scholarly journals Photodegradation of some brominated and phenolic micropollutants in raw hospital wastewater with CeO2 and TiO2 nanoparticles

2017 ◽  
Vol 76 (10) ◽  
pp. 2603-2622 ◽  
Author(s):  
Delia Teresa Sponza ◽  
Gökçe Güney
Keyword(s):  
Surface Area ◽  
Uv Light ◽  
Irradiation Time ◽  
Anatase Phase ◽  
Hospital Wastewater ◽  
Nano Tio2 ◽  
Experimental Conditions ◽  
Light Power ◽  
Sequential Treatments ◽  
Average Size

Abstract In this study, the degradations of 2,3,4,5,6-pentabromotoluene (PBT), 2,3,4,5,6-pentabromoethyl benzene (PBEB), triclosan (TCS) and gemfibrozil (GFZ) in raw hospital wastewater were investigated with cerium (IV) oxide and titanium (IV) oxide nanoparticles considering the mechanisms of adsorption, photolysis, and photocatalysis with UV-C lamps. The effects of nano-CeO2 and nano-TiO2 concentrations, irradiation times, UV light powers and hospital wastewater pH on the photodegradation yields of micropollutants namely PBT, PBEB, TCS and GFZ were investigated throughout photocatalysis. The nano-TiO2 produced had an anatase phase with crystalline shape with a surface area of 205 m2 g−1 and an average size of 11.50 nm. The CeO2 nanoparticles had a spherical shape with a higher surface area (302 m2 g−1) than that of TiO2 and a lower average size (8.11 nm). It was found that the removals of PBT, PBEB, TCS and GFZ with adsorption (5.7%–17.1%) and photolysis (9.0%–15.9%) were not significant for both nanoparticles. The photodegradation of PBT (92%), PBEB (90%), TCS (97%) and GFZ (95%) with nano-CeO2 gave better results than nano-TiO2 (90%, 87%, 94% and 93% for PBT, PBEB, TCS and GFZ, respectively) under optimum experimental conditions (0.50 g L−1 nano-CeO2, 45 min irradiation time, 25 °C temperature, pH = 8.50, 210 W UV light power). Both nanoparticles were reused effectively after photo-removals of the micropollutants from the hospital wastewater. The lowest photodegradation yields were 80%, 78%, 75% and 74% for TCS, GFZ, PBT and PBEB, respectively, with nano-TiO2 after six sequential treatments. The lowest photodegradation yields were 86%, 83%, 80% and 79% for the same micropollutants, respectively, with nano-CeO2 after six sequential treatments. The cost to treat 1 m3 raw hospital wastewater were 8.70 € and 2.28 €, for the photocatalytic treatments with nano-TiO2 and nano-CeO2, respectively.

scholarly journals Effect of Ultraviolet Light Irradiation Combined with Riboflavin on Different Bacterial Pathogens from Ocular Surface Infection

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Jing Shen ◽  
Qingfeng Liang ◽  
Guanyu Su ◽  
Yang Zhang ◽  
Zhiqun Wang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Uv Light ◽  
Irradiation Time ◽  
Survival Rates ◽  
Experimental Conditions ◽  
Light Power ◽  
Bacteria Growth ◽  
Inhibition Effect ◽  
Staphylococcus Epidermis

In order to study Staphylococcus epidermis and Staphylococcus aureus in vitro viability after the exposure to ultraviolet (UV) light and riboflavin, twelve strains of Staphylococcus epidermis and twelve strains of Staphylococcus aureus were isolated from patients with bacterial keratitis. The growth situation of Staphylococcus epidermidis and Staphylococcus aureus under different experimental conditions was qualitatively observed. The number of colonies surviving bacteria was counted under different UV light power and different exposure time. The experiment showed that there was no inhibition effect on the growth of bacteria using riboflavin alone. In UV alone group and UV-riboflavin group, inhibition effect on the bacteria growth was found. The UV-riboflavin combination had better inhibition effect on bacteria than UV irradiation alone. The amount of bacteria in the UV-riboflavin group was decreased by 99.1%~99.5% and 54.8%~64.6% in the UV alone group, when the UV light power was 10.052 mW/cm2 and the irradiation time was 30 min. Moreover, with the increase of the UV power or irradiation time, the survival rates of bacteria were rapidly reduced. Compared with Staphylococcus aureus, Staphylococcus epidermis was more easily to be killed under the action of UV light combined with riboflavin.

scholarly journals Reuse and recovery of raw hospital wastewater containing ofloxacin after photocatalytic treatment with nano graphene oxide magnetite

2017 ◽  
Vol 77 (2) ◽  
pp. 304-322 ◽  
Author(s):  
D. T. Sponza ◽  
P. Alicanoglu
Keyword(s):  
Graphene Oxide ◽  
Irradiation Time ◽  
Oxygen Demand ◽  
Pollutant Removal ◽  
Hospital Wastewater ◽  
Removal Efficiencies ◽  
Sequential Treatments ◽  
Nano Graphene ◽  
Kjeldahl Nitrogen

Abstract Inadequate treatment of hospital wastewater could result in considerable risks to public health due to its macro- and micropollutant content. In order to eliminate this problem, a new nanoparticle composite was produced under laboratory conditions and a photocatalytic degradation approach was used. Chemical oxygen demand (COD), biological oxygen demand (BOD5), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorus (TP) (macro) and oflaxin (micro) pollutant removal were investigated with the nano graphene oxide magnetite (Nano-GO/M) particles by two different processes, namely adsorption and photodegradation. Low removal efficiencies (21–60%) were obtained in the adsorption process for the parameters given above, after 90 min contact time at a pH of 7.8 with 5 g/L Nano-GO/M composite. Using the photodegradation process, higher removal efficiencies were obtained with 2 g/L Nano-GO/M composite for COD (88%), TSS (82%), TKN (95%) and oflaxin (97%), at pH 7.8 after 60 min irradiation time at a UV power of 300 W. The synthesized nanoparticle was reused for two sequential treatments of pharmaceutical wastewater with no significant losses of removal efficiencies (for oflaxin 97%–90%). The quality of the treated hospital wastewater was first class according to the Turkish Water Pollution Control Regulations criteria. This water could also be used for irrigation purposes.

Preparation and Characterization of Activated Carbon Fiber Supported Nano-TiO2

2012 ◽  
Vol 503-504 ◽  
pp. 646-649
Author(s):  
Xiao Ling Guo ◽  
Xiang Dong Wang ◽  
De Ping Ben
Keyword(s):  
Activated Carbon ◽  
Carbon Fiber ◽  
Surface Area ◽  
Anatase Phase ◽  
Sol Gel ◽  
Activated Carbon Fiber ◽  
Bet Surface Area ◽  
Tetrabutyl Titanate ◽  
Nano Tio2 ◽  
Mean Size

Nano-TiO2 powders were synthesized by a sol-gel method using tetrabutyl titanate as the precursor, and then the composites of ACF(activated carbon fiber) supported nano-TiO2 was prepared by impregnating method. Tests of the amount of loaded TiO2 showed that three impregnating times was adequate. The Nano-TiO2 powders and composites were characterized by XRD, SEM, and BET surface area method. XRD tests showed that nano-TiO2 powders prepared by this way are anatase phase, and the mean size of the particles is about 11.5nm, when the calcination temperature is 673K. BET results showed that compared with original ACF, the surface area of the composites decreased slightly, indicating the impregnating process did not change the porous structure of original ACF. SEM result indicated that most of the nano-TiO2 particles as the size of 10-20nm were homogeneously dispersed on the surface of ACF.

scholarly journals Synthesis and characterization of gold nanoparticles on titanium dioxide for the catalytic photodegradation of 2,4-dichlorophenoxyacetic acid

2018 ◽  
Vol 16 (5) ◽  
Author(s):  
E. Romero Torres ◽  
M. Gutiérrez Arzaluz ◽  
V Mugica Alvarez ◽  
L. González Reyes ◽  
M. Torres Rodríguez ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Titanium Dioxide ◽  
Uv Light ◽  
Anatase Phase ◽  
Precipitation Method ◽  
Dichlorophenoxyacetic Acid ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Average Size ◽  
2,4 Dichlorophenoxyacetic Acid

The photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) using a Au/TiO2 catalyst and ultraviolet (UV) light energy source (9 mW/cm2) discussed. Gold nanoparticles were synthesized by controlled urea reduction and deposited on titanium dioxide (TiO2) by the deposition-precipitation method. The average size of the nanoparticles was 6-8 nm. X-ray diffraction (XRD) characterization confirmed that TiO2 was present in the anatase phase, whereas the presence and particle size of gold were determined by transmission electron microscopy (TEM). The results of the degradation showed that the activity of TiO2 was improved when Au nanoparticles were present on the surface. The reactions were performed at atmospheric pressure and room temperature.

scholarly journals TiO2 Microwave Synthesis, Electrophoretic Deposition of Thin Film, and Photocatalytic Properties for Methylene Blue and Methyl Red Dyes

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
A. K. Singh ◽  
Umesh T. Nakate
Keyword(s):  
Thin Film ◽  
Methylene Blue ◽  
Surface Area ◽  
Electrophoretic Deposition ◽  
Uv Light ◽  
Steel Substrate ◽  
Low Cost ◽  
Anatase Phase ◽  
Energy Dispersive Spectrometer ◽  
Methyl Red

Electrophoretic deposition (EPD) of TiO2 thin film was carried out at room temperature on low cost steel substrate using microwave synthesized nanoparticles (NPs) of TiO2. Synthesized NPs and EPD thin film were characterized at different stages of synthesis for its crystal structure, morphology, elemental analysis, and surface area. Spherical particle morphology and formation of TiO2 were confirmed by scanning electron micrograph (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). Synthesized NPs were formed in anatase phase having crystallite size of about 12.3 nm from Scherrer's formula using full width half maxima (FWHM). Surface area was found to be 43.52 m2/g by BET giving particle size of 33 nm. Photocatalytic (PC) behavior of TiO2 NPs and EPD TiO2 film on steel substrate was investigated under UV light for two commercial dyes and their photocatalysis efficiency was analyzed. NPs have shown better efficiency for methylene blue (MB) dye than EPD film whereas EPD film have shown higher PC activity for methyl red (MR) dye.

Effect of Heat Treatment on the Micro-Structural, Crystallinity and Photocatalytic Properties of Hydrothermally Prepared Titanate Nanowires

2016 ◽  
Vol 1133 ◽  
pp. 13-17
Author(s):  
Mohamad Siti Mariam ◽  
A.B. Siti Najihah ◽  
A.Z. Zuhana ◽  
M. Abd Kadir
Keyword(s):  
Aqueous Solution ◽  
Uv Light ◽  
Irradiation Time ◽  
Anatase Phase ◽  
Hydrothermal Process ◽  
Sodium Titanate ◽  
Xrd Analysis ◽  
Sample Heat ◽  
Heat Treated ◽  
Titanate Nanowires

Titanate nanowires were synthesised by hydrothermal process in 10M NaOH aqueous solution at 200oC for 24h. The samples were washed repeatedly in HCl aq. solution and deionized water until pH ~7. Subsequently, the samples were heat-treated at 400-850°C in air for 2h. The X-ray diffraction (XRD) analysis of the sample heat-treated at 800°C showed the crystalline structure of sodium titanate (Na2Ti6O13 ), while the presence of anatase phase was detected from the sample heat-treated at 850°C. Wire-like morphology of the synthesized sample was observed using FE-SEM. The photocatalytic activity of the samples heat-treated at 600,800, 850°C and 900°C was investigated by measuring the degradation of methylene blue (MB) in aqueous solution under UV-light irradiation and more than 90% of the dye was efficiently degraded by the sample heat-treated at 850°C within 45 minutes irradiation time as compared to other tested samples.

scholarly journals Degradation of Phenol by Photocatalysis Using TiO2/Montmorillonite Composites Under UV Light

2021 ◽  
Author(s):  
Huijuan Li ◽  
Yeting Yao ◽  
Xiaoyan Yang ◽  
Xusheng Zhou ◽  
Ran Lei ◽  
...  
Keyword(s):  
High Performance ◽  
Ph Value ◽  
Uv Light ◽  
Irradiation Time ◽  
Phenol Degradation ◽  
Influential Factors ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
Transmission Electron ◽  
Average Size

Abstract Composites of Titanium (IV) oxide combined with montmorillonite (MMT) with various TiO2/MMT were prepared for photocatalysis application. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance UV–visible spectroscopy. The main influential factors such as the TiO2/MMT dose, calcined temperature and pH value of the solution were studied. The main intermediates of phenol degradation were determined by High Performance Liquid Chromatography (HPLC). The results showed that the average size of TiO2 nanoparticles was decreased from 22.51 nm to 10.66 nm through the immobilization on MMT. The components in the interlayer domain were replaced by titanium pillars, and the pillaring reaction proceeded in the interlayer domain, and the basic skeleton of MMT was unchanged, and also TiO2 was dispersed on the surface of the MMT. When the initial concentration of phenol is 10 mg/L, the phenol solution pH is 6 and the UV light irradiation time is 240 min, the phenol degradation rate of 30%TiO2/MMT composite is 89.8%, which is better than MMT (11.5%) and pure TiO2 (58.8%). It shows that TiO2 loaded on MMT improves its photocatalytic activity. The phenol reaction process detected by HPLC showed that it had undergone through hydroquinone and benzoquinone, and finally converted into maleic acid and carbon dioxide and small molecules. The possible photocatalysis mechanism is presented.

Facile synthesis of TiO2-RGO composite with enhanced performance for the photocatalytic mineralization of organic pollutants

2016 ◽  
Vol 73 (8) ◽  
pp. 1927-1936 ◽  
Author(s):  
Roshan K. Nainani ◽  
Pragati Thakur
Keyword(s):  
Methylene Blue ◽  
Graphene Oxide ◽  
Surface Area ◽  
Diffuse Reflectance Spectroscopy ◽  
Uv Light ◽  
Anatase Phase ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Uniform Dispersion ◽  
Redox Method

Current research reports the synthesis of reduced graphene oxide (RGO)-TiO2 nanocomposite by in-situ redox method and graphene oxide by modified hummers method. The ratio of RGO and TiO2 in the composite was optimized to show best photocatalytic activity for the degradation of targeted pollutants. Optimized (1:10) RGO-TiO2 nanocomposite was characterized by various techniques viz. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller surface area (BET), Raman and diffuse reflectance spectroscopy (DRS) technique confirming successful formation of nanocomposite. XRD results confirm the presence of anatase phase in RGO-TiO2. Uniform dispersion of TiO2 nanoparticles on RGO could be seen from TEM images. The obtained results of (1:10) RGO-TiO2 showed five-fold and two-fold enhancement for the visible light and UV light, respectively, for the photocatalytic mineralization of methylene blue dye as compared to commercial Aeroxide P25 TiO2. The excellent photocatalytic mineralization activity of (1:10) RGO-TiO2 could be attributed to the enhanced surface area of composite as well as to its good electron sink capability. (1:10) RGO-TiO2 could be recycled easily and was found to be equally efficient even after the fourth cycle for the photocatalytic mineralization of methylene blue dye. The non-selectivity of synthesized composite was checked by the mineralization studies of oxalic acid.

scholarly journals Constant Optical Power Operation of an Ultraviolet LED Controlled by a Smartphone

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4707
Author(s):  
Ching-Hua Chen ◽  
Jia-Jun Zhang ◽  
Chang-Han Wang ◽  
Yu-Chia Chang ◽  
Pinghui S. Yeh
Keyword(s):  
Uv Light ◽  
Light Output ◽  
Color Temperature ◽  
Constant Light ◽  
Driving Voltage ◽  
Light Power ◽  
Monolithically Integrated ◽  
Uv Led ◽  
Power Operation ◽  
Arduino Uno

Constant light power operation of an ultraviolet (UV) LED based on portable low-cost instrumentation and a monolithically integrated monitoring photodiode (MPD) has been reported for the first time. UV light irradiation has become one of the essential measures for disinfection and sterilization. Monitoring and maintaining a specified light power level is important to meet the criteria of sterilization. We built a module composed of a monolithically integrated UV LED and MPD, a transimpedance amplifier, an Arduino Uno card, a digital-to-analog converter and a Bluetooth transceiver. An Android App that we wrote remotely controlled the UV LED module via Bluetooth. The Arduino Uno card was programmed to receive demands from the smartphone, sent a driving voltage to the LED and returned the present MPD voltage to the smartphone. A feedback loop was used to adjust the LED voltage for maintaining a constant light output. We successfully demonstrated the functioning of remote control of the App, and the resultant UV LED measured power remained the same as the setting power. This setup can also be applied to visible or white LEDs for controlling/maintaining mixed light’s chromaticity coordinates or color temperature. With such controlling and internet capability, custom profiling and maintenance of precision lighting remotely would be possible.

scholarly journals TiO2-Powdered Activated Carbon (TiO2/PAC) for Removal and Photocatalytic Properties of 2-Methylisoborneol (2-MIB) in Water

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1622
Author(s):  
Xiao-Pin Guo ◽  
Peng Zang ◽  
Yong-Mei Li ◽  
Dong-Su Bi
Keyword(s):  
Activated Carbon ◽  
Natural Organic Matter ◽  
Uv Light ◽  
Sol Gel ◽  
Light Irradiation ◽  
Nano Tio2 ◽  
Uv Light Irradiation ◽  
Adsorption Capacities ◽  
Taste And Odor ◽  
Composite Photocatalysts

2-methylisoborneol (2-MIB) is a common taste and odor compound caused by off-flavor secondary metabolites, which represents one of the greatest challenges for drinking water utilities worldwide. A TiO2-coated activated carbon (TiO2/PAC) has been synthesized using the sol-gel method. A new TiO2/PAC photocatalyst has been successfully employed in photodegradation of 2-MIB under UV light irradiation. In addition, the combined results of XRD, SEM-EDX, FTIR and UV-Vis suggested that the nano-TiO2 had been successfully loaded on the surface of PAC. Experimental results of 2-MIB removal indicated that the adsorption capacities of PAC for 2-MIB were higher than that of TiO2/PAC. However, in the natural organic matter (NOM) bearing water, the removal efficiency of 2-MIB by TiO2/PAC and PAC were 97.8% and 65.4%, respectively, under UV light irradiation. Moreover, it was shown that the presence of NOMs had a distinct effect on the removal of MIB by TiO2/PAC and PAC. In addition, a simplified equivalent background compound (SEBC) model could not only be used to describe the competitive adsorption of MIB and NOM, but also represent the photocatalytic process. In comparison to other related studies, there are a few novel composite photocatalysts that could efficiently and rapidly remove MIB by the combination of adsorption and photocatalysis.

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