Search

A novel series of benzimidazole-based molecules mimicking biological receptors, which exhibit selective coordination with zinc ions, were designed and synthesized. The photochromic behavior of these derivatives with various metal ions suggests a selective interaction of one of the receptors 2-(pyridin-2-yl)-4,7-di(thiophen-2-yl)-3

Polyethylene terephthalate is a common plastic in many products such as viscose rayon for clothing, and packaging material in the food and beverage industries. Polyethylene terephthalate has beneficial properties such as light weight, high tensile strength, transparency and gas barrier. Nonetheless, there is actually increasing concern about plastic pollution and toxicity. Here we review the properties, occurrence, toxicity, remediation and analysis of polyethylene terephthalate as macroplastic, mesoplastic, microplastic and nanoplastic. Polyethylene terephthalate occurs in groundwater, drinking water, soils and sediments. Plastic uptake by humans induces diseases such as reducing migration and proliferation of human mesenchymal stem cells of bone marrow and endothelial progenitor cells. Polyethylene terephthalate can be degraded by physical, chemical and biological methods.

Functionalized carbon dots (CDs) derived from Citrobacter freundii bacterial cells were used for selective detection of Cr(VI). A microwave-heating-based green synthesis approach is adopted to produce functionalized CDs from C. freundii bacterial cells (CF-CDs). The reaction was carried out in a 500 W microwave digester at 200°C for 20 min. The supernatant was filtered with a 0.2 µm filter and highly monodisperse CDs were obtained. Inherent functionalization of CF-CDs with nitrogen and oxygen-containing functional groups made them extremely selective toward Cr(VI) with a lower limit of detection of ~1.7 ppm. More importantly, CF-CDs could distinguish between Cr(VI) and Cr(III), which is highly desirable for practical applications. The fabricated sensor had a dual linear response range between 0 and 50 µM and 50-250 µM. The synthesized CDs were inherently functionalized which made them highly selective for Cr(VI) detection. CF-CDs also possess high stability over long storage period. This study reports the facile synthesis and characterization of a highly selective sensor for Cr(VI). As opposed to similar CDs sensors reported for Cr(VI), based on inner-filter effect, CF-CDs exhibit a strong, specific interaction toward Cr(VI), indicated by the large binding constant.

Phorate is a systemic insecticide used to eradicate mites, insects, and nematodes. Extensive use of this organophosphate has engendered severe environmental concerns. The current research aimed to explore the kinetic pathways of phorate biodegradation in aqueous solutions. Two novel bacterial strains Pseudomonas aeruginosa strain PR1 (KP268772.1) and Pseudomonas sp. PR_02 (KP268773.1) were isolated, screened, and developed given their potential to degrade phorate. Mineralization of phorate was assayed with and without the addition of metal ions [Fe (II) and Cu (II)] and humic acid (HA). In 14 days, experiment both strains have consumed about 69%-94.5% (half-life from 3.58 to 6.02 days) of phorate. The observed biodegradation rate of phorate with Cu (II) in the system was 73% and 87%, with a half-life of 4.86 and 4.07 days for PR1 and PR2, respectively. The biodegradation of phorate using Fe(II) was 69% and 82%, with half-life periods 5.68 and 4.49 days. Meanwhile, incorporating HA, the phorate biodegradation was inhibited significantly, showing 71% and 85% degradation, with half-life periods of 6.02 and 5.02 days. The results indicated that both bacterial strains were able to mineralize phorate with PR2 > PR1. Summarizing, the inhibition in phorate biodegradation order under different conditions was as HA > Fe (II) > Cu (II). UV-visible measurements and gas chromatography-mass spectrometric assays indicated that the possible degradation pathway of phorate included ethoxy-phosphonothio-methanethiol S-mercaptomethyl-O,O-dihydrogen phosphorodithioate, diethyl-methylphosphonate, methane dithiol, ethanethiol, and phosphate, as the main metabolites identified. Therefore, it was concluded that the newly isolated Pseudomonas strains could be a potential candidates for biodegradation of phorate in a cost-effective, safe, and environmentally friendly alternative.

In this work, the electromagnetic interference (EMI) shielding properties of an MXene interlayered crosslinked conducting poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) polymer film are investigated. The introduction of a crosslinker into PEDOT:PSS makes PEDOT:PSS water insoluble. An average EMI shielding effectiveness (SE) of ∼41 dB (corresponding to 99.999% blockage) was obtained for a solution coated 6 ± 0.2 μm thick optimized crosslinked PEDOT:PSS-Ti3C2Tx MXene (XPM50) nanocomposite film. Electrodynamic modelling and simulation also suggest an excellent SE for this nanocomposite system. From an application point of view, the specific EMI SE (SSE)/thickness (t) or absolute EMI SE is the most useful factor. The absolute EMI SE of the XPM50 film is observed to be 89 924 dB cm2 g−1, which is nearly nine times higher than that of the pristine PEDOT:PSS film and more than three times higher than that of the Ti3C2Tx MXene film. Mechanistically, the superior EMI shielding due to absorption (SEA) is intrinsically predominant. The crosslinked PEDOT:PSS interconnects with the Ti3C2Tx MXene flakes, generating more absorption sites and enhanced electrical conductivity which is responsible for the high SEA value. The XPM50 film also fulfils many commercial requirements, especially solution processability and outstanding absolute EMI SE, which makes it an attractive EMI shield for real time applications such as telecommunications, health care systems, detective systems, defence, and aerospace applications.

A novel green nanocomposite has been prepared by immobilizing CaO nanoparticles (CaO NPs) on the surface of graphene oxide. Biogenic CaO-NPs were synthesized from Lala clamshells. Morphological and structural characterizations of the nanocomposite were studied extensively. The adsorption capacity (q

Nitrate pollution is eminent in almost all the developing nations as a result of increased natural activities apart from anthropogenic pollution. The release of nitrates in more than critical quantities into the water bodies causes accretion impacts on living creatures, environmental receptors, and human vigour by accumulation through the food chain. Nitrates have recently acquired researchers' huge attention and extend their roots in environmental contamination of surface and groundwater systems. The presence of nitrate in high concentrations in surface and groundwater triggers several health problems, for instance, methemoglobinemia, diabetes, eruption of infectious disorders, harmfully influence aquatic organisms. Sensing nitrate is an alternate option for monitoring the distribution of nitrate in different water bodies. Here we review electrochemical, spectroscopic, and electrical modes of nitrate sensing. It is concluded that, among the various sensors discussed in this review, FET sensors are the most desirable choice. Their sensitivity, ease of use and scope for miniaturisation are exceptional. Advanced functional materials need to be designed to satiate the growing need for environmental monitoring. Different sources of nitrate contamination in ground and surface water can be estimated using different techniques such as nitrate isotopic composition, co contaminants, water tracers, and other specialized techniques. This review intends to explore the research work on remediation of nitrate from wastewater and soil using different processes such as reverse osmosis, chemical denitrification, biological denitrification, ion exchange, electrodialysis, and adsorption. Denitrification proves as a promising alternative over previously reported techniques in terms of their nitrate removal because of its high cost-effectiveness.

Metal-based adsorbents are limited for hexavalent chromium [Cr(VI)] adsorption from aqueous solutions because of their low adsorption capacities and slow adsorption kinetics. In the present study, decorated zinc oxide (ZnO) nanoparticles (NPs) on graphene oxide (GO) nanoparticles were synthesized via the solvothermal process. The deposition of ZnO NPs on graphene oxide for the nanohybrid (ZnO-GO) improves Cr(VI) mobility in the nanocomposite or nanohybrid, thereby improving the Cr(VI) adsorption kinetics and removal capacity. Surface deposition of ZnO on graphene oxide was characterized through Fourie Transform Infra-red (FTIR), UV–Visible, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), and Brunauer–Emmett–Teller (BET) techniques. These characterizations suggest the formation of ZnO-GO nanocomposite with a specific area of 32.95 m2/g and pore volume of 0.058 cm2/g. Batch adsorption analysis was carried to evaluate the influence of operational parameters, equilibrium isotherm, adsorption kinetics and thermodynamics. The removal efficiency of Cr(VI) increases with increasing time and adsorbent dosage. FTIR, FESEM and BET analysis before and after the adsorption studies suggest the obvious changes in the surface functionalization and morphology of the ZnO-GO nanocomposites. The removal efficiency increases from high-acidic to neutral pH and continues to decrease under alkaline conditions as well. Mathematical modeling validates that the adsorption follows Langmuir isotherm and fits well with the pseudo 2nd order kinetics (Type 5) model, indicating a homogeneous adsorption process. The thermodynamics study reveals that Cr(VI) adsorption on ZnO-GO is spontaneous, endothermic, and entropy-driven. A negative value of Gibb's Free Energy represents the thermodynamic spontaneity and feasibility of the sorption process. To the best of our knowledge, this is the first study of Cr(VI) removal from aqueous solution using this hybrid nanocomposite at near-neutral pH. The synthesized nanocomposites prove to be excellent candidates for Cr(VI) removal from water bodies and natural wastewater systems.

Polyvinyl alcohol (PVA) is a great interest polymer due to its excellent film-forming, emulsifying, microwave dielectrics and adhesive properties. However, PVA is a water-soluble synthetic polymer making it susceptible to environmental factors. In this work, PVA is crosslinked at room temperature using divinyl sulfone (DVS) as a crosslinker, and the obtained crosslinked PVA (XPVA) is water-insoluble. Crosslinking mechanism is proposed, thermal and microwave dielectric properties of X-PVA are studied. The studies revealed that X-PVA has better thermal stability and microwave absorption properties. The obtained minimum reflection loss (RL) of X-PVA is -23 dB (filler-free) with entire X-band (8.2-12.4 GHz) absorption bandwidth (RL ≤ -10 dB), indicating excellent microwave absorption properties. Artificial neural network (ANN) predicted RL of X-PVA also matched well with the experimental data. Electromagnetic power simulation suggests that the microwave power absorption density due to the dielectric loss is intrinsically predominant in X-PVA compared to the pristine PVA. Further, the ratio of electromagnetic energy to heat energy conversion power (absorption) of X-PVA is much higher than pristine PVA, indicating the suitability for self-powered devices. X-PVA also fulfils many commercial requirements such as bulk level facile synthesis, large area fabrications, ultralight, and inexpensive. P.C.R. would like to acknowledge the Government of India, Ministry of Defence Aeronautics Research & Development Board (ARDB/01/2031900/M/I) for financial support of this work.

Antibiotics overuse, inappropriate conduct, and discharge have led to adverse effects on various ecosystems. The occurrence of antibiotics in surface and drinking water is a matter of global concern. It is responsible for multiple disorders, including disruption of endocrine hormones and high chronic toxicity. The hospitals, pharmaceutical industries, households, cattle farms, and aquaculture are the primary discharging sources of antibiotics into the environment. This review provides complete detail on applying different nanomaterials or nanoparticles for the efficient removal of antibiotics from the diverse ecosystem with a broader perspective. Efforts have been made to focus on the degradation pathways and mechanism of antibiotic degradation using nanomaterials. More light has been shed on applying nanostructures in photocatalysis, which would be an economical and efficient solution. The nanoscale material or nanoparticles have incredible potential for mineralizing pharmaceutical compounds in aqueous solutions at low cost, easy handling characteristics, and high efficacy. Furthermore, nanoparticles can absorb the pharmaceutical by-products and wastes at a minimum cost as they can be easily recycled. With the increasing number of research in this direction, the valorization of pharmaceutical wastes and by-products will continue to expand as we progress from old conventional approaches towards nanotechnology. The utilization of nanomaterials in pharmaceutical wastewater remediation is discussed with a major focus on valorization, energy generation, and minimization and its role in the circular economy creating sustainable development.

With millions of tonnes of plastic pollution generated every year, small-sized plastic particles, including micro- and nanoplastics, end up in freshwater systems. Due to the very small size and very large specific surface area of nanoplastics, they are known to be persistent and toxic in our environment. These particles are also known to react with other water-borne contaminants and cause acute toxicity in organisms. Nanoplastics are prone to biomagnification and can be transported to humans through various pathways. This study aims to contribute towards understanding the behaviour of nanoplastics in our environment, specifically through identification of various sources, detection techniques, toxicity estimation, health risk in humans, environmental fate, recovery and reuse, and future challenges and limitations. Detailed review on the toxic effects of nanoplastics on various organisms and their degradation rates in soil and water matrices are provided. The suitability of small- and large-scale separation techniques for the removal of nanoplastics in wastewater treatment plants is also discussed. Current challenges and future perspectives in understanding the fate and transport of nanoplastics in the environment are also discussed. Research gaps, including the development of quantification techniques, estimation of degradation mechanisms, transport in marine ecosystems, and development of sensors to examine nanoplastics in the environment, are explored. Finally, we can limit the release of nanoplastics to the environment through reduction, reuse and recycling (3 Rs) of bulk plastic products.

Herein, for the adsorption and detection of As (III), multifunctional nanohybrids have been synthesized using a solvothermal approach. Structural and functional characterizations confirmed the impregnation of the ZnO over graphene oxide. Nanohybrid exhibits a remarkable qmax (maximum adsorption capacity) of 8.17 mg/g, at an adsorbent dose of 3 g/L and pH of 8.23. Higher adsorption with nanohybrid was attributed to a large BET surface area of 32.950 m2/g. The chemical nature and adsorption behaviour of As(III) on ZnO-GO were studied by fitting the data with various adsorption isotherms (Langmuir & Freundlich) and kinetics models (six models). It is observed from the findings that removal of As(III) with ZnO-GO nanocomposite appears to be technically feasible with high removal efficiency. The feasibility of the nanocomposite to function as a sensor for the detection of As(III) was also evaluated. The fabricated sensor could detect As(III) with a lower limit of detection of 0.24 μM and linear range up to 80 μM. Overall, this study is significant in nanohybrid as a multifunctional composite for the adsorption and detection of As (III) from wastewater.

Herein, the fabrication of a novel electrochemical sensor based on the 2,6-bis (2-benzimidazoyl) pyridine (BZPY) was carried out using a modified carbon paste electrode (MCPE). BZPY was characterized by FTIR, powder XRD, TGA, and SEM analysis. The developed BZPY/MCPE sensor was effectively employed for the detection of Bisphenol A (BPA) using electrochemical techniques like cyclic voltammetry (CV), differential pulse voltammetry, and electrochemical impedance spectroscopy (EIS). From the electrochemical investigation, BZPY exhibited excellent catalytic behavior for the detection of BPA. The electrode process of the BZPY/MCPE was observed to be diffusion-controlled and a lower detection limit (LOD) was estimated to be 0.029 μM in the linear range of 2–18 μM. Furthermore, stability, selectivity, and reproducibility of the BZPY/MCPE were evaluated. Moreover, the practical applicability of the sensor was examined using water samples with acceptable recovery (94.7–101.2%). In addition, the interaction of BZPY with BPA was evaluated using Molecular Dynamics simulations. These results suggest that BZPY/MCPE system could be used for the detection of BPA.

Pyrethroid pesticides are synthetic products derived from natural pyrethrins isolated from the flowers. It has extensive applications in horticulture, agriculture, and pest control. Pyrethroids are a highly toxic and expeditious insecticide exhibiting tremor-type syndrome, allergic reactions, and ataxia. Regular use of synthetic pyrethroids affects a helpful microbial community and reduces soil fertility. Due to environmental concerns linked with the accumulation of pyrethroids pesticides in groundwater and food products, there is an urgent need to develop rapid, economical and reliable methods amenable to on-site applications. Here, we review recently developed analytical techniques used for estimating pyrethroids and their metabolites, focusing on their removal from environmental specimens, mechanisms, and kinetics. Biodegradation offers an efficient option to mineralize pyrethroid pesticides either into less toxic compounds or useful by-products. Herein we investigate more on their biodegradability by native microbial species by exploring the genes involved in the degradation of pyrethroid pesticides and assessing the mathematical modeling for pyrethroid degradation. We discuss toxicological effects, environmental issues, analytical techniques for estimation, and approaches for efficient biodegradation, which will offer an alternative and affordable option to get noxious pesticides.

Conjugated polymer based sensor materials are gaining attention because of their higher sensitivity, tunable selectivity, better lifetime and reusability. Higher thermal stability and resistance to photobleaching makes them potential candidates for fabrication of thin films, micro-chips and electrodes for sensors. A novel hexylthiophene based polymer has been synthesized for the sensitive detection of Fe3+ ions. The polymer solution in ethanol could detect the presence of 8 ppm of Fe3+ with a quenching efficiency of $\sim 96$%. The Stern-Volmer plot showed positive deviation from linearity at higher analyte concentrations due to super amplified quenching. The prospect of the polymer to function as a chemoresistive sensor is currently being investigated.

A nickel based organometallic complex is reported herein for non-enzymatic detection of urea. Nickel complex of benzimidazoyl pyridine ([Ni(bzimpy)2]Cl2) derivative offers an excellent nickel core for urea sensing. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) have been utilized for analysing the sensing behaviour of urea. The modified carbon paste electrode (MCPE) has a lower limit of detection (LOD) of 1.5 µM with a linear sensing range from 0.01 to 0.1 mm the sensor also exhibits prominent response towards urea, compared to other interferents. The substantial stability and reproducibility of the sensor is augmented by its high recovery rate in real world samples. The utility of the complex as a chemiresistor sensor has also been investigated.

A series of porous organic polymers (POPs) were fabricated based on a boron dipyrromethene (BODIPY) core. The variation of the substituents in the BODIPY core and the fine-tuning of the Sonogashira polycondenzation reaction with 1,3,5-triethynylbenzene led to the formation of POPs with a wide range of surface area and porosity. A 10-fold increase in surface area from 73 m2 g–1 in BDT1a polymer to 1010 m2 g–1 in BDT3 was obtained. Simultaneously, the porosity was changed from mesoporous to ultramicroporous. The surface area of BDT3 turned out to be the highest reported so far for BODIPY-based POPs. Molecular dynamics simulation coupled with Grand Canonical Monte Carlo simulations revealed the effect of substituents alkyl groups and rigidity of the core structures on the surface properties of the POPs. Detailed gas adsorption studies of the polymers revealed a high uptake of CO2 and H2. The highest uptake capacity of 16.5 wt % for CO2 at 273 K and 2.2 wt % for H2 at 77 K was observed for BDT3 at 1 bar press...

Conjugated porous organic polymers based on a novel core of tetraphenyl-5,5-dioctylcyclopentadiene (TPDC) have been fabricated in the form of powder (P1), soluble in common organic solvents (P2) as well as aqueous dispersion of nanoparticles (P3). Fine tuning of the conditions of polycondensation reactions involving tetrakis(4-bromophenyl)-5,5-dioctylcyclopentadiene and diethynylbenzene leads to the formation of TPDC based polymers in three different forms. P1, P2 and P3 possess high thermal stability (up to 375 °C) and are porous in nature. The Brunauer–Emmett–Teller (BET) surface area and total pore volume of P1 were estimated to be 405 m2 g−1 and 0.68 cm3 g−1 respectively. Solid P1 was explored for hydrogen and carbon dioxide adsorption. Solution of P2 and aqueous dispersion of P3 exhibit strong cyan fluorescence and are applied for the sensing of nitroaromatics. Steady state and time resolved fluorescence measurements reveal the underlying photophysics of amplified fluorescence quenching of P2 and P3 by nitroaromatics. Porosity, gas adsorption, as well as solubility, strong fluorescence and sensing capabilities establish TPDC based porous polymers as new multifunctional materials and can find broad applications in sensing and optical devices.

A series of porous organic polymers (POPs) were fabricated based on a boron dipyrromethene (BODIPY) core. The variation of the substituents in the BODIPY core and the fine-tuning of the Sonogashira polycondenzation reaction with 1,3,5-triethynylbenzene led to the formation of POPs with a wide range of surface area and porosity. A 10-fold increase in surface area from 73 m

Conducting polymer ultrathin films with high absolute electromagnetic interference (EMI) shielding effectiveness (SE) is highly desirable for their facile processability. The conducting polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), possesses excellent conductivity. However, a thin film of PEDOT:PSS is water soluble, making it disadvantageous for EMI shielding. Here, a cross-linked, water-insoluble, ultrathin film of PEDOT:PSS for EMI shielding is evaluated. A 9 +/- 1 mu m thick cross-linked PEDOT:PSS film exhibits an average EMI SE of 40 dB. Standard electrodynamics simulation also confirms the experimental data. The most realistic parameter of EMI shielding for practical application is the absolute SE. The absolute SE of cross-linked PEDOT:PSS film is obtained to be 51 480 dB cm(2) g(-1), highest ever reported. Mechanistically, the absorption predominant SE originates from the cross-linking of PEDOT:PSS, resulting in a higher conductivity (769 S cm(-1)) and creating internal reflecting surfaces. The mechanical strength, solution processability, and outstanding absolute EMI SE make cross-linked PEDOT:PSS film to be an attractive EMI shield for real-time applications such as in defense arena.