This document describes a study on using different forms of polyaniline (PANI) - Emeraldine Base PANI (EB-PANI), Emeraldine Salt PANI (ES-PANI), and Leuco Emeraldine Base PANI (LEB-PANI) - as sensing materials for detecting dissolved oxygen levels in solutions. The PANI forms were characterized using UV-Vis spectroscopy and their oxygen sensitivity was evaluated using cyclic voltammetry. The cyclic voltammetry measurements showed variations in current corresponding to different oxygen concentrations, indicating the potential of using PANI-coated electrodes as dissolved oxygen sensors. In particular, results showed LEB-PANI may be suitable for detecting low concentrations of dissolved oxygen in
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
Photochemistry Mediated Synthesis and Characterization of Thyroxine Capped Si...priyanka raviraj
Objective:
Silver nanoparticles (AgNPs) are one of the noble metal nanoparticles studied due to their amenability of synthesis, functionalization and ease of detection. Synthesis of silver nanoparticles using thyroxine as a reducing and capping agent through the one step photochemical method
Characterization of synthesized silver nanoparticles (Thy-AgNPs)
1. UV-Spectroscopy Analysis
2. Fourier Transforms-Infra Red Spectroscopy (FT-IR)
3. High Resolution Transmission Electron Microscopy(HR-TEM)
4. Field Emission Scanning Electron Microscopy(FE-SEM)
5. Dynamic Light Scattering (DLS)
6. Zeta potential
Uses:
*AgNPs have unique optical, electrical, and thermal properties
*Exhibit high plasmon efficiency
*More sensitive towards localized surface plasmon resonance
*Less time consuming, economic and more ecofriendly
*It is used in electronics, food industry, cosmetics, photochemical, biomedicine and chemistry.
Using Tunisian Phosphate Rock and Her Converted Hydroxyapatite for Lead Remov...IJERA Editor
Natural and synthesis apatites represent a cost effective soil amendment, which can be used for in situ reduction of lead bioavailability and mobility. In our previous work, we selected Tunisian Phosphate Rock (TPR) and Hydroxyapatite (CaHAp) as promising minerals for the removal of lead from aqueous solutions. X-ray powder diffraction patterns (DRX), Infra Red (IR), Thermogravimetric analysis (TGA) and Scanning Electron Microscopy (SEM) were used to characterize TPR and CaHAp. CaHAp was prepared from TPR and employed for the removal of Pb2+ ions at different concentrations from aqueous solution to determine the adsorption properties of CaHAp and compare them with those of a TPR. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of lead ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio of 1.69. The maximum adsorption capacity of CaHAp for Pb2+ ions at 25 °C was 1.806 mmol /g relative to 1.035 mmol /g for TPR at the same temperature. The higher capacity of CaHAp was explained in terms of its porosity and crystallinity. The Pb2+ ions sorption results could be modelled by the Langmuir and Freundlich isotherms. The simulations of adsorption isotherms of Pb2+ on CaHAp allow us to conclude that there is a good correlation between the experimental data and the Langmuir model. On TPR, we show a good correlation between the experimental data and the Langmuir and Freundlich model.
Novel pH sensor based on fiber optic coated bromophenol blue and cresol redTELKOMNIKA JOURNAL
Fabrication of pH sensor based on fiber optic coated bromophenol blue and cresol red has been done. Briefly, jacket in the middle part of the fiber optic was removed for 5 cm. Then the core of each of fiber optics was washed in ethanol. Nitric acid, demineralized water, and ethanol again consecutively. Then the cleaned core was coated using active material using sol-gel immobilization technique. Tetraehyl orthosilicate was used as a binder in the immobilization of active materials. Bromophenol blue will start change the color to yellow at below pH 3.00±0.01 and blue at above pH 4.60±0.01, while the cresol red will start change the color to yellow at below pH 7.20±0.01 and violet at above pH 8.80±0.01. The pH sensors which have been made show the sigmoidal response over pH from 1.00±0.01 to 11.00±0.01. The sensor has a better performance in comparation with the other sensor.
Equilibrium and Kinetics Adsorption of Cadmium and Lead Ions from Aqueous Sol...theijes
Sourcing cheap adsorbents for the treatment of waste water is imperative for local environments. The adsorption of cadmium (Cd) and lead (Pb) from aqueous solution onto bamboo activated carbon prepared by chemical activation with ZnCl2 was investigated. The unwashed chemical activated bamboo carbon (UCABC) achieved up to 87.81% and 96.45% removal of Cd and Pb at pH-5 and 11, respectively. Removal equilibrium was attained within 1hr and 2.5hrs for Cd and Pb, respectively. The Cd and Pb adsorption increased with adsorbent dosage decrease while removal rate (%) increased with Cd and Pb concentration. Adsorption isotherm of Cd and Pb onto UCABC was determined and correlated with four isotherm models (Langmuir, Freundlich, Temkin and Hills). The equilibrium data fitted into Freundlich Cd (R2 = 0.9873, SSE = 0.045), Pb (R2 =0.9903, SSE = 0.051); Temkin Cd (R2 =0.9730, SSE = 0.052), Pb (R2 = 0.9079, SSE = 0.056); Hills Cd (R2 = 0.9961, SSE = 0.048), Pb (R2.= 0.9183, SSE = 0.053) and Langmuir Cd (R2 = 0.9653, SSE = 0.302), Pb (R2 = 0.9899, SSE = 0.136) isotherms. The Freundlich fitting showed isotherm adsorption capacity constants Kf = 7.843 and 5.098 (mg/g) for Cd and Pb, respectively. Furthermore, their adsorption kinetics correlated with the Pseudo-first order, Pseudo-second order and Intra-particle diffusion models and could be best described by the Pseudo-second order equation, suggesting chemisorptions as the limiting process. This study demonstrated that the UCABC can remove Cd2+ and Pb+ ions from aqueous solution to avert expensive commercial adsorbents
This Presentation Clarifying about potable Water analysis and their methods which i gave training on operation and maintenance team for Oman Al Ghubrah Independence Water Project (SWRO Desalination 42 MIGD)
Preparation, characterization and application of sonochemically doped fe3+ in...eSAT Journals
Abstract In this present study, mechanistic investigation of ultrasound–assisted dye decolorization/degradation was investigated using sonochemically prepared Fe3+ doped ZnO. Fe3+ doped ZnO nanoparticle was prepared under ultrasound (20 kHz) irradiation using a doping concentration of 2 wt% of Fe(III). To investigate the catalytic activity of Fe3+ doped ZnO, Acid Red 14 (azo dye) was chosen for decolorization/degradation using sonolysis, photocatalysis and sono–photocatalysis processes. To study the influence of dopant onto structure, crystallinity, and optical properties, different analytical analyses were performed such as X–ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Zeta potential, Delsa Nano Particle Size Analyzer (PSA), Vibrating Sample Magnetometer analysis (VSM) and Field Emission Scanning Electron Microscopy (FE–SEM) etc. For photocatalytic experiments, a blended high pressure mercury UV lamp with maximum peak emission at 365 nm was used. The decolorization/degradation of dye with modified photocatalyst showed faster reaction kinetics under sono–photocatalytic process. Ultrasound showed an additive effect for degradation/decolorization process. The maximum decolorization of AR14 was achieved (~ 82%) under sono–photocatlytic process with an initial dye concentration of 20 ppm. The sono–photocatalysis process showed 1.4 – 1.6 higher reaction rates with Fe–doped ZnO than pure ZnO. Index Terms: ZnO, Fe–ZnO, Fe-doped ZnO, Sonocatalytic, Photocatalytic, Advanced Oxidation Process, AOP
In the present work, Graphene oxide (GO) was prepared using improved modified Hummer’s method. Reduced
Graphene oxide (rGO) is synthesized by cow urine extract using sonication and refluxing process. Tin Oxide quantum dots were
synthesized using wet chemical method. RGO/SnO2 based pellets were prepared using hydraulic press. These pellets were
characterized for glucose. Structural and optical characterization of GO, rGO and SnO2 quantum dots was performed using XRD,
UV-visible and FTIR. The sensors show good response towards glucose.
Microwave Assist Green Synthesis of Silver Nano Particles Using Rhynchostylis...Dr. Amarjeet Singh
A novel green approach for the synthesis and
stabilization of silver nanoparticles (AgNPs) using water
extract of Rhynchostylisretusa(L.) Blume leaf has been
developed. As obtained, the nanoparticles are characterized by
UV-visible (UV-Vis), FTIR, X-ray diffraction (XRD) and SEM
analysis. The crystalline nature of the AgNPs is confirmed by
the prominent peaks in the XRD pattern. FTIR spectra suggest
that the possible biomolecules are responsible for the efficient
stabilization of the sample. The prepared nanoparticle shows
good antioxidant activity.
adsorption of methylene blue onto xanthogenated modified chitosan microbeadsSiti Nadzifah Ghazali
Methylene Blue (MB) is thiazine dyes that widely use to color product in many industry such as textile, printing, leather, cosmetic and paper. Xanthogenated-Modified Chitosan Microbeads (XMCM) is use to observe the new alternative adsorbent in removing MB from water body through adsorption process. The interactions between MB and functional group in XMCM were confirmed by Fourier Transform Infrared (FT-IR) spectra. Several parameters that influence adsorption ability such as the effect of adsorbent dosage of XMCM and the effect of initial pH of MB aqueous solution were studied. This study were done at optimum condition which is at pH 4 of initial pH of MB solution, 0.01 g of initial XMCM dosage, 6 hours stirring time and temperature of (30 ± 2 ℃). The adsorption data fit well Langmuir model more than Freundlich model. Based on Langmuir model, the maximum monolayer adsorption capacity of MB was 21.62 mg g-1 which indicated that XMCM can be a new alternative adsorbent for removing MB.
Synthesis and characterization of Silver NanoparticlesIJMERJOURNAL
ABSTRACT: Different methods may be used to produce nanoparticles, for instance in 1951 Turkevich and co-workers proposed that gold nanoparticles can be produced from the reaction of trisodum citrate, which acts as a stabilizing and reducing agent, with chloroauric acid, the source of gold nanoparticles. By changing chloroauric acid to silver nitrate, silver nanoparticles can instead be produced. Despite being widely used, there is a debate in the literature on the way the reagents and conditions, used for the Turkevich method, affect the size and shape of the silver nanoparticles produced. In view of this, silver nanoparticles have been synthesised through the Turkevich method using different reaction conditions, namely the reaction temperature and concentration of sodium citrate used. Characterisation techniques were then used to determine the size and shape of the silver nanoparticles produced. It was found that increasing the temperature increased the size of the nanoparticles through SEM, although DLS showed the opposite trend. Furthermore, at higher temperatures the formation of rod-like particles could be observed, as opposed to more spherical particles at lower temperatures.
Photochemistry Mediated Synthesis and Characterization of Thyroxine Capped Si...priyanka raviraj
Objective:
Silver nanoparticles (AgNPs) are one of the noble metal nanoparticles studied due to their amenability of synthesis, functionalization and ease of detection. Synthesis of silver nanoparticles using thyroxine as a reducing and capping agent through the one step photochemical method
Characterization of synthesized silver nanoparticles (Thy-AgNPs)
1. UV-Spectroscopy Analysis
2. Fourier Transforms-Infra Red Spectroscopy (FT-IR)
3. High Resolution Transmission Electron Microscopy(HR-TEM)
4. Field Emission Scanning Electron Microscopy(FE-SEM)
5. Dynamic Light Scattering (DLS)
6. Zeta potential
Uses:
*AgNPs have unique optical, electrical, and thermal properties
*Exhibit high plasmon efficiency
*More sensitive towards localized surface plasmon resonance
*Less time consuming, economic and more ecofriendly
*It is used in electronics, food industry, cosmetics, photochemical, biomedicine and chemistry.
Using Tunisian Phosphate Rock and Her Converted Hydroxyapatite for Lead Remov...IJERA Editor
Natural and synthesis apatites represent a cost effective soil amendment, which can be used for in situ reduction of lead bioavailability and mobility. In our previous work, we selected Tunisian Phosphate Rock (TPR) and Hydroxyapatite (CaHAp) as promising minerals for the removal of lead from aqueous solutions. X-ray powder diffraction patterns (DRX), Infra Red (IR), Thermogravimetric analysis (TGA) and Scanning Electron Microscopy (SEM) were used to characterize TPR and CaHAp. CaHAp was prepared from TPR and employed for the removal of Pb2+ ions at different concentrations from aqueous solution to determine the adsorption properties of CaHAp and compare them with those of a TPR. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of lead ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio of 1.69. The maximum adsorption capacity of CaHAp for Pb2+ ions at 25 °C was 1.806 mmol /g relative to 1.035 mmol /g for TPR at the same temperature. The higher capacity of CaHAp was explained in terms of its porosity and crystallinity. The Pb2+ ions sorption results could be modelled by the Langmuir and Freundlich isotherms. The simulations of adsorption isotherms of Pb2+ on CaHAp allow us to conclude that there is a good correlation between the experimental data and the Langmuir model. On TPR, we show a good correlation between the experimental data and the Langmuir and Freundlich model.
Novel pH sensor based on fiber optic coated bromophenol blue and cresol redTELKOMNIKA JOURNAL
Fabrication of pH sensor based on fiber optic coated bromophenol blue and cresol red has been done. Briefly, jacket in the middle part of the fiber optic was removed for 5 cm. Then the core of each of fiber optics was washed in ethanol. Nitric acid, demineralized water, and ethanol again consecutively. Then the cleaned core was coated using active material using sol-gel immobilization technique. Tetraehyl orthosilicate was used as a binder in the immobilization of active materials. Bromophenol blue will start change the color to yellow at below pH 3.00±0.01 and blue at above pH 4.60±0.01, while the cresol red will start change the color to yellow at below pH 7.20±0.01 and violet at above pH 8.80±0.01. The pH sensors which have been made show the sigmoidal response over pH from 1.00±0.01 to 11.00±0.01. The sensor has a better performance in comparation with the other sensor.
Equilibrium and Kinetics Adsorption of Cadmium and Lead Ions from Aqueous Sol...theijes
Sourcing cheap adsorbents for the treatment of waste water is imperative for local environments. The adsorption of cadmium (Cd) and lead (Pb) from aqueous solution onto bamboo activated carbon prepared by chemical activation with ZnCl2 was investigated. The unwashed chemical activated bamboo carbon (UCABC) achieved up to 87.81% and 96.45% removal of Cd and Pb at pH-5 and 11, respectively. Removal equilibrium was attained within 1hr and 2.5hrs for Cd and Pb, respectively. The Cd and Pb adsorption increased with adsorbent dosage decrease while removal rate (%) increased with Cd and Pb concentration. Adsorption isotherm of Cd and Pb onto UCABC was determined and correlated with four isotherm models (Langmuir, Freundlich, Temkin and Hills). The equilibrium data fitted into Freundlich Cd (R2 = 0.9873, SSE = 0.045), Pb (R2 =0.9903, SSE = 0.051); Temkin Cd (R2 =0.9730, SSE = 0.052), Pb (R2 = 0.9079, SSE = 0.056); Hills Cd (R2 = 0.9961, SSE = 0.048), Pb (R2.= 0.9183, SSE = 0.053) and Langmuir Cd (R2 = 0.9653, SSE = 0.302), Pb (R2 = 0.9899, SSE = 0.136) isotherms. The Freundlich fitting showed isotherm adsorption capacity constants Kf = 7.843 and 5.098 (mg/g) for Cd and Pb, respectively. Furthermore, their adsorption kinetics correlated with the Pseudo-first order, Pseudo-second order and Intra-particle diffusion models and could be best described by the Pseudo-second order equation, suggesting chemisorptions as the limiting process. This study demonstrated that the UCABC can remove Cd2+ and Pb+ ions from aqueous solution to avert expensive commercial adsorbents
This Presentation Clarifying about potable Water analysis and their methods which i gave training on operation and maintenance team for Oman Al Ghubrah Independence Water Project (SWRO Desalination 42 MIGD)
Preparation, characterization and application of sonochemically doped fe3+ in...eSAT Journals
Abstract In this present study, mechanistic investigation of ultrasound–assisted dye decolorization/degradation was investigated using sonochemically prepared Fe3+ doped ZnO. Fe3+ doped ZnO nanoparticle was prepared under ultrasound (20 kHz) irradiation using a doping concentration of 2 wt% of Fe(III). To investigate the catalytic activity of Fe3+ doped ZnO, Acid Red 14 (azo dye) was chosen for decolorization/degradation using sonolysis, photocatalysis and sono–photocatalysis processes. To study the influence of dopant onto structure, crystallinity, and optical properties, different analytical analyses were performed such as X–ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Zeta potential, Delsa Nano Particle Size Analyzer (PSA), Vibrating Sample Magnetometer analysis (VSM) and Field Emission Scanning Electron Microscopy (FE–SEM) etc. For photocatalytic experiments, a blended high pressure mercury UV lamp with maximum peak emission at 365 nm was used. The decolorization/degradation of dye with modified photocatalyst showed faster reaction kinetics under sono–photocatalytic process. Ultrasound showed an additive effect for degradation/decolorization process. The maximum decolorization of AR14 was achieved (~ 82%) under sono–photocatlytic process with an initial dye concentration of 20 ppm. The sono–photocatalysis process showed 1.4 – 1.6 higher reaction rates with Fe–doped ZnO than pure ZnO. Index Terms: ZnO, Fe–ZnO, Fe-doped ZnO, Sonocatalytic, Photocatalytic, Advanced Oxidation Process, AOP
In the present work, Graphene oxide (GO) was prepared using improved modified Hummer’s method. Reduced
Graphene oxide (rGO) is synthesized by cow urine extract using sonication and refluxing process. Tin Oxide quantum dots were
synthesized using wet chemical method. RGO/SnO2 based pellets were prepared using hydraulic press. These pellets were
characterized for glucose. Structural and optical characterization of GO, rGO and SnO2 quantum dots was performed using XRD,
UV-visible and FTIR. The sensors show good response towards glucose.
Microwave Assist Green Synthesis of Silver Nano Particles Using Rhynchostylis...Dr. Amarjeet Singh
A novel green approach for the synthesis and
stabilization of silver nanoparticles (AgNPs) using water
extract of Rhynchostylisretusa(L.) Blume leaf has been
developed. As obtained, the nanoparticles are characterized by
UV-visible (UV-Vis), FTIR, X-ray diffraction (XRD) and SEM
analysis. The crystalline nature of the AgNPs is confirmed by
the prominent peaks in the XRD pattern. FTIR spectra suggest
that the possible biomolecules are responsible for the efficient
stabilization of the sample. The prepared nanoparticle shows
good antioxidant activity.
adsorption of methylene blue onto xanthogenated modified chitosan microbeadsSiti Nadzifah Ghazali
Methylene Blue (MB) is thiazine dyes that widely use to color product in many industry such as textile, printing, leather, cosmetic and paper. Xanthogenated-Modified Chitosan Microbeads (XMCM) is use to observe the new alternative adsorbent in removing MB from water body through adsorption process. The interactions between MB and functional group in XMCM were confirmed by Fourier Transform Infrared (FT-IR) spectra. Several parameters that influence adsorption ability such as the effect of adsorbent dosage of XMCM and the effect of initial pH of MB aqueous solution were studied. This study were done at optimum condition which is at pH 4 of initial pH of MB solution, 0.01 g of initial XMCM dosage, 6 hours stirring time and temperature of (30 ± 2 ℃). The adsorption data fit well Langmuir model more than Freundlich model. Based on Langmuir model, the maximum monolayer adsorption capacity of MB was 21.62 mg g-1 which indicated that XMCM can be a new alternative adsorbent for removing MB.
Synthesis and characterization of Silver NanoparticlesIJMERJOURNAL
ABSTRACT: Different methods may be used to produce nanoparticles, for instance in 1951 Turkevich and co-workers proposed that gold nanoparticles can be produced from the reaction of trisodum citrate, which acts as a stabilizing and reducing agent, with chloroauric acid, the source of gold nanoparticles. By changing chloroauric acid to silver nitrate, silver nanoparticles can instead be produced. Despite being widely used, there is a debate in the literature on the way the reagents and conditions, used for the Turkevich method, affect the size and shape of the silver nanoparticles produced. In view of this, silver nanoparticles have been synthesised through the Turkevich method using different reaction conditions, namely the reaction temperature and concentration of sodium citrate used. Characterisation techniques were then used to determine the size and shape of the silver nanoparticles produced. It was found that increasing the temperature increased the size of the nanoparticles through SEM, although DLS showed the opposite trend. Furthermore, at higher temperatures the formation of rod-like particles could be observed, as opposed to more spherical particles at lower temperatures.
Hollow-Polyaniline-Sphere-Coated Sensor For Measuring Gas-Phase OH Radicals A...IJERA Editor
In advanced oxidation processes, OH radicals play a crucial role in enhancing the removal efficiency of volatile
organic compounds. In this paper, hollow polyaniline (PANI) spheres were coated onto a conducting ceramic
honeycomb substrate to form a PANI sensor for detecting the concentration of OH radicals in the amorphous
phase. The hollow PANI spheres were effectively synthesized through a double-surfactant-layer-assisted
polymerization process by using Fe3O4 nanoparticle as the core template. The PANI shell thickness, morphology
characterizations and specific surface area were controlled by altering the weight of aniline monomers. The
electrical conductivity served as a function of the operating temperature and specific surface area, which is a
characteristic behavior of conductive polymer materials in the atmosphere. At an optimized temperature of
125°C and specific surface area of 1435 m2
/g, the PANI sensor reacted with a high amount of OH radicals
generated from the decomposition of ozone over α–FeOOH nanoparticles. The conductometric response after the
OH radical attack increased exponentially with the concentration of the OH radicals.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation MethodIJRES Journal
This study evaluated the effect of Fenton advanced oxidation process on the treatment of an industrial wastewater (distillery). The comparison of the effects of Fe2+ loadings, H2O2 dosages (2%(v/v)and 4%(v/v)), reaction temperature and reaction time, established optimum efficiency in terms of BOD and COD reductions. The best operating conditions for the treatment of the distillery wastewater containing 43.85 mg/L BOD concentration and 274.28 mg/L COD concentration in the raw effluent was 2% H2O2 dosage at constant loadings of Fe2+ (1.5 g), 80 oC pretreatment temperature, and 1 h reaction time. At this optimized condition, the BOD content reduced to about 35 mg/L (about 21% removal) and COD content reduced to about 53 mg/L (about 81% removal). There was a complete removal of the initial colour present in the wastewater after the treatment process. The process proved the ability to effectively reduce the COD content which when high in industrial wastewaters can lead to serious impacts to the environment.
Synthesis of 2-aminocyclopent-1-ene-1-carbodithioic acid (ACA) Capped Silver ...IJERA Editor
The present work deals with the formation, morphology and photophysical activity of the 2-aminocyclopent-1-ene-1-carbodithioic acid (ACA) Capped Silver nanoparticles via chemical reduction method. The method utilizes a simple chemical reaction of silver idodide and sodium borohydride. The advantages of this method are ease of preparation, convenience in use and especially, that the obtained silver nano particles are uniform in their shapes and sizes. This is important for fluorescence & bio-evolution measurements. Furthermore, UV-visible (UV-vis) spectroscopy is employed to monitor the formation process of the nano particles and to determine the optimum conditions for the preparation of stable and highly fluorescence-active silver colloids. Specifically, we observed changes in the shapes of the silver nano particles during the formation. This may be helpful in understanding the growth of the nano particles and creates a new dimension in controlling the shapes of the nano particles.SEM, TEM and XRD studies are carried out. The suitability of ACA capped Ag-NPs as Biomarkers is also Tested by Fluorescence study.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Synthesis & Characterization of Fluorescent Silver Nanoparticles stabilized b...IJERA Editor
Synthesis of silver nanoparticles (Ag-NPs) was achieved by a simple green procedure using Tinospora Cordifolia leaf extract as stabilizer/reducing agents. Ag-NPs in the size range of 2–19 nm is obtained by the treatment of aqueous silver ions with leaf extracts of Tinospora Cordifolia. This eco-friendly approach is simple, amenable for large scale commercial production and technical applications. Further, photoluminiscence studies of these Ag-NPs were recorded & suggested that the present particles were suitable for fluorescence emitting probes. These red emitting Ag-NPs exhibited distinct fluorescence properties (both emission and stokeshift).
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Synthesis, Characterization and Electrical Properties of Polyaniline Doped wi...IJERA Editor
The polyaniline were prepared by using different inorganic and organic acids via oxidative polymerization
method. The prepared samples were characterized by FTIR, the peaks are found to be at 507 cm˗1, 592 cm˗1, 798
cm˗1, 1138 cm˗1, 1244 cm˗1, 1302 cm˗1, 1471 cm˗1 and 1556 cm˗1. These predominant peaks may be
confirming the formation of polyaniline. The structural analysis was studied by employing XRD; found that
polyaniline is amorphous in nature. The SEM studies reveal that they are agglomerated, irregular and size of
these grain increases with increasing amount of polyaniline with different organic and inorganic acids. The dc
conductivity (dc) as a function of temperature (T) for polyaniline is studied in the temperature range from 30 to
1600C. At higher temperature it is found that conductivity increases because of hopping of polarons from one
localized states to another localized states. The ac conductivity of polyaniline was prepared by oxalic acid show
high conductivity at 106 Hz. This is due to the space charge polarization and electrode polarizations.
Electrochemical Behavior of L-Tyrosine at Poly (Dicyclomine Hydrochloride) Fi...paperpublications3
Abstract: An electrochemical method for the determination of L-Tyrosine (LTY) using a dicyclomine hydrochloride (DICY) polymer film modified carbon paste electrode. The surface morphology of poly (DICY) modified carbon paste electrode was characterized by SEM. The modified electrode showed excellent electro catalytic activity towards the oxidation of LTY in 0.1 M phosphate buffer solution of pH 6.5. The effect of pH, concentration and scan rate were studied at the bare carbon paste electrode and poly (DICY) modified carbon paste electrode were investigated. Increase of LTY concentration shows linear increase in oxidation peak current. The linear relationship was obtained between the anodic peak current (Ipa) and concentration LTY in range 2×10-5 M to 1×10-3 M with correlation coefficient of 0.9984. The low detection limit (LOD) and low quantification limit (LOQ) of LTY were detected. The cyclic voltammetric studies indicated that the oxidation of LTY at the modified electrode surface was irreversible; adsorption controlled and undergoes a one electron transfer process at the poly (DICY) film modified carbon paste electrode. The modified electrode showed high sensitivity, detection limit, high reproducibility, easy preparation and regeneration of the electrode surface.
Novel Conductive Nano-composite Ink Based on Poly Aniline, Silver Nanoparticl...Khaled Abdel-Razeq
Novel Conductive Nano-composite Ink Based on Poly Aniline, Silver Nanoparticles and Nitrocellulose
Egypt. J. Chem. 59, No. 4, pp. 429 - 443 (2016)
http://ejchem.js.iknito.com/article_1101.html
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
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C05521422
1. IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org
ISSN (e): 2250-3021, ISSN (p): 2278-8719
Vol. 05, Issue 05 (May. 2015), ||V2|| PP 14-22
International organization of Scientific Research 14 | P a g e
Polyaniline-coated electrodes for detection of dissolved oxygen
levels in solution
Thien Dien TO1
, Tung Son Vinh NGUYEN1
, Tien Van TRAN1
, An Duy
NGUYEN1
, Ngan Nguyen LE1
, Tin Chanh Duc DOAN1,
*, Chien Mau DANG1
1
Laboratory for Nanotechnology (LNT), Vietnam National University - Ho Chi Minh City, Community 6, Linh
Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam;
Abstract: Emeraldine Base Polyaniline (EB-PANI), Emeraldine Salt Polyaniline (ES-PANI) and Leuco
Emeraldine Base Polyaniline (LEB-PANI) were studied for detection of different dissolved oxygen levels in
solutions. Optical properties of the polyaniline forms were characterized by Ultraviolet-Visible (UV-Vis)
spectroscopy. To identify oxygen sensitivity of the PANI films, cyclic voltametry (CV) measurements were
performed with the PANI films drop-casted on working platinum electrodes. Electrolyte solution in the CV
measurements was based on phosphate buffer with salinity of 20‰ and pH 7.3. Pure nitrogen and oxygen gases
were used to change oxygen levels that were monitored by a commercial dissolved oxygen probe. CV
measurements showed the variations of current in corresponding to different oxygen concentrations. The
correlation of the current and dissolved oxygen levels was also determined. The results exhibited the possibility
of using LEB-PANI as sensing electrodes for detection of low concentrations of dissolved oxygen in
aquaculture farming.
Keywords: cyclic voltametry, dissolved oxygen detection, leucoemeraldine base polyaniline, oxidation doping,
polyaniline
I. INTRODUCTION
Dissolved oxygen (DO) concentration in water is one of the most important parameters of water for
aquaculture farming, hence it is needed to be continuously monitored and controlled. DO measurement is used
to identify amount of oxygen dissolved in a solution. Adequate DO concentration in water indicates good
quality of water for aquaculture farming. When DO concentration is lower than 5 mg/l, aquacultural life is in
danger. Large amount of fish might be fatal if DO concentration reaches 1-2 mg/l for several hours.
Commercial DO probes have been in market with various types from different manufacturers. Most DO
sensors employ sensing technologies including optical based method which is commonly referred to as
luminescent and the Clark electrochemical or membrane-covered electrode [1]. Hemera, Sacomam, Thethys
Instruments, YSI supply DO sensors working based on optical method. Amount of oxygen is proportional to
luminescence intensity of chemical dyes. Horiba, Greenspan Analytical, In-situ, Eutech-Thermo Scientific use
polarographic electrodes and electrochemical advanced technologies. However, high cost of these sensors has
hampered the application of these sensor systems in small and medium shrimp/fish farms. Therefore, the need of
compact DO sensor development with low cost, simple operation has been increasing and has attracted the
interest of many scientists in this field.
The optical method was used to measure DO levels in micro-scale water flows with an oxygen
quenchable luminophore platinum (II) octaethyporphrin bound with thin polystyrene film [2]. Another work also
used the optical method to measure DO concentrations within cell culture media by analyzing fluorescence
intensity of dextran and ruthenium complex immobilized on poly(ethylene glycol) diacrylate microarray [3].
However, the optical method with a complicated setup and result analysis is only suitable for measurement in
laboratories and it is difficult to apply for practical applications in aquaculture farming. Besides, electrochemical
technology has been widely used for DO sensor development [4-6]. Chou et al. [5] investigated gold/Nafion
electrodes with H2SO4 acid as a supporting electrolyte for DO detection in water. The sensitivity of DO sensors
was 38.4 µA/ppm and the lowest limit of DO was 3.8 ppm. Peng Wang and his co-workers [6] used a silicon
microprobe including Nafion coating on three platinum electrodes to measure DO levels at 0% atm, 10.5% atm
and 21% atm. The difference between two curves in linear sweep voltammetry in air-equilibrated DI water and
oxygen depleted DI water was attributed to oxygen reduction. However, the aim of this research is to measure
DO concentration in blood for biological and biomedical use; hence, DO concentrations were not high.
Moreover, repeatability was not satisfactory and the calibration curves were not established.
Recently conductive polymers have been investigated for different types of sensors [7-15] but only few
of them have been used for DO measurements. Tieman et al. [16] used ionically conductive polymer
poly(dimethyldiallylammonium chloride) coated on graphite electrodes as working electrodes to measure DO.
2. Polyaniline-coated electrodes for detection of dissolved oxygen levels in solution
International organization of Scientific Research 15 | P a g e
The authors used Pt auxilary electrode and Ag/AgCl reference electrode. DO concentration was measured by
reduction at potential of -0.40 V versus Ag/AgCl. The linearity of concentration was in the range of 1.4-9.3
ppm. In addition, polyaniline (PANI) was once investigated for DO measurement [17]. A platinum electrode
coated with PANI was examined as a potentiometric sensor. This PANI-coated electrode gave approximately 97
mV/decade of the oxygen concentration and a voltage signal of about 400 mV. A detection limit of DO was
estimated of about 5 x 10-7
mol/l. The proposed mechanism based on the oxidation of reduced form
(leucoemeraldine base PANI) leading to conversion into conducting salt PANI in the presence of oxygen
bubbling in H2SO4 solution. In this research, pH of the medium was kept lower than 7 by a mixture of H2SO4
and NaOH. The oxidative doping due to existing H2SO4 1 M solution could have caused conversion into
conducting salt PANI. Therefore, the proposed mechanism of oxidation by oxygen bubbling is still not clear.
In this report three forms of PANI including Emeraldine Base Polyaniline (EB-PANI), Emeraldine Salt
Polyaniline (ES-PANI) and Leuco Emeraldine Base Polyaniline (LEB-PANI) (Fig. 1) were investigated as
sensing materials for detection of DO levels in solution. UV-Vis spectroscopy and cyclic voltametry (CV) were
used to evaluate the DO sensitivity of these polymers. The increases in current of the CV measurements in
corresponding to different DO concentrations were observed. The results showed possibility of using PANI-
coated electrodes for DO sensors.
Figure 1. (a) Structure of EB-PANI. (b) ES-PANI. (c) LEB-PANI.
II. EXPERIMENTAL
2.1. Materials
Emeraldine Base Polyaniline (EB-PANI) (99.7%, Mw 20,000), dimethyl sulfoxide (DMSO) (99.9%),
phenylhydrazine (PHZ) (97%) were bought from Sigma Aldrich and hydrochloric acid (HCl) (37%) was bought
from Merck. Disodium hydrogen phosphates dodecahydrate (Na2HPO4.12H2O), sodium dihydrogen phosphate
dihydrate (NaH2PO4.2H2O) and sodium chloride (NaCl) were used to prepare testing solutions. All the
chemicals were used as purchased without further purification. Oxygen (O2) gas (99.999%) was supplied by
Singapore Oxygen Air Liquide Pte. Ltd.
2.2. Preparation of polymer solutions
2.2.1. EB-PANI solution
Mix 30 mg of EB-PANI with 2.7 ml DMSO, stirring for 24 hours with a magnetic stirrer at room
temperature to obtain EB-PANI solution. The solution was then filtered through a filter paper. The obtained
polymer solution had dark blue color.
2.2.2. ES-PANI solution
EB-PANI powder was protonated by HCl 0.1 M solution to obtain ES-PANI (green color). The salt was
filtered and rinsed by DI water to remove residual acid. Then ES-PANI was dried under vacuum at 60C in a
vacuum oven. 30 mg ES-PANI was dispersed in 2.7 ml DMSO to obtain ES-PANI solution. This solution
underwent ultrasonification and centrifugal mixing.
2.2.3. LEB-PANI solution
ES-PANI was mixed with PHZ 97% to obtain LEB-PANI. Then the powder was rinsed in DI water,
acetone and methanol to remove residual PHZ and dried at 60C in the vacuum oven. After that LEB-PANI was
dissolved in DMSO and this solution underwent ultrasonification and centrifugal mixing.
2.3. Fabrication of electrochemical chips
Electrochemical chips included one working electrode and one counter electrode (dimension of 3 mm x
9 mm) put separately with a distance of 3 mm. Both electrodes were made of platinum (Pt). Pt layers were
sputtered with Univex 350 (Leybold, Germany) and patterned on silicon (Si) wafers coated with 700 nm thick
SiO2 by photolithography and lift-off techniques. The Pt electrodes had a thickness of 190 nm with a titanium
adhesion layer.
4 µl of the PANI solutions was drop-casted on the working electrode of the electrochemical chips and
these chips were heated in vacuum oven at 60°C for 24 hours to remove completely DMSO.
3. Polyaniline-coated electrodes for detection of dissolved oxygen levels in solution
International organization of Scientific Research 16 | P a g e
2.4. Characterization
UV-Vis absorption spectroscopy of the PANI samples was obtained from a double beam
spectrophotometer Cary 100 (Varian, USA) in the wavelength range from 200 to 800 nm. To check oxygen
sensitivity of the PANI forms, the quartz cuvettes containing the PANI solutions were bubbled with 0.5 psi of
oxygen gas in 1-5 minutes. After each time of oxygen bubbling, UV-Vis spectra were recorded and compared.
The variation of the UV-Vis spectra in the presence of oxygen (if any) can be applied for optical DO sensors
using PANI layers as a color indicator.
The thickness of the Pt electrodes and the polymer films after fabrication was measured by a stylus
profiler Dektak 6M (Veeco, USA).
2.5. Cyclic voltametry (CV) measurements
Testing electrolyte solutions were prepared from phosphate buffer which was made from 6 g
Na2HPO4.12H2O, 0.5 g NaH2PO4.2H2O and DI water to obtain 200 ml testing solution with pH 7.3. Then 4 g
NaCl was added to make the solution have salinity of 20‰. The testing solution was prepared to imitate the
conditions of water in shrimp ponds.
The testing solutions were bubbled with nitrogen (N2) gas for 15 minutes to minimize DO
concentration in the solution, approximately 1.5 ppm. Then oxygen (O2) gas was bubbled through the solution
with a pressure of 1 psi for 15-90 seconds to create various DO concentrations in the solutions. DO
concentrations were measured by a commercial DO probe DO6400TC/T (Sensorex, US) with a measurement
range of 0-20 mg/l, 0.01 mg/l resolution and ±1.5% accuracy.
The polymer coated chips were dipped in the testing solutions in which the polymer part was immersed
completely. CV measurements were performed with a potentiostat/galvanostat PGSTAT 302N (Metrohm,
Autolab, the Netherlands) and a silver/silver chloride (Ag/AgCl) reference electrode RE-6 (Basi Inc., US). The
polymer chips were mounted on two crocodile clips (Fig. 2). The current was set from 10 µA to 10 mA, the
scanning rate was 50 mV/sec, the temperature was about 28 C ± 1 C.
Figure 2. The polymer chip mounted on two crocodile clips.
III. RESULTS AND DISCUSSION
3.1. UV-Vis spectroscopy of EB-PANI, ES-PANI and LEB-PANI
UV-Vis spectroscopy of EB-PANI, ES-PANI and LEB-PANI was carried out with Cary 100 (Varian,
USA) in the wavelength range from 200 to 800 nm. UV-Vis absorption spectra of EB-PANI, ES-PANI and
LEB-PANI in DMSO are shown in Fig. 3.
Figure 3. UV-Vis absorption spectra of EB-PANI (solid line), ES-PANI (dash line) and LEB-PANI (dash dot
line) in DMSO.
4. Polyaniline-coated electrodes for detection of dissolved oxygen levels in solution
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UV-Vis spectrum of EB-PANI in DMSO solvent shows two peaks at wavelength of 324 nm and 625
nm. This result is in good agreement with literature values [18-20]. The absorption peak at 324 nm is assigned to
the π - π* transition of the benzenoid rings. The peak at 625 nm originates from the exciton transition of the
quinoid rings [19]. The absorption spectrum of HCl-doped PANI in DMSO solvent showes peaks at 289 nm,
456 nm and 663 nm. The two bands have been assigned to the optical absorption of the polaron band [18, 20].
The absorption spectrum of LEB-PANI has only one peak at 292 nm, which is in good agreement with the
published value [21].
The UV-Vis spectra of PANI solutions with and without pure oxygen bubbling were recorded. The
quartz cuvettes containing the polymer solutions were bubbled with pure oxygen for 1-5 minutes. After each
duration of oxygen bubbling, UV-Vis spectra were recorded and compared (see Supplementary Materials for the
UV-Vis spectra of the PANI forms with oxygen bubbling). The UV-Vis spectra of EB-PANI, ES-PANI and LEB-
PANI solutions almost did not change as the oxygen gas was bubbled into the solutions. However, the UV-Vis
spectra of LEB-PANI solutions which included residual PHZ showed an increasing peak at 450 nm with an
increase in DO concentration (Figure S4 of Supplementary Materials). The color of LEB-PANI changed from
transparent to green when oxygen was bubbled into the solution. It was found that the color change was due to
oxidation of the residual PHZ in the LEB-PANI preparation (Figure S5 of Supplementary Materials).
3.2. Platinum electrodes
Series of the electrochemical chips with Pt electrodes were fabricated by photolithography, sputtering
and lift-off processes. Fig. 4 shows the fabricated Pt electrodes and a diced chip coated with the PANI film on
the working electrode. The thickness of the PANI films varied from 500 nm to several micrometers.
Figure 4. The platinum electrodes on a silicon wafer before dicing into seperate chips (left) and the diced chip
coated with the PANI film on the working electrode (right).
3.3. CV measurements of the PANI-coated chips
CV measurements were performed with the PANI-coated platinum electrode as the working electrode,
another Pt counter electrode and the Ag/AgCl reference electrode. For each CV measurement, at least two chips
of the same batch were measured to check reproducibility. The potential was scanned with various ranges and it
was found that the stable potential range of the fabricated electrodes was from -0.6 V to +1.1 V. Various DO
concentrations in the testing solutions were created by bubbling N2 for 15 minutes and O2 for 15-90 seconds. In
this study, high DO concentrations were used to check the DO sensitivity of the PANI forms. Basing on the
measurement of the commercial DO probe, 1 minute of oxygen bubbling could create 16.05 mg/l of DO
concentration in the testing solutions. Due to the limited measurement range of the commercial DO probe (i.e.
20 mg/l), the DO concentrations created by durations of oxygen bubbling larger than 1 minute were estimated
correspondingly.
3.3.1. EB-PANI coated chips
Fig. 5 shows cyclic voltammograms of the EB-PANI coated chips immersed in the testing solutions
which were bubbled with N2 and O2 for 15, 30, 60 and 90 seconds (DO concentrations ranged from 1.50 ppm to
26.00 ppm).
5. Polyaniline-coated electrodes for detection of dissolved oxygen levels in solution
International organization of Scientific Research 18 | P a g e
Figure 5. CV plots of the EB-PANI chips with N2 purging (bold solid line), O2 bubbling for 15 seconds (dot
line), 30 seconds (dash line), 60 seconds (solid line), 90 seconds (dash dot dot line).
When DO concentration in the solution increases, the magnitude of current increases with DO
concentrations from 0.015 mA to 0.085 mA at the cathode peak of -0.3 V. There is large difference in current
when DO concentration increases from 1.5 ppm (corresponding to N2 purging) to 26 ppm (90 seconds of O2
bubbling). The increase in current exhibits the DO sensitivity of the EB-PANI films. The change in current
corresponding to estimated DO concentration is 2.86 µA per 1 ppm of DO concentration. This sensitivity is
however lower than the published sensitivity of 38.4 µA/ppm [5] and 12.5 µA.cm-2
/ppm [16]. This difference in
sensitivity is due to different electrode materials and different sizes of electrodes.
The relationship between the cathode current at -0.3 V and DO concentrations was shown in Fig. 6.
The increase in current of the EB-PANI thin films follows an exponential Decay function. It was observed that
the current increased steeply from 1.5 ppm to 10 ppm DO. Beyond 16 ppm DO, the current did not change much
and it became stable. It could be attributed to the saturation of DO in the testing solution with 90 seconds of
oxygen bubbling. Therefore after this measurement, the duration of oxygen bubbling was limited not more than
90 seconds.
Figure 6. The relationship between the cathode current and DO concentrations at -0.3 V of the EB-PANI coated
chip.
3.3.2. ES-PANI coated chips
Cyclic voltammograms of the ES-PANI coated chips which were bubbled with N2 and O2 for 15, 30, 60
and 90 seconds (DO concentrations ranged from 1.50 ppm to 26.00 ppm) are shown in Fig. 7.
6. Polyaniline-coated electrodes for detection of dissolved oxygen levels in solution
International organization of Scientific Research 19 | P a g e
Figure 7. CV plots of the ES-PANI chips with N2 purging (bold solid line), O2 bubbling for 15 seconds (dot
line), 30 seconds (dash line), 60 seconds (solid line), 90 seconds (dash dot dot line).
When DO concentration in the solution increases from 1.5 ppm to 9.77 ppm, the magnitude of current
increases with DO concentrations from 0.026 mA to 0.125 mA at the cathode peak of -0.05 V. In comparison
with the EB-PANI chips, the cathode peak is found to shift to -0.05 V. The change in current of the ES-PANI
chips is much larger (11.97 µA/ppm of DO concentration) in the range of 1.5-9.77 ppm DO. However, the
current decreases when DO concentration increases to 16.05 ppm (corresponding to 60 seconds of oxygen
bubbling). Two ES-PANI chips of the same measurement gave the same results. The instable increase of the
current can be attributed to the scratched ES-PANI film after the CV measurements (Figure S6 of
Supplementary Materials). It should be noted that the ES-PANI layer was not durable. The layer was stripped
off gradually after the CV scans from 1.5 ppm to 26 ppm DO and was removed completely after two times of
CV scans. The stripping of the ES-PANI layer can be due to dispersion of the conductive ES-PANI particles
which were charged under an electrical field in the electrolyte solution.
3.3.3. LEB-PANI coated chips
Fig. 8 shows the cyclic voltammograms of the LEB-PANI coated chips exposed to oxygen bubbling for
15, 30, 60 and 90 seconds. Similar to the ES-PANI chips, the cathode peak of the LEB-PANI is -0.05 V. This
peak is similar to the reduction peak of -0.03 V of LEB-PANI in CV measurements at pH 1 of Edward Song et
al. [22].
This potential indicated the reduction of LEB-PANI film at the cathode. Large increase in magnitude of
the current is also observed when DO concentrations increased from 1.5 ppm (corresponding to N2 purging) to
26 ppm (1.5 minutes of oxygen bubbling). The current increases with DO concentrations from 0.018 mA to 0.1
mA at -0.05 V. Fig. 9 shows the relationship between the cathode current at -0.05 V and DO concentrations. The
increase in current of the LEB-PANI thin films also follows an exponential Decay function similar to the EB-
PANI films. The current of the LEB-PANI films increases steeply from 1.5 ppm to 10 ppm DO and does not
change much after 15 ppm DO. The change in current corresponding to estimated DO concentration is 3.35 µA
per 1 ppm of DO concentration. The results showed that the DO sensitivity of the LEB-PANI coated chips is
higher than the EB-PANI form.
Figure 8. CV plots of the LEB-PANI chips with N2 purging (bold solid line), O2 bubbling for 15 seconds (dot
line), 30 seconds (dash line), 60 seconds (solid line), 90 seconds (dash dot dot line).
7. Polyaniline-coated electrodes for detection of dissolved oxygen levels in solution
International organization of Scientific Research 20 | P a g e
Figure 9. The relationship between the cathode current and DO concentrations at -0.05 V of the LEB-PANI
coated chip.
3.3.4. Stability of the PANI electrodes
To check reversibility and consistency of the current increase between nitrogen and oxygen bubbling,
the CV measurements of the PANI chips were performed when the chipswere exposed to bubbling nitrogen (15
minutes) and oxygen (30 seconds) for two times. CV plots after two times of oxygen bubbling (9.77 ppm DO)
are almost the same (Figure S7 of Supplementary Materials). Therefore, the PANI electrode chips have good
reversibility.
To check stability of the PANI electrodes, the CV measurements of the PANI electrodes were
performed as long as the CV plots could be obtained. DO concentration varied from 1.50 ppm to 26.00 ppm for
the CV measurements of each chip. The EB-PANI electrodes could be measured for 5 weeks and the LEB-PANI
layers could be measured for 7 weeks whereas the ES-PANI electrodes could only be measured for 1-2 weeks.
The increase of the cathode current and DO concentrations of the EB-PANI and LEB-PANI electrodes in 5 and
7 weeks plotted from the CV scans also follows an exponential Decay function (Figure S8 and Figure S9 of
Supplementary Materials). The variations in the current of the EB-PANI and LEB-PANI chips were observed.
The current signal of the EB-PANI chips was stable for 2 weeks and decreased in the following weeks. For the
LEB-PANI chips, although there was large fluctuation at high DO concentrations, the current was somehow
stable at below 10 ppm DO after 7 weeks.
3.3.5. Possible sensing mechanism
The cathode reaction relating to the redox reaction of oxygen in solution with the PANI films coated on
the Pt electrode is shown in the following reactions (1) and (2). For simplicity, a general sign is used in the
reaction (1), in which PANI represents different forms of PANI and [PANI]n-
represents the different
electrochemical redox states of PANI which have been reported in many studies [23-25].
PANI + n e → [PANI]n-
(1)
O2 + 4 e → 2 O2-
(2)
Depending on the form of PANI (EB-PANI, ES-PANI or LEB-PANI) the difference in the consumed
number of electrons causes the different cathodic potentials (as observed in the CV measurements). The
cathodic potential of EB-PANI is more polarized than that of LEB-PANI. This leads to the fact that the oxygen
reduction with the LEB-PANI electrode is easier than with the EB-PANI and the higher DO sensitivity of the
LEB-PANI coated chips.
In the reaction (1), the PANI film receives electrons to transform into a charge state [PANI]n-
and a part
of charge is transferred to oxygen to cause the reaction (2). The CV plots of the PANI forms show only one
cathode peak. It could be implied that the reduction reaction is followed by one-step reaction. The reduced
oxygen O2-
may be combined with [PANI]n-
to produce a new compound like [PANI-O2] (Fig. 10). The same
structure of [PANI-O2] was also proposed by D. V. Zhuzhel’skii [26].
8. Polyaniline-coated electrodes for detection of dissolved oxygen levels in solution
International organization of Scientific Research 21 | P a g e
Figure 10. Mechanism of reduced oxygen at the PANI-coated Pt electrode.
Figure 11. Resonance in [PANI-O2] structure to form oxoniumcations.
In the presence of DO in solution, two oxygen atoms approach the PANI films and attach to the
benzene rings of the PANI. The resonance in the structure then occurs and oxonium ions are generated (Fig. 11).
When there are more oxygen molecules, more oxonium ions are formed and the conductivity of the PANI films
increases. The increase in oxygen concentration leads to the increase in current intensity. However, oxygen
present in the solution can react at some extent. When all the reaction sites for oxygen are occupied, the current
does not increase much as DO concentration increases. This leads to the observed saturation of the increase in
the current (Fig. 6 and Fig. 9).
IV. CONCLUSIONS
In this study we have investigated the DO sensitivity of the EB-PANI, ES-PANI and LEB-PANI films.
The UV-Vis spectra of the PANI solutions did not show any change in the presence of dissolved oxygen.
However, the CV measurements of the EB-PANI, ES-PANI and LEB-PANI films coated on the Pt electrodes
showed the increase in current as DO concentration in the solutions increased. The steep current increase of the
PANI films in the DO range of 1.5-10 ppm is suitable for monitoring of water quality in aquaculture farming.
The correlation of the current and DO concentrations was studied for the EB-PANI and LEB-PANI electrodes.
The higher DO sensitivity (3.35 µA/ppm) and higher stability of the LEB-PANI films enables the feasibility of
using LEB-PANI films as sensing materials in DO sensors.
V. ACKNOWLEDGMENTS
The authors highly appreciate the financial support of Vietnam National University - Ho Chi Minh City for this
study through the grant number B2013-76-04.
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