Facile asymmetric modification of graphene nanosheets using κ-carrageenan as a green template.

The synthesis of Janus nanosheets using κ-carrageenan (κ-Ca) as a green template endows a greener and more straightforward method compared to traditional approaches of using wax template. We hypothesize that the hydrogen bonding interaction between κ-Ca and graphene oxide (GO) allows partial masking of GO's single facet, paving the way for the asymmetric modification of the exposed surface. GO is first encapsulated within the porous hydrogel matrix formed by κ-Ca to isolate one of the facets. The exposed surface was then selectively hydrophobized to produce an amphiphilic asymmetrically modified graphene oxide (AMGO). The properties of AMGO synthesized under different κ-Ca/GO ratios were studied. The κ-Ca/GO interactions and the properties of GO and AMGO were investigated and characterized. AMGO was successfully produced with a yield of 90.37 % under optimized synthesis conditions. The separation of κ-Ca and AMGO was conducted without organic solvents, and the κ-Ca could be subsequently recovered. Furthermore, the porous hydrogel matrix formed by κ-Ca and GO exhibited excellent shape-retaining properties with high thermal tolerance of up to 50 °C. Given these benefits, this newly developed method endows sustainability and open the possibility of formulating more flexible material synthesis protocols.

Third-generation L-Lactic acid production by the microwave-assisted hydrolysis of red macroalgae Eucheuma denticulatum extract.

The development of an efficient third-generation L-lactic acid (L-LA) production process from Eucheuma denticulatum extract (EDE) was achieved in this study. Microwave-assisted dilute acid hydrolysis (MADAH) and microwave-assisted hydrothermal hydrolysis (MAHTH) were chosen as the hydrolysis of EDE for the objective of increasing galactose yield. Single-factor optimization of hydrolysis of the EDE was studied, MADAH had high performance in galactose production relative to MAHTH, in which the yield and optimal conditions for both processes were 50.7% (0.1 M H2SO4, 120 °C for 25 min) and 47.8% (0 M H2SO4,160 °C for 35 min), respectively. For fermentation, the optimal L-LA yield was achieved at the inoculum cell density of 4% (w/w) Bacillus coagulans ATCC 7050 with 89.4% and 6% (w/w) Lactobacillus acidophilus LA-14 with 87.6%. In addition, lipid-extracted Chlorella vulgaris residues (CVRs) as co-nutrient supplementation increased the relative abundance of B. coagulans ATCC 7050, thus benefiting L-LA production.

Macroalgae-derived regenerated cellulose in the stabilization of oil-in-water Pickering emulsions.

This study aims to derive regenerated cellulose (RC) from lignin/hemicellulose-free Eucheuma cottonii for its independent stabilization of Pickering emulsion. The RC exhibits a fibrillar morphology with diameters ranging from 17 to 157 nm and stabilizes paraffin oil-Pickering emulsions without any co-stabilizer. It was found that the emulsion stability, viscosities and viscoelasticity correlate positively with RC concentration. All emulsion samples depict gel-like behavior. Under different oil fraction at a constant RC concentration, anomalies were found in emulsion properties. This can be attributed to the aggregating behavior of RC at the oil-water interface, the degree of gel-like structure formation due to materials interaction within the emulsion system, and the variations of microscopic droplet cluster interactions under shear condition. The emulsions portrayed excellent robustness against harsh salinity, high temperature and extreme pH fluctuation. Hence, these findings had elucidated the plausibility of macroalgae-derived RC in enhanced oil recovery application.