Energy balance and life cycle assessments in producing microalgae biodiesel via a continuous microalgal-bacterial photobioreactor loaded with wastewater.

Life cycle assessments of microalgal cultivation systems are often conducted to evaluate the sustainability and feasibility factors of the entire production chain. Unlike widely reported conventional microalgal cultivation systems, the present work adopted a microalgal-bacterial cultivation approach which was upscaled into a pilot-scale continuous photobioreactor for microalgal biomass production into biodiesel from wastewater resources. A multiple cradle-to-cradle system ranging from microalgal biomass-to-lipid-to-biodiesel was evaluated to provide insights into the energy demand of each processes making up the microalgae-to-biodiesel value chain system. Energy feasibility studies revealed positive NER values (4.95-8.38) for producing microalgal biomass but deficit values for microalgal-to-biodiesel (0.14-0.23), stemming from the high energy input requirements in the downstream processes for converting biomass into lipid and biodiesel accounting to 88-90% of the cumulative energy demand. Although the energy balance for microalgae-to-biodiesel is in the deficits, it is comparable with other reported biodiesel production case studies (0.12-0.40). Nevertheless, the approach to using microalgal-bacterial cultivation system has improved the overall energy efficiency especially in the upstream processes compared to conventional microalgal cultivation systems. Energy life cycle assessments with other microalgal based biofuel systems also proposed effective measures in increasing the energy feasibility either by utilizing the residual biomass and less energy demanding downstream extraction processes from microalgal biomass. The microalgal-bacterial cultivation system is anticipated to offer both environmental and economic prospects for upscaling by effectively exploiting the low-cost nutrients from wastewaters via bioconversion into valuable microalgal biomass and biodiesel.

Cobalt nanoparticle supported on layered double hydroxide: Effect of nanoparticle size on catalytic hydrogen production by NaBH4 hydrolysis.

Catalytic hydrolysis of sodium borohydride (NaBH4) is a promising method to provide clean hydrogen (H2) energy for portable devices. Therefore, designing a non-noble metal catalyst that performs well in this hydrolysis is essential. Cobalt-nanoparticles (Co-NPs) supported on magnesium-aluminium layered double hydroxide (LDH) with various mean diameter were synthesized by changing concentration of cobalt-citrate anion (Co-citrate) precursor used for ion exchange with the LDH host. Then the Co-citrate intercalated LDHs were reduced with NaBH4 to form Co-NPs. Evidence of successful intercalation was shown by X-ray diffraction (XRD) and Fourier-Transform Infrared spectroscopy (FT-IR). Transmission Electron Microscope (TEM) and Scanning TEM (STEM) observations revealed that Co-NPs were in metallic state and their mean diameter increased with the concentration of Co-citrate solution. Nitrogen physisorption isotherms showed that the surface structure of LDHs transformed from non-porous to mesoporous after chemical reduction, which indicated that the Co-NPs were formed in the interlayer of LDHs. Catalytic hydrolysis of NaBH4 at 25 °C clarified that the catalyst synthesized from 6 mM Co-citrate solution showed the highest H2 generation rate of 4520 ± 251 mL min-1·gCo-1, indicating the catalyst had the optimum size of Co-NP. This activity could be considered relatively higher compared to unsupported cobalt and many other supported cobalt-base catalysts previously reported. It was also clearly shown that size of Co-NPs supported on LDH could be a significant parameter as it allowed better accessibility of reactants to the active catalyst surface to obtain maximum activity. For this optimum catalyst, the activation energy was evaluated to be 56.9 kJ mol-1. Although the catalyst was able to achieve almost the same conversion when the catalyst was repeatedly tested five times under the same condition, the catalytic activity decreased gradually. Overall, it could be revealed that Co-NPs supported on LDHs have a huge potential to be used for H2 energy production.

In-situ catalytic upgrading of bio-oil from rapid pyrolysis of biomass over hollow HZSM-5 with mesoporous shell.

To solve the issue of narrow micropores in traditional protonic type Zeolite Socony Mobil-5 (HZSM-5) catalysts in the restricting of large-molecular reactants/products diffusion, hollow HZSM-5 with a mesoporous shell was prepared using a hydrothermal method combined with a tetrapropylammonium hydroxide (TPAOH) treatment process. Applying for in-situ catalyst upgrading of bio-oil from rapid pyrolysis of biomass, the obtained most efficient catalyst of Hollow(30)-TP resulted in aromatic hydrocarbon yields in the range of 78.49-78.67% for cellulose and hemicellulose, which is much greater than those using the traditional HZSM-5 (61.06-68.26%). Furthermore, in the case using real biomass (cedar) with an optimal biomass/catalyst weight ratio of 1:2, the aromatic hydrocarbon yield reached up to 80.16%. In addition, this catalyst exhibited excellent reusability and regeneration property due to the increased accessibility to the acid sites in the hollow HZSM-5 for the improving of the reaction rate as well as the reducing of coking.

Penetration Process of a Hydrated Deep Eutectic Solvent Through the Stratum Corneum and its Application as a Protein Penetration Enhancer.

The penetration mechanism of choline chloride-glycerol deep eutectic solvent (DES) through the stratum corneum (SC) as a potential solvent for a novel enhancer of protein penetration into the skin was investigated in a wide and small angle X-ray diffraction study. We found that DES penetrated through intercellular lipids but not the corneocytes. DES seemed to extract a portion of lipids of the short lamellae in the SC. Hydrated DES with a DES to water weight ratio of 9 to 1 (9DES-1H2O) showed the strongest interaction with the lipids in the SC compared with water, DES, and hydrated DESs with another weight ratio of DES to water (DES : water=8 : 2). In a skin penetration test with a fluorescently labelled lysozyme, 9DES-1H2O increased the amount of penetration through the SC by two-fold compared with HEPES buffer.

Deep Eutectic Solvent-Induced Structural Transition of Microemulsions Explored with Small-Angle X-ray Scattering.

Microemulsions (MEs) containing deep eutectic solvents (DESs) and water in the inner phase for use in transdermal delivery of poorly soluble drugs were prepared using a mixture of polyoxyethylene sorbitan monooleate (Tween-80) and sorbitan laurate (Span-20) as surfactants. We investigated the effects of the ratios of surfactant (Tween-80/Span-20) and solvents (DES components/water) on the ME structure determined by the analysis of small-angle X-ray scattering profiles with the core-corona model. Tween-80 with an unsaturated long alkyl chain induced a structural transition of MEs from a sphere to a cylinder. DESs caused the aggregation of surfactants due to the solvophobic interactions between DESs and the alkyl chains of surfactants. Transmittance electron microscopy images of MEs indicated the presence of aggregates of the dispersed ME particles with each shape.

HPMA copolymer conjugate with pirarubicin: In vitro and ex vivo stability and drug release study.

We have developed a tumor environment-responsive polymeric anticancer prodrug containing pirarubicin (THP) conjugated to N-(2-hydroxypropyl) methacrylamide copolymer (PHPMA), [P-THP], through a spacer containing pH-sensitive hydrazone bond, that showed remarkable therapeutic effect against various tumor models and in a human pilot study. Toward clinical development, here we report THP release profile from its HPMA copolymer conjugate, the conjugate stability, protein and cell-binding and solubility of P-THP. Size exclusion chromatography of P-THP (molecular weight 38 kDa) showed similar hydrodynamic volume as bovine serum albumin (BSA) in aqueous solution, with no apparent interactions with BSA, nor aggregation by itself. pH-responsive release of free THP was reconfirmed at pHs 6.5 and lower. The drug release was significantly affected by a type of used buffer. Phosphate buffer seems to facilitate faster hydrazone bond cleavage at pH 7.4 whereas higher stability was achieved in L-arginine solution which yielded only little cleavage and THP release, approx. 15% within 2 weeks at the same pH at 25 °C. Furthermore, ex vivo study using sera of different animal species showed very high stability of P-THP. Incubation with blood showed high stability of P-THP during circulation, without binding to blood cells. These findings revealed that L-arginine solution provides appropriate media for formulation of P-THP infusion solution as tumor-targeted polymeric anticancer drug based on EPR effect.

Steam reforming of tar derived from lignin over pompom-like potassium-promoted iron-based catalysts formed on calcined scallop shell.

In order to understand the improvement effect of potassium (K) on the catalytic activity of iron-loaded calcined scallop shell (CS) for the steam reforming tar derived from biomass, various K precursors were applied for the catalyst preparation. It is found that pompom-like iron-based particles with a mesoporous structure were easily formed on the surface of calcined scallop shell (CS) when K2CO3 was used as K precursor while no such kind of microsphere was formed when other kinds of K precursors such as KOH and KNO3 were applied. The optimum K-loading amount for the preparation of this catalyst was investigated. Based on the experimental results obtained, a mechanism for the formation of these microspheres was proposed. This pompom-like potassium-promoted iron-based catalyst showed a better catalytic activity and reusability for the steam reforming of tar derived from lignin.

Esterification of oleic acid in a three-phase, fixed-bed reactor packed with a cation exchange resin catalyst.

Esterification of oleic acid was performed in a three-phase fixed-bed reactor with a cation exchange resin catalyst (Amberlyst-15) at high temperature, which was varied from 80 to 120 °C. The fatty acid methyl ester (FAME) yields in the fixed-bed reactor were increased with increases in the reaction temperature, methanol flow rate and bed height. Moreover, the FAME yields were higher than those obtained using a batch reactor due to an equilibrium shift toward the product that resulted from continuous evaporation of the produced water. In addition, there was no catalyst deactivation during the esterification of oleic acid. However, addition of sunflower oil to the oleic acid reduced the FAME yield obtained from simultaneous esterification and transesterification. The FAME yield was 97.5% at a reaction temperature of 100 °C in the fixed-bed with a height of 5 cm when the methanol and oleic acid feed rates were 8.6 and 9.0 mL/h, respectively.