Oxygen Production Rate Research Articles

Spatial responses of ecosystem services to carbon emission efficiency based on spatial panel models in the Yangtze River Economic Belt

Enhancing carbon emissions efficiency (CEE) is one of the effective ways to improve ecosystem services (ESs) and achieve sustainable developments. For Yangtze River Economic Belt (YREB), China, achieving better CEE is essential after three decades of developments. This would require an integrated understanding of the relationship between CEE and ESs, which is spatially explicit. This study analyzed multi-source data between 1990 and 2020 in YREB with consideration to the spatial relationships between CEE and total ecosystem services (TES) and the spatial spillover effects of CEE. By adopting a spatial econometrics method, it further analyzed the spatial response mechanism between CEE and TES, which is important for developing sustainable land use strategies and managing ecosystems. The analyses showed that food productivity (FP), carbon sequestration and oxygen production rate (CSOP), water retention (WR), and soil conservation (SC) increased from 1990 to 2020. Moreover, the maldistribution of water systems and the difference in coverage of cultivated land and forestland together led to different spatial distributions of TES in YREB–a high TES cluster in the east and gradual decrease of TES toward the west. CEE throughout the region showed a slight upward trend, with the highest CEE exhibiting a congregated pattern in the middle and lower reaches. The overall spatial correlation between CEE and TES is significantly negative, and CEE has significant spatial spillover effect on TES, meaning that increased CEE in a specific region will lead to degraded TES in neighboring regions, which also presented empirically-supported recommendations for optimizing land use zoning and fostering sustainable development at a regional scale. And the study provides concrete evidence that TES is determined not only by CEE in-situ, but also surrounding regions. Therefore, the spatial negative spillover effects of CEE should be fully considered in the formulation of sustainable development policies, specifically in inter-regional cooperation.

Unveiling novel pathways and key contributors in the nitrogen cycle: Validation of enrichment and taxonomic characterization of oxygenic denitrifying microorganisms in environmental samples

Microorganisms play a crucial role in both the nitrogen cycle and greenhouse gas emissions. A recent discovery has unveiled a new denitrification pathway called oxygenic denitrification, entailing the enzymatic reduction of nitrite to nitric oxide (NO) by a putative nitric oxide dismutase (nod) enzyme. In this study, the presence of the nod gene was detected and subsequently enriched in anaerobic-activated sludge, farmland soil, and paddy soil samples. After 150 days, the enriched samples exhibited significant denitrification, and concomitant oxygen production. The removal efficiency of nitrite ranged from 64.6 % to 79.0 %, while the oxygen production rate was between 15.4 μL/min and 18.6 μL/min when exposed to a sole nitrogen source of 80 mg/L sodium nitrite. Additionally, batch experiments and kinetic analyses revealed the intricate pathways and underlying mechanisms governing the oxygenic denitrification reaction by using CARBOXY-PTIO, 18O-labelled water, and acetylene to unravel the intricacies of the reaction. The quantitative polymerase chain reaction (qPCR) results indicated a significant surge in the abundance of nod genes, escalating from 7.59 to 10.12-fold. Moreover, analysis of 16S ribosomal DNA (rDNA) amplicons revealed Proteobacteria as the dominant phylum and Thauera as the main genus, with the presumed affiliation. In this study, a new nitrogen conversion pathway, oxygenic denitrification, was discovered in environmental samples. This process provides the possibility for the control of nitrous oxide in the treatment of nitrogenous wastewater.

Spectroscopy electrochemical impedance characterization of membranes electrode assemblies for PEM electrolyzers

Abstract Hydrogen is projected as a key energy vector to achieve aspiring global decarbonization goals mainly for those sectors where greenhouse gas emissions are highly challenging to reduce. Therefore, green hydrogen production using water PEM electrolysis has become the aim of numerous recent studies. One of the crucial challenges for improving hydrogen production is reaching a deep knowledge of the role of anodes electrocatalysts. In this investigation we studied and modeled the effect of different anode electrocatalysts and solid electrolyte’s configurations in a single-cell PEM electrolyzer performance, using EIS. We assembled and tested PEM electrolysis MEAs with two different configurations. MEA-1 comprises in catalyst-coated membrane (MEA)-type with a geometric area of 25 cm2 containing Nafion™ 115, 3.0 mg cm−2 IrRuOx as the anode, and 3.0 mg cm−2 PtB for the cathode. MEA-2 involves catalyst-coated membrane (MEA)-type with a geometric area of 25 cm2 containing Nafion™ 117, and 3.0 mg cm−2 PtB both for the anode and cathode. Sintered Ti plates were used as gas diffusion layers. After hydration and activation steps at room temperature, the polarization curve was performed. Hysteresis curves were achieved to provide information on thermal equilibrium during the measurements. The oxygen and hydrogen production rate were measured and compared to theoretical values. Experiments were carried out at 20 and 40 °C. EIS measurements were performed at different points of the polarization curve, sweeping a frequency range between 10 kHz and 10 mHz, with an amplitude of 5 mV and taking 10 points per decade. To avoid electrocatalysts area effects in charge transfer reaction, time constants were calculated. It can be clearly observed the trend of resistances and overpotentials according to different process control. Low onset potential for oxygen evolution reaction depicts for MEA-1 means that there will be less power consumption to achieve the same efficiency or same amount of gas generation rate compared to high onset potential case depicted for MEA-2. Although different membrane thicknesses would result in different electrochemical performances due to the change in the ionic resistance, for the thickness studied we did not observe a change in the ionic resistance. The experimental results show an increase in efficiency with temperature, reflected in higher currents for a given potential and lower time constants resulting in the EIS runs.

Membrane-Targeting Perylenylethynylphenols Inactivate Medically Important Coronaviruses via the Singlet Oxygen Photogeneration Mechanism.

Perylenylethynyl derivatives have been recognized as broad-spectrum antivirals that target the lipid envelope of enveloped viruses. In this study, we present novel perylenylethynylphenols that exhibit nanomolar or submicromolar antiviral activity against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) and feline infectious peritonitis virus (FIPV) in vitro. Perylenylethynylphenols incorporate into viral and cellular membranes and block the entry of the virus into the host cell. Furthermore, these compounds demonstrate an ability to generate singlet oxygen when exposed to visible light. The rate of singlet oxygen production is positively correlated with antiviral activity, confirming that the inhibition of fusion is primarily due to singlet-oxygen-induced damage to the viral envelope. The unique combination of a shape that affords affinity to the lipid bilayer and the capacity to generate singlet oxygen makes perylenylethynylphenols highly effective scaffolds against enveloped viruses. The anticoronaviral activity of perylenylethynylphenols is strictly light-dependent and disappears in the absence of daylight (under red light). Moreover, these compounds exhibit negligible cytotoxicity, highlighting their significant potential for further exploration of the precise antiviral mechanism and the broader scope and limitations of this compound class.

(Keynote) Electrochemistry on Mars – Two Years of MOXIE (Mars Oxygen ISRU Experiment) Operations Producing Oxygen on the Surface of the Red Planet

By the time of the 243rd ECS, NASA’s Mars2020 Perseverance rover will have spent over two Earth years on the surface of Mars, during which time the MOXIE experiment (Mars OXygen ISRU Experiment) will have produced oxygen at night and in the day during both the annual maximum and minimum atmospheric density periods, as well as at many other times during the year. MOXIE is the first demonstration of the use of indigenous resources (ISRU = In Situ Resource Utilization) on the surface of another planet. This talk will explain how MOXIE works and will present a summary of what MOXIE has accomplished, how its performance on Mars has changed with time, and plans for the future. The paper will also present results from an optimization study of a human-scale MOXIE-type system capable of providing the oxidizer for a 6–person Mars Ascent Vehicle. As an experiment carried inside the rover, MOXIE had to satisfy many constraints that would not apply to an independent, full-scale system. Other potential oxygen-producing technologies should be compared to the optimized human-scale system results summarized in this paper rather than to a simple linear scaling of the mass, power consumption, and oxygen production rate of MOXIE.

Analysis of models describing thermocline depth-ocean temperature and dissolved oxygen concentration in the ocean-plankton community

In the present work, the two mathematical models describing components of the climate are examined using the numerical method. The first model depicts the relation between the change in thermocline depth and ocean temperature. The second model is simplified by eliminating the natural depletion of the Phytoplankton population. The stability and convergences analysis is conducted for the modified system. The numerical simulation is conducted with the help of the most proven numerical method, called the Adams Predictor-Corrector method. The effect of the oxygen production rate by Phytoplankton (τ) is illustrated with 2D plots. The graphs of the solutions of the models demonstrate the influence of different parameter values on the solutions. The present investigation helps to work for more complex models, and the model can be examined with novel operators.

18 Months of MOXIE (Mars oxygen ISRU experiment) operations on the surface of Mars - Preparing for human Mars exploration

By the time of the 2022 IAC, NASA's Mars2020 Perseverance rover will have spent 18 months on the surface of Mars, during which time the MOXIE experiment (Mars OXygen ISRU Experiment) will have produced oxygen at night and in the day during both the annual maximum and minimum atmospheric density periods, as well as at many other times during the year. MOXIE is the first demonstration of the use of indigenous resources (ISRU = In Situ Resource Utilization) on the surface of another planet. This paper will present a summary of what MOXIE has accomplished, how its performance on Mars has changed with time, and plans for the future. The paper will also present results from an optimization study of a human-scale MOXIE-type system capable of providing the oxidizer for a 6–person Mars Ascent Vehicle. As an experiment carried inside the rover, MOXIE had to satisfy many constraints that would not apply to an independent, full-scale system. Other potential oxygen-producing technologies should be compared to the optimized human-scale system results summarized in this paper rather than to a simple linear scaling of the mass, power consumption, and oxygen production rate of MOXIE.

Design and assembly of TZCS/PO/Ni2P-MnOx composite with “homojunction + protection layer + cocatalyst” structure for photocatalytic overall water splitting

Herein, we synthesize a phosphate (PO) protection layer and various cocatalysts (Ni2P and MnOx) on the twinned Zn0.5Cd0.5S (TZCS) photocatalyst by a two-step photochemical synthesis method. The initial photocatalytic hydrogen production rate of TZCS/PO/Ni2P-MnOx composite with “homojunction + protection layer + cocatalyst” structure reaches 1.36 mmol h−1 g−1, which is about 1.72 and 2.56 times higher than WZCS/PO/Ni2P-MnOx and ZZCS/PO/Ni2P-MnOx photocatalysts (WZCS and ZZCS are abbreviations of wurtzite Zn0.5Cd0.5S and zinc-blende Zn0.5Cd0.5S solid solutions), respectively. The average photocatalytic hydrogen and oxygen production rate of TZCS/PO/Ni2P-MnOx are 1.21 mmol h−1 g−1 and 0.59 mmol h−1 g−1 within 12 h, which are close to the theoretical ratio of 2: 1. The excellent photocatalytic overall water splitting performance can be rationalized by the separation, transmission and application process of photogenerated electron-hole pairs, which can be efficiently separated and transported by the homojunction structure and further penetrate the PO protection layer, so that they have a greater chance of being captured by the Ni2P and MnOx cocatalysts, which can be used as the active catalytic site for the H2 and O2 production reaction, respectively.

Photophysical Rate Constants and Oxygen Dependence for Si and Ge Rhodamine Zwitterions.

The family of group XIV rhodamine zwitterions are fluorescence probes with carbon, silicon, germanium, or tin substituted in the 10-position of the xanthene ring. Because of their inherent near-infrared fluorescence, photostability and high quantum yields in aqueous solutions, the Si and Ge containing fluorophores in this class have become increasingly important for fluorescent labeling of proteins and biological molecules. This study fully characterizes photophysical rates derived from a model consisting of a singlet ground state, the lowest singlet excited state, and the lowest triplet excited state for two exemplar group XIV rhodamine zwitterions, one containing Si and the other Ge. Within a simple Jablonski diagram, all radiative and non-radiative rates, including intersystem crossing and triplet depopulation rates, were measured as a function of oxygen concentration. It was shown that the triplet depopulation rates are intrinsically fast in comparison with traditional xanthene containing fluorophores, probably due to the increased spin-obit coupling from the Si and Ge substitution in the xanthene ring. Dissolved oxygen increases both the intersystem crossing and triplet depopulation rates. Stern-Volmer analysis was conducted to estimate rates of quenching by oxygen. The experimental data was used to estimate the initial rates for reactive oxygen production by Si and Ge containing fluorophores in aqueous solutions containing different concentrations of dissolved O2. These estimates showed a significantly slower initial rate of reactive oxygen production in comparison with rhodamine 6G. This goes a long way to explaining their inherent photostability. Spectroscopic experiments were also conducted in 77 K viscous aqueous glasses where it was observed that the fluorescence spectra remained unchanged, and the quantum yields increased from 0.53 to 0.84 and from 0.52 to 0.89 for the Si and Ge containing fluorophores respectively; no phosphorescence was observed. All intersystem crossing and triplet depopulation rates were measured using fluorescence correlation spectroscopy (FCS) and analyzed using a new method that extrapolated the power dependence of the FCS curves to optical saturation. This method was verified using published data.

Adapting a Mars ISRU System to the Changing Mars Environment

This study modeled the performance of a full-scale Mars in situ resource utilization (ISRU) system to produce 30 metric tons of liquid O 2 , operated for 14 months at half-hourly intervals as the Mars environment changes diurnally and seasonally. We considered various control options, with particular emphasis on power requirements and required cell voltages. Mars temperature and pressure data at half-hour intervals were obtained from the Mars Perseverance team. The full-scale Mars ISRU system included a mechanical compressor, high-temperature electrolysis of Martian CO 2 , and a liquefier to produce liquid oxygen. The key factors were (a) maintaining cell voltage well below the Nernst potential for carbon formation from CO and (b) tracking the maximum power, as well as the range of power required, at each half-hourly junction across the 14-month run for each control option. The most favorable control option involved adjusting the compressor revolutions per minute at each half-hour to produce a quasi-steady state of oxygen production in the electrolysis and the liquefaction systems, resulting in the most benign electrolysis settings, the lowest maximum power, and the narrowest range of required power. Other approaches where the compressor was run at a steady state and the oxygen production rate varied with time led to higher electrolysis voltage, higher maximum power, and a wider range of power. This study provides guidance on the optimum operating conditions and power requirements of a Mars ISRU system to produce 30 metric tons of liquid oxygen in 14 months of operation.

Oxygen-vacancy-rich Ag/Bi5O7Br nanosheets enable improved photocatalytic NO removal and oxygen evolution under visible light exposure

Photocatalytic NO removal is a green and sustainable alternative to the conventional thermocatalysis in the conversion of NO to nitrates. However, the efficiency of photocatalytic NO removal is restricted by weak NO adsorption and high charge recombination on photocatalyst. Herein, we report on one-step synthesis of Ag/Bi5O7Br nanosheets with rich oxygen vacancies (OVs) by a facile liquid phase reduction method. Under visible light irradiation on oxygen-vacancy-rich Ag/Bi5O7Br for 50 min the photocatalytic NO removal ratio is up to 64.65%, which is about 1.6 times higher than that by using pristine Bi5O7Br. The average oxygen production rate is 823 μmol·g−1·h−1, which is nearly 10 times higher than that of Bi5O7Br. Density functional theory (DFT) calculations reveal that OVs incorporation and plasmonic Ag can synergistically strengthen NO adsorption on Bi5O7Br. This work highlights the great potential of defects and plasmonic metals on synergistic enhancement in photocatalytic NO removal and oxygen evolution.

Environmental constraints on the photosynthetic rate of the marine flatworm Symsagittifera roscoffensis

Symsagittifera roscoffensis, an Acoel flatworm that lives within the intertidal zone, was first discovered over a century ago as a “plant animal” due to its symbiotic relationship with the alga Tetraselmis convolutae. Although commonly used as a model organism in biomedical research, there is little information regarding its life history or how environmental factors affect this organism. In this study, we investigated the effects of a range of abiotic factors on S. roscoffensis by measuring its photosynthetic oxygen production rate under different salinities, temperatures, light intensities, photoperiods, and nutrient concentrations over 6 days. Salinity (20, 30 and 40) had little effect on photosynthetic rate, whereas a temperature of 14 °C yielded significantly higher final oxygen production than 0 and 30 °C. The lowest light intensity (21 μmol m−2 s−1), the shortest photoperiod (8 L:16 D) and the intermediate nutrient concentration (f/4) resulted in the highest final oxygen production rates. Our results showed that S. roscoffensis had the ability to tolerate and remain photosynthetically active under a wide range of conditions that it is likely to experience within the intertidal zone. Using our experimental data, we estimated that S. roscoffensis was able to produce 174% body C d−1 via photosynthesis alone, which could explain the total absence of heterotrophic feeding in this organism. The organism appeared to be robust and easy to cultivate, which should open new opportunities for its wider applications.

Optimized electroless deposition of NiCoP electrocalysts for enhanced water splitting

Great scientific effort has strived to develop a low-cost and sustainable electrocatalyst with high electrocatalytic activity and long-term stability in the field of water splitting. In this work non-noble metal based NiCoP alloys are burgeoned from catalytic Ni substrates via a facile and eco-friendly electroless deposition method under mild conditions. By appropriately tuning the cobalt content in the chemical bath, we realize NiCoP coatings with tailored Co concentration. The electrochemical investigations of coatings deposited on flat Ni indicate an optimal Co content of 17 at % (Ni0.83Co0.17P) to maximize OER performance. Impressively, the Ni0.83Co0.17P coating deposited on nickel foam exhibits remarkable OER catalytic activity (η = 295 mV at 10 mA cm−2), noteworthy catalytic kinetics (Tafel slope as small as 45 mV dec−1) and high rate of oxygen production for each active site (turnover frequency of 0.16 s−1 at 300 mV) in 1 M KOH. Importantly, the Ni0.83Co0.17P/NF demonstrates excellent long-term stability as inferred by continuous test for 25 h. Furthermore, a full alkaline electrolyzer is designed using Ni0.83Co0.17P/NF as the anode and Pt decorated Ni−P/NF as the cathode, which can drive overall water splitting with a potential as low as 1.60 V at 10 mA cm−2, and also shows outstanding long-term durability.The cheapness of the present preparation method as well as its suitability for large-scale production without the need of expensive raw materials and energy-consuming processes paves the way towards commercial production of transition metal phosphide-based electrocatalysts.

Efficient Photocatalytic Hydrogen and Oxygen Evolution by Side-Group Engineered Benzodiimidazole Oligomers with Strong Built-in Electric Fields and Short-Range Crystallinity.

The insufficient charge separation and sluggish exciton transport severely limit the utilization of polymeric photocatalysts. To resolve the above issues, we incorporate bountiful carboxyl substituents within a novel benzodiimidazole oligomer and assemble it into a crystalline semiconductor. The photocatalyst is polar, hydrophilic, short-range crystalline, and capable of both hydrogen and oxygen evolution. The introduction of carboxyl side-groups adds asymmetry to the local structure and increases the built-in electric field. Further, accelerated carrier transfer is enabled via the short-range crystallinity. The superior hydrogen and oxygen production rates of 18.63 and 2.87 mmol g-1 h-1 represent one of the best performances ever reported among dual-functional polymeric photocatalysts. Our work initiates studies on high-performance oligomer photocatalysts, opening a new frontier to produce solar fuel.

Efficient Photocatalytic Hydrogen and Oxygen Evolution by Side‐Group Engineered Benzodiimidazole Oligomers with Strong Built‐in Electric Fields and Short‐Range Crystallinity

AbstractThe insufficient charge separation and sluggish exciton transport severely limit the utilization of polymeric photocatalysts. To resolve the above issues, we incorporate bountiful carboxyl substituents within a novel benzodiimidazole oligomer and assemble it into a crystalline semiconductor. The photocatalyst is polar, hydrophilic, short‐range crystalline, and capable of both hydrogen and oxygen evolution. The introduction of carboxyl side‐groups adds asymmetry to the local structure and increases the built‐in electric field. Further, accelerated carrier transfer is enabled via the short‐range crystallinity. The superior hydrogen and oxygen production rates of 18.63 and 2.87 mmol g−1 h−1 represent one of the best performances ever reported among dual‐functional polymeric photocatalysts. Our work initiates studies on high‐performance oligomer photocatalysts, opening a new frontier to produce solar fuel.

Piezo-Photocatalytic Synergy in BiFeO3 @COF Z-Scheme Heterostructures for High-Efficiency Overall Water Splitting.

Solar-driven overall water splitting is an ideal way to generate renewable energy while still challenging. For the first time, this work combined covalent organic frameworks (COFs) and piezoelectric material by covalent linkages to form Z-scheme core@shell heterostructure for overall water splitting. Benefiting from the synergistic effect between the polarized electric field and photo-generated charges, as well as the precise adjustment of shell thickness, the carrier separation and utilization efficiency is greatly improved. The optimal BiFeO3 @TpPa-1-COF photocatalyst revealed hydrogen (H2 ) and oxygen (O2 ) production rates of 1416.4 and 708.2 μmol h-1 g-1 under the excitation of ultrasonication coupled with light irradiation, which is the best performance among various piezo- and COF-based photocatalysts. This provides a new sight for the practical application of highly efficient photocatalytic overall water splitting.

Piezo‐Photocatalytic Synergy in BiFeO3@COF Z‐Scheme Heterostructures for High‐Efficiency Overall Water Splitting

AbstractSolar‐driven overall water splitting is an ideal way to generate renewable energy while still challenging. For the first time, this work combined covalent organic frameworks (COFs) and piezoelectric material by covalent linkages to form Z‐scheme core@shell heterostructure for overall water splitting. Benefiting from the synergistic effect between the polarized electric field and photo‐generated charges, as well as the precise adjustment of shell thickness, the carrier separation and utilization efficiency is greatly improved. The optimal BiFeO3@TpPa‐1‐COF photocatalyst revealed hydrogen (H2) and oxygen (O2) production rates of 1416.4 and 708.2 μmol h−1 g−1 under the excitation of ultrasonication coupled with light irradiation, which is the best performance among various piezo‐ and COF‐based photocatalysts. This provides a new sight for the practical application of highly efficient photocatalytic overall water splitting.

In-situ construction of photoanode with Fe2O3/Fe3O4 heterojunction nanotube array to facilitate charge separation for efficient water splitting

Hematite (α-Fe 2 O 3 ), as a promising material in photoelectrochemical water splitting, has been given much attention to enhance its performance through a series of modifications. In this work, anodized Fe 2 O 3 nanotubes were annealed in air and then in argon atmosphere. The samples annealed in argon underwent partial escape of oxygen atoms, thus generating Fe 3 O 4 and eventually forming Fe 2 O 3 /Fe 3 O 4 heterojunction in situ. The built-in electric field constructed by the heterojunction establishes a channel for effective charge transfer. In addition, the formation of heterojunction not only accelerates the charge transfer at the interface, but also shortens the band gap and promotes light absorption. As a result, the two-step annealed sample showed the best photoelectrochemical performance with a photocurrent of 2.5 mA cm −2 photocurrent at 1.6 V νs . RHE, threefold that of pure Fe 2 O 3 nanotubes (0.75 mA cm −2 ). The highest hydrogen production rate and oxygen production rate reached 23.84 and 15.66 μmol cm −2 h −1 , respectively. The facile two-step annealing method to generate Fe 2 O 3 /Fe 3 O 4 heterojunction in-situ contributes to solving the problem of short cavity diffusion length and slow water oxidation kinetics. • Fe 2 O 3 /Fe 3 O 4 heterojunction was in situ constructed by two-step annealing. • Mechanism of phase transition from Fe 2 O 3 to Fe 3 O 4 is explained. • In-situ constructed heterojunctions improve separation and transport of carriers.

Municipal wastewater treatment and fouling in microalgal-activated sludge membrane bioreactor: Cultivation in raw and treated wastewater

Since the advent of conventional activated sludge biological treatment plants, their low efficiency in nitrogen and phosphorus removal has become a significant concern. Therefore, in this study, the performance of microalgal-activated sludge membrane bioreactor (MAS-MBR) as a self-biological treatment or as a post-treatment for conventional biological treatments was investigated. A continuous MAS-MBR with two ratios of algae/sludge (only microalgae and 5:1) was used to treat raw and treated wastewater. The optimum case was achieved with the cultivation of mixed algae/sludge in raw wastewater (R2 case). In this case, the ammonium and phosphorus removal efficiencies were 94.36 ± 3.5 and 88.37 ± 3 %, respectively. Furthermore, the highest oxygen production rate (OPR) and oxygen uptake rate (OUR) values were obtained in this case (145.58 ± 3 and 68.43 ± 1.5 mgO2/lit.d, respectively). In addition, membrane fouling was adversely increased in R2 compared with other cases, indicating the necessity of membrane cleaning for high-performance bioreactors in nutrient removal. Transmembrane pressure (TMP) jump in R2 was captured after 14 days, while the results supported that the membrane fouling was influenced by raised production of carbohydrate fraction of soluble microbial products (SMPc) and protein fraction of extracellular polymeric substances (EPSp) at first and last stages, respectively. Therefore, although the MAS-MBR is a potential candidate as a self-biological treatment, the membrane fouling is high in this case.

Visible light active IrO2/TiO2 films for oxygen evolution from photocatalytic water splitting in an optofluidic planar microreactor

An optofluidic planar microreactor has been fabricated, with the photocatalyst (IrO2/TiO2) film coated glass as a reactor plate and plain glass as a cover plate. A rectangular region was completely etched on plain glass and used as a spacer between reaction and cover plates to create a planar microreaction compartment. The water splitting activity to produce oxygen using sodium iodate as a sacrificial agent (electron acceptor) was tested in the fabricated planar microreactor under visible light illumination (with 400 W metal halide lamp). The effect of catalyst coating thickness and the reactant flowrate on the rate of oxygen production was studied in detail. An oxygen evolution rate of 3.99 mmol h−1 g−1 (1.84 μmol h−1 cm−2) was observed from the IrO2/TiO2 film of 3078 ± 362 nm thickness at an optimal flow rate of 0.3 mL min−1 in the presence of visible light. The stability study showed that the IrO2/TiO2 film was stable for at least 4 cycles, indicating the superior activity of the film firmly adhered to the glass substrate.