Decabromodiphenyl ether (BDE209) is a persistent aromatic compound widely associated with environmental pollutants. Given its persistence and possible bioaccumulation, exploring a feasible technique to eradicate BDE209 efficiently is critical for today’s environmentally sustainable societies. Herein, an advanced nanocomposite is elaborately constructed, in which a large number of titanium dioxide ( TiO2) nanoparticles are anchored uniformly on two-dimensional graphene oxide (GO) nanosheets ( TiO2/GO) via a modified Hummer’s method and subsequent solvothermal treatment to achieve efficient photocatalytic degradation BDE209. The obtained TiO2/ GO photocatalyst has excellent photocatalytic due to the intense coupling between conductive GO nanosheets and TiO2 nanoparticles. Under the optimal photocatalytic degradation test conditions, the degradation efficiency of BDE209 is more than 90%. In addition, this study also provides an efficient route for designing highly active catalytic materials.

In this investigation, Bi2MoO6 deposited graphene nanocomposite (BMG) was synthesized using a simple microwave assisted hydrothermal synthesis method. The synthesized BMG nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy dispersive X-ray analysis, and photocurrent analysis. The study revealed that the catalysts prepared have high crystalline nature, enhanced light responsive property, high catalytic activity, and good stability. XRD results of BMG composite exhibit a koechlinite phase of Bi2MoO6. The surface property is shown by SEM and TEM, which confirmed a homogenous composition in the bulk particles of Bi2MoO6 and nanosheets of graphene. The catalytic behavior was investigated by the decomposition of Rhodamine B as a standard dye. The results exhibit excellent yields of product derivatives at mild conditions under ultrasonic/visible light-medium. Approximately 1.6-times-enhanced sono-photocatalytic activity was observed by introduction of Bi2MoO6 on graphene nanosheet compared with control sample P25 during 50 min test.

To improve light absorption ability in the visible light region and the efficiency of the charge transfer reaction, Pd nanoparticles decorated with reduced TiO2 nanotube photocatalyst were synthesized. The reduced TiO2 nanotube photocatalyst was fabricated by anodic oxidation of Ti plate, followed by an electrochemical reduction process using applied cathodic potential. For TiO2 photocatalyst electrochemically reduced using an applied voltage of -1.3 V for 10 min, 38% of Ti4+ ions on TiO2 surface were converted to Ti3+ ion. The formation of Ti3+ species leads to the decrease in the band gap energy, resulting in an increase in the light absorption ability in the visible range. To obtain better photocatalytic efficiency, Pd nanoparticles were decorated through photoreduction process on the surface of reduced TiO2 nanotube photocatalyst (r10-TNT). The Pd nanoparticles decorated with reduced TiO2 nanotube photocatalyst exhibited enhanced photocurrent response, and high efficiency and rate constant for aniline blue degradation; these were ascribed to the synergistic effect of the new electronic state of the TiO2 band gap energy induced by formation of Ti3+ species on TiO2, and by improvement of the charge transfer reaction.

For the purpose of manufacturing a high efficiency TiO2 photocatalyst, B-doped TiO2 photocatalysts are synthesized using a plasma electrolytic oxidation method in 0.5 M H2SO4 electrolyte with different concentrations of H3BO3 as additive. For the B doped TiO2 layer fabricated from sulfuric electrolyte having a higher concentration of H3BO3 additive, the main XRD peaks of (101) and (200) anatase phase shift gradually toward the lower angle direction, indicating volume expansion of the TiO2 anatase lattice by incorporation of boron, when compared with TiO2 layers formed in sulfuric acid with lower concentration of additive. Moreover, XPS results indicate that the center of the binding energy peak of B1s increases from 191.45 eV to 191.98 eV, which suggests that most of boron atoms are doped interstitially in the TiO2 layer rather than substitutionally. The B doped TiO2 catalyst fabricated in sulfuric electrolyte with 1.0 M H3BO3 exhibits enhanced photocurrent response, and high efficiency and rate constant for dye degradation, which is ascribed to the synergistic effect of the new impurity energy band induced by introducing boron to the interstitial site and the improvement of charge transfer reaction.

Bi2MoO6 (BMO) via the structure-directing role of CO(NH2)2 is successfully prepared via a facile solvothermal route. The structure, morphology, and photocatalytic performance of the nanoflake BMO are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectrum analysis (PL), UV-vis spectroscopy (UVvis) and electrochemical test. SEM images show that the size of nanoflake BMO is about 50 ~ 200 nm. PL and electrochemical analysis show that the nanoflake BMO has a lower recombination rate of photogenerated carriers than particle BMO. The photocatalytic degradation of tetracycline hydrochloride (TC) by nanoflake BMO under visible light is investigated. The results show that the nanoflake BMO-3 has the highest degradation efficiency under visible light, and the degradation efficiency reached 75 % within 120 min, attributed to the unique hierarchical structure, efficient carrier separation and sufficient free radicals to generate active center synergies. The photocatalytic reaction mechanism of TC degradation on the nanoflake BMO is proposed.

PURPOSES : The purpose of this study was to analyze the effect of reducing nitrogen oxide concentration in a photocatalyst (titanium dioxide) using statistical methods such as the Anderson-Darling test. METHODS : To compare and analyze the effect of reducing the nitrogen oxide concentrations in titanium dioxide, titanium dioxide was applied to the public road, and data acquisition in terms of nitrogen oxide concentration was conducted from roads with/without applying titanium dioxide (test section and reference section, respectively). Then, the probabilities of occurrence of nitrogen oxide concentrations in the test and reference sections were estimated and compared using the Anderson-Darling test. RESULTS : According to the comparison and analysis of probabilities in the nitrogen oxide concentration of the test and reference sections, the probabilities of nitrogen oxide concentration on December 4th were estimated as ‘High’ (17.5%, 37.9%), ‘Moderate’ (30.5%, 40.8%), and ‘Low’ (52.0%, 21.3%), respectively, and on December 5th, as ‘High’ (20.6%, 39.1%), ‘Moderate’ (26.2%, 33.0%), and ‘Low’ (53.2%, 27.9%), respectively. In addition, the probabilities of nitrogen oxide concentration in the test and reference sections were analyzed on December 6th as ‘High’ (16.5%, 36.8%), ‘Moderate’ (27.9%, 38.5%), and ‘Low’ (55.6%, 24.8%), respectively. CONCLUSIONS : Based on the results of this study, in the test section with application of titanium dioxide, the nitrogen oxide concentration was found to have a low probability, and in the reference section, the nitrogen oxide concentration was found to be higher than that in the test section. Therefore, it can be concluded that titanium dioxide applied to road facilities has a nitrogen oxide reduction effect.

In this work, TiO2 3D nanostructures (TF30) were prepared via a facile wet chemical process using ammonium hexafluorotitanate. The synthesized 3D TiO2 nanostructures exhibited well-defined crystalline and hierarchical structures assembled from TiO2 nanorods with different thicknesses and diameters, which comprised numerous small beads. Moreover, the maximum specific surface area of TiO2 3D nanostructures was observed to be 191 m2g-1, with concentration of F ions on the surface being 2 at%. The TiO2 3D nanostructures were tested as photocatalysts under UV irradiation using Rhodamine B solution in order to determine their photocatalytic performance. The TiO2 3D nanostructures showed a higher photocatalytic activity than that of the other TiO2 samples, which was likely associated with the combined effects of a high crystallinity, unique features of the hierarchical structure, a high specific surface area, and the advantage of adsorbing F ions.

Tungsten trioxide (WO3) is a promising candidate as a photocatalyst because of its outstanding electrical and optical properties. In this study, we prepare WO3 thin films by electrodeposition and characterize the photocatalytic degradation of methylene blue using these films. Depending on the voltage conditions (static and pulse), compact and porous WO3 films are fabricated on a transparent ITO/glass substrate. The morphology and crystal structure of electrodeposited WO3 thin films are investigated by scanning electron microscopy, atomic force microscopy, and X-ray diffraction. An application of static voltage during electrodeposition yields a compact layer of WO3, whereas a highly porous morphology with nanoflakes is produced by a pulse voltage process. Compared to the compact film, the porous WO3 thin film shows better photocatalytic activities. Furthermore, a much higher reaction rate of degradation of methylene blue can be achieved after post-annealing of WO3 thin films.

Highly self-cleaning thin films of TiO2-SiO2 co-doped with Ag and F are prepared by the sol-gel method. The asprepared thin films consist of bottom SiO2 and top TiO2 layers which are modified by doping with F, Ag and F-Ag elements. XRD analysis confirms that the prepared thin film is a crystalline anatase phase. UV-vis spectra show that the light absorption of Ag-F-TiO2/SiO2 thin films is tuned in the visible region. The self-cleaning properties of the prepared films are evaluated by a water contact angle measurement under UV light irradiation. The photocatalytic performances of the thin films are studied using methylene blue dye under both UV and visible light irradiation. The Ag-F-TiO2/SiO2 thin films exhibit higher photocatalytic activity under both UV and visible light compared with other samples of pure TiO2, Ag-doped TiO2, and F-doped TiO2 films.

본 총설은 다양한 저널 게재 논문으로부터 분리막 및 광촉매의 혼성 정수/하수 처리 공정을 요약하였다. 이 총설에는 (1) 분리막 광촉매 반응기(membrane photoreactor, MPR), (2) 분리막 결합 광촉매 공정에서 막오염 관리, (3) 유기 오염 물의 분해를 위한 광촉매 분리막 반응기, (4) 정수처리용 막분리 공정과 광촉매 분해의 결합, (5) 휴믹산 분해를 위한 광촉매 및 세라믹 막여과의 혼성공정, (6) 활성슬러지 여과를 위한 한외여과의 막오염에 이산화티타늄 나노입자의 영향, (7) 정수처 리용 광촉매 및 정밀여과의 혼성시스템, (8) 선박 평형수 처리용 한외여과 및 광촉매의 혼성공정 및 (9) 분리막 및 광촉매 코팅 프로필렌 구의 혼성수처리 공정이 포함되어 있다.

This study shows the development of a photocatalytic technology for the road to decompose the nitrogen oxides(NOx) using a titanium oxide(TiO2) photocatalyst coating method for reducing the air pollution

Black pepper (piper nigrium L.) is a spice commonly used but has a problem with microbial control, so it needs non-thermal decontamination method for product quality of dried foods. Intense pulsed light (IPL) technology is a non-thermal method for superficial decontamination of foods to inactivate pathogenic microorganisms by using high peak power and short duration pulses of a broad-spectrum (170-2600 nm) using a xenon lamp. The objective of this study was to reduce total number of bacteria in ground black pepper effectively by combined treatments of IPL and immobilized TiO2 photocatalyst. Self-designed cyclone type of pilot-scaled IPL device (> 5 kg/h) was used, which makes samples to flow cyclonically in a vacuum space longer time rather than moving vertically. Using this device alone, without TiO2 coated, 0.3-0.6 log reductions were achieved under a total energy fluence of 14.85 J/cm2 (DC voltage; 1200, 1800, and 2400 V, pulse duty; 0.5, 2.1, and 3.0 ms, treatment time; 60, 120, 180, 240, and 300 s, frequency; 2 Hz). Subsequently, TiO2-coated quartz plates with different layers between light source and samples were installed to observe the effect of photocatalyst and the efficiency of decontamination was improved slightly. However to increase the effect of the photocatalyst, several factors (TiO2 particle size, TiO2 film thickness and transparency, adhesiveness between quartz and photocatalyst, etc.) need to be concerned additionally. Nevertheless, the application of IPL treatment combined with TiO2 photocatalyst offers a potential of effective non-thermal decontamination method for dealing with powder foods in food industry.

Cobalt-incorporated zeolitic imidazolate framework ZIF-8 was synthesized by a simple one-pot synthesis method at room temperature. Powder X-ray diffraction patterns and energy dispersive X-ray spectrum confirmed the formation of the bimetallic Co/Zn-ZIF structure. UV-Vis diffuse reflectance spectra revealed that the bimetallic ZIF had a lower HOMO-LUMO gap compared with ZIF-8 due to the charge transfer process from organic ligands to cobalt centers. A hydrolytic stability test showed that Co/Zn-ZIF is very robust in aqueous solution - the most important criterion for any material to be applied in photodegradation. The photocatalytic efficiency of the synthesized samples was investigated over the Indigo Carmine (IC) dye degradation under solar simulated irradiation. Cobalt incorporated ZIF-8 exhibited high efficiency over a wide range of pH and initial concentration. The degradation followed through three distinct stages: a slow initial stage, followed by an accelerated stage and completed with a decelerated stage. Moreover, the photocatalytic performance of the synthesized samples was highly improved in alkaline environment rather than in acidic or neutral environments, which may have been because in high pH medium, the increased concentration of hydroxyl ion facilitated the formation of hydroxyl radicals, a reactive species responsible for the breaking of the Indigo Carmine structure. Thus, Co/Zn-ZIF is a promising and green material for solving the environmental pollution caused by textile industries.

To improve photocatalytic performance, a PbS/ZnO/TiO2 nanotube catalyst was synthesized, and its surface characteristics and photocatalytic efficiency were investigated. The hybrid photocatalysts were produced by anodic oxidation and successive ionic layer adsorption and reaction(SILAR). The photocatalytic efficiency was evaluated using the dye degradation rate. The PbS/ZnO/TiO2 photocatalyst significantly enhanced the photocatalytic activity for dye degradation, which was ascribed to the synergistic effect of their better absorption of solar light and a decrease in the rate of excited electron-hole recombination.

본 연구에서는 알루미나 정밀여과 및 광촉매 코팅 폴리프로필렌의 혼성 수처리 공정에서 물역세척 시간 (back-flushing time, BT) 및 PP 구 변화의 영향을 알아보고, 알루미나 한외여과막와 동일한 PP 비드를 사용한 선행 결과와 비 교하였다. 물역세척 주기(FT)는 10분으로 고정한 채, BT를 6~30초로 변화시키면서, 그 영향을 180분 운전 후 막 오염에 의한 저항(Rf), 투과선속(J)과 총여과부피(VT) 측면에서 고찰하였다. BT가 길어질수록 Rf는 급격히 감소하고 J는 증가하였으나, VT는 BT 10초일 때 최대였다. 탁도의 처리효율은 99.0% 이상으로 BT의 영향이 보이지 않았다. 한편, 유기물 처리효율은 역세척 없 는 조건(NBF)에서 89.0%로 가장 높았으며, BT가 길어질수록 증가하였다. 막오염 측면에서 최적 PP 비드의 투입 농도는 20 g/L이었으나, 알루미나 한외여과막와 동일한 PP 비드를 사용한 선행 결과 최적 PP 비드의 농도는 40 g/L이었다. 탁도와 유기 물 처리효율은 PP 농도 30 g/L에서 최대였으나, 선행 결과 탁도와 유기물 처리효율은 모두 PP 농도 40 g/L에서 가장 높았다.

고도정수처리를 위한 관형 세라믹 정밀여과와 이산화티타늄(TiO₂) 광촉매 첨가 PES (polyethersulfone) 구의 혼성공정에서 pH 및 포화산소, 역세척 매체의 영향을 막오염에 의한 저항(Rf) 및 투과선속(J), 총처리수량(VT) 측면에서 물 또는 질소, 산소 역세척 결과를 비교하였다. pH가 증가할수록 Rf는 감소하였고 J과 VT는 증가하였다. 탁도 처리효율은 pH에 상관없이 물 또는 질소 역세척 모두 유사한 값을 보였고, 용존유기물(DOM) 처리효율은 물 역세척 시 일정한 경향을 보이지 않았다. Rf는 공급수를 산소로 포화시킨 무역세척(NBF)에서 포화산소(SO)가 없는 NBF보다 낮게 나타났다. DOM 처리효율도 SO가 있는 NBF에서 SO가 없는 NBF보다 낮게 나타났다. 이러한 결과는 SO가 광촉매 TiO₂와 반응하여 발생된 OH 라디칼이모듈 내에 채워진 물에 의해 희석되었기 때문이다. 역세척 주기 10분에서 물 역세척보다 기체 역세척 시 DOM 처리효율은큰 값을 보였다. 이러한 결과는 기체 역세척이 물 역세척보다 PES 구를 효과적으로 세척함으로써, PES 구에 의한 흡착과 광분해가 활발하게 진행되기 때문이다.

고도정수처리를 위한 관형 세라믹 정밀여과와 이산화티타늄(TiO2) 광촉매 첨가 PES (polyethersulfone) 구의 혼성공정에서 pH 및 산소 역세척의 영향을 막오염에 의한 저항(Rf) 및 투과선속(J), 총여과부피(VT)의 관점에서 고찰하였다. pH가높아질수록 Rf가 감소하고, J는 증가하는 경향을 보였다. 결과적으로 pH 9에서 최대의 VT를 나타내었다. 탁도의 처리효율은 pH와 무관하게 98.7∼99.0%의 비슷한 처리효율을 보였다. 용존유기물질(DOM)의 처리효율은 pH가 높아질수록 감소하였다.산소와 질소 역세척의 차이를 비교한 결과, Rf,180 값이 산소 역세척 시 질소보다 낮게 나타났고, 초기투과선속(J0)으로 무차원화한 최종투과선속(J180/J0)은 역세척 주기(FT) 10분과 12분을 제외하고 산소 역세척이 질소 보다 높게 유지되었다. 산소 역세척 시 탁도물질의 처리효율은 질소 보다 다소 높게 나타났지만, 그 차이는 미비하다. 질소 역세척 시 DOM의 처리율은 산소보다 높게 나타났다. 또한, 포화산소 조건에서 탁도물질의 처리율은 산소 또는 질소 역세척 경우와 비슷하게 나타났지만, 포화산소가 광촉매와 반응하여 OH 라디칼을 생성하였기 때문에 DOM의 처리효율은 큰 폭으로 증가하였다.