PDMS/magnetic lignin sponge for oil/water separation

Hierarchical 0D CuO Wrapped by Petal-like 2D ZnO: A Strategic Approach of Superhydrophobic Melamine Sponge toward Wastewater Treatment

In addressing the pressing environmental challenges posed by frequent oil spills, this work presents a novel approach of synthesizing a superhydrophobic three-dimensional (3D) porous melamine sponge (MS). CuO and ZnO nanoparticles were grown on the MS via a hydrothermal method to create MS/CuO/ZnO with multiscale hierarchical nanostructures. The resulting material exhibited a stable water contact angle of 155° through various tests. MS/CuO/ZnO demonstrated exceptional oil absorption capacities (40-145 g/g and 0.83-0.99 mL.cm-3), surpassing 98% efficiency in oil separation, and retained reusability for 10 cycles. Impressively, the sponge achieved successful separation of oil/water emulsions with a permeation flux of 14870 L m-2 h-1. The composite sponge, distinguished by its high photodegradation ability, can degrade both water- and oil-targeted pollutants under visible light irradiation from light-emitting diode (LED). With its remarkable attributes including superior oil absorption, excellent oil/water separation, mechanical resistance, and excellent photocatalytic ability, it exhibits considerable potential for applications in both wastewater treatment and large-scale marine oil spill response. The easily prepared MS/CuO/ZnO emerges as a versatile solution capable of addressing pressing challenges and marking a significant leap toward sustainable and impactful environmental remediation.

Fluorine-Functionalized Covalent Organic Framework Superhydrophobic Modified Melamine Sponge for Efficient oil-water Separation

Hydrophobic sponges have attracted significant interest in oil spills and water-oil separation as potential absorption materials due to their desirable absorptivity, selectivity, and elasticity. In this paper, a hydrophilic melamine sponge (MS) is transferred into a superhydrophobic sponge via polydimethylsiloxane (PDMS) modification followed by in situ growth of fluorine-functionalized covalent organic framework (denoted as TFA-COF) nanoparticles. Therefore, the PDMS@TFA-COF@MS sponge was successfully prepared for efficient oil-water separation. The resultant PDMS@TFA-COF@MS exhibits superhydrophobic properties with a water contact angle of 156.7°. The superhydrophobic sponge has selectivity adsorption for different organic solvents and oils from water as well as oil-water separation efficiency (96% after 30 cycles) and oil absorption capacity (12 646% after 30 cycles). Meanwhile, the PDMS@TFA-COF@MS sponge exhibits strong thermal stability and flame retardancy in addition to having exceptional resistance to chemical corrosion in acidic, alkaline, and salt solutions. Moreover, the surfactant-stabilized oil-in-water emulsion could be efficiently separated by the sponge. Therefore, the prepared superhydrophobic PDMS@TFA-COF@MS sponge demonstrates possible uses for long-life oil-water separation applications.

Facile Preparation of Photothermal Superhydrophobic Melamine Sponge Decorated with MXene and Lignin Particles for Efficient Oil/Water Separation, Fast Crude Oil Recovery, and Active Deicing

Frequent oil spills and the discharge of oily wastewaters have caused a serious threat to the environment, ecosystems, and human beings. Herein, a photothermal and superhydrophobic melamine sponge (MS) decorated with MXene and lignin particles has been prepared for the separation of oil/water mixtures, the recovery of crude oils, and active deicing. The obtained superhydrophobic melamine sponge shows a water contact angle (WCA) of 152.3° and an oil contact angle of ∼0° and possesses good chemical stability, thermal stability, and mechanical durability in terms of being immersed in various liquids (i.e., corrosive solutions, organic solvents, and boiling water) and being abrased by sandpapers. This superhydrophobic MS displays a high oil adsorption capacity of CCl4, up to 91.6 times its own weight and a high separation efficiency of 99.4%. Furthermore, the maximum surface temperature of the superhydrophobic MS reaches 57.5 °C under sunlight irradiation (1.0 kW/m2) due to the excellent photothermal heating conversion performance of MXene and lignin particles. When exposed to sunlight, the superhydrophobic MS can quickly absorb viscous crude oils up to 72 times its own weight. Also, the WCA of the superhydrophobic MS remains above 146° after 50 icing/deicing cycles, showing excellent photothermal anti-icing properties. Thus, this study presents an easy and low-cost method for designing photothermal superhydrophobic melamine sponges and opens a new avenue to the applications of efficient oil/water separation, fast crude oil recovery, and active deicing.

Porous lignin-based composites for oil/water separation: A review

Frequent oceanic oil spill incidents and the discharge of industrial oily wastewaters have caused serious threats to environments, food chains and human beings. Lignin wastes with many reactive groups exist as the byproducts from bioethanol and pulping processing industries, and they are either discarded as wastes or directly consumed as a fuel. To make full use of lignin wastes and simultaneously deal with oily wastewaters, porous lignin-based composites have been rationally designed and prepared. In this review, recent advances in the preparation of porous lignin-based composites are summarized in terms of aerogels, sponges, foams, papers, and membranes, respectively. Then, the mechanisms and the application of porous lignin-based adsorbents and filtration materials for oil/water separation are discussed. Finally, the challenges and perspectives of porous lignin-based composites are proposed in the field of oil/water separation. The utilization of abundant lignin wastes can replace fossil resources, and meanwhile porous lignin-based composites can be used to efficiently treat with oily wastewaters. The above utilization strategy opens an avenue to the rational design and preparation of lignin wastes with high-added value, and gives a possible solution to use lignin wastes in a sustainable and environmentally friendly way.