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A novel MnO2 nanoparticles/chitosan-modified pencil graphite electrode (MnO2 NPs/CS/PGE) was constructed using two different MnO2 polymorphs (g-MnO2 and 3-MnO2 nanoparticles). X-ray single phases of these two polymorphs were obtained by the comproportionation reaction between MnCl2 and KMnO4 (molar ratio of 5 : 1). The temperature of this reaction is the key factor governing the formation of the two polymorphs. Their structures were confirmed by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) and energy dispersive X-ray (EDX) analysis. Scanning electron microscopy (SEM)was employed to investigate the morphological shape of MnO2 NPs and the surface of the bare and modified electrodes. Moreover, cyclic voltammetry and electrochemical impedance spectroscopy (EIS)were used for surface analysis of the modified electrodes. Compared to bare PGE, MnO2 NPs/CS/PGE
shows higher effective surface area and excellent electrocatalytic activity towards the oxidation of the standard K3[Fe(CN)6]. The influence of different suspending solvents on the electrocatalytic activity of MnO2 was studied in detail. It was found that tetrahydrofuran (THF) is the optimum suspending solvent regarding the peak current signal and electrode kinetics. The results reveal that the modified g-MnO2/ CS/PGE is the most sensitive one compared to the other modified electrodes under investigation. The modified g-MnO2/CS/PGE was applied for selective and sensitive determination of FUR. Under the optimized experimental conditions, g-MnO2/CS/PGE provides a linear response over the concentration range of 0.05 to 4.20 mmol L-1 FUR with a low limit of detection, which was found to be 4.44 nmol L-1 (1.47 ng mL-1) for the 1st peak and 3.88 nmol L-1 (1.28 ng mL-1) for the 2nd one. The fabricated sensor exhibits a good reproducibility and selectivity and was applied successfully for the determination of FUR in its dosage forms and in spiked urine samples with good accuracy and precision.

A novel MnO2 nanoparticles/chitosan-modified pencil graphite electrode (MnO2 NPs/CS/PGE) was constructed using two different MnO2 polymorphs (g-MnO2 and 3-MnO2 nanoparticles). X-ray single phases of these two polymorphs were obtained by the comproportionation reaction between MnCl2 and KMnO4 (molar ratio of 5 : 1). The temperature of this reaction is the key factor governing the formation of the two polymorphs. Their structures were confirmed by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) and energy dispersive X-ray (EDX) analysis. Scanning electron microscopy (SEM)was employed to investigate the morphological shape of MnO2 NPs and the surface of the bare and modified electrodes. Moreover, cyclic voltammetry and electrochemical impedance spectroscopy (EIS)were used for surface analysis of the modified electrodes. Compared to bare PGE, MnO2 NPs/CS/PGE
shows higher effective surface area and excellent electrocatalytic activity towards the oxidation of the standard K3[Fe(CN)6]. The influence of different suspending solvents on the electrocatalytic activity of MnO2 was studied in detail. It was found that tetrahydrofuran (THF) is the optimum suspending solvent regarding the peak current signal and electrode kinetics. The results reveal that the modified g-MnO2/ CS/PGE is the most sensitive one compared to the other modified electrodes under investigation. The modified g-MnO2/CS/PGE was applied for selective and sensitive determination of FUR. Under the optimized experimental conditions, g-MnO2/CS/PGE provides a linear response over the concentration range of 0.05 to 4.20 mmol L-1 FUR with a low limit of detection, which was found to be 4.44 nmol L-1 (1.47 ng mL-1) for the 1st peak and 3.88 nmol L-1 (1.28 ng mL-1) for the 2nd one. The fabricated sensor exhibits a good reproducibility and selectivity and was applied successfully for the determination of FUR in its dosage forms and in spiked urine samples with good accuracy and precision.

A novel MnO2 nanoparticles/chitosan-modified pencil graphite electrode (MnO2 NPs/CS/PGE) was constructed using two different MnO2 polymorphs (g-MnO2 and 3-MnO2 nanoparticles). X-ray single phases of these two polymorphs were obtained by the comproportionation reaction between MnCl2 and KMnO4 (molar ratio of 5 : 1). The temperature of this reaction is the key factor governing the formation of the two polymorphs. Their structures were confirmed by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) and energy dispersive X-ray (EDX) analysis. Scanning electron microscopy (SEM)was employed to investigate the morphological shape of MnO2 NPs and the surface of the bare and modified electrodes. Moreover, cyclic voltammetry and electrochemical impedance spectroscopy (EIS)were used for surface analysis of the modified electrodes. Compared to bare PGE, MnO2 NPs/CS/PGE
shows higher effective surface area and excellent electrocatalytic activity towards the oxidation of the standard K3[Fe(CN)6]. The influence of different suspending solvents on the electrocatalytic activity of MnO2 was studied in detail. It was found that tetrahydrofuran (THF) is the optimum suspending solvent regarding the peak current signal and electrode kinetics. The results reveal that the modified g-MnO2/ CS/PGE is the most sensitive one compared to the other modified electrodes under investigation. The modified g-MnO2/CS/PGE was applied for selective and sensitive determination of FUR. Under the optimized experimental conditions, g-MnO2/CS/PGE provides a linear response over the concentration range of 0.05 to 4.20 mmol L-1 FUR with a low limit of detection, which was found to be 4.44 nmol L-1 (1.47 ng mL-1) for the 1st peak and 3.88 nmol L-1 (1.28 ng mL-1) for the 2nd one. The fabricated sensor exhibits a good reproducibility and selectivity and was applied successfully for the determination of FUR in its dosage forms and in spiked urine samples with good accuracy and precision.

A self-assembly of pyridine-2,6-dicarboxylate with Cu(II) and Mn(II) under ultrasonic and microwave irradiation gave the two coordination polymers [Cu(PDA)(H2O)1.5]n (1) and [Mn(PDA)(H2O)1.5]n (2). Their structures were characterized using IR, elemental analysis, X-ray diffraction (XRD) and spectroscopic methods. The corresponding α-Mn3O4 and CuO nanoparticles were synthesized by calcination of 1 and 2 in air at 600 °C.Transmission electron microscopy (TEM) reveals a sphere-like morphology for the Mn3O4 nanoparticles. Shrinkage of the particle size from 90 nm (by conventional synthesis of the precursor) to 19 nm (ultrasonicassisted)
takes place, indicating the great effect of ultrasonication. CuO nanoparticles were of semispherical (conventional and ultrasonic-assisted methods) and hexagonal shapes (microwave irradiation) with an average diameter of 7, 15 and 25 nm, respectively. The catalytic performance of the coordination polymers towards
degradation of methylene blue and methyl orange in the presence of hydrogen peroxide was studied. Using the same dose, catalyst 1 proved to be more efficient in color removal of both MB and MO than catalyst 2 did. Recycling test for 2 showed that it is a recyclable catalyst with no structural changes over three recycling
experiments.

A self-assembly of pyridine-2,6-dicarboxylate with Cu(II) and Mn(II) under ultrasonic and microwave irradiation gave the two coordination polymers [Cu(PDA)(H2O)1.5]n (1) and [Mn(PDA)(H2O)1.5]n (2). Their structures were characterized using IR, elemental analysis, X-ray diffraction (XRD) and spectroscopic methods. The corresponding α-Mn3O4 and CuO nanoparticles were synthesized by calcination of 1 and 2 in air at 600 °C.Transmission electron microscopy (TEM) reveals a sphere-like morphology for the Mn3O4 nanoparticles. Shrinkage of the particle size from 90 nm (by conventional synthesis of the precursor) to 19 nm (ultrasonicassisted)
takes place, indicating the great effect of ultrasonication. CuO nanoparticles were of semispherical (conventional and ultrasonic-assisted methods) and hexagonal shapes (microwave irradiation) with an average diameter of 7, 15 and 25 nm, respectively. The catalytic performance of the coordination polymers towards
degradation of methylene blue and methyl orange in the presence of hydrogen peroxide was studied. Using the same dose, catalyst 1 proved to be more efficient in color removal of both MB and MO than catalyst 2 did. Recycling test for 2 showed that it is a recyclable catalyst with no structural changes over three recycling
experiments.

A self-assembly of pyridine-2,6-dicarboxylate with Cu(II) and Mn(II) under ultrasonic and microwave irradiation gave the two coordination polymers [Cu(PDA)(H2O)1.5]n (1) and [Mn(PDA)(H2O)1.5]n (2). Their structures were characterized using IR, elemental analysis, X-ray diffraction (XRD) and spectroscopic methods. The corresponding α-Mn3O4 and CuO nanoparticles were synthesized by calcination of 1 and 2 in air at 600 °C.Transmission electron microscopy (TEM) reveals a sphere-like morphology for the Mn3O4 nanoparticles. Shrinkage of the particle size from 90 nm (by conventional synthesis of the precursor) to 19 nm (ultrasonicassisted)
takes place, indicating the great effect of ultrasonication. CuO nanoparticles were of semispherical (conventional and ultrasonic-assisted methods) and hexagonal shapes (microwave irradiation) with an average diameter of 7, 15 and 25 nm, respectively. The catalytic performance of the coordination polymers towards
degradation of methylene blue and methyl orange in the presence of hydrogen peroxide was studied. Using the same dose, catalyst 1 proved to be more efficient in color removal of both MB and MO than catalyst 2 did. Recycling test for 2 showed that it is a recyclable catalyst with no structural changes over three recycling
experiments.

A self-assembly of pyridine-2,6-dicarboxylate with Cu(II) and Mn(II) under ultrasonic and microwave irradiation gave the two coordination polymers [Cu(PDA)(H2O)1.5]n (1) and [Mn(PDA)(H2O)1.5]n (2). Their structures were characterized using IR, elemental analysis, X-ray diffraction (XRD) and spectroscopic methods. The corresponding α-Mn3O4 and CuO nanoparticles were synthesized by calcination of 1 and 2 in air at 600 °C.Transmission electron microscopy (TEM) reveals a sphere-like morphology for the Mn3O4 nanoparticles. Shrinkage of the particle size from 90 nm (by conventional synthesis of the precursor) to 19 nm (ultrasonicassisted)
takes place, indicating the great effect of ultrasonication. CuO nanoparticles were of semispherical (conventional and ultrasonic-assisted methods) and hexagonal shapes (microwave irradiation) with an average diameter of 7, 15 and 25 nm, respectively. The catalytic performance of the coordination polymers towards
degradation of methylene blue and methyl orange in the presence of hydrogen peroxide was studied. Using the same dose, catalyst 1 proved to be more efficient in color removal of both MB and MO than catalyst 2 did. Recycling test for 2 showed that it is a recyclable catalyst with no structural changes over three recycling
experiments.

Coordination polymers acquired much interest due to their powerful applications. Herein, coordination polymer of the formula {[Fe(PZDC)Cl(H2O)2]}n has been prepared conventionally and ultrasonically. The structure was investigated using elemental analysis, IR and X-ray diffraction (XRD). The ultrasonic-assisted synthesis steers the formation of the crystalline coordination polymer while the conventional method leads to the amorphous phase. Calcination of the synthesized coordination polymers was made in glass tubes (length ¼ 200 mm and width ¼ 15 mm) under air at variable temperatures. Depending on the calcination conditions, different iron oxide phases/polymorphs were produced. Maghemite; γ-Fe2O3 was formed by heat-treatment at 350 �C for 1 h regardless of the synthesis way of the precursor. X-ray single phase of hematite; α-Fe2O3 was obtained by calcination of the conventionally prepared precursor at 450 �C for 1 h. Nitrogen adsorption-desorption isotherms showed that, the specific surface areas of the γ-Fe2O3 (conventionally produced precursor), γ-Fe2O3 (ultrasonically formed precursor) and α-Fe2O3 are 125, 132 and 30.5 m2g-1, respectively. Magnetic measurements showed
that the best properties are exhibited by γ-Fe2O3 NPs synthesized from the conventionally prepared precursor; highest values of saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) are obtained.On the other hand α-Fe2O3 showed the lowest magnetic properties. The activity of prepared coordination polymers and iron oxide phases for removal of methylene blue (MB) was tested. γ-Fe2O3 (conventionally formed (precursor) showed the highest adsorption efficiency (~22%). On the other side, the coordination polymer (conventionally prepared) exhibited the best removal efficiency of methylene blue in a Fenton-like process. Degradation efficiency of 97.2% was achieved in a very short time (15 min).