Zinc oxide nanoparticles have been synthesized sonochemically from zinc acetate solution in aqueous methanol, ethanol and iso-propanol containing about 5 volume% of alcohol. Characterization with FESEM, XRD, AFM and BET surface area shows that the synthesized particles differ in shape and size. ZnO synthesized using isopropanol was observed to be the most crystalline one. The synthesized nanoparticles were used for the photocatalytic reduction of hexavalent chromium in aqueous medium under solar radiation. It was observed that the initial reduction rates varied with the difference in morphology of ZnO crystallites. © 2011 Elsevier B.V. All rights reserved.

SAMPA CHAKRABARTI

Chemical Engineering

P BANERJEE

S MAITRA

B K DUTTA

Fulltext

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Ultrasonics Sonochemistry

Iron-doped zinc oxide nanoparticles have been synthesized sonochemically from aqueous acetyl acetonate precursors of different proportions. Synthesized nanoparticles were characterized with UV-vis spectroscopy, X-ray diffraction and microscopy. Influences of precursor mixture on the characteristics have been examined and modeled. Linear correlations have been proposed between dopant dosing, extent of doping and band gap energy. Experimental data corroborated with the proposed models. © 2015 Elsevier Ltd.

Materials Research Bulletin

Sonochemically synthesized iron-doped zinc oxide nanoparticles: Influence of precursor composition on characteristics

Multifunctional cotton fabric has been prepared by pad-dry-coating with sonochemically synthesized zinc oxide nanoparticles. The uniqueness of sonochemical synthesis is that it synthesizes without alkali at near neutral pH and hence the cotton fabric is exposed to less chemical stress. As a result of coating, the fabric shows enhanced mechanical strength, water and stain repellence, antimicrobial properties, UV-blocking capacity and self-cleaning characteristics compared to the uncoated fabric. The self-cleaning property was tested with Trypan Blue dye under sunlight. The attempt of quantifying the self-cleaning process with the rate of decolorization is a novel one. It was observed that about 69% of the colour was removed when the coated fabric was exposed to sunlight for 3 h and 30 min. The fading of colour followed pseudo-first-order kinetics. © 2014 The Textile Institute.

Journal of the Textile Institute

Preparation and characterization of multifunctional cotton fabric by coating with sonochemically synthesized zinc oxide nanoparticle-flakes and a novel approach to monitor its self-cleaning property

Hexavalent chromium is more toxic and carcinogenic compared to its trivalent counterpart. Hexavalent chromium can be photocatalytically reduced to trivalent one using zinc oxide semiconductor and solar or UV radiation as light source. But an important ecological aspect is whether the net toxicity decreases after the photocatalytic process. In the present work, we have selected Anabaena flos-aquae as the model organism and examined whether the net toxicity to which it has been exposed in water decreases after photocatalytic reduction of hexavalent chromium using ZnO semiconductor as photocatalyst. We have studied the cumulative toxicities of both chromium (before and after treatment) and ZnO (both nano and micro) separately and as a suspension of ZnO in chromium. Quantitative cell surface roughness analysis was conducted using AFM to confirm the changes in cell surface properties. © 2012 Elsevier Inc.

Ecotoxicology and Environmental Safety

Ecotoxicological impact of sunlight assisted photoreduction of hexavalent chromium present in wastewater with zinc oxide nanoparticles on common Anabaena flos-aquae

Low cost, environmentally friendly and industrial-scale approaches for the synthesis of anti-counterfeiting and antibacterial materials are a challenging task. The current research reports novel and inexpensive approaches for the synthesis of zinc oxide nanostructures (ZnO-NSs) using Mini Submersible Pump (MSP) assisted sonochemical reactors. Zinc oxide nanoleaves (ZnO-NLs) were synthesized using MSP assisted sonochemical mixing reactor at gram-scale (4 g). Zinc oxide nanoparticles (ZnO-NPs) were synthesized using MSP assisted sonochemical flow loop reactor at gram-scale (11.5 g). Synthesized ZnO-NSs were characterized by UV–visible spectroscopy, fluorescence spectroscopy, XRD, FTIR, TGA, BET, FEG-SEM, and FEG-TEM. Bare ZnO-NPs and ZnO-NPs coated cotton fabric showed high antibacterial activity against diseases causing Gram-positive bacteria Staphylococcus aureus. Based on the UV fluorescence property of the ZnO-NLs, invisible security ink was developed for anti-counterfeiting applications. The invisible security ink was tested as a rubber stamp and fountain pen inks which were found to be stable on the various kinds of microporous papers. As compared to our previously reported method, disperser assisted sonochemical approach for ZnO-NLs synthesis; the current approach reduces the cost of equipment used from ∼1700 to 4 USD. Both reactors are designed simply (less complicated), based on an environmentally friendly approach, highly scalable, increases the effectiveness of the sonochemical technique and suitable for industrial applications. © 2018 Elsevier B.V.

Mini submersible pump assisted sonochemical reactors: Large-scale synthesis of zinc oxide nanoparticles and nanoleaves for antibacterial and anti-counterfeiting applications

Nanotechnology for Environmental Engineering

Removal of chromium from industrial effluents using nanotechnology: a review

Disposal of waste plastics imposes serious problems to the environmentalists, since plastics are non-biodegradable and emit carcinogenic gases when incinerated. In a country like India, where solar energy is abundantly available, semiconductor photo catalysis may be a clean and economic technology to combat such a problem. In the present work we addressed to the problem of degrading polyvinyl chloride (PVC) by photo catalysis by exposing a PVC-ZnO composite film to solar radiation as well as to artificial UV radiation in presence of water and air. Degradation in the two processes has been compared. The surface morphology as well as the FTIR spectroscopy of the irradiated film has been critically examined. The degradation was measured by weight loss data and was found to follow a pseudo-first order rate equation. The various parameters studied were loading of the semiconductor and intensity of UV radiation. A possible mechanism has been suggested and the corresponding rate equation has been modeled. The model has been validated by the experimental data. © 2010 Elsevier Ltd. All rights reserved.

Solar Energy

Photocatalytic degradation of PVC-ZnO composite film under tropical sunlight and artificial UV radiation: A comparative study

Common sources of chromium in wastewater are electroplating and leather industries. Hexavalent chromium is more toxic and carcinogenic compared to its trivalent counterpart. Conversion of Cr(VI) to Cr(III) in an aqueous medium by photocatalytic reduction using UV radiation and ZnO semiconductor catalyst has been investigated using potassium dichromate as the model compound. Effects of the process parameters such as ZnO loading (0-3 g/L) and intensity of UV radiation (0-125 W medium pressure Hg vapour lamp) on photocatalytic reduction were investigated. Initial concentration of substrate solution was varied from 40 to 120 mg/L. A comparison of the performance of the ZnO photocatalyst achieved in this study with that reported in the literature for photocatalytic and conventional processes is presented. The initial rate of the photochemical method was found to be independent of the concentration of potassium dichromate. Methanol was added as a hole scavenger for enhancement of the photo-reduction. Initial rate of photo-reduction was found to be independent of the concentration of methanol above a particular value. A probable mechanism and the corresponding kinetic model have been proposed for the photo-reduction and tested by experimental results. An alternative rate equation based on the LHHW model compares well with the mechanistic rate equation. © 2009 Elsevier B.V. All rights reserved.

Journal	Data powered by TypesetUltrasonics Sonochemistry
Publisher	Data powered by TypesetElsevier B.V.
ISSN	1350-4177
Open Access	No