Extraction and separation of astaxanthin with the help of pre-treatment of Haematococcus pluvialis microalgae biomass using aqueous two-phase systems based on deep eutectic solvents

The microalgae Haematococcus pluvialis are the main source of the natural antioxidant astaxanthin. However, the effective extraction of astaxanthin from these microalgae remains a significant challenge due to the rigid, non-hydrolyzable cell walls. Energy savings and high-efficiency cell disruption are essential steps in the recovery of the antioxidant astaxanthin from the cysts of H. pluvialis. In the present study, H. pluvialis microalgae were first cultured in Bold's Basal medium under certain conditions to reach the maximum biomass concentration, and then light shock was applied for astaxanthin accumulation. The cells were initially green and oval, with two flagella. As the induction time increases, the motile cells lose their flagellum and become red cysts with thick cell walls. Pre-treatment of aqueous two-phase systems based on deep eutectic solvents was used to decompose the cell wall. These systems included dipotassium hydrogen phosphate salt, water, and two types of deep eutectic solvents (choline chloride-urea and choline chloride-glucose). The results of pre-treatment of Haematococcus cells by the studied systems showed that intact, healthy cysts were significantly ruptured, disrupted, and facilitated the release of cytoplasmic components, thus facilitating the subsequent separation of astaxanthin by liquid-liquid extraction. The system containing the deep eutectic solvent of choline chloride-urea was the most effective system for cell wall degradation, which resulted in the highest ability to extract astaxanthin. More than 99% of astaxanthin was extracted from Haematococcus under mild conditions (35% deep eutectic solvent, 30% dipotassium hydrogen phosphate at 50 °C, pH = 7.5, followed by liquid-liquid extraction at 25 °C). The present study shows that the pre-treatment of two-phase systems based on deep eutectic solvent and, thus, liquid-liquid extraction is an efficient and environmentally friendly process to improve astaxanthin from the microalgae H. pluvialis.

Carbon-Based Nanostructures as Emerging Materials for Gene Delivery Applications

Gene therapeutics are promising for treating diseases at the genetic level, with some already validated for clinical use. Recently, nanostructures have emerged for the targeted delivery of genetic material. Nanomaterials, exhibiting advantageous properties such as a high surface-to-volume ratio, biocompatibility, facile functionalization, substantial loading capacity, and tunable physicochemical characteristics, are recognized as non-viral vectors in gene therapy applications. Despite progress, current non-viral vectors exhibit notably low gene delivery efficiency. Progress in nanotechnology is essential to overcome extracellular and intracellular barriers in gene delivery. Specific nanostructures such as carbon nanotubes (CNTs), carbon quantum dots (CQDs), nanodiamonds (NDs), and similar carbon-based structures can accommodate diverse genetic materials such as plasmid DNA (pDNA), messenger RNA (mRNA), small interference RNA (siRNA), micro RNA (miRNA), and antisense oligonucleotides (AONs). To address challenges such as high toxicity and low transfection efficiency, advancements in the features of carbon-based nanostructures (CBNs) are imperative. This overview delves into three types of CBNs employed as vectors in drug/gene delivery systems, encompassing their synthesis methods, properties, and biomedical applications. Ultimately, we present insights into the opportunities and challenges within the captivating realm of gene delivery using CBNs.

A comparative study of deep eutectic solvents based on fatty acids and the effect of water on their intermolecular interactions

In this work, intermolecular interactions among the species of fatty acids-based DESs with different hydrogen bond acceptors (HBA) in the adjacent water have been investigated using molecular dynamics (MD) simulation. The results of this work provide deep insights into understanding the water stability of the DESs based on thymol and the eutectic mixtures of choline chloride and fatty acids at a temperature of 353.15 K and atmospheric pressure. Stability, hydrogen bond occupancy analysis, and the distribution of the HBA and HBD around each other were attributed to the alkyl chain length of FAs and the type of HBA. Assessed structural properties include the combined distribution functions (CDFs), the radial distribution functions (RDFs), the angular distribution functions (ADFs), and the Hydrogen bonding network between species and Spatial distribution functions (SDF). The reported results show the remarkable role of the strength of the hydrogen bond between THY molecules and fatty acids on the stability of DES in water. The transport properties of molecules in water-eutectic mixtures were analyzed by using the mean square displacement (MSD) of the centers of mass of the species, self-diffusion coefficients, vector reorientation dynamics (VRD) of bonds and the velocity autocorrelation function (VACF) for the center of the mass of species.

Effect of water addition on caprylic acid: Quaternary ammonium salts (QAS) deep eutectic solvents: Characterization of their structural and dynamical properties

Physicochemical properties of the binary mixtures based on Caprylic acid: Quaternary ammonium salts (QAS) (7:3 mol ratio) are investigated using MD simulations. Considering the hydrophobic character of eutectic solvents based on long-chain fatty acids, the stability of the binary mixtures was investigated in the adjacent water. In order to investigate the effect of water on intermolecular interactions in binary mixtures, the structural properties of the binary mixtures in the pure state and adjacent to water were investigated at 310 K. Assessed structural properties include the combined distribution functions (CDFs), the radial distribution functions (RDFs), the angular distribution functions (ADFs), and the Hydrogen bonding network between HBA and HBD and Spatial distribution functions (SDF). We aimed to represent the structural stability of eutectic solvents based on Caprylic acid and Quaternary ammonium salts (QAS) as a function of the alkyl chain length of cations, the evidence was found for the interaction between the chloride anion leads to the transition of HBA to the water-rich phase. The alkyl chain length of cations of Quaternary ammonium salts shows the stability of eutectic solvents in the adjacent water.

Rheological and thermal properties of an enteral nutrition formula for nutritional support patients using a combined mixture of gelatin and maltodextrin

Enteral nutrition is a type of nutritional support that provides the necessary sources of energy and protein for patients who suffer from dysphagia, chronic disease, and loss of appetite. In this study, a gelatin-maltodextrin binary biopolymer system has been incorporated into a semi-solid formula. The I-optimal combination design approach was used to create 19 formulations, and the dynamic rheological properties, dynamic laser scattering, and zeta potential responses were evaluated over 30 days of storage at 5°C. Solid viscoelastic behavior has been approved since G' > G″ in the frequency sweep test with no cross-over point. Maltodextrin may interfere within the gelatin network, and increasing the maltodextrin to gelatin (from 0.14 to 1) may lead to a wider linear viscoelastic (LVE) strain range (2.16%), a lower storage modulus at LVE (52%), a lower yield stress (46%), and a lower glass transition temperature (34%). The presence of maltodextrin may reduce the temperature of the sol-to-solid transformation by 48% and enhance its flexibility. In contrast, increasing the gelatin-to-maltodextrin ratio following melting at 37°C led to an increase in the cumulant mean and polydispersity index, indicating a relatively unstable system. The range of zeta potential values between -4.4 and 1.7 mV confirmed a tendency toward coagulation. Microscopic images revealed instability because of irregular or compact chains formed in the gelatin matrix by using higher amounts of maltodextrin. Finally, the best formula had the best rheological stability and was suitable for tube-feeding patients, with a gelatin-to-maltodextrin ratio of 4.35:3.64% w/w on day 17.4.

Pathogenic CANVAS-causing but not nonpathogenic RFC1 DNA/RNA repeat motifs form quadruplex or triplex structures

Biallelic expansions of various tandem repeat sequence motifs are possible in RFC1 (replication factor C subunit 1), encoding the DNA replication/repair protein RFC1, yet only certain repeat motifs cause cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS). CANVAS presents enigmatic puzzles: The pathogenic path for CANVAS neither is known nor is it understood why some, but not all expanded, motifs are pathogenic. The most common pathogenic repeat is (AAGGG)n•(CCCTT)n, whereas (AAAAG)n•(CTTTT)n is the most common nonpathogenic motif. While both intronic motifs can be expanded and transcribed, only r(AAGGG)n is retained in the mutant RFC1 transcript. We show that only the pathogenic forms unusual nucleic acid structures. Specifically, DNA and RNA of the pathogenic d(AAGGG)4 and r(AAGGG)4 form G-quadruplexes in potassium solution. Nonpathogenic repeats did not form G-quadruplexes. Triple-stranded structures are formed by the pathogenic motifs but not by the nonpathogenic motifs. G- and C-richness of the pathogenic strands favor formation of G•G•G•G-tetrads and protonated C+-G Hoogsteen base pairings, involved in quadruplex and triplex structures, respectively, stabilized by increased hydrogen bonds and pi-stacking interactions relative to A-T Hoogsteen pairs that could form by the nonpathogenic motif. The ligand, TMPyP4, binds the pathogenic quadruplexes. Formation of quadruplexes and triplexes by pathogenic repeats supports toxic-DNA and toxic-RNA modes of pathogenesis at the RFC1 gene and the RFC1 transcript. Our findings with short repeats provide insights into the disease specificity of pathogenic repeat motif sequences and reveal nucleic acid structural features that may be pathogenically involved and targeted therapeutically.

Assessment of the properties of natural-based chiral deep eutectic solvents for chiral drug separation: insights from molecular dynamics simulation

The structural and physicochemical properties of chiral deep eutectic solvents (DESs) consisting of racemic mixtures of menthol and acetic acid (DES1), racemic mixtures of menthol and lauric acid (DES2), and racemic mixtures of menthol and pyruvic acid (DES3) for enantioselective extraction processes are investigated. Structural results, such as the radial distribution function (RDF) and the combined distribution function (CDF), indicate that the hydroxyl hydrogen of menthol has a dominant interaction with the carbonyl oxygen of the acids in the considered DESs. The number of hydrogen bonds and non-bonded interaction energies formed between S-menthol and HBDs are larger than those with R-menthol, resulting in the self-diffusion coefficient of S-menthol being larger than that of R-menthol. Therefore, it can be said that the proposed DESs are good candidates for the separation of drugs with S chirality. The effects of acid type on the density and isothermal compressibility of DESs show the behaviour of DES2 > DES3 > DES1 and DES1 > DES3 > DES2, respectively. Our results provide a better perspective on new chiral DESs at the molecular level for enantioselective processes.

Investigation the effect of water addition on intermolecular interactions of fatty acids-based deep eutectic solvents by molecular dynamics simulations

In this work, we focused on the interaction between hydrogen bond acceptor (HBA) and hydrogen bond doner (HBD) in the binary mixtures. The results showed that Cl^- anion plays a key role in the formation of DESs. Also, the structural stability of deep eutectic solvents based on fatty acids (FAs) and choline chloride (Ch⁺Cl^-) at different ratios was investigated in water using molecular dynamics simulations. We observed that the interaction between the chloride anion and the hydroxyl group of the cation leads to the transition of HBA to the water-rich phase. These atomic sites have important rule in the stability of the eutectic mixtures based on FAs and Cl^- anion. However, it seems that the binary mixtures with the mole percent at 30% of [Ch⁺Cl^-] and 70% of FAs have more stability than other ratios.

Measurement of thermodynamic properties, including volumetric, sonic, and viscometrical properties, of aqueous solutions containing polyethylene glycol and erythromycin at 293.15, 303.15, and 313.15 K

In this study, the interactions in aqueous binary and ternary systems containing polyethylene glycol (6000) and erythromycin at different temperatures were investigated to utilize this information in the aqueous two-phase method for different purposes, including separation and purification. Through experimental methods, density, sound velocity, and viscosity at 293.15, 303.15, and 313.15 K were measured in aqueous solutions, including erythromycin and polyethylene glycol. From the experimental density data, apparent molar volume (ϕ V), limiting apparent molar volume (ϕ V 0) and transfer molar volume ( ∆ t r ϕ V 0 ) ${{\increment}}_{\mathrm{t}\mathrm{r}}{\phi }_{\mathrm{V}}^{0})$ have been calculated. Also, the experimental sound velocity data determined apparent molar isentropic compressibility (ϕ k), limiting apparent molar isentropic compressibility (ϕ k 0) and transfer isentropic compressibility ( ∆ tr ϕ k 0 ) ${{\increment}}_{\mathrm{tr}}{\phi }_{\mathrm{k}}^{0})$ values of polyethylene glycol (6000) from water to erythromycin solutions. Furthermore, experimental viscosity data and the Jones–Dole equation determined viscosity β ′-coefficient and transfer viscosity β ′-coefficient ( ∆ t r β ′ ) ${{\increment}}_{\mathrm{t}\mathrm{r}}{\beta }^{\prime })$ values. The obtained results investigated the polymer effect as kosmotropic or chaotropic on erythromycin drug and the interaction between polyethylene glycol and erythromycin (solute-solute interactions). The results show that the interaction between drug and polymer is more desirable in the high-concentration polymer. Finally, results indicate that polyethylene glycol (6000) has played a kosmotropic role in aqueous solutions of erythromycin.

Investigation of novel passive methods of generation of swirl flow in supersonic separators by the computational fluid dynamics modeling

In this paper, three passive methods for the generation of swirl flow in the supersonic separator (3S) were investigated, and their structures were optimized by computational fluid dynamics (CFD) modeling. The influence of the structural and operational parameters on the dew point depression, phase envelope diagram, rate of natural gas liquid (NGL) recovery, and separation efficiency have also been evaluated. The collection efficiency was significantly improved for the nozzle equipped with the passive swirler compared with the simple nozzle. The selection of passive swirler type played a crucial role in the natural gas liquefaction and separation. The side injected swirler, and serpentine swirler showed the most significant improvement in separation efficiency than the U-turn swirler. For the side injected swirler at the optimum injection angle, the maximum collection efficiency was about 89% at the pressure loss ratio (PLR) of 0.2. Besides, the simulation results demonstrated that for the serpentine 3S, with the increase in serpentine twist number, the highest improvement on the collection efficiency of the investigated nozzle was obtained. In addition, it was observed that, when the convergent section profile was designed according to the Witoszynski line-type, a larger refrigeration zone was obtained than other considered profiles.

Stimuli-Responsive Miktoarm Polymer-Based Formulations for Fisetin Delivery and Regulatory Effects in Hyperactive Human Microglia

Branched star polymers offer exciting opportunities in enhancing the efficacy of nanocarriers in delivering biologically active lipophilic agents. We demonstrate that the star polymeric architecture can be leveraged to yield soft nanoparticles of vesicular morphology with precisely located stimuli-sensitive chemical entities. Amphiphilic stars of AB₂ (A = PEG, B = PCL) composition with/without oxidative stress or reduction responsive units at the core junction of A and B arms, are constructed using synthetic articulation. Fisetin, a natural flavonoid with remarkable anti-inflammatory and antioxidant properties, but of limited clinical value due to its poor aqueous solubility, was physically encapsulated into miktoarm star-derived aqueous polymersomes. We evaluated polymersomes and fisetin separately, and in combination, in human microglia (HMC3), to show if (i) polymersomes are toxic; (ii) fisetin reduces the abundance of reactive oxygen species (ROS); and (iii) fisetin modulates the activation of ERK1/2. These signaling molecules and pathways are implicated in inflammatory processes and cell survival. Fisetin, both incorporated and non-incorporated into polymersomes, reduced ROS and ERK1/2 phosphorylation in lipopolysaccharide-treated human microglia, normalizing excessive oxidative stress and ERK-mediated signaling. This article is protected by copyright. All rights reserved.

A novel strategy for comprehensive optimization of structural and operational parameters in a supersonic separator using computational fluid dynamics modeling

In this study, the effects of several structural and operational parameters affecting the separation efficiency of supersonic separators were investigated by numerical methods. Different turbulence models were used and their accuracies were evaluated. Based on the error analysis, the V2-f turbulence model was more accurate for describing the high swirling turbulent flow than other investigated turbulence models. Therefore, the V2-f turbulence model and particle tracing model were selected to optimize the structure of the convergence part, the diffuser, the drainage port, and the swirler. The cooling performance of three line-type in the convergent section were calculated. The simulation results demonstrated that the convergent section designed by the Witoszynski curve had higher cooling depth compared to the Bi-cubic and Quintic curves. Furthermore, the expansion angle of 2° resulted in the highest stability of fluid flow and therefore was selected in the design of the diffuser. The effect of incorporating the swirler and its structure on the separation performance of supersonic separator was also studied. Three different swirler types, including axial, wall-mounted, and helical, were investigated. It was observed that installing the swirler significantly improved the separation efficiency of the supersonic separator. In addition, the simulation results demonstrated that the separation efficiency was higher for the axial swirler compared to the wall-mounted and helical swirlers. Therefore, for the improved nozzle, the swirling flow was generated by the axial swirler. The optimized axial swirler was constructed from 12 arced vanes each of which had a swirl angle of 40°. For the optimized structure, the effects of operating parameters such as inlet temperature, pressure recovery ratio, density, and droplet size was also investigated. It was concluded that increasing the droplet size and density significantly improved the separation efficiency of the supersonic separator. For hydrocarbon droplets, the separation efficiency improved from 4.6 to 76.7% upon increasing the droplet size from 0.1 to 2 µm.

A predictive PC-SAFT EOS based on COSMO for pharmaceutical compounds

The present study was conducted to develop a predictive type of PC-SAFT EOS by incorporating the COSMO computations. With the proposed model, the physical adjustable inputs to PC-SAFT EOS were determined from the suggested correlations with dependency to COSMO computation results. Afterwards, we tested the reliability of the proposed predictive PC-SAFT EOS by modeling the solubility data of certain pharmaceutical compounds in pure and mixed solvents and their octanol/water partition coefficients. The obtained RMSE based on logarithmic scale for the predictive PC-SAFT EOS was 1.435 for all of the solubility calculations. The reported values (1.435) had a lower value than RMSE for COSMO-SAC model (4.385), which is the same as that for RMSE for COSMO-RS model (1.412). The standard RMSE for octanol/water partition coefficient of the investigated pharmaceutical compounds was estimated to be 1.515.

Application of PC-SAFT EOS for Pharmaceuticals: Solubility, Co-Crystal, and Thermodynamic Modeling

In this study, the applicability of the perturbed chain statistical associating fluid theory (PC-SAFT) was evaluated for pharmaceutical compounds. For this purpose, the parameters of the PC-SAFT equation of state (EOS) were regressed by applying the experimental solubility data of 54 pharmaceuticals in pure solvents. The reported errors for train and test data show the suitability of the PC-SAFT EOS. The applicability of the PC-SAFT EOS was explored by its prediction accuracy for the ternary system of medicine in solvent mixtures. The model errors were 23 and 26% for two ternary systems of salicylic acid and lidocaine HCl in solvent mixtures of ethanol and water, respectively. The co-crystal formation of salicylic acid-sulfamethazine in methanol was investigated by the PC-SAFT EOS. Finally, the reaction and crystallization sections for acetaminophen production from p-aminophenol were simulated by accompanying the PC-SAFT EOS and equilibrium assumption. The purification efficiencies for acetaminophen were obtained to be 93-98% for different temperatures.

Thermophysical and rheological properties of sorbitol + ([mmim](MeO)2PO2) ionic liquid solutions: Solubility, density and viscosity

In this study, the solubility, density and viscosity of sorbitol as a sugar alcohol in the ([mmim](MeO)₂PO₂) ionic liquid (IL) were measured. The results indicated that sorbitol is highly soluble in this IL. The Flory-Huggins model with an average value for the χ parameter was successfully applied to predict the solubility of sorbitol in IL. The thermodynamic properties such as enthalpy, entropy and Gibbs free energy of dissolution were obtained using experimental solubility data, which demonstrated that the dissolution process is endothermic and non-spontaneous and includes an entropy increase. In addition, the apparent molar volume, apparent molar expansion and thermal expansion coefficient were calculated. The study of the rheological behavior revealed that the sorbitol/IL solution is Newtonian and the Arrhenius, Litovitz, Orrick-Erbar-Type and Vogel-Fulcher-Tamman models were used to correlate the viscosity data.

A Novel Approach in Sorting Chirality Species of Single-Wall Carbon Nanotubes Based on an Aqueous Two-Phase System of Polymer-Salt

Sorting of distinct (n, m) chirality species of single-wall carbon nanotubes (SWCNTs) is essential for progress in technical applications in the field of electronic and optic devices. The purpose of this study is to investigate the isolation of single-wall carbon nanotubes based on diameters/chirality in a polymer-salt (polyethylene glycol and sodium citrate) aqueous two-phase system (ATPS) a substitute for common polymer-polymer (polyethylene glycol and dextran) system. The ATPS based on polymer-salt used instead of the common polymer-polymer system due to low viscosity, reduced surface tension, and lower cost of sodium citrate compared to the dextran. For this purpose, the ratio of concentrations of polyethylene glycol to sodium citrate as well as the effect of temperature on the isolation are both investigated and the selectivity and the recovery estimated approximately. The absorbance spectra from both top and bottom phases at different polymer and salt contents and at different temperatures show that by using this system in optimal conditions of polymer to salt ratio of 2:1 at temperature of 20 °C, a suitable separation of nanotubes with 85% yield of the chiral groups of 9 and 10 can be obtained.

Bioconjugation of enzyme with silica microparticles: a promising platform for α-amylase partitioning

Here, we report the implementation of α-amylase conjugated silica microparticles for improvement of α-amylase partitioning in a PEG–organic salt-based aqueous two phase system. A direct reduction method was employed for the synthesis of silica microparticles with simultaneous introduction of α-amylase. In this context, we synthesized three different silica α-amylase conjugated microparticles with variation of tetraethyl orthosilicate concentration, and thus the effect of final particle size and enzyme loading on partitioning was also studied. The partition coefficient ratio of α-amylase to Si:α-amylase of 2.186 : 21.701 validated an almost tenfold increase in separation. The microscopic structure of the system was thoroughly investigated in order to understand the extraction mechanism and any possible denaturation. Improved partition coefficients can be interpreted by the formation of α-amylase–silica–PEG carriers. Furthermore, circular dichroism (CD) spectra validated partial unfolding of the enzyme.

Here, we report the implementation of α-amylase conjugated silica microparticles for improvement of α-amylase partitioning in a PEG–organic salt-based aqueous two phase system.

Pervaporation separation of ethyl acetate from aqueous solutions using ZSM-5 filled dual-layer poly(ether-block-amide)/polyethersulfone membrane

In the present study, dual-layer mixed matrix membranes (MMMs) were prepared by incorporating ZSM-5 zeolite into poly(ether-block-amide) (PEBA) as an active layer on the polyethersulfone (PES) membrane as a support layer for pervaporation separation of ethyl acetate (EAc) from EAc/water mixtures. The ZSM-5 zeolite nanoparticles were synthesized by the hydrothermal technique and characterized using XRD, XRF and FESEM analysis. The ATR-FTIR, SEM, DSC and contact angle tests were used to characterize the fabricated MMMs. The effect of ZSM-5 concentration on the performance of the membranes was investigated by the pervaporation experiments and the results showed that loading 10% wt% ZSM-5 into the PEBA matrix had the best separation performance. The effect of feed concentration (1–5 wt%) and operating temperature (30–50 °C) on the separation factor and permeation flux of the neat PEBA/PES and PEBA/PES membranes containing 10 wt% ZSM-5 were studied at laminar and turbulent feed flow regimes. Analysis of variance was used to investigate the interaction effect of EAc concentration and temperature on the performance of the prepared membranes. It was observed that both feed concentration and temperature had positive effects on the total permeation flux and separation factor. The ZSM-5/PEBA/PES membrane containing 10 wt% ZSM-5 showed a separation factor and total flux of 124.94 and 1882 g m⁻² h⁻¹ at laminar flow and 134.22 and 1985 g m⁻² h⁻¹ at turbulent flow, respectively for a feed concentration of 5 wt% and temperature of 50 °C.

Dual-layer mixed matrix membranes were prepared by incorporating ZSM-5 zeolite into PEBA as an active layer on the PES membrane as a support layer for pervaporation separation of EAc from the EAc/water mixtures.

Computational fluid dynamic modeling of a pervaporation process for removal of styrene from petrochemical wastewater

In this study, a predictive model was developed to describe the process of separation of volatile organic compounds.

PEGylated silica-enzyme nanoconjugates: a new frontier in large scale separation of α-amylase

High resolution is nearly lost at the expense of throughput in most conventional bioseparation methods. Nanoparticles, due to their high surface to volume ratio, are attractiveenzyme carriers, which can boost the performance of extraction manifold. Here, wereport design and application ofa method highly capable of improving the partitioning of α-amylase in aqueous two-phase system of polymer and salt. Silica nanoparticle introduced to the system acts as a bridge that connects the enzyme and polymer. Theconjugated nanoparticles form the major part of the upper phase and thus significantly enhance the protein recovery. A thorough investigation was performed on the structure of the nanoconjugatesas well as analyzing the conformational structure of the enzyme after conjugationto explore anypossible denaturation.

The role of co-solvents in improving the direct transesterification of wet microalgal biomass under supercritical condition

In this research, direct conversion of wet algal biomass into biodiesel using supercritical methanol was studied. In this process, microalgal lipids simultaneously was extracted and converted to biodiesel under high pressure and temperature conditions without using any catalyst. Several experiments have been performed to optimize the methanol amount and it has been revealed that the best performance was achieved by using methanol/wet biomass ratio of 8:1. The effect of using various co-solvents in increasing the efficiency of the supercritical process was investigated. It has been shown that hexane was the most effective co-solvent and its optimal ratio respect to wet biomass was 6:1. The results indicated that compare to conventional extraction plus transesterification reaction, fatty acid methyl esters (FAMEs) yield was slightly higher in the direct conversion process. Moreover, increasing the moisture content up to 80% has no significant effect on reducing the performance of this process.

Effect of various carbon sources on biomass and lipid production of Chlorella vulgaris during nutrient sufficient and nitrogen starvation conditions

In this research, a two-stage process consisting of cultivation in nutrient rich and nitrogen starvation conditions was employed to enhance lipid production in Chlorella vulgaris algal biomass. The effect of supplying different organic and inorganic carbon sources on cultivation behavior was investigated. During nutrient sufficient condition (stage I), the highest biomass productivity of 0.158±0.011g/L/d was achieved by using sodium bicarbonate followed by 0.130±0.013, 0.111±0.005 and 0.098±0.003g/L/d for sodium acetate, carbon dioxide and molasses, respectively. Cultivation under nitrogen starvation process (stage II) indicated that the lipid and fatty acid content increased continuously to a maximum value at day 2. Using carbon dioxide resulted in highest cell density, while using sodium acetate led to the highest fatty acid content. Molasses was not as effective as other carbon sources, but by taking into account its lower price, it can be considered as a suitable carbon source for algal lipid productivity.

Influence of process variables on extraction of Cefalexin in a novel biocompatible ionic liquid based-aqueous two phase system

Despite the fact that ionic liquid-based aqueous two phase systems (ATPSs) have been widely studied for extraction purposes, the adequacy of biodegradable organic salts as salting out agents has been left unexploited.

Experimental study and thermodynamic modeling for purification of extracted algal lipids using an organic/aqueous two-phase system

Adding water and non-polar organic solvent to the crude extracts will form two-phase system and purify the extracted lipids.