Pure and Mg-doped self-assembled ZnO nano-particles for the enhanced photocatalytic degradation of 4-chlorophenol
01 Oct 2013-Journal of Environmental Sciences-china (J Environ Sci (China))-Vol. 25, Iss: 10, pp 2157-2167
TL;DR: The photocatalytic degradation of 4-chlorophenol (4-CP), a potent endocrine disrupting chemical in aqueous medium was investigated by both pure and Mg-doped ZnO NPs under UV-light irradiation in the present study.
Abstract: A novel self-assembled pure and Mg doped ZnO nano-particles (NPs) were successfully synthesized by a simple low temperature co-precipitation method. The prepared photocatalysts were characterized by X-ray diffraction, high resolution scanning electron microscopy, high resolution transmission electron microscopy, diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The results indicated that the prepared photocatalysts showed high crystallinity with a uniform size distribution of the NPs. The degradation of cholorphenols is highly mandatory in today's scenario as they are affecting the environment adversely. Thus, the photocatalytic degradation of 4-chlorophenol (4-CP), a potent endocrine disrupting chemical in aqueous medium was investigated by both pure and Mg-doped ZnO NPs under UV-light irradiation in the present study. The influence of the Mg content on the structure, morphology, PL character and photocatalytic activity of ZnO NPs were investigated systematically. Furthermore,the effect of different parameters such as 4-CP concentration, photocatalyst amount, pH and UV-light wavelength on the resulting photocatalytic activity was investigated.
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TL;DR: In this paper, the photo-degradation mechanisms of persistent organic pollutants (POPs) and the recent progress in ZnO nanostructured fabrication methods including doping, heterojunction and modification techniques as well as improvements of ZnOs as a photocatalyst are reviewed.
Abstract: Persistent organic pollutants (POPs) are carbon-based chemical substances that are resistant to environmental degradation and may not be completely removed through treatment processes. Their persistence can contribute to adverse health impacts on wild-life and human beings. Thus, the solar photocatalysis process has received increasing attention due to its great potential as a green and eco-friendly process for the elimination of POPs to increase the security of clean water. In this context, ZnO nanostructures have been shown to be prominent photocatalyst candidates to be used in photodegradation owing to the facts that they are low-cost, non-toxic and more efficient in the absorption across a large fraction of the solar spectrum compared to TiO 2 . There are several aspects, however, need to be taken into consideration for further development. The purpose of this paper is to review the photo-degradation mechanisms of POPs and the recent progress in ZnO nanostructured fabrication methods including doping, heterojunction and modification techniques as well as improvements of ZnO as a photocatalyst. The second objective of this review is to evaluate the immobilization of photocatalyst and suspension systems while looking into their future challenges and prospects.
1,551 citations
Additional excerpts
...Co-precipitation Endocrine disrupting chemicals 4-chlorophenol [170]...
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TL;DR: The green synthesis of NiO nanoparticles using Aegle marmelos as a fuel is reported and it is found that the cell viability of A549 cells was effectively reduced and it showed better antibacterial activity towards gram positive bacterial strains.
Abstract: In the present study, we report the green synthesis of NiO nanoparticles using Aegle marmelos as a fuel and this method is ecofriendly and cost effective. The plant Aegle marmelos is used in the field of pharmaceuticals to cure diseases like chronic diarrhea, peptic ulcers and dysentery in India for nearly 5 centuries. The as-prepared nanoparticles were confirmed as pure face centered cubic phase and single crystalline in nature by XRD. The formation of agglomerated spherical nanoparticles was shown by HR-SEM and HR-TEM images. The particle size calculated from HR-SEM was in the range 8-10 nm and it matches with the average crystallite size calculated from the XRD pattern. NiO shows intense emission peaks at 363 and 412 nm in its PL spectra. The band gap of 3.5 eV is observed from DRS studies and the formation of pure NiO is confirmed by FT-IR spectra. The as-prepared NiO nanoparticles show super paramagnetic behavior, when magnetization studies are carried out. It is then evaluated for cytotoxic activity towards A549 cell culture, antibacterial activity and photocatalytic degradation (PCD) of 4‑chlorophenol (4‑CP), which is known as the endocrine disrupting chemical (EDC). From the results, it is found that the cell viability of A549 cells was effectively reduced and it showed better antibacterial activity towards gram positive bacterial strains. It is also proved to be an efficient and stable photocatalyst towards the degradation of 4‑CP.
248 citations
Cites background from "Pure and Mg-doped self-assembled Zn..."
...The formation condition occurs at a pH, where the surface charge becomes zero so that there will be a generation of more %OH radicals and adsorption of more 4CP molecules on the catalyst surface [55]....
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TL;DR: In this article, a novel ZnO photocatalyst was synthesized by a green method using lemon juice and zinc acetate as precursors, and then the effect of sucrose addition on the initial precursor was investigated.
Abstract: A novel ZnO photocatalyst was synthesized by a green method using lemon juice and zinc acetate as precursors, and then the effect of sucrose addition on the initial precursors was investigated. The samples were characterized by field-emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, UV-visible, and photoluminescence analysis. The result showed that the as-obtained products with the mix of lemon juice (30 mL) and sucrose had a spherical morphology with the mean particle size of about 21.5 nm. The photocatalytic activity of this sample was tested for the degradation of methyl orange, methyl red and methylene blue solutions. The results also revealed the good photocatalytic activity for the degradation of these three organic dyes. Furthermore, as-synthesized sample was used in decolorization processes and the treatment of textile dyes (reactive blue 21).
155 citations
TL;DR: In this paper, the results of the photocatalytic degradation of bisphenol A (BPA) and nonylphenol (NP) in aqueous solutions under UV irradiation and in the presence of hydrogen peroxide (H2O2) were obtained using 1% Ag-doped ZnO.
137 citations
TL;DR: The antibacterial activities of the ZnO-coated fabric were investigated against some gram-positive and gram-negative bacteria such as Salmonella typhimurium, Klebsiella pneumonia, Escherichia coli, and Bacillus subtilis.
Abstract: Dirt and microorganisms are the major problems in textiles which can generate unpleasant odor during their growth. Here, zinc oxide (ZnO) nanoparticles prepared by sol-gel method were loaded on the cotton fabrics using spin coating technique to enhance their antimicrobial properties and water repellency. The effects of ZnO precursor concentration, precursor solution pH, number of coating runs, and Mg doping percent on the structures, morphologies, and water contact angles (WCA) of the ZnO-coated fabrics were addressed. At 0.5 M concentration and pH7, more homogeneous and smaller ZnO nanoparticles were grown along the preferred (0 0 2) direction and uniformly distributed on the fabric with a crystallite size 17.98 nm and dislocation density 3.09 × 10−3 dislocation/nm2. The substitution of Zn
2+
with Mg
2+
ions slightly shifted the (002) peak position to a higher angle. Also, the zeta potential and particle size distribution were measured for ZnO nanoparticle suspension. A superhydrophobic WCA = 154° was measured for the fabric that coated at 0.5 M precursor solution, pH 7, 20 runs and 0% Mg doping. Moreover, the antibacterial activities of the ZnO-coated fabric were investigated against some gram-positive and gram-negative bacteria such as Salmonella typhimurium, Klebsiella pneumonia, Escherichia coli, and Bacillus subtilis.
123 citations
References
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TL;DR: In this article, the photocatalytic activity of commercial ZnO powder has been investigated and compared with that of Degussa P25 TiO2 in terms of surface area, particle size and crystallinity.
1,458 citations
TL;DR: In this article, a wide gap II-VI semiconductor alloy, MgxZn1−xO, was proposed for the fabrication of heteroepitaxial ultraviolet light emitting devices based on ZnO.
Abstract: We propose a widegap II–VI semiconductor alloy, MgxZn1−xO, for the fabrication of heteroepitaxial ultraviolet light emitting devices based on ZnO. The c-axis oriented MgxZn1−xO films were epitaxially grown by pulsed laser deposition on ZnO epitaxial films and sapphire (0001) substrates using ceramic targets. Solid solution films were prepared with Mg content up to x=0.33, achieving a band gap of 3.99 eV at room temperature. MgO impurity phase segregated at x⩾0.36. Lattice constants of MgxZn1−xO films changed slightly (∼1%), increasing in a axis and decreasing in c-axis direction with increasing x. These films showed ultraviolet photoluminescence at energies from 3.36 (x=0) to 3.87 eV (x=0.33) at 4.2 K.
1,441 citations
TL;DR: Thioglycerol-capped luminescent CdS QDs discriminate between copper and zinc ions and are therefore suitable for the analysis of copper ions in biological samples in the presence of physiological concentrations of zinc ions.
Abstract: Water-soluble luminescent CdS quantum dots (QDs) capped by polyphosphate, l-cysteine, and thioglycerol were synthesized in aqueous solution. The ligands were found to have a profound effect on the luminesence response of CdS QDs to physiologically important metal cations. Polyphosphate-capped CdS QDs were sensitive to nearly all mono- and divalent cations, showing no ion selectivity. Conversely, thioglycerol-capped CdS QDs were sensitive to only copper and iron ions. Similar concentrations of physiologically relevant cations, such as zinc, sodium, potassium, calcium, and magnesium ions did not affect the luminescence of thioglycerol-capped CdS QDs. On the other hand, l-cysteine-capped CdS QDs were sensitive to zinc ions and insensitive to other physiologically important cations, such as copper, calcium, and magnium ions. To demonstrate the detection capability of these new ion probes, l-cysteine and thioglycerol-capped CdS QDs were used to detect zinc and copper ions in physiological buffer samples. The d...
891 citations
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816 citations
TL;DR: In this paper, the degradation of 2-phenylphenol (OPP) can be photocatalysed by TiO 2 and ZnO, and a mechanism is proposed for the photocatalytic transformation of OPP.
Abstract: The degradation of 2-phenylphenol (OPP), commonly used as fungicide, can be photocatalysed by TiO 2 and ZnO. The latter is a little more efficient but cannot be used in acidic solution. In both cases, the main identified photoproducts are hydroquinone (HQ), p -benzoquinone (BQ), phenylhydroquinone (PHQ), phenylbenzoquinone (PBQ), 2,2′- and 2,3-dihydroxybiphenyls (2,2′- and 2,3-BPh(OH) 2 ). The observed minor formation of 2-hydroxydibenzofuran is due to the photocyclisation of PBQ. The influence of various parameters is considered. The phototransformation of OPP is slightly favoured by increasing pH. It is enhanced by the addition of small amounts of H 2 O 2 , but it is inhibited by high concentrations of chloride, sulphate or nitrate. From the inhibiting effect of alcohols, it is deduced that the main degradation pathway involves hydroxyl radicals, but a direct oxidation by positive holes h + is probably not negligible. The observed slow photodegradation of ZnO in unbuffered solution is attributed to an electrochemical process. A mechanism is proposed for the photocatalytic transformation of OPP.
572 citations