In this work, a bioprocess for the fermentation of A. succinogenes for the production of succinic acid from glycerol was developed, employing a continuous bioreactor with recycle. Moreover, a new ...bioprocess model was constructed, based on an existing double substrate limitation model, which was validated with experimental results for a range of operating parameters. The model was used to successfully predict the dynamics of the continuous fermentation process and was subsequently employed in optimisation studies to compute the optimal conditions, dilution rate, reflux rate and feed glycerol concentration, that maximise the productivity of bio-succinic acid. In addition, a Pareto front for optimal volumetric productivity and glycerol conversion combinations was computed. Maximum volumetric productivity of 0.518 g/L/h, was achieved at the optimal computed conditions, which were experimentally validated. This is the highest bio-succinic acid productivity reported so far, for such a continuous bioprocess.
The increasing environmental burden generated by disposable plastic wastes makes the development of sustainable substitute materials an emergent task. As one of the most abundant bioresources, ...chitosan (CS) has been considered as a potential candidate for plastic substitution. Conventionally, CS-based materials are fabricated through a solution-processing procedure due to the high crystallinity of CS. Herein, we designed a CS-based material via integrating CS into the network of polyimine (PI), which shows thermomechanical processability similar to plastics. Strong interactions were achieved through dynamic imine bond and hydrogen bond and thus formed a thermo-processable dynamic composite network. These CS-based plastic substitutes exhibit exceptional mechanical performances, excellent thermal/chemical stability, and a series of self-adaptiveness, including re-healing, reprocessing and multi-layer laminating. Notably, CPs can be easily degraded and 100% recycled for the production of next-generation materials. This work provides an alternative route to produce green and sustainable biomass materials as a plastic substitute.
Display omitted
Biomass supercritical water gasification is clean and renewable, which can convert biomass into hydrogen rich gas. Previous studies indicated that external recycle of liquid residual could improve ...gas yield and gasification efficiency. However, the influence mechanism of external recycle on energy and exergy efficiency is complicated and theoretical model for system optimization is insufficient. Thermodynamic model of external recycle of liquid residual was built in this paper. Exergy efficiency of the main components and exergy loss distribution were specified and the result showed that exergy loss of reactor and preheater accounted for 26.06% and 35.88% of the total exergy loss, which were the main exergy loss sources. Effective ways to reduce exergy loss of components with large exergy loss and to improve energy and exergy efficiency of the system were proposed. Moreover, life cycle assessment of biomass gasification process was carried out. The results indicated that the increase of gasification temperature, pressure and external recycle flow rate of liquid residual and decrease of biomass concentration could improve energy and exergy efficiency of the system. Energy and exergy efficiency reached 63.67% and 48.29% respectively at the condition of gasification temperature of 560 °C, pressure of 25 MPa, recycle flow ratio of 32.43%, biomass concentration of 2.78%. Besides, the increase of gasification temperature and decrease of biomass slurry concentration and pressure could decrease GWP.
Thermodynamics and LCA analysis of biomass supercritical water gasification using external recycle system was conducted. Display omitted
•Material, mass and energy balance of the system and each component was achieved.•Component with largest exergy loss was found and solutions were proposed.•Approaches to improve energy and exergy efficiency of the system were proposed.•LCA of biomass gasification in SCW was conducted.•Highest energy and exergy efficiency reached 63.67% and 48.29% respectively.
In this paper, the optimization of the methanol production process is investigated. For this purpose, the parameters affecting methanol production including catalyst type (4 cases), temperature, ...pressure, and GHSV have been investigated and then by selecting the appropriate catalyst and process conditions, possible process changes such as hydrogen injection as make up, applying two reactors and inert gases, the use of dry hydrogen, and adding recycle stream on methanol yield have been studied.
Then, by selecting the appropriate process, simulating, and validating the simulation results, the selected catalyst is used for the process. The process is simulated in 8 cases with changes in the studied parameters and the amount of recycle flow. Then, the key parameters of the optimized process were compared with the baseline. The results showed that, the investment costs (smaller dimensions of process equipment such as compressors, reactors, and distillation columns, etc. due to recycling flow reduction) and current costs (including electricity and steam consumption), significantly improved.
In general, the use of CuZnOAl2O3 catalyst in the methanol production process reduced the reactor temperature, decreased the recycle flow by about 38% and reduced the electrical energy consumption and steam consumption relative to the baseline by about 5% and 67%, respectively. Finally by the process optimization conducted in this work, in addition to reducing the recycle flow and reducing energy consumption, it is possible to annually reduce the GHG emissions of 7526.35 ton CO2eq and 19.43 tons of air pollutants (per 100 kton/y of methanol production).
•The process parameters affecting methanol production were optimized.•The recycle flow and energy consumption were reduced by 38% and 17%, respectively.•The GHG and air pollutants were decreased by about 16.9% relative to the baseline.
Shape, size, and orientation of fillers within polymer matrix are important factors for realizing various composite functionalities. Here, we describe an industrially scalable approach to preparing ...composites bearing highly aligned model hexagonal boron nitride filler (hBN) by simple melt-pressing. This outcome is achieved by using a malleable but thermal stiffening polymer matrix. The matrix maintains or even increases its stiffness during processing at elevated temperatures, producing the composites with highly aligned hBN and consequently a high thermal conductivity (28 W/mK). Furthermore, the composite bearing aligned hBN exhibits a 62% reduction in oxygen permeation with only 2.7 vol% of hBN. Since the matrix can be chemically depolymerized with an aid of acid, it is also possible to recover the hBN from the composite without physical/chemical denaturation of the filler, thus the recovered filler can be re-used in the future.
Display omitted
•A malleable but thermal stiffening polymer was used as matrix to produce the composites with highly shear aligned hBN.•The composite exhibited exceptionally high isotropic thermal conductivity of 28 W/mK.•The composite bearing highly aligned hBN exhibits a 62% reduction in oxygen permeation with only 2.7 vol% of the hBN.•The filler could be recovered from the composite by depolymerizing the matrix, thus the filler is readily reusable.
•The Hg0 removal by CuCl2-MF technology was applied to large coal-fired units.•The mercury removal performance of CuCl2-MF with different conditions were studied.•The optimal magnetosphere injection ...parameters were assured by the results of tests.•CuCl2-MF showed superior Hg0 removal ability and mercury recovery performance.
CuCl2–MF was a cost–efficient and highly efficient sorbent for Hg removal from flue gas in coal-fired units. In this study, the Hg0 adsorption and oxidation performance of CuCl2–MF with different conditions were studied at a 1000 MW commercial scaled coal-fired power plant. Under the optimal conditions, the total removal efficiency of Hg and the Hg recovery rate reached 98.72% and 52.76% using CuCl2–MF injection combined with the existing pollutant control device. The magnetosphere particle size of 45 μm–75 μm exhibited the highest mercury removal capacity. Additionally, the final mercury emission concentration was 0.334 μg/m3 and the corresponding relative mercury removal efficiency was 89.81%. The results of this study proved that elemental mercury removal by CuCl2–MF was also suitable for large-scale coal-fired units with a high Hg removal efficiency even in the low concentrations of mercury, which provided a reference for the practical application of this technology in other units in the future and supplied valuable experience for other mercury removal technologies.
There is a clear economic benefit for the recycling of metallic powder during additive manufacturing (AM). Laser powder bed fusion (L‐PBF) is one such AM process and research has found that the ...properties of the powder feedstock can change when the powder is reused through mechanisms such as spatter generation and alterations in chemistry. Such changes to powder properties can accumulate and may lead to significant differences in the mechanical properties of the final component. Often the changes to part properties are reasonably small; however, there is not currently enough understanding of the specific links between powder properties and the characteristics of the end component for the effects of powder recycling to be discounted. Herein, the typical lifecycle of stainless steel 316L powder in L‐PBF, the changes that occur to the powder feedstock, and the effects that this may have on the mechanical properties of components manufactured with recycled powder are reviewed.
This paper reviews the typical lifecycle of stainless steel 316L powder in the additive manufacturing process laser powder bed fusion, the changes that occur to the powder feedstock, and the effects that this may have on the mechanical properties of components manufactured with recycled powder.
Display omitted
•Ultrafine RuNPs stabilised by a phosphine oxide-modified polymer immobilized ionic liquid.•Complete selectivity for the partial reduction of aromatic and heteroaromatic nitroarenes ...to the corresponding N-arylhydroxylamine.•Highest initial turn over frequency to be reported for a RuNP catalysed partial reduction of nitrobenzene to N-phenylhydroxylamine.•Reduction of electron rich amino nitroarenes to the aniline proposed to occur via a quinondiimine-derived iminium.•High activity and selectivity retained over five reuses with only a minor reduction in conversion.
RuNPs stabilised by a polymer immobilised ionic liquid derived from co-polymerisation of a PEG-substituted imidazolium-based styrene monomer and diphenyl(4-vinylphenyl)phosphine oxide, RuNP@O = PPh2-PEGPIILS, (2) is a remarkably efficient and selective catalyst for the hydrazine hydrate-mediated partial reduction of nitroarenes to the corresponding N-arylhydoxylamine. Near quantitative conversion to N-phenylhydroxylamine with > 99 % selectivity was obtained after only 2 h when the reaction was conducted at 25 °C in ethanol under an inert atmosphere using 0.1 mol% catalyst. Under these conditions, the composition-time profile showed that the reduction occurred via the direct pathway whereas reactions in air gave a mixture of azoxy-based products due to competing condensation resulting from reversible formation of N-phenylhydroxylamine. The initial TOF of 6,100 h−1 obtained after 10 min at 40 °C with 0.1 mol% 2 is among the highest to be reported for the metal nanoparticle catalysed reduction of nitrobenzene to N-phenylhydroxylamine and a significant improvement on 5 wt% Ru/C which gave a modest conversion of 21 % (initial TOF = 240 h−1) to a mixture of N-phenylhydroxylamine and aniline. A broad range of substituted N-aryl and N-heteroaryl nitroarenes were reduced to the corresponding N-arylhydroxylamine in high yield and with excellent selectivity by adjusting the reaction times. However, reduction of electron rich amino-substituted nitroarenes was extremely slow and resulted in reduction to the aniline with no evidence for the corresponding hydroxylamine. Complete reduction of amino substituted nitroarene is proposed to be facilitated by amine-assisted elimination of hydroxide from the hydroxylamine to afford a readily reducible quinondiimine-derived iminium intermediate that reacts with a surface hydride to liberate the amine. Under optimum conditions the catalyst could be reused five times for the reduction of nitrobenzene to N-phenylhydroxylamine with no detectable change in activity and only slight decrease in selectivity.
Here we report a facile reusable method for graphene oxide (GO) from the oxidation of waste graphite anode scrap (WGAS), which was synthesized by Couette–Taylor flow reactor. The toroidal motion of ...fluids generated by the mechanical and structural specificity of the reactor increased the intercalation rate and oxidation efficiency of the WGAS, resulting in high production yield (95 ± 1%) of GO within 90 min reaction time. In addition, the as-synthesized GO nanosheets were extensively characterized using a variety of techniques, which allowed the identification of two-dimensional monolayers (∼1.3 nm) and successfully functionalized high-quality graphene oxides. Our approach of the high-efficiency oxidation and exfoliation of recycled GO with WGAS may find potential application in numerous industrial fields, such as catalysis and electrodes in energy conversion and storage systems, and conductive materials in electronic devices.
