A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO3 using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10 h, and AgNPs showed characteristic surface plasmon resonance around 410 nm. Spherical nanoparticles of size less than 30 nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as-prepared AgNPs showed excellent catalytic activity in reduction of 4-nitrophenol to 4-aminophenol by NaBH4. By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated. 相似文献
Environmental Science and Pollution Research - There has been alarming depletion of manganese (Mn) reserves owing to the ongoing extensive mining operations for catering the massive industrial... 相似文献
• In situ preparation of FeNi nanoparticles on the sand via green synthesis approach.• Removal of tetracycline using GS-FeNi in batch and column study.• Both reductive degradation and sorption played crucial role the process.• Reusability of GS-FeNi showed about 77.39±4.3% removal on 4th cycle.• TC by-products after interaction showed less toxic as compared with TC. In this study, FeNi nanoparticles were green synthesized using Punica granatum (pomegranate) peel extract, and these nanoparticles were also formed in situ over quartz sand (GS-FeNi) for removal of tetracycline (TC). Under the optimized operating conditions, (GS-FeNi concentration: 1.5% w/v; concentration of TC: 20 mg/L; interaction period: 180 min), 99±0.2% TC removal was achieved in the batch reactor. The removal capacity was 181±1 mg/g. A detailed characterization of the sorbent and the solution before and after the interaction revealed that the removal mechanism(s) involved both the sorption and degradation of TC. The reusability of reactant was assessed for four cycles of operation, and 77±4% of TC removal was obtained in the cycle. To judge the environmental sustainability of the process, residual toxicity assay of the interacted TC solution was performed with indicator bacteria (Bacillus and Pseudomonas) and algae (Chlorella sp.), which confirmed a substantial decrease in the toxicity. The continuous column studies were undertaken in the packed bed reactors using GS-FeNi. Employing the optimized conditions, quite high removal efficiency (978±5 mg/g) was obtained in the columns. The application of GS-FeNi for antibiotic removal was further evaluated in lake water, tap water, and ground water spiked with TC, and the removal capacity achieved was found to be 781±5, 712±5, and 687±3 mg/g, respectively. This work can pave the way for treatment of antibiotics and other pollutants in the reactors using novel green composites prepared from fruit wastes. 相似文献
This study investigated the presence of total mercury (Hg) and organic mercury levels in the muscle of 19 common fresh water
fish species captured from river Ganges, West Bengal, India. The total mercury level found in our study may not cause any
toxic effect, but the methyl mercury (MeHg) level in some freshwater fish species was surprisingly very high and toxically
unacceptable. The results of mercury analysis in various specimens indicated that some fish muscles tended to accumulate high
levels of Hg, and approximately 50–84% of Hg was organic mercury. A strong positive correlation between mercury levels in
muscle with food habit and fish length (age) was found. Wallago attu possessed the highest amount of organic mercury in their muscle tissues, and it was 0.93 ± 0.61 μg Hg/g of wet weight. Whereas
in small-sized fishes Eutropiichthys murius, Puntius sarana, Cirrhinus mrigala, Mystus vittatus or Mystus gulio, and Tilapia mossambicus, it was below the detection limit. Contamination in Catla catla (0.32 ± 0.11), Anguilla bengalensis bengalensis (0.26 ± 0.07 μg Hg/g), Chitala chitala (0.25 ± 0.18), Rita rita (0.34 ± 0.14), and Ompok pabda (0.26 ± 0.04) was also above the 0.25 μg Hg/g of wet weight, the limit set by the PFA for the maximum level for consumption
of fish exposed to MeHg. Though in Labeo rohita (0.12 ± 0.03), Mastacembelus armatus (0.17 ± 0.02), Pangasius pangasius (0.12 ± 0.16), Bagarius bagarius (0.12 ± 0.01), and Clupisoma garua (0.1 ± 0.01), concentration was below the recommended level, in Lates calcarifer (0.23 ± 0.0) and Mystus aor (0.23 ± 0.1), it was threatening. Interestingly, a low concentration of Hg was found in post-monsoon samples. 相似文献
The effect of two fly ashes as soil amendment on the adsorption–desorption of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylphenyl)] and atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) was studied in alluvial and laterite soils. The adsorption data for both the herbicides fitted well the Freundlich equation, and Freundlich adsorption coefficient (Kf) increased with an increase of fly ash amount. Both the fly ashes differed in their extent to increase herbicide sorption, and the effect was different in different soils. Atrazine was sorbed more in the soils/soils?+?fly ash mixtures than the metolachlor. The Kf values showed significant correlation with the amount of fly ash amendment (correlation coefficient, R?>?0.982). The desorption isotherms also fitted the Freundlich equation, and desorption showed hysteresis which increased with an increase in the content of fly ash amendment. The free energy change (ΔG) indicated that the sorption process is exothermic, spontaneous, and physical in nature. The study has shown that fly ash as soil amendment significantly increased the sorption of metolachlor and atrazine, but the effect is soil- and fly ash-specific. 相似文献
The risk of cancer due to PCB exposure in humans is highly debated. In eastern Slovakia, high exposure of the population to organochlorines (especially PCBs) was associated with various disease and disorder pathways, viz., endocrine disruption, metabolic disorder & diabetes, and cancer, thereby disturbing several cellular processes, including protein synthesis, stress response, and apoptosis. We have evaluated a Slovak cohort (45-month children, at lower and higher levels of PCB exposure from the environment) for disease and disorder development to develop early disease cancer biomarkers that could shed new light on possible mechanisms for the genesis of cancers under such chemical exposures, and identify potential avenues for prevention.
Microarray studies of global gene expression were conducted from the 45-month-old children on the Affymetrix platform followed by Ingenuity Pathway Analysis (IPA®) to associate the affected genes with their mechanistic pathways. High-throughput qRT-PCR TaqMan low-density array (TLDA) was performed to further validate the selected genes on the whole blood cells of the most highly exposed children from the study cohort (n = 71).
TP53, MYC, BCL2, and LRP12 differential gene expressions suggested strong relationships between potential future tumor promotion and PCB exposure in Slovak children. The IPA analysis further detected the most important signaling pathways, including molecular mechanism of cancers, prostate cancer signaling, ovarian cancer signaling, P53 signaling, oncostatin M signaling, and their respective functions (viz., prostate cancer, breast cancer, progression of tumor, growth of tumor, and non-Hodgkin’s disease). The results suggest that PCB exposures, even at the early age of these children, may have lifelong consequences for the future development of chronic diseases.