Improved Performance of CaCl2 Incorporated Polyethersulfone Ultrafiltration Membranes

Poly(ethersulfone) (PES) / poly(vinylpyrrolidone) (PVP) blend membranes modified with calcium chloride (CaCl2) were prepared by phase inversion method. Effect of CaCl2 on the morphology, filtration and performance characteristics of the PES/PVP membranes was studied in detail. Results indicated that CaCl2 blend membranes possessed better porosity and flux than the pristine PES membrane. Dye separation efficiency of CaCl2 blend membranes was also increased considerably. Especially, the PES/PVP blend membrane with 1 wt% CaCl2 showed highest permeate flux and improved dye rejection. Fouling analysis carried out on CaCl2 blend membranes clearly showed that these membranes possessed better antifouling effect than pure PES membrane. Thus the CaCl2 blended PES/PVP membranes are more promising for the treatment of dye polluted wastewater

Liquid biphasic flotation for the purification of C-phycocyanin from Spirulina platensis microalga

Liquid biphasic flotation (LBF), an integrated process of liquid biphasic system (LBS) and adsorptive bubbles flotation, was used for the purification of C-phycocyanin from S. platensis microalgae. Various experimental parameters such as type of phase forming polymer and salt, concentration of phase forming components, system pH, volume ratio, air flotation time and crude extract concentration were evaluated to maximise the C-phycocyanin recovery yield and purity. The optimal conditions for the LBF system achieving C-phycocyanin purification fold of 3.49 compared to 2.43 from the initial LBF conditions was in polyethylene glycol (PEG) 4000 and potassium phosphate combination, with 250 g/L of polymer and salt concentration each, volume ratio of 1:0.85, system pH of 7.0, air flotation duration of 7 min and phycocyanin crude extract concentration of 0.625 %w/w. The LBF has effectively enhanced the purification of C-phycocyanin in a cost effective and simple processing

Insights into adsorption theory of phenol removal using a circulating fluidized bed system

Phenol is one of the most dangerous industrial pollutants in water sources due to its toxic effects on humans and animals. The adsorption process using activated carbon is one of the applicable methods that can be used to remove phenol traces and it is found to be the most efficient due to its various advantages. The present study investigates phenol adsorption using activated carbon which was hand coated onto glass beads. Various calculations were conducted with the data obtained from batch and column adsorption. Kinetic model analysis indicated that the system was best suited for pseudo-second-order kinetics. Thermodynamic parameters such as a change in enthalpy, change in entropy, and change in Gibbs free energy were evaluated, and it can be inferred from the results that this adsorption is endothermic and non-spontaneous for batch study. Physisorption can be inferred from low values of change in enthalpy and change in Gibbs free energy. From the two diffusion models, it was concluded that there is more than one rate-limiting step. The Temkin isotherm model, among the various isotherm models studied, was found to have the best fit with an R2 value of 0.987. The energy value (E) estimated using the Dubinin–Radushkevich isotherm model also proved that the system is physisorption in nature. The column study kinetic calculations indicated that for the column experiment, the process followed was the second-order kinetic model and the thermodynamic report concluded the process to be spontaneous and feasible. MATLAB coding was done for the entire calculations involved in the project, which can be utilized for future applications

Ag-CuO-Decorated Ceramic Membranes for Effective Treatment of Oily Wastewater

Although ultrafiltration is a reliable method for separating oily wastewater, the process is limited by problems of low flux and membrane fouling. In this study, for the first time, commercial TiO2/ZrO2 ceramic membranes modified with silver-functionalized copper oxide (Ag-CuO) nanoparticles are reported for the improved separation performance of emulsified oil. Ag-CuO nanoparticles were synthesized via hydrothermal technique and dip-coated onto commercial membranes at varying concentrations (0.1, 0.5, and 1.0 wt.%). The prepared membranes were further examined to understand the improvements in oil-water separation due to Ag-CuO coating. All modified ceramic membranes exhibited higher hydrophilicity and decreased porosity. Additionally, the permeate flux, oil rejection, and antifouling performance of the Ag-CuO-coated membranes were more significantly improved than the pristine commercial membrane. The 0.5 wt.% modified membrane exhibited a 30% higher water flux (303.63 L m−2 h−1) and better oil rejection efficiency (97.8%) for oil/water separation among the modified membranes. After several separation cycles, the 0.5 wt.% Ag-CuO-modified membranes showed a constant permeate flux with an excellent oil rejection of >95% compared with the unmodified membrane. Moreover, the corrosion resistance of the coated membrane against acid, alkali, actual seawater, and oily wastewater was remarkable. Thus, the Ag-CuO-modified ceramic membranes are promising for oil separation applications due to their high flux, enhanced oil rejection, better antifouling characteristics, and good stability

Microalgae: A potential alternative to health supplementation for humans

Microalgae has been consumed in human diet for thousands of years. It is an under-exploited crop for production of dietary foods. Microalgae cultivation does not compete with land and resources required for traditional crops and has a superior yield compared to terrestrial crops. Its high protein content has exhibited a huge potential to meet the dietary requirements of growing population. Apart from being a source of protein, presence of various bio-active components in microalgae provide an added health benefit. This review describes various microalgal sources of proteins and other bio-active components. One of the heavily studied group of bio-active components are pigments due to their anticarcenogenic, antioxidative and antihypertensive properties. Compared to various plant and floral species, microalgae contain higher amounts of pigments. Microalgal derived proteins have complete Essential Amino Acids (EAA) profiles and their protein content is higher than conventional sources such as meat, poultry and dairy products. However, microalgal based functional foods have not flooded the market. The lack of awareness coupled with scarce incentives for producers result in under-exploitation of microalgal potential. Application of microalgal derived components as dietary and nutraceutical supplements is discussed comprehensively. Keywords: Health, Human, Microalgae, Protein, Supplemen

Waste to bioenergy: a review on the recent conversion technologies

Scientific studies have demonstrated that it is possible to generate a wide variety of bioenergy from biomass residues and waste, and however its cost is not competitive with petro-fuels and other renewable energy. On-going efforts are continued extensively to improve conversion technologies in order to reduce production costs. The present review focuses on the conversion technologies for transforming biomass residues and waste to biofuels, specifically their technological concepts, options and prospects for implementation are addressed. The emerging developments in the two primary conversion pathways, namely the thermochemical (i.e. gasification, liquefaction, and pyrolysis) and biochemical (i.e. anaerobic digestion, alcoholic fermentation and photobiological hydrogen production) conversion techniques, are evaluated. Additionally, transesterification, which appears to be the simplest and most economical route to produce biodiesel in large quantity, is discussed. Lastly, the strategies for direct conversion of biomass residues and waste to bioelectricity including the use of combustion and microbial fuel cells are reviewed

Chitosan Coatings Modified with Nanostructured ZnO for the Preservation of Strawberries

Strawberries are highly consumed around the world; however, the post-harvest shelf life is a market challenge to mitigate. It is necessary to guarantee the taste, color, and nutritional value of the fruit for a prolonged period of time. In this work, a nanocoating based on chitosan and ZnO nanoparticles for the preservation of strawberries was developed and examined. The chitosan was obtained from residual shrimp skeletons using the chemical method, and the ZnO nanoparticles were synthesized by the close-spaced sublimation method. X-ray diffraction, scanning electron microscopy, electron dispersion analysis, transmission electron microscopy, and infrared spectroscopy were used to characterize the hybrid coating. The spaghetti-like ZnO nanoparticles presented the typical wurtzite structure, which was uniformly distributed into the chitosan matrix, as observed by the elemental mapping. Measurements of color, texture, pH, titratable acidity, humidity content, and microbiological tests were performed for the strawberries coated with the Chitosan/ZnO hybrid coating, which was uniformly impregnated on the strawberries’ surface. After eight days of storage, the fruit maintained a fresh appearance. The microbial load was reduced because of the synergistic effect between chitosan and ZnO nanoparticles. Global results confirm that coated strawberries are suitable for human consumption