Surface Area For Mass Transfer Research Articles

Cleaning Oily Sludge Using Colloidal Gas Aphrons: Optimizing Process Conditions and Analyzing Mechanisms.

Colloidal gas aphrons (CGAs) are applied in pollutant removal due to their large specific surface area and high surface activity. The structure and properties of the prepared CGAs were investigated in the process of oil removal from oily sludge. The prepared CGAs had a liquid film thickness was 5-10 μm with high stability. CGA interfacial tension was as low as 3.157 mN/m. Then it was found that the oil removal rate of CGAs was higher than that of chemical treatments, showing that CGAs could increase the mass transfer surface area and provide additional attachment sites for pollutants, enhancing the oil removal. The treatment conditions of the oil removal were optimized through response surfaces, showing that under optimal treatment conditions, the oil removal rate of oily sludge reached 96.07%. Additionally, the interaction between surfactant concentration and temperature was the most significant of all of the influencing factors. The behavior and mechanism of CGAs in the cleaning process of oily sludge were further investigated using an inverted fluorescence microscope, SEM, FTIR, and two-dimensional fluorescence spectrometer, showing that pollutants transferred from the liquid film surface of CGAs to the inside the film, and CGAs could specifically adsorb negatively charged organic compounds and aromatic hydrocarbons. The results show that CGAs achieved liquid membrane solubilization. Many negatively charged organic compounds and aromatic hydrocarbons are adsorbed onto the CGAs liquid membrane surface via electrostatic and hydrophobic interactions and then migrated to the hydrophobic layer of the CGAs liquid membrane due to the distribution effect, thus enabling rapid pollutant migration between solid and liquid phases.

Expressing variable mass transfer coefficients for gas fermentation in trickle bed reactor

Gasification of lignocellulosic biomass and syngas biomethanation are promising technologies for producing biomethane. Trickle bed reactors (TBR) are efficient for syngas fermentation allowing for higher concentration of microbial cells and high surface area for mass transfer. Optimized scaling up and dimensioning of the reactor is crucial when it comes to industrial applications. The first step towards this goal and the scope of the present study is to develop a model able to simulate the mass transfer of gases to the liquid phase as a function of the operating conditions and reactor geometry. Experiments were performed in a lab scale TBR with co-current flow of syngas and water, representing the growth medium, to determine the volumetric mass transfer coefficient (kLa) of each gas compound and its dependence on the flowrate of syngas and water and reactor structural characteristics. The kLa achieved were in the range of 6.18–13.6 hr−1 for H2, 2.6–5.79 hr−1 for CO and 1.53–3.43 hr−1 for CO2. A dimensionless equation was fitted to the experimental data and a model was developed to predict kLa of a specific gas at various gas and liquid flowrates, and reactor configurations. A kinetic model was also developed to simulate the concentrations of syngas in gas phase and liquid phase by applying the kLa values predicted by the dimensionless correlation. Finally, the model was validated using experimental data obtained by mass transfer coefficient determination in pilot scale TBR with pure argon gas and literature data where the predicted kLa had a coefficient of variance of ± 15% and ± 25% respectively within a realistic range of liquid and gas flowrates.

Advancing aerobic digestion efficiency using ultrafine bubbles in wastewater treatment

The application of ultrafine/nanobubbles (NBs) was tested as an aeration mechanism in a laboratory scale, semi-batch, biological wastewater treatment unit and compared with a similar scale, conventional bubbling supported aerobic digestion unit. The results showed that the oxygen utilization rate (OUR) and volumetric oxygen mass transfer coefficient (kla) were doubled from 0.075 to 0.159 mg O2/min and 0.07 to 0.13 respectively, through the application of NBs compared to the use of conventional bubbles (CBs). This was achieved by exploiting the sufficient residence time NBs can have in the aqueous system along with its capacity of high mass transfer surface area to volume ratio. The twofold increment in the OUR and kla due to the application NBs improved the biodegradation rate of the organic matter from 5.83 to 17.5 mg/l.hr compared to the application of CBs. Thus, 60 % of the hydraulic residence time reduction was achieved by the application NBs compared to CBs to achieve a similar amount of organic waste degradation. Moreover, the membrane filtration results also showed a reduction in the sludge load and fouling rate for aerobic membrane bioreactors supported by NB systems. A possible mechanism for sludge reduction was also proposed based on the results achieved.

Effects of the Broken Kernel on Heat and Moisture Transfer in Fixed-Bed Corn Drying Using Particle-Resolved CFD Model

To investigate the pore structure distribution and the coupled heat and moisture transfer during the drying process of the grains, this study focuses on fixed-bed corn drying with varying levels of broken kernel rate. A model of internal flow and conjugate heat and mass transfer was established for the drying process. Random packing models of whole and half corn kernels with different proportions were generated using rigid body dynamics (RBD), and the porosity, airflow distribution, and coupling of temperature and moisture transfer in fixed beds with different levels of broken kernel rate were analyzed. A fixed-bed corn drying device was developed, and the effects of broken particle contents of 0%, 10%, 20%, and 30% on drying characteristics were studied. The research findings reveal that the radial porosity in the fixed bed exhibits an oscillating distribution, with the localized porosity decreasing as the broken kernel rate increases. Increasing the broken kernel rate intensifies the curvature of the airflow paths within the fixed bed, increasing the pressure drop in the bed. The broken kernels fill the gaps between the whole kernels, improving the uniformity of the velocity distribution within the fixed bed. Under various packing models, the average discrepancy between pressure drop obtained from Particle-resolved Computational Fluid Dynamics (PRCFD) simulations with experimental remains below 15%. The increase in broken kernel rate within the fixed bed enlarges the heat transfer area, resulting in an elevation of the transient heat transfer characteristic parameters during drying. Simultaneously, the broken kernel rate increases the surface area of mass transfer, thereby enhancing the moisture transfer rate within the fixed bed. Compared to the fixed bed without broken kernels (0%), which requires 560 min to dry the corn pile to a safe moisture of 14% (d.b.), the drying time is reduced by 60 min, 100 min, and 130 min for the respective broken kernel contents of 10%, 20%, and 30%, respectively. The PRCFD method successfully simulates the processes of convective heat and mass transfer in the fluid phase and thermal and mass diffusion in the solid phase, exhibiting a strong correlation with experimental data.

Influence of design and operating parameters for additively manufactured intensified packing devices on CO2-Absorption column cooling and capture efficiency

Solvent-based CO2 absorption is technologically a matured CO2 capture pathway but suffers from: high regeneration energy demand, and solvent temperature rise and decreased capture efficiency caused by the heat of reaction. While research has focused on developing non-aqueous and low-aqueous solvents for decreasing the regeneration energy, the temperature bulge due to exothermic absorption is typically dealt with by cooling the solvent with an external inter-stage heat-exchanger. This approach may increase the overall process footprint, as well as capital and operating costs. The current study explores a process intensification approach by incorporating inside the column an additively manufactured intensified packing device that consists of corrugated plates and internal coolant channels. The corrugated plates provide surface area for mass transfer between gas and liquid, while cooling fluid inside the internal channels removes heat from the exothermic reactive system. Two different intensified devices with specific surface areas of 266 m2/m3 and 359 m2/m3 were designed, manufactured, and tested inside a 2.06-m long and 0.203-m diameter column packed with commercial Mellapak 250Y packing. The device with a lower surface area showed up to 27 % reduction in cooling performance. A steady-state heat transfer model provides good agreement with the experimental column temperature and intra-stage heat removal data. Although a decrease in heat transfer performance was observed for the device with lower surface area, CO2 capture experiments performed with simulated flue gas and low-aqueous solvent demonstrated that both intensified devices lead to a similar improvement of 12 % in capture efficiency. This study provides an understanding on simplifying the intensified packing device geometry and decreasing the device fabrication cost by 25 % without compromising with the CO2 absorption performance of the packed column.

Effects of chemical potential differences on methane hydrate formation kinetics

To underpin the increasing interest in practical applications of gas hydrates, for gas storage and separation for instance, the formation and growth of hydrates at liquid-gas interfaces are of fundamental importance. Although the thermodynamics of hydrate formation has been widely studied and is well understood, the kinetics of these processes is not well characterised. In this work, a high-pressure, low-temperature stirred reactor was used to conduct hydrate formation kinetic studies in a temperature range from 276.5 to 283.5 K and a pressure range from 5 to 10.5 MPa, with a special focus on 1) the impact of agitation conditions on the available water-gas interfacial surface area for mass transfer and growth rate during hydrate formation, and 2) the effect of the chemical potential driving force on the formation rate. Five hydrate growth regimes were identified, with varying degrees of gas mass transfer control across the gas-water interface depending on the extent to which hydrate layers built up at this interface, gas needed to move through solid hydrate layers, and the extent to which the gas was entrained within the water phase. The formation rate in the initial linear growth regime, before the onset of solid hydrate gas mass transfer effects, was found to depend in an essentially exponential manner on the chemical potential difference from the equilibrium state. Semi-empirical models related to Arrhenius-type kinetic models were used to correlate the data, the best of which reproduced the formation rates from the chemical potential differences to within ± 5 %. The approach has general applicability to help determine the balance between kinetic and thermodynamic factors in identifying the optimum pressure-temperature conditions for processes for gas storage, gas separation and other hydrate applications.

THE INFLUENCE OF DIFFERENT FACTORS ON THE MAISOTSENKO CYCLE EFFECTIVENESS

An important problem in the heat industry is the significant cost of energy resources for air conditioning. Therefore, energy-efficient refrigeration systems based on renewable energy sources and evaporative air cooling, as well as air-conditioning systems according to the Maisotsenko cycle using psychrometric energy of the environment are of great importance. This paper presents the results of experimental and numerical research of the influence of various factors on the efficiency of indirect evaporative heat and mass transfer apparatus on the M-cycle on the basis of a new unit cell.
 An experimental stand of a heat and mass transfer apparatus with vertically arranged plate channels was developed for experimental research. Experimental studies of heat and mass transfer in the new unit cell were conducted in a wide range of Reynolds numbers 200…1200, temperature 16… 30 °С, relative humidity 30… 50 %. The calculated study was performed using a modified ε-NTU method. Studies have shown that the thermodynamic efficiency of a wet bulb thermometer at a Reynolds number below 500 exceeded one. According to the results of computational studies, the influence of cell length and surface intensification of dry channels on thermodynamic efficiency was determined. Shown the effect of changes in thermodynamic efficiency in the range of 86…94 % increase in efficiency by 1 % leads to an increase in cell length by 7 %. The value of the enhancement factor increases with increasing air flow regime, so when the heat and mass transfer surface area increases by 50 % and the Reynolds number 200, the thermodynamic efficiency increases by 14 %, and with the Reynolds number 800 – by 28 %. The dependence of the thermodynamic efficiency of the cells at the dew point on the relative humidity of the inlet air have a maximum, which with increasing Reynolds number shifts toward larger values of relative humidity.
 Unlike traditional air conditioning devices, the M-cycle heat and mass exchanger does not use a steam compression cycle, so energy costs are spent only on the operation of the fan to pump air, which is a more environmentally friendly and energy efficient way of air conditioning.

CO2 sequestration using a novel Belt Conveyor Reactor with rotating sieve trays compared with Airlift Bubble Column as photobioreactors

The present work aims to evaluate the performance of a novel three-phase reactor Belt Conveyor Reactor BCR (with rotating sieve trays patent GB2567340B) as a photobioreactor compared with a traditional Airlift Bubble Column ALR, both influenced by the flow of the gas. Chlorella vulgaris was cultivated in these two photobioreactors using ambient air has a CO2 concentration of 0.038% with different aeration flowrates 0.145, 0.195, 0.24, and 0.29 vvm (gas volume per minute/liquid volume in the reactor).The maximum growth rate achieved on the 14th day of culture was 2.120 and 1.420 g/L for BCR, ALR respectively, with initial biomass concentrations of 0.2 g/L and aeration flow of 0.29 vvm. Moreover, the removal efficiency of carbon dioxide sequestration by the two photobioreactors is 40% for BCR and 25% for ALR. The innovative design succeeded in operational quality of agitation with high gas holdup inside the sieve trays to increase the biomass growth up to 50% higher than in the ALR. The maximum CO2 fixation for ALR was at about 18% at a specific aeration rate of 0.145 vvm in the bubbly regime. Whereas in the BCR can be reached about 38% with wide range operation condition of airflow rate 0.145–0.24 vvm due to well-distributed liquid due to rotating trays, and good gas–liquid mass transfer surface area.

Green methane production: Kinetic and mass transfer modeling in a batch process

One of the major issues in biomethanation studies, especially a batch strategy without mixing, is gaseous substrate mass transfer between gas and liquid phases. The strategy can be assumed as a simplified form of a stagnant underground gas reservoir. Hydrogen gas, as the limiting substrate, plays significant role in biomethanation. Being informed of hydrogen content diffused within the liquid phase for calculating percentage of active volume, help researcher to make a proper decision on bioreactor design or adjusting process parameters. For this purpose, a mass transfer modelling was developed which strengthened with a set of optimized biokinetic parameters. Parameter optimization was accomplished with the help of a predefined optimization algorithm and using a set of experimental data with the source of literature. Active volume calculation was successfully performed via the verified model and response surface methodology was served for maximizing it under variety of process conditions. It was found that the bioreactor height to width ratio significantly affected on active volume followed by pressure and temperature. In addition, working with a bioreactor with a circle cross section, in comparison with a square one, improved the maximum active volume up to 43% due to providing higher surface area for mass transfer. Sensitivity analysis verified the previous findings and revealed that higher pressures and temperatures linearly increased the active volume while increasing the bioreactor height to width ratio exponentially decreased the response. Furthermore, a wide bioreactor have potential to promote active volume up to 72% rather than a vertical one.

Visible-light-driven photo-Fenton reactions using Zn1-1.5xFexS/g-C3N4 photocatalyst: Degradation kinetics and mechanisms analysis

The visible-light responsive hybrid catalysts (Zn0.94Fe0.04S/g-C3N4 or ZCN) were synthesized by a rapid microwave hydrothermal method. Our results showed that the deposition of Fe-doped ZnS onto g-C3N4 sheets prevented the aggregation of Zn0.94Fe0.04S and increased the surface area for mass transfer and light absorption. The highest degradation rate of p-nitrophenol (PNP) was 96.0% and the total organic carbon removal rate was 55.4% after 60-min simulated solar light irradiation on ZCN with Fe doping and g-C3N4 loading ratios of 0.04 and 0.20, respectively. Hydroxyl radical played a dominant role in PNP degradation, which was primarily attributed to the photo-Fenton reactions. The PNP degradation pathway involved denitration and hydroxylation reactions according to the Density Function Theory calculations and HPLC-MS/MS results. The QSAR analysis indicated that the toxicity of most intermediates was lower than PNP. This study develops novel materials with superior photocatalytic activity for elimination of refractory organic pollutants in wastewater.

3D simulation of transport phenomena of onion drying with moving boundary in a vacuum oven

AbstractThis study aimed to perform numerical simulation of the onion drying process considering its deformed geometry. For this purpose, transport phenomena such as heat and mass transfer in the onion structure and water vapor transfer in its porous structure were simulated in 3D form with Darcy's law during the vacuum drying process for onions. The simulated results were validated by experimental data. Heat and mass transfer rates were determined using kinetic data. Simulation of onion drying revealed that deformed geometry should be included in the model to represent the faster removal of water from the onion due to the increase in mass transfer surface area. The influence of drying temperature (313, 323, 333, and 343 K) on drying time and water concentration of onion was insignificant. The mass transfer Biot number revealed that the water vapor removal from onion was controlled by intraparticle mass transfer resistance.Practical applicationsThe main purpose of the vegetable drying industry is to obtain good‐quality dried products accompanied by savings in terms of energy and time. Recently, heat and mass transfer models constructed for drying of vegetables have focused on vegetables such as potato or carrot that provide limited information due to their uniform structure. An onion slice has a porous structure and increasing spaces between its rings; therefore in this study, heat and mass transfer occurring during vacuum drying of an onion was simulated considering the deformed geometry. The analysis of transport phenomenon mechanisms involves valuable information for researchers studying drying of food and large‐scale vacuum dryer designers in which 3D simulation of onion drying revealed that the deformed geometry fitted better to experimental results than undeformed geometry. The results of 3D simulation can be used to predict drying time and energy requirements of the process better than regular numerical modeling and may serve dried onion manufacturers.

Experimental study on the droplet formation around pins of different geometry for the design of a compact falling-droplet absorber

Absorber downsizing for the development of compact absorption chillers is a known challenge of this type of refrigerator. Past studies have revealed how a droplet flow regime can increase the interface area and enhance absorption rates, especially during the droplet formation. This study proposes a space-efficient design for an adiabatic absorber based on a bank of solid pins coupled with a droplet flow regime. Manufacturing through 3D printing technique is used to study the effect of different fin shapes during droplet formation. Droplet behavior is firstly studied analytically through a variational approach. Experiments on pure water are then carried out to validate the model and produce design guidelines for a H2O-LiBr absorber. Results show that the analytical model is more accurate in the regions close to the droplet bottom. The rhomboidal geometry with 120° returned the smallest droplet volume without allowing coalescence of more droplets, ensuring the maintenance of droplet flow and a high surface area for mass transfer. Disturbances in the droplet profiles were observed, caused by the pin-droplet interaction. A map has been then created to allow a quick sizing of the absorber and find its main geometrical and operational features.

Predicting Dispersion and Pollutant Concentration of Dimethyl Sulfide (DMS) from a Biofilter Under Various Atmospheric Conditions

Meat rendering plants convert waste animal materials into value added products. During the conversion process, several highly odorous compounds such as ammonia, ethylamines, hydrogen sulfide, dimethyl sulfide, and methyl mercaptan are released into the atmosphere. Due to odorous nature, these compounds cause nuisance to the community who live in the neighborhood of the meat rendering plant; thus, plant received regular odor complaints. Although installation of gas-phase biofilters alleviates the problem of odor complaints, the successful operation of a biofilter depends on many parameters such as maintaining optimum moisture content of the biofilter media, sufficient empty bed residence time (EBRT), high surface area for mass transfer, acceptable mechanical resistance to avoid bed compaction, and good environment for bacterial growth. Deficiencies in the operational parameters of a biofilter can lead to high level of pollutant release into the environment. In this work, dispersion of pollutants that are released from an industrial biofilter, installed in Ontario, Canada, is investigated. Dispersion model CALPUFF was used to predict pollutant concentrations and dispersion under various atmospheric conditions. Influence of wind directions, plume paths, atmospheric conditions, and removal efficiency of the biofilter are investigated.

Scalable Production and Cryostorage of Organoids Using Core–Shell Decoupled Hydrogel Capsules

Organoids, organ-mimicking multicellular structures derived from pluripotent stem cells or organ progenitors, have recently emerged as an important system for both studies of stem cell biology and development of potential therapeutics; however, a large-scale culture of organoids and cryopreservation for whole organoids, a prerequisite for their industrial and clinical applications, has remained a challenge. Current organoid culture systems relying on embedding the stem or progenitor cells in bulk extracellular matrix (ECM) hydrogels (e.g., Matrigel™) have limited surface area for mass transfer and are not suitable for large-scale productions. Here, we demonstrate a capsule-based, scalable organoid production and cryopreservation platform. The capsules have a core-shell structure where the core consists of Matrigel™ that supports the growth of organoids, and the alginate shell form robust spherical capsules, enabling suspension culture in stirred bioreactors. Compared with conventional, bulk ECM hydrogels, the capsules, which could be produced continuously by a two-fluidic electrostatic co-spraying method, provided better mass transfer through both diffusion and convection. The core-shell structure of the capsules also leads to better cell recovery after cryopreservation of organoids probably through prevention of intracellular ice formation.

3D nickel-cobalt diselenide nanonetwork for highly efficient oxygen evolution

Active, stable and low-cost oxygen evolution reaction (OER) catalyst for electrochemical water splitting is key to efficient energy conversion and storage. Here, we report a three-dimensional (3D) nanonetwork as noble-metal-free electrode consisting of nickel cobalt diselenide (NiCoSe2) nanobrush arrays on Ni foam (NF) through the initial hydrothermal reaction and subsequent thermal selenization process. Introducing ammonium fluoride as surface controller, different NiCoSe2 hierarchical architecture can be modulated from nanorods, nanobrush to nanosheets. The unique brush-like NiCoSe2 possesses high surface area for mass transfer, rough surface with rich active sites, 3D nanostructure preventing the accumulation of O2 bubbles. Compared to NiCoSe2 nanorods/NF, NiCoSe2 nanosheets/NF and commercial RuO2, NiCoSe2 nanobrush/NF exhibits an enhanced OER performance in alkaline media to reach a low overpotential of 274mV at the current density of 10mA/cm2, small Tafel slope and a long-term stability. The developed 3D nanonetwork highlights the nanoscale engineering and offers a promising alternative to noble metal catalysts for electrochemical water oxidation.

Dramatic effect of residual gas on dynamics of isobaric adsorption stage of an adsorptive chiller

This paper reports an experimental study aimed to elucidate the effect of non-adsorbable gases (air and hydrogen) on dynamics of isobaric adsorption stage of an adsorptive chiller (AC) cycle. This is the first study performed on real small scale adsorbers, based on commercial heat exchangers (HExs) filled with loose grains of the adsorbent AQSOA™-FAM-Z02. The adsorption dynamics was studied by a gravimetric large temperature jump method under conditions of typical AC cycle. Three notable observations are described in the paper: (1) at any gas pressure Pgas, the experimental uptake curves are exponential; (2) the adsorption rate is extremely sensitive to traces of residual air and depends on the HEx geometry and the nature of residual gas; (3) the effect of hydrogen is less dramatic as compared with air. The minimal amount of residual air necessary to form the blocking air-rich layer is evaluated by developing a one-dimensional stationary model of the vapour adsorption in the presence of gas. This amount is found to be highly sensitive to the total vapour pressure and the HEx mass transfer surface area. Practical recommendations on avoiding/dumping the effect of residual gas are made.

Experimental and theoretical study of fluidized bed for SO 2 recovery as sulfur from effluent gases from sulfur production unit

Abstract This paper studies the adsorption process behavior of SO 2 removal in one fluidized bed reactor which is filled with aluminum oxide catalysts. The performance of catalytic bed is analyzed experimentally and theoretically in this work. Sulfur elimination from gas is the major purpose of the handled experiments. The influence of bed height, bed width, diameter of aluminum oxide particles which affects the mass transfer surface area, operating conditions such as temperature and pressure which affects the mass transfer coefficient and rate of reaction and also superficial velocity of inlet gas which affects the residence time are measured and discussed. Results show the increase in the percentage of SO 2 removal with increasing sorbent aluminum content and bed height. The increase in the percentage of SO 2 removal with increase of operating temperature (0.41%), pressure (0.21%), superficial velocity (0.5%), bed diameter (0.16%), bed height (0.58%), and surface area (0.63%) and with decrease of particle diameter (0.54%) are obtained. The applied mathematical model can predict the experimental data with an average accuracy of 92%.

REGULARITIES OF INJECTION PROCESSING OF HOT METAL BY MAGNESIUM INJECTION LANCE WITH A LOT OF NOZZLES

The aim work is to study peculiarities of formation and mass transfer out of lance zones during injection desulphurization in ladles using two- nozzles lances. The experiments were performed on a cold transparent model (1:10) of landle. Varied design lance diameter of channel, angle of deviation nozzles, flow and velocity of the gas. Determined parameters out of lance zone penetration depth flow of conditioned mass transfer surface area, motion parameters baths, etc. worked out rational parameters of magnesium injection for more efficient assimilation of its iron.

Modelling and dynamic simulation of struvite precipitation from source-separated urine

A model of a mixed-mode nutrient recovery reactor is developed for a urine feed, incorporating complex solution thermodynamics, dynamic conservation relations and a power-law kinetic expression for crystal growth from seed crystals. Simulations at nominal operating conditions predict phosphorus recoveries greater than 99%, based on existing process kinetic parameters and operating conditions employed in previously published studies. The overall rate of nutrient recovery depends on the saturation index of the precipitating solid, the available surface area for mass transfer and the feed rate of the limiting constituent ion. Under the conditions considered, the nutrient feed rate appears to be the limiting factor for precipitation. Simulations demonstrate that diurnal feed flow variations of ±50% have a small effect on the rate of nutrient recovery. Overall, the study shows that valuable insights are gained in relation to process performance predictions, which should lead to more confident process design, operation and control.

Solar‐Light‐Driven Photodegradation and Antibacterial Activity of Hierarchical TiO2/ZnO/CuO Material

AbstractInspired by the highly efficient hierarchical structure of plants that use natural light, the hierarchical “forest‐like” TiO2 nanofiber/ZnO nanorod/CuO nanoparticle ternary material 2 is synthesized by a stepwise process: electrospinning of TiO2 nanofibers, hydrothermal growth of ZnO nanorods, and photodeposition of CuO nanoparticles. Material 2 has a higher photodegradation rate of acid orange (AO 7) and stronger antibacterial capability under irradiation with solar light in comparison to that of the hierarchical “tree‐like” TiO2 nanofiber/ZnO nanorod material 1 and one dimensional as‐spun TiO2 nanofibers. These enhancements result from the unique hierarchical forest‐ and tree‐like features of materials 1 and 2, which enhance the light absorption capability, increase the specific surface area for mass transfer and bacteria attachment, create more reaction sites, and retard the recombination of photogenerated electrons and holes. A proportional relationship was found between the photocatalytic activity and the hierarchy of the materials. The sizes of the hierarchical nanostructured materials are in the micron range, which provides the opportunity for using these materials in engineering applications.