Recently, reversible addition–fragmentation chain transfer (RAFT)-mediated polymerization-induced self-assembly (PISA) has emerged as a powerful method for the preparation of a variety of block ...copolymer nano-objects. Although numerous RAFT-mediated PISA formulations have been successfully explored, inert atmospheres (e.g., nitrogen) are often needed to overcome the oxygen inhibition problem, making this process challenging when polymerizing at low volumes. Moreover, this restriction also reduces the versatility of RAFT-mediated PISA for non-experts. Herein, we report an efficient photoinitiated polymerization-induced self-assembly (photo-PISA) with excellent oxygen tolerance through dual-wavelength type I photoinitiation and photoinduced deoxygenation. The dual-wavelength photo-PISA was explored in water and alcohol/water using 2-hydroxypropyl methacrylate (HPMA), benzyl methacrylate (BzMA), and isobornyl acrylate (IBOA) as core-forming monomers. Polymerization kinetics indicated that dual-wavelength photo-PISA was performed in a batch reactor, flow reactor, and microliter plate with excellent oxygen tolerance. Block copolymer nano-objects with different morphologies (spheres, worms, and vesicles) were successfully prepared by these dual-wavelength photo-PISA techniques. This is a fast RAFT-mediated PISA under air, which is a clear improvement from previous systems. We believe that this method can greatly increase the accessibility of RAFT-mediated PISA for the preparation of block copolymer nano-objects either at low volumes or at a large scale.
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IJS, KILJ, NUK, PNG, UL, UM
The CO2 that comes from the use of fossil fuels accounts for about 65% of the global greenhouse gas emission, and it plays a critical role in global climate changes. Among the different strategies ...that have been considered to address the storage and reutilization of CO2, the transformation of CO2 into chemicals or fuels with a high added-value has been considered a winning approach. This transformation is able to reduce the carbon emission and induce a "fuel switching" that exploits renewable energy sources. The aim of this brief review is to gather and critically analyse the main efforts that have been made and achievements that have been made in the electrochemical reduction of CO2 for the production of CO. The main focus is on the prospective of exploiting the intrinsic nature of the electrolysis process, in which CO2 reduction and H2 evolution reactions can be combined, into a competitive approach, to produce syngas. Several well-established processes already exist for the generation of fuels and fine-chemicals from H2/CO mixtures of different ratios. Hence, the different kinds of electrocatalysts and electrochemical reactors that have been used for the CO and H2 evolution reactions have been analysed, as well as the main factors that influence the performance of the system from the thermodynamic, kinetic and mass transport points of view.
The synthesized GO/MgO nanoflower with high electrocatalytic performance can be used as cathode catalyst in single chamber microbial fuel cell to generate bioelectricity and degrade organic matters.
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•A facile and effective method to synthesize graphene oxide/magnesium oxide nanocomposite.•Magnesium oxide catalyst is successfully attached with surface of graphene oxide.•Microbial fuel cells with GO/MgO generate a high power density of 755.63mWm−2.•This composite electrode exhibits excellent electrocatalytic activity.
Microbial fuel cell (MFC) is a promising device which can simultaneously deal with pollutions and generate renewable electricity power. In a single-chamber MFC, the performance of cathode catalyst is one of the key factors that determine power generation. In this study, we applied the nanoflower-shaped graphene oxide hybridized MgO (GO/MgO) nanocomposite to the cathode carbon cloth, which could significantly optimize the reactors’ performance at a low price. A series of characterizations on GO/MgO confirmed that the magnesium oxide was successfully decorated on the surface of graphene oxide. The oxygen reduction reaction (ORR) test of cathode indicated that the electrochemical activity of GO/MgO cathode was higher than a bare MgO cathode or pure GO cathode. Consequently, the power density of MFC catalyzed by GO/MgO was enhanced to 755.63mWm−2, which was equivalent to 86.78% of MFCs catalyzed by Pt/C (870.75mWm−2). In addition, it obtained a chemical oxygen demand removal efficiency of 79.5%, and a coulombic efficiency of 31.6%, which also saw the best result among the three cathodes. After approximately 20 cycles running, the power density of the MFC used GO/MgO cathode kept still a stable level. Especially, it saved 93.3% cost while comparing to Pt/C catalyst, but achieved a similar electrochemical result, which helps to realize a scale-up design.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The negative energy balance of wastewater treatment could be reversed if anaerobic technologies were implemented for organic carbon oxidation and phototrophic technologies were utilized for nutrient ...recovery. To characterize the potential for energy positive wastewater treatment by anaerobic and phototrophic biotechnologies we performed a comprehensive literature review and analysis, focusing on energy production (as kJ per capita per day and as kJ m(-3) of wastewater treated), energy consumption, and treatment efficacy. Anaerobic technologies included in this review were the anaerobic baffled reactor (ABR), anaerobic membrane bioreactor (AnMBR), anaerobic fluidized bed reactor (AFB), upflow anaerobic sludge blanket (UASB), anaerobic sequencing batch reactor (ASBR), microbial electrolysis cell (MEC), and microbial fuel cell (MFC). Phototrophic technologies included were the high rate algal pond (HRAP), photobioreactor (PBR), stirred tank reactor, waste stabilization pond (WSP), and algal turf scrubber (ATS). Average energy recovery efficiencies for anaerobic technologies ranged from 1.6% (MFC) to 47.5% (ABR). When including typical percent chemical oxygen demand (COD) removals by each technology, this range would equate to roughly 40-1200 kJ per capita per day or 110-3300 kJ m(-3) of treated wastewater. The average bioenergy feedstock production by phototrophic technologies ranged from 1200-4700 kJ per capita per day or 3400-13 000 kJ m(-3) (exceeding anaerobic technologies and, at times, the energetic content of the influent organic carbon), with usable energy production dependent upon downstream conversion to fuels. Energy consumption analysis showed that energy positive anaerobic wastewater treatment by emerging technologies would require significant reductions of parasitic losses from mechanical mixing and gas sparging. Technology targets and critical barriers for energy-producing technologies are identified, and the role of integrated anaerobic and phototrophic bioprocesses in energy positive wastewater management is discussed.
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•Effects of N/P deficiency on SVI, EPS, PHA and microbial community structure were examined.•Bulking was not encountered in reactors with nitrogen limitation or deficiency.•Bulking ...was encountered in those reactors fed with wastewater deficient in phosphorus.•N limitation/deficiency stimulates formation of intracellular storage products (PHA).•P limitation stimulates formation of carbohydrates.
Although the limitation or deficiency of nutrients, such as nitrogen (N) and phosphorus (P), has been one of the frequently reported factors causing filamentous or non-filamentous bulking of activated sludge, the mechanisms are still unclear. In this work, the long-term effects of N and P limitation or deficiency on sludge settleability and bioflocculation characteristics were investigated in six sequencing batch reactors (SBRs) fed with wastewater with different nutrient availability. The sludge volume index (SVI), microbial community structures, intracellular poly-β-hydroxyalkanoates (PHAs) and extracellular polymeric substances (EPS) were characterised over time. Bulking was not observed in SBRs with N limitation or deficiency, in which SVI remained below 150mL/g. In contrast, bulking was encountered in those reactors with P deficiency. The occurrence of non-filamentous bulking was associated with a higher carbohydrates fraction and a lower proteins fraction in EPS. In the case of filamentous bulking, SVI correlated negatively with the amount of PHAs. Our experimental data support the hypothesis that the occurrence and/or the type of bulking in activated sludge could be affected by the combination of kinetic selection, microbial storage, as well as the EPS composition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•The effect of magnetic powder addition on the performance of MAS-SBR was studied.•Adding magnetic powder could enhance the removal of pollutants and sludge reduction.•Magnetic powder addition ...significantly enriched the microbial diversity.
This study aims to investigate the effect of adding magnetic powder in the sequencing batch reactor (SBR) on the reactor performance and microbial community. Results indicated that, the magnetic activated sludge sequencing batch reactor (MAS-SBR) had 7.76% and 4.76% higher ammonia nitrogen (NH4+-N) and chemical oxygen demand (COD) removal efficiencies than that of the conventional SBR (C-SBR). The MAS-SBR also achieved 6.86% sludge reduction compared with the C-SBR. High-throughput sequencing demonstrated that the dominant phyla of both SBRs (present as ≥1% of the sequence reads) were Protebacteria, Bacteroidetes, Chloroflexi, Saccharibacteria, Chlorobi, Firmicutes, Actinobactoria, Acidobacteria, Planctomycetes and unclassified_Bacteria. The relative abundance of Protebacteria and Bacteroidetes simultaneously declined whereas the other 8 phyla increased following the addition of magnetic powder. Adding magnetic powder in the SBR significantly affected the microbial diversity and richness of activated sludge, consequently affecting the reactor performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Hydrogen production through supercritical water gasification (SWG) of biomass has been widely studied. This study reviews the main factors from exergy aspect, and these include feedstock ...characteristics, biomass concentration, gasification temperature, residence time, reaction catalyst, and reactor pressure. The results show that the exergy efficiencies of hydrogen production are mainly in the range of 0.04–42.05%. Biomass feedstock may affect hydrogen production by changing the H2 yield and the heating value of biomass. Increases in biomass concentrations decrease the exergy efficiencies, increases in gasification temperatures generally increase the exergy efficiencies, and increases in residence times may initially increase and finally decrease the exergy efficiencies. Reaction catalysts also have positive effects on the exergy efficiencies, and the reviewed results show that the effects are followed KOH > K2CO3 > NaOH > Na2CO3. Reactor pressure may have positive, negative or negligible effects on the exergy efficiencies.
•Hydrogen production from supercritical water gasification of biomass is reviewed.•Exergy efficiencies as affected by the main parameters are presented.•Feedstock characteristics, biomass concentration, and gasification temperature are covered.•Residence time, reaction catalyst, and reactor pressure are also covered.•Exergy efficiencies of hydrogen production are mainly in the range of 0.04–42.05%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bifunctional hydrodeoxygenation catalysts containing both metal and metal oxide phases are widely employed in biomass upgrading reactions. Determining the oxidation state of metals in such complex ...reaction media has been challenging. In this work, we developed a high-pressure trickle-bed reactor capable of conducting temperature-programed reduction of catalysts after liquid-phase reactions without exposing the catalyst bed to ambient conditions. Two case studies on metal/metal oxide catalysts employed in key biomass upgrading processes were investigated. The reduction of the RuO x phase in Ru/RuO x /SiO2 occurs at temperatures as low as 115 °C via catalytic transfer hydrogenation reactions using liquid 2-propanol as a hydrogen source. Pretreatment of Ir-ReO x /SiO2 catalyst with H2 in the presence of either liquid cyclohexane or liquid water reduces Re to an oxidation state of +2.6, while the residual ReO x phase cannot be reduced in H2 at up to 900 °C.
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IJS, KILJ, NUK, PNG, UL, UM
Mathematical modeling of batch production of high vinyl random styrene/butadiene copolymers in an industrial batch reactor was accomplished. Mass and energy balance equations were solved to model the ...nonisothermal anionic copolymerization of styrene/butadiene performed in an industrial batch reactor. The simulation model allows to predict the variation of the individual and global monomer conversion(s), temperature, pressure, and volume level of reactor with the time. Simulation model was used to determine the optimal polymerization conditions to maximize the production of a high vinyl random styrene/butadiene copolymer used in the manufacture of high performance tires.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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