Search

The CO2absorption capacities of potassium glycinate, potassium sarcosinate (choline, proline), mono-ethanolamine (MEA), and tri-ethanolamine were evaluated to find the optimal absorbent for separating CO2from gaseous products by a CO2purification process. The absorption loading, desorption efficiency, cost, and environmental tolerance were assessed to select the optimal absorbent. MEA was found to be the optimum absorbent for separating the CO2and H2mixture in gaseous product. The maximum absorption loading rate was 0.77 mol CO2per mol MEA at temperature of 20°C and absorbent concentration of 2.5 mol/L, whereas desorption efficiency was 90% by heating for 3 h at 130°C. MEA was found to be an optimal absorbent for the purification process of CO2during gaseous production. [ABSTRACT FROM AUTHOR]

Abstract: Fermentative H2 production was operated at different hydraulic retention time using a continuously stirred tank reactor (CSTR) containing suspended H2-producing sludge. The H2 production rate (HPR) increased with a decrease of HRT from 12 to 6h, giving an optimal HPR of 0.6l/h/l at for CSTR operation. However, when the HRT was further shortened to 4h, both HPR and H2 yield decreased significantly. The poor H2-producing performance at 4h HRT is mainly attributed to the marked decrease in biomass content in the reactor due to severe cell washout, as the biomass concentration decreased to a low level of 1.63gVSS/l (volatile suspended solid, VSS). Bioreactor design strategies were applied to improve cell retention under a high substrate feeding rate. Silicone-immobilized cells (immobilized-cell-seeded anaerobic bioreactor (ICSAB system)) or powered activated carbon carriers (AGSB system) were added into the reactor to either maintain stable biomass concentration in the reactor or enhance biomass content by stimulating sludge granulation. Both ICSAB and agitated granular sludge bed (AGSB) showed improvement in biomass retention while operating at a HRT of 4h. In particular, the biomass concentration in AGSB system went up to 10.3VSS/l, leading to a drastic enhancement in H2 producing-performance (0.97l/h/l and 1.54molH2/mol glucose) Bacterial community analysis by denatured gradient gel electrophoresis (DGGE) indicates a transition in bacterial composition in CSTR under different HRT operation. Moreover, under the same HRT (4h) the major bacterial populations in AGSB and ICSAB reactors were very different from those observed in CSTR, indicating that the performance of H2 production seemed to be in close connection with the bacterial community structure. Several Clostridium species known as H2 producers were also detected in the sludge samples by DGGE and 16S rDNA sequence matching, revealing the effectiveness of the H2-producing sludge used in this study. [Copyright &y& Elsevier]

In this work, a dark H2 fermentation process was integrated with a proton-exchange-membrane fuel-cell (PEMFC) system for on-line electricity generation. The H2 producing system was a continuously stirred anaerobic bioreactor (CSABR) seeded with silicone-immobilized sludge. The CSABR system, using sucrose as the sole carbon substrate, was able to continuously and stably produce H2 for over 300 days at a hydraulic retention time (HRT) of 6h and an influent sucrose concentration of 30g COD/l. The maximum H2 production rate and the optimal H2 yield were and sucrose, respectively. The H2 produced from the CSABR system was purified via a CO2 absorber and a silica-gel desiccator, and then the pure H2 was fed into a PEMFC system at a rate of 1.72l/h, generating electricity with a stable electromotive force of . The output power was ca. 0.87W (at ), and the output voltage and current were stably maintained at 2.28V and 0.38A, respectively, when connected to a small light emission diode (LED) panel. [Copyright &y& Elsevier]

Abstract: A draft tube fluidized bed reactor (DTFBR) containing immobilized cell particles was designed to produce H2 continuously. A synthetic polymer (silicone gel; SC) was used as the primary material to immobilize acclimated anaerobic sludge for H2 production in DTFBR with a working volume of 8L. The DTFBR system was operated at a hydraulic retention time (HRT) of 2.2–8.9h and an influent sucrose concentration ( of 5–40g COD/l. The results show that in general decreasing HRT or increasing sucrose concentration led to a marked increase in the volumetric H2 production rate (, but a gradual decrease in the H2 yield (. The best () occurred at COD/l and , whereas the highest ( H2/mol sucrose) was obtained at COD/l and . The correlation between the production rate and the organic loading rate (OLR) can be satisfactorily described by Monod-type models. There was no universal trend of the dependence between the H2 yield and OLR. The H2 content in the biogas was stably maintained at over 40%. The major soluble products were butyric acid and acetic acid, as they accounted for 62–73% and 16–22% of total soluble microbial products (SMPs), respectively. The H2-producing performance in the DTFBR system can be stably maintained and reproducible in long-term operations, while unstable operations can be quickly recovered via proper thermal treatment at 70–80°C. [Copyright &y& Elsevier]

Abstract: A novel synthetic polymer (ethylene-vinyl acetate copolymer; EVA) was used to immobilize acclimated sewage sludge for H2 production under anaerobic conditions. Using sucrose as the sole carbon substrate, the resulting EVA-immobilized cells achieved an optimal H2 production rate () of 488mlH2/gVSS and the best substrate-based yield () of 1.74molH2/mol sucrose. Operation at a temperature of 40°C resulted in the most efficient H2 production. Acclimation of the sewage sludge allowed up to 3-fold enhancement on the performance of H2 production. Kinetic studies show that a Monod-type model is able to describe the dependence of specific H2 production rate on sucrose concentration. The immobilized cells maintained stable and efficient H2 production during 15 repeated runs, indicating excellent durability and stability of the immobilized-cell system. The composition of soluble metabolites was found to be a reliable indicator for the efficiency of biohydrogenation. [Copyright &y& Elsevier]

In this study, a self-adjusting concentration of graphene thermal grease was developed to reduce the contact surface thermal resistance of 50 W light-emitting diodes (LEDs). The purpose was to identify an important type of heat conduction material with a high thermal conductivity coefficient, which can be applied to the contact surface of various high-heat sources or concentrated heat sources to achieve seamless heat transfer with an extremely low thermal resistance state. The contact heat conduction material conductivity reached the highest K value of 13.4 W/m·K with a 15 wt.% self-adjusting concentration of graphene grease. This material could continuously achieve a completely uniform and rapid thermal diffusion of heat energy. Therefore, we performed an analysis of chip-on-board light-emitting diodes (LEDs) with a highly concentrated heat source, which showed excellent heat dissipation under natural convection heat transfer. As such, this study achieved the natural convection mechanism and a heat sink volume thermal performance capacity of 473,750 mm3 for LEDs under 50 W, but those over 50 W require an enhanced forced convection solution and a heat sink volume thermal performance capacity between 473,750 mm3 and 947,500 mm3. If the heat source dissipation reaches 100 W, the volume capacity must be at least 947,500 mm3 for lighting equipment applications. In the experimental study, we also verified and analyzed the research data, including an analysis of the measured data, grease component wt.%, heat sink material selection, increase in heat sink volume, heat transfer path, and contact surface, a discrimination analysis of infrared thermal images, and an analysis of flow visualization, which were conducted to ensure quantitative and qualitative improvement, provide a mechanism for judging the technical performance, and provide research results to enable discussion. [ABSTRACT FROM AUTHOR]

With the use of biotechnology, hydrogen can be produced from wastewater rich in short-chain fatty acids. A previous study revealed the ability of Rhodobacter sphaeroides KKU-PS1 to produce biohydrogen from substrates mimicking succinate fermentation effluent. However, the process still requires optimization. Before illumination optimization, due to high concentration of the effluent, various effluent dilution factors ranging from 10 to 100 were compared, and the optimal dilution factor was determined to be 50. Light-emitting diode (LED) setups consisting of bands and tubes were compared, and various illuminated surface-to-volume ratios (S/V) were obtained. LED tubes were subsequently used for light intensity optimization in the range of 5–23 klux, revealing optimum light intensity at 15 klux, yielding 2202 mL H 2 /L and 13.8 mL H 2 /L/h as the cumulative hydrogen and maximum output rate, respectively. The lighting protocol at 15 klux and with a 6h–6h light-dark cycle improved the total light conversion efficiency by up to 3.1%. The study successfully optimized the process, with results rivalling those of a previous study using malate. [Display omitted] • Photofermentation can convert acidic fermentation effluents to hydrogen energy. • Dilution factor of 50 produced H 2 profile that was comparable to higher dilutions. • Cumulative H 2 peaked at 2202 mL H 2 /L at maximum rate of 13.8 mL H 2 /L/h with 15 klux. • Light saturation point was observed at 15–23 klux with similar H 2 productivity. • 6h–6h light-dark cycle achieved the highest light conversion efficiency of 3.1% at 240 h. [ABSTRACT FROM AUTHOR]

In this study, polyethylene was pyrolysed in the fluidized-bed pyrolysis system in a limited oxygen supply. Thus, the heat to pyrolyse the polyethylene was made available by partial incineration of the polyethylene, which can be referred to as autothermal pyrolysis. The fluidized bed was selected as the reactor owing to its high capacity, homogeneity and low tar content. Experimental parameters evaluated included the effect of: (1) the pyrolysis temperatures; (2) the air factors; and (3 ) the catalyst on the liquid hydrocarbon (gasoline, diesel, fuel oil, residual) formation, and B. T X. (benzene, toluene, xylene) concentration in gasoline. Moreover, the primary composition in gasoline was analyzed. The results indicated that it is practical to recover oil from plastic waste using the autothermal pyrolysis system. [ABSTRACT FROM AUTHOR]

Acid treated rice straw hydrolysate was used as a substrate hydrogen production. Concentrated sulphuric acid (55%) was used to completely dissolve the rice straw cellulose at temperature of 40 °C. After hydrolysis of rice straw cellulose, calcium hydroxide was used to remove sulphate ions. Biohydrogen production was evaluated under different initial pH and substrate concentration conditions at a temperature of 37 °C in a batch mode. The maximum values of hydrogen yield and accumulation of hydrogen were 0.44 mol H2/mol T-sugar and 97.30 ± 0.17 mL with substrate utilization of 81.55% in a batch mode. A mixture of food industry wastewater with rice straw hydrolysate was used as substrate in a continuous mode for the biohydrogen production potential test in this study. The average hydrogen production yield of 0.69 mol H2/mol T-sugar was 1.5 times higher than that in the batch mode while the hydrogen production rate was 10 ± 1.17 L/d/L. The presence of bacteria Clostridium pasteurianum which favours the production of hydrogen from of acetic acid and butyric acid was determined by DGGE. [ABSTRACT FROM AUTHOR]