Synthesis of hierarchically structured T-ZnO-rGO-PEI composite and their catalytic removal of colour and colourless phenolic compounds

Tapered cross-linked ZnO nanowire bundle arrays on three-dimensional graphene foam for highly sensitive electrochemical detection of levodopa

It is crucial to accurately and rapidly monitor the levodopa (LD) concentration for accurate classification and treatment of dyskinesia in Parkinson's disease. In this paper, 3D graphene foam (GF) with a highly conductive network is obtained by chemical vapor deposition. 3D GF serves as the substrate for hydrothermal in situ growth of tapered cross-linked ZnO nanowire bundle arrays (ZnO NWBAs), enabling the development of a highly sensitive detection platform for LD. The formation mechanism of a tapered cross-linked ZnO nanowire bundle arrays on 3D GF is put forward. The integration of 3D GF and ZnO NWBAs can accelerate the electron transfer rate and increase the contact area with biomolecules, resulting in high electrochemical properties. The electrode composed of ZnO NWBAs on 3D GF exhibits significant sensitivity (1.66 µA·µM-1·cm-2) for LD detection in the concentration range 0-60 µM. The electrode is able to rapidly and specifically determine LD in mixed AA or UA solution. The selectivity mechanism of the electrode is also explained by the bandgap model. Furthermore, the successful detection of LD in serum demonstrates the practicality of the electrode and its great potential for clinical application.

Toxicity of bisphenol A and p-nitrophenol on tomato plants: Morpho-physiological, ionomic profile, and antioxidants/defense-related gene expression studies

Bisphenol A (BPA) and p-nitrophenol (PNP) are emerging contaminants of soils due to their wide presence in agricultural and industrial products. Thus, the present study aimed to integrate morpho-physiological, ionic homeostasis, and defense- and antioxidant-related genes in the response of tomato plants to BPA or PNP stress, an area of research that has been scarcely studied. In this work, increasing the levels of BPA and PNP in the soil intensified their drastic effects on the biomass and photosynthetic pigments of tomato plants. Moreover, BPA and PNP induced osmotic stress on tomato plants by reducing soluble sugars and soluble proteins relative to control. The soil contamination with BPA and PNP treatments caused a decline in the levels of macro- and micro-elements in the foliar tissues of tomatoes while simultaneously increasing the contents of non-essential micronutrients. The Fourier transform infrared analysis of the active components in tomato leaves revealed that BPA influenced the presence of certain functional groups, resulting in the absence of some functional groups, while on PNP treatment, there was a shift observed in certain functional groups compared to the control. At the molecular level, BPA and PNP induced an increase in the gene expression of polyphenol oxidase and peroxidase, with the exception of POD gene expression under BPA stress. The expression of the thaumatin-like protein gene increased at the highest level of PNP and a moderate level of BPA without any significant effect of both pollutants on the expression of the tubulin (TUB) gene. The comprehensive analysis of biochemical responses in tomato plants subjected to BPA and PNP stress illustrates valuable insights into the mechanisms underlying tolerance to these pollutants.

A Zn-based metal coordination cluster Zn5 used for solid phase microextraction of ten phenolic compounds from water and soil

Exploring coating materials with superior extraction efficiency has always been the pursuit in the field of solid phase microextraction (SPME). Metal coordination clusters with high thermal and chemical stability, abundant functional groups as active adsorption site are the promising coatings. In the study, a Zn₅(H₂Lⁿ)₆(NO₃)₄ (Zn₅, H₃Lⁿ =(1,2-bis-(benzo[d]imidazol-2-yl)-ethenol) cluster coating was prepared and applied for SPME of ten phenols. Zn₅ based SPME fiber exhibited high extraction efficiencies for phenols in headspace (HS) mode, which circumvented the pollution of SPME fiber. The adsorption isotherm and theoretical calculation indicated the adsorption mechanism of phenols on Zn₅ was hydrophobic interaction, H-bond interaction and π-π stacking. Under the optimized extraction conditions, an HS-SPME-GC-MS/MS method was developed for the determination of ten phenols in water and soil samples. For ten phenolic compounds in water and soil samples, the linear ranges were 0.5-5000 ng/L and 0.5-250 ng/g, respectively. The limits of detection (LODs, S/N = 3) were 0.010-1.20 ng/L and 0.0048-0.16 ng/g, respectively. The precisions of single fiber and fiber-to-fiber were lower than 9.0% and 14.1%, respectively. The proposed method was applied for the detection of ten phenolic compounds in various water and soil samples, showing satisfactory recovery (72.1-118.8%). This study delivered a novel and efficient SPME coating material for the extraction of phenols.

Analysis of impacts of exogenous pollutant bisphenol-A penetration on soybeans roots and their biological growth

Bisphenol A (BPA) is a common chemical used in plastic production. BPA, which has the potential to be poisonous to plants, has lately emerged as a serious environmental concern owing to its extensive usage and release patterns. Prior study has only looked at how BPA affects plants up to a certain stage in their growth. The precise mechanism of toxicity, penetration of BPA, and damage to internal root tissues remains unknown. Therefore, the goal of this study was to examine the hypothesized mechanism for BPA-induced root cells by studying the effects of bisphenol A (BPA) on the ultrastructure and function of root tip cells of soybean plants. We looked at plant changes in root cell tissues after BPA exposure. Further, the biological characteristics that responded to BPA stress were investigated, and the accumulation of BPA in the root, stem, and leaf of the soybean plant was systematically investigated by using FTIR and SEM analysis. The uptake of BPA is a key internal factor that contributes to changes in biological characteristics. Our findings provide insight into how BPA could alter plant root growth, which might contribute new knowledge toward a better scientific appraisal of the possible dangers of BPA exposure for plants.

Synthesis of Transparent ZnO–TiO2 and Its Nanocomposites for Ultraviolet Protection of a Polyethylene Terephthalate (PET) Film

The goal of this research was to investigate the effects of ZnO–TiO2 and its nanocomposites, on the physical, mechanical, and ultraviolet protection of polyethylene terephthalate (PET). Exposure to ultraviolet (UV) rays is a major cause of the degradation of the quality and optical properties of materials in addition to skin cancer; therefore, research on UV-blocking materials that are safe and have fewer side effects than currently available products is being actively conducted. In this study, a material with UV-blocking capability was synthesized while ensuring the transparency of ZnO and TiO2. ZnO–TiO2 and its various composites were successfully synthesized via a hydrothermal method followed by ball milling and their properties were systematically analyzed by using scanning electron microscopy, X-ray diffractometry, Fourier-transform infrared spectroscopy, and water contact angle measurements. Furthermore, a simple dip-coating method was employed to prepare transparent polyethylene terephthalate (PET) films coated with the composites, which were subsequently investigated for UV-blocking properties by exposing them to UV irradiation. The hydroxyl groups of ZnO and TiO2, as representative inorganic sunblock components, were removed by using 3-chloropropyl trimethoxy silane as a coupling agent to improve their wettability in an organic solvent as well as their dispersibility and stability. The addition of a small amount of Tinuvin® allowed the hybrid organic and inorganic components to exhibit transparent UV-blocking characteristics, with a UV transmittance of ≤20% and 90% visible transmittance. These results, thus, serve as a basis for contributing to applications in the field of packaging, health, and hygiene industries.

Fabrication of Polyethyleneimine-Functionalized Magnetic Cellulose Nanocrystals for the Adsorption of Diclofenac Sodium from Aqueous Solutions

Diclofenac sodium (DS), one of the most used non-steroidal anti-inflammatory drugs worldwide, is often detected in wastewater and natural water. This drug is ecotoxic, even at low concentrations. Therefore, it is essential to fabricate low-cost adsorbents that can easily and effectively remove DS from contaminated water bodies. In this study, a polyethyleneimine (PEI)-modified magnetic cellulose nanocrystal (MCNC) was prepared with a silane coupling agent as a bridge. TEM, FTIR, XRD, and VSM were used to demonstrate the successful preparation of MCNC-PEI. This composite adsorbent exhibited efficient DS removal. Furthermore, the adsorption performance of MCNC-PEI on DS was optimal under mildly acidic conditions (pH = 4.5). Adsorption kinetics showed that the adsorption process involves mainly electrostatic interactions. Moreover, the maximum adsorption capacity reached 299.93 mg/g at 25 °C, and the adsorption capacity only decreased by 9.9% after being reused five times. Considering its low cost, low toxicity, and high DS removal capacity, MCNC-PEI could be a promising adsorbent for treating DS-contaminated water.

Hydrothermal synthesis of copper (׀׀) oxide-nanoparticles with highly enhanced BTEX gas sensing performance using chemiresistive sensor

In the present work, the cost effective and facile hydrothermal synthesis technique was adopted to synthesize the copper (׀׀) oxide (CuO)-Nanoparticles (NPs). Physico-chemical characterization of the synthesized CuO-NPs was done by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM) analysis were carried out to study the structural, optical, and surface morphology of nanomaterial. XRD analysis revealed that the synthesized CuO-NPs had monoclinic structure and the average crystallite size is 20 nm. FTIR spectra indicate the vibrational bands of metal oxygen bonds (Cu-O). UV-visible absorption spectra were utilized to determine the energy band gap (E_g) of the CuO-NPs. In addition, we fabricated the chemiresistive sensor using synthesized CuO-NPs for detecting Volatile Organic Compounds (VOCs). These results demonstrate that CuO-NPs based chemiresistive sensor is ideal for qualitative detection of BTEX chemicals vapors (i.e. Benzene, Toluene, Ethylbenzene, and Xylene).

MoS2 Decoration Followed by P Inclusion over Ni-Co Bimetallic Metal-Organic Framework-Derived Heterostructures for Water Splitting

Demonstrating a highly efficient non-noble bifunctional catalyst for complete water electrolysis remains challenging because of kinetic limitations and crucial importance for future energy harvesting. Herein, a low-cost, integrated composite of a Ni-Co metal-organic framework decorated with thin MoS₂ nanosheets was synthesized by a simple hydrothermal method followed by carbonization and phosphorization for electrochemical oxygen and hydrogen evolution reactions. Such a composite heterostructure exhibits outstanding performance in the electrocatalysis process with a lower overpotential of 184 mV for the oxygen evolution reaction (OER) and 84 mV for the hydrogen evolution reaction (HER) in 1.0 M KOH and 0.5 M H₂SO₄ electrolytes to reach a current density of 10 mA cm^-2, with a slight Tafel slope of 63 mV dec^-1 for the OER and 96 mV dec^-1 for the HER. The obtained results are far better than those of the commercial benchmark catalyst. Furthermore, online gas chromatography quantifies the amount of hydrogen generation in a symmetric cell as equal to 0.002121 moles with an energy efficiency of about 2.237 mg/kWh. Thus, the composite electrode's remarkable performance is further demonstrated as a potentially viable alternative non-noble electrocatalyst for energy conversion reactions.

Oxidizing agent impacting on growth of ZnO tetrapod nanostructures and its characterization

In this paper, the fabrication of ZnO tetrapod was investigated. It was synthesized by the thermal oxidation technique using metal zinc powder mixed with oxidizing agents such as hydrogen peroxide (H₂O₂) and ammonium persulfate ((NH₄)₂S₂O₈). The furnace heating temperature reached at 1000 °C in the air. The average diameter and length of a tetrapod leg for mixture with H₂O₂ from SEM were 45.3 nm and 1.57 μm, respectively. The oxygen vacancy (36%) of ZnO tetrapod with H₂O₂ was higher than 33% of ZnO tetrapod with only Zn. Growth mechanism of ZnO tetrapod was processed via the formation of Zn nucleus and growing the wurtzite structure. The growing directions of ZnO crystal conformed with the [0001] direction. ZnO tetrapod showed up the high resolution TEM image with the lattice spacing 0.252 nm. From these results, this work was indicated that H₂O₂ solution was a better oxidizing reaction helper to make ZnO tetrapod nanostructures than anything else.

Monitoring the decolourisation efficacy of advanced membrane fabricated phytosilica nanoparticles in textile effluent water treatment

Silica nanoparticles are generally mesoporous that are predominant in the sand and rocks. Silica nanoparticles have a wide range of applications in various fields such as medicine, waste management, effluent treatment and electronics. The present work has explored the synthesis of silica nanoparticles through acid and alkaline leaching method from Pedalium murex which is a common weed that is found in southern parts of Tamil Nadu. Silica nanoparticles (SiNps) and its functional groups were confirmed by EDX and FTIR analysis with their respective energy dispersion levels and wavenumbers. Size, shape and morphological features of SiNps were analysed by PSA, TEM and SAED analysis. Synthesised and characterized nanosilica was crosslinked over nylon-66 and cellulose nitrate membranes and were confirmed by FTIR analysis for their crosslinking with SiNps. Water retention activity of the crosslinked and non crosslinked membranes was analysed by contact angle measurement to ensure the receptability of the membranes to remove contaminants by the adsorption. The decolourisation efficiency of the crosslinked nylon 66 membrane was found as a potential source for the treatment with 65.5% colour reduction when compared with other membranes. A slight reduction of solid profiles and COD ranges were achieved for crosslinked membranes than non crosslinked membranes.