Superhydrophobic polyurethane sponges modified by sepiolite for efficient oil-water separation

A Fluorine-Free Superhydrophobic Cotton Fabric Prepared by a Green and Energy-Saving Method Is Used for Long-Lasting and Efficient Oil-Water Separation

Oil pollution poses a major threat to the ecosystem. Therefore, it is necessary to develop a material that can separate oil and water efficiently. Fabrics have a wide range of applications due to their economic simplicity and degradability. However, the existing methods of preparing superhydrophobic fabrics are complicated and energy-consuming, which are difficult to meet the concept of green and sustainable development. Moreover, various modified fabrics are less stable in harsh environments and do not have the ability to efficiently separate oil and water over a long period of time. In this paper, superhydrophobic zirconium dioxide (ZrO2) obtained from the modification of stearic acid was loaded onto the fabric surface using the adhesive properties of PDMS, resulting in the preparation of superhydrophobic/superoleophilic STA-ZrO2 fabrics. The fabric is made without involving time-consuming and energy-consuming heating, and it offers efficient oil-water separation, good stability and excellent recyclability. Truly in line with the concept of sustainable development.

Magnetic superhydrophobic melamine sponges for crude oil removal from water

This paper proposes the preparation of a new sorbent material based on melamine sponges (MS) with superhydrophobic, superoleophilic, and magnetic properties. This study involved impregnating the surface of commercially available MS with eco-friendly deep eutectic solvents (DES) and Fe3O4 nanoparticles. The DES selection was based on the screening of 105 eutectic mixtures using COSMO-RS modeling. Other parameters affecting the efficiency and selectivity of oil removal from water were optimized using the Box-Bhenken model. Menthol:Thymol (1:1)@Fe3O4-MS exhibited the highest sorption capacity for real crude oils (101.7-127.3 g/g). This new sponge demonstrated paramagnetic behavior (31.06 emu/g), superhydrophobicity (151°), superoleophobicity (0°), low density (15.6 mg/cm3), high porosity (99 %), and excellent mechanical stability. Furthermore, it allows multiple regeneration processes without losing its sorption capacity. Based on these benefits, Menthol:Thymol (1:1)@Fe3O4-MS shows promise as an efficient, cost-effective, and eco-friendly substitute for the existing sorbents.

A novel absorbent, HOF-3@PU: Preparation and application for sustainable and efficient purification of catalpol and ajugol from Rehmannia glutinosa leaves

This study introduced the preparation of a novel HOF-loaded PU sponge (HOF-3@PU) composite for the sustainable and efficient purification of catalpol and ajugol from Rehmannia glutinosa leaves for the first time. HOF-3 was selected as the best adsorbent from the five synthesised HOFs. HOF-3@PU was prepared by ultrasonication, and the loading conditions were optimised. The results showed that the optimum adsorption conditions are as follows: adsorption liquid volume: 160 mL, flow rate: 3.0 mL/min, pH: 6.0, concentration: 1.62 mg/mL for catalpol and 2.18 mg/mL for ajugol. The optimum desorption conditions are as follows: desorption agent: ethanol, volume fraction: 60%, flow rate: 2.0 mL/min, volume: 300 mL and pH: 6.0. Under the optimal process conditions, the adsorption capacities of catalpol and ajugol were 75.62 and 68.41 mg/g, the desorption rates were 78.5 and 86.4% and the purities were 38.7 and 36.5%, respectively.

Photothermal, Magnetic, and Superhydrophobic PU Sponge Decorated with a Fe3O4/MXene/Lignin Composite for Efficient Oil/Water Separation

Frequent oil spills and the discharge of industrial oily wastewaters have become a serious threat to the environment, ecosystem, and human beings. Herein, a photothermal, magnetic, and superhydrophobic PU sponge decorated with a Fe3O4/MXene/lignin composite (labeled as S-Fe3O4/MXene/lignin@PU sponge) has been designed and prepared. The obtained superhydrophobic/superoleophilic PU sponge possesses excellent chemical stability, thermal stability, and mechanical durability in terms of being immersed in corrosive solutions and organic solvents and boiling water and being abrased by sandpapers, respectively. The oil adsorption capacities of the S-Fe3O4/MXene/lignin@PU sponge for various organic liquids range from 29.1 to 70.3 g/g, and the oil adsorption capacity for CCl4 can remain 69.6 g/g even after 15 cyclic adsorption tests. The separation efficiencies of the S-Fe3O4/MXene/lignin@PU sponge for n-hexane and CCl4 are higher than 98% in different environments (i.e., water, hot water, 1 mol/L NaOH, 1 mol/L NaCl, and 1 mol/L HCl). More importantly, the introduction of three light absorbers (i.e., Fe3O4, MXene, and lignin) into the S-Fe3O4/MXene/lignin@PU sponge shows a synergistic effect in the photothermal heat conversion performance, and the maximum surface temperature reaches 64.4 °C under sunlight irradiation (1.0 kW/m2). The separation flux of the S-Fe3O4/MXene/lignin@PU sponge for viscous LT147 vacuum pump oil reaches 35,469 L m-2 h-1 under sunlight irradiation, showing an increase of 27.3% compared to that of oil adsorption processes without the photothermal effect. Thus, the rational design of superhydrophobic sponges by introducing proper photothermal heat absorbers provides new insights into facile and cost-effective preparation of sponges for efficient oil/water separation.

Synthesis and Characterization of Biopolyol-Based Waterborne Polyurethane Modified through Complexation with Chitosan

In this study, a series of castor oil-based anionic waterborne polyurethane (CWPU) systems, which it has been suggested may be suitable for use as green elastomers with diverse applications in films and coatings, was prepared by modified with O-carboxymethyl chitosan (CS) as not only a reinforcing filler, but a chain-extender of polyurethane prepolymer to enhance the properties of polyurethanes. Moreover, not only was the system obtained with castor oil-based polyol in the absence of a catalyst, but it was maintained with low viscosity by using acetone instead of toxic methyl ethyl ketone (MEK) during the synthesis process. The sizes, zeta potential, chemical formation, and morphology of the CWPU-CS composites had been investigated by dynamic light scattering (DLS), infrared spectroscopy (IR), and scanning electron microscopy (SEM). Moreover, the results show that the modification allows to enhance storage/loss modulus, tensile properties, thermal stability at high temperature, and biocompatibility of CWPU and CWPU/CS nanocomposites according to various contents of CS.

Characterization and Properties of Water-Blown Rigid Polyurethane Foams Reinforced with Silane-Modified Nanosepiolites Functionalized with Graphite

In the present study, a promising flame retardant consisting of 80 wt% silane-modified nanosepiolites functionalized with 20 wt% graphite (SFG) is used to obtain a synergistic effect principally focussed on the thermal stability of water-blown rigid polyurethane (RPU) foams. Density, microcellular structure, thermal stability and thermal conductivity are examined for RPU foams reinforced with different contents of SFG (0, as reference material, 2, 4 and 6 wt%). The sample with 6 wt% SFG presents a slightly thermal stability improvement, although its cellular structure is deteriorated in comparison with the reference material. Furthermore, the influence of SFG particles on chemical reactions during the foaming process is studied by FTIR spectroscopy. The information obtained from the chemical reactions and from isocyanate consumption is used to optimize the formulation of the foam with 6 wt% SFG. Additionally, in order to determine the effects of functionalization on SFG, foams containing only silane-modified nanosepiolites, only graphite, or silane-modified nanosepiolites and graphite added separately are studied here as well. In conclusion, the inclusion of SFG in RPU foams allows the best performance to be achieved.