Development of a phosphorous-based biorefinery process for producing lignocellulosic functional materials from coconut wastes.

This work aimed to develop a phosphorous-based biorefinery process for obtaining phosphorylated lignocellulosic fractions in a one-pot protocol from coconut fiber. Natural coconut fiber (NCF) was mixed with 85 % m/m H3PO4 at 70 °C for 1 h to yield the modified coconut fiber (MCF), aqueous phase (AP), and coconut fiber lignin (CFL). MCF was characterized by its TAPPI, FTIR, SEM, EDX, TGA, WCA, and P content. AP was characterized regarding its pH, conductivity, glucose, furfural, HMF, total sugars and ASL contents. CFL structure was evaluated by FTIR, 1H, 31P and 1H-13C HSQC NMR, TGA and P content and was compared to that of milled wood lignin (MWL). It was observed that MCF and CFL were phosphorylated during the pulping (0.54 and 0.23 % wt., respectively), while AP has shown high sugar levels, low inhibitor content, and some remaining phosphorous. The phosphorylation of MCF and CFL also showed an enhancement of their thermal and thermo-oxidative properties. The results show that a platform of functional materials such as biosorbents, biofuels, flame retardants, and biocomposites can be created through an eco-friendly, simple, fast, and novel biorefinery process.

Development of an eco-friendly acetosolv protocol for tuning the acetylation of coconut shell lignin: Structural, antioxidant, solubility and UV-blocking properties.

The optimization of the parameters involved in lignin extraction is crucial for obtaining a lignin with specific structural features for its further valorization. The aim of this work was to develop an eco-friendly organosolv protocol for tuning the acetylation degree of coconut shell lignins (CSLs) by using MgCl2 and HCl as catalyst and co-catalyst, respectively. CSLs were obtained by mixing coconut shell powder with 90% v/v acetic acid combined to no catalyst, 2% v/v HCl and 2% w/v MgCl2 (1, 2 and 3 h) and 2% w/v MgCl2 combined to 0.1, 0.25 and 0.5% v/v HCl (2 h) at 110 °C. CSLs were characterized by FTIR, 1H NMR, GPC and TGA. The effects of the acetylation degree were evaluated on their antioxidant activity (DPPH assay) and UV-blocking capacity in sunscreen formulations. The results have shown that the use of HCl as co-catalyst increased the lignin yield (from 21.4 to 48.8%) and the acetylation degree (from 0.81 to 1.58 mmol g-1), which positively affected thermal (200 < Tonset < 226 °C), antioxidant (46.6 < IC50 < 67.5 µg mL-1) and UV-blocking capacities of CSLs. It can be concluded that the design of the organosolv process was capable of generating lignins with peculiar functionalities and properties through an eco-friendly protocol.