Degradation of VOCs by phototcatalytic oxidation reactor using TiO2 pellets

Volatile Organic Compounds (VOCs) are air pollutants that come from burning fossil fuels and industrial emissions. They have potentially adverse health effects being carcinogenic and highly persistent in the environment. The use of photocatalytic oxidation to remove VOCs has the potential to be applied in indoor air quality improvement and industrial emission control. A fixed bed photocatalytic reactor was designed and built. UV black light lamps were installed in the reactor to provide a source of UV radiation. A non-film titania media as pellets were placed on the three fixed beds within the reactor. Toluene and acetone were used as indicators of VOCs during the experiment. With a flow rate of 12.75l/min, the oxidation efficiencies were obtained at four different concentrations of acetone laden gas streams ranging from 40ppm to 250ppm. It was found that the lower the acetone concentration of the untreated inlet gas, the higher the oxidation efficiency. The oxidation efficiency was in the range of 40–70% for various concentrations of untreated gases. Two concentrations of toluene laden gas stream were also tested using the same reactor. The oxidation efficiencies were found as 50% for 120ppm toluene gas and 45% for 300ppm toluene gas. It was found that the times required for toluene to reach oxidization equilibrium have been halved than for acetone gas stream. Other parameters such as flow rate and UV intensity were also altered to see their effects on the oxidation efficiency. A full spectrum scan was carried out using a Bio-rad Infrared spectrometer. It was found that the main components of the treated gas stream from the outlet of the reactor were CO2 and water along with small amount of untreated acetone. The suspected intermediates of aliphatic hydrocarbons and CO were found in very minimal amounts or undetectable. The research experiments supported that the TiO2 pellets can work effectively in a fixed bed photocatalytic reactor and achieve significant oxidation efficiencies for degradation of toluene and acetone as indicators of VOCs.

Highly stable external short-circuit-assisted oxygen ionic transport membrane reactor for carbon dioxide reduction coupled with methane partial oxidation

A membrane reactor allows for simultaneous separation and reaction, and thus, can play a good role to produce value-added chemicals. In this work, we demonstrated such a membrane reactor based on fluorite oxide samarium-doped ceria (SDC) using an external short-circuit concept for oxygen permeation. The fluorite phase was employed to impart its high structural stability, while its limited electronic conductivity was overcome by the application of an external short circuit to function the SDC membrane for oxygen transport. On one side of the membrane, i.e., feed side, carbon dioxide decomposition into carbon monoxide and oxygen was carried out with the aid of a Pt or Ag catalyst. The resultant oxygen was concurrently depleted on the membrane surface and transported to the other side of the membrane, favorably shifting this equilibrium-limited reaction to the product side. The transported oxygen on the permeate side with the aid of a GdNi/Al2O3 catalyst was then consumed by the reaction with methane to form syngas, i.e., carbon monoxide and hydrogen. As such, the required driving force for gas transport through the membrane can be sustained by coupling two different reactions in one membrane reactor, whose stability to withstand these different gases at high temperatures is attained in this paper. We also examined the effect of the membrane thickness, oxygen ionic transport rate, and CO2 and CH4 flow rates to the membrane reactor performance. More importantly, here, we proved the feasibility of a highly stable membrane reactor based on an external short circuit as evidenced by achieving the constant performance in CO selectivity, CH4 conversion, CO2 conversion, and O2 flux during 100 h of operation and unaltered membrane structure after this operation together with the coking resistance.

Photocatalytic decolorization of lanasol blue CE dye solution using a flat-plate reactor

This paper reports the effectiveness of the photocatalysis TiO₂ in degrading Lanasol Blue CE. A flat-plate reactor (FPR) with a reactor area of 0.37 m² and ultraviolet (UV) light source of six 36 W blacklight lamps was used in the study. Operating variables including dosage of the photocatalyst, flow rates through the FPR, UV intensity, and tilted angle of the reactor were investigated to degrade Lanasol Blue CE. Results showed that the photocatalytic process can efficiently remove the color in textile dyeing effluent. The degradation process was approximated using first-order kinetics. The photocatalytic apparent reaction rate increased with the increasing UV intensity received by the photocatalyst TiO₂ in slurry. The liquid flow rate and tilted angle influenced the film thickness. The apparent reaction rate constant was mainly determined by the liquid film thickness, UV intensity, and the dosage of the photocatalyst. The findings of this research can be utilized as preliminary input for potential solar photocatalytic applications on color removal from dye solutions.

Photocatalytic degradation of dyes in wastewater using TiO2/UV in a flat-plate reactor

The photocatalyst TiO₂ with UV irradiation was used to degrade dyes in textile effluent in a flat-plate photoreactor. A test system was built with the reactor area of 1 x 0.3m2, UV light of six 36W-blacklight. TiO₂ powder P25 with BET surface area 50±15m2/g, average primary particle size 21 nm, purity> 99.5% and content of 83.9% anatase and 16.1 % rutile was used as the photocatalyst. A number of dyes commonly present in dyeing wastewater were tested in this study. The different operating parameters, such as dosage of photocatalyst, the structure of the reactor, flow rates through the flat-plate reactor, UV radiation intensity and tilted angle of the reactor, were investigated. The results showed that the photocatalytic process could efficiently remove most of the colour contained in the dyeing wastewater. It was experimentally observed that first-order kinetics was adequate for characterising the process. The flow rate and the tilted angle had some influence on the film thickness of the fluid in the reactor and the empirical correlation between the film thickness of the fluid and these two parameters was developed. The photoreaction rate was mainly determined by the film thickness of the fluid on the reactor surface and the dosage of the photocatalyst. Optimum operating parameters of the system were found to be at the film thickness of about 1.4mm and a TiO₂ dosage of 1 gIL. The higher the UV intensity, the faster the reaction rate was. The results of these experiments showed that this method has the great potential for colour removal from wastewater at commercial scale.

To overcome the common difficulty of separating the used TiO₂ suspension after treatment precipitation followed with filtration was used in this study to determine the separation efficiencies. On the other hand, TiO₂ in a small pillar shape was also studied for photocatalytic degradation of textile dye effluent. The pillar pellet was made in Oegussa Company, Germany ranging from 2.5 to 5.3mm long and with a diameter of 3.7mm. It was almost pure TiO₂ (83.2% anatase and 16.8% rutile), with a S-content of <20 ppm and a CI content of the order of 0.1 wt. %. No further elements are present in contents above 0.05 wt.%. The TiO₂ pillars were placed on the flat-plate reactor that was divided by the rectangular slots and irradiated under UV light when the treated solution went through the reactor. Four dyes and their mixtures were tested. The results showed that the photocatalytic process under this configuration efficiently remove the colour from textile dyeing effluent, and pillar shape TiO₂ photocatalyst was not dissolved in water and very easy to be separated from solution, enabling it to be reused many times. The first-order kinetics was adequate for characterising the photocatalytic degradation process and the photocatalytic performance was comparable to TiO₂ powder. It is believed that the TiO₂ pellet would be a preferable form of photocatalyst in applications for textile effluent treatment process, and other wastewater treatment processes.

Solar photocatalytic oxidation (PCO) process with a flat-plate reactor

An experimental rig with a flat-plate solar reactor was built to study the effectiveness of degradation using the reactive methylene blue as sensitive objective. The factors that affect the degradation performance, such as dosages of photocatalyst (Ti0₂), initial concentration of reactive methylene blue, flow rate through the flat-plate reactor, solar UV radiation intensity and decolourising efficiency of the solution, have been investigated. The results showed that the solar PCO process with a Flat-plate Reactor could degrade the methylene blue and decolour in methylene blue solution efficiently.

Solar versus fossil fuels : A net energy analysis of domestic solar hot water systems in Australia

It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions compared to conventional electric and gas hot water systems. Very rarely has the life-cycle energy requirements (including the embodied energy of manufacture) of solar hot water systems been analysed. The extent to which solar hot water systems can save energy compared to conventional electric or gas hot water systems can be shown through a comparative net energy analysis. This method determines the ‘energy payback period’, including consideration of the difference in operational energy savings and energy embodied in the devices relative to a base case. Dr Robert Crawford, Deakin University, Australia presents the results of a net energy analysis that compared solar and conventional hot water systems for a southern (Melbourne) and a northern (Brisbane) Australian climate.

Fuels of the future : the challenge of new fuel types

Landscape disturbances associated with human activities result in many changes in vegetation structure and floristics. These changes include invasion of native vegetation by both introduced and native species, which leads to the development of 'new' vegetation types. These new vegetation types are often associated with greatly increased fuel loads, and increased levels of fire hazard. Two of these 'new' fuel types are dense thickets of woody weeds, such as Coyote Bush (Baccharis pilularis) and swards of exotic grasses with very high fuel loads, such as Buffel Grass (Cenchrus ciliaris) and Para Grass (Urochloa mutica). The 'new' fuel types which can now be recognized have significant implications for the accuracy of fire behaviour prediction and modelling. For example, modelling fire behaviour in areas invaded by exotic grasses in Australia is problematic, as current grassland fire behaviour models do not allow for the input ofthe high fuel loads associated with these invasive grasses. In forest, McArthur Forest Fire Danger Meters may not be appropriate for forests with significant levels of elevated fuels. Two case studies from southeastern Australia are discussed: the invasion of native vegetation in the urban interface by the woody shrub Burgan (Kunzea ericoides) and invasion of native grasslands by Phalaris (Phalaris aquatica).

A prospective examination of children's time spent outdoors, objectively measured physical activity and overweight

Objective: This study aimed to determine whether time spent outdoors was associated with objectively measured physical activity, body mass index (BMI) z-score and overweight in elementary-school aged children, cross-sectionally and prospectively over 3 years.
Methods: Three-year cohort study with data collected during 2001 and 2004. Nineteen randomly selected state elementary schools across Melbourne, Australia. One hundred and eighty eight 5–6-year-old and 360 10–12-year-old children. Baseline parent reports of children’s time spent outdoors during warmer and cooler months, on weekdays and weekends. At baseline and follow-up, children’s moderate and vigorous physical activity (MVPA) was objectively assessed by accelerometry, and BMI zscore and overweight was calculated from measured height and weight.
Results: Cross-sectionally, each additional hour outdoors on weekdays and weekend days during the cooler months was associated with an extra 27 min week^-1 MVPA among older girls, and with an extra 20 min week^-1 MVPA among older boys. Longitudinally, more time outdoors on weekends predicted higher MVPA on weekends among older girls and boys (5 min week^-1). The prevalence of overweight among older children at follow-up was 27–41% lower among those spending more time outdoors at baseline.
Conclusion: Encouraging 10–12-year-old children to spend more time outdoors may be an effective strategy for increasing physical activity and preventing increases in overweight and obesity. Intervention research investigating the effect of increasing time outdoors on children’s physical activity and overweight is warranted.

Development of a stable continuous flow immobilized enzyme reactor for the hydrolysis of inulin

A 23.5-fold purified exoinulinase with a specific activity of 413 IU/mg and covalently immobilized on Duolite A568 has been used for the development of a continuous flow immobilized enzyme reactor for the hydrolysis of inulin. In a packed bed reactor containing 72 IU of exoinulinase from Kluyveromyces marxianus YS-1, inulin solution (5%, pH 5.5) with a flow rate of 4 mL/h was completely hydrolyzed at 55 °C. The reactor was run continuously for 75 days and its experimental half-life was 72 days under the optimized operational conditions. The volumetric productivity and fructose yield of the reactor were 44.5 g reducing sugars/L/h and 53.3 g/L, respectively. The hydrolyzed product was a mixture of fructose (95.8%) and glucose (4.2%) having an average fructose/glucose ratio of 24. An attempt has also been made to substitute pure inulin with raw Asparagus racemosus inulin to determine the operational stability of the developed reactor. The system remained operational only for 11 days, where 85.9% hydrolysis of raw inulin was achieved.

The impact of using a pedometer on time spent walking in older adults with Type 2 diabetes

Purpose

The purpose of this study was to investigate the impact of using a pedometer on time spent walking, in sedentary and overweight adults with type 2 diabetes participating in a coaching intervention. It was hypothesized that participants using a pedometer would spend more time walking than would nonpedometer participants.

Method

A sample of 57 men and women with a mean age of 62 years participated in a randomized controlled trial in a community setting. Participants were allocated to either a pedometer and coaching (intervention) group or a coaching-only (control) group. Coaching for both groups involved education, goal setting, and supportive/ motivational strategies to increase time spent walking. The duration of the study was 6 months, with blood pressure, glycosylated hemoglobin, anthropometric, and fitness measurements assessed at baseline and at 3-month intervals.

Results

A repeated-measures analysis of variance indicated that the coaching-only group spent significantly more time walking than did the pedometer group. However, when an analysis of covariance with all the other variables as covariates was performed, group membership had no influence on time spent walking. Significant reductions in waist circumference and weight were achieved for both groups from baseline to 6 months. Cardiovascular fitness also increased significantly for both groups.

Conclusion

The study demonstrated that previously sedentary older adults with type 2 diabetes, supported with a coaching intervention, were able to achieve the physical activity targets known to be beneficial to health. However, using a pedometer added no further benefit. Further research on the impact of specific coaching strategies in diabetes management is warranted.

Predictors of time spent outdoors among children : 5-year longitudinal findings

Background Given the importance of physical activity for health and age-related declines in physical activity, understanding influences on related behaviours, such as time outdoors, is crucial. This study aimed to understand individual, social and physical environmental influences on longitudinal changes in urban children’s time outdoors.

Methods The time children spent outdoors in 2001, 2004 and 2006 (aged 5e6 and 10e12 years at baseline) was reported by their parents (n¼421). In 2001, individual, social and physical environmental factors were self-reported by parents. Generalized estimating equations examined longitudinal relationships between baseline predictors and average change in time outdoors over 5 years.

Results Children’s time outdoors significantly declined over time. “Indoor tendencies” inversely predicted time outdoors among younger and older boys, and younger girls. Social opportunities positively predicted time outdoors among younger boys, while “outdoor tendencies” positively predicted time outdoors among older boys. Parental encouragement for activity positively predicted time outdoors among younger and older girls,while lack of adult supervision for active play outdoors after school inversely predicted time outdoors among older girls and older boys.

Conclusion Individual (indoor and outdoor tendencies) and social factors (social opportunities, parental encouragement and parental supervision) predicted children’s time outdoors over 5 years. Interventions targeting reduced indoor tendencies, increased outdoor play with others, and increased parental encouragement and supervision are warranted.