Browsing by Author "Ravindra Kumar Gautam"

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2D hexagonal boron nitride nanosheets supported with palladium-doped zinc oxide nanoparticle–based electrochemical sensor for the detection of indole- 3-acetic acid
(Springer Science and Business Media Deutschland GmbH, 2025) Jyoti Prajapati; Ashish Gupta; Ravindra Kumar Gautam; Jaya Joshi; Nishi Kumari; I. C. Tiwari
Indole- 3-acetic acid (IAA) plays major role in stress responses and plant defense against pathogens. When a plant is under stress, such as when it is exposed to high temperature or drought conditions, the levels of IAA increases, which triggers a range of responses that helps the plant to cope with the stress. In this study, we developed electrochemical sensor based on nanocomposite of palladium-doped zinc oxide and 2D hexagonal boron nitride (Pd-ZnO/h-BN) for effective electrochemical detection of IAA. The structural and morphological structure of the Pd-ZnO/h-BN nanocomposite was investigated using a variety of characterization techniques, FT-IR, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM), transmission electron spectroscopy (TEM), electrochemical impedance spectroscopy(EIS), and chronoamperometry techniques were used for quantitative analysis of IAA. The sensing capability of the Pd-ZnO/h-BN modified glassy carbon electrode (GCE) for IAA detection was evaluated utilizing cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Because of its multiple active sites, rapid charge transfer, and abundance of defects, the Pd-ZnO/h-BN/GCE exhibits a synergetic catalytic impact on IAA oxidation. The suggested electrochemical sensor has a low detection limit (LOD) for IAA is 0.13 µM using DPV and 0.21 µM using CV, good linear ranges (0.5 to 50 µM), and high sensitivity (0.2407 µA cm−2 µM−1). This fabricated sensor shows excellent real time analysis towards IAA in the seedling extract of Vigna radiata and Triticum aestivum. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
A highly efficient NiCo2O4 decorated g-C3N4 nanocomposite for screen-printed carbon electrode based electrochemical sensing and adsorptive removal of fast green dye
(Springer, 2024) Ankit Kumar Singh; Shreanshi Agrahari; Ravindra Kumar Gautam; Ida Tiwari
Herein, we demonstrate the preparation and application of NiCo2O4 decorated over a g-C3N4-based novel nanocomposite (NiCo2O4@g-C3N4). The prepared material was well characterized through several physicochemical techniques, including FT-IR, XRD, SEM, and TEM. The electrochemical characterizations via electrochemical impedance spectroscopy show the low electron transfer resistance of NiCo2O4@g-C3N4 owing to the successful incorporation of NiCo2O4 nanoparticles on the sheets of g-C3N4. NiCo2O4@g-C3N4 nanocomposite was employed in the fabrication of a screen-printed carbon electrode-based innovative electrochemical sensing platform and the adsorptive removal of a food dye, i.e., fast green FCF dye (FGD). The electrochemical oxidation of FGD at the developed NiCo2O4@g-C3N4 nanocomposite modified screen-printed carbon electrode (NiCo2O4@g-C3N4/SPCE) was observed at an oxidation potential of 0.65 V. A wide dual calibration range for electrochemical determination of FGD was successfully established at the prepared sensing platform, showing an excellent LOD of 0.13 µM and sensitivity of 0.6912 µA.µM−1.cm−2 through differential pulse voltammetry. Further, adsorbent dose, pH, contact time, and temperature were optimized to study the adsorption phenomena. The adsorption thermodynamics, isotherm, and kinetics were also investigated for efficient removal of FGD at NiCo2O4@g-C3N4-based adsorbents. The adsorption phenomenon of FGD on NiCo2O4@g-C3N4 was best fitted (R2 = 0.99) with the Langmuir and Henry model, and the corresponding value of Langmuir adsorption efficiency (qm) was 3.72 mg/g for the removal of FGD. The reaction kinetics for adsorption phenomenon were observed to be pseudo-second order. The sensitive analysis of FGD in a real sample was also studied. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.
Answer to comments on: ‘Voltammetric analysis of epinephrine using glassy carbon electrode modified with nanocomposite prepared from Co-Nd bimetallic nanoparticles, alumina nanoparticles and functionalized multiwalled carbon nanotubes’ by Ida Tiwari et al., (Doi: 10.1007/s11356-022–23660-y)
(Springer Science and Business Media Deutschland GmbH, 2023) Shreanshi Agrahari; Ankit Kumar Singh; Ravindra Kumar Gautam; Ida Tiwari
This is an answer to the letter by the editor that was sent in response to our previously published article entitled “Voltammetric analysis of epinephrine using glassy carbon electrode modified with nanocomposite prepared from Co-Nd bimetallic nanoparticles, alumina nanoparticles and functionalized multiwalled carbon nanotubes." We are grateful to the writers for showing an interest in our manuscript and for providing such helpful feedback. We emphasise that our research was just a preliminary investigation to detect epinephrine in different biological samples, however, in literature a link between epinephrine and acute respiratory distress syndrome (ARDS) is already reported. Hence, we are agreeing to the authors that epinephrine is suggested as a cause for ARDS following anaphylaxis. It is recommended that more research be carried out to evaluate the possibility of epinephrine as a cause for ARDS and to validate the therapeutic relevance of the findings. Additionally, the purpose of our research was electrochemical sensing of epinephrine alternative to the conventional means like HPLC, fluorimetry, etc. for epinephrine detection. We have found that benefits which the electrochemical sensors have, are their simplicity, cost-effectiveness, ease of use owing to their small size, mass manufacture, and straightforward operation, as well as their extreme sensitivity and selectivity, hence the electrochemical sensing methods are more beneficial than conventional techniques for epinephrine analysis. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Antibacterial activity of green-synthesized silver nanoparticles
(Elsevier, 2024) Ashish Gupta; Brajesh Chandra Pandey; Ravindra Kumar Gautam; Ida Tiwari; Nishi Kumari
Recently, silver nanoparticles (AgNPs) are gaining attention due to their enhanced application in various fields such as biomedicine, biotechnology, bioengineering, and water treatment. Significant antibacterial, anticancer, and cytotoxic activities shown by them enhance their potential for medical applications. Their synthesis is possible through chemical, physical, and biological means, but first two methods are time-consuming and costly. Chemical synthesis of AgNPs has major drawback, as through this method sometimes toxic chemical is released. Biological synthesis or green synthesis of AgNPs uses microorganisms or plant extracts as raw materials. Plants are considered as natural reservoir of diverse types of chemicals. As different plants have different types and concentrations of phytochemicals, therefore, AgNPs prepared from different plant sources display different properties of nanoparticles. Biological method is considered as cost-effective and eco-friendly, and less time is required in this method. The biosynthesized AgNPs are being characterized by different methods such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. AgNPs have shown significant inhibition activities against several bacterial and fungal strains. Their interactions with microbes cause structural damage to microbial cell wall, thus making it as potent and efficient alternative of antimicrobials. Therefore, handling of antibiotic resistance of several bacteria will be possible either by using AgNPs alone or in combination with antibiotics. © 2025 Elsevier Ltd. All rights reserved.
Biochar for remediation of agrochemicals and synthetic organic dyes from environmental samples: A review
(Elsevier Ltd, 2021) Ravindra Kumar Gautam; Mandavi Goswami; Rakesh K. Mishra; Preeti Chaturvedi; Mukesh Kumar Awashthi; Ram Sharan Singh; Balendu Shekhar Giri; Ashok Pandey
Application of agrochemicals in farming sector to control insects and pests; and use of synthetic organic dyes to color the products are increasing continuously due to the rapid growth of industries. During the application process many industries releases toxic agrochemicals and dyes in to the aquatic environment and on land without the proper treatment. Due to their toxicity the disposal of such chemicals is of utmost importance. Biochar offers the ability to remediate these substances from environmental matrices because of their high sorption ability of pollutants from water and soil. This review highlights the development and advancement of biochar-based treatment for abatement of agrochemicals and synthetic organic dyes, involving its technical aspects and the variables connected with removing these kinds of pollutants. Several optimization parameters like temperature, pH, chemical concentration, biochar properties, time, and co-existing ions have been elaborated. Literature survey shows that most of the researches on biochar application have been conducted in the batch mode. Hence there is an urgent need to apply this beneficial technique for the remediation of pollutants at the larger scale in the real water and soil samples. A comprehensive summary on sorption kinetics and adsorption isotherms with regards to pollutant removal is also presented. This review also covers the cost analysis of various techniques where biochar has been used as an adsorbent. Thus this review makes an easy roadmap for the further development in biochar and biochar based composites and expansion of these demanding areas of research in biochar and their applications. © 2021
Copper-doped titanium dioxide nanoparticles decorated on 2D-hexagonal boron nitride nanosheets for susceptible electrochemical detection of an anti-cancer drug in environmental and biological samples
(Springer, 2024) Jyoti Prajapati; Ravindra Kumar Gautam; Ida Tiwari
Chlorambucil (CML) cures chronic lymphatic leukemia (white blood cell cancer). A high dose of CML can cause several side effects like bone marrow suppression, anemia, peripheral neuropathy, and infertility in the human body. In this research, we have synthesized a nanocomposite based on copper-doped titanium dioxide (CuTiO2) adorned with 2D hexagonal boron nitride (CuTiO2@BN) for the efficient electrochemical detection of CML. A series of characterization techniques FT-IR, XRD, Raman spectroscopy, SEM, TEM, EDAX XPS, and electrochemical characterization were used to analyze the CuTiO2@BN nanocomposite structural and morphological compositions. The sensing performance of the CuTiO2@BN modified GCE for CML detection has been assessed using voltammetry methods. The chronoamperometry technique analyzed the kinetics of the electrochemical oxidation of CML at CuTiO2@BN/GCE. The CuTiO2@BN-based glassy carbon electrode (GCE) has a synergetic electro-catalytic effect on CML oxidation due to its many active sites, enhanced surface area, fast charge transfer, and numerous defects. For the detection of CML, the suggested electrochemical sensor exhibits excellent selectivity, low limit of detection (LOD) as found 5.0 nM, wide linear ranges (0.02–8000 µM), and quick reaction times. Graphical Abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.
Development of g-C3N4/Cu-DTO MOF nanocomposite based electrochemical sensor towards sensitive determination of an endocrine disruptor BPSIP
(Elsevier B.V., 2021) Ankit Kumar Singh; Nandita Jaiswal; Ravindra Kumar Gautam; Ida Tiwari
In the present study, we successfully synthesized graphitic carbon nitride (g-C3N4) and functionalized with copper coordinated dithiooxamide metal organic framework (Cu-DTO MOF) to form g-C3N4/Cu-DTO MOF nanocomposite. The synthesized g-C3N4 and g-C3N4/Cu-DTO MOF nanocomposite were thoroughly characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). The TEM analysis of g-C3N4/Cu-DTO MOF composite material shows the successful immobilization of Cu-DTO MOF particles on the platform of g-C3N4 flakes. The electrochemical sensing performance of g-C3N4 and g-C3N4/Cu-DTO MOF nanocomposite modified electrodes were compared through sensitive determination of an endocrine disruptor i.e., 4-(4-isopropoxy-benzenesulfonyl)-phenol (BPSIP) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The detection limit was estimated to be 0.02 µM and sensitivity to be 0.5675 µAµM-1cm−2 for the proposed g-C3N4/Cu-DTO MOF nanocomposite based BPSIP sensor through DPV that are better as compared to g-C3N4 based sensor. Therefore, it was found that the nanocomposite based sensor has better sensing ability and was successfully applied for the determination of BPSIP in river water sample. © 2021 Elsevier B.V.
Electrochemical Methods for the Detection of Pharmaceutical Residues in Environmental Samples
(CRC Press, 2023) Shreanshi Agrahari; Ankit Kumar Singh; Ravindra Kumar Gautam; Ida Tiwari
In the last decades, pharmaceutical residues have gained increased attention due to their harmful impacts on the environment, owing to their pseudo-persistent nature. Further, they act as potentially active toxic biochemicals present at trace levels (i.e., µg/L or ng/L), which cause long-term impacts both on human and animal welfare. Several techniques have been reported for detecting pharmaceutical residues, including HPLC, GC, LC/MS, GC/MS, optical techniques, immunoassay tests, NMR, Raman spectroscopy, etc. These approaches are expensive; time-consuming; need pre-sample preparation, extraction, purification; and require particular biomolecules (antibodies, antigens, enzymes) for analysis. Electrochemical methods are selective and sensitive and can detect low amounts of pharmaceutical residues in the environment owing to their efficiency, speed, cost-effective manufacturing, and short analysis time. Moreover, electrochemical methods provide quick on-site monitoring of pharmaceutical residues existing in the environment, owing to easy monitoring and automation. © 2024 selection and editorial matter, Vinod Kumar Garg, Ashok Pandey, Navish Kataria, and Caterina Faggio; individual chapters, the contributors.
Electrochemical oxidation and sensing of para benzoquinone using a novel SPE based disposable sensor
(Elsevier Ltd, 2023) Shreanshi Agrahari; Ankit Kumar Singh; Ravindra Kumar Gautam; Ida Tiwari
Para-benzoquinone (PBQ) is an emerging micro-contaminant owing to its chronic toxicity to plants and animals as well as its potential to induce cytotoxicity in primary rat hepatocytes and kidney cell injury. Hence, it is of utmost importance to monitor this contaminant in industrial wastewater and groundwater. In this article, we devised a unique disposable sensor that is based on a screen-printed electrode using MnO2@Co–Ni MOFs/fMWCNTs nanocomposite and is able to detect PBQ. The as-produced nanocomposite was prepared via ultrasonic assisted reflux condition and thoroughly examined by several physicochemical characterisation methods such as SEM, EDX, TEM, Raman, AFM, UV–visible, and FT-IR. Moreover, electrochemical methods like CV, DPV, EIS, and chronoamperometry were used for detecting PBQ on MnO2@Co–Ni MOFs/fMWCNTs/SPCE. Sensor performance has been investigated thoroughly and optimized to enhance the analytical potential of the fabricated sensor. DPV analysis was done on MnO2@Co–Ni MOFs/fMWCNTs that exhibit high selectivity, low peak potential, a broader linear detection range (0.005 mM–30 mM), and a LOD of 0.0027 ± 0.0005 mM. The designed electrode has shown remarkable reproducibility and excellent repeatability, with relative standard deviations of 0.12%, and 0.17%, respectively. Additionally, MnO2@Co–Ni MOFs/fMWCNTs/SPCE have been used to analyse PBQ in industrial wastewater samples, and the results have shown a significant level of recovery between 96.91 and 105.67%. Moreover, the PBQ sensor displays high applicability and was verified via the use of HPLC techniques. This disposable sensor is quick, easy, and cost-effective, so it can be useful in the future for analysing other phenolic contaminants present in environmental samples. © 2023 Elsevier Ltd
Electrochemical Sensing and Biomedical Applications of Green Nanomaterials
(Springer International Publishing, 2023) Ankit Kumar Singh; Ravindra Kumar Gautam; Shreanshi Agrahari; Ida Tiwari
Nanomaterials are used in a variety of fields, including agriculture, food technology, textiles, waste water treatment, cosmetics, sports goods, purification techniques, and medications, due to their huge surface area-to-volume ratio and size-dependent qualities. These nanomaterials are used in almost every aspect of life, yet there are safety concerns for their synthesis that produces long-term effects on the ecology. Green nanomaterials are an alternative that are made with environmentally friendly procedures and ingredients that produce less waste. In the field of materials science, “green” synthesis has received a lot of attention as a dependable, long-lasting, and environmentally friendly method for the preparation of a variety of nanomaterials, such as metal/metal oxide nanoparticles, carbon-based nanomaterials, and composite materials. As a result, green synthesis is recognized as a significant tool for reducing the detrimental impacts of standard nanomaterials synthesis methods used in laboratories and industries. Further, the synthesized green nanomaterials are suited for a variety of therapeutic applications due to their outstanding biocompatibility. They show antitumor characteristics, anticancerous properties, and toxicity to numerous disease-causing organisms. In this chapter, the approaches behind the fundamental process, mechanism, and various techniques for synthesizing green nanomaterials are discussed. The current research on the biogenesis of green nanomaterial and the characteristics of green nanomaterials generated with plant extracts, bacteria, fungus, and algae are summarized in this chapter. Finally, the potential uses of the green nanomaterials in electrochemical sensing and therapeutic fields are also discussed. The chapter’s assessment of green nanomaterials uses, their synthesis, and potential applications will be beneficial to scholars in this burgeoning discipline. © Springer Nature Switzerland AG 2023.
Enhanced adsorption of tetracycline from wastewater using MgAl-layered double hydroxides on MWCNTs: influence of humic acid and fluorescence quenching
(Taylor and Francis Ltd., 2025) Ravindra Kumar Gautam; Jyoti Prajapati; Kanchan Gautam; Deeksha Prajapati; I. C. Tiwari
In this paper, the MgAl-layered double hydroxide supported on multiwalled carbon nanotubes (MgAl LDH@MWCNT) nanocomposite was successfully synthesised and characterised for respective analytical methods to elucidate the new structure and composite functional groups. MgAl LDH@MWCNT nanocomposite was applied for the interaction and adsorption of tetracycline from water in the presence of humic acid. The remediation of tetracycline by MgAl LDH@MWCNT nanocomposite for 25, 50 and 100 mg/L concentrations was 94.4%, 90% and 85%, respectively, and 90 minutes of contact time was optimum for adsorption. Remediation of tetracycline was 96.8%, 95.2% and 89% for 25, 50 and 100 mg/L at pH 4. Ultrasonically assisted remediation of tetracycline without the addition of humic acid for 25, 50, and 100 mg/L was 87%, 82% and 76%, respectively, within 5 minutes. Fluorescence quenching indicates that the sorption process is a single-step quenching for humic acid with tetracycline, and quenching intensity was increased with increasing tetracycline concentration. Quenching study revealed that the interaction between the humic acid and tetracycline was static quenching, which means that the non-fluorescent complex was formed. The binding constant Kb was obtained as 6.775 × 103 L mol−1, and the number of binding sites for tetracycline with humic acid was 1.447. 3D fluorescence spectra show a shoulder peak appearance at Ex/Em = 480–575 nm/550–630 nm, which is due to the formation of a stable complex between the interaction of humic acid and tetracycline in the presence of MgAl LDH@MWCNT nanocomposite. Tetracycline adsorption was controlled by electrostatic interaction, which involved electron sharing. Multilayer adsorption on the surface of MgAl LDH@MWCNT was observed, which is due to the sharing of electrons and π-π stacking. © 2025 Informa UK Limited, trading as Taylor & Francis Group.
Fabrication of a novel screen-printed carbon electrode based disposable sensor for sensitive determination of an endocrine disruptor BPSIP in environmental and biological matrices
(Elsevier Inc., 2023) Ankit Kumar Singh; Shreanshi Agrahari; Ravindra Kumar Gautam; Ida Tiwari
A screen-printed electrochemical sensor based on a graphene-modified screen-printed carbon electrode decorated with graphitic carbon nitride (g-C3N4@GN/SPCE) was examined for its ability to act as a sensitive and selective novel sensor for on-site monitoring of an endocrine disruptor, 4-(4-isopropoxy-benzenesulfonyl)-phenol (BPSIP). The successfully prepared g-C3N4 was thoroughly characterized using FESEM, TEM, EDX, FT-IR, XRD, UV– visible studies, and TGA. The prepared g-C3N4 was immobilized on GN/SPCE to prepare a low-cost and disposable sensor for electroanalytical measurement of BPSIP. The concentration of nanomaterial dispersion, pH, and composition of the buffer solution were also optimized for maximal response. At the optimized conditions, BPSIP was determined by cyclic voltammetry in two linear concentration ranges (1–100 µM and 100–1000 µM) with a very low detection limit of 0.02 ± 0.01 µM and unparalleled sensitivity of 0.9162 ± 0.0003 µA.µM−1.cm−2. Further, the electrochemical oxidation of BPSIP occurred at 0.65 V, suggesting the excellent electrocatalytic performance of g-C3N4@GN/SPCE. The proposed sensor has shown high repeatability and reproducibility as well as good anti-interference properties for BPSIP sensing. The feasibility of the as-prepared sensor is also tested in biological and water samples, with excellent recoveries in the range of 98–104 % for BPSIP sensing. © 2023
Fabrication of an innovative electrochemical sensor based on graphene-coated silver nanoparticles decorated over graphitic carbon nitride for efficient determination of estradiol
(Springer, 2024) Ankit Kumar Singh; Shreanshi Agrahari; Ravindra Kumar Gautam; Ida Tiwari
Monitoring small amount of endocrine disrupting chemical, estradiol (E2) residue in environmental and biological samples is extremely important because of its possible connections to breast and prostate malignancies and gastrointestinal disorders. The newly synthesized graphene-coated silver nanoparticles (GN@Ag) decorated on graphitic carbon nitride (g-C3N4)-based hybrid nanomaterial (GN@Ag/g-C3N4) was used to modify glassy carbon electrode (GCE) for electroanalytical measurement of E2. The GN@Ag/g-C3N4 nanocomposite prepared through ultrasonic-assisted reflux methodology was characterized using various physicochemical methods. The scanning electron microscopy and transmission electron microscopy have shown that GN@Ag nanoparticles were decorated and randomly dispersed over g-C3N4 sheets. The exceptional electrochemical response towards the oxidation of E2 was observed through cyclic voltammetry due to the quick electron transfer ability and superior conductivity of GN@Ag/g-C3N4/GCE. The detection limit was found to be 0.002 μM with wide linear range of E2 concentration (0.005–8.0 μM) along with remarkable stability of the fabricated electrode for 21 days showing 91% retention in initial current. The kinetic parameters such as catalytic rate constant and diffusion coefficient for E2 were estimated to be 1.1 × 105 M−1 s−1 and 1.9 × 10−4 cm2 s−1, respectively, by employing chronoamperometry. The proposed sensor also demonstrated its practical applicability for E2 determination in environmental and biological samples with a recovery range of 95–104%. Furthermore, the developed sensing platform is much better compared to reported methods in terms of simplicity, accuracy, detection limit, linearity range, and usefulness in real sample for E2 sensing. Graphical abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2022. Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
Fabrication of gadolinium decorated spherical zinc oxide attached on carbon nanotubes (Gd@ZnO-MWCNTs) for electrochemical detection of a bisphenol derivative BPSIP in real sample matrices
(Springer Science and Business Media B.V., 2023) Shreanshi Agrahari; Ankit Kumar Singh; Ravindra Kumar Gautam; Ida Tiwari
In this study, we have developed a reliable electrochemical sensing platform for determining the residue of 4-(4-iso-propoxy-benzenesulfonyl)-phenol (BPSIP), an endocrine disruptor in blood serum, plastic and paper samples. A wide concentration range of BPSIP was electrochemically determined for the first time on glassy carbon electrode modified with newly developed gadolinium doped zinc oxide-multiwalled carbon nanotubes nanocomposite (Gd@ZnO-MWCNTs/GCE). The Gd@ZnO-MWCNTs nanocomposite was prepared by simple procedure through stirring under reflux condition and was characterized by several physicochemical techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDAX), and X-ray photoelectron spectroscopy (XPS). The electrochemical activity of the prepared nanocomposite was investigated by the differential pulse voltammetry (DPV). It was observed that Gd@ZnO-MWCNTs/GCE exhibits lower oxidation potential toward oxidation of BPSIP due to its fast electron transfer capability and high conductivity. A wide linear concentration ranges from 0.5 to 80 µM was attained with LOD of 0.2 µM. The sensitivities were found to be 26.33 µA mM−1and 14.89 µA mM−1 in two successive concentration ranges. The kinetic studies were also performed by employing chronoamperometry in the presence of BPSIP at Gd@ZnO-MWCNTs/GCE that exhibits catalytic rate constant (kcat) of 7.54 × 102 M−1 s−1 and the diffusion coefficient (D) of 1.56 × 10–5 cm2s−1. Further, the fabricated Gd@ZnO-MWCNTs/GCE has shown excellent reproducibility with resultant RSD of 0.21% and storage stability of 21 days with 86% retention in current. Graphical abstract: [Figure not available: see fulltext.]. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.
Graphene oxide supported Fe3O4-MnO2 nanocomposites for adsorption and photocatalytic degradation of dyestuff: ultrasound effect, surfactants role and real sample analysis
(Taylor and Francis Ltd., 2024) Ankit Kumar Singh; Ravindra Kumar Gautam; Shreanshi Agrahari; Jyoti Prajapati; Ida Tiwari
Present work demonstrates the synthesis, characterisation and application of a novel hybrid nanocomposite GO@Fe3O4-MnO2 for adsorption and catalytic degradation of dyestuff malachite green and tartrazine from wastewater. The nanocomposite GO@Fe3O4-MnO2 was characterised by FT-IR, XRD, SEM-EDS and pHzpc. Effects of various optimising parameters such as contact time, solution pH, surfactants, light, adsorbent dose, ultrasonication and coexisting ions were investigated. The removal efficiencies of malachite green and tartrazine were observed as high as 99.9% and 98% under direct sunlight, respectively. The adsorption kinetics follows the pseudo-second order model (R2 = 0.99) where k2 for malachite green and tartrazine were 0.0097 and 0.0011 g mg−1 min−1, respectively, that means adsorption was controlled by chemisorption. Equilibrium adsorption isotherm of these dyes was analysed in the context of Langmuir and Freundlich models, and the maximum adsorption capacity for Langmuir isotherm was found to be 8.0 and 5.1 mg g−1 for malachite green and tartrazine, respectively. The percentage removal was initially low, but when the ultrasound was irradiated, the removal percentage (96% for malachite green and 98% for tartrazine) was drastically increased because of the formation of highly active •H and •OH radicals in the water through the decomposition of water molecules by the formation of hot spots. On treatment with H2O2, advance oxidation processes were observed with high remediation percentage (99.5% for malachite green and 98% for tartrazine) of dye. The synthesised GO@Fe3O4-MnO2 was finally used for the treatment of dyes from real water samples. The used nanocomposite was separated using an external magnet and recycled with 0.1 N HCl or 0.1 N NaOH as desired. © 2022 Informa UK Limited, trading as Taylor & Francis Group.
Heavy Metals in the Aquatic Ecosystem: Sources, Transport, Toxicity Mechanism, and Mitigation Strategies
(CRC Press, 2025) Ravindra Kumar Gautam; Vriddhi K. Nigam; Dhirendra Kumar Bharati; Shiva Prakash Singh Kushwaha; Subhash Chandra; Radha Rani
Any “metal” or “metalloid” element with a density between 3. 5 to 7 g cm−3 is generally termed a “heavy metal” which is poisonous when present in excess amounts as recommended by various government agencies. Heavy metals are hazardous environmental pollutants and are becoming one of the most serious environmental problems because of their persistence, toxicity, non-biodegradability, and ability to be incorporated into the food chain. Over the past century, heavy metals containing industrial effluents have been discharged into the world's rivers and lakes as a result of rapid industrialization, and, consequently, they have accumulated in aquatic animals, marine species, and sediments. These commonly heavy metals include zinc (Zn), nickel (Ni), copper (Cu), cobalt (Co), chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), iron (Fe), arsenic (As), selenium (Se), and mercury (Hg). These heavy metals when present in excess amounts can cause negative impacts on animals, plants, and human beings which may damage the photosynthesis activities in plants, can damage water uptake, disrupt the function of the xylem and phloem, it may create obstacles in the transportation of prepared foods in the leaves, whereas in animals and human beings, it may damage the function of the brain, liver, kidney, lungs, sometimes even creates alteration in the blood composition. Hence, heavy metals source, fate, transport, and toxicity needs to be explored widely. In this chapter, we are discussing the presence, fate, transport, toxicity, and remediation technologies for heavy metals. This chapter will provide an overview of heavy metals in the aquatic ecosystem. © 2026 selection and editorial matter, Ravindra Kumar Gautam, Subhash Chandra, and Radha Rani; individual chapters, the contributors.
Humic acid functionalized magnetic nanomaterials for remediation of dye wastewater under ultrasonication: Application in real water samples, recycling and reuse of nanosorbents
(Elsevier Ltd, 2020) Ravindra Kumar Gautam; Ida Tiwari
Water pollution by industrial sector is a great problem which hampers the sustainable development goals. Dye containing water effluent poses vast challenge to clean water before its discharge in to the surrounding ecosystem. Herein, we prepared humic acid functionalized Fe3O4 nanosorbents through an eco-friendly route and applied for decolorization of carcinogenic dye from water. The nanosorbents was characterized by AFM, BET surface area analyzer, FTIR, SEM-EDX, TEM, TGA/DTG, VSM and XRD. Adsorption experiments were conducted by taking the appropriate amount of dye in different sources of water under ultrasonication. Adsorption process was controlled by chemisorption in nature making pseudo-second-order model most suitable. Multilayer adsorption was taking place on the active sites of nanosorbents showing applicability of Freundlich isotherm model with highest adsorbed amount of 199.986 mg g−1 at 323 K. Rise in temperature favors the remediation of colored effluent thus positive value of ΔH° (74.234 kJ mol−1) and negative value of ΔG° shows endothermic and spontaneous nature of adsorption system. Cationic surfactant CTAB favors the adsorption (<80%) while anionic SDS gives very low removal (>48%) because of the micelle formation at the surface of nanosorbents. Decolorization from real water samples shows that the adsorption of malachite green was 97, 90, 91, 87, and 86% for Ganga river water, tap water, well water, hand pump water and submersible water, respectively. The used Fe3O4/HA nanosorbents was easily recycled from water samples through 0.1 M HCl and nanosorbents was used up to five cycles with greater percentage of removal at 85%. © 2019 Elsevier Ltd
Millimolar analysis of para benzoquinone in water samples using MnO2 coupled bimetallic MOF-functionalized carbon nanotubes-based nanocomposite
(Elsevier Ltd, 2023) Shreanshi Agrahari; Ankit Kumar Singh; Ravindra Kumar Gautam; Ida Tiwari
A voltammetric sensor based on carbon nanotubes and bimetallic metal organic frameworks coupled with MnO2 based nanocomposite (MnO2@Co-NiMOFs/fMWCNTs) has been prepared for the detection of para-benzoquinone (PBQ). For the first time, a wide concentration range of PBQ was electrochemically evaluated on glassy carbon electrode modified with newly created nanocomposite. The prepared nanocomposites were characterised using FTIR, EDX, XRD, SEM, TEM and HR-TEM. The CV-based sensor demonstrated a linear response in a concentration range of 0.02-26.15 mM, a sensitivity of 2.66 μA mM−1, whereas LOD and LOQ were 88 µM and 294 µM, respectively. Chronoamperometry was used to study the kinetics of PBQ at MnO2@Co-Ni MOFs/fMWCNTs /GCE, where catalytic rate constant (kcat) of 2.72×104 M−1 s−1 and a diffusion coefficient of 3.96×10−4 cm2 s−1 were obtained. The developed sensor has shown percentage recovery of 99.40 –102.2 % for PBQ in different water samples that shows its compatibility in real samples. © 2023
Nano-biosorbents and Their Applications in Electrochemical Sensing and Adsorptive Removal of Environmental Pollutants
(CRC Press, 2024) Shreanshi Agrahari; Ankit Kumar Singh; Ravindra Kumar Gautam; Ida Tiwari
Global pollution has increased due to the continuous release of contaminants into the environment. An eco-friendly method has been used to combat environmental pollution. Many are interested in removing pollutants by biosorption using nano-biosorbents. Nano-biosorbent is essential for the effective and affordable decontamination of polluted materials. Agricultural waste, biomass, biological waste, bacteria, fungi, algae, and metal nanoparticles may all be used in its synthesis. Nano-biosorbents may be analyzed using a variety of spectroscopic and microscopic methods, including UV Visible diffuse reflectance spectra (UV-DRS), Fourier transform infrared spectroscopy (FT-IR), photo luminescence, Brunauer–Emmett–Teller (BET), Field emission Scanning Electron Microscopy (FE-SEM), High-resolution transition electron microscopy (HR-TEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray Powder Diffraction (XRD), and Dynamic light scattering (DLS). Nano-biosorbents are cheaper and more effective than other methods for removing contaminants substances from environmental matrices. Nano-biosorbents are renewable, sustainable, greener, and eco-friendly materials used to remove pollutants. Further, by using these nano-biosorbents in the electrochemical sensing has got many applications such as in clinical diagnostics, environmental monitoring, food freshness, and bioprocess monitoring. This chapter discusses the various electrochemical method, immobilization processes, and strategies for producing nano-biosorbent. Further, various electrochemical techniques used for detecting these nano-biosorbents were also explained. © 2024 selection and editorial matter, Pramod Kumar Mahish, Dakeshwar Kumar Verma, and Shailesh Kumar Jadhav; individual chapters, the contributors.
Nanoscale layered double hydroxide modified hybrid nanomaterials for wastewater treatment: A review
(Elsevier B.V., 2022) Ravindra Kumar Gautam; Ankit Kumar Singh; Ida Tiwari
Wastewater treatment has been a major challenge for scientific society due to complex nature of wastewater and increased demand of clean water supply. In this review, we have critically examined the progress made in development of nanoscale layered double hydroxide (LDH) based hybrid nanomaterials for the treatment of different kind of environmental pollutants present in wastewater. Broad analyses on synthesis of LDH nanomaterials through various routes and their modification by carbon nanotubes, graphene oxides, graphitic carbon nitrides, and magnetic nanomaterials have been given. A survey on characterization tools like XRD, SEM-EDS, TEM, FTIR, XPS, TGA-DTA, and BET surface area are also given. Applications of LDH based hybrid nanomaterials for the cleaning of wastewater containing heavy metals, dyes, antibiotics, phosphates, pharmaceuticals, and other organic compounds have been critically discussed. Role of solution pH, temperature, and co-existing ions as operating parameters were examined and a remediation mechanism towards LDH and pollutants interaction have been drawn. Application of LDH nanomaterials for real wastewater system has been evaluated. An analysis of recycling and regeneration of LDH nanocomposites have been also compiled. Although LDH based hybrid nanomaterials have been used in every spheres of wastewater remediation, yet, there are some major issues like application in multi-pollutant system, remediation of emerging contaminants such as harmful hormones, enhancement of surface area, and inactivation of harmful microorganisms still needs to be solved. Further attention is needed in the low-cost synthesis of LDHs based nanocomposites so it can be easily applied in the real wastewater systems. © 2022 Elsevier B.V.