Bio-processing of algal bio-refinery: a review on current advances and future perspectives

Microalgae biomass contains various useful bio-active components. Microalgae derived biodiesel has been researched for almost two decades. However, sole biodiesel extraction from microalgae is time-consuming and is not economically feasible due to competitive fossil fuel prices. Microalgae also contains proteins and carbohydrates in abundance. Microalgae are likewise utilized to extract high-value products such as pigments, anti-oxidants and long-chain polyunsaturated fatty acids which are useful in cosmetic, pharmaceutical and nutraceutical industry. These compounds can be extracted simultaneously or sequentially after biodiesel extraction to reduce the total expenditure involved in the process. This approach of bio-refinery is necessary to promote microalgae in the commercial market. Researchers have been keen on utilizing the bio-refinery approach to exploit the valuable components encased by microalgae. Apart from all the beneficial components housed by microalgae, they also help in reducing the anthropogenic CO2 levels of the atmosphere while utilizing saline or wastewater. These benefits enable microalgae as a potential source for bio-refinery approach. Although life-cycle analysis and economic assessment do not favor the use of microalgae biomass feedstock to produce biofuel and co-products with the existing techniques, this review still aims to highlight the beneficial components of microalgae and their importance to humans. In addition, this article also focuses on current and future aspects of improving the feasibility of bio-processing for microalgae bio-refinery

Chitosan/PEO nanofibers electrospun on metallized track-etched membranes: fabrication and characterization

The development of next-generation adsorption, separation, and filtration materials is growing with an increased research focus on polymer composites. In this study, a novel blend of chitosan (CS) and polyethylene oxide (PEO) nanofiber mats was electrospun on titanium (Ti)-coated polyethylene terephthalate (PET) track-etched membranes (TMs) with after-treatment by glutaraldehyde in the vapor phase for enhancing the nanofiber stability by crosslinking. The prepared composite, titanium-coated track-etched nanofiber membrane (TTM-CPnf) was characterized by Fourier transform infra-red (FTIR), water contact angle, and scanning electron microscopy (SEM) analyses. Smooth and uniform CS nanofibers with an average fiber diameter of 156.55 nm were produced from a 70/30 CS/PEO blend solution prepared from 92 wt. % acetic acid and electrospun at 15 cm needle to collector distance with 0.5 mL/h flow rate and an applied voltage of 30 kV on the TTM-CPnf. Short (15 min) and long (72 h)-term solubility tests showed that after 3 h, crosslinked nanofibers were stable in acidic (pH = 3), basic (pH = 13), and neutral (pH = 7) solutions. The crosslinked TTM-CPnf material was biocompatible based on the low mortality of freshwater crustaceans Daphnia magna. The composite membranes comprised of electrospun nanofiber and TMs proved to be biocompatible and may thus be suitable for diverse applications such as dual adsorption–filtration systems in water treatment

Biosynthesis of silver nanoparticle and its application in cell wall disruption to release carbohydrate and lipid from C. vulgaris for biofuel production

Microalgae are the fledging feedstocks yielding raw materials for the production of third generation biofuel. Assorted and conventional cell wall disruption techniques were helpful in extracting lipids and carbohydrates, nevertheless the disadvantages have led the biotechnologists to explore new process to lyse cell wall in a faster and an economical manner. Silver nanoparticles have the ability to break the cell wall of microalgae and release biomolecules effectively. Green synthesis of silver nanoparticles was performed using a novel bacterial isolate of Bacillus subtilis. Characterisation of nanosilver and its effect on cell wall lysis of microalgae were extensively analysed. Cell wall damage was confirmed by lactate dehydrogenase assay and visually by SEM analysis. This first piece of research work on direct use of nanoparticles for cell wall lysis would potentially be advantageous over its conventional approaches and a greener, cost effective and non laborious method for the production of biodiesel

AMORPHOUS EVENT PREVENTION IN WIRELESS SENSOR NETWORK

In many applications wireless sensor can be used to detect the events in those applications. With the advances in sensing, communication, and computation, there is an increasing need to track mobile events such as air pollutant diffusion, toxic gas leakage, or wildfire spreading using mobile sensors such as robots. Lots of existing work use control theory to plan the path of mobile sensors by assuming that the event evolution is known in advance. This assumption has severely limited the applicability of existing approaches. In this paper we aim to design a detecting, tracking and preventing approach that is capable of identifying multiple events with dynamic event signatures and providing event evolution history that may include event merge, split, create and destroy. We also focused on the power consumption

Statistical optimization of harvesting Chlorella vulgaris using a novel bio-source, Strychnos potatorum

The present study was aimed at harvesting microalga, Chlorella vulgaris, by bioflocculation using seed powder of clearing nut, Strychnos potatorum. The research was essentially the prime step to yield a large biomass for utilising the cells in biodiesel production. Optimization of the parameters influencing bioflocculation was carried out statistically using RSM. The optimized conditions were 100 mg L−1 bioflocculant concentration, 35 °C temperature, 150 rpm agitation speed and 30 min incubation time and resulted in a maximum efficiency of 99.68%. Through cell viability test, using Trypan blue stain, it was found that cells were completely intact when treated with bioflocculant, but destroyed when exposed to chemical flocculant, alum. The overall study represented that S. potatorum could potentially be a bioflocculant of microalgal cells and a promising substitute for expensive and hazardous chemical flocculants. Moreover, this bioflocculant demonstrated their utility to harvest microalgal cells by economically, effectively and in an ecofriendly way

Protective effect of eugenol from Mesua ferrea on the oxidative damages caused by 5-fluorouracil in PBMC cells

5-Fluorouracil (5-FU), a pyrimidine analogue with fluorine at C5 position, is one of the chemotherapy drugs used to treat various cancers. Though 5-FU is a very promising anticancer drug, it can cause side effects such as coronary thrombosis, intestinal mucositis, cognitive impairment, and anaemia through the generation of free radicals, damages the normal cells and also leads to apoptosis. To overcome such toxic effects of 5-FU, in the present work we have explored the cytoprotective potential of eugenol, the antioxidant active compound available in ethanolic extract of an Indian herbal drug Mesua ferrea. Aim of the present study was to evaluate the cytoprotective effect of eugenol against 5-FU toxicity in peripheral blood mononuclear cells (PBMC). Based on MTT assay, it is noticed that eugenol significantly prevents the toxicity of 5-FU (73%) in PBMC cells. Eugenol has lowered the generation of intra-cellular ROS (20035.5 AU) when compared to 5-FU treated cells (58918.5 AU). Eugenol exhibited remarkable inhibition of lipid peroxidation (43%) and cell membrane damage (LDH release: 488.02 IU/L). Thus, eugenol prevents apoptosis-induced cell death when compared with 5-FU in PBMC cells and hence it can be used to overcome the cytotoxicity caused by 5-FU and it warrants further study

Green synthesis of CdS Quantum dots for photocatalytic and anti-corrosive applications in aqueous media

Inorganic pollutants are the leading cause of water pollution, which harms human health and the environment. The most highly efficient nanoparticles with enhanced photocatalytic activity are semiconductor quantum dots (QDs). The heterogeneous photocatalysis using UV radiation on quantum dots is a fascinating technique for treating polluted sewage with a naturally available plant-based product. In this study, CdS QDs were synthesized using a facile green synthetic protocol in the presence of Coccinia grandis (CG) and Punica granatum (PG) fruit sap as capping and stabilizing agents. XRD, HR-TEM, FT-IR, UV-DRS, and photoluminescence spectroscopy were used to analyze the synthesized CdS QDs. The photocatalytic degradation activity of CdS quantum dots was performed against anionic and cationic dyes under UV light irradiation. The results revealed that PG-capped CdS QDs have the best photocatalytic activity compared to CG-capped CdS QDs.Further, the pseudo-first-order model is used to analyze the kinetics studies. Moreover, the electrochemical measurements of pure zinc and CdS QDs coated Zn (Zn/CdS QDs) plate were tested in three electrolytes: sodium chloride, potassium hydroxide, and hydrochloric acid, which demonstrated the corrosion inhibition ability of prepared CdS QDs. The electrochemical impedance spectra, Tafel plot, and in-situ SPM analysis depict the improving corrosion resistance of the Zn metal plate due to the prepared CdS QDs coatings. Based on the results, the prepared CdS QDs by the green method can be a potential candidate in the water purification and corrosion resistance field