Miquel F. Llop

Effective and simple methodology to produce nanocellulose-based aerogels for selective oil removal

Spilled oil in seas has a direct impact on the environment and biodiversity. Moreover, there is no clear relationship between the amount of oil in the aquatic environment and its impact, since it mainly depends on the time and season that the oil is spilled. Nowadays, there are several techniques to clean up and recover oil from the sea, including the use of microorganisms, chemicals, controlled burning, dispersants and solidifiers, among others. Sometimes, unfortunately, the best option is to watch and wait for natural attenuation. Cellulose nanofibers have potential environmental applications due to their availability, light weight, mechanical and optical properties, and renewability. Several studies have dealt with modification of their hydrophilic character through silanation and acetylation. Both treatments, despite having a significant impact on the environment, are not plausible on a large scale because of the cost of chemicals and complexity of the modification. In this sense, the present work aims to develop hydrophobic nanocellulose-based aerogels from bleached kraft eucalyptus fibers modified with alkyl ketene dimers. For this, an experimental batch of 24 aerogels was prepared, including three types of CNF (TEMPO-oxidized, enzymatically hydrolyzed and mechanical) and eight modification degrees. The obtained aerogels were characterized in terms of morphology, hydrophilicity and water–oil absorption capacity under static and dynamic conditions, as well as their suitability for recycling and reuse for selective oil removal. The results showed that it is possible to obtain 3D-structured aerogels with a high oil absorption capacity by a simple and presumably low-cost methodology.

Chemical treatment for improving wettability of biofibres into thermoplastic matrices

The use of biofibres as reinforcing agents for composite materials is one of the most promising areas of composite development, but the handicap of their hydrophilic nature has to be resolved to ensure stable composites. This article concerns the effectiveness of chemical modification using fatty acid derivates followed by graft copolymerisation with vinyl monomers to confer hydrophobicity and resistance to enzymatic degradation to biofibres. Oleoyl chloride was used as a fatty acid derivative to modify jute fibres leaving one double bond available for further co-polymerisation with styrene. The chemical modification was applied in swelling and non-swelling solvents and different extents of modification were obtained. The reaction was monitored by FTIR spectroscopy and the extent of modification was calculated from elemental analysis. The copolymerisation reaction was carried out from 2–3 molar% modified jute fibres resulting in highly hydrophobic jute fibres with large resistance to microorganisms. The copolymerisation reaction was also followed by FTIR spectroscopy and covering styrene ratios were deduced from elemental analysis. Additional investigations such as SEM, optical microscopy, enzymatic degradation and floatation techniques were used to support the efficacy of the proposed method.

Recycling dyed cotton textile byproduct fibers as polypropylene reinforcement

The textile industry generates a large amount of byproducts that must be treated before being recycled or disposed of. The treatments to extract the dyeing agents are mandatory, and involve costs and interaction with toxic reagents. A relevant amount of such byproducts are short cotton dyed fibers. Cotton fibers are high-quality cellulosic fibers and can be used as composite reinforcement. In this paper, dyed cotton fibers were used to formulate, obtain and tensile test composite materials. The impact of the presence of dyes was studied and such dyes enhanced the interphase between the matrix and the reinforcement. On the other hand, when a coupling agent was incorporated to the formulation of the composites, the dyes hindered the chemical interactions between the maleic acid and the OH groups of the cellulosic fibers. Nonetheless, the composite materials showed competitive mechanical properties that were better than other natural fiber-reinforced composites and comparable to some glass fiber-based ones. Dyed cotton fibers can be used as reinforcement without further treatment, increasing the value chain of the textile industry and decreasing the chemical treatments necessary to recycle or dispose of dyed textile fibers.