نشریه پژوهش های شیمیایی و نانو مواد
پیاپی 1 (بهار 1401)

In the present study, determination of glucose was performed based on peroxidase-like activity of Fe3O4/CeO2/C-dot nanocomposite. In this way, a cascade reaction was used. At first, glucose in the presence of glucose oxidase enzyme reacts with oxygen to produce gluconic acid and H2O2. Then, in the second step, H2O2 in the presence of Fe3O4/CeO2/C-dot converts TMB (3,3’,5,5’- tetramethylbenzidine) to oxTMB which causes the solution to turn blue. Intensity of blue color depends on glucose concentration, nanocomposite amount, TMB concentration and solution pH. Absorbance of solution at 650 nm was increased by increasing the glucose concentration. So, linear range between glucose concentration and intensity of absorbance at 650 nm was observed. Experimental detection limit for glucose detection was obtained as 1×10-5 M. Also, the sensing system shows high selectivity towards the detection of glucose in the presence of fructose, lactose and maltose as interferences.

  A new heterogeneous sulfonated magnetic nanocatalyst decorated with hydrophobic tag denoted as hydrophobic-NBS-γ-Fe2O3, is successfully synthesized and characterized by different methods such as FT-IR, SEM, TEM, TGA and elemental analysis. The catalyst worked well for the efficient synthesis of hexahydroquinolines (HHQs) via the Hantzsch one-pot four-component reactions under solvent-free conditions. The enhanced catalytic activity of hydrophobic-NBS-γ-Fe2O3 could be attributed to the synergistic effects of the anchored sulfonic acid groups and hydrophobic tags on the catalyst surface. The presence of hydrophobic tags well circumvents the problem of water-poisoning of acidic sites in the synthesis of HHQs as a water generating reaction and also facilitates the mass transfer of hydrophobic starting materials to the active acidic sites of the catalyst. Using the solvent-free conditions, good to high yields of the products, use of reusable catalyst, short reaction times and simple work-up procedure make this method favorable from the environmental and economic viewpoints for the synthesis of HHQs. This study represents the first example of using a hydrophobic sulfonated magnetic nanocatalyst towards the one-pot four-component synthesis of HHQs.

Recently adsorption by using of modified nano-adsorbents as one of the methods of separating heavy metals from wastewater has been attracted a lot of attention due to the simplicity and high efficiency of the process. In this work, at first a graphene-oxide-based magnetic nanostructure modified by tryptophan was synthesized. The synthesized magnetic graphene oxide has a high absorption capacity for Cu(II) ion (i.e., 118 mg g-1) due to the presence of nitrogen groups of tryptophan exist on the surface of adsorbent. Kinetic parameters and contact time were optimized, and the results showed that the optimal contact time is 60 minutes. Absorption kinetic studies were performed using pseudo-first-order and pseudo-second-order models. The findings indicated that the pseudo-second-order model with a higher regression coefficient (R2=0.9978), compared to the pseudo-first-order model (R2=0.9942), describes the test data better. The adsorption kinetics’ adherence to the pseudo-second-order model demonstrated that the rate-determining step is a chemical interaction. In order to investigate the thermodynamics of absorption, the effects of temperature on the absorption process were explored by using of Van’t Hoff equations, and the results showed that the absorption process is endothermic.