Fabrication of superhydrophobic Enteromorpha-derived carbon aerogels via NH4H2PO4 modification for multi-behavioral oil/water separation

Fabrication of straw-based graphene aerogels for oil/water separation: the effects of crude fiber fractions in straw

Benefiting from its abundance, eco-friendliness, and sustainability, crop straw is considered a promising candidate combined with graphene oxide (GO) to fabricate straw-based graphene aerogels (SGAs) for oil/water separation. However, considering the complex composition of straw, the roles played by different crude fibers in straw in the formation of SGAs are still unclear. Herein, wheat straw (WS) was used in this work and pretreated with acid and alkali to regulate its crude fiber fractions. Then, it was crosslinked with GO to fabricate various SGAs for comparing their differences in the formation, structure, and oil/water separation performance. Results indicated that acid can remove plentiful hemicellulose from the WS (from 29.9 ± 2.1 to 7.0 ± 0.8 wt%) while retaining most lignin and cellulose; alkali can retain cellulose (from 32.4 ± 3.6 to 70.6 ± 1.3 wt%) while greatly removing lignin and hemicellulose. Ascribed to high BET surface area and porous structure, the graphene aerogels formed by acid-/alkali-treated WS demonstrated superior oil absorption capacity (AC-WSGA: 62.3-126.0 g/g and AL-WSGA: 66.3-125.2 g/g). The poor mechanical compressibility of AC-WSGA was caused by the high lignin residue (16.2 ± 0.7 wt%) in AC-WS. The maximum compressive stress for AL-WSGA under 60% strain was 1.6 kPa, ensuring it achieved recoverable oil-absorbing properties by extrusion. The above findings suggested that cellulose and hemicellulose in straw contributed to the formation of SGAs with abundant porous and compressible architecture, whereas the presence of lignin greatly increased the brittleness of SGAs and decreased their oil removal and recycling performances.

Biomass-Based Sorbent with Superoleophilic from Ulva Prolifera for Oil Spill Cleanup

In this study, we demonstrate a new all bio-based adsorbent material by treating Enteromorpho prolifera (EP) fibers with tannic acid-ferric chloride complex and then grafting hydrophobic group octadecylamine. All raw materials are easily available, low-cost, and safe. The modified EP fibers have approximately 63.4 g g-1 of oil absorption and 1.4 g g-1 of water absorption, which is an 62.8% increase in oil absorption and an 82% increase in hydrophobicity over that of untreated EP fibers, respectively, exhibiting high hydrophobicity and oleophilicity. The affinity discrimination to water and oil enables hydrophobic algae candidate materials to separate oils and water efficiently, both in an oil-water mixture and a water-in-oil emulsion. In summary, the as-synthesized modified EP demonstrates a broad application prospect in the treatment of oil spill accidents and oily wastewater.

Biomimetic materials in oil/water separation: Focusing on switchable wettabilities and applications

Clean water resources are crucial for human society, as the leakage and discharge of oily wastewater not only harm the economy but also disrupt our living environment. Therefore, there is an urgent need for efficient oil-water separation technology. Surfaces with switchable superwetting behavior have garnered significant attention due to their importance in both fundamental research and practical applications. This review introduces the fundamental principles of wettability in the oil-water separation process, the basic theory of switchable wettability, and the mechanisms involved in oil-water separation. Subsequently, the review discusses the research progress, challenges, and issues associated with three conventional types of special wettability materials: superhydrophobic/superoleophilic materials, superhydrophilic/superoleophobic materials, and superhydrophilic/underwater superoleophobic materials. Most importantly, it provides a detailed exploration of recent advancements in switchable wettability smart materials, which combine elements of traditional special wettability materials. These include stimulus-responsive smart materials, pre-wetting-induced materials, and Janus materials. The discussion covers key response factors, detailed examples of representative works, design concepts, and fabrication strategies. Finally, the review offers a comprehensive summary of switchable superwetting smart materials, encompassing their advantages and disadvantages, persistent challenges, and future prospects.

Recent Advances in Biomass-Based Materials for Oil Spill Cleanup

Oil spill on sea surfaces, which mainly produced by the oil leakage accident happened on tankers, offshore platforms, drilling rigs and wells, has bring irreversible damage to marine environments and ecosystems. Among various spill oil handling methods, using sorbents to absorb and recover spill oils is a perspective method because they are cost-effective and enable a high recovery and without secondary pollution to the ecosystem. Currently, sorbents based on biomass materials have aroused extensively attention thanks to their features of inexpensive, abundant, biodegradable, and sustainable. Herein, we comprehensively review the state-of-the-art development of biomass-based sorbents for spill oil cleanup in the recent five years. After briefly introducing the background, the basic theory and material characteristics for the separation of oil from water and the adsorption of oils is also presented. Various modification methods for biomass materials are summarized in section three. Section four discusses the recent progress of biomass as oil sorbents for oil spill cleanup, in which the emphasis is placed on the oil sorption capacity and the separation efficiency. Finally, the challenge and future development directions is outlined.

Porous Carbon Sponge from White-Rot Fungus Phanerochaete chrysosporium for the Removal of Oils and Organic Solvents

Oil leakage incidentally occurs and leads to environmental disasters. Because of their porous and hydrophobic characteristics, graphene sponges are often studied as an oil adsorbent to repair oil spills at sea. Graphene materials are very expensive, and their biological toxicity has been given serious concerns; however, the easier preparation and eco-friendly, biomass-derived porous carbon materials can be used as an alternative to graphene materials. In this study, we prepared a porous carbon sponge (PCS) for oil and organic solvent removal by carbonizing white-rot fungus Phanerochaete chrysosporium, a fast-growing microorganism for the production of lignin-degrading enzymes and the environmental remediation. P. chrysosporium fungus balls were converted into black PCS by carbonization at high temperatures, where PCS was light (density of 56 g/L), hydrophobic (contact angle of 115°) and porous. According to the results of BET and XPS analysis, the surface area of PCS was 14.43 m²/g, and the carbon in PCS is mainly sp² carbon. PCS could adsorb pure oils and organic solvents within seconds. The adsorption capacities of PCS were 20.7 g/g for gasoline, 30.1 g/g for peanut oil, 27.7 g/g for toluene, 18.5 g/g for dodecane, 32.5 g/g for chloroform, 27.1 g/g for tetrahydrofuran, 23.7 g/g for acetone and 13.7 g/g for ethanol. According to the reusability study, there was no obvious capacity loss after recycling up to 10 cycles. Our results indicated that white-rot fungi could be adopted as a cheap carbon resource for oil and organic solvent removal.

Construction of a carbon nanosphere aerogel with magnetic response for efficient oil/water separation

A magnetic carbon nanosphere aerogel with high adsorption capacity was synthesized, which could realize positioning adsorption and rapid recovery.