In this study, we present the activities of Al₂O₃ supported CaO and MgO catalysts in the transesterification of lipid of yellow green microalgae, Nannochloropsis oculata, as a function of methanol ...amount and the CaO and MgO loadings at 50°C. We found that pure CaO and MgO were not active and CaO/Al₂O₃ catalyst among all the mixed oxide catalysts showed the highest activity. Not only the basic site density but also the basic strength is important to achieve the high biodiesel yield. Biodiesel yield over 80wt.% CaO/Al₂O₃ catalyst increased to 97.5% from 23% when methanol/lipid molar ratio was 30.
A main shift in the competitive landscape of technology development is in 3D printing of complex articles made of variety of materials due to faster manufacturing and less human error in the ...production. In fact, it seems to be a viable candidate for the construction of structures for terrestrial and extraterrestrial life in future. Thus, new or damaged equipment in space explorations could be replaced instantly, and habitats could be manufactured using 3D printing in varying gravitational fields in the solar system. Among 3D printing materials, HDPE is commonly used in the projects, such as a prototype manufacturing or pipes or damp-proof membrane. This study initially focused on the preliminary design of the self-sustaining mini ethylene production plant from Martian atmosphere with scale-out architecture. UniSIM® was integrated with MATLAB® via CAPE-OPEN extension to design mini-ethylene production plant at low gravity. Ethylene capacity was found as 17.71 tons/year for 100 modules.
In this study, we present the ethyl esters biodiesel production from Nannochloropsis oculata and Spirulina sp. microalgal lipids on 60 wt% CaO on Al2O3 catalyst at 50 °C and 1.0 atm. The activity of ...the catalyst was studied as a function of ethanol:lipid molar ratios, catalyst amounts and reaction times. It was found that 6 wt% of the lipids as catalyst amount resulted in 59% biodiesel yield in 30 min at 12 of ethanol:lipid molar ratio whereas 90–99% biodiesel yield was obtained at 24 and 48 of ethanol:lipid molar ratios. In order to achieve 90–99% yields, the basic strength was found to be weak and to be in the form of bicarbonate, whereas high basicity was not necessary. Besides, pure CaO and Al2O3 were not active under the same reaction conditions. We found that the glycerolysis of triacylglyceride occurred in series with the reverse of the transesterification of the triacylglyceride when the catalyst amount was 6 wt% of the lipids and the ethanol:lipid molar ratio was 24 and 48 and the reaction time was 60 min.
•Ethyl ester biodiesel from marine N. oculata and Spirulina sp. on solid catalyst.•>90% biodiesel yield production on 60%CaO/Al2O3 catalyst in 30 min at 50 °C under ethanol:lipid ratios ranging from 12 to 48.•High activity related to bicarbonate like basic strength of the catalyst.
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•Biodiesel was produced using PES membrane immobilized with alumina-calcium oxide.•Biodiesel yield declined in the first three cycles and then remained constant.•Antifouling membrane ...surface allowed recovering yield through butanol backwashing.•After 30 days of storage in reaction mixture, biodiesel yield did not change.•Antifouling catalytic membranes contribute to sustainable biodiesel production.
Biodiesel is an alternative biofuel that can be blended with conventional petroleum-derived diesel fuel to partly reduce the dependence on the imported oil. Catalytic membrane reactors are promising candidates for sustainable biodiesel production. Herein, we report a novel catalytically active polydopamine-modified poly (ether sulfone) (PES) membrane immobilized with an alumina-calcium oxide catalyst. The reaction temperature, butanol to canola oil ratio, and transmembrane pressure applied through the membrane were optimized with response surface methodology and Box–Behnken design. In contrast to all previous catalytic membrane studies for biodiesel production, we used butanol as a co-reactant to improve the winter problems of biodiesel made with methanol. FTIR and SEM-EDX analysis confirmed the successful immobilization of the catalyst. At the end of 30 days of storage in the reactant mixture, 95% of the catalyst loaded to the membrane was still on the surface, and biodiesel yield values and butanol flux of the membrane did not change. We compared the batch and flow-through operation modes by measuring the catalytic activity of membranes under static and dynamic conditions within 24 h (8-cycle). The biodiesel yield under dynamic condition decreased in the first three cycles from 54.54 ± 0.65% to 47.31 ± 0.70% and then stayed constant, whereas a continuous decrease from 25.42 ± 0.57% to 17.19 ± 0.58% was observed under static condition. In each cycle, the equilibrium limitation for the yield was overcome only when the membrane was operated under pressure. The main reason for the decrease in catalytic activities was the fouling on the catalyst surface which was quickly removed by backwashing with butanol. It is concluded that catalytic membranes with antifouling properties and alcohol stability can make biodiesel production more cost-effective and environmentally friendly.
Under optimal process conditions, pyrolysis of polyolefins can yield ca. 90 wt % of liquid product, i.e., combination of light oil fraction and heavier wax. In this work, the experimental findings ...reported in a selected group of publications concerning the non-catalytic pyrolysis of polyolefins were collected, reviewed, and compared with the ones obtained in a continuously operated bench-scale pyrolysis reactor. Optimized process parameters were used for the pyrolysis of waste and virgin counterparts of high-density polyethylene, low-density polyethylene, polypropylene and a defined mixture of those (i.e., 25:25:50 wt %, respectively). To mitigate temperature drops and enhance heat transfer, an increased feed intake is employed to create a hot melt plastic pool. With 1.5 g·min
−1
feed intake, 1.1 L·min
−1
nitrogen flow rate, and a moderate pyrolysis temperature of 450 °C, the formation of light hydrocarbons was favored, while wax formation was limited for polypropylene-rich mixtures. Pyrolysis of virgin plastics yielded more liquid (maximum 73.3 wt %) than that of waste plastics (maximum 66 wt %). Blending polyethylenes with polypropylene favored the production of liquids and increased the formation of gasoline-range hydrocarbons. Gas products were mainly composed of C
3
hydrocarbons, and no hydrogen production was detected due to moderate pyrolysis temperature.
► CaO/Al
2O
3 single step sol–gel made catalysts for sunflower transesterification. ► Sunflower transesterification at 50
°C. ► Basicity and basic strength using CO
2 temperature programmed ...desorption. ► Volcano plot using turnover frequency and basic strength. ► High turnover frequency does not mean high biodiesel yield at 50
°C. ► 60% CaO/Al
2O
3 has high TOF, 0.028
s
−1, but low biodiesel yield, ∼80%.
The activities of single step sol–gel made calcium oxide on alumina catalysts were studied as a function of CaO loading, methanol/oil molar ratio and the amount of the catalyst in the transesterification of sunflower oil at 50
°C. Also, the turnover frequency (TOF) of the catalysts was calculated to better understand the relationship between the basicity/basic strength and the catalytic activity. From volcano curve (TOF vs. basic strength), it was found that under 50
°C and methanol/oil molar ratio of 9, 60% CaO/Al
2O
3 had the highest turnover frequency, 0.028
s
−1, whereas 85% CaO/Al
2O
3 showed the highest biodiesel yield, ∼96.6%, but TOF obtained on it was 0.012
s
−1. It seemed that 60% CaO catalyst had the proper basic strength to obtain the highest TOF.
The activities of single step sol-gel made calcium oxide on alumina catalysts were studied as a function of CaO loading, methanol/oil molar ratio and the amount of the catalyst in the ...transesterification of sunflower oil at 50°C. Also, the turnover frequency (TOF) of the catalysts was calculated to better understand the relationship between the basicity/basic strength and the catalytic activity. From volcano curve (TOF vs. basic strength), it was found that under 50°C and methanol/oil molar ratio of 9, 60% CaO/Al(2)O(3) had the highest turnover frequency, 0.028s(-1), whereas 85% CaO/Al(2)O(3) showed the highest biodiesel yield, ∼96.6%, but TOF obtained on it was 0.012s(-1). It seemed that 60% CaO catalyst had the proper basic strength to obtain the highest TOF.
Silver-containing antibacterial membranes are commonly used to control biofouling during bacteria filtration. Unfortunately, fast and uncontrolled release of silver to water is a challenge since this ...causes mass accumulation of silver in water resources and insufficient long-term antimicrobial effect. To overcome these disadvantages, we propose to add AgCl-TiO2 xerogels (0–0.8 wt%) in the polyacrylonitrile membranes. The long-term silver retaining of the membranes was evaluated by measuring the silver release under filtration of deionized water in the absence and the presence of 1 M NaCl up to 5 days. The antibiofouling and the antibacterial efficacies were determined by measuring the changes in antibacterial activity and DI water flux of the membranes at the end of 5 days of E. coli filtration. The 0.2 wt% AgCl-TiO2 xerogel incorporated polyacrylonitrile membrane demonstrated a constant ~1 μg of silver release/cm2 per filtration cycle after a total filtration of 0.05 L/cm2 with 1 M NaCl solution. Additionally, it showed antibacterial efficacy and ~100% recovery of deionized water flux by simple backwashing with water after having been used in many E. coli filtration cycles. Thus, this membrane could potentially be used up to ~5.8 years for 8000 h a year for the filtration of high salinity water.
Silver-containing antibacterial membranes are commonly used to control biofouling during bacteria filtration. Uncontrolled release of silver from the membrane causes massive silver accumulation in water which in turn leads to contamination of water resources and threat to aquatic organisms. Although silver release is strongly influenced by the salinity of water, the release data was collected through filtration of pure DI water or tap water in literature. To overcome the shortcomings of the published studies, we propose to use AgCl-TiO2 xerogels in membranes due to low solubility of AgCl in water and measure the release by filtering high-salinity water.
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•Polyacrylonitrile membranes incorporated with AgCl-TiO2 xerogels were developed.•0.2 wt% AgCl-TiO2 in the membranes provided a significant antibiofouling property.•The long-term release of silver ions was tested using 1 M NaCl and deionized water.•Sustained silver release was achieved at high NaCl concentrations.•0.2%AgCl-TiO2 xerogel could provide membrane ~5.8 years × 8000 h/year lifetime.
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