Low temperature-resistant superhydrophobic and elastic cellulose aerogels derived from seaweed solid waste as efficient oil traps for oil/water separation

Ulvan-based composite aerogels for efficient methylene blue adsorption

Developing polymer composite aerogels from macroalgae biomass efficiently eliminates water contaminants and mitigates the environmental issues associated with their disposal. We synthesized Ulvan and Ulvan/polyvinyl alcohol (Ulvan/PVA) composite aerogels employing a chemical crosslinking method utilizing borate ions and freeze-drying to enhance porosity. Ulvan/PVA composite aerogels were characterized through water solubility, SEM, FTIR, XRD, TGA and Brunauer, Emmett and Teller (BET) surface area measurements. The resultant Ulvan/PVA composite aerogels possess a resilient chemically cross-linked network with strong hydrogen bonds, significantly improving their mechanical and thermal properties. They exhibit a low density of 0.053 g/cm3, a surface area (BET) of 1.398 m2/g, and demonstrate exceptional mechanical properties with a strength of 4.7 MPa at 80 % strain. The synergistic effects of critical independent variables, including contact time and initial methylene blue (MB) concentration (1-20 mg/L), on MB adsorption capacity (mg/g) and removal efficiency (%) were optimized. The porous Ulvan/PVA composite aerogels demonstrated a strong affinity for methylene blue (MB), with a maximum adsorption capacity of 526.5 mg/g. The adsorption process was found to follow pseudo-second-order kinetics and was well described by the Langmuir isotherm model. Moreover, the adsorption capacity was investigated for three consecutive cycles, with 510, 496.54 and 483.26 mg/g in the first, second, and third cycles, respectively. The higher adsorption capacity of the adsorbent may be due to the synergistic interplay of electrostatic interactions, π-π conjugation, hydrogen bonding, and physicochemical properties. This synthesis strategy can provide an effective and facile pathway to prepare stable and porous polysaccharide-based composite aerogel with methylene blue (MB) uptake, reusability, and eco-friendliness as potential systems for pollutant treatment fields.

Facile and green fabrication of biodegradable aerogel from chitosan derivatives/modified gelatin as absorbent for oil removal

Frequent oil spills have caused increasingly severe pollution of marine water bodies. As a result, exploring green and efficient aerogels to tackles oil pollution is in high demand. In this work, a unique strategy for preparing all-biomass aerogel was innovatively proposed. A series of all-biomass CW&BW@DCGA aerogels were successfully prepared by multiple dynamic covalent bonding, in which carboxymethyl chitosan (CMCS) as the substrate material, modified gelatin (Gel-ADH) as a reinforcing agent, and dialdehyde β-cyclodextrin (Da-β-CD) as a non-toxic cross-linking agent. The resulting aerogels were further hydrophobically modified with a green and natural wax blend consisting of carnauba wax (CW) and beeswax (BW). The experimental results demonstrated that incorporating Gel-ADH significantly improved the elastic properties of the materials. Specifically, when m(CMCS):m(Gel-ADH) = 7:3, the aerogel exhibited outstanding resilience, with 60 % compressive strain. In addition, CW&BW@DCGA displayed excellent hydrophobicity, boasting a water contact angle as high as 148.6°, and impressive absorption capacities ranging from 31.7 to 62.5 g/g towards different oils. Its adsorption capacity remained close to 70 % after 10 cycles, indicating favorable reusability. The dynamic absorption processes towards gasoline, diesel, and soybean oil were also well fitted with the pseudo-second-order kinetic model, suggesting that the process is primarily governed by chemisorption.

Microwave/ultrasonic powered in-liquid plasma-assisted synthesis of 3D-hierarchical nanoporous network wheat-straw lignin/thiadiazole amide-modified cellulose sponge composite for oil-in-water emulsion separation and microbiological disinfection

Innovative super-hydrophilic/superoleophobic eco-friendly sponge composite is fabricated by integrating chemically-modified cellulose with lignin derived from bio-waste wheat-straw. Such combination is implemented by modifying cellulose with thiadiazole-amide and integrating it with lignin using microwave/ultrasonic-powered in-liquid plasma. Physicochemical characteristics of sponge-composite (WL-TDAC) are studied using FTIR, N2-physisorption, DLS, SEM, chemical-computational analysis, and surface wettability. In-liquid plasma irradiations inspire formation of abundant hydrogen bonds between cellulose and lignin, constructing highly negatively-charged sponge (ζAv = -36 eV) of developed surface character and 3D-hierarchical interconnected porous structure with a pore-size of ~2 nm. Sponge-composite displays underwater-oil-contact angles of 124° and 164.8° for n-hexane/water and dichloromethane/water mixtures, respectively, with water-contact-angle near 0°. Superhydrophilic-superoleophobic sponge powerfully separates light-oil/water and heavy-oil/water mixtures yielding water-permeation-fluxes of 8812.5 and 7500 L/m2/h, respectively, keeping separation-efficiencies >96 % for ten-cycles. Sponge-composite is a gorgeous disinfectant against hazardous bacteria/fungi. Cellulose-based lignin sponge seeds as promissory futuristic oil-in-water emulsion antimicrobial separator features for cleaning wastewater from oils and noxious microorganisms.

Mechanical Properties of Cellulose Aerogel Composites with and without Crude Oil Filling

Aerogels are an excellent alternative to traditional oil absorbents and are designed to remove oil or organic solvents from water. Cellulose-based aerogels can be distinguished as polymers that are non-toxic, environmentally friendly, and biodegradable. The compression measurement properties of aerogels are often evaluated using dry samples. Here, oil-soaked, hydrophobized cellulose aerogel samples were examined in comparison to dry samples with and without additional hemp fibers and various levels of starch for crosslinking. The samples were characterized by compression measurement properties and filmed to evaluate the regeneration of the sorbent with repeated use. Overall, the measurements of the mechanical properties for the dry samples showed good reproducibility. The Young's modulus of samples with additional hemp fibers is significantly increased and also shows higher strength than samples without hemp fibers. However, samples without hemp fibers showed slightly better relaxation after compression. Oil acts as a weak plasticizer for all aerogel samples. However, it is important to note that the oil does not cause the samples to decompose in the way unmodified cellulose aerogels do in water. Therefore, using hydrophobized cellulose aerogels as sorbents for oil in a sea or harbor with swell means that they can be collected in their entirety even after use.

Recent advances in hydrophobic nanocellulose aerogels for oil spill applications: A review

In a rapidly growing world, petroleum is used extensively in various industries, and the extraction, processing, and transportation of petroleum generates large amounts of petroleum-containing wastewater. Conventional oil/water separation methodologies are often ineffective and costly. Nanocellulose-based aerogels (NA) have emerged as a possible solution to this problem. However, hydrophobic modification is required for effective use in oil/water separation. This review on materials commonly used in these processes and outlines the requirements for adsorbent materials and methods for creating unique lipophilic surfaces. New trends in hydrophobization methods for NA are also discussed. Additionally, it includes the development of composite nanocellulose aerogels (CNAs) and cellulose based membrane specially developed for oil/water (o/w) separation considering different separation requirements. This analysis also examines how CNAs have evolved by introducing special properties that facilitate oil collection or make the adsorbent recyclable. We also discuss the difficulties in creating effective NAs for these important applications in a changing society, as well as the difficulties in creating oil recovery equipment for oil spill cleanup.

Superhydrophilic and Underwater Superoleophobic Copper Mesh Coated with Bamboo Cellulose Hydrogel for Efficient Oil/Water Separation

Super-wetting interface materials have shown great potential for applications in oil-water separation. Hydrogel-based materials, in particular, have been extensively studied for separating water from oily wastewater due to their unique hydrophilicity and excellent anti-oil effect. In this study, a superhydrophilic and underwater superoleophobic bamboo cellulose hydrogel-coated mesh was fabricated using a feasible and eco-friendly dip-coating method. The process involved dissolving bamboo cellulose in a green alkaline/urea aqueous solvent system, followed by regeneration in ethanol solvent, without the addition of surface modifiers. The resulting membrane exhibited excellent special wettability, with superhydrophilicity and underwater superoleophobicity, enabling oil-water separation through a gravity-driven "water-removing" mode. The super-wetting composite membrane demonstrated a high separation efficiency of higher than 98% and a permeate flux of up to 9168 L·m-2·h-1 for numerous oil/water mixtures. It also maintained a separation efficiency of >95% even after 10 cycles of separation, indicating its long-term stability. This study presents a green, simple, cost-effective, and environmentally friendly approach for fabricating superhydrophilic surfaces to achieve oil-water separation. It also highlights the potential of bamboo-based materials in the field of oil-water separation.