Analysis of emerging contaminants: A case study of the underground and drinking water samples in Chandigarh, India

The present report deals with the analysis of emerging contaminants and the quality of drinking and underground water supply in Chandigarh, India. A water sampling monitoring and analysis was conducted by collecting a total of 54 samples of underground & drinking water of Chandigarh to analyse the health risk associated with the spread of emerging contaminants in the water sources. The quality of water samples was also assessed by measuring the colour, odour, temperature, pH, electrical conductivity (EC), biological oxygen demand (BOD), dissolved oxygen (DO), total dissolved solids/ salts (TDS) and hardness. For the estimation of the emerging contaminants (Endosulphan (ES) and Hexachlorohexane (HCH)) in the water samples, an extraction procedure was carried out by dispersive liquid-liquid extraction method followed by analysis using gas chromatography-mass spectrometry (GC-MS). The levels of ES and HCH obtained were compared with the drinking water standards of the Bureau of Indian Standards (IS: 10500). The levels of HCH and ES in all the water samples tested were found to be below the detection limit. It cannot be denied that the industrial discharge and other agencies seems to be complying with the regulations. The Initiatives by the Central and State Govt of India seems to have created sensitivity and awareness among the public specifically among the farmers. The limit of detection (LOD) were 1.0 × 10−3 and 2.4 × 10−3 ppm for ES and, HCH respectively. However, some water pollution indicators such as TDS, EC, DO and total hardness were found to exceed the limits specified by the Bureau of Indian Standards (BIS)

Preparation and Characterization of Celecoxib Entrapped Guar Gum Nanoparticles Targeted for Oral Drug Delivery against Colon Cancer: An In-Vitro Study

The present study is an attempt to synthesize nanosized guar gum carriers encapsulating celecoxib as the chemopreventive agent for experimental colorectal cancer (CRC).  Guar gum nanoparticles without celecoxib (eGGNPs) and celecoxib loaded guar gum nanoparticles (cGGNPs) were prepared by oil-in-water emulsification and in situ polymer crosslinking method. Electron microscopy, zeta potential and fourier transform infrared spectra analysis was used to affirm the size, stability and morphology of the nanoparticles. In-vitro drug release was investigated using dialysis method. Further, the effect of nanoparticles (eGGNPs & cGGNPs) was evaluated on Caco 2 colon cancer cell lines. Spherical guar gum nanoparticles were obtained in the size range of 200±6nm with zeta potential of -32.1mV indicating good stability of the GGNPs with drug loading of 30±3.2%, and drug release following zero order kinetics. The eGGNPs had no effect on Caco2 cell viability whereas the cGGNPs showed time and concentration dependent growth inhibition of Caco 2 cells. These findings suggest the successful preparation of chemopreventive nanoparticles that can be targeted as the prophylactic agent for experimental colorectal cancer. Keywords: nanoparticles, guar gum, celecoxib, colorectal cancer, release kinetics, cytotoxicit

Microemulsions as Nanotemplates: A Soft and Versatile Approach

Template efficacy of microemulsions in generating nanoparticles has garnered considerable attention in the world of colloidal science. A microemulsion is an optically isotropic and thermodynamically stable colloidal dispersion, which possess spherical droplets (either of W/O or O/W) of the size <50 nm. In microemulsions, the spontaneous formation of domains of nanometric dimensions significantly facilitates their exploitation as potential nanoreactors for the production of stable nanoparticles (due to their cost-effectiveness and ease of preparation). The present chapter provides an overview of microemulsions as efficient nanotemplates, with a detailed account of plausible nanomaterials, i.e., metallic nanoparticles, quantum dots, polymeric nanoparticles, mesoporous silica nanoparticles, solid lipid nanoparticles, nanostructured lipid carriers, etc. Based on the high surface area, good crystallinity, controllable particle size, outstanding catalytic, and magnetic properties, the exploitation of nanoparticles as efficient catalysts and drug delivery modules has also been highlighted

Bi2WO6/C-dots/TiO2: A novel z-scheme photocatalyst for the degradation of fluoroquinolone levofloxacin from aqueous medium

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Photocatalytic materials and semiconductors of appropriate structural and morphological architectures as well as energy band gaps are materials needed for mitigating current environmental problems, as these materials have the ability to exploit the full spectrum of solar light in several applications. Thus, constructing a Z-scheme heterojunction is an ideal approach to overcoming the limitations of a single component or traditional heterogeneous catalysts for the competent removal of organic chemicals present in wastewater, to mention just one of the areas of application. A Z-scheme catalyst possesses many attributes, including enhanced light-harvesting capacity, strong redox ability and different oxidation and reduction positions. In the present work, a novel ternary Z-scheme photocatalyst, i.e., Bi2WO6/C-dots/TiO2, has been prepared by a facile chemical wet technique. The prepared solar light-driven Z-scheme composite was characterized by many analytical and spectroscopic practices, including powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), N2 adsorption–desorption isotherm, Fourier-transform infrared spectroscopy (FT-IR), photoluminescence (PL) and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the Bi2WO6/C-dots/TiO2 composite was evaluated by studying the degradation of fluoroquinolone drug, levofloxacin under solar light irradiation. Almost complete (99%) decomposition of the levofloxacin drug was observed in 90 min of sunlight irradiation. The effect of catalyst loading, initial substrate concentration and pH of the reaction was also optimized. The photocatalytic activity of the prepared catalyst was also compared with that of bare Bi2WO6, TiO2 and TiO2/C-dots under optimized conditions. Scavenger radical trap studies and terephthalic acid (TPA) fluorescence technique were done to understand the role of the photo-induced active radical ions that witnessed the decomposition of levofloxacin. Based on these studies, the plausible degradation trail of levofloxacin was proposed and was further supported by LC-MS analysis

Polymer nano-composite coatings and films: modern insights and emerging strategies to lengthen the lifespan of fruits and vegetables

A definite worldwide shift towards healthier and more nutrient-dense meals has emerged in the past couple of decades. There exists an emerging need for efficient preservation solutions that can effectively mitigate the perishable nature due to the increasing interest in healthy and fresh food products. An efficient method for lengthening the post-harvest lifespan of whole as well as chopped vegetables and fruits is packaging, which includes plastic films and coatings, however plastic packaging has the shortcoming of being a significant environmental threat in nearly every nation. Therefore, sustainable alternatives to traditional food packaging comprise films and/or coatings composed of bio polymers. However, compared to conventional plastic packaging, these biopolymers, which come from nature, have shortcomings such as essential physio-chemical and mechanical qualities. These flaws are fixed by strengthening biopolymers with nanomaterials, which also gives the resulting nanocomposites useful features including antioxidant and/or antibacterial activity. These advances in biopolymer-based nanocomposite can be made with the application of both inorganic (eg., zinc oxide, montmorillonite) and organic (such as nanocellulose fibrils) nanomaterials. This review article discusses the worth of biopolymer coating and films reinforced with nanocomposites to package whole and sliced fruits and vegetables to enhance their lifespan

Green synthesis of manganese oxide nanoparticles for the electrochemical sensing of p-nitrophenol

Abstract Manganese oxide (MnO) NPs are widely used in contaminant sensing, drug delivery, data storage, catalysis and biomedical imaging. Green synthesis of NPs is important due to increased concern of environmental pollution. Green chemistry based synthesis of NPs is preferred due to its ecofriendly nature. In this study, MnO NPs of different sizes were synthesized in aqueous medium using clove, i.e., Syzygium aromaticum extract (CE) as reducing and stabilizing agents. These NPs were used for the electrochemical sensing of p-nitrophenol (PNP). The synthesis of MnO NPs was over in 30 min. MnO NPs of different sizes were obtained by varying metal ion concentration, metal ion volume ratio, CE concentration, CE volume ratio, and incubation temperature. Selectively, ~4 nm MnO NPs were used for electrochemical sensing of paranitrophenol. The MnO NPs modified gold electrodes detected PNP with good sensitivity, 0.16 µA µM−1 cm2. The limit of PNP detection was 15.65 µM. The MnO NPs prepared using CE based green chemistry approach is useful for PNP sensing. These NPs can also be useful for various in vivo applications in which the NPs come in human contact

rGO-WO₃ Heterostructure: Synthesis, Characterization and Utilization as an Efficient Adsorbent for the Removal of Fluoroquinolone Antibiotic Levofloxacin in an Aqueous Phase

Herein, the heterostructure rGO-WO3 was hydrothermally synthesized and characterized by HRTEM (high-resolution transmission electron microscopy), FESEM (field emission scanning electron microscopy), XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron microscopy), nitrogen physisorption isotherm, Raman, TGA (thermogravimetric analysis) and zeta potential techniques. The HRTEM and FESEM images of the synthesized nanostructure revealed the successful loading of WO3 nanorods on the surface of rGO nanosheets. The prepared heterostructure was utilized as an efficient adsorbent for the removal of a third-generation fluoroquinolone antibiotic, i.e., levofloxacin (LVX), from water. The adsorption equilibrium data were appropriately described by a Langmuir isotherm model. The prepared rGO-WO3 heterostructure exhibited a Langmuir adsorption capacity of 73.05 mg/g. The kinetics of LVX adsorption followed a pseudo-second-order kinetic model. The adsorption of LVX onto the rGO-WO3 heterostructure was spontaneous and exothermic in nature. Electrostatic interactions were found to have played a significant role in the adsorption of LVX onto the rGO-WO3 heterostructure. Thus, the prepared rGO-WO3 heterostructure is a highly promising material for the removal of emerging contaminants from aqueous solution

Rapid Solar-Light Driven Superior Photocatalytic Degradation of Methylene Blue Using MoS₂-ZnO Heterostructure Nanorods Photocatalyst

Herein, MoS2-ZnO heterostructure nanorods were hydrothermally synthesized and characterized in detail using several compositional, optical, and morphological techniques. The comprehensive characterizations show that the synthesized MoS2/ZnO heterostructure nanorods were composed of wurtzite hexagonal phase of ZnO and rhombohedral phase of MoS2. The synthesized MoS2/ZnO heterostructure nanorods were used as a potent photocatalyst for the decomposition of methylene blue (MB) dye under natural sunlight. The prepared MoS2/ZnO heterostructure nanorods exhibited ~97% removal of MB in the reaction time of 20 min with the catalyst amount of 0.15 g/L. The kinetic study revealed that the photocatalytic removal of MB was found to be in accordance with pseudo first-order reaction kinetics with an obtained rate constant of 0.16262 min&#8722;1. The tremendous photocatalytic performance of MoS2-ZnO heterostructure nanorods could be accredited to an effective charge transportation and inhibition in the recombination of photo-excited charge carriers at an interfacial heterojunction. The contribution of active species towards the decomposition of MB using MoS2-ZnO heterostructure nanorods was confirmed from scavenger study and terephthalic acid fluorescence technique

Solar light driven photocatalytic degradation of levofloxacin using TiO2/carbon-dot nanocomposites

This paper reports the synthesis of TiO2 quantum dots, carbon dots (C-dots), and TiO2/C-dots using facile sol-gel and hydrothermal methods. The synthesized quantum dots were further characterized in detail to understand their crystalline, structural, morphological, thermal and optical properties using various spectroscopic and analytical techniques. The characterization results confirmed that the prepared photocatalysts exhibited high crystallinity, purity and excellent optical properties. The morphological results indicated that the C-dots were uniformly distributed over the TiO2 quantum dots and nanocomposites have an average size of 12 nm. Furthermore, the prepared sample, i.e. TiO2/C-dots, was efficiently employed as a potential heterogeneous photocatalyst for solar light driven photocatalytic degradation of a fluoroquinolone antibiotic drug levofloxacin. To optimize the photocatalytic degradation experiments, various catalyst dose-dependent, pH-dependent, and initial drug-concentration dependent experiments were carried out. The photocatalytic experiments revealed almost complete photocatalytic degradation of levofloxacin (10 mg L-1) within 90 minutes of solar light illumination using the TiO2/C-dots under optimum conditions, whereas bare TiO2 showed only 66.5% degradation of the drug. Different commercial photocatalysts such as TiO2 PC-50 and TiO2 PC-500 were also used for comparing the photocatalytic efficiency of the synthesized photocatalyst. Furthermore, the stability of the photocatalyst was studied by performing recyclability experiments up to 5 cycles using the TiO2/C-dots, indicating that the nanocomposites could be reused without any significant loss. The TOC results indicated the simultaneous 53.4% mineralization and photocatalytic degradation of levofloxacin under optimized conditions. The enhanced photocatalytic activity of the nanocomposites was attributed to the presence of the C-dots in the system, which provided more active sites for the drug molecules and also restricted the recombination of charge carriers. The role of active radical species in the photocatalytic degradation of levofloxacin was also investigated. A photocatalytic degradation mechanism and pathway were also proposed

Visible-light driven photocatalytic degradation of brilliant green dye based on cobalt tungstate (CoWO4) nanoparticles

© 2018 Elsevier B.V. Herein, we report the successful surfactant free synthesis, characterization and visible light driven photocatalytic application of highly crystalline cobalt tungstate (CoWO4) nanoparticles. The synthesized nanoparticles were characterized by several techniques which revealed that CoWO4 exhibited monoclinic phase of Wolframite structure, possess high crystallinity and grown in very high density. As the tungstate nanomaterials are hardly investigated as visible light responsive photocatalyst for the removal of organic pollutants in aqueous phase, thus, in this paper the photocatalytic efficiency of cobalt tungstate nanoparticles was estimated by monitoring the degradation of brilliant green dye under visible light irradiation. Approximately 94% brilliant green dye was degraded within 120 min of visible light illumination. Hydroxyl radicals were held to be accountable for the excellent photocatalytic performance. The present study offers an innovative approach stating that metal tungstates can also be considered as proficient visible light responsive photocatalysts for the degradation of hazardous organic contaminants from aqueous phase