MyMedR

Displaying publications 21 - 40 of 50 in total

Abstract:

Sort:

Amalgamation of N-graphene quantum dots with nanocubic like TiO2: an insight study of sunlight sensitive photocatalysis

Lim PF, Leong KH, Sim LC, Abd Aziz A, Saravanan P

Environ Sci Pollut Res Int, 2019 Feb;26(4):3455-3464.
PMID: 30515688 DOI: 10.1007/s11356-018-3821-1

In this work, a sunlight-sensitive photocatalyst of nanocubic-like titanium dioxide (TiO2) and N-doped graphene quantum dots (N-GQDs) is developed through a simple hydrothermal and physical mixing method. The successful amalgamation composite photocatalyst characteristics were comprehensively scrutinized through various physical and chemical analyses. A complete removal of bisphenol A (BPA) is attained by a synthesized composite after 30 min of sunlight irradiation as compared to pure TiO2. This clearly proved the unique contribution of N-GQDs that enhanced the ability of light harvesting especially under visible light and near-infrared region. This superior characteristic enables it to maximize the absorbance in the entire solar spectrum. However, the increase of N-GQDs weight percentage has created massive oxygen vacancies that suppress the generation of active radicals. This resulted in a longer duration for a complete removal of BPA as compared to lower weight percentage of N-GQDs. Hence, this finding can offer a new insight in developing effective sunlight-sensitive photocatalysts for various complex organic pollutants degradation.

Matched MeSH terms: Photochemical Processes
Effects of oil substrate supplementation on production of prodigiosin by Serratia nematodiphila for dye-sensitized solar cell

Abdul Manas NH, Chong LY, Tesfamariam YM, Zulkharnain A, Mahmud H, Abang Mahmod DS, et al.

J Biotechnol, 2020 Jun 20;317:16-26.
PMID: 32348830 DOI: 10.1016/j.jbiotec.2020.04.011

Bacterial pigments are potential substitute of chemical photosensitizer for dye-sensitized solar cell (DSSC) due to its non-toxic property and cost-effective production from microbial fermentation. Serratia nematodiphila YO1 was isolated from waterfall in Malaysia and identified using 16S ribosomal RNA. Characterization of the red pigment produced by the bacteria has confirmed the pigment as prodigiosin. Prodigiosin was produced from the fermentation of the bacteria in the presence of different oil substrates. Palm oil exhibited the best performance of cell growth and equivalent prodigiosin yield compared to olive oil and peanut oil. Prodigiosin produced with palm oil supplementation was 93 mg/l compared to 7.8 mg/l produced without supplementation, which recorded 11.9 times improvement. Specific growth rate of the cells improved 1.4 times when palm oil was supplemented in the medium. The prodigiosin pigment produced showed comparable performance as a DSSC sensitizer by displaying an open circuit voltage of 336.1 mV and a maximum short circuit current of 0.098 mV/cm2. This study stands a novelty in proving that the production of prodigiosin is favorable in the presence of palm oil substrate with high saturated fat content, which has not been studied before. This is also among the first bacterial prodigiosin tested as photosensitizer for DSSC application.

Matched MeSH terms: Photochemical Processes
Response surface methodology analysis of the photocatalytic removal of Methylene Blue using bismuth vanadate prepared via polyol route

Abdullah AH, Moey HJ, Yusof NA

J Environ Sci (China), 2012;24(9):1694-701.
PMID: 23520879

Visible-light driven photocatalyst bismuth vanadate (BiVO4) photocatalyst was synthesized by the polyol route using ethylene glycol. The precipitate was washed, dried and calcined at 450 degrees C for 3 hr. The sample was characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), zeta potential, surface area (BET method) and band gap energy via diffuse reflectance spectroscopy (DRS). The synthesized BiVO4 has a monoclinic phase with a surface area of 4.3 m2/g and a band gap energy of 2.46 eV. A majority of the particles were in the range of 90-130 nm as obtained from the particle size distribution histrogram. The efficiency of the sample as a visible-light driven photocatalyst was examined by photodegrading Methylene Blue (MB). The effects of some operational photodegradation parameters such as mass loading, initial dye concentration and pH were also examined. Experimental design methodology was applied by response surface modeling and optimization of the removal of MB. The multivariate experimental design was employed to develop a quadratic model as a functional relationship between the percentage removal of MB and three experimental factors (BiVO4 loading, MB initial concentration and pH). The percentage removal of MB approached 67.21% under optimized conditions. In addition, a satisfactory goodness-of-fit was achieved between the,predictive and the experimental results.

Matched MeSH terms: Photochemical Processes
Photocatalytic performance of novel samarium-doped spherical-like ZnO hierarchical nanostructures under visible light irradiation for 2,4-dichlorophenol degradation

Sin JC, Lam SM, Lee KT, Mohamed AR

J Colloid Interface Sci, 2013 Jul 1;401:40-9.
PMID: 23618322 DOI: 10.1016/j.jcis.2013.03.043

A novel samarium-doped spherical-like ZnO hierarchical nanostructure (Sm/ZnO) was synthesized via a facile and surfactant-free chemical solution route. The as-synthesized products were characterized by X-ray diffraction, Brunauer-Emmett-Teller surface area analysis, field emission scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy, UV-visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The results revealed that Sm ion was successfully doped into ZnO. It was also observed that the Sm doping increased the visible light absorption ability of Sm/ZnO and a red shift for Sm/ZnO appeared when compared to pure ZnO. The photocatalytic studies revealed that the Sm/ZnO exhibited excellent photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) compared with the pure ZnO and commercial TiO2 under visible light irradiation. The photocatalytic enhancement of Sm/ZnO products was attributed to their high charge separation efficiency and ·OH generation ability as evidenced by the photoluminescence spectra. The photocatalytic investigation also showed that various parameters exerted their individual influence on the degradation rate of 2,4-DCP. By using a certain of radical scavengers, ·OH was determined to play a pivotal role for the 2,4-DCP degradation. Moreover, the Sm/ZnO could be easily separated and reused, indicating great potential for practical applications in environmental cleanup.

Matched MeSH terms: Photochemical Processes
A review on the formation of titania nanotube photocatalysts by hydrothermal treatment

Wong CL, Tan YN, Mohamed AR

J Environ Manage, 2011 Jul;92(7):1669-80.
PMID: 21450395 DOI: 10.1016/j.jenvman.2011.03.006

Titania nanotubes are gaining prominence in photocatalysis, owing to their excellent physical and chemical properties such as high surface area, excellent photocatalytic activity, and widespread availability. They are easily produced by a simple and effective hydrothermal method under mild temperature and pressure conditions. This paper reviews and analyzes the mechanism of titania nanotube formation by hydrothermal treatment. It further examines the parameters that affect the formation of titania nanotubes, such as starting material, sonication pretreatment, hydrothermal temperature, washing process, and calcination process. Finally, the effects of the presence of dopants on the formation of titania nanotubes are analyzed.

Matched MeSH terms: Photochemical Processes
One-pot synthesis of carbon dots using two different acids and their respective unique photoluminescence property

Loi E, Ng RW, Chang MM, Fong JF, Ng YH, Ng SM

Luminescence, 2017 Feb;32(1):114-118.
PMID: 27166514 DOI: 10.1002/bio.3157

Carbon dots, a new class of nanomaterial with unique optical property and have great potential in various applications. This work demonstrated the possibility of tuning the emission wavelength of carbon dots by simply changing the acid type used during synthesis. In particular, sulfuric and phosphoric acids and a mixture of the two were used to carbonize the same starting precursor, sucrose. This resulted in the isolation of carbon dots with blue (440 nm) and green (515 nm) emission. Interestingly, the use of an acid mixture at various ratios did not shift the initial emission profile, but did obviously alter the fluorescence efficiency of the peaks. This clearly showed that acid type can be used as an alternative tool to produce carbon dots that have different emissions using the same starting precursor. Copyright © 2016 John Wiley & Sons, Ltd.

Matched MeSH terms: Photochemical Processes
Enhanced photocatalytic regeneration of carboxymethyl cellulose/lignin/ZnO complex hydrogel after methylene blue adsorption

Fu J, Yap JX, Leo CP, Chang CK

Int J Biol Macromol, 2024 Aug;274(Pt 2):133510.
PMID: 38960270 DOI: 10.1016/j.ijbiomac.2024.133510

The biodegradable, nontoxic, and renewable carboxymethyl cellulose (CMC) hydrogel has been developed into a green adsorbent. However, the weak chemical interaction limits its adsorption capability and reusability. This work incorporated lignin with complex structure and ZnO nanoparticles with photocatalytic properties into CMC hydrogel beads to improve the removal of methylene blue (MB) through chemical interaction. Scanning electron microscopic images and Fourier-transform infrared spectra confirmed the compatibility between lignin and ZnO nanoparticles as well as the increment of active sites for dye removal. The MB adsorption on CMC hydrogel beads was more significantly affected by the temperate and initial concentration compared to contact time, pH, and adsorbent dosage. The MB adsorption capacity of CMC hydrogel was improved to 276.79 mg/g after incorporating lignin and ZnO nanoparticles. The adsorption followed the pseudo-second-order kinetic model and Langmuir isotherm model, indicating chemical adsorption. After 6 cycles, the adsorption capacity was reduced by about 15 %. The UV irradiation could recover and improve MB adsorption capacity of CMC hydrogel beads containing ZnO nanoparticles due to the introduction of reactive oxygen species.

Matched MeSH terms: Photochemical Processes
Revolutionizing photocatalysis: Synthesis of innovative poly(N-tertiary-butylacrylamide)-graft-hydroxypropyl cellulose polymers for thermo-responsive applications via metal-free organic photoredox catalysis

Iqbal MA, Younis MW, Maqbool M, Goh HH, Kurniawan TA, Amjad M, et al.

Int J Biol Macromol, 2025 Feb;288:138775.
PMID: 39675599 DOI: 10.1016/j.ijbiomac.2024.138775

In this study, we present a groundbreaking approach utilizing metal-free, visible light-mediated organic photoredox catalyzed atom transfer radical polymerization (O-ATRP) to synthesize cellulose-based stimuli-responsive polymers. Our method resulted in the successful synthesis of innovative metal-free poly(N-tertiary-butylacrylamide)-graft-hydroxypropyl cellulose (PNTBAM-g-HPC) polymers with exceptional control over molecular weight and narrow dispersity index (Đ) and explored their applications in organo-photocatalytic reactions. This approach addresses the limitations of traditional atom transfer radical polymerization method, which suffer from metal contamination and toxicity related problems. O-ATRP and organic photoredox catalysts have been sought to address these difficult challenges. In this study, we synthesized organic compound; 2,4,5,6-tetrakis(diphenylamino)isophthalonitrile (4DPIPN), which served as an organic photoredox catalyst, enabling the synthesis and application study of PNTBAM-g-HPC polymers via organic photoredox catalysis. Furthermore, by employing 4DPIPN, three different types of PNTBAM-g-HPC polymers were synthesized. Through thorough characterization techniques including FTIR, NMR, UV/Visible spectroscopy, TGA, and GPC analysis, we confirmed the successful synthesis of photocatalyst and three different types of PNTBAM-g-HPC polymers under O-ATRP conditions. By adjusting the molar ratios of PNTBAM side chains, we fine-tuned the LCST of HTA-20 polymers to 37.3 °C, demonstrating their thermoresponsive behavior. This synthetic approach shows great potential for applications in biosensors, pharmaceuticals, biomedical engineering, and drug delivery systems.

Matched MeSH terms: Photochemical Processes
Unveiling the green synthesis of WO3 nanoparticles by using beetroot (Beta vulgaris) extract for photocatalytic oxidation of rhodamine B

Anggraini F, Fatimah I, Ramanda GD, Nurlaela N, Wijayanti HK, Sagadevan S, et al.

Chemosphere, 2025 Feb;370:143890.
PMID: 39653190 DOI: 10.1016/j.chemosphere.2024.143890

Tungsten oxide (WO3) nanoparticles (WO3NPs) were prepared using beetroot (Beta vulgaris) extract. The synthesis was optimized by evaluating the effect of pH during the reduction of the WO3 precursor and sintering temperature. Physicochemical characterization of the formed nanoparticles was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance UV-visible spectroscopy. Furthermore, the prepared WO3NPs were employed as photocatalyst for rhodamine B removal over the photocatalytic oxidation mechanism. Synthesis optimization revealed that a single phase of WO3NPs obtained by reduction at pH 4 and a sintering temperature of 550 °C. XRD and XPS measurements revealed that the single-phase WO3NPs was obtained with a crystallite size of 26.4 nm. SEM and transmission electron microscopy (TEM) indicated polymorphic forms, predominantly as nanorods, with a mean particle size of 24 nm. The WO3NPs have a band gap energy of 2.9 eV, supporting their performance as a photocatalyst. Evaluation of the photocatalytic activities of WO3NPs represents high activity and reusability of the material. A removal efficiency of 99.67% was achieved during 30 min of treatment under UV light illumination. A study on the effect of scavengers revealed the important role of hydroxy radicals in the photocatalysis mechanism. WO3NPs can be recycled and reused for photocatalysis, maintaining photoactivity for five cycles.

Matched MeSH terms: Photochemical Processes
A highly efficient immobilized ZnO/Zn photoanode for degradation of azo dye Reactive Green 19 in a photocatalytic fuel cell

Lee SL, Ho LN, Ong SA, Wong YS, Voon CH, Khalik WF, et al.

Chemosphere, 2017 Jan;166:118-125.
PMID: 27693872 DOI: 10.1016/j.chemosphere.2016.09.082

Photocatalytic fuel cell (PFC) is a potential wastewater treatment technology that can generate electricity from the conversion of chemical energy of organic pollutants. An immobilized ZnO/Zn fabricated by sonication and heat attachment method was applied as the photoanode and Pt/C plate was used as the cathode of the PFC in this study. Factors that affect the decolorization efficiency and electricity generation of the PFC such as different initial dye concentrations and pH were investigated. Results revealed that the degradation of Reactive Green 19 (RG19) was enhanced in a closed circuit PFC compared with that of a opened circuit PFC. Almost 100% decolorization could be achieved in 8 h when 250 mL of 30 mg L(-1) of RG19 was treated in a PFC without any supporting electrolyte. The highest short circuit current of 0.0427 mA cm(-2) and maximum power density of 0.0102 mW cm(-2) was obtained by PFC using 30 mg L(-1) of RG19. The correlation between dye degradation, conductivity and voltage output were also investigated and discussed.

Matched MeSH terms: Photochemical Processes*
Fulltext Fabrication and characterization of gelatin stabilized silver nanoparticles under UV-light

Darroudi M, Ahmad MB, Zak AK, Zamiri R, Hakimi M

Int J Mol Sci, 2011;12(9):6346-56.
PMID: 22016663 DOI: 10.3390/ijms12096346

Silver nanoparticles (Ag-NPs) were successfully synthesized using the UV irradiation of aqueous solutions containing AgNO(3) and gelatin as a silver source and stabilizer, respectively. The UV irradiation times influence the particles' diameter of the Ag-NPs, as evidenced from surface plasmon resonance (SPR) bands and transmission electron microscopy (TEM) images. When the UV irradiation time was increased, the mean size of particles continuously decreased as a result of photoinduced Ag-NPs fragmentation. Based on X-ray diffraction (XRD), the UV-irradiated Ag-NPs were a face-centered cubic (fcc) single crystal without any impurity. This study reveals that the UV irradiation-mediated method is a green chemistry and promising route for the synthesis of stable Ag-NPs for several applications (e.g., medical and surgical devices). The important advantages of this method are that it is cheap, easy, and free of toxic materials.

Matched MeSH terms: Photochemical Processes/radiation effects
Photo-oxidative degradation of motorcycle helmets in Hanoi, Vietnam: A prospective preliminary study

Ramli R, Che Man Z, Nordin R, Abdul Karim F, Rashdi MF, Oxley J, et al.

Traffic Inj Prev, 2016 Sep;17 Suppl 1:79-85.
PMID: 27586107 DOI: 10.1080/15389588.2016.1203428

OBJECTIVE: Vietnamese spend hours travelling on the road using their motorcycles. Their helmets are exposed continuously to sunlight and rain. The objectives of this study were to determine the association between the effect of photo-oxidative degradation (POD) of the outer shells and helmet age on helmet damage. The micro-structural change of the outer shell was also investigated.
METHODS: This was a prospective, cross sectional study recruiting injured motorcyclists from Hanoi, Vietnam hospital. The participants were interviewed by a trained researcher. The participants' helmets were collected post-crash. Initially, the helmets were examined for their type and external characteristics. A 3 cm × 3 cm cut was made on the helmet in the impacted and non-impacted areas (control). These areas were investigated for evidence of POD and presence of micro-cracks and material disintegration. 50 participants were enrolled. Sources of information included questionnaire and laboratory analyses. The helmet factors of interest were age of the helmet, exposure of helmet to sunlight and rain (duration/day) and history of previous impact. Laboratory analyses included Fourier Transform Infra Red (FTIR) for degradation and scanning electron microscopy (SEM) for micro-structural examination.
RESULTS: Majority of the helmets was the open-face type, 40 (80.0%). 31 (62.0%) helmets aged less than three years (LTY) and 19 (38.0%) were three years old or more (MTY). 19 (61.3%) of the LTY helmets and 12 (63.2%) MTY helmets showed evidence of POD. The duration of helmet exposure to sunlight was between 93 to 6570 hours (mean 2347.74 hours; SD 1733.39). The SEM showed 15 helmets (30%) with micro-fractures, 21 helmets (42.0%) with material disintegration. Prolonged uv exposure to the ABS helmets resulted in changes in the helmet material in the form of material disintegration and microcracks and this association was statistically significant (p = 0.03).
CONCLUSION: POD occurs due to routine exposure to the ultraviolet light. Prolonged uv exposure affects outer shell surface material integrity.

Matched MeSH terms: Photochemical Processes*
Spatial-temporal variations in surface ozone over Ushuaia and the Antarctic region: observations from in situ measurements, satellite data, and global models

Nadzir MSM, Ashfold MJ, Khan MF, Robinson AD, Bolas C, Latif MT, et al.

Environ Sci Pollut Res Int, 2018 Jan;25(3):2194-2210.
PMID: 29116536 DOI: 10.1007/s11356-017-0521-1

The Antarctic continent is known to be an unpopulated region due to its extreme weather and climate conditions. However, the air quality over this continent can be affected by long-lived anthropogenic pollutants from the mainland. The Argentinian region of Ushuaia is often the main source area of accumulated hazardous gases over the Antarctic Peninsula. The main objective of this study is to report the first in situ observations yet known of surface ozone (O3) over Ushuaia, the Drake Passage, and Coastal Antarctic Peninsula (CAP) on board the RV Australis during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC'16). Hourly O3 data was measured continuously for 23 days using an EcoTech O3 analyzer. To understand more about the distribution of surface O3 over the Antarctic, we present the spatial and temporal of surface O3 of long-term data (2009-2015) obtained online from the World Meteorology Organization of World Data Centre for greenhouse gases (WMO WDCGG). Furthermore, surface O3 satellite data from the free online NOAA-Atmospheric Infrared Sounder (AIRS) database and online data assimilation from the European Centre for Medium-Range Weather Forecasts (ECMWF)-Monitoring Atmospheric Composition and Climate (MACC) were used. The data from both online products are compared to document the data sets and to give an indication of its quality towards in situ data. Finally, we used past carbon monoxide (CO) data as a proxy of surface O3 formation over Ushuaia and the Antarctic region. Our key findings were that the surface O3 mixing ratio during MASEC'16 increased from a minimum of 5 ppb to ~ 10-13 ppb approaching the Drake Passage and the Coastal Antarctic Peninsula (CAP) region. The anthropogenic and biogenic O3 precursors from Ushuaia and the marine region influenced the mixing ratio of surface O3 over the Drake Passage and CAP region. The past data from WDCGG showed that the annual O3 cycle has a maximum during the winter of 30 to 35 ppb between June and August and a minimum during the summer (January to February) of 10 to 20 ppb. The surface O3 mixing ratio during the summer was controlled by photochemical processes in the presence of sunlight, leading to the depletion process. During the winter, the photochemical production of surface O3 was more dominant. The NOAA-AIRS and ECMWF-MACC analysis agreed well with the MASEC'16 data but twice were higher during the expedition period. Finally, the CO past data showed the surface O3 mixing ratio was influenced by the CO mixing ratio over both the Ushuaia and Antarctic regions. Peak surface O3 and CO hourly mixing ratios reached up to ~ 38 ppb (O3) and ~ 500 ppb (CO) over Ushuaia. High CO over Ushuaia led to the depletion process of surface O3 over the region. Monthly CO mixing ratio over Antarctic (South Pole) were low, leading to the production of surface O3 over the Antarctic region.

Matched MeSH terms: Photochemical Processes
Fulltext Novel preparation of highly photocatalytically active copper chromite nanostructured material via a simple hydrothermal route

Beshkar F, Zinatloo-Ajabshir S, Bagheri S, Salavati-Niasari M

PLoS One, 2017;12(6):e0158549.
PMID: 28582420 DOI: 10.1371/journal.pone.0158549

Highly photocatalytically active copper chromite nanostructured material were prepared via a novel simple hydrothermal reaction between [Cu(en)2(H2O)2]Cl2 and [Cr(en)3]Cl3.3H2O at low temperature, without adding any pH regulator or external capping agent. The as-synthesized nanostructured copper chromite was analyzed by transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy, energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Results of the morphological investigation of the as-synthesized products illustrate that the shape and size of the copper chromite depended on the surfactant sort, reaction duration and temperature. Moreover, the photocatalytic behavior of as-obtained copper chromite was evaluated by photodegradation of acid blue 92 (anionic dye) as water pollutant.

Matched MeSH terms: Photochemical Processes
Elucidating the effects of different photoanode materials on electricity generation and dye degradation in a sustainable hybrid system of photocatalytic fuel cell and peroxi-coagulation process

Nordin N, Ho LN, Ong SA, Ibrahim AH, Lee SL, Ong YP

Chemosphere, 2019 Jan;214:614-622.
PMID: 30292044 DOI: 10.1016/j.chemosphere.2018.09.144

The hybrid system of photocatalytic fuel cell - peroxi-coagulation (PFC-PC) is a sustainable and green technology to degrade organic pollutants and generate electricity simultaneously. In this study, three different types of photocatalysts: TiO2, ZnO and α-Fe2O3 were immobilized respectively on carbon cloth (CC), and applied as photoanodes in the photocatalytic fuel cell of this hybrid system. Photocatalytic fuel cell was employed to drive a peroxi-coagulation process by generating the external voltage accompanying with degrading organic pollutants under UV light irradiation. The degradation efficiency of Amaranth dye and power output in the hybrid system of PFC-PC were evaluated by applying different photoanode materials fabricated in this study. In addition, the effect of light on the photocurrent of three different photoanode materials was investigated. In the absence of light, the reduction of photocurrent percentage was found to be 69.7%, 17.3% and 93.2% in TiO2/CC, ZnO/CC and α-Fe2O3/CC photoanodes, respectively. A maximum power density (1.17 mWcm-2) and degradation of dye (93.8%) at PFC reactor were achieved by using ZnO/CC as photoanode. However, the different photoanode materials at PFC showed insignificant difference in dye degradation trend in the PC reactor. Meanwhile, the degradation trend of Amaranth at PFC reactor was influenced by the recombination rate, electron mobility and band gap energy of photocatalyst among different photoanode materials.

Matched MeSH terms: Photochemical Processes
Constructing magnetic Pt-loaded BiFeO3 nanocomposite for boosted visible light photocatalytic and antibacterial activities

Jaffari ZH, Lam SM, Sin JC, Mohamed AR

Environ Sci Pollut Res Int, 2019 Apr;26(10):10204-10218.
PMID: 30758796 DOI: 10.1007/s11356-019-04503-9

Visible light-responsive Pt-loaded coral-like BiFeO3 (Pt-BFO) nanocomposite at different Pt loadings was synthesized via a two-step hydrothermal synthesis method. The as-synthesized photocatalyst was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and magnetic hysteresis loop (M-H loop) analyses. The FESEM images revealed that Pt nanoparticles were evenly distributed on the coral-like BFO. The UV-vis DRS results indicated that the addition of Pt dopant modified the optical properties of the BFO. The as-synthesized Pt-BFO nanocomposite was effectively applied for the photodegradation of malachite green (MG) dye under visible light irradiation. Specifically, 0.5 wt% Pt-BFO nanocomposite presented boosted photocatalytic performance than those of the pure BFO and commercial TiO2. Such a remarkably improved photoactivity could be mainly attributed to the formation of good interface between Pt and BFO, which not only boosted the separation efficiency of charge carriers but also possessed great redox ability for significant photocatalytic reaction. Moreover, the strong magnetic property of the Pt-BFO nanocomposite was helpful in the particle separation along with its great recyclability. The radical scavenger test indicated that hole (h+), hydroxyl (·OH) radical, and hydrogen peroxide (H2O2) were the main oxidative species for the Pt-BFO photodegradation of MG. Finally, the Pt-BFO nanocomposite was revealed high antibacterial activity towards Bacillus cereus (B. cereus) and Escherichia coli (E. coli) microorganisms, highlighting its potential photocatalytic and antibacterial properties at different industrial and biomedical applications.

Matched MeSH terms: Photochemical Processes
Hierarchically structured ternary heterojunctions based on Ce3+/ Ce4+ modified Fe3O4 nanoparticles anchored onto graphene oxide sheets as magnetic visible-light-active photocatalysts for decontamination of oxytetracycline

Hassandoost R, Pouran SR, Khataee A, Orooji Y, Joo SW

J Hazard Mater, 2019 08 15;376:200-211.
PMID: 31128399 DOI: 10.1016/j.jhazmat.2019.05.035

The main prerequisite of an active visible-light-driven photocatalyst is to effectively utilize the visible light to induce electron-hole (e-/h+) pairs of expanded lifetime. To this end, for the first time, the ternary heterojunctions of CeO2/Fe3O4 /Graphene oxide and Ce3+/ Fe3O4 /Graphene oxide (CeO2/Fe3O4/GO and Fe2.8Ce0.2O4/GO) were prepared via facile ultrasonic-assisted procedures and employed for destruction of oxytetracycline (OTC) under visible light irradiation. The changes in the relative crystal structure, morphology, atomic and surface functional group composition, magnetic, and optic properties of magnetite were uncovered by various techniques. The substantial degradation and mineralization of OTC via visible light/Fe2.8Ce0.2O4/GO system were thoroughly discussed in terms of narrowed band gap energy, the principal function of Ce3+/Ce4+ and Fe2+/Fe3+ redox pairs and GO platelets, enhanced charge separation and transfer, and enlarged active surface area. Furthermore, the performance of visible light/Fe2.8Ce0.2O4/GO system was evaluated for treating real wastewater and its efficiency was investigated using a number of enhancers and scavengers. Finally, the generated byproducts in the course of photodegradation were determined and the oxidation pathway, photocatalytic kinetics, and plausible mechanism were proposed. The results confirmed that the introduced Ce ions and graphene oxide sheets boost the photo-catalytic efficiency of magnetite for photodegradation of OTC.

Matched MeSH terms: Photochemical Processes
Fulltext Influence of Sputtering Temperature of TiO2 Deposited onto Reduced Graphene Oxide Nanosheet as Efficient Photoanodes in Dye-Sensitized Solar Cells

Low FW, Chin Hock G, Kashif M, Samsudin NA, Chau CF, Indah Utami AR, et al.

Molecules, 2020 Oct 21;25(20).
PMID: 33096759 DOI: 10.3390/molecules25204852

Renewable solar energy is the key target to reduce fossil fuel consumption, minimize global warming issues, and indirectly minimizes erratic weather patterns. Herein, the authors synthesized an ultrathin reduced graphene oxide (rGO) nanosheet with ~47 nm via an improved Hummer's method. The TiO2 was deposited by RF sputtering onto an rGO nanosheet with a variation of temperature to enhance the photogenerated electron or charge carrier mobility transport for the photoanode component. The morphology, topologies, element composition, crystallinity as well as dye-sensitized solar cells' (DSSCs) performance were determined accordingly. Based on the results, FTIR spectra revealed presence of Ti-O-C bonds in every rGO-TiO2 nanocomposite samples at 800 cm-1. Besides, XRD revealed that a broad peak of anatase TiO2 was detected at ~25.4° after incorporation with the rGO. Furthermore, it was discovered that sputtering temperature of 120 °C created a desired power conversion energy (PCE) of 7.27% based on the J-V plot. Further increase of the sputtering temperature to 160 °C and 200 °C led to excessive TiO2 growth on the rGO nanosheet, thus resulting in undesirable charge recombination formed at the photoanode in the DSSC device.

Matched MeSH terms: Photochemical Processes
Optimization of photocatalytic degradation of palm oil mill effluent in UV/ZnO system based on response surface methodology

Ng KH, Cheng YW, Khan MR, Cheng CK

J Environ Manage, 2016 Dec 15;184(Pt 3):487-493.
PMID: 27784576 DOI: 10.1016/j.jenvman.2016.10.034

This paper reports on the optimization of palm oil mill effluent (POME) degradation in a UV-activated-ZnO system based on central composite design (CCD) in response surface methodology (RSM). Three potential factors, viz. O2 flowrate (A), ZnO loading (B) and initial concentration of POME (C) were evaluated for the significance analysis using a 2(3) full factorial design before the optimization process. It is found that all the three main factors were significant, with contributions of 58.27% (A), 15.96% (B) and 13.85% (C), respectively, to the POME degradation. In addition, the interactions between the factors AB, AC and BC also have contributed 4.02%, 3.12% and 1.01% to the POME degradation. Subsequently, all the three factors were subjected to statistical central composite design (CCD) analysis. Quadratic models were developed and rigorously checked. A 3D-response surface was subsequently generated. Two successive validation experiments were carried out and the degradation achieved were 55.25 and 55.33%, contrasted with 52.45% for predicted degradation value.

Matched MeSH terms: Photochemical Processes
Fulltext Optimisation of the Photonic Efficiency of TiO2 Decorated on MWCNTs for Methylene Blue Photodegradation

Abdullahi N, Saion E, Shaari AH, Al-Hada NM, Keiteb A

PLoS One, 2015;10(5):e0125511.
PMID: 25993127 DOI: 10.1371/journal.pone.0125511

MWCNTs/TiO2 nanocomposite was prepared by oxidising MWCNT in H2SO4/HNO3 then decorating it with TiO2-p25 nanopowder. The composites were characterised using XRD, TEM, FT-IR PL and UV-vis spectroscopy. The TEM images have shown TiO2 nanoparticles immobilised onto the sidewalls of the MWCNTs. The UV-vis spectrum confirms that the nanocomposites can significantly absorb more light in the visible regions compared with the commercial TiO2 (P25). The catalytic activity of these nanocomposites was determined by photooxidation of MB aqueous solution in the presence of visible light. The MWCNTs/TiO2 (1:3) mass ratio showed maximum degradation efficiency. However, its activity was more favourable in alkaline and a neutral pH than an acidic medium.

Matched MeSH terms: Photochemical Processes

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links