Synthesis, characterization, and electrocatalytic ability of γ-Fe2O3 nanoparticles for sensing acetaminophen

Maghemite (γ-Fe2O3) nanoparticles have been synthesized using co-precipitation method followed by chemically induced transition process. As prepared nanoparticles have been analyzed by X-ray diffraction, Raman and FTIR spectroscopies which reveal the γ-Fe2O3 phase. These γ-Fe2O3 nanoparticles have been used to modify the glassy carbon electrode (GCE) to form nano γ-Fe2O3 modified GC electrode for electrochemical sensing of acetaminophen (C6H9NO2) using potential controlled cyclic voltammetric (CV) technique. The obtained modified electrode shows an excellent electrocatalytic ability to sense acetaminophen in 0.1 M KCl supporting electrolyte. In addition, a significant enhancement in anodic peak current has been observed using nano γ-Fe2O3 modified GC electrode than the bare electrode. The CV plots reveal that redox peaks have been linearly co-related to the acetaminophen concentration in the range of 0.031 mM to 1 mM with sensitivity ~30.78 µA/mM

Electrochemical sensing of hydrogen peroxide based on nano γ-Fe2O3 modified glassy carbon electrode

Maghemite (γ-Fe2O3) nanoparticles were prepared using chemical synthesis method and used for sensing the hydrogen peroxide. The morphology of the γ-Fe2O3 nanoparticles was characterized by scanning electron microscopy. The γ-Fe2O3 nanoparticles were used to modify glassy carbon electrode (GCE) to form nano γ-Fe2O3 modified GC electrode for electrochemical sensing of hydrogen peroxide (H2O2). A potential controlled cyclic voltammetric (CV) technique was performed to sense hydrogen peroxide using nano γ-Fe2O3 modified GC electrode. The nano γ-Fe2O3 modified GC electrode showed excellent electrocatalytic ability towards H2O2 in 0.1M KCl supporting electrolyte. A significant enhancement in anodic peak current was observed for the nano γ-Fe2O3 modified GC electrode than those of bare electrode. The electrochemical characteristics of hydrogen peroxide on nano γ-Fe2O3 modified GC electrode  had been explored in this research communication

Electrochemical sensing of hydrogen peroxide based on nano γ-Fe2O3 modified glassy carbon electrode

162-166Maghemite (γ-Fe2O3) nanoparticles were prepared using chemical synthesis method and used for sensing the hydrogen peroxide. The morphology of the γ-Fe2O3 nanoparticles was characterized by scanning electron microscopy. The γ-Fe2O3 nanoparticles were used to modify glassy carbon electrode (GCE) to form nano γ-Fe2O3 modified GC electrode for electrochemical sensing of hydrogen peroxide (H2O2). A potential controlled cyclic voltammetric (CV) technique was performed to sense hydrogen peroxide using nano γ-Fe2O3 modified GC electrode. The nano γ-Fe2O3 modified GC electrode showed excellent electrocatalytic ability towards H2O2 in 0.1M KCl supporting electrolyte. A significant enhancement in anodic peak current was observed for the nano γ-Fe2O3 modified GC electrode than those of bare electrode. The electrochemical characteristics of hydrogen peroxide on nano γ-Fe2O3 modified GC electrode  had been explored in this research communication

Adsorption of Ni2+ and Cd2+ from Water by Calcium Alginate/Spent Coffee Grounds Composite Beads

The use of heavy metals in technological applications has led to detrimental effects on human health and the environment. Activated carbon and ion-exchange resins are commonly used to remove pollutants but they are expensive. Therefore, the research of low-cost alternatives derived from natural resources and organic wastes is being considered. The aim of this study considers the use of Calcium Alginate/Spent Coffee Grounds (CA–SCGs) composite beads to adsorb heavy metals from aqueous solutions, particularly, the removal of Ni2+ or Cd2+ at concentrations from 10 ppm to 100 ppm. CA–SCGs beads were made of equal proportions of alginate and spent coffee grounds and compared with calcium alginate beads (CA beads) and spent coffee grounds (SCGs) in terms of capacity and rate of adsorption. Three cycles of adsorption/desorption were done. The beads were characterized by Scanning Electron Microscopy coupled with an energy-dispersive X-ray spectroscopy (SEM–EDX), Fourier-transform infrared spectroscopy (FT–IR), Raman spectroscopy, and point of zero charge. Langmuir, Freundlich, and Sips models, and a pseudo-second-order kinetic equation were used. Sips model showed the best correlation with the adsorption of CA–SCGs beads with capacities of adsorption of 91.18 mg/g for cadmium and 20.96 mg/g for nickel. CA–SCGs beads had a greater adsorption than the CA beads, achieving adsorption percentages close to 100% than alginate alone, showing their effectiveness in heavy metal removal

Characterization of Recombinant His-Tag Protein Immobilized onto Functionalized Gold Nanoparticles

The recombinant polyhistidine-tagged hemoglobin I ((His)6-rHbI) from the bivalve Lucina pectinata is an ideal biocomponent for a hydrogen sulfide (H2S) biosensor due to its high affinity for H2S. In this work, we immobilized (His)6-rHbI over a surface modified with gold nanoparticles functionalized with 3-mercaptopropionic acid complexed with nickel ion. The attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the modified-gold electrode displays amide I and amide II bands characteristic of a primarily α-helix structure verifying the presence of (His)6-rHbI on the electrode surface. Also, X-ray photoelectron spectroscopy (XPS) results show a new peak after protein interaction corresponding to nitrogen and a calculated overlayer thickness of 5.3 nm. The functionality of the immobilized hemoprotein was established by direct current potential amperometry, using H2S as the analyte, validating its activity after immobilization. The current response to H2S concentrations was monitored over time giving a linear relationship from 30 to 700 nM with a corresponding sensitivity of 3.22 × 10−3 nA/nM. These results confirm that the analyzed gold nanostructured platform provides an efficient and strong link for polyhistidine-tag protein immobilization over gold and glassy carbon surfaces for a future biosensors development

Synthesis, characterization, and electrocatalytic ability of γ-Fe₂O₃ nanoparticles for sensing acetaminophen

722-728Maghemite (γ-Fe2O3) nanoparticles have been synthesized using co-precipitation method followed by chemically induced transition process. As prepared nanoparticles have been analyzed by X-ray diffraction, Raman and FTIR spectroscopies which reveal the γ-Fe2O3 phase. These γ-Fe2O3 nanoparticles have been used to modify the glassy carbon electrode (GCE) to form nano γ-Fe2O3 modified GC electrode for electrochemical sensing of acetaminophen (C6H9NO2) using potential controlled cyclic voltammetric (CV) technique. The obtained modified electrode shows an excellent electrocatalytic ability to sense acetaminophen in 0.1 M KCl supporting electrolyte. In addition, a significant enhancement in anodic peak current has been observed using nano γ-Fe2O3 modified GC electrode than the bare electrode. The CV plots reveal that redox peaks have been linearly co-related to the acetaminophen concentration in the range of 0.031 mM to 1 mM with sensitivity ~30.78 µA/mM

Removal of Copper from Water by Adsorption with Calcium-Alginate/Spent-Coffee-Grounds Composite Beads

Calcium Alginate/Spent-Coffee-Grounds composite beads (CA-SCGs beads), which were made of two different proportions of alginate and spent-coffee-grounds (3:3 and 3:10), respectively, were used to adsorb Cu2+ in aqueous solution. These beads were compared with calcium alginate beads (CA beads) and spent-coffee-grounds (SCGs) in terms of adsorption capacity and rate of adsorption. The experiments were carried out at an initial pH of 4 at 30 °C with initial concentrations of Cu2+ from 10 ppm to 100 ppm. Equilibrium data was fitted with Langmuir, Freundlich and Sips models, and a pseudo-second-order kinetic equation. The Sips model showed the best correlation with the experimental values. CA-SCGs (3:3) beads showed a faster adsorption rate versus the CA beads. Also, CA-SCGs (3:3) beads showed a larger capacity of adsorption according to the Sips model, but not in the Langmuir model. FT-IR spectra and SEM images were taken for characterization. This study has shown that the CA-SCGs (3:3) beads have a synergistic effect, combining the capacity of adsorption of CA beads with the kinetics of the SCGs. The CA-SCGs beads have proven to be an effective adsorbent of Cu2+. Therefore, they can provide a use for the SCGs; which are considered pollutants in landfills