Green and efficient extraction of polysaccharides from brown seaweed by adding deep eutectic solvent in subcritical water hydrolysis

Optimization of alginate alkaline extraction technology from Sargassum latifolium and its potential antioxidant and emulsifying properties.

A green approach for alginate extraction from Sargassum muticum brown seaweed using ultrasound-assisted technique

Nitrate contamination of groundwater is a global issue that has stimulated significant research interest. Understanding the prevailing processes of nitrate removal from groundwater, influences of process conditions and the performance of various approaches are vital for successfully dealing with nitrate remediation. Natural and engineered processes of nitrate removal from groundwater are discussed with focus on the performance of natural and engineered innovative techniques for nitrate removal from groundwater. Nitrate removal from groundwater can be accomplished through microbial autotrophic and heterotrophic mechanisms in the subsurface under natural and engineered conditions. The application of these processes to in-situ and ex-situ nitrate removal is also discussed in this review. Further, the effect of temperature, pH, electron donor and biogeochemistry on groundwater nitrate removal are elaborated. While natural attenuation processes result in small amounts of nitrate removal from groundwater, engineered processes are able to achieve significantly higher nitrate removal from groundwater. However, the challenges of secondary pollution need to be addressed in adopting these technologies for groundwater treatment

Nitrate removal from groundwater: a review of natural and engineered processes

Alginate extraction from Sargassum seaweed in the Caribbean region: Optimization using response surface methodology.

SUMMARY
The Japanese brown seaweed Sargassum muticum, recently invaded several shorelines worldwide including the Atlantic coast of Morocco with large well-established populations. Within the framework of a sustainable strategy to control this invasive seaweed, we report on extraction yield, spectroscopic characterization and rheological properties of alginate, a commercially valuable colloid, from harvested biomass of S. muticum. Extraction yield was about 25.6% on dry weight basis. Infrared spectroscopy analysis shows that the obtained Fourier transform infrared spectra of the extracted biopolymer exhibit strong similarities with that of the commercial alginate. Furthermore, Proton nuclear magnetic resonance spectroscopy revealed that S. muticum alginate has almost equal amounts of β-D-mannuronic acid (M; 49%) and α-L-guluronic acid (G; 51%) with an M/G ratio of 1.04 and a high content of heteropolymeric MG GM diads suggesting a sequence distribution of an alternated polymer type. Rheological measurements were performed at different sodium alginate concentrations, temperatures and shear rates. The hydrocolloid exhibited pseudoplastic behavior and showed shear thinning, particularly at high solution concentration and low temperature which is consistent with the rheological behavior reported for commercial alginates. Considering the abundance of S. muticum in the Northwestern Atlantic coast of Morocco and the quality of the extracted hydrogel, this invasive species could be considered as a potential source of alginates.

The invasive brown seaweed Sargassum muticum as new resource for alginate in Morocco: Spectroscopic and rheological characterization

Impedance spectroscopy as a tool to monitor the adsorption and removal of nitrate ions from aqueous solution using zinc aluminum chloride anionic clay.

Complex electrical conductivity as a new technique to monitor the coagulation-flocculation processes in the wastewater treatment of the textile Industry

Various species of polysaccharides were extracted from algae collected from the west coast of Morocco. This area is known for its abundance of various species of algae. The polysaccharides of three species, Sargassum muticum, Cystoseira myriophylloides and Cystoseira baccata were selected and their rheological properties were evaluated at different concentrations (1, 3, 5, 7 and 9% by w/v) and in the temperature range from 10 to 60 °C. FTIR analysis of these polysaccharides was also carried out to identify the functional groups and its analysis revealed the presence of uronic acid groups. These polysaccharides showed non-Newtonian behavior. The evolution of the apparent viscosity as a function of shear rate was described by the power-law model. The values of the flow behavior index were less than unity at high concentration. The consistency coefficient greatly increased. The non-linearity was increased with concentration and it was characterized by a power law, basically for Cystoseira myriophylloides and Cystoseira baccata. Besides, the flow behavior temperature dependence was characterized by the Arrhenius model to extract the activation energy. The values of the activation energy were found between 11.28–13.76 kJ/mol, 15.29–17.67 kJ/mol, and16.83–17.98 kJ/mol for Sargassum muticum, Cystoseira baccata and Cystoseira myriophylloides, respectively.

Extraction of polysaccharides from brown algae: rheological studies

The analysis of the complex permittivity, electrical complex modulus and the hopping conductivity have been employed in order to investigate the impacts of calcium oxide during sludge treatment in textile such as coagulation process. In this context, impedance measurement was performed on five samples, including raw sludge and four compositions containing different amounts of calcium oxide: 2%, 3%, 4% and 5% (w/w). The dielectric spectra of each composition were described by the summation of a power law and a Cole-Cole relaxation model. The relaxation time and the magnitude of the dielectric relaxation obtained from the analysis of dielectric properties showed an increase up to 3% of these parameters with the addition of calcium oxide. Above this critical value, both parameters showed a very small change, suggesting that the aggregation became more stable. In addition, the evolution of the hopping conductivity reached a minimum value at this critical amount (3%). This evolution was well described ...

https://www.tandfonline.com/doi/pdf/10.1080/09593330.2017.1378927

A. Mortadi

Papers

The invasive brown seaweed Sargassum muticum as new resource for alginate in Morocco: Spectroscopic and rheological characterization

Impedance spectroscopy as a tool to monitor the adsorption and removal of nitrate ions from aqueous solution using zinc aluminum chloride anionic clay.

Complex electrical conductivity as a new technique to monitor the coagulation-flocculation processes in the wastewater treatment of the textile Industry

Extraction of polysaccharides from brown algae: rheological studies

Dielectric and electric properties as a tool to investigate the coagulation mechanism during sludge treatment