ABSTRACT
The study involves development of a green biorefinery process for obtaining fucoidan, laminarin, mannitol, alginate and protein from dry and fresh Fucus vesiculosus and Ascophyllum nodosum using hydrochloric acid and a green extraction solvent. After the extraction of fucoidan which was the targeted biomolecule, an extract and by-product (residual biomass) were obtained. The extract was passed through an ultrafiltration membrane, where fucoidan was obtained in the ultrafiltration retentate while ultrafiltration permeate was analysed for laminarin and mannitol. The residual biomass was used for obtaining alginate using ultrasound (20 kHz, 64 % amplitude and 32 min, optimum parameters for alginate extraction based on our previous study). All the samples, showed good results for alginate, laminarin and mannitol, indicating that the by-products can be utilised using this green extraction process. The comparison of both dry and fresh seaweed is relevant from an industry perspective, as fresh seaweed can directly be used for extraction, avoiding drying which adds significantly to the cost of the process. Life cycle impact assessment of the complete seaweed value chain has been carried out to identify the energy demand and key environmental hotspots. This biorefinery process can be used by industry to improve their processes and utilise the by-products generated efficiently.
Subject(s)
Ascophyllum , Fucus , Glucans , Seaweed , Alginates/metabolism , Seaweed/metabolism , Fucus/metabolism , Mannitol , Polysaccharides , ProteinsABSTRACT
Polyvinylidene fluoride (PVDF) polymers are known for their diverse range of industrial applications and are considered important raw materials for membrane manufacturing. In view of circularity and resource efficiency, the present work mainly deals with the reusability of waste polymer 'gels' produced during the manufacturing of PVDF membranes. Herein, solidified PVDF gels were first prepared from polymer solutions as model waste gels, which were then subsequently used to prepare membranes via the phase inversion process. The structural analysis of fabricated membranes confirmed the retention of molecular integrity even after reprocessing, whereas the morphological analysis showed a symmetric bi-continuous porous structure. The filtration performance of membranes fabricated from waste gels was studied in a crossflow assembly. The results demonstrate the feasibility of gel-derived membranes as potential microfiltration membranes exhibiting a pure water flux of 478 LMH with a mean pore size of ~0.2 µm. To further evaluate industrial applicability, the performance of the membranes was tested in the clarification of industrial wastewater, and the membranes showed good recyclability with about 52% flux recovery. The performance of gel-derived membranes thus demonstrates the recycling of waste polymer gels for improving the sustainability of membrane fabrication processes.
ABSTRACT
Controlled depolymerization of cellulose is essential for the production of valuable cellooligosaccharides and cellobiose from lignocellulosic biomass. However, enzymatic cellulose hydrolysis involves multiple synergistically acting enzymes, making difficult to control the depolymerization process and generate desired product. This work exploits the varying adsorption properties of the cellulase components to the cellulosic substrate and aims to control the enzyme activity. Cellulase adsorption was favored on pretreated cellulosic biomass as compared to synthetic cellulose. Preferential adsorption of exocellulases was observed over endocellulase, while ß-glucosidases remained unadsorbed. Adsorbed enzyme fraction with bound exocellulases when used for hydrolysis generated cellobiose predominantly, while the unadsorbed enzymes in the liquid fraction produced cellooligosaccharides majorly, owing to its high endocellulases activity. Thus, the differential adsorption phenomenon of the cellulase components can be used for the controlling cellulose hydrolysis for the production of an array of sugars.
