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Experimental and first-principles DFT studies on the band gap behaviours of microsized and nanosized Zn(1-x)MnxO materials

Kasim MF, Darman AKAB, Yaakob MK, Badar N, Kamarulzaman N

Phys Chem Chem Phys, 2019 Sep 11;21(35):19126-19146.
PMID: 31432825 DOI: 10.1039/c9cp01664c

In this study, nano- and microsized zinc oxide (ZnO) materials were doped with different manganese (Mn) contents (1-5 mol%) via a simple sol-gel method. The structural, morphological, optical and chemical environments of the materials were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), UV-visible spectroscopy (UV-vis) and X-ray photoelectron spectroscopy (XPS). XRD results revealed that all synthesised materials were pure and single phased with a hexagonal wurtzite structure of ZnO. However, at a low annealing temperature, a nanorod-like shape can be obtained for all Zn(1-x)MnxO materials. In addition, EDX spectra confirmed the presence of Mn in the ZnO lattice and the atomic percentage was nearly equal to the calculated stoichiometry. UV-vis spectroscopy further revealed that materials in nano size exhibited band gap widening with an increase of the Mn content in the ZnO lattice. In contrast, micron state materials exhibited band gap narrowing with increasing Mn content up to 3% and then begin to widen when Mn > 3%. This is because the band gaps of these materials are affected by the dimensions of the crystals and the Mn content in the materials. Furthermore, XPS results revealed the existence of multiple states of Mn in all synthesised materials. By combining the information obtained from UV-vis and the XPS valence band, shifting in the valence band maximum (VBM) and conduction band minimum (CBM) was observed. Based on XPS results, the calculation of density functional theory studies revealed that the presence of Mn2+, Mn3+, and Mn4+ ions in the materials influences the band gap changes. It was also revealed that the nanosized Zn0.99Mn0.01O exhibited a higher photocatalytic activity than the other samples for degrading methylene blue (MB) dyes, owing to its smallest crystallite size.

Matched MeSH terms: Zinc; Zinc Oxide
Fulltext Enhanced Cycling Performance of Rechargeable Zinc-Air Flow Batteries Using Potassium Persulfate as Electrolyte Additive

Khezri R, Hosseini S, Lahiri A, Motlagh SR, Nguyen MT, Yonezawa T, et al.

Int J Mol Sci, 2020 Oct 02;21(19).
PMID: 33023274 DOI: 10.3390/ijms21197303

Zinc-air batteries (ZABs) offer high specific energy and low-cost production. However, rechargeable ZABs suffer from a limited cycle life. This paper reports that potassium persulfate (KPS) additive in an alkaline electrolyte can effectively enhance the performance and electrochemical characteristics of rechargeable zinc-air flow batteries (ZAFBs). Introducing redox additives into electrolytes is an effective approach to promote battery performance. With the addition of 450 ppm KPS, remarkable improvement in anodic currents corresponding to zinc (Zn) dissolution and limited passivation of the Zn surface is observed, thus indicating its strong effect on the redox reaction of Zn. Besides, the addition of 450 ppm KPS reduces the corrosion rate of Zn, enhances surface reactions and decreases the solution resistance. However, excess KPS (900 and 1350 ppm) has a negative effect on rechargeable ZAFBs, which leads to a shorter cycle life and poor cyclability. The rechargeable ZAFB, using 450 ppm KPS, exhibits a highly stable charge/discharge voltage for 800 cycles. Overall, KPS demonstrates great promise for the enhancement of the charge/discharge performance of rechargeable ZABs.

Matched MeSH terms: Zinc/chemistry*
Fulltext Can Zn Be a Critical Element in COVID-19 Treatment?

Rahman MT, Idid SZ

Biol Trace Elem Res, 2021 Feb;199(2):550-558.
PMID: 32458149 DOI: 10.1007/s12011-020-02194-9

The current COVID-19 pandemic caused by SARS-CoV-2 has prompted investigators worldwide to search for an effective anti-viral treatment. A number of anti-viral drugs such as ribavirin, remdesivir, lopinavir/ritonavir, antibiotics such as azithromycin and doxycycline, and anti-parasite such as ivermectin have been recommended for COVID-19 treatment. In addition, sufficient pre-clinical rationale and evidence have been presented to use chloroquine for the treatment of COVID-19. Furthermore, Zn has the ability to enhance innate and adaptive immunity in the course of a viral infection. Besides, Zn supplement can favour COVID-19 treatment using those suggested and/or recommended drugs. Again, the effectiveness of Zn can be enhanced by using chloroquine as an ionophore while Zn inside the infected cell can stop SARS-CoV-2 replication. Given those benefits, this perspective paper describes how and why Zn could be given due consideration as a complement to the prescribed treatment of COVID-19.

Matched MeSH terms: Zinc/therapeutic use*
Fulltext Developing Conductive Highly Ordered Zinc Oxide Nanorods by Acetylacetonate-Assisted Growth

A Karim SS, Takamura Y, Tue PT, Tung NT, Kazmi J, Dee CF, et al.

Materials (Basel), 2020 Mar 04;13(5).
PMID: 32143385 DOI: 10.3390/ma13051136

Highly ordered vertically grown zinc oxide nanorods (ZnO NRs) were synthesized on ZnO-coated SiO2/Si substrate using zinc acetylacetonate hydrate as a precursor via a simple hydrothermal method at 85 °C. We used 0.05 M of ZnO solution to facilitate the growth of ZnO NRs and the immersion time was varied from 0.5 to 4 h. The atomic force microscopy revealed the surface roughness of ZnO seed layer used to grow the ZnO NRs. The morphology of vertically grown ZnO NRs was observed by field emission scanning electron microscopy. X-ray diffraction examination and transmission electron microscopy confirmed that the structure of highly ordered ZnO NRs was crystalline with a strong (002) peak corresponded to ZnO hexagonal wurtzite structure. The growth of highly ordered ZnO NRs was favorable due to the continuous supply of Zn2+ ions and chelating agents properties obtained from the acetylacetonate-derived precursor during the synthesis. Two-point probe current-voltage measurement and UV-vis spectroscopy of the ZnO NRs indicated a resistivity and optical bandgap value of 0.44 Ω.cm and 3.35 eV, respectively. The photoluminescence spectrum showed a broad peak centered at 623 nm in the visible region corresponded to the oxygen vacancies from the ZnO NRs. This study demonstrates that acetylacetonate-derived precursors can be used for the production of ZnO NRs-based devices with a potential application in biosensors.

Matched MeSH terms: Zinc; Zinc Oxide
Green synthesis of zinc oxide nanoparticles using Phoenix dactylifera waste as bioreductant for effective dye degradation and antibacterial performance in wastewater treatment

Rambabu K, Bharath G, Banat F, Show PL

J Hazard Mater, 2021 01 15;402:123560.
PMID: 32759001 DOI: 10.1016/j.jhazmat.2020.123560

Production of multi-functional zinc oxide nanoparticles (ZnO-NPs) for wastewater treatment through green-approaches is a desirable alternative for conventional synthesis routes. Biomass waste valorization for nanoparticles synthesis has received increased research attention. The present study reports date pulp waste (DPW) utilization as an effective bio-reductant for green-synthesis of ZnO-NPs. A simple and eco-friendly process with low reaction time and calcination temperature was adopted for DPW mediated ZnO-NPs (DP-ZnO-NPs) synthesis. Microscopic investigations of DP-ZnO-NPs confirmed the non-agglomeration and spherical nature of particles with mean diameter of 30 nm. EDX and XPS analysis defined the chemical composition and product purity of DP-ZnO-NPs. UV and photoluminescence studies exhibited surface plasmonic resonance at 381 nm and fluorescent nature of DP-ZnO-NPs. FTIR studies established a formation mechanism outline for DP-ZnO-NPs. XRD and Raman investigations confirmed the crystalline and hexagonal wurtzite phase of DP-ZnO-NPs. DSC/TG analysis displayed the thermal stability of DP-ZnO-NPs with <10 wt% loss upto 700 °C. Photocatalytic degradation of hazardous methylene blue and eosin yellow dyes using DP-ZnO-NPs, showed rapid decomposition rate with 90 % degradation efficiency. Additionally, DP-ZnO-NPs demonstrated significant antibacterial effects on various pathogenic bacteria in terms of zone-of-inhibition measured by disc-diffusion method. Thus, the as-prepared DP-ZnO-NPs is suitable for industrial wastewater treatment.

Matched MeSH terms: Zinc Oxide*
Fulltext Comparative Evaluation of Antifungal Efficacy of Five Root Canal Sealers against Clinical Isolates of Candida albicans: A Microbiological Study

Singh S, Srivastava B, Gupta K, Gupta N, Singh R, Singh S

Int J Clin Pediatr Dent, 2020 8 4;13(2):119-123.
PMID: 32742086 DOI: 10.5005/jp-journals-10005-1718

Aim and objective: The aim of this study was to evaluate and compare the antifungal efficacy of MTA Fillapex, Metapex, zinc oxide eugenol cement, Endomethasone, and Endoflas against Candida albicans.
Materials and methods: Root canal exudates of 30 patients were tested against MTA Fillapex (Angelus), Metapex (BioMed), zinc oxide eugenol (Deepak Enterprise), Endomethasone (Septodont), Endoflas FS (Sanlor Laboratories), MTA (Angelus) (positive control), and glycerine (negative control). Children with failed endodontic cases were included in the study. Tube dilution and agar diffusion methods were used to check the antifungal efficacy of the root canal sealers. In tube dilution method, 24-well culture plates containing freshly mixed material along with Candida albicans were used. Wells containing MTA (Angelus) along with Sabouraud dextrose agar and Candida albicans served as positive control while glycerine along with Sabouraud dextrose agar and Candida albicans served as negative control. All plates were incubated at 37°C for 24 hours. Growth of the fungi was monitored after 24 hours by the presence of the turbidity. The samples were recultured to test the experimental material using agar well diffusion method, and the Petri plates were incubated for 24 hours and 72 hours. Zone of inhibition was measured after respective time period. Paired t test was used for the data analysis.
Results: It was seen in tube dilution method Endomethasone showed least turbidity while maximum was shown by Metapex; similar results were seen in case of agar well diffusion method in which largest zone of inhibition was shown by Endomethasone while smallest was by Metapex.
Conclusion: It was concluded that Endomethasone showed maximum efficacy against Candida albicans as compared to Metapex.
How to cite this article: Singh S, Srivastava B, Gupta K, et al. Comparative Evaluation of Antifungal Efficacy of Five Root Canal Sealers against Clinical Isolates of Candida albicans: A Microbiological Study. Int J Clin Pediatr Dent 2020;13(2):119-123.

Matched MeSH terms: Zinc Oxide; Zinc Oxide-Eugenol Cement
Fulltext Comparative Evaluation of pH and In Vitro Cytotoxicity of Zinc Oxide-Ozonated Eugenol and Conventional Zinc Oxide Eugenol as Endodontic Sealers

Ravivarman C, Jeyasenthil A, Ajay R, Nilofernisha N, Karthikeyan R, Rajkumar D

J Pharm Bioallied Sci, 2020 Aug;12(Suppl 1):S73-S77.
PMID: 33149434 DOI: 10.4103/jpbs.JPBS_21_20

Background: Eugenol released from zinc oxide eugenol (ZOE)-based sealants may cause irritation to the periapical tissues and has cytotoxic potential. Ozone therapy has numerous clinical applications with humans because of its bactericidal action, detoxifying effect, stimulation of angiogenesis, and wound-healing capacity. Therefore ozone can be incorporated in ZOE sealer to exploit these properties.
Materials and Methods: Eugenol was ozonated using ozonator machine and the samples were divided into two groups: Group I: zinc oxide eugenol (n = 10) and Group II: zinc oxide-ozonated eugenol (OZOE; n = 10). The pH of the fresh sealer samples and the set samples was measured using calibrated pH meter after predetermined time intervals. Cytotoxicity of the set sealer was evaluated on mouse L929 fibroblasts using cellular metabolic assay.
Results: pH of the samples in Group II was higher when compared to Group I. Group II showed higher cell viability than the Group I.
Conclusion: OZOE sealers can be used as an alternative to the conventional ZOE sealers.

Matched MeSH terms: Zinc Oxide; Zinc Oxide-Eugenol Cement
Cd and Zn concentrations in the straits of Malacca and intertidal sediments of the west coast of Peninsular Malaysia

Yap CK, Ismail A, Tan SG

Mar Pollut Bull, 2003 Oct;46(10):1349-53.
PMID: 14550348
Matched MeSH terms: Zinc/analysis*
The effect of temperature change on the working and setting time of two luting cements

Abdullah H, Pearson GJ

Asian J Aesthet Dent, 1993 Jul;1(2):91-4.
PMID: 7921802

The effect of temperature change on the working and setting time of a glass ionomer luting cement and a resin luting cement was measured using the oscillating rheometer. The time taken for each cement to set was calculated from the chart recordings. It was observed that as the temperature increased, the working and setting time of both materials decreased. However, the reduction was much more marked for the dual curing resin cement.

Matched MeSH terms: Zinc Oxide/chemistry*
Heavy metal contents in coastal water fishes of West Malaysia

Babji AS, Embong MS, Woon WW

Bull Environ Contam Toxicol, 1979 Dec;23(6):830-6.
PMID: 519067
Matched MeSH terms: Zinc/analysis
Fulltext Influence of La3+ Substitution on Structure, Morphology and Magnetic Properties of Nanocrystalline Ni-Zn Ferrite

Dasan YK, Guan BH, Zahari MH, Chuan LK

PLoS One, 2017;12(1):e0170075.
PMID: 28081257 DOI: 10.1371/journal.pone.0170075

Lanthanum substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5LaxFe1-xO4; 0.00 ≤x≤ 1.00) synthesized by sol-gel method were presented. X-ray diffraction patterns reveal the typical single phase spinel cubic ferrite structure, with the traces of secondary phase for lanthanum substituted nanocrystals. In addition, the structural analysis also demonstrates that the average crystallite size varied in the range of 21-25 nm. FTIR spectra present the two prominent absorption bands in the range of 400 to 600 cm-1 which are the fingerprint region of all ferrites. Surface morphology of both substituted and unsubstituted Ni-Zn ferrite nanoparticle samples was studied using FESEM technique and it indicates a significant increase in the size of spherical shaped particles with La3+ substitution. Magnetic properties of all samples were analyzed using vibrating sample magnetometer (VSM). The results revealed that saturation magnetization (Ms) and coercivity (Hc) of La3+ substituted samples has decreased as compared to the Ni-Zn ferrite samples. Hence, the observed results affirm that the lanthanum ion substitution has greatly influenced the structural, morphology and magnetic properties of Ni-Zn ferrite nanoparticles.

Matched MeSH terms: Zinc/chemistry
Zinc accelerates dengue virus type 2-induced apoptosis in Vero cells

Shafee N, AbuBakar S

FEBS Lett, 2002 Jul 31;524(1-3):20-4.
PMID: 12135735

Dengue virus type 2 (DENV-2) infection induced apoptotic cellular DNA fragmentation in Vero cells within 8 days of infection. The addition of high concentrations of extracellular Zn(2+) but not Ca(2+), Mg(2+) or Mn(2+) to the cell culture medium hastened the detection of apoptosis to within 4 h after infection. No apoptotic cellular DNA fragmentation was detected in the cell culture treated with Zn(2+) alone or infected with heat- or ultraviolet light-inactivated DENV-2 in the presence of Zn(2+). These results suggest that (i) apoptosis is induced in African green monkey kidney cells infected with live DENV-2 and (ii) the addition of high extracellular Zn(2+) accelerates detection of apoptosis in the DENV-2-infected cells.

Matched MeSH terms: Zinc/pharmacology*
Fulltext Structural, Optical and Antibacterial Efficacy of Pure and Zinc-Doped Copper Oxide against Pathogenic Bacteria

Khalid A, Ahmad P, Alharthi AI, Muhammad S, Khandaker MU, Rehman M, et al.

Nanomaterials (Basel), 2021 Feb 10;11(2).
PMID: 33578945 DOI: 10.3390/nano11020451

Copper oxide and Zinc (Zn)-doped Copper oxide nanostructures (CuO-NSs) are successfully synthesized by using a hydrothermal technique. The as-obtained pure and Zn-doped CuO-NSs were tested to study the effect of doping in CuO on structural, optical, and antibacterial properties. The band gap of the nanostructures is calculated by using the Tauc plot. Our results have shown that the band gap of CuO reduces with the addition of Zinc. Optimization of processing conditions and concentration of precursors leads to the formation of pine needles and sea urchin-like nanostructures. The antibacterial properties of obtained Zn-doped CuO-NSs are observed against Gram-negative (Pseudomonasaeruginosa,Klebsiellapneumonia,Escherichiacoli) and Gram-positive (Staphylococcusaureus) bacteria via the agar well diffusion method. Zn doped s are found to have more effective bacterial resistance than pure CuO. The improved antibacterial activity is attributed to the reactive oxygen species (ROS) generation.

Matched MeSH terms: Zinc; Zinc Oxide
Fulltext Enhancing Microwave Absorbing Properties of Nickel-Zinc-Ferrite with Multi-walled Carbon Nanotubes (MWCNT) Loading at Higher Gigahertz Frequency

Fadzidah Mohd Idris, Khamirul Amin Matori, Idza Riati Ibrahim, Rodziah Nazlan, Mohd Shamsul Ezzad Shafie

Malaysian Journal of Science, Health & Technology, 2021;7(1):1-7.
MyJurnal

The rapid growth of electronic systems and devices operating within the gigahertz (GHz) frequency range has increased electromagnetic interference. In order to eliminate or reduce the spurious electromagnetic radiation levels more closely in different applications, there is strong research interest in electromagnetic absorber technology. Moreover, there is still a lack of ability to absorb electromagnetic radiation in a broad frequency range using thin thickness. Thus, this study examined the effect of incorporating magnetic and dielectric materials into the polymer matrix for the processing of radar absorbing materials. The experiment evaluated the sample preparation with different weight percentages of multi-walled carbon nanotubes (MWCNT) mixed with Ni0.5Zn0.5Fe2O4 (Nickel-Zinc-Ferrite) loaded into epoxy (P) as a matrix. The prepared samples were analysed by examining the reflectivity measurements in the 8 – 18 GHz frequency range and conducting a morphological study using scanning electron microscopy analyses. The correlation of the results showed that different amounts of MWCNT influenced the performance of the microwave absorber. As the amount of MWCNTs increased, the reflection loss (RL) peak shifted towards a lower frequency range and the trend was similar for all thicknesses. The highest RL was achieved when the content of MWCNTs was 2 wt% with a thickness of 2 mm with an RL of – 14 dB at 16 GHz. The 2.5 GHz bandwidth corresponded to the RL below -10 dB (90% absorption) in the range of 14.5 – 17 GHz. This study showed that the proposed experimental route provided flexible absorbers with suitable absorption values by mixing only 2 wt% of MWCNTs.

Matched MeSH terms: Zinc; Zinc Compounds
Fulltext Alleviation of diabetic nephropathy by zinc oxide nanoparticles in streptozotocin-induced type 1 diabetes in rats

Alomari G, Al-Trad B, Hamdan S, Aljabali AAA, Al Zoubi MS, Al-Batanyeh K, et al.

IET Nanobiotechnol, 2021 Jul;15(5):473-483.
PMID: 34694755 DOI: 10.1049/nbt2.12026

This study examines the effect of nanoparticles with zinc oxides (ZnONPs) on diabetic nephropathy, which is the primary cause of mortality for diabetic patients with end-stage renal disease. Diabetes in adult male rats was induced via intraperitoneal injection of streptozotocin. ZnONPs were intraperitoneally administered to diabetic rats daily for 7 weeks. Diabetes was associated with increases in blood glucose level, 24-h urinary albumin excretion rate, glomerular basement membrane thickness, renal oxidative stress markers, and renal mRNA or protein expression of transforming growth factor-β1, fibronectin, collagen-IV, tumour necrosis factor-α and vascular endothelial growth factor-A. Moreover, the expression of nephrin and podocin, and the mRNA expression of matrix metalloproteinase-9 were decreased in the diabetic group. These changes were not detected in the control group and were significantly prevented by ZnONP treatment. These results provide evidence that ZnONPs ameliorate the renal damage induced in a diabetic rat model of nephropathy through improving renal functionality; inhibiting renal fibrosis, oxidative stress, inflammation and abnormal angiogenesis; and delaying the development of podocyte injury. The present findings may help design the clinical application of ZnONPs for protection against the development of diabetic nephropathy.

Matched MeSH terms: Zinc Oxide*
Fulltext SYNTHESIS OF ZINC OXIDE NANOPARTICLES BY USING ALOE VERA LEAF EXTRACT AS PONTENTIAL ANODE MATERIAL IN LITHIUM ION BATTERY

SITI RABIATUL ADAWIYAH MAZLI, HANIS MOHD YUSOFF, NURUL HAYATI IDRIS

UMT Journal of Undergraduate Research, 2020;2(2):0-0.
MyJurnal

Synthesis of nanoparticles by using plant have sparked interest among researchers due to environmentally safe, inexpensive and simple method to compare with chemical method. Use of plant in synthesis zinc oxide nanoparticles (ZnO NPs) that act as reducing and capping agent are more recommended, due to high production of product and rate of synthesis is faster than using microorganism. This study focus on the synthesis of ZnO NPs by using leaf extract of aloe vera (Aloe bardenisis miller) with different concentration (30%, 40% and 50%) and various calcination temperature which are 500 ˚C, 700 ˚C and 900 ˚C for 4 hours. Fourier – transform infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA), scanning electron microscopy (SEM), X-ray Diffraction (XRD) and Brunauer-Emmet and Teller (BET) were used to characterize the prepared samples. FTIR spectra showed present wavenumber in between 400-500 cm-1 indicated the presence of Zn-O stretch. Powder XRD pattern confirmed the hexagonal wurtzite structure with average particles size from 24.19 nm to 67.69 nm for all concentration and temperature by using Scherer’s equation. For SEM analysis the images show irregular shape for concentrations 30% and 50% with size range from 500 nm to 900 nm while for concentration 40% cubic shape was observe with size range from 140 nm to 900 nm. All characterize show that formation of ZnO NPs depend on the concentration and calcination temperature. Sample 30% and 50% ZnO NPs was applied in lithium battery at voltage from 0.01 to 3. 1.2 mAhg-1 was recorded for sample 30% ZnO NPs while 100 mAhg-1.

Matched MeSH terms: Zinc; Zinc Oxide
Fulltext Green chemistry synthesis of nanostructured zinc oxide powder using azadirachta indica extract for latent fingermark development

Revathi Rajan, Yusmazura Zakaria, Shaharum Shamsuddin, Nik Fakhuruddin Nik Hassan

Malaysian Journal of Medicine and Health Sciences, 2020;16(101):38-42.
MyJurnal

Introduction: Application of nano-engineered fingerprint dusting powders has been a recent trend to achieve latent fingermark development with superior ridge clarity. As such, efforts have been made to utilise natural resources to increase the sustainability of these emerging nano-engineered powders. Lithium-doped zinc oxide, primarily used as white pigments, have been previously applied to latent fingermarks with success. In the current study, nanostruc- tured zinc oxide, synthesised using neem extract as the reducing agent, was evaluated for fingermark development on non-porous surfaces. Methods: The reduction of zinc nitrate hexahydrate was facilitated by neem extract, pre- pared by boiling neem leaves in distilled water. The thick yellow paste recovered was calcined in the furnace to produce a light yellow powder. Physicochemical composition of the powder was determined using microscopic and spectroscopic instruments. The effectiveness of the powder was tested on natural fingermark deposited on several non-porous surfaces. Results: Nanostructured zinc oxide with particle size ranging in between 1 to 3 µm consisting of highly aggregated spherical particle with less than 100 nm dimensions were synthesised. Developed fingermarks revealed excellent ridge details and contrast on dark coloured surfaces. Studying the fingermark closely under scan- ning electron microscope displayed selective distribution of particle on the ridges of the fingermark residue and very minimal deposition on the fingermark valleys. Conclusion: Nanostructured zinc oxide fabricated using green chem- istry approach can be applied for the development of fingermark. Nevertheless, future works can be undertaken to enhance particle dispersity and to confer strong photoluminescence to the zinc oxide nanoparticles.

Matched MeSH terms: Zinc Oxide; Zinc Compounds
Fulltext Floating ZnO QDs-Modified TiO2/LLDPE Hybrid Polymer Film for the Effective Photodegradation of Tetracycline under Fluorescent Light Irradiation: Synthesis and Characterisation

Iqbal A, Saidu U, Adam F, Sreekantan S, Yahaya N, Ahmad MN, et al.

Molecules, 2021 Apr 25;26(9).
PMID: 33923041 DOI: 10.3390/molecules26092509

In this work, mesoporous TiO2-modified ZnO quantum dots (QDs) were immobilised on a linear low-density polyethylene (LLDPE) polymer using a solution casting method for the photodegradation of tetracycline (TC) antibiotics under fluorescent light irradiation. Various spectroscopic and microscopic techniques were used to investigate the physicochemical properties of the floating hybrid polymer film catalyst (8%-ZT@LLDPE). The highest removal (89.5%) of TC (40 mg/L) was achieved within 90 min at pH 9 due to enhanced water uptake by the LDDPE film and the surface roughness of the hybrid film. The formation of heterojunctions increased the separation of photogenerated electron-hole pairs. The QDs size-dependent quantum confinement effect leads to the displacement of the conduction band potential of ZnO QDs to more negative energy values than TiO2. The displacement generates more reactive species with higher oxidation ability. The highly stable film photocatalyst can be separated easily and can be repeatedly used up to 8 cycles without significant loss in the photocatalytic ability. The scavenging test indicates that the main species responsible for the photodegradation was O2●-. The proposed photodegradation mechanism of TC was demonstrated in further detail based on the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS).

Matched MeSH terms: Zinc Oxide/chemistry
Fulltext SOLAR PHOTOCATALYTIC EFFICIENCY OF ZINC OXIDE FOR WATER DECONTAMINATION

FARAH EILYANA MOHAMED

UMT Journal of Undergraduate Research, 2019;1(1):92-102.
MyJurnal

Solar photocatalysis is a green technology that takes advantage of sustainable solar energy for enhancing oxidation process of numerous harmful water contaminants. In this study, a custom solar driven zinc oxide (ZnO)-mediated photocatalytic system was developed and its efficiency to remove organic contaminants as well as to disinfect selected bacteria was investigated. Methylene blue (MB) dye was used as the model organic contaminant, while Escherichia coli(E.coli) was used as the model fecal coliform bacteria in contaminated water. A series of photodegradation experiments were conducted on water contaminated with either 10 mg/L of MB or ~1010CFU/ml of E.coli. The experiments were completed under sunlight irradiation in the presence of 1 g/L of nano ZnO photocatalyst for up to 6 hours. Using a solar thermal collector, the photoreactor operated in the temperature range of 25 to 50 oC. The findings revealed that the combination of solar thermal with solar photocatalysis usingZnO intensified the degradation of MB and disinfection of E.coli. 98.08% of MB dye and 99.99% of E.coliwere successfully removed from the water within the first 3 hours of treatment. Almost complete removal was eventually achieved after 6 hours of treatment. It is therefore suggested that ZnO-based solar photocatalytic system developed in this study is highly efficient at enhancing water decontamination process.

Matched MeSH terms: Zinc; Zinc Oxide
Fulltext Effect of ZnO on the physical properties and optical band gap of soda lime silicate glass

Zaid MH, Matori KA, Aziz SH, Zakaria A, Ghazali MS

Int J Mol Sci, 2012;13(6):7550-8.
PMID: 22837711 DOI: 10.3390/ijms13067550

This manuscript reports on the physical properties and optical band gap of five samples of soda lime silicate (SLS) glass combined with zinc oxide (ZnO) that were prepared by a melting and quenching process. To understand the role of ZnO in this glass structure, the density, molar volume and optical band gaps were investigated. The density and absorption spectra in the Ultra-Violet-Visible (UV-Visible) region were recorded at room temperature. The results show that the densities of the glass samples increased as the ZnO weight percentage increased. The molar volume of the glasses shows the same trend as the density: the molar volume increased as the ZnO content increased. The optical band gaps were calculated from the absorption edge, and it was found that the optical band gap decreased from 3.20 to 2.32 eV as the ZnO concentration increased.

Matched MeSH terms: Zinc Oxide/chemistry*

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