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Polyhydroxyalkanoates as potential tools for denitrification of wastewater
Denitrification is the main process in water and wastewater treatment which plays the critical role in mitigating nitrate contamination and ensuring environmental and public health safety. Introduction of polyhydroxyalkanoates (PHA) in water treatment systems enables widening of its application in denitrification processes. Emphasising the importance of denitrification in water treatment helps to prevent the surge of nitrate concentrations, thereby hindering eutrophication and maintaining the balance of aquatic ecosystems. Therefore, there is an increasing urgency for the development of sustainable and efficient denitrification techniques to address contemporary challenges in water quality management. PHAs are produced by a variety of microorganisms under limited nutritional conditions and present themselves as promising candidate for denitrification due to their favourable characteristics which include biocompatibility, biodegradability and ability to store carbon and energy. The current chapter delves with the mechanisms governing denitrification employing PHA along with the intricate biochemical pathways and metabolic processes involved. PHA serves a dual role as both a carbon source and an electron donor in denitrifying bacteria, aiding in the conversion of nitrate to nitrogen gas in anaerobic environments. The chapter furthermore addresses various factors such as substrate availability, microbial community composition, and environmental parameters which are affecting the efficiency of PHA-mediated denitrification. Despite the potential advantages, challenges impede the widespread adoption of PHA in denitrification processes. Technical constraints such as substrate availability, yield of PHA and reactor design, coupled with economic factors such as production costs, present significant barriers. Future research endeavours should prioritise optimising processes, surmounting technical and economic hurdles, and comprehending the ecological ramifications for water and wastewater treatment systems using PHA. Springer Nature Singapore Pte Ltd. 2025. All rights reserved. -
Polymer Nanocomposite Graphene Quantum Dots for High-Efficiency Ultraviolet Photodetector
Influence on photocurrent sensitivity of hydrothermally synthesized electrochemically active graphene quantum dots on conjugated polymer utilized for a novel single-layer device has been performed. Fabrications of high-performance ultraviolet photodetector by depositing the polypyrrole-graphene quantum dots (PPy-GQDs) active layer of the ITO electrode were exposed to an Ultraviolet (UV) source with 265 and 355 nm wavelengths for about 200 s, and we examined the time-dependent photoresponse. The excellent performance of GQDs was exploited as a light absorber, acting as an electron donor to improve the carrier concentration. PGC4 exhibits high photoresponsivity up to the 2.33 A/W at 6 V bias and the photocurrent changes from 2.9 to 18 A. The electrochemical measurement was studied using an electrochemical workstation. The cyclic voltammetry (CV) results show that the hysteresis loop is optically tunable with a UV light source with 265 and 355 nm at 0.1 to 0.5 V/s. The photocurrent response in PPy-GQDs devices may be applicable to optoelectronics devices. 2022 by the authors. -
Polymer photosupercapacitors: combined nanoarchitectonics with polymer solar cell and supercapacitor for emerging powerpacks in next-generation energy applications
Efficient energy harvesting and storage are inevitable for the sustenance and growth of mankind, wherein the utilization of advanced technologies in this field has brought a significant impact on the energy sector. Integration of energy harvesting and storage devices is a need for powering next-generation energy needs like the Internet of Things (IoT), opening a wide range of application areas like wearable devices or integration with fabrics. Among third-generation solar cells, organic or polymer solar cells are extremely environment-friendly, lightweight, and flexible, making themselves potential candidates for integrated powerpacks along with supercapacitors. This article is a comprehensive review of polymer solar cell-based photosupercapacitors and their developments over the recent years. Through this review, we intend to give a valid account of polymer photosupercapacitors, to the scientific community regarding recent updates, which would help develop future approaches and strategies. As these integrated devices are considered to have a profound impact on energy industries and related applications, we believe that a detailed review of the present status and future prospects would aid further developments in the research field. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024. -
Polymer-Based Nanomaterial as a Bacteriostatic Agent on Gram-Positive Bacteria
The colonization of surfaces by bacteria is a widespread phenomenon that affects environmental processes and human health. Bacterial growth can also be found in materials used in the textile industries, food packaging, and wearable electronics. Moreover, the necessity for replacing traditional antibiotics is relevant due to the increased health risks of antimicrobial resistance from the excessive use of antibiotics. Recently, research is focused more on developing polymer-based antibacterial materials critical to preventing bacterial proliferation. The use of some nanomaterials appears to be very promising in this regard. This work reports the synthesis of a polymer-based nanomaterial derived from polyvinyl alcohol (PVA) via the hydrothermal method and studies its structural and optical properties. It is also observed that these nanoparticles (NPs) display the highest antibacterial potency against gram-positive (Bacillus subtilis) bacteria than their bulk counterpart. 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. -
Polymer-Carbon nanocomposite: Synthesis, optical and biocidal properties
Microorganism contamination of food storage, water treatment, pharmaceuticals, and especially biomedical equipment is a severe problem. Bacteria frequently contaminate permanent implantations after long-term usage. To successfully treat these infections, it is essential to monitor microbial activity and know how it interacts with antibodies in real-time. In this work, a nanocarbon-polymer nanocomposite (ARPD) is successfully developed, and its antibacterial activity against selected microorganisms is successfully validated. Obtained antibacterial results confirm that the photoluminescent ARPD demonstrated outstanding antibacterial action against the microorganism Escherichia coli from the selected group of bacteria. The fluorescent diagnostics and treatments offer exciting possibilities for the luminescence and biocidal activity of nanocomposite produced from ARH-PVDF nanomaterials. 2023 The Author(s) -
Polymer-nanocarbon composites: a promising strategy for enhanced performance of organic solar cells
The exigency for sustainable and clean energy resources has led to profound research in development of various generations of solar cells, aiming to control the over-exploitation of fossil fuels and subsequently limit environmental degradation. Among the fast-emerging third-generation solar cells, polymer solar cell technology has gained much consideration due to its potential for achieving economically feasible, lightweight, flexible solar energy harvesting devices. As a predominant research area, at present, the major concerns regarding polymer solar cells include improving conversion efficiency, enhancing absorption bandgap in polymers, limiting photochemical degradation, and remediating low dielectric constant. Nanocarbon materials can be effectively blended with polymers and have been widely reported to enhance the performance of polymer solar cells owing to their desirable characteristics like high electrical conductivity, mechanical strength, thermal stability, non-toxicity, large specific surface area, flexibility, and optical transparency. In this review, we briefly discuss various conjugated polymer-nanocarbon composites, including polymer/graphene derivatives, polymer/graphene quantum dots (GQD), and polymer/carbon nanotubes (CNTs), elucidating their roles in the performance enhancement of polymer solar cells (PSCs). Graphical abstract: (Figure presented.). The Author(s) 2023. -
Polymeric Nanocomposites and Their Applications
A polymer is a macromolecule comprising numerous repeating subunits linked by covalent bonds. The word polymer arises from Greek, with polus denoting many and meros denoting parts. Although humans have used polymers long before, their chemical properties were studied only in the nineteenth century. The Author(s), under exclusive license to Springer Nature Switzerland AG 2025. -
Polynomial time algorithm for inferring subclasses of parallel internal column contextual array languages
In [2,16] a new method of description of pictures of digitized rectangular arrays is introduced based on contextual grammars, called parallel internal contextual array grammars. In this paper, we pay our attention on parallel internal column contextual array grammars and observe that the languages generated by these grammars are not inferable from positive data only. We define two subclasses of parallel internal column contextual array languages, namely, k-uniform and strictly parallel internal column contextual languages which are incomparable and not disjoint classes and provide identification algorithms to learn these classes. Springer International Publishing AG 2017. -
Polynomial time learner for inferring subclasses of internal contextual grammars with local maximum selectors
Natural languages contain regular, context-free, and context-sensitive syntactic constructions, yet none of these classes of formal languages can be identified in the limit from positive examples. Mildly context-sensitive languages are capable to represent some context-sensitive constructions such as multiple agreement, crossed agreement, and duplication. These languages are important for natural language applications due to their expressiveness, and the fact that they are not fully context-sensitive. In this paper, we present a polynomial-time algorithm for inferring subclasses of internal contextual languages using positive examples only, namely strictly and k-uniform internal contextual languages with local maximum selectors which can contain mildly context-sensitive languages. 2017, Springer International Publishing AG. -
Polyoxometalate/?-Fe2O3/polyaniline composite: Tailored approaches for high-performance supercapacitors
The need for portable, high-performance electronics that have high power or energy density has increased significantly in recent years. In this work, a composite material was coated on stainless steel that consists of polyoxometalate (POM)/?-Fe2O3/polyaniline (PANI) as an electrode material for a symmetric supercapacitor. ?-Fe2O3 was prepared using starch as a template while PANI was electrodeposited. The physical and chemical characteristics of the modified electrodes were investigated via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electrochemical techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge[sbnd]discharge (GCD) experiments. In 1 M H2SO4, the composite had a specific capacitance of 528 F/g at a current density of 0.2 A/g. In addition, the composite exhibited a high energy density of 73.4 Wh kg?1 at a high-power density of 7.14 kW kg?1 and 91.62 % capacity retention after 10 cycles. The results show that POM/?-Fe2O3/PANI is a promising composite electrode for use as a supercapacitor electrode material. 2024 The Authors -
Polyoxometalate/?-Fe2O3/polyaniline composite: Tailored approaches for high-performance supercapacitors
The need for portable, high-performance electronics that have high power or energy density has increased significantly in recent years. In this work, a composite material was coated on stainless steel that consists of polyoxometalate (POM)/?-Fe2O3/polyaniline (PANI) as an electrode material for a symmetric supercapacitor. ?-Fe2O3 was prepared using starch as a template while PANI was electrodeposited. The physical and chemical characteristics of the modified electrodes were investigated via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electrochemical techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge[sbnd]discharge (GCD) experiments. In 1 M H2SO4, the composite had a specific capacitance of 528 F/g at a current density of 0.2 A/g. In addition, the composite exhibited a high energy density of 73.4 Wh kg?1 at a high-power density of 7.14 kW kg?1 and 91.62 % capacity retention after 10 cycles. The results show that POM/?-Fe2O3/PANI is a promising composite electrode for use as a supercapacitor electrode material. 2024 The Authors -
Polyoxometalates and redox-active molecular clusters for supercapacitors
Hybrid electric vehicles and portable electronic devices become inevitable part of our daily life and it is necessary to develop efficient energy storage devices to supply them power. Supercapacitors (SCs) are electrochemical energy storage devices with high power densities. The electrochemical performances of a SC depend mainly on the electrode-active material used in it. An efficient electrode-active material should have qualities such as large surface area, porous structure, uniform pore distribution, good chemical and electrochemical stabilities, and good mechanical strength, to name a few. Mesoporous electrode architecture is highly preferred to obtain maximum electrolyte-ion accessibility that can boost the electrochemical performance of the SC electrode. The various electrode-active materials developed to date are transition metal oxides, electronically conducting polymers, carbon nanomaterials, etc. Polyoxometalates (POMs) are comparatively novel electrode candidates that possess excellent structural stability during the reversible redox reactions. A unique characteristic such as higher oxidation state possessed by POMs makes them an ideal platform to accept and release electrons during the electrochemical charge storage. POMs are considered to be a polyatomic anion, which hold early transition metals like Mo, V, W, etc., and are linked to an oxygen atom in a three-dimensional cluster. The cluster formation of POMs enables higher stability and easy to prepare composites with other materials such as carbon nanomaterial, electronically conducting polymers, etc. The preparation of hybrid electrode architectures by anchoring of POMs helps in producing a large number of electroactive sites for the enhanced electrochemical reactions to occur. This chapter explains the salient features and functionalities of POMs and redox-active molecular clusters that affect the SC performance. 2024 Elsevier Inc. All rights reserved. -
Polyphenol composition and antioxidant activity of andrographis paniculata L. nees /
Mapana Journal of Sciences, Vol.13, Issue 4, pp.481-494, ISSN No: 0975-3303 (Print) -
Polypyrrole functionalized MoS2 for sensitive and simultaneous determination of heavy metal ions in water
Assessing heavy metal ion (HMI) contamination to sustain drinking water hygiene is a challenge. Conventional approaches are appealing for the detection of HMIs but electrochemical approaches can resolve the limitations of these approaches, such as tedious sample preparation, high cost, time consuming and the need for trained professionals. Here, an electrochemical approach is developed using a nano-sphered polypyrrole (PPy) functionalized with MoS2 (PPy/MoS2) by square wave anodic stripping voltammetry for the detection of HMIs. The developed sensor can detect Pb2+ with a limit of detection of 0.03 nM and a sensitivity of 36.42 ?A nM?1. Additionally, the PPy/MoS2 sensor was employed for the simultaneous detection of HMIs of Cd2+, Pb2+, Cu2+ and Hg2+. The reproducibility, stability and anti-interference studies confirm that the sensor can be used to monitor HMI contamination of water. 2025 The Royal Society of Chemistry. -
Polypyrrole functionalized MoS2 for sensitive and simultaneous determination of heavy metal ions in water
Assessing heavy metal ion (HMI) contamination to sustain drinking water hygiene is a challenge. Conventional approaches are appealing for the detection of HMIs but electrochemical approaches can resolve the limitations of these approaches, such as tedious sample preparation, high cost, time consuming and the need for trained professionals. Here, an electrochemical approach is developed using a nano-sphered polypyrrole (PPy) functionalized with MoS2 (PPy/MoS2) by square wave anodic stripping voltammetry for the detection of HMIs. The developed sensor can detect Pb2+ with a limit of detection of 0.03 nM and a sensitivity of 36.42 ?A nM?1. Additionally, the PPy/MoS2 sensor was employed for the simultaneous detection of HMIs of Cd2+, Pb2+, Cu2+ and Hg2+. The reproducibility, stability and anti-interference studies confirm that the sensor can be used to monitor HMI contamination of water. 2025 The Royal Society of Chemistry. -
Polypyrrole- silver nanocomposite for enhanced photocatalytic degradation of methylene blue under sunlight irradiation
Polypyrrole (Ppy) -Silver nanocomposite samples have been synthesised by chemical oxidative polymerisation. The characteristic peaks of face centered cubic (fcc) structure of silver in XRD confirmed its presence in Ppy. Shift in NH stretching frequency observed in FTIR spectroscopy revealed the coordination of silver into Ppy. The photocatalytic activity of the samples was studied by photocatalytic degradation of the aqueous solution of methylene blue (MB) under sunlight. The presence of Ag in polypyrrole (Ppy) enhanced its photocatalytic activity with respect to the reported values which further increased on increasing the silver concentration. 2021 Elsevier B.V. -
Polypyrrole/ silver/graphene ternary nanocomposite synthesis and study on photocatalytic property in degrading Congo red dye under visible light
In this report, a simple chemical synthesis of polypyrrole/silver/graphene (Ppy/Ag/Gr) ternary nanocomposites with varying concentrations of graphene are described. The XRD spectra of the samples polypyrrole/silver (Ppy/Ag) and Ppy/Ag/Gr show all the peaks of the face-centered cubic structure of silver. A broad peak between 10 and 20 and a peak at 26.7 corresponds to Ppy and graphene respectively. Using FTIR, and UVVis. spectroscopies the interaction between polypyrrole, silver, and graphene were studied. In our work, we explored the photocatalytic property of the synthesised samples by using them to degrade the aqueous solution of a cancer-causing dye, Congo red. The percentage degradation of Congo red dye using the sample Ppy/Ag/Gr (0.5 wt.%) is obtained as 96% and the reaction rate calculated is 0.162/min., greater than that of Ppy/Ag and Ppy/Gr binary composites. Thus, the addition of the optimum concentration of graphene into Ppy/Ag enhanced its photocatalytic property. The BET analysis shows an increased surface area for the sample Ppy/Ag/Gr (0.5 wt.%) and the reason for the enhancement of photocatalysis with this sample is confirmed since it is a surface-dependent property. The biodegradability of the dye solution was investigated by Chemical Oxygen Demand (COD) analysis and the COD value was reduced from 432 mg/L to 216 mg/L after 20 min of irradiation of light. 2023 -
Polypyrrole/silver/graphene ternary composites for high-performance Ku-band electromagnetic interference shielding
Unwanted electromagnetic waves can significantly affect the performance of electronic devices and communication systems. A high-performance electromagnetic interference shielding (EMI) material is a solution to this issue. This study introduces a cost-effective one-pot synthesis method for polypyrrole/silver (Ppy/Ag), polypyrrole/graphene (Ppy/Gr) and polypyrrole/silver/graphene (Ppy/Ag/Gr) ternary composites with adjustable graphene concentrations. Detailed structural and morphological analyses using FTIR, XRD and STEM confirm the successful incorporation of Ag nanoparticles and graphene into the polypyrrole matrix. The total shielding effectiveness (SET) of the ternary composites in the Ku band shows an impressive 30.86 dB at 12.7 GHz for the 5 wt.% graphene composite, primarily driven by absorption mechanisms (SEA> SER). The synergistic interaction between Ag, which provides conductive pathways, and graphene, which offers structural reinforcement, significantly enhances interfacial polarisation and conductivity, surpassing the performance of binary counterparts (Ppy/Ag and Ppy/Gr. The results of this work introduce a lightweight, potent and economical composite material for EMI shielding applications in the Ku band. 2025 Elsevier B.V. -
Polyurethane nanocomposites for electromagnetic interference shielding applications
Polyurethane (PU) is composed of polyisocyanate and polyol units joined through urethane linkages. The isocyanate and polyol units constitute different domains in PU, which are, in turn, responsible for its properties such as softness, flexibility, and hardness. Shielding of electromagnetic (EM) radiation is generally attained by reflecting EM waves from the surface, absorbing the signals, or by multiple internal reflections. Pristine PU is not an efficient electromagnetic interference (EMI) shielding material because of its nonconducting nature. But the EMI shielding can be improved by incorporating conducting polymers into the PU-based nanocomposite. Significant factors that influence the shielding effect of PU nanocomposites are the thickness and conductivity of the film. Features that predominantly influence the EMI shielding performance of nanocomposites are identified as the nanofillers used, the dispersion state, and the interaction between the filler and the polymer. This book chapter attempts to explain the EMI shielding of PU nanocomposites, synthesis of PU-based EMI shielding materials, different nanofillers used along with PU nanocomposites, and their efficiency in EMI shielding. 2026 Elsevier Ltd. All rights reserved. -
Polyurethane nanocomposites for food packaging applications
Progress in food packaging technology improves modern food trade by simplifying transportation and sales, while offering enhanced protection. Traditional food packaging uses petroleum-based and nonbiodegradable packaging materials, leading to severe environmental and health-related issues. Polymer nanocomposites can reduce traditional plastic consumption and achieve a high recycling efficiency while maintaining the desired barrier and mechanical properties. Polyurethane, a polymer with good mechanical properties, is characterized by low pollution, easy modification, and environmental protection. Innovations in its structure and functionality through the incorporation of nanoscale fillers have led to enhanced barrier properties, thermal stability, and biodegradability. Polyurethane nanocomposites (PUNCs) exhibit multifunctional properties owing to the synergistic effect of polymers and nanofillers, and are used to increase the shelf life of food products, reducing food waste and foodborne illness, thereby contributing to sustainable development goals. This chapter begins by elucidating the fundamental properties of PU and the significance of various nanocomposites in tailoring these properties to fit packaging requirements. This chapter also describes the role of PUNCs in extending the shelf life of food, providing ultraviolet light protection, barrier, antimicrobial, and antioxidant properties, and enhancing the mechanical strength of packaging materials. The recent advancements in food packaging applications of PUNCs and the challenges and future perspectives related to large-scale production, consumer acceptability, recyclability, and potential health implication aspects are discussed in this chapter. 2026 Elsevier Ltd. All rights reserved.