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Coffee is the second popular drink and second traded item in the world. Unfortunately, the process of coffee beverage preparation generates a huge solid waste, which is about 650 kg/ton or 2 kg wet spent coffee grounds (SCG) per 1 kg of soluble coffee. The high carbon content, high heating value, low ash, and negligible sulfur content of SCG makes it an alternative fuel source through thermochemical conversion. Therefore, this study investigated the thermochemical conversion of SCG with or without the presence of CO2 and/or steam gasification medium in the semi-fluidized bed reactor. Elemental composition, calorific value, proximate analysis, and thermal decomposition characteristics were analysed. Surface morphology of SCG was also carried by field emission scanning electron microscopy. The chemical characterization has shown about 50% C and more than 7% H2 content, nearly 23% HHV, and about 70% VOC, and 20% fixed carbon. The gasification process in the presence of CO2 and steam atmosphere also showed about 95% carbon conversion and nearly 72% cold gas efficiency.

A serial of carbon modified Ag/TiO2 photocatalysts have been synthesized with different carbon content by a simple co-impregnation method. Here, 1-pentanol was used as carbon precursor. The carbon modified Ag/TiO2 nanocomposites were characterized by X-ray diffraction, raman spectroscopy, thermal gravity analysis, UV–vis diffuse reflectance spectra, photoluminescence, and X-ray photoelectron spectroscopy. The photocatalytic removal of nitrogen oxides was carried out under both UV light and visible light irradiation. Our results revealed that carbon and silver species showed strong synergistic effect which significantly enhance the photocatalytic NOx removal on TiO2 photocatalyst under visible light irradiation.

Material-extrusion-type desktop 3D printers are popular nowadays, but there is usually no air quality control in their working environment. Since the printing process involves heating polymers, particle emissions of the particle diameter less than 2.5 mm became an important issue in consideration of “green” additive manufacturing. Besides, infill is commonly used in printing to reduce weight and time, but rare research studies the effects of infill in particle emissions. Hence, in this research, particle emission behaviors with the existence of infill were investigated. The measured particle concentrations of ABS samples showed a peak emission during the 1st top solid layer printing, which was the first layer after infill. Further experiments were conducted to evaluate the effects of infill height, infill density, infill pattern, and feed rate of the 1st top solid layer printing. Consequently, less infill height, higher infill density, and slower feed rate would lead to less particle emissions and a smaller peak value. The verification sample with preferred settings has demonstrated 96% improvement of the peak value. In the future practices, particle collecting device can be scheduled only limited to the period of peak emission to save cost and energy.

The redox performances of 1–10 wt% Na-modified Fe2O3/Al2O3 oxygen carrier from seawater were investigated using syngas/air as reactive gases in the thermogravimetric analyzer (TGA) and lab-scaled semi-fluidized bed reactor (semi-FzBR). NaNO3(aq) as the source of sodium dopants to prepare Na-contained solution was implemented by an air atmospheric pressure plasma jet (Air-APPJ) process, which can increase the feasibility of seawater. For the prepared samples, the materials properties, including crystalline phases, surface morphologies, surface areas, and attrition loss performances were well correlated with the Na contents. The results indicated that the poor reduction kinetics and attrition resistance were obtained with the Na adjunction over 5 wt%, attributing to the sintering issue on excessive phases of Na2(Al, Fe)12O19 and Na(Al, Fe)O2 solid solution in the samples. Therefore, the slight incorporation of Na content in the Fe2O3/Al2O3 samples which improved the reduction rate was proved as the candidate oxygen carriers. Particularly, the Na content with 1 wt% in Fe2O3/Al2O3 sample (Na1FA32) can significantly promote the reduction behavior, thermal stability, and attrition resistance as compared to the raw Fe2O3/Al2O3 oxygen carrier. It is environmentally beneficial to use the Na1FA32 as oxygen carrier in a practical chemical looping combustion process.

Lead (Pb) nanowire arrays were fabricated with anodic aluminum oxide (AAO) templates of 30, 100 and 300 nm in pore diameters. Through vacuum injection molding process, Pb/AAO composite was obtained, and lead sulfide (PbS) could further be synthesized after exposing to sulfur gas. AAO templates with different pore sizes were fabricated by using pure aluminum in a two-step anodization. Three types of solutions, which are 10 vol% sulfuric acid, 3 wt% oxalic acid and 1 vol% phosphoric acid, were adopted to achieve AAO of various pore sizes. Different sulfurization temperatures and time spans were applied for studying on the formation mechanism of PbS. Finally, the morphology, composition, structure and elements distribution of the as-prepared Pb and PbS nanowires were confirmed through the use of scanning electron microscopy, energy dispersive x-ray spectroscopy, element-mapping, x-ray diffraction and transmission electron microscopy analysis. The results indicated that Pb nanowires were successfully obtained after applying vacuum injection molding process with 50 kgf cm−2 hydraulic pressure, and PbS nano arrays can be formed by sulfurization at 500 °C for 5 h. Furthermore, an optical property, ultraviolet–visible (UV–Vis) absorption, was also measured. The measurement of the PbS nanowires showed that a significant quantum confinement effect made the energy gap produce a blue shift from 0.41 eV to 1.65 eV or 1.72 eV.

Objective Developments in electroencephalography (EEG) technology has allowed the use of brain-computer interface (BCI) outside dedicated labs. In order to achieve long-time monitoring and detection of EEG signals for BCI application, dry electrodes with good signal quality and high bio compatibility are essential. In 2016, we proposed a flexible dry electrode made of silicone gel and Ag flakes, which showed good signal quality and mechanical robustness. However, the Ag componets used made the electrode too expensive for commercial adaptation. In this study, we aim to develop an improved electrode based on our previous design. Approach The new electrode was produced from silicone gel, metal flakes and graphene/GO. Two types of electrode with different graphene/GO proportion were produced to explore how the amount of graphene/GO affects the electrode. We also designed tests to test the electrodes' signal quality and robustness in detecting steady state visually evoked potential (SSVEP). Main results During our tests, the proposed elextrodes showed low impedance and had good signal correlation to conventional wet electrode in both time domain and frequency domain. The graphene/GO electrode also showed good signal quality in eyes opened EEG recording. Curiously, we found that the electrode with more graphene/GO had uneven surface and had worse signal quality. Finally, we sound the graphene/GO electrode could reliably detect SSVEP in target bfrequency and harmonic frequencies even in hairy occipital area. Significance This study proposed a new flexible dry electrode that was easy to prepare and can be made into various shape. This makes the electrode easily adaptable to existing EEG systems. The electrode showed high signal correlation to conventional wet electrode, and can reliably detect SSVEP. These traits give the proposed electrode a huge potential in commercial BCI.

The use of seawater as catalytic agents for hematite (Fe 2 O 3 ) as oxygen carrier in chemical looping combustion process is attractive, because of its abundance and low cost. Unfortunately, seawater itself with major NaCl compound under reactive species accompanying the volatilization of chlorine-containing gases probably lead to the corrosion on reactors during the combustion process. In this study, the feasibility evaluation of sodium dopants extracted from seawater as an effective catalytic agent via an air atmospheric pressure plasma jet (Air-APPJ) is performed, and as such it is combined with Fe 2 O 3 /Al 2 O 3 to assess any possible enhancement on the reduction kinetics. The sodium-contained solutions, NaNO 3(aq) and NaCl (aq) , as precursors are used to prepare the sodium dopants due to the evaporation-decomposition of water and dissolved salts via plasma discharge reaction. The sodium-modified Fe 2 O 3 /Al 2 O 3 oxygen carrier can significantly promote the efficiency of the carbon capture efficiency and CO 2 yield. Especially for the NaCl (aq) as precursor in an Air-APPJ system, the high carbon capture efficiency, CO 2 molar fraction and CO 2 yield around 0.96, 0.95 and 0.91 after fifty redox cycle for the sodium-modified Fe 2 O 3 /Al 2 O 3 oxygen carrier are achieved. It can be anticipated that the sodium-modified Fe 2 O 3 /Al 2 O 3 from seawater by an Air-APPJ system as an oxygen carrier candidate in a reversible CLC process would be notably attractive.

Fe-based oxygen carriers supported by Al2O3 and TiO2 were prepared as pellets for chemical looping combustion in this study. Over 90% conversions were obtained for most experiments operated in the TGA; however, experiments conducted with FeTi320 pellets exhibited higher conversions than those with FeAl320. The prepared pellets sintered at higher temperatures always exhibited higher crush strength. The crush strength of prepared FeAl320 and FeTi320 pellets were decreased for experiments conducted with greater starch content, because the more pore spaces are formed in the original places of the starch grains. For experiments conducted in the fixed bed reactor, the prepared pellets exhibited relatively high conversion. The conversions of FeTi320 were remained to be about 80% with increasing starch content because high porosity (approximately 50%) was formed for 0–20% starch contents of FeTi320 pellets after 10 redox cycles. Less porosity was formed after 20 redox cycles for experiments conducted with FeAl320 pellets prepared with higher starch contents. Therefore, the conversion of FeAl320 pellets was elevated with increasing starch content. Iron content for inner part of prepared pellets was significantly decreased after operated for 20 redox cycles, while iron content for outer part of pellets were increased. It is suggested that the iron ions may diffuse onto the surface of oxygen carriers to react with oxygen during the oxidation period.

Thermostability study of commercial P25 TiO2 nanoparticles was carried out by ascending annealing temperature from 400 to 1100 C. The thermostability of TiO2 structure was measured by X-ray diffraction (XRD). Anatase-Rutile phase transition occurred only when temperature exceeds 600C. Rutile weight fraction increased from 25 to 100 % between 400 to 840 C. Phase transition activation energy was calculated by using Arrenhius plot to be 27 kJ/mol. Transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET), and dynamic light scattering (DLS) techniques were applied to determine the size of grown particles. Results of particle size analysis using TEM imaging method were the same as those using BET instruments up to 840 C. BET measurements tend to overestimate the particle size at temperature greater than 840 C. In contrast, DLS overestimate the size of TiO2 particles due to agglomeration in solution. Mean TiO2 particle sizes grew from 25 to 450 nm when temperature increased from 400 to 1100 C. Furthermore, the photocatalytic reactivity in the degradation of dye decreased with the increase of particle size and rutile fraction.

The characteristics and application of TiO2-supported Fe2O3 oxygen carriers were investigated for chemical looping combustion (CLC) and hydrogen generation (CLHG) in this study. Prepared Fe2O3/TiO2 oxygen carriers with 20–30 wt% of TiO2 were demonstrated to achieve satisfactory results even after 30-cycle operation by thermogravimetric analyzer (TGA). Oxygen carriers contain more than 33 wt% TiO2 were observed to be more porous and fragile after continuous high-temperature operation. Conversely, the reactivity of oxygen carriers contain less 10 wt% TiO2 was rapidly decayed after operated for merely 3 redox cycles because of their dense structure. The CO2 and H2 conversions through syngas combustion and steam oxidation, respectively, for experiments were demonstrated to be feasible using sieved oxygen carriers at higher operation temperatures from 400 to 1000°C in fixed bed reactor (FBR) system.

Rice husk used as solid fuel for chemical looping combustion (CLC) with Fe2O3/Al2O3 oxygen carriers was investigated in an annular dual-tube moving bed reactor (ADMBR). Nearly 100% of CO2 concentration and 92% fuel conversion were achieved for rice husk combustion conducted with Fe2O3/Al2O3 mass flow rates of 22.7 g/min. The introduction of rice husk/sawdust and rice husk/charcoal and mixtures enhanced the processing capacity because of the higher carbon content. The heat demands for ADMBR were estimated to be roughly 54% of input processing capacity released for both rice husk and rice husk/sawdust gasification, while about 19% of input processing capacity was released for rice husk/charcoal gasification. ADMBR is technically feasible to be served as the fuel reactor for rice husk combustion by CLC to achieve high fuel conversion under appropriate operating conditions without auxiliary fuel.

Chemical looping hydrogen generation (CLHG), as a new technology involved in chemical looping combustion (CLC) process and steam-iron process, has attracted attention for clean energy generation and efficient energy conversion. A systematic investigation of spinel NiFeAlO4 has led to characterization of a well-defined self-supported oxygen carrier which was prepared by solid state reaction. The redox behavior of NiFeAlO4 shows the enhancement on the resistance to agglomeration exceeding previously reported CLC process using similar compositions including Fe2O3, NiO and NiFe2O4 without any inert support. Moreover, the high CO2 conversion and H2 generation by NiFeAlO4 oxygen carrier under a fixed-bed reactor (FxBR) were obtained. The reaction mechanism of NiFeAlO4 subjected to the isothermal stepwise reduction in a sequence of varying durations by XRD was also demonstrated, which provided with a novel function of self-supported and agglomeration-resistant characteristic in the oxygen carrier system.

Polyurethane (PU) and polypropylene (PP) particles were evaluated as solid fuels in chemical looping combustion (CLC) for treatment of waste plastics as well as power generation. An annular duel-tube moving bed reactor (ADMBR) was used as fuel reactor for decomposition and combustion of PU and PP particles. CO and H 2 were the major components of fuel gas generated by decomposition of PU and PP particles in the ADMBR. Complete conversion of plastic particles and 100% CO 2 yield of fuel gas were achieved as oxygen carrier-to-fuel ratio of PU and PP particles reached 1.86 and 6.56, respectively. The heat demands for ADMBR were calculated to be 21% and 52% of output processing capacity by heat consumptions of fuel decomposition in the fuel reactor of CLC system, respectively. ADMBR is technically feasible as fuel reactor for PU and PP combustion to achieve high conversion efficiency without auxiliary fuel by CLC.

The relative abundance and low cost of electric arc furnace dust (EAFD) make it a viable oxygen carrier for chemical looping combustion (CLC) system. Under a reducing agent, zinc ferrite (ZnFe2O4) phase in EAFD releases zinc vapor in a complex gas-solid reaction. In an effort to suppress the emission of zinc vapor, the reaction mechanism of ZnFe2O4 prepared as an oxygen carrier in a redox cycling test is primarily discussed, as well as the issue of coupling with an inert Al2O3 support. The study focused the investigation on redox cycling behavior and CO2 conversion in ZnFe2O4/Al2O3 and EAFD/Al2O3 systems using a thermogravimetric analyzer (TGA) and fixed-bed reactor (FxBR). In a lab-scaled semi-fluidized bed reactor (semi-FzBR) of EAFD/Al2O3 as an oxygen carrier system, a high CO gas yield approximately 0.98 after fifty redox cycles is also experimentally obtained. It can be anticipated that the use of EAFD/Al2O3 system as an oxygen carrier in a reversible CLC process could be economical and environmentally beneficial.

Fe2TiO5 was studied for the reduction mechanism in chemical looping process. Fe2TiO5 pellets were reduced by syngas that demonstrated highest reduction rate in the beginning of reduction period from Fe2TiO5 to FeTiO3 and Fe2TiO4. The reduction of Fe2TiO5 is suggested in sequence from Fe2TiO4, FeTiO3 to Fe. Fe2TiO5 pellets performed reasonable reactivity and steady recyclability after continuous 100 redox cycles. The increased surface area and decreased mechanical strength for pellets operated after 30 redox cycles was due to formation of cracks and porous structures. Moreover, Fe2O3/TiO2 was the major crystalline phase existed in the pellets after 30 redox cycles. Fe2TiO5 attributed high syngas conversion in the fixed bed reactor due to high equilibrium constants. The completed reduced form of Fe2TiO5 oxygen carriers, Fe/TiO2, demonstrated hydrogen generation by steam oxidation, and the Fe was oxidized to Fe3O4 and FeTiO3 in the fixed bed reactor.

It is here demonstrated that proton-intercalation via negative potential biases enhance the rate constant of methylene blue (MB) photo-electrocatalytic de-colorization on n-type tungsten trioxide hydrate (WO3·0.33H2O as prepared by hydrothermal synthesis), rather than the positive potential bias in promoting the charge separation of photo-generated electrons/holes. Due to the generation of W(V) and W(IV) hydroxyl species with smaller band gaps (in comparison with W(VI)) and the electrochemical activation of WO3·0.33H2O, negatively biased proton intercalation into WO3·0.33H2O clearly enhances its photo-electrocatalytic activity for MB de-colorization, including its visible-light photo-electrocatalytic activity. A possible scheme for promoting the photocatalytic activity of WO3·0.33H2O through proton intercalation under constant potential biases is proposed and discussed. The photocatalytic de-colorization rate of MB on UV100-TiO2 is significantly decreased under the same potential biases due to the difficulty in proton-intercalation

Chemical-looping combustion (CLC) of fossil fuel has a potential to generate power with achieving the inherent CO2 capture by means of an oxygen carrier (OC) that is circulated between air and fuel reactors. In this article, a composite oxygen carrier with highly redox reactivity for chemical-looping combustion process was first synthesized using nickel nitrate and iron nitrate as precursors in a sol–gel process, respectively. Materials characterization of the prepared OC samples were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurements, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). The reactivity of the oxygen carrier in CLC process was evaluated by a thermogravimetric analyzer by alternating methane and air. The prepared nickel–iron composites oxygen carrier exhibited excellent oxygen-transfer capability both in the fuel and air reactors than pure Fe2O3, NiO, NiFe2O4, and physically mixed Fe2O3–NiO samples. The synergistic effect between Fe and Ni cations can enhance the reduction rate of iron oxide; meanwhile, it also improves the oxidation reaction rate of metallic nickel. The different migration behaviours of iron and nickel under the reducing and oxidizing atmospheres were observed by XRD and EDX, respectively. Finally, twenty-cycles of redox reaction demonstrated that composites oxygen carrier loaded on the SiC inert support had excellent redox activity and sintering resistance and consequently was capable of the CLC process.

Fe 2 O 3 /Al 2 O 3 composite oxygen carriers were prepared for chemical looping combustion (CLC) with methane in a lab-scale moving bed fuel reactor provided with reasonable crush strength, reactivity and recyclability. Carbon formation was observed during the combustion process in the empty bed at 900 °C through methane decomposition reaction, and was enhanced for experiments conducted with increased retention time. Carbon formation was obviously reduced for experiments conducted in the moving bed fuel reactor with oxygen carrier-to-fuel ratio ( ϕ ) higher than 1.14. The oxygen carriers that moving out of the moving bed reactor were composed of mainly FeO and FeAl 2 O 4 , characterized by X-ray diffraction (XRD) analysis. The formation of FeO and FeAl 2 O 4 indicated that further utilization of oxygen in iron-based oxygen carriers can be achieved by moving bed operation.

The reactivity and high fuel conversion efficiency of metal oxide as oxygen carrier are two of the most important functions that can be research in order to make chemical looping combustion (CLC) a reality. In this study, oxygen carriers of Fe 2 O 3 , supported by titanium oxides were prepared to evaluate the feasibility as oxygen carriers for chemical looping by thermogravimetric analyzer (TGA), as well as gas conversion in a fixed bed reactor (FBR). Supported Fe 2 O 3 oxygen carriers and sintered in air at 1100C is a suitable preparation parameter to demonstrate reasonable oxygen conversion. The reduction mechanism of supported Fe 2 O 3 oxygen carriers were proposed in accordance with TGA and x-ray diffraction analysis (XRD) characterizations. Fe 2 TiO 5 and inherent TiO 2 as supporting material would be formed and carried on FBR in practical operation. The preparation of FT-03 (80% Fe 2 O 3 and 20% TiO 2 ) oxygen carrier demonstrated high CO 2 yields regarding to syngas (10% H 2 and 10% CO in N 2 ) and methane (10% CH 4 in N 2 ) combustion in FBR, operated at temperatures higher than 500 and 900C, respectively. Moreover, great mechanical strength and reasonable reactivity of supported Fe 2 O 3 oxygen carriers were also examined by texture analyzer with well-suited for used in CLC.

The bactericidal activity of conventional titanium dioxide (TiO2) photocatalyst is effective only on irradiation by ultraviolet light, which restricts the applications of TiO2 for use in living environments. Recently, carbon-containing TiO2 nanoparticles [TiO2(C) NP] were found to be a visible-light-responsive photocatalyst (VLRP), which displayed significantly enhanced antibacterial properties under visible light illumination. However, whether TiO2(C) NPs exert antibacterial properties against Bacillus anthracis remains elusive. Here, we evaluated these VLRP NPs in the reduction of anthrax-induced pathogenesis. Bacteria-killing experiments indicated that a significantly higher proportion (40%–60%) of all tested Bacillus species, including B. subtilis, B. cereus, B. thuringiensis, and B. anthracis, were considerably eliminated by TiO2(C) NPs. Toxin inactivation analysis further suggested that the TiO2(C) NPs efficiently detoxify approximately 90% of tested anthrax lethal toxin, a major virulence factor of anthrax. Notably, macrophage clearance experiments further suggested that, even under suboptimal conditions without considerable bacterial killing, the TiO2(C) NP-mediated photocatalysis still exhibited antibacterial properties through the reduction of bacterial resistance against macrophage killing. Our results collectively suggested that TiO2(C) NP is a conceptually feasible anti-anthrax material, and the relevant technologies described herein may be useful in the development of new strategies against anthrax.

In this work, several kinds of quaternary ammonium-based room-temperature ionic liquids (QA RTILs) are synthesized by alkylation and ion-exchange reactions for the rapid dissolution of cellulose. The applications of cellulose materials have been limited due to their poor solubility in conventional organic solvents, because of a high degree of structural regularity and a large number of hydrogen bonds. The prepared ionic liquids were identified by nuclear magnetic resonance, elemental analysis, and liquid chromatography-mass spectrometry. The results indicated that N,N,N-triethylhexan-1-aminium acetate (N6222OAc), tetrahexylammonium acetate (N6666OAc), and N,N,N,N&prime, N&prime, hexaethyldecane-1,10-diaminium acetate (C10(N222OAc)2) exhibited good cellulose-dissolution without any pretreatment. The regenerated cellulose films with a low degree of crystallization of the cellulose II phase were also prepared easily in this process using N6222OAc due to its polar and small cation. These QA RTILs can be used as non-derivatizing solvents for cellulose and can also be easily recycled because of their thermostable and nonvolatile properties.

Isopropanol (IPA) solution as liquid fuel for chemical looping combustion (CLC) with Fe2O3/Al2O3 oxygen carriers was investigated by a moving bed reactor. CO and H2 were the fuel gases generated by IPA solution in the moving bed reactor prior to combustion with oxygen carriers. The yields of fuel gas generated from IPA solution were determined to modify the equation of oxygen carrier-to-fuel ratio for moving bed operation. The IPA conversion and CO2 yield in the outlet stream from moving bed reactor reached 100% as oxygen carrier-to-fuel ratio was higher than 7.94 at 900 °C. Heat balance for input and output processing capacities is approximately achieved by theoretical estimation. By analysis of system processing capacity, 70% of output processing capacity is available for energy use of external facility. By analysis of processing efficiency, aqueous solution as liquid fuel would cause considerable heat consumption for water evaporation, especially for dilute solution. Chemical looping combustion is sugg...

Antibacterial activity of photocatalytic substrates is primarily induced by ultraviolet light irradiation. Visible light–responsive photocatalysts were recently discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. The development of antibacterial photocatalysts, however, has mainly focused on titanium oxide (TiO 2 )–related materials with antibacterial properties not comparable with conventional chemical disinfectants. This study demonstrated that a core-shell structured In 2 O 3 @CaIn 2 O 4 substrate has superior visible light–induced bactericidal properties, as compared with several commercially available and laboratory-prepared visible light–responsive photocatalysts. The high performance is enhanced by more easily photoexcited electron transfer between the interfaces of In 2 O 3 and CaIn 2 O 4 to minimize the electron-hole recombination during photocatalysis. Additionally, when compared with TiO 2 -based photocatalysts, In 2 O 3 @CaIn 2 O 4 treatments did not induce significant cell death and tissue damage, implying a superior biocompatibility. These findings suggest that In 2 O 3 @CaIn 2 O 4 may have potential application in the development of a safer and highly bactericidal photocatalyst. From the Clinical Editor A photocatalytic susbstrate is described that functions in visible light, possesses bactericidal properties and better biocompatibility than the standard TiO 2 based methods.

In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

Ultraviolet- and visible-light-responsive titania was synthesized and employed in the photomineralization of NOx and dyes. A carbon-modified titania photocatalyst was prepared by an impregnation method using anatase TiO2 particles as the raw material and ethanol as the carbon source. Carbon-containing titanium dioxide with the anatase phase prepared at 200 °C, exhibited high photocatalytic activity for the degradation of gaseous NOx and decolorization of aqueous methyl orange under visible-light illumination. The calcination temperature in this impregnation process plays an important role in the formation and resultant content of carbonaceous structure on TiO2 surface and affects both the optical and the photocatalytic properties of TiO2. The carbonaceous species on the TiO2 surface, shown by photoluminescence spectroscopy, Raman, UV–vis, infrared spectroscopy, and X-ray photoelectron spectroscopes, plays an important role in the visible-light absorption and photocatalytic degradation rates for NOx and methyl orange.

Nitrogen-doped titania (N-doped TiO2) and nitrogen-carbon co-doped titania (N-C-doped TiO2) were prepared in metal-organic chemical vapor deposition (MOCVD) processes under the controlled reaction atmosphere. The N-doped TiO2 and N-C-doped TiO2 with anatase phase were prepared at 600Â oC under N2-O2-NH3 and N2-NH3 atmospheres respectively. The N-C-doped TiO2 exhibited the high photocatalytic activity for the oxidation of NO under visible-light illuminations. The chamber atmosphere in the MOCVD process plays an important role on the surface lattice structure and nitrogen and carbon content of TiO2. The nitrogen and carbonaceous species on the TiO2 surface, evidenced from X-ray diffractometry (XRD), UV-VIS, and Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), were inferred as important factors for narrowing band gap of titania and enhancement of its visible-light-responsive activity.

Carbon-modified titania (C–TiO2) films were easily prepared by using an impregnation process with a glucose-containing TiO2 sol. Through controlling calcination conditions, the as-obtained C–TiO2 products exhibited highly photocatalytic activity for the degradation of gaseous NOx under visible light and ultraviolet illumination. The effects of carbon content and calcination temperature on the photocatalytic performances and their photochemical and physical properties were investigated. Carbonaceous species on the TiO2 surface enhanced the visible-light absorption of TiO2 films; however, an excessive amount of carbon on the TiO2 surface reduced its photocatalytic ability due to the serious coverage effect on active sites. The results show that a suitable glucose addition is about 50–100% of the weight of TiO2 content and the optimized calcination temperature is 300 °C, which leads to better photocatalytic activity under ultraviolet and visible- light irradiations. Accordingly, the simple-prepared C–TiO2 films functioned as visible-light-responsive catalysts, allowing for a feasible producing route for real applications.

The visible light active catalysts, PtOx-doped TiO2 (PtOx–TiO2) and PtOx-loaded TiO2 (PtOx/TiO2), were successfully synthesized by the acid-catalyzed sol–gel process and the impregnation method. Pt(NH3)4(NO3)2 or H2Pt(OH)6 was employed as the PtOx precursor. By comparing the results of De-NOx, the modified photocatalysts exhibited a higher visible-light-responsive activity, and a lower NO2 selectivity than the unmodified ones. The FE-SEM images suggested that the particle size was unchanged after modification. The XRD patterns showed that the crystal structure still remained as anatase phase. Nitrogen adsorption revealed no significant change in surface areas for all samples. The UV–vis spectra indicated that PtOx promoted the absorption of visible light. Furthermore, the XPS spectra evidenced that the mixed valence states of PtO–PtO2 coexisted on the surface of TiO2. The adding of PtOx on TiO2 not only promoted the visible-light-responsive activity of converting NO to NO2 but also increased the consecutive reaction rate of NO2 to NO3−.

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) nanoparticles were synthesized using calcining calcium dihydrogenphosphate (Ca(H2PO4)2 · H2O), calcium hydroxide (Ca(OH)2), and polyethylene glycol (PEG) at 900 °C in an oxygen atmosphere. This one-step process yields HA nanoparticles with similar particle sizes (e.g., 50–80 nm) that are well-crystallized and non-aggregated. PEG is an important factor in controlling the particle size, crystal phase, and degree of aggregation in these HA particles. This conclusion is supported by results from a field-emission scanning electron microscope (FE-SEM), X-ray diffractometry (XRD), energy dispersive X-ray analysis (EDS), a high-resolution transmission electron microscope (HR-TEM), and dynamic light scattering (DLS).

Photoactivities of the carbon-containing nano-structured titanium dioxide (TiO 2 ) prepared using a modified sol–gel method as visible-light-responsive photocatalysts were studied. This research aimed to compare four carbon-containing TiO 2 samples, prepared in different conditions, with a commercial nano-structured TiO 2 powders. The prepared titanium dioxide powders were analyzed using Raman spectroscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy. It is found carbon-containing TiO 2 nanoparticles prepared under calcinations at 200 °C exhibited high photocatalytic activity for decoloring of methylene blue and the removal of nitrogen monoxide under both ultraviolet and visible-light illumination. The calcination temperature and incorporated carbons affect the particle size and lattice structure of TiO 2 , and hence the photoactivities. The superior photocatalytic effects were attributed to the carbon-containing mixed anatase and rutile phase in the crystal structure of the TiO 2 .

Ultraviolet and visible-light-responsive titania was synthesized and employed in the NOx photomineralization. A thermal decomposition reaction of titanium isopropoxide was carried out with a metal-organic chemical vapor deposition (MOCVD), enabling continuous production of TiO2 nanoparticles. Carbon-containing titanium dioxide with the anatase phase prepared at 500 °C under nitrogen atmosphere exhibited high photocatalytic activity for NO oxidation under visible-light illumination. Experimental results indicate that up to 48% removal of NOx can be achieved in a continuous flow type of reaction system under visible-light illumination (green LED). The chamber temperature in this MOCVD process plays an important role in lattice structure formation, and also affected TiO2 carbon content. The carbonaceous species on the TiO2 surface, shown by X-ray diffractometry (XRD), and Raman, UV–vis, and X-ray photoelectron spectroscopies (XPS), is important to the visible-light absorption and visible-light-catalytic mineralization of NOx.

Anatase TiO2 nanocrystallines (17–29 nm) were successfully synthesized by the metal–organic chemical vapor deposition method (MOCVD). Moderate manipulation of system parameters of MOCVD can control the particle size. The electro-optical and photocatalytic properties of the synthesized TiO2 nanoparticles were studied along with several commercially available ultra-fine TiO2 particles (e.g., 3.8–5.7 nm). The band gap of the TiO2 crystallines was determined using the transformed diffuse reflectance technique according to the Kubelka–Munk theory. Results showed that the band gap of TiO2 monotonically decreased from 3.239 to 3.173 eV when the particle size decreased from 29 to 17 nm and then increased from 3.173 to 3.289 eV as the particle size decreased from 17 to 3.8 nm. The results of band gap change as a function of particle size agreed well with what was predicted by the Brus’ equation, i.e., the effective mass model (EMM). However, results of the photocatalytic oxidation of 2-chlorophenol (2-CP), showed that the smaller the particle size, the faster the degradation rate. This is attributed in part to the combined effect of band gap change relative to the spectrum of the light source and the specific surface area (or particle size) of the photocatalysts. The change of band gap due to particle size represents only a small optical absorption window with respect to the total spectrum of the light source, i.e., from 380 to 400 nm versus >280 nm. Consequently, the gain in optical property of the larger particles was severely compromised by their decrease in specific surface area. Our results clearly indicated the importance of specific surface area in controlling the photocatalytic reactivity of photocatalysts. Results also showed that the secondary particle size grew with time due mainly to particle aggregation. The photocatalytic rate constants decreased exponentially with increase in primary particle size. Primary particle size alone is able to predict the photocatalytic rate as it is closely related to the electro-optical properties of photocatalysts.

Thermostability of P25 nanoparticle was carried out by ascending thermal annealing. The growth of particle was observed and the activation energy of phase transition was calculated. The photocatalytic reactivity was measured in terms of the degradation rate of methylene blue. Results indicated that the specific surface area and the aggregation of TiO2 are much important factors than the crystal phase on the photo-decoloration reaction.

The reactions of alcohols and alkyl halides to synthesize di-ether compounds under phase-transfer catalysis conditions were carried out in an alkaline solution/organic solvent two-phase medium. Accordingly, the concentrations of alkyl halide, di-ether compound, active intermediate (QOR), and hydration number of active intermediate (QOR) were measured during these reactions. The fractional factorial design (FFD) method was first employed to study the effects of single factors and the effects of their interactions on the PTC reaction. The following reaction conditions (or factors) were investigated in the present FFD analysis: amount of alkaline salt, temperature, amount of water, amount of catalyst, volume of organic solvent, and agitation speed. A polynomial model and an analysis of variance table (ANOVA) were developed to connect the reaction conditions and the conversion from statistical results. Plots of the partition coefficient of alcohol between organic and aqueous phase, the concentration ...

The novel phase-transfer catalysts S-8 (dimethyloctyl(3-sulfopropyl) ammonium betaine) and DB-2 (di-active site quaternary ammonium salts) were synthesized and employed as the phase-transfer catalysts for synthesizing thioethers from various alkyl bromides of high conversion.

The reaction between sodium sulfide (Na2S) and n-bromobutane (1-C4H9Br) to synthesize di-n-butyl sulfide (RSR; R: C4H9) was carried out for in an organic solvent/alkaline solution two-phase medium under phase transfer catalysis (PTC) conditions. A rational reaction mechanism and a kinetic model were satisfactorily developed by considering the reactions from which two sites of nucleophiles on a molecule displaced the organic-phase reactant. The two-film theory, which includes mass transfer and phase equilibrium of the catalysts between two phases, was employed to describe the dynamic behavior of the reaction system. In this system, the two-site active catalyst, QSQ (Q+: (C4H9)4N+), which was produced from the reaction of sodium sulfide and quaternary ammonium salt, was first synthesized in the aqueous phase, and then transferred to the organic phase in preparation for further reaction. QSR was produced from the first reaction of the organic solution, and RSR was produced from the second reaction of the organic solution. Neither of these two-site active catalysts were isolated from the solution, nor were they detected from the solution during the reaction. Only the first apparent constant of the organic-phase reaction (kapp,1) was obtained via experimental data. Detailed investigation was made for: effect of agitation, temperature, amount of sodium sulfide, organic solvents, catalysts, amount of TBAB catalyst, amount of sodium hydroxide, volume of sodium sulfide solution, volume of organic solvent, and amount of water on the reaction rate and the conversion. The results were explained satisfactorily by considering the interaction between the reactants and the environmental species.

The reaction of 4,4′-biphenol and two species of bromoalkanes (e.g., bromoethane and 1-bromobutane) to synthesize two symmetric products (4,4′-diethanoxy biphenyl and 4,4′-dibutanoxy biphenyl) and one asymmetric product (4-ethanoxy, 4′-butanoxy biphenyl) was successfully carried out under two-phase phase-transfer catalysis conditions. A rational mechanism and kinetic model were built up by considering the reactions both in aqueous phase and in organic phase. The first active catalyst (QO(Ph)2OQ) was also synthesized under two-phase reaction and was identified by instruments. The experimental data were explained satisfactorily by the pseudo-steady-state hypothesis. Two sets of rate constants of organic reactions, i.e. primary (k1 and k2) and secondary (k11, k12, k21, and k22) rate constants participate in the kinetic model. The two primary rate constants were obtained individually via experimental data for synthesizing the symmetric products. The ratios of the other four secondary rate constants were obtained from the reaction of synthesizing asymmetric products and determined from the initial yield rates of symmetric products. The effects of the ratio of bromoethane and 1-bromobutane, temperature, organic solvents, amount of catalyst, and amount of sodium hydroxide on the reaction rate and the selectivity of products were investigated in detail. The results were explained satisfactorily by the interaction between the reactants and the environmental species. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 139–153, 2003

The reaction between 4,4′-biphenol (HO(Ph) 2 OH) and bromoethane (C 2 H 5 Br) was first carried out to synthesize 4,4′-diethanoxy biphenyl in an organic solvent/alkaline solution of NaOH two-phase medium under phase transfer catalytic condition. Rational reaction mechanism and kinetic model were built up by considering the reactions from which two sites of nucleophiles on a molecule attacked the organic phase reactant. The mass transfer and the phase equilibrium of the catalysts between two phases were constructed by the two-film theory. In this system, two active catalysts (QO(Ph) 2 OQ produced from the aqueous phase, and QO(Ph) 2 OR produced from the organic phase) were proposed to synthesize in using tetrabutylammonium bromide (TBAB or QBr) as the regenerated catalyst. The first active catalyst 4,4′-di-tetrabutylammonium biphenoxide ((C 4 H 9 ) 4 N + –OC 6 H 4 C 6 H 4 O −2 –N + (C 4 H 9 ) 4 , QO(Ph) 2 OQ), could be identified, whereas the second active catalyst p -(tetrabutylammonium phenoxy) alkanoxy benzene ((C 4 H 9 ) 4 N + –OC 6 H 4 C 6 H 4 O −2 –C 2 H 5 , QO(Ph) 2 OR) was not detected during the reaction. The first apparent constant of the organic phase reaction was obtained via experimental data. Effect of agitation, temperature, amount of water, organic solvents, catalysts, amount of TBAHS catalyst, amount of sodium hydroxide and volume of alkaline solution on the reaction rate and the conversion were investigated in detail. The results were explained satisfactorily by considering the interaction between the reactants and the environmental species.

A reaction of dibromo-o-xylene and 1-butanol to synthesize diether compound was carried out under two-phase phase-transfer catalysis (PTC) conditions. Mono-bromo-substituted product (o-bromomethyl 1-butanoxymethyl benzene) and dibromo-substituted product (o-di(1-butanoxymethyl)benzene) are both produced from the reaction. Rational reaction mechanism and kinetic model were built up by considering the reaction in aqueous and organic phase, the mass transfer of catalysts between two phases and the phase equilibrium of the catalysts between two phases. The concentration of the active catalyst, identified by instruments, was measured during the reaction. The two apparent rate constants and the two intrinsic rate constants in the organic phase were both obtained via experimental data and the technique of the parameter estimation. Effects of agitation, amount of water, catalysts, amount of tetrabutylammonium bromide (TBAB) catalyst, amount of potassium hydroxide, organic solvents and the temperature on the conversion and the rate constants were investigated in detail. The results are explained satisfactorily of the interaction between the reactants and the environmental species.