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.

Superhydrophobic nanohybrid sponges for separation of oil/ water mixtures

The industrial revolution has led to different types of environmental pollution, including frequent leakage of crude oil to marine waters and the contamination of wastewater with immiscible or emulsified oils and organic liquids from various industrial residues. Hence, developing multifunctional materials for oil/water separation is a field of high significance for the remediation of oil-polluted water. Recently, advanced superwetting materials have been employed for oily wastewater treatment. This review summarizes the recent development in fabricating superhydrophobic/superoleophilic nanohybrid polyurethane, melamine, and cellulose sponges for oil/water separation. The use of organic and/or inorganic nanohybrid materials opens the horizon for designing a diverse and wide range of superhydrophobic sponges due to the synergistic effect between the surface roughness and chemical composition. The discussion is organized based on different classes of low surface energy materials including thermoplastics, thermosets, elastomers, fluorinated polymers, conductive polymers, organosilanes, long alkyl chain compounds, and hydrophobic carbon-based materials. Recent examples for the separation of both immiscible and emulsified oil/water mixtures are presented, with a focus on fabrication strategies, separation efficiency, recyclability, mechanical performance, and durability. Currently, most studies did not focus on the mechanical/chemical stability of the fabricated sponges, and hence, future research directions shall address the fabrication of robust and long-term durable superhydrophobic sponges with proper guidelines. Similarly, more research focus is required to design superhydrophobic sponges for the separation of emulsified oil/water mixtures and heavy crude oil samples. Superhydrophobic sponges can be employed for treatment of oily wastewater, emulsion separation, and cleanup of crude oil spills.

Current Status of Cellulosic and Nanocellulosic Materials for Oil Spill Cleanup

Recent developments in the application of lignocellulosic materials for oil spill removal are discussed in this review article. The types of lignocellulosic substrate material and their different chemical and physical modification strategies and basic preparation techniques are presented. The morphological features and the related separation mechanisms of the materials are summarized. The material types were classified into 3D-materials such as hydrophobic and oleophobic sponges and aerogels, or 2D-materials such as membranes, fabrics, films, and meshes. It was found that, particularly for 3D-materials, there is a clear correlation between the material properties, mainly porosity and density, and their absorption performance. Furthermore, it was shown that nanocellulosic precursors are not exclusively suitable to achieve competitive porosity and therefore absorption performance, but also bulk cellulose materials. This finding could lead to developments in cost- and energy-efficient production processes of future lignocellulosic oil spillage removal materials.

Using polypropylene needle punch nonwoven sorbents as the interceptor for oil in static and dynamic water experiments

This work was to determine the impact of pore size and thickness of sorbents besides the influence of oil properties on the performance of sorbents used as an interceptor barrier for oils in Static and dynamic water experiments. polypropylene needle punch sorbents were used. SEM test showed the porous structure of sorbents. Oil sorption test investigated that with sorbents had same thickness N1 absorbed oil 8.89 g/g of soybean oil and 7.15 g/g of motor oil. Meanwhile, sorbents with the same pore size, N6 absorbed oil 6.11 g/g of soybean oil and 5.13 g/g of motor oil. All sorbents showed a retention rate of over 75% after 24 h of dripping. Dynamic oil spreading revealed that smaller pore size and higher thickness exhibited higher height wicking. The static performance experiment showed motor oil and soybean oil started to leak at 38 and 32 min for N1, then prolonged with reducing pore size with intercepting efficiency around 70% after 600 min for motor oil and 540 min for soybean oil. In comparison, The motor oil and soybean oil started to leak at 49 and 40 min for N4 and then prolonged with increased thickness with intercepting efficiency around 70% after 480 min for motor oil and 360 min for soybean oil. Under the dynamic experiment, oils spilled quicker with initial leakage of sorbents N3 and N6 at rate flow 55.65 ml/s for motor oil and soybean oil were (41 min, 36 min) and (50 min, 41 min) while intercepting efficiency was (99%, 98.40%) and (99.33%, 98.40%).

In-Situ Synthesis of Hydrophobic Polyurethane Ternary Composite Induced by Hydroxyethyl Cellulose through A Green Method for Efficient Oil Removal

Hydroxyethyl cellulose (HEC) was introduced to activate the surface of polyurethane (PU) sponge to successfully prepare a hydrophobic ternary composite PU/HEC/SiO₂. The hydrophobic layer of the composite was realized by in-situ polymerization of methyltriethoxysilane (MTES) onto the surface of PU sponge. The formation of a stable hydrophobic SiO₂ layer solved successfully the problem of ease of SiO₂ particles shedding from the composite. Moreover, the amphiphilic molecules produced by the hydrolysis of MTES monomers facilitated the preparation of hydrophobic materials by aqueous dispersion polymerization. Aqueous synthesis made the reaction process environmentally-friendly and pollution-free. The as-prepared composite PU/HEC/SiO₂ not only retains high porosity and low density of the PU sponge, but also considerably reduced the surface free energy and increased the surface roughness of the PU sponge. Therefore, outstanding hydrophobicity and high porosity endow the composite with excellent oil removal capability as a high-efficiency absorbent. Moreover, the hydrophobic composite that had absorbed oil could be regenerated easily by squeezing and recycling.

Sugar-benzohydrazide based phase selective gelators for marine oil spill recovery and removal of dye from polluted water

The synthesis of 3,4,5-tri-O-benzohydrazide based N-glycosylamines were characterized using NMR (¹H and ¹³C) and mass spectral analysis. Gelation properties of the synthesized molecules in different solvents and oils were studied and gelation was observed with minimum Critical Gelator Concentration (CGC) of 0.8% (w/v) in benzene. The free hydroxyl group of the sugar moiety, benzohydrazide and three alkyl chains present in all these compounds afford the collective driving forces for gelation. Phase-Selective Organo-Gelators (PSOGs) are molecules that can gel the oil selectively from the biphasic combination of oil and water and it is one of the good candidates for recovering oil in case of oil spill. It is observed that these gelators can be used as solid particles on a biphasic system consist of oil and water. It solidifies the oil selectively which can be taken out by means of the physical process. FT-IR and UV-Vis spectroscopy suggest that the driving forces for the gelation are hydrogen-bonding, π-π stacking and van der Waals interaction. The gels were studied using FE-SEM, DSC and rheological techniques. FE-SEM analysis shows that the formation of thin fibers and large wrinkle like aggregate structure in the gel state is due to the presence of different weak molecular interactions. The phase selection and gel-sol transition properties of these molecules confer their ability to absorb and release dyes with high efficiency.

Bioinspired Ultralight Inorganic Aerogel for Highly Efficient Air Filtration and Oil-Water Separation

Inorganic aerogels have been attracting great interest owing to their distinctive structures and properties. However, the practical applications of inorganic aerogels are greatly restricted by their high brittleness and high fabrication cost. Herein, inspired by the cancellous bone, we have developed a novel kind of hydroxyapatite (HAP) nanowire-based inorganic aerogel with excellent elasticity, which is highly porous (porosity ≈ 99.7%), ultralight (density 8.54 mg/cm³, which is about 0.854% of water density), and highly adiabatic (thermal conductivity 0.0387 W/m·K). Significantly, the as-prepared HAP nanowire aerogel can be used as the highly efficient air filter with high PM_2.5 filtration efficiency. In addition, the HAP nanowire aerogel is also an ideal candidate for continuous oil-water separation, which can be used as a smart switch to separate oil from water continuously. Compared with organic aerogels, the as-prepared HAP nanowire aerogel is biocompatible, environmentally friendly, and low-cost. Moreover, the synthetic method reported in this work can be scaled up for large-scale production of HAP nanowires, free from the use of organic solvents. Therefore, the as-prepared new kind of HAP nanowire aerogel is promising for the applications in various fields.