Biocrude Production via Non-Catalytic Supercritical Hydrothermal Liquefaction of Fucus vesiculosus Seaweed Processing Residues

The potential of using cold water brown macroalgae Fucus vesiculosus for biocrude production via non-catalytic supercritical hydrothermal liquefaction (HTL) was studied. Demineralization, residue neutralization, and high value-added product (alginate and fucoidan) extraction processes were carried out before using the biomass for HTL biocrude production. Acid leaching was carried out using three demineralization agents: distilled water, dilute citric acid solution, and the diluted acidic aqueous by-product from a continuous HTL pilot facility. Alginate was extracted via H2SO4 and NaCO3 bathing, and fucoidan was extracted using CaCl2. Experimental data show that none of the leaching agents was greatly efficient in removing inorganics, with citric acid leaching with extensive neutralization reaching the highest ash removal efficiency of 47%. The produced 6 sets of biocrudes were characterized by elemental and thermogravimetric analyses. Short (10-min retention) HTL and the extent of leaching residue neutralization were also investigated. Highest biocrude yields were recorded when liquefying non-neutralized citric acid leaching, alginate, and fucoidan extraction residues. On the other hand, thermochemical conversions of short retention time HTL, full neutralization extent, and baseline (dried raw macroalgae) biomass performed worse. Specifically, the highest biocrude yield of 28.2 ± 2.5 wt.% on dry ash-free feedstock basis was recorded when liquefying alginate extraction residues. Moreover, the highest energy recovery of 52.8% was recorded when converting fucoidan extraction residues.

Concentration Optimization Na2CO3 Alginates From Turbinaria sp. As Raw Material Electrolite Polymer For DSSC

Polymer electrolyte DSSC is one component of the application can convert solar energy into electrical energy. The polymer electrolyte can be synthesized from brown seaweed Turbinaria sp. However, the optimization of alginate extraction has not been widely carried out, so the aim of this study was to determine the optimum conditions for variations in the concentration of Na2CO3 (3%, 5%, 7%) in extracts from Turbinaria sp as raw material for polymer electrolyte synthesis for DSSC. Alginate optimum extraction results known by percentage yield, moisture content and functional groups using FTIR analysis. The optimum conditions for alginate extraction from Turbinaria sp are Na2CO3 5% and a temperature of 60 oC with a yield of 23.81% and a moisture content of 8.1%. FTIR results also indicate the intensity of the strongest mannuronic seen at 822cm-1 wave numbers.

Application of Alginate Extraction Residue for Al(Iii) Ions Biosorption: A Complete Batch System Evaluation

The residue derived from the alginate extraction from S. filipendula was applied for the biosorption of aluminum from aqueous medium. The adsorptive capacity of the residue (RES) was completely evaluated in batch mode. The effect of pH, contact time, initial concentration and temperature was assessed through kinetic, equilibrium and thermodynamic studies. The biosorbent was characterized prior and post-Al biosorption by N2 physisorption, Hg porosimetry, He picnometry and thermogravimetry analyses. Equilibrium was achieved in 60 minutes. Kinetics obeys pseudo-second order model at aluminum higher concentrations. Isotherms followed Freundlich model at low temperature (293.15 K) and D-R or Langmuir model at higher temperatures (303 and 313 K). Data modeling indicated the occurrence of both chemical and physical interactions in the aluminum adsorption mechanism using RES. The maximum adsorption capacity obtained was of 1.431 mmol/g at 293 K. The biosorption showed a spontaneous, favorable and exotherm character. A simplified batch design was performed, indicating that the residue is a viable biosorbent, achieving high percentages of removal using low biomass dosage.

Trends in seaweed resource use and aquaculture in South Africa and Namibia over the last 30 years

The seaweed industry of temperate Southern Africa was last reviewed in 2003. Since then there have been considerable changes. There are three main uses of kelp (mostly Ecklonia maxima, with some Laminaria pallida) in South Africa. The collection of wash-up for drying and exporting for alginate extraction has drastically reduced to very small amounts in recent years. The boat harvest of fresh kelp for abalone feed in land-based farms has reached a plateau of between 4000 and 5000 t fresh per annum. The diver harvest of E. maxima for agricultural liquid plant growth enhancer shows a constant increase over several years, is still growing, and is currently over 3000 t fresh per annum. The small intertidal collection of Gelidium pristoides as export for agar production has maintained a small, sustainable production of around 100 t dry for many years. Former Gracilaria industries in sheltered bays in both South Africa and Namibia have collapsed, and there is currently no commercial collection. There was commercial raft aquaculture production of Gracilaria in Lüderitz Bay, Namibia for a number of years, but this is no longer practised. Currently, the only commercial seaweed use in Namibia is of L. pallida. Annually, ca. 150 t of fresh wash-up is collected, in Lüderitz, to be used as feed in land-based abalone aquaculture. There are a number of small start-up companies experimenting with seaweed products for cosmetics and nutritional products in both countries, some involving species of Ulva and Porphyra. The former species is a major aquaculture product, with around 2000 t fresh yr–1 being produced in integrated land-based systems with abalone.

Study of microwave hydrothermal production of lactic acid from seaweed-derived alginate using a response surface methodology based on the Box-Behnken design

<p class="Mabstract">A microwave hydrothermal treatment was used for the chemical production of lactic acid from alginate extracted from the brown seaweed <em>Padina Durvillaei</em>, collected in the coastal area of Ecuador. The microwave hydrothermal treatment was studied through a response surface methodology based on the Box-Behnken design, using temperature, reaction time, and catalyst concentration as the manipulated variables and the yield as a response factor. The characterization of alginate was performed by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). The lactic acid produced was quantified using Gas Chromatography - Ion Mobility Spectrometry (GC-IMS). The results show that temperature and catalyst concentration played the most critical roles in alginate extraction and lactic acid production. The optimal experimental conditions for alginate extraction from brown seaweed were: temperature = 92.91°C, time = 110.81 min and catalyst (Na₂CO₃) concentration = 2.60%, with a yield = 29.19%. Although the experimental evidence indicates a positive influence of microwaves' use on the production of lactic acid from alginate through hydrothermal treatment, a new study considering temperatures above 220°C and reaction times below 60 min should be developed.</p>