Fabrication and modification of cellulose aerogels from Vietnamese water hyacinth for oil adsorption application

Silane and fluorine free facile hydrophobicization of water hyacinth biomass for oil-water separations

As the adverse effects of using plastics and perfluorinated alkyl substances become more apparent, there is a growing need for sustainable hydrophobic products. Cellulose and its derivatives are the most abundant and widely used polymers, and cellulose-based products have great potential in industries where plastics and other hydrophobic polymers are used, such as stain-resistant fabrics, food packaging, and oil-water separation applications. In this study, we extracted cellulose from water hyacinth (WH) biomass, known for its negative environmental impact, and converted it into hydrophobic cellulose. This addresses the issue of managing WH waste and creating an environmentally friendly hydrophobic material. Initially, aldehyde groups were introduced through oxidation with periodate, followed by direct octadecyl amine (ODA) grafting onto dialdehyde cellulose (DAC) via a Schiff base condensation. The resulting ODA modified cellulose (ODA-C) was dispersed in ethanol and used to coat various materials, including cotton fabric, cellulose filter paper, and packaging paper. The modified materials showed excellent hydrophobicity as measured by their water contact angles (WCAs), and the application of the coating was demonstrated for oil-water separation, stain-resistant hydrophobic fabric, and paper-based packaging materials. FTIR, XRD, and WCA analysis confirmed the successful modification of cellulose. A high separation efficiency of 99% was achieved for diesel/water separation using modified filter paper (MoFP), under gravity. On application of the coating, cotton fabric became hydrophobic and resisted staining from dye, and paper-based packaging materials became more robust by becoming water-resistant. Overall, the facile synthesis, low cost, high efficiency, and use of environmentally friendly sustainable materials make this a promising strategy for hydrophobically modifying surfaces for a wide range of applications while reducing the menace of water hyacinth.

Cellulose cryogels from herbal residues for oily wastewater purification

Recycling herbal residues for oily wastewater purification is a potential way to use the wastes to treat wastes. Cellulose extracted from herbal residues is a fine material for cryogel fabrication. However, the cellulose cryogels were not suitable for oily wastewater treatment due to their amphiphilicity. To address this issue, the cryogels were modified with methyltrimethoxysilane (MTMS), which made them hydrophobic and reduced their surface energy. In this study, the herbal residues (Ficus microcarpa L. f) were used in cryogel preparation for the first time. The cryogels exhibit super lightweight and low density. The modified cryogels show excellent sorption capacity for free oils, especially silicone oil (51.22 g/g), and outperformed some recent sorbents. They also effectively separated water-in-toluene emulsion stabilized by Span 80, with a separation efficiency of 98.57 % and a flux of 1474.67 L/m2h. This study demonstrated a novel application of waste herbal residues in the field of environmental remediation.

Magnetite nanoparticles decorated on cellulose aerogel for p-nitrophenol Fenton degradation: Effects of the active phase loading, cross-linker agent and preparation method

Magnetite nanoparticles (Fe3O4 NPs) are among the most effective Fenton-Like heterogeneous catalysts for degrading environmental contaminants. However, Fe3O4 NPs aggregate easily and have poor dispersion stability because of their magnetic properties, which seriously decrease their catalytic efficiency. In this study, a novel environmentally friendly method for synthesising Fe3O4@CA was proposed. Fe3O4 NPs were immobilized on the 3D cellulose aerogels (CAs) in order to augment the degradation efficiency of p-nitrophenol (PNP) treatment and make the separation of the catalyst accessible by vacuum filtration method. Besides, CAs were fabricated from a cellulose source extracted from water hyacinth by using different cross-linking agents, such as kymene (KM) and polyvinyl alcohol-glutaraldehyde system (PVA-GA), and other drying methods, including vacuum thermal drying and freeze drying, were evaluated in the synthesis process. As-synthesized samples were analysed by various methods, including Powder X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and Brunauer-Emmett-Teller. Then, using ultraviolet-visible spectroscopy, the difference in the degradability of PNP of the obtained material samples was also investigated to determine their potential applications. Results highlighted that the Fe3O4-3@CA-KF catalyst with an Fe3O4 loading of 0.40 g/gCA used KM as a cross-linker and the freeze-drying method demonstrated the highest PNP removal efficiency (92.5 %) in all Fe3O4@CA samples with a H2O2 content of 5 g/L. The degradation kinetics and well-fitted pseudo-first-order model were investigated. Notably, after five successive PNP degradation experiments, this catalyst retained ∼80 % of the ability to degrade PNP, indicating its outstanding reusability. In environmental remediation, this study provides valuable insights into the development of simply separated and high-efficiency catalysts for heterogeneous catalytic reactions.