Javier Pinto

Effect of the porous structure of polymer foams on the remediation of oil spills

Current approaches for the remediation of oil spills propose the utilization of functionalized polymeric foams as efficient oil absorbents. However, for the majority of the materials employed, the studies are focused on sophisticated surface treatments while the significant role of the morphological parameters of the porous structure of the pristine foams remains unexplored. Herein, we prove that the structural parameters of the pores of the polymeric foams play a fundamental role for the efficient removal of oil from water. The presented experimental and theoretical study shows that pristine polyurethane foams with highly interconnected open porous structures, and pore sizes below 500 μm are able to reach oil absorption capacities as high as 30 gr of oil per gr of polyurethane. Chemical functionalization of the porous structure does not increase further the oil absorption efficiency but it significantly contributes to the increase of the selectivity of the process. The current findings demonstrate the importance of the right choice of the pristine foams for the fabrication of cost-effective absorbents with high water-oil separation performance.

Oil removal from water–oil emulsions using magnetic nanocomposite fibrous mats

Herein we present the fabrication of hydrophobic and oleophilic poly(methyl methacrylate)-based nanocomposite fibrous mats with magnetic properties, and their utilization for oil removal from stable water–oil emulsions. The incorporation of ferromagnetic iron nanoparticles into the polymeric fibers increases the selectivity and oil removal performance of the fibers, as well as introduces magnetic actuation properties to the material. In all the water–oil emulsions used in this work ranging from 5 to 30 v%, the functional mats can obtain oil absorption efficiencies up to 90%. The oil removal efficiency can reach nearly 100% with just two successive absorption cycles. The high performance achieved makes the presented material a promising candidate for efficient water–oil emulsions separation.

Surface modification of polymeric foams for oil spills remediation

In the last decade, a continuous increasing research activity is focused on the surface functionalization of polymeric porous materials for the efficient removal of oil contaminants from water. This work reviews the most significant recent studies on the functionalization of polyurethane and melamine foams, materials commonly reported for oil-water separation applications. After the identification of the key features of the foams required to optimize their oil removal performance, a wide variety of physicochemical treatments are described together with their effect on the oil absorption selectivity and oil absorption capacity, both critical parameters for the application of the foams in the remediation of oil spills. The efficiencies of the different functionalization processes on the same type of foams are compared, determining the main advantages and potentialities of each treatment and remediation procedure.

Reusable nanocomposite-coated polyurethane foams for the remediation of oil spills

Cost-effective oil absorbents for the remediation of oil spills have been developed following a facile process involving the modification of polyurethane foam surfaces with mixtures of silicon oxide nanoparticles and polydimethylsiloxane. Polyurethane foams with different pore sizes and connectivity are tested, and it was found that the proposed treatment, applied by dip coating and spray coating, strongly improves the intrinsic foams’ performance in terms of selectivity and oil absorption capacity. The modified foams reach oil absorption capacities up to 60xa0g/g and simultaneous negligible water uptake. The treatment is stable after multiple absorption cycles, and therefore, the foams can be reused without significant decrease in their performance, being possible, after five cycles of absorption and recovery of oil, to reach overall oil absorption capacities up to 250xa0g/g.

Enhanced oil removal from water in oil stable emulsions using electrospun nanocomposite fiber mats

Fibrous mats with hydrophobic and oleophilic properties have been fabricated and used as absorbents of oil from stable water in oil emulsions. The mats were prepared by initially mixing two polymers, poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL), in a common solvent. The subsequent electrospinning of the prepared solutions resulted in the production of mechanically stable fiber mats, with enhanced oil absorption capacity and oil absorption selectivity from the emulsions, compared to the pure PMMA or PCL mats. Furthermore, the formed fibrous substrates have been successful in the absorption of oil from different emulsions with a wide range of oil content, from 10 to 80 v%. The performance of the fibrous mats was optimized by the incorporation of hydrophobic silica nanoparticles, reaching oil absorption capacities of 28 g g−1 and negligible water uptake, in the emulsions with 80 v% oil content.

Antibacterial Melamine Foams Decorated with in Situ Synthesized Silver Nanoparticles

A new and straightforward single-step route to decorate melamine foams with silver nanoparticles (ME/Ag) is proposed. Uniform coatings of silver nanoparticles with diameters less than 10 nm are formed in situ directly on the struts surface of the foams, after their dipping in an AgNO3 solution. We prove that the nanoparticles are stably adhered on the foams, and that their amount can be directly controlled by the concentration of the AgNO3 solution and the dipping time. Following this production route, ME/Ag foams can be obtained with silver content ranging between 0.2 and 18.6 wt % and excellent antibacterial performance, making them appropriate for various applications. Herein we explore the possibility to use them as antibacterial filters for water treatment, proving that they are able to remove completely Escherichia coli bacteria from water when filtered at flow rates up to 100 mL/h·cm2 due to the release of less than 1 ppm of Ag+ ions by the foams. No bacterial regrowth was observed after further dilution of the treated water, to arrive below the safety threshold of Ag+ for drinking water (0.1 ppm), demonstrating the excellent bactericide performance of the ME/Ag filters.