Influence of Oxygen and Dissolved Inorganic Additives on the Removal of Gaseous Acetylaldehyde by Use of a Wetted‐Wall Corona Discharge Reactor

A cylindrical wetted‐wall corona discharge reactor was used for the removal of acetaldehyde in gas mixtures of N₂ and O₂. Gaseous acetaldehyde was removed from the gas stream by simultaneous absorption and gaseous corona reaction. The acetaldehyde absorbed in water, was decomposed by the aqueous radical, OH, produced by contact of the gas corona with the water film. There is an optimized oxygen concentration for the effective removal. When oxygen coexists in the gas mixture at 5 %, acetaldehyde was effectively removed, resulting in overall sustainable removal of acetaldehyde. However, an increase in oxygen concentration resulted in a decrease in the extent of removal, when the corona current was excessively high. This is due to corona‐induced turbulence broadening the residence time distribution of gas in the reaction zone. The decompositions of absorbed acetaldehyde and TOC in water were obviously affected by the varied oxygen concentrations. Acetaldehyde was not removed in the absence of oxygen. The dissolved inorganic additives, NaOH and HCl, strongly affected the acetaldehyde absorbability into water and subsequently, the decomposition rate of the absorbed acetaldehyde.     

Metal catalysts impregnated on porous media for aqueous phenol decomposition within three-phase fluidized-bed reactor

Performance of metal catalysts to decompose aqueous phenol was experimentally investigated. Comparison of the phenol decomposition rates within three-phase fluidized-bed reactors utilizing only O(3), TiO(2) deposited on silica beads, metal catalyst (Ni or Co) impregnated on mesoporous carbon beads, or O(3) in combination with each catalyst was thoroughly examined. It was found that the use of Co catalyst with the presence of O(3) led to the best removal condition which aqueous phenol was completely decomposed within 10 min (k = 0.1944 min(-1)). In contrast, the use of TiO(2) without O(3) resulted in the worst decomposition of phenol (k = 0.0066 min(-1)). Some intermediate products, such as hydroquinone and catechol, were also detected but their final concentrations were negligibly low.     

Role of Surface Area, Primary Particle Size, and Crystal Phase on Titanium Dioxide Nanoparticle Dispersion Properties

Characterizing nanoparticle dispersions and understanding the effect of parameters that alter dispersion properties are important for both environmental applications and toxicity investigations. The role of particle surface area, primary particle size, and crystal phase on TiO₂ nanoparticle dispersion properties is reported. Hydrodynamic size, zeta potential, and isoelectric point (IEP) of ten laboratory synthesized TiO₂ samples, and one commercial Degussa TiO₂ sample (P25) dispersed in different solutions were characterized. Solution ionic strength and pH affect titania dispersion properties. The effect of monovalent (NaCl) and divalent (MgCl₂) inert electrolytes on dispersion properties was quantified through their contribution to ionic strength. Increasing titania particle surface area resulted in a decrease in solution pH. At fixed pH, increasing the particle surface area enhanced the collision frequency between particles and led to a higher degree of agglomeration. In addition to the synthesis method, TiO₂ isoelectric point was found to be dependent on particle size. As anatase TiO₂ primary particle size increased from 6 nm to 104 nm, its IEP decreased from 6.0 to 3.8 that also results in changes in dispersion zeta potential and hydrodynamic size. In contrast to particle size, TiO₂ nanoparticle IEP was found to be insensitive to particle crystal structure.     

Multimodal Molecular Imaging and Identification of Bacterial Toxins Causing Mushroom Soft Rot and Cavity Disease

Soft rot disease of edible mushrooms leads to rapid degeneration of fungal tissue and thus severely affects farming productivity worldwide. The bacterial mushroom pathogen Burkholderia gladioli pv. agaricicola has been identified as the cause. Yet, little is known about the molecular basis of the infection, the spatial distribution and the biological role of antifungal agents and toxins involved in this infectious disease. We combine genome mining, metabolic profiling, MALDI-Imaging and UV Raman spectroscopy, to detect, identify and visualize a complex of chemical mediators and toxins produced by the pathogen during the infection process, including toxoflavin, caryoynencin, and sinapigladioside. Furthermore, targeted gene knockouts and in vitro assays link antifungal agents to prevalent symptoms of soft rot, mushroom browning, and impaired mycelium growth. Comparisons of related pathogenic, mutualistic and environmental Burkholderia spp. indicate that the arsenal of antifungal agents may have paved the way for ancestral bacteria to colonize niches where frequent, antagonistic interactions with fungi occur. Our findings not only demonstrate the power of label-free, in vivo detection of polyyne virulence factors by Raman imaging, but may also inspire new approaches to disease control.     

Characterization of doped TiO2 nanoparticle dispersions

Nanomaterial suspensions with different dopant types and compositions were investigated to examine their effects on agglomeration through the measurement of hydrodynamic diameter (HD), surface charge, and isoelectric point (IEP). Four different types of nanoparticles, all synthesized by a flame aerosol reactor, were considered for the analysis. The nanoparticles considered were pristine TiO₂, Cu–TiO₂, V–TiO₂, and Pt–TiO₂ with dopant concentrations ranging from 1 to 6 wt%. Measurements were conducted over a broad range of pH (3–11) and ionic strengths (0.001–0.1 M) to understand the roles of pH and ionic strength (IS) on dispersion characteristics. Calculations were made using the classical DLVO theory to explain the agglomeration behavior. The results indicate that dopant addition can change surface charge, hydrodynamic diameter, and shift the IEP to higher or lower pH than pristine TiO₂, depending on the type of dopant and composition. Vanadium and platinum doping shifted the IEP to lower pH values, whereas copper doping shifted it to higher pH values. For each of the nanoparticles considered, pH and IS were found to have significant effects on the surface charge and HD, which were also verified by calculation from DLVO theory.     

Effect of Pt or Pd doping on stability of TiO2 nanoparticle suspension in water

Stability of suspensions of TiO₂ nanoparticles synthesized by the flame aerosol reactor (FLAR) could be altered by doping TiO₂ nanoparticles with Pt, Pd, or Pt–Pd dopants. It was found that doping of TiO₂ with Pd or Pt could contribute to the control of the agglomeration of TiO₂ suspended in water. With the change of doping content, the isoelectric point (IEP) of stable TiO₂ suspension decreased gradually from 5 to 3.6 while the specific surface area was increased from 43.27 to 60.84 m²/g. With pH > 6.0, 2 wt% Pt–Pd/TiO₂ suspension exhibited the lowest agglomeration behavior. The plausible intrinsic structures of Pt, Pd, and Pt–Pd doped TiO₂ nanoparticles were proposed and discussed with respect to their IEP based on the DLVO theory.     

The loss of OSA‐modified starch emulsifier property during the high‐pressure homogeniser and encapsulation of multi‐flavour bergamot oil by spray drying

The encapsulation of bergamot oil by spray drying was investigated by using octenyl succinylated waxy maize starch as wall material and bergamot oil as core. The bergamot oil is majorly composed of d‐limonene, linalool and linalyl acetate. High‐speed and high‐pressure homogenisers were used as major tools of emulsification process. The results indicated that some chemical functional groups were lost during the high‐pressure homogenisation. Moreover, larger emulsion droplet size (5–10 μm) was observed when emulsion passed through high‐pressure homogeniser. Meanwhile, the saturation of carrier solution before preparing the emulsion was also important to produce the encapsulated flavour powder by spray drying. The optimal value of air inlet temperature at 160 °C to give the highest flavour retention and the lowest surface oil content was observed. Furthermore, the retention of linalool after spray drying was higher than 100%. The transformation of each flavour might occur.     

Hydrothermal synthesis of titanate nanoparticle/carbon nanotube hybridized material for dye sensitized solar cell application

With the hydrothermal treatment, titanate nanostructure with distinctively different morphology and surface characteristics was successfully synthesized from commercial rutile titania powder dispersed in accommodating media which were deionized water or NaOH solution. Hybridized materials of titanate nanoparticles and carbon nanotubes (CNT) were also synthesized by the hydrothermal treatment process. Intrinsic interaction of titanate nanoparticles and CNTs could be confirmed by spectroscopic analysis. The synthesized titanate nanoparticle/CNT hybridized material was then employed for fabricating a working electrode of dye-sensitized solar cells (DSSC). Based on experimental results, DSSC fabricated from the hybridized titanate nanoparticles and carbon nanotubes could provide the highest photoconversion efficiency of approximately 3.92%.     

Application of TiO2-coated alumina beads to dielectric barrier discharge-photocatalyst hybrid process for NO and SO2 removals

NO and SO2 removal by dielectric barrier discharge-photocatalyst (DBD-P) hybrid process was examined for various conditions of process variables. Alumina beads were coated with TiO2 thin film by a rotating cylindrical PCVD reactor and they were packed inside the cylindrical reactor. The NO and SO2 removal efficiencies can be enhanced by using a combination of dielectric barrier discharge and photodegradation by TiO2. The stronger the applied voltage is, the higher the pulse frequency is, or the longer the gas residence time is, the higher the NO and SO2 removal efficiencies become. By applying additional photocatalytic effect, NO removal efficiency increased more significantly than SO2 removal efficiency, because SO2 removal efficiency was already high by dielectric barrier discharge only. In this study, we found that the alumina beads coated with TiO2 thin film by a rotating cylindrical PCVD reactor could be used effectively to remove NO and SO2 by DBD-P hybrid process.     

Temperature Effect on Removal of Sulfur Dioxide and Benzene in Humid Air by DC Corona Discharge

A DC corona discharge reactor was applied to remove sulfur dioxide (SO₂) and benzene (C₆H₆) from N₂‐O₂‐H₂O mixed gas in the temperature range from room temperature to 400 °C. When SO₂ was removed, the temperature elevation caused the decrease of the removal efficiency of SO₂. On the other hand, the removal efficiency of C₆H₆ was not significantly influenced by the temperature elevation. In the simultaneous removal of SO₂ and C₆H₆ in the relatively low temperature range below 200 °C, the removal efficiency of SO₂ is significantly inhibited by coexisting C₆H₆. When the simultaneous removal was conducted in the high temperature range, the removal efficiency of SO₂ was not sensitive against the coexisting C₆H₆. On the other hand, the removal efficiency of C₆H₆ was almost independent of coexisting SO₂ at all temperatures. A hypothesis of reaction mechanism was discussed based on radical reactions with SO₂ and C₆H₆ to explain the trend observed in the experiment.