Fahad Usman | Universiti Sains Malaysia (original) (raw)

Papers by Fahad Usman

Optik

Abstract An optical graphene-metal hybrid antenna geometry, permitting the efficient tuning of pl... more Abstract An optical graphene-metal hybrid antenna geometry, permitting the efficient tuning of plasmon resonance with unity absorption is reported. The total optical absorption and optical field enhancement are accomplished by designing a graphene-metal antenna. The antenna is comprised of gold hexagon radiator with bilayer graphene on the top, functioning as a double plasmonic resonant structure. The tunability of absorption and optical field enhancement is realized by electrical gating. The strong coupling takes place between the gold plasmons and graphene plasmons, resulting in the strong enhancement of optical fields. The proposed design is modelled in CST Microwave Studio and is simulated through FDTD solver. Moreover, the dynamic tuning of the resonance frequency and optical absorption is achieved by increasing the chemical potential of graphene layers through gate voltage. The tuning range of the designed antenna is optimized in a bandwidth starting from 30 THz to 34 THz. Although at 33 THz the antenna meets matching conditions by having high input impedance, low admittance, and almost unity absorption. The functioning bandwidth of the antenna is preferable for plasmonic applications i.e. infrared sensing and imaging, where high absorption and enhanced field characteristics are required.

Molecules

Presently, the rising concerns about the fossil fuel crisis and ecological deterioration have gre... more Presently, the rising concerns about the fossil fuel crisis and ecological deterioration have greatly affected the world economy and hence have attracted attention to the utilization of renewable energies. Among the renewable energy being developed, supercapacitors hold great promise in broad applications such as electric vehicles. Presently, the main challenge facing supercapacitors is the amount of energy stored. This, however, does not satisfy the increasing demand for higher energy storage devices, and therefore, intensive research is being undertaken to overcome the challenges of low energy density. The purpose of this review is to report on solid polymer electrolytes (SPEs) based on polyvinyl alcohol (PVA). The review discussed the PVA as a host polymer in SPEs followed by a discussion on the influence of conducting salts. The formation of SPEs as well as the ion transport mechanism in PVA SPEs were discussed. The application and development of PVA-based polymer electrolytes o...

Chemosensors

Kidney-related health problems cause millions of deaths around the world annually. Fortunately, m... more Kidney-related health problems cause millions of deaths around the world annually. Fortunately, most kidney problems are curable if detected at the earliest stage. Continuous monitoring of ammonia from exhaled breath is considered as a replacement for the conventional blood-based monitoring of chronic kidney disease (CKD) and kidney failure owing to its cost effectiveness, non-invasiveness, excellent sensitivity, and capabilities for real-time measurement. The detection of ammonia for renal failure requires a biosensor with a detection limit of 1000 ppb (1 ppm). Among biosensors, plasmonic biosensors have attracted considerable research interest due to their potential for ultra-sensitivity, single particle/molecular level detection capability, multiplexing capability, photostability, real-time measurement, label-free measurement, room temperature operation, naked-eye readability, ease of miniaturization via simple sensor chip fabrication, and instrumentation, among other features. I...

Groundwater for Sustainable Development

Sustainability

Clay minerals have been recognized as one of the cheap and effective materials for wastewater rem... more Clay minerals have been recognized as one of the cheap and effective materials for wastewater remediation. Among the various clay minerals, montmorillonite (MMT) has received much attention due to its wide availability, low-cost and promising properties such as high porosity, mechanical strength, and cation exchange capacity. Additionally, MMT has high swelling properties. These features make it an ideal material for wastewater remediation applications. In addition, it possessed good cationic exchange capacity, making it easier to interact with various molecules. MMT and its composites exhibited good selectivity and catalytic activity for contaminants elimination from wastewater. Surface modification and functionalization have been identified as a way to improve the MMT’s adsorptive performance and endow it with light and light-harnessing properties. Thus, MMT composites, especially metal and metal-oxide nanoparticles, have shown good adsorption and photocatalytic activity toward th...

Applied sciences, Sep 9, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Molecules

In this study, a solution casting method was used to prepare solid polymer electrolytes (SPEs) ba... more In this study, a solution casting method was used to prepare solid polymer electrolytes (SPEs) based on a polymer blend comprising polyvinyl alcohol (PVA), cellulose acetate (CA), and potassium carbonate (K2CO3) as a conducting salt, and zinc oxide nanoparticles (ZnO-NPs) as a nanofiller. The prepared electrolytes were physicochemically and electrochemically characterized, and their semi-crystalline nature was established using XRD and FESEM. The addition of ZnO to the polymer–salt combination resulted in a substantial increase in ionic conductivity, which was investigated using impedance analysis. The size of the semicircles in the Cole–Cole plots shrank as the amount of nanofiller increased, showing a decrease in bulk resistance that might be ascribed to an increase in ions due to the strong action of the ZnO-NPs. The sample with 10 wt % ZnO-NPs was found to produce the highest ionic conductivity, potential window, and lowest activation energy (Ea) of 3.70 × 10–3 Scm–1, 3.24 V, an...

Molecules

Successful synthesis of ZnO-chitosan nanocomposites was conducted for the removal of methylene bl... more Successful synthesis of ZnO-chitosan nanocomposites was conducted for the removal of methylene blue from an aqueous medium. Remarkable performance of the nanocomposites was demonstrated for the effective uptake of the dye, thereby achieving 83.77, 93.78 and 97.93 mg g−1 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. The corresponding adsorption efficiency was 88.77, 93.78 and 97.95 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. Upon regeneration, good reusability of the nanocomposites was manifested for the continuous removal of the dye up to six consecutive cycles. The adsorption process was kinetically described by a pseudo-first order model, while the isotherms were best fitted by the Langmuir model.

Diabetes is a disease that causes complications to human organs. It is currently diagnosed invasi... more Diabetes is a disease that causes complications to human organs. It is currently diagnosed invasively using blood glucose test. Fortunately, non-invasive diagnosis can be achieved through detection of acetone vapour due to its correlation with blood glucose where >1.8 ppm indicates diabetes. The widely investigated acetone vapour sensors based on metal oxide semiconductor (MOS) features high operational temperature, instability and cross-sensitivity. This work presents a non-invasive way of detecting acetone vapour using surface plasmon resonance (SPR) technique at room temperature. In order to evaluate the best acetone sensitive layer, p-toluene sulfonic acid doped polyaniline (PANI), PANI-chitosan composite, PANI-`reduced graphene oxide (RGO) composite, chitosan-polyethylene glycol (chitosan-PEG) and a ternary composite (comprising of PANI, reduced graphene oxide (RGO) and chitosan were synthesized and characterized using FTIR, UV-Vis, XPS, FESEM and AFM

Crystals, 2022

Worldwide, reservoirs are having serious challenges on crude oil removal due to various factors a... more Worldwide, reservoirs are having serious challenges on crude oil removal due to various factors affecting its mobility; hence, the approach of oil production needs to be rectified. Recently, various nanoparticles (NPs) were discovered to have aided in oil displacement to improve oil production by modifying some reservoir conditions thereby reducing interfacial tension (IFT) and rock surface wettability. However, the injected NPs in the reservoir are trapped within the rock pores and become worthless due to high temperature and pressure. Hence, introducing energy to the nanofluids via electromagnetic (EM) waves can improve nanoparticle (NPs) mobility in the reservoir for the attainment of oil displacements. In this work, hybrid ZnO/SiO2 NPs were selected by considering that the combination of two dielectric NPs may produce a single nanofluid that is expected to make the fluids more electrified under EM waves. The result showed that ZnO/SiO2 NPs reduced the IFT (mN/m) from 17.39 to 2....

Materials Today: Proceedings, 2022

Proceedings of the 6th International Conference on Fundamental and Applied Sciences, 2021

2020 8th International Conference on Intelligent and Advanced Systems (ICIAS), 2021

High rate of occurrences of cardiovascular diseases has led to development of devices and systems... more High rate of occurrences of cardiovascular diseases has led to development of devices and systems that can measure and detect early warning symptoms of abnormalities. Recent studies show that cardiovascular diseases are the topmost leading cause of death, thus we need to detect symptoms of these diseases before they deteriorate. There is a need to develop systems that will monitor cardiovascular properties such as pulse rate and blood oxygen concentration. This will be very useful to people at high risks of cardiovascular ilness. In this paper, sparse representation technique has been used to monitor the heart rate using IP camera. The PPG signal is used to estimate the physical parameters using non-invasive camera. The result is compared with existing dictionaries such as discrete wavelet transform and discrete cosine transform for sparse signal reconstruction. The results show that the proposed method produced better performance Signal-to-Noise Ratio (SNR) as compared to the start-of-the-art methods.

This work is aimed at evaluating the image reconstruction techniques used in single photon emissi... more This work is aimed at evaluating the image reconstruction techniques used in single photon emission computed tomography (SPECT/CT) imaging. The reconstruction techniques considered in this work are: the ordered subset expectation maximization (OSEM) and the Filtered Back Projection (FBP). An anthropomorphic torso phantom with lung and liver inserts was injected with 99mTc. The liver and the background were given 0.2 MBq/ml and 0.07 MBq/ml respectively. The lungs inserts were filled with polystyrene beads for humanization. A mimicked 30 ml tumor (27 mm) in the liver insert was given 2 MBq/ml sequential SPECT/CT (step and shot, 10 mins over 180° per head) and CT (120 kVp, 80 mAs) projections were acquired using dual head SPECT/16 slice CT system. The projections were reconstructed using OSEM (10 subsets for 2–10 numbers of iterations, Butterworth post filtering, 10 orders and 0.48 frequencies) and FBP (using Butterworth post filtering at 10 order and cutoff frequencies of 0.38–0.58, 0...

International Journal of Electrochemical Science, 2021

The advance of gel polymer electrolyte (GPEs) based on conducting salt-polymer has been a subject... more The advance of gel polymer electrolyte (GPEs) based on conducting salt-polymer has been a subject of concern recently due to their significant applications. This work presents a study of dielectric properties of GPE based on polyvinyl alcohol (PVA) and potassium carbonate (K2CO3) (PVA-K2CO3) electrolyte for electrochemical applications. The electrolyte material was synthesized by mixing a conducting salt (K2CO3) with PVA in different proportions (from 10-50 wt. %) in order to study the effect of the salt on the dielectric properties of the electrolyte. The synthesized GPE was characterized using X-ray powder diffraction (XRD) to study electrolyte's crystal phase. Both complex permittivity and complex modulus formalism (dielectric behaviour) of the electrolyte were analysed through electrochemical impedance spectroscopy (EIS). The characterization result shows that the peak intensity of the PVA is significantly reduced with the increase of K2CO3 wt.%. which could be attributed to the decrease of PVA crystallinity which can enlarge the amorphous region of the polymer due to the strong plasticizing effect of the salt. High values of complex permittivity (dielectric constant and dielectric loss) were observed at low frequencies, which increased with increasing temperature, indicating an increase in conductivity. From the real part of electric modulus, the material is featured to be highly capacitive. Based on the asymmetrical peak shape of the imaginary part of electric modulus, the non-Debye type relaxation is predicted. Straight-line graphs were observed from the frequency dependency of loss tangent (tan δ), showing no single relaxation process is present.

Polymers, 2020

This work reports the use of a ternary composite that integrates p-Toluene sulfonic acid doped po... more This work reports the use of a ternary composite that integrates p-Toluene sulfonic acid doped polyaniline (PANI), chitosan, and reduced graphene oxide (RGO) as the active sensing layer of a surface plasmon resonance (SPR) sensor. The SPR sensor is intended for application in the non-invasive monitoring and screening of diabetes through the detection of low concentrations of acetone vapour of less than or equal to 5 ppm, which falls within the range of breath acetone concentration in diabetic patients. The ternary composite film was spin-coated on a 50-nm-thick gold layer at 6000 rpm for 30 s. The structure, morphology and chemical composition of the ternary composite samples were characterized by FTIR, UV-VIS, FESEM, EDX, AFM, XPS, and TGA and the response to acetone vapour at different concentrations in the range of 0.5 ppm to 5 ppm was measured at room temperature using SPR technique. The ternary composite-based SPR sensor showed good sensitivity and linearity towards acetone vap...

Journal of Cleaner Production, 2019

Recently, the conversion of palm waste to activated carbon for various applications has attracted... more Recently, the conversion of palm waste to activated carbon for various applications has attracted significant attention from researchers. Over the years, abundant palm wastes have been produced due to active palm milling in various part of the world. These environmentally challenging wastes have been converted to valuable and economical materials for gas adsorption and water treatment but rarely for energy storage application. The lignocellulose composition of palm wastes has made it a favorable candidate for starting material of activated carbon for supercapacitor application. In this review, the pretreatment condition, factors to consider for choosing starting material, activation techniques, and activation parameters such as activation temperature, activation time, activation agent and impregnation ratio are analyzed. The advantages of the synergistic effect of the lignocellulose composition of different palm wastes for energy storage device is discussed. The major drawbacks in the conventional Barrett-Joiner-Halenda (BJH) porosity characterization technique are addressed and the novel Non-localized Density Functional Theory characterization technique is suggested. Conclusively, future prospects in the activation of palm bio-wastes for supercapacitor application are highlighted. HIGHLIGHTS Promises and prospects of exploration of palm wastes for energy storage Advances in analysis and characterization techniques of the porosity of activated carbons Optimization techniques of pretreatment and preparatory conditions of activated carbon Relevancies of heat kinetics in improving biomass activation Palm waste optimization technique for activated carbon production application.

Optik

Abstract An optical graphene-metal hybrid antenna geometry, permitting the efficient tuning of pl... more Abstract An optical graphene-metal hybrid antenna geometry, permitting the efficient tuning of plasmon resonance with unity absorption is reported. The total optical absorption and optical field enhancement are accomplished by designing a graphene-metal antenna. The antenna is comprised of gold hexagon radiator with bilayer graphene on the top, functioning as a double plasmonic resonant structure. The tunability of absorption and optical field enhancement is realized by electrical gating. The strong coupling takes place between the gold plasmons and graphene plasmons, resulting in the strong enhancement of optical fields. The proposed design is modelled in CST Microwave Studio and is simulated through FDTD solver. Moreover, the dynamic tuning of the resonance frequency and optical absorption is achieved by increasing the chemical potential of graphene layers through gate voltage. The tuning range of the designed antenna is optimized in a bandwidth starting from 30 THz to 34 THz. Although at 33 THz the antenna meets matching conditions by having high input impedance, low admittance, and almost unity absorption. The functioning bandwidth of the antenna is preferable for plasmonic applications i.e. infrared sensing and imaging, where high absorption and enhanced field characteristics are required.

Molecules

Presently, the rising concerns about the fossil fuel crisis and ecological deterioration have gre... more Presently, the rising concerns about the fossil fuel crisis and ecological deterioration have greatly affected the world economy and hence have attracted attention to the utilization of renewable energies. Among the renewable energy being developed, supercapacitors hold great promise in broad applications such as electric vehicles. Presently, the main challenge facing supercapacitors is the amount of energy stored. This, however, does not satisfy the increasing demand for higher energy storage devices, and therefore, intensive research is being undertaken to overcome the challenges of low energy density. The purpose of this review is to report on solid polymer electrolytes (SPEs) based on polyvinyl alcohol (PVA). The review discussed the PVA as a host polymer in SPEs followed by a discussion on the influence of conducting salts. The formation of SPEs as well as the ion transport mechanism in PVA SPEs were discussed. The application and development of PVA-based polymer electrolytes o...

Chemosensors

Kidney-related health problems cause millions of deaths around the world annually. Fortunately, m... more Kidney-related health problems cause millions of deaths around the world annually. Fortunately, most kidney problems are curable if detected at the earliest stage. Continuous monitoring of ammonia from exhaled breath is considered as a replacement for the conventional blood-based monitoring of chronic kidney disease (CKD) and kidney failure owing to its cost effectiveness, non-invasiveness, excellent sensitivity, and capabilities for real-time measurement. The detection of ammonia for renal failure requires a biosensor with a detection limit of 1000 ppb (1 ppm). Among biosensors, plasmonic biosensors have attracted considerable research interest due to their potential for ultra-sensitivity, single particle/molecular level detection capability, multiplexing capability, photostability, real-time measurement, label-free measurement, room temperature operation, naked-eye readability, ease of miniaturization via simple sensor chip fabrication, and instrumentation, among other features. I...

Groundwater for Sustainable Development

Sustainability

Clay minerals have been recognized as one of the cheap and effective materials for wastewater rem... more Clay minerals have been recognized as one of the cheap and effective materials for wastewater remediation. Among the various clay minerals, montmorillonite (MMT) has received much attention due to its wide availability, low-cost and promising properties such as high porosity, mechanical strength, and cation exchange capacity. Additionally, MMT has high swelling properties. These features make it an ideal material for wastewater remediation applications. In addition, it possessed good cationic exchange capacity, making it easier to interact with various molecules. MMT and its composites exhibited good selectivity and catalytic activity for contaminants elimination from wastewater. Surface modification and functionalization have been identified as a way to improve the MMT’s adsorptive performance and endow it with light and light-harnessing properties. Thus, MMT composites, especially metal and metal-oxide nanoparticles, have shown good adsorption and photocatalytic activity toward th...

Applied sciences, Sep 9, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Molecules

In this study, a solution casting method was used to prepare solid polymer electrolytes (SPEs) ba... more In this study, a solution casting method was used to prepare solid polymer electrolytes (SPEs) based on a polymer blend comprising polyvinyl alcohol (PVA), cellulose acetate (CA), and potassium carbonate (K2CO3) as a conducting salt, and zinc oxide nanoparticles (ZnO-NPs) as a nanofiller. The prepared electrolytes were physicochemically and electrochemically characterized, and their semi-crystalline nature was established using XRD and FESEM. The addition of ZnO to the polymer–salt combination resulted in a substantial increase in ionic conductivity, which was investigated using impedance analysis. The size of the semicircles in the Cole–Cole plots shrank as the amount of nanofiller increased, showing a decrease in bulk resistance that might be ascribed to an increase in ions due to the strong action of the ZnO-NPs. The sample with 10 wt % ZnO-NPs was found to produce the highest ionic conductivity, potential window, and lowest activation energy (Ea) of 3.70 × 10–3 Scm–1, 3.24 V, an...

Molecules

Successful synthesis of ZnO-chitosan nanocomposites was conducted for the removal of methylene bl... more Successful synthesis of ZnO-chitosan nanocomposites was conducted for the removal of methylene blue from an aqueous medium. Remarkable performance of the nanocomposites was demonstrated for the effective uptake of the dye, thereby achieving 83.77, 93.78 and 97.93 mg g−1 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. The corresponding adsorption efficiency was 88.77, 93.78 and 97.95 for the chitosan, 5 wt.% ZnO-Chitosan and 10 wt.% ZnO-Chitosan, respectively. Upon regeneration, good reusability of the nanocomposites was manifested for the continuous removal of the dye up to six consecutive cycles. The adsorption process was kinetically described by a pseudo-first order model, while the isotherms were best fitted by the Langmuir model.

Diabetes is a disease that causes complications to human organs. It is currently diagnosed invasi... more Diabetes is a disease that causes complications to human organs. It is currently diagnosed invasively using blood glucose test. Fortunately, non-invasive diagnosis can be achieved through detection of acetone vapour due to its correlation with blood glucose where >1.8 ppm indicates diabetes. The widely investigated acetone vapour sensors based on metal oxide semiconductor (MOS) features high operational temperature, instability and cross-sensitivity. This work presents a non-invasive way of detecting acetone vapour using surface plasmon resonance (SPR) technique at room temperature. In order to evaluate the best acetone sensitive layer, p-toluene sulfonic acid doped polyaniline (PANI), PANI-chitosan composite, PANI-`reduced graphene oxide (RGO) composite, chitosan-polyethylene glycol (chitosan-PEG) and a ternary composite (comprising of PANI, reduced graphene oxide (RGO) and chitosan were synthesized and characterized using FTIR, UV-Vis, XPS, FESEM and AFM

Crystals, 2022

Worldwide, reservoirs are having serious challenges on crude oil removal due to various factors a... more Worldwide, reservoirs are having serious challenges on crude oil removal due to various factors affecting its mobility; hence, the approach of oil production needs to be rectified. Recently, various nanoparticles (NPs) were discovered to have aided in oil displacement to improve oil production by modifying some reservoir conditions thereby reducing interfacial tension (IFT) and rock surface wettability. However, the injected NPs in the reservoir are trapped within the rock pores and become worthless due to high temperature and pressure. Hence, introducing energy to the nanofluids via electromagnetic (EM) waves can improve nanoparticle (NPs) mobility in the reservoir for the attainment of oil displacements. In this work, hybrid ZnO/SiO2 NPs were selected by considering that the combination of two dielectric NPs may produce a single nanofluid that is expected to make the fluids more electrified under EM waves. The result showed that ZnO/SiO2 NPs reduced the IFT (mN/m) from 17.39 to 2....

Materials Today: Proceedings, 2022

Proceedings of the 6th International Conference on Fundamental and Applied Sciences, 2021

2020 8th International Conference on Intelligent and Advanced Systems (ICIAS), 2021

High rate of occurrences of cardiovascular diseases has led to development of devices and systems... more High rate of occurrences of cardiovascular diseases has led to development of devices and systems that can measure and detect early warning symptoms of abnormalities. Recent studies show that cardiovascular diseases are the topmost leading cause of death, thus we need to detect symptoms of these diseases before they deteriorate. There is a need to develop systems that will monitor cardiovascular properties such as pulse rate and blood oxygen concentration. This will be very useful to people at high risks of cardiovascular ilness. In this paper, sparse representation technique has been used to monitor the heart rate using IP camera. The PPG signal is used to estimate the physical parameters using non-invasive camera. The result is compared with existing dictionaries such as discrete wavelet transform and discrete cosine transform for sparse signal reconstruction. The results show that the proposed method produced better performance Signal-to-Noise Ratio (SNR) as compared to the start-of-the-art methods.

This work is aimed at evaluating the image reconstruction techniques used in single photon emissi... more This work is aimed at evaluating the image reconstruction techniques used in single photon emission computed tomography (SPECT/CT) imaging. The reconstruction techniques considered in this work are: the ordered subset expectation maximization (OSEM) and the Filtered Back Projection (FBP). An anthropomorphic torso phantom with lung and liver inserts was injected with 99mTc. The liver and the background were given 0.2 MBq/ml and 0.07 MBq/ml respectively. The lungs inserts were filled with polystyrene beads for humanization. A mimicked 30 ml tumor (27 mm) in the liver insert was given 2 MBq/ml sequential SPECT/CT (step and shot, 10 mins over 180° per head) and CT (120 kVp, 80 mAs) projections were acquired using dual head SPECT/16 slice CT system. The projections were reconstructed using OSEM (10 subsets for 2–10 numbers of iterations, Butterworth post filtering, 10 orders and 0.48 frequencies) and FBP (using Butterworth post filtering at 10 order and cutoff frequencies of 0.38–0.58, 0...

International Journal of Electrochemical Science, 2021

The advance of gel polymer electrolyte (GPEs) based on conducting salt-polymer has been a subject... more The advance of gel polymer electrolyte (GPEs) based on conducting salt-polymer has been a subject of concern recently due to their significant applications. This work presents a study of dielectric properties of GPE based on polyvinyl alcohol (PVA) and potassium carbonate (K2CO3) (PVA-K2CO3) electrolyte for electrochemical applications. The electrolyte material was synthesized by mixing a conducting salt (K2CO3) with PVA in different proportions (from 10-50 wt. %) in order to study the effect of the salt on the dielectric properties of the electrolyte. The synthesized GPE was characterized using X-ray powder diffraction (XRD) to study electrolyte's crystal phase. Both complex permittivity and complex modulus formalism (dielectric behaviour) of the electrolyte were analysed through electrochemical impedance spectroscopy (EIS). The characterization result shows that the peak intensity of the PVA is significantly reduced with the increase of K2CO3 wt.%. which could be attributed to the decrease of PVA crystallinity which can enlarge the amorphous region of the polymer due to the strong plasticizing effect of the salt. High values of complex permittivity (dielectric constant and dielectric loss) were observed at low frequencies, which increased with increasing temperature, indicating an increase in conductivity. From the real part of electric modulus, the material is featured to be highly capacitive. Based on the asymmetrical peak shape of the imaginary part of electric modulus, the non-Debye type relaxation is predicted. Straight-line graphs were observed from the frequency dependency of loss tangent (tan δ), showing no single relaxation process is present.

Polymers, 2020

This work reports the use of a ternary composite that integrates p-Toluene sulfonic acid doped po... more This work reports the use of a ternary composite that integrates p-Toluene sulfonic acid doped polyaniline (PANI), chitosan, and reduced graphene oxide (RGO) as the active sensing layer of a surface plasmon resonance (SPR) sensor. The SPR sensor is intended for application in the non-invasive monitoring and screening of diabetes through the detection of low concentrations of acetone vapour of less than or equal to 5 ppm, which falls within the range of breath acetone concentration in diabetic patients. The ternary composite film was spin-coated on a 50-nm-thick gold layer at 6000 rpm for 30 s. The structure, morphology and chemical composition of the ternary composite samples were characterized by FTIR, UV-VIS, FESEM, EDX, AFM, XPS, and TGA and the response to acetone vapour at different concentrations in the range of 0.5 ppm to 5 ppm was measured at room temperature using SPR technique. The ternary composite-based SPR sensor showed good sensitivity and linearity towards acetone vap...

Journal of Cleaner Production, 2019

Recently, the conversion of palm waste to activated carbon for various applications has attracted... more Recently, the conversion of palm waste to activated carbon for various applications has attracted significant attention from researchers. Over the years, abundant palm wastes have been produced due to active palm milling in various part of the world. These environmentally challenging wastes have been converted to valuable and economical materials for gas adsorption and water treatment but rarely for energy storage application. The lignocellulose composition of palm wastes has made it a favorable candidate for starting material of activated carbon for supercapacitor application. In this review, the pretreatment condition, factors to consider for choosing starting material, activation techniques, and activation parameters such as activation temperature, activation time, activation agent and impregnation ratio are analyzed. The advantages of the synergistic effect of the lignocellulose composition of different palm wastes for energy storage device is discussed. The major drawbacks in the conventional Barrett-Joiner-Halenda (BJH) porosity characterization technique are addressed and the novel Non-localized Density Functional Theory characterization technique is suggested. Conclusively, future prospects in the activation of palm bio-wastes for supercapacitor application are highlighted. HIGHLIGHTS Promises and prospects of exploration of palm wastes for energy storage Advances in analysis and characterization techniques of the porosity of activated carbons Optimization techniques of pretreatment and preparatory conditions of activated carbon Relevancies of heat kinetics in improving biomass activation Palm waste optimization technique for activated carbon production application.