Experimental investigation on dyeing wastewater treatment and by-product hydrogen with a reverse electrodialysis flocculator

Hydrogen production and dye degradation can be achieved simultaneously in a hybrid system of reverse electrodialysis（RED）and electrocoagulation (EC), using current derived from the salinity gradient energy. Under the current, Fe electrode is used as the anode to produce Fe²⁺(subsequently oxidized to Fe³⁺) which combines with OH⁻ produced from the cathode to remove the dyes, while the hydrogen gas produced by the cathode is collected by a hydrogen collection device. The experiments are carried out to investigate the effects of different initial concentrations, pH, currents, electrode rinse solution (ERS) flow rates and the addition of chlorine on the degradation rate and hydrogen production. The results indicate that the degradation rate and hydrogen production could reach 98.3% and 150 m h⁻¹ at alkaline condition (pH = 11) and acidic condition (pH = 3) respectively, with a current of 0.4 A. The degradation rate and hydrogen production increase significantly with an increase in current.     

Enhanced transmittance of Y2O3 transparent ceramics from near-UV to near-infrared through reduced atmosphere annealing

Y₂O₃ transparent ceramics were annealed under different atmospheric conditions. The samples annealed in H₂ containing atmosphere were colorless and had high in-line transmittances from the near-UV to the mid-infrared wavelength range. This is due to the elimination of carbon contamination and preventing the formation of high concentration oxygen interstitial defects in the sintered samples. Annealing in oxygen containing atmosphere resulted in stronger optical absorption in the visible wavelength region. High temperature annealing in O₂ or hot isostatic pressing under high partial pressure of O₂ (O₂ HIP) led to obviously declining of transparency in a broader wavelength range of 230–800 nm. The Er:Y₂O₃ ceramics annealed in H₂ containing atmosphere had high in-line transmittance of about 80% at 400 nm as well. Room temperature laser oscillation at 2.7 µm was also obtained on the 5%H₂/95%Ar atmosphere annealed Er:Y₂O₃ ceramics.     

Design of the PID temperature controller for an alkaline electrolysis system with time delays

Electrolysis systems use proportional–integral–derivative (PID) temperature controllers to maintain stack temperatures around set points. However, because of heat transfer delays in electrolysis systems, the manual tuning of PID temperature controllers is time-consuming, and temperature oscillations often occur. This paper focuses on the design of the PID temperature controller for an alkaline electrolysis system to achieve fast and stable temperature control. A thermal dynamic model of an electrolysis system is established in the frequency domain for controller designs. Based on this model, the temperature stability is analysed by the root distribution, and the PID parameters are optimized considering the temperature overshoot and the settling time. The performance of the optimal PID controllers is experimentally verified. Furthermore, the simulation results show that the before-stack temperature should be used as the feedback variable for small lab-scale systems to suppress stack temperature fluctuations, and the after-stack temperature should be used for larger systems to improve the economy. This study helps ensure the temperature stability and control of electrolysis systems.     

Prospecting the biofuel potential of new microalgae isolates

The continued search and urgent need for renewable fuel sources have necessitated the exploration of microalgae to identify relevant species for making biofuels. The aim of the study was bioprospecting and screening native microalgae strains from freshwater habitats of the Almaty region, Kazakhstan, to assess the potential for producing biofuel. The studied strains demonstrated simultaneous biomass productivity, lipid productivity, suitable fatty acid composition, and biodiesel properties. The sequence analysis of the ribosomal DNA internal transcribed spacer partial region and ribulose-bisphosphate carboxylase gene (rbcL) led to the identification of five microalgae: Monoraphidium griffithii ZBD-01, Nephrochlamys subsolitaria ZBD-02, Ankistrodesmus falcatus ZBD-03, Parachlorella kessleri ZBD-04, and Desmodesmus pannonicus ZBD-05. P. kessleri had the highest biomass production (1.42 ± 0.08 g L⁻¹ day⁻¹), lipid productivity (29 ± 1.2 g L⁻¹day⁻¹), and C₁₆–C₁₈ fatty acid contents (90%), followed by A. falcatus and M. griffithi. Gas chromatography/mass spectrometry analysis indicated that the dominant fatty acids in these strains were palmitic, stearic, and oleic acids. The calculated biodiesel properties of P. kessleri and A. falcatus based on fatty acid methyl esters (FAME) profiles showed relatively good fuel properties (cetane numbers - 48 and 50; iodine and saponification values - 83.4 and 103.6 g I₂/100 g oil, 260.8 and 199.5 mg KOH g⁻¹), which correlate well with. Our results suggest that P. kessleri and A. falcatus are promising strains for biodiesel production due to their high lipid productivity, fatty acid profile with relatively high content of oleic acid, and suitable biodiesel properties. The isolated native species of microalgae from natural freshwater bodies of the Almaty region present opportunities for further exploitation for the sustainable production of biomass and biodiesel.     

Hierarchically porous carbon from biomass tar as sustainable electrode material for high-performance supercapacitors

The byproduct tar from biomass gasification process had seriously impeded development and applications of this technology, thus novel path for biomass tar valorization is had been continuously pursued. Given its high carbon content, this work attempted to convert biomass tar into hierarchically porous carbon by thermal activation with acetate potassium. The optimal product produced with mass ratio of biomass tar to acetate potassium of 1:3 and activation temperature at 800 °C was revealed as excellent electrode material for high-performance supercapacitor, which demonstrated electrochemical capacitance up to 310.4 F/g at 0.2 A/g, whilst preserved 91% of initial capacitance after 5000 charge-discharge circles at current density of 5 A/g. These excellent properties had arisen from the open and hierarchical porosity and large surface area. This work disclosed the great potential of biomass tar as sustainable and competent candidate for fabricating high-performance electrode material for electrochemical energy devices, and may bring up new opportunities to development of biomass gasification technologies.     

Mixed-valence molybdenum ion incorporated graphitic carbon nitride with high photocatalytic H2 evolution activity

The graphitic carbon nitride (CN) incorporated with mixed-valence molybdenum ion has been prepared via in-situ copolymerization to improve the photocatalytic H₂ evolution performance. The introduced Mo species existed in mixed valence of Mo⁴⁺ and Mo²⁺ state and its content could be tuned by simply adjusting amount of added MoCl₅ in the preparation procedure. The incorporated mixed-valence Mo ions contributed to narrowed band gap, increased electron density and elevated electron motion kinetics, resulting in extended visible light response, promoted separation and transportation of photoexcited charge carriers. The obtained CN–Mo photocatalyst with an optimal content of Mo ions (0.41 wt%) exhibited a robust H₂ production activity up to 1.44 mmol h⁻¹ g⁻¹, 18 times higher than that of pristine counterpart.     

Construct organic/inorganic heterojunction photocatalyst of benzene-ring-grafted g-C3N4/CdSe for photocatalytic H2 evolution

Photocatalytic water splitting to produce hydrogen is a vital research direction for alleviating the energy crisis. Herein, benzene-ring grafted g-C₃N₄ nanotubes (Ph-g-C₃N₄) were prepared skillfully and coupled with CdSe nanoparticles which was realized efficiently hydrogen production. The addition of CdSe nanoparticles enhanced the stability of the catalytic system dispersion in water, and the absorbance of the composites catalyst CdSe/Ph-g-C₃N₄ (CPG) was enhanced. In addition, the CPG had been characterized to have low resistance and efficient photogenerated electron separation efficiency. The Ph-g-C₃N₄ nanotubes with a three-dimensional structure can provide an anchoring platform for CdSe nanoparticles and effectively prevent the agglomeration of CdSe. The constructed composites catalyst achieved the efficient transfer of photogenerated electrons as known from photoluminescence spectroscopy test analysis. When CdSe nanoparticles were anchored to Ph-g-C₃N₄, the electron transfer rate of the constructed composite was about twice that of the Ph-g-C₃N₄, which facilitates the hydrogen evolution reaction. The character and electron transfer pathways of the photocatalysts were investigated theoretically by performing density functional calculations. The finding provides a new idea for the doping of photocatalysts and the design of organic/inorganic heterojunction composites photocatalyst to achieve an efficient hydrogen production system.     

基于模糊逻辑与遗传算法的燃料电池热管理方法研究

有效的质子交换膜燃料电池(Proton Exchange Membrane Fuel Cell,PEMFC)热管理是提升氢燃料电池汽车安全性、耐久性以及运行效率的关键因素之一.该文提出一种PEMFC电堆热管理控制方法,使电堆出入口温度保持在设定值.该方法以PEMFC热管理系统模型中电堆出入口温度的变化为依据,设计一种二...