Bok choy (Brassica rapa) grown in copper oxide nanoparticles-amended soils exhibits toxicity in a phenotype-dependent manner: Translocation, biodistribution and nutritional disturbance.

The comparative toxicity of nano/bulk cupric oxide (CuO) and ionic copper (Cu) in Rosie and Green bok choy (Brassica rapa) varieties, with higher and lower anthocyanin contents, respectively, was investigated. Both phenotypes were cultivated for 70 days in natural soil amended with nano CuO (nCuO), bulk CuO (bCuO), and Cu chloride (CuCl2) at 75, 150, 300, and 600 mg Cu/kg soil. Essential elements in tissues, agronomical parameters, chlorophyll content, and Cu distribution in leaf were determined. In both varieties, nCuO treatments significantly increased Cu uptake in roots, compared with bCuO and CuCl2 (p ≤ 0.05). At all treatment concentrations, Rosie variety had more Cu than Green. More physiological impairments such as chlorophyll and leaf biomass reduction were observed in treated-Rosie varieties, compared to Green plants. The adverse effects were higher in nCuO-treated plants than their bCuO- or ionic Cu-exposed counterparts. Different distribution patterns of the translocated Cu in leaf midrib and parenchyma depended on particle size and plant phenotype, as demonstrated by two-photon microscopy. The different effects of CuO-based compounds in Rosie and Green varieties may be related to the anthocyanin content. These findings help to understand the factors involved in nanoparticles uptake and translocation to plant edible parts.

Development of photocatalytic paint based on TiO2 and photopolymer resin for the degradation of organic pollutants in water.

While the use of TiO2 nanoparticles in the form of slurry/suspension requires energy-intensive separation processes, its immobilization in solid support may open new opportunities in the area of sustainable water treatment technologies. In this study, a novel method for the development of photocatalytic paint based on TiO2 nanoparticles and acrylate-based photopolymer resin is reported. The paint (TiO2@polymer) was applied on substrates such as plastic petri dish and glass jar, which was polymerized/solidified by ultraviolet light irradiation. The painted petri dish and glass jar were used for the photocatalytic degradation of model organic pollutants viz. methyl orange (MO), methylene blue (MB), and indole in deionized water, simulated fresh drinking water, and tap water matrices. The photocatalytic degradation studies were performed under sunlight and UV-B light were used for. The sunlight-assisted photocatalytic degradation of MO and MB was found to be faster and more efficient than the UV-B light-assisted ones. Under UV-B light irradiation, it took 120 min to degrade about 80% of 6 ppm MB solution, whereas under sunlight irradiation it took 60 min to degrade about 90% of the same MB solution. The photocatalytic paint generated hydroxyl radical (·OH) under the UV-B and sunlight irradiation, which was studied by the terephthalic acid fluorescence tests. Further, the potential release of TiO2 during the exposure to UV irradiation was studied by single particle ICP-MS analysis.

Sustainable synthesis and remarkable adsorption capacity of MOF/graphene oxide and MOF/CNT based hybrid nanocomposites for the removal of Bisphenol A from water.

A series of novel absorbents based on Cu-BDC MOFs decorated over graphene oxide (GrO) and carbon nanotubes (CNTs) hybrid nanocomposites, namely Cu-BDC@GrO and Cu-BDC@CNT, are synthesized via a facile and one-pot green solvothermal method for water remediation. The nanocomposites were characterized by XRD, TEM, SEM, EDS, Raman, FTIR, TGA, XPS, Zetasizer and ICP-OES instruments. XRD results confirmed the high crystalline structure of the synthesized hybrid nanocomposites. Morphological analysis by SEM and TEM verified the successful decoration of nano-sized Cu-BDC MOFs over GrO and CNT platforms; whereas, EDS and XPS analysis confirmed the presence of all components in the hybrid nanocomposites. Bisphenol A was used in this study as a model organic pollutant that is sometimes present in the industrial wastewater to test the adsorption capacity of the prepared hybrid nanomaterials toward their removal from water. The hybrid nanomaterials showed remarkable adsorption capacity of 182.2 and 164.1 mg/g toward the removal of BPA, which was several times higher than that of 60.2 mg/g for Cu-BDC MOF itself. The Langmuir, Freundlich, Temkin and D-R isotherm models were applied to analyze the experimental data and the results revealed that the Freundlich model describes the experimental data best. A kinetic study was carried out and it showed that the prepared nanomaterials could remove maximum amount of BPA from water in 30 min. The pseudo-first order, pseudo-second order and intra-particle diffusion models were applied to evaluate the kinetic data and the results suggested that the kinetics data could be well fitted to the pseudo-second order kinetic model. Additionally, the BAP adsorption process onto the hybrid nanocomposites was spontaneous and exothermic. The π-π interactions between the BPA and hybrid nanomaterials played a vital role during the BPA adsorption process. The higher adsorption capacity and water stability makes them a good candidate for water remediation applications.