Multistage wet lipid extraction from fresh water stressed Neochloris oleoabundans slurry – Experiments and modelling

Algae are considered an important renewable feedstock for lipid extraction to produce biofuels. Algae strain Neochloris oleoabundans used in this research can yield a high lipid content under stressed conditions. N-ethyl butylamine (EBA) as a switchable solvent has previously shown outstanding performance on energy efficient lipid extraction from non-broken wet algae slurry. In this work, a model was developed that describes the equilibrium state of lipid extraction from fresh water (FW)-stressed Neochloris oleoabundans algae slurry using EBA as solvent. When assuming that the cell interior is almost completely filled with the solvent phase during extraction, the model estimated extraction yields showed good agreement with those obtained in experiments. The developed model can predict the amount of crude lipid being recovered from any stage of a multistage extraction process

Microalgae wet extraction using N-ethyl butylamine for fatty acid production

AbstractMicroalgae are considered a promising feedstock for the production of food ingredients, cosmetics, pharmaceutical products and biofuels. The energy intensity of drying and cell breaking of algae and solvent recovery afterwards hindered the route of algae biorefinery. In this work the influences of freeze drying and cell breaking to the extraction efficiency of crude lipid yield and fatty acid yield were investigated. Results showed that drying and cell breaking are not necessary for N-ethyl butylamine extraction, because good yields were obtained without. Crude lipid yield and fatty acid yield using N-ethyl butylamine were comparable with Bligh & Dyer extraction, making N-ethyl butylamine a candidate for further development of an energy efficient lipid extraction technology for non-broken microalgae

Pyrolysis of plastic waste: effect of feedstock pretreatment and fate of contaminants

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Furfural to Cyclopentanone – a Search for Putative Oligomeric By-products

We report here on the reductive rearrangement of biomass-derived furfural to cyclopentanone, a promising non-fossil feedstock for fuels and chemicals. An underreported aspect of this reaction is the inevitable formation of heavy byproducts. To mitigate its formation, process condition such as, solvent, catalyst, temperature, acidity, and feed concentration were varied to unravel the chemistry and improve the reaction performance. Water medium was confirmed to play a crucial role, as organic solvents were unable to deliver cyclopentanone or heavy by products. Copper-based catalyst showed the highest selectivity for ring-rearrangement, reaching 50 mol % under the conditions investigated. The main factor influencing the yields of cyclopentanone (CPO), and promote oligomer formation, are the feed concentration and the pH, as high feed concentrations and high acidity facilitate the self-polymerization of furfuryl alcohol (FALC). This was confirmed by dedicated experiments using FALC and the hydroxypentenone intermediate as feed. The concentration challenge could be mitigated by slowly dosing the feed, which increased the desired product yields by 4–12 mol %. Nevertheless, most oligomers appeared to fall in the range of common liquid fuels and could be converted to diesel by hydrodeoxygenation.</p

Analysis of the energy consumption of supercritical water desalination (SCWD)

An experimental and modelling study was done to investigate supercritical water desalination (SCWD) with respect to energy consumption as a function of the NaCl concentration (0 to 20 wt%). Pilot plant experiments were performed for different flow rates and feed concentrations, and used for the validation of the thermodynamic models (eNRTL and Anderko & Pitzer) employed for phase equilibria and enthalpy calculations. Experimental and modelling results showed that the lowered heat capacity of the feed streams, while increasing the concentration from 0 to 7 wt%, leads to improved performance of the feed - supercritical water (SCW) heat exchanger (HEX), evident from a higher feed outlet temperature. For concentrations of ≥14 wt%, pre-heating of the feed, prior to the HEX, is recommended due to the decrease in the SCW recovery in the SCW-brine separator. The calculated duty, of the heater bringing the heat-exchanged feed to the separation temperature, decreases with NaCl concentration due to the decrease in the feed heat capacity. The calculated overall energy consumption of SCWD was between 0.71 and 0.90 MJth/kgfeed. For higher concentration feeds, the energy input is divided between low – and high quality (temperature) heat

Influence of pulping conditions on the pulp yield and fiber properties for pulping of spruce chips by deep eutectic solvent

The chemical pulping of wood chips using deep eutectic solvents (DES-pulping) has emerged as an alternative technology to conventional pulping in the paper industry, allowing the production of pulp in combination with the recovery of lignin and sugars for valorization. A challenge in the development of this technology is the understanding of how the operating conditions influence the crucial pulp manufacturing parameters such as delignification percentage, pulp yield, and fiber quality. This work is focused on investigating the effect of operating conditions such as cooking temperature, cooking time, liquor-to-wood ratio, initial water content on DES, type of mixing, the addition of a pre-treatment step (pre-impregnation of DES into the wood chips) to cooking process, and DES composition (lactic acid:choline chloride, lactic acid:sodium chloride, and lactic acid:sodium bromide) on the cooking of wood chips by DES. A shortcut quality evaluation parameter (Q), defined as the product of the fiber length and the degree of delignification quantified the quality of the pulping process in a single value, shows values similar to a reference unbleached kraft pulp for cooking at 130 °C in a range of cooking times from 3 to 4.5 h at a L/W of 10:1 by using lactic acid:choline chloride DES. More elaborate property analysis on the fibers showed that several of the the quality-indicating properties of the fibers (coarseness, shape factor, fibril area, and crill index) are comparable with typical sulfite pulping fibers.</p

Design and results of a first generation pilot plant for supercritical water desalination (SCWD)

A pilot plant of 5 kg/h based on the principle of supercritical water desalination (SCWD) has been designed, built and operated. The detailed design, operating procedures and performance of the plant is presented in this paper, along with the first results. Firstly, the plant has been tested for feed streams of 3.5 wt% NaCl to evaluate the stability and repeatability of the system, with the results indicating that mass balance closure is good and that reproducible results can be obtained. Furthermore, the results showed that 93% of the feed is recovered as fresh drinking water, which corresponds with expected results from phase equilibria simulations. The plant was further tested for higher feed concentrations of up to 16 wt% NaCl. For all feed concentrations, the NaCl concentration of the SCW was that of drinking water quality (< 600 ppm). Experimentally, using a single stage separator, a concentrated brine (38 wt% NaCl) was obtained and calculations showed that with a two-stage flash-evaporation scheme, zero liquid discharge (ZLD) can be obtained. Further modifications to the plant and tests with other salt mixtures are recommended in order to advance to industrial application