform infrared spectroscopy were applied to characterize the products. Graphene oxide has a large surface area and could be functionalized with DESs through π-π interaction and electrostatic force. Urea has active negative sites, which garb heavy metals due to the interaction between negative and positive agents. Accordingly, this adsorbent (UreaLiCl-mGO) could be offered as a capable adsorbent to preconcentrate ultratrace amounts of Pb(II). Conditions were optimized, and under the optimum situation, (a) limit of detection of 99 × 10-8 g L-1, (b) relative standard deviation (n=5) of 1.3%, (c) preconcentration factor of 100 (d) linearity of dynamic range of 5.0 × 10-6 – 23 × 10-6 g L-1, (e) durability of 6 months and (f) reusability of 7 times prove applicability of the adsorbent. The tests of selectivity, effect of interference ions, swelling property, isotherm of adsorption, kinetic of adsorption and thermodynamic of adsorption were completely investigated. Four different oil seeds were successfully applied as real samples.