Advances in Nanochemistry
Volume:3 Issue: 2, Winter and Spring 2021

Herein, a carbon ionic liquid electrode (CILE) incorporated with Cu2+ ion-imprinted polymeric nanoparticles is explored for the voltammetric determination of Cu2+ ions. The procedure is based on the interfacial preconcentration of Cu2+ on an imprinted polymer modified CILE through the surface coordination effect. The modified electrode exhibited a significantly increased sensitivity and selectivity for Cu2+ compared with the non-modified electrode. The effects of various parameters, such as the amount of ionic liquid, graphite and, IIP nanoparticles, the effect of Cu2+ extraction conditions on the electrode response, the accumulation potential and the accumulation time were investigated. The modified electrode showed a linear voltammetric responses to Cu2+ in the ranges of 25-1250 nM with a limit of detection (LOD) of 9.4 nM (S/N =3). The interference experiments showed that Cu2+ signal was not interfered in the presence of some potential interfering ions and organic species. Moreover, this electrode presented the high sensitivity and excellent selectivity compared with previously reported methods in the area of electrochemical detection of Cu2+. These results demonstrate the feasibility of using the prepared Cu2+-imprinted polymer/CILE for efficient determination of Cu2+ in water samples.

In this work, the modified carbon paste electrode was prepared by the nano-sized magnetic molecularly imprinted polymer (MMIP) and utilized for electrochemical determination of valproic acid. The synthesized nano-MMIP was characterized by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR). The resulted nano-sized compound was suspended in 0.1 M HCl and then collected on the surface of a carbon paste electrode via a permanent magnet, which was situated within the carbon paste electrode. The electrochemical performance of the valproic acid sensor was investigated by cyclic voltammetry and differential pulse voltammetry techniques. All parameters influencing the electrode performance, including pH, the amount of MMIP, and the immersion time, were evaluated and optimized. Under the optimal condition, the sensor showed a dynamic linear concentration range of 0.5 nM–150.0 µM with a detection limit of 0.16 nM.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in our environment and their importance appears from their toxicity and carcinogenicity to humans. Water can become contaminated with PAHs from different sources such as runoff in urban areas, wastewater from specific industries, and petroleum spills. Herein, an efficient turn-on fluorescence sensor, based on covalently-linked glutathione (GSH)-capped CdTe/ZnS core/shell quantum dot (QDs)–graphene oxide (GO) nanocomposite was developed for PAHs sensing. The fluorescence emission of the QDs–GO nanocomposite was increased relative to the unconjugated QDs. Various techniques including TEM, SEM, XRD, FT-IR, UV/Vis, and fluorescence spectrophotometry were employed to characterize the QDs and the QDs–GO nanocomposite. Naphthalene, as a model of PAHS, was selected for further studies as the fluorescence enhancement. A limit of detection (LOD) of 7.71 × 10-8 mol L-1 was obtained for naphthalene under optimum conditions.

The hydrophobicity of the surface of polyethersulfone causes negative effects on membrane performance. One of the applicable and suitable methods to improve the performance of the polymeric membrane is the addition of nanoparticles. Here, copper oxide nanoparticles (Cu2O NPs) were used to modify the surface of the membrane. Nanofiltration membrane based on polyethersulfone polymer was prepared by dimethylacetamide as a solvent, polyethylene glycol as pore-maker, and Cu2O NPs as a modifier of the membrane properties, using the reverse-phase technique. The membranes were structurally studied by FTIR, SEM, EDX, AFM techniques. Results have shown that the membranes with different concentrations of nanoparticles perform differently. Modified membranes with higher amounts of Cu2O NPs showed improved pure water flux, porosity, and antifouling property due to increased hydrophilicity. The modified membrane containing 0.5 wt.% Cu2O showed the best results. In higher concentrations like 1 wt.%, the agglomeration of nanoparticles fills the pores, reduces the porosity, and decreases the flux. Nanofiltration performance was also examined by removal of hydroquinone.

Dye and textile industries are suffering from pollutant issues from industrial wastewater. Due to attempts made by textile industries for producing diverse products, using different chemical compounds, especially new dyes, and creating complex wastewater are unavoidable. To date, various physical and chemical processes such as chemical precipitation, adsorption, electrocoagulation, etc. were used to treat relevant wastewater. Physicochemical systems such as surface adsorption have attained many interests, due to the unique physical and chemical properties of these nanoparticles compared to the balk type. Among different nanomaterials, magnetic nanomaterials were received the highest interest due to the facile separation by an external magnetic field and their high capacity.  Iron oxide nanoparticles, specially super-magnetic or magnetic Fe3O4 nanoparticles, have the highest usage. Considering the specific properties of magnetic MOF, the physical and structural features of the synthesized adsorbent were investigated by BET, XRD, FTIR, SEM, and TEM techniques. The effect of different parameters such as pH, the concentration of erythrosine B dye, adsorbent weight, contact time, and the temperature was studied to determine the thermodynamic parameters, equilibrium isotherms, kinetic of the adsorption process, and finally their application on the adsorption of erythrosine B dye.

The electrochemical oxidation of an antidepressants drug, trazodon (TRZ) on the modified titanium dioxide–carboxylated multiwall carbon nanotube glassy carbon electrode (TiO2-cMWCNTs/GCE) was studied. The TiO2-cMWCNTs/GCE sensor was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The influence of the effective parameters on the electrochemical behavior of TRZ such as: pH, modifier volume, accumulation potential and time were optimized. Under the optimized conditions, the proposed sensor was applied to determine TRZ  in the ranges of 6–100 nM and 100-1000 nM with the detection limit of 5 nM using  differential pulse anodic stripping voltammetry (DPASV) at neutral pH. The modified electrode exhibited a good sensitivity, stability and pleasant reproducibility, which was also applied for the determination of TRZ in the spiked human serum and pharmaceutical formulations, with satisfactory results.