Natural microfibrils/regenerated cellulose-based carbon aerogel for highly efficient oil/water separation

Superhydrophobic-Activated Carbon Coating: A Path toward Demulsification and Separation of Crude Oil Emulsions

The emissions of oily wastewater represent a considerable risk to the environment. The demulsification and separation of crude oil emulsions have been difficult problems in the field of petroleum. Consequently, the development of green, cost-effective, and highly efficient demulsification and/or oil-water separation technologies has emerged as a critical research priority. In this study, activated carbon (AC) was designed to be modified by using hexadecyltrimethoxysilane (HDTMS) as a superhydrophobic material. By spraying a mixture of the superhydrophobic AC and epoxy resin onto 300# and 2000# stainless steel mesh (SSW), superhydrophobic AC-coated SSWs with excellent wetting resistance and durability were developed. These superhydrophobic AC-coated SSWs completely replaced demulsifiers for achieving the separation of crude oil emulsions. The 300# AC-coated SSW demonstrated a remarkable separation efficiency above 96.6% across five types of oil-water mixtures. For chloroform-water mixtures, the separation efficiency and flux consistently remained above 97.7% and 12050 L·m-2·h-1 over 20 consecutive separation cycles. The 2000# AC-coated SSW also demonstrated stable separation efficiency and flux of 94.8% and 490.8 L·m-2·h-1 for the separation of water-in-chlorobenzene (W/O) emulsions after 20 consecutive cycles. This underscores the material's consistent high performance in oil/water separation processes. The strategy of the separation materials may provide a general hydrophilic modification method for a new generation of high-performance superhydrophobic activated carbon coatings and offers a prospective technical support for the efficient and rapid separation and purification of oily wastewater.

Hydrophobic cellulose nanofiber based aerogel for high-efficiency oil-water separation

Hydrophobic aerogel has emerged as an effective material for oil absorption. In this study, we fabricated four types of hydrophobic nanocellulose (NC)-based aerogels through a freeze-drying method with methyltrimethoxysilane (MTMS) surface modification for enhanced oil removal. It involved tuning the functional groups of NC (cellulose nanofibers (CNF) and TEMPO-oxidized cellulose nanofibers (TCNF)) and selection of crosslinkers (polyethyleneimine (PEI) and tannic acid (TA)). Among the developed aerogels, TCNF-PEI exhibited a homogeneous, hierarchical 3D scaffold with notably high porosity, as evidenced by SEM analysis. FTIR and XRD confirmed the formation of crosslinked networks through hydrogen bonds, electrostatic interactions, covalent bonds and physical entanglement. TCNF-PEI exhibited superior absorption capacity of 112.30 g/g, nearly twice of CNF-PEI (62.93 g/g), and three times in comparison with CNF-TA (44.67 g/g) and TCNF-TA (48.05 g/g), respectively. The absorption kinetics followed the pseudo-second-order model. Moreover, TCNF-PEI exhibited a wide temperature applicability and retained absorption capacity of above 74 % after five cycles. The developed TCNF-PEI aerogel also showed excellent sorption capacities (85.6-148.7 g/g) for a variety of oils and organic solvents. The significant enhancement in absorption capacity, superior reusability and applicability indicated that TCNF-PEI aerogel can be a candidate of emergency treatment for rapid oil spill recovery, particularly from port operations or maritime shipping.

An Optimized Aerogel-Based Apheresis Device for Targeted Lipid Clearance in Elderly Hyperlipidemia Patients

Elderly patients with hyperlipidemia often exhibit resistance to conventional hypolipidemic treatments, underscoring the need for more effective strategies to address lipid imbalances in this high-risk group. This study introduces LipClean, an aerogel-based apheresis device specifically designed to remove harmful plasma lipids. LipClean is constructed using hydrophilic cellulose fibers, which serve as a supramolecular platform for synthesizing hydrophobic conjugated polymers through a Sonogashira-Hagihara reaction. These conjugated polymers are then cross-linked with the cellulose fibers via phosphorylation, generating an aerogel monolith with an interpenetrating network of hydrophilic fibers and hydrophobic polymers. Unlike bilayer aerogels that separate hydrophilic and hydrophobic layers, LipClean's interpenetrating structure is precisely engineered through polymer design and gradient cross-linking. This optimization enhances both bodily fluid flow and lipid adsorption while minimizing the removal of essential plasma components and ensuring unobstructed cell passage. In preclinical testing, LipClean significantly reduced triglyceride and cholesterol levels in an elderly rat model of hyperlipidemia and normalized lipid levels in blood samples from hypertensive patients. Importantly, purified blood maintained normal levels of blood cells and physiological and biochemical indicators after apheresis, highlighting LipClean's potential for managing hyperlipidemia-related disorders. This study, therefore, underscores the importance of interdisciplinary collaboration in driving medical device innovation.

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.

Development of a superhydrophobic and superoleophilic halloysite nanotube/phenyltriethoxysilane-coated melamine sponge sorbent material with high performance in supercritical CO2 atmosphere for the selective and effective oil spill cleanup and oil-water separation

In this study, activated halloysite nanotube (HNT) and phenyltriethoxysilane (PTES) were utilized for the first time to fabricate modified HNT materials and coat them onto melamine sponge (MS) substrate in the supercritical carbon dioxide (scCO2) atmosphere. The successful coating of MS substrate was confirmed using SEM, EDS, XPS, and contact angle measurements. The drainage technique applied in the CO2 medium achieved the uniform coating of both the inner and outer surfaces of the MS. Water and oil contact angles of the fabricated sorbent material (MS-PTES) were measured as 167.1° and 0°, respectively. MS-PTES sorbent having superhydrophobic and superoleophilic properties demonstrated sorption capacities ranging from 47.6 g/g to 132.2 g/g for 13 different pollutants, including various petroleum products, oils, and organic solvents. Moreover, the MS-PTES sorbent material showed outstanding separation efficiency (99.99%) for the diesel-water mixture using a continuous separation process. It also displayed high selectivity for oil and organic solvent pollutants under acidic, saline, and alkaline conditions, along with excellent reusability, chemical stability, robustness, and mechanical flexibility. MS sorbent material coated with HNT-modified PTES nanoparticles, produced in the scCO2 atmosphere using the drainage technique, represents a promising solution for the removal of petroleum derivatives, oils, and organic solvents from water.

A review of various dimensional superwetting materials for oil-water separation

In recent years, the application and fabrication technologies of superwetting materials in the field of oil-water separation have become a research hotspot, aiming to address challenges in marine oil spill response and oily wastewater treatment. Simultaneously, the fabrication technologies and related applications of superwetting materials have been increasingly diversified. This paper systematically reviews the sources and hazards of oily wastewater and oil-water emulsions, several traditional oil-water separation methods, and their limitations, thereby highlighting the advantages of superwetting materials. Additionally, this paper provides an overview of the fundamental theories of wetting and conducts a microanalysis of the penetration mechanism based on Laplace pressure at the gas-liquid-solid three-phase interface. Following this, the latest advances in superwetting oil-water separation materials are elucidated, focusing on five categories: (i) superhydrophobic-superoleophilic materials; (ii) superhydrophilic-underwater superoleophobic materials; (iii) superhydrophobic-superoleophobic materials; (iv) "special" superwetting materials; and (v) smart switchable superwetting materials. This paper innovatively discusses these materials from the perspectives of two-dimensional and three-dimensional materials, deeply studying the mechanisms of oil-water separation and using data to quantify the separation efficiency. Comparative discussions are conducted on the materials from various dimensions, including different substrates, innovations in existing technologies, and fabrication methods as discussed in various articles, followed by corresponding summaries. Finally, the existing shortcomings and challenges of current superwetting materials are summarized, and prospects are proposed. We firmly believe that developing low-cost, stable, environmentally friendly, and practical large-scale superwetting oil-water separation materials will have broad application prospects and potential in the future.

Biomass-activated carbon-based superhydrophobic sponge with photothermal properties for adsorptive separation of waste oil

The increasing discharge of oily wastewater from life poses a serious threat to the ecological environment and human health. To develop green, efficient, and low-cost materials for oil-water separation, a superhydrophobic photothermal oil-absorbing sponge (CAC-PDA@MF) was prepared by using nanoscale coconut shell activated carbon (CAC) loaded on a melamine sponge in this study. The sponge had excellent superhydrophobicity (WCA of 159.53°) due to the reduction of surface energy by grafting long-chain silanes. The adsorption capacity of the sponge was 69.04 g/g-158.27 g/g for a wide range of oils and organic solvents, and the sponge had excellent mechanical properties for multiple adsorption and recovery of oil. After 50 cycles of oil-water separation, its separation efficiency was maintained at over 98 %. In addition, the material had high acid, alkali, and salt resistance as well as excellent photothermal conversion properties. Its surface temperature rose rapidly to 100 °C and above, at a light intensity of 1.0 kW/m2. The material was capable of adsorbing and recovering high-viscosity oils that were solid or semi-solid at room temperature. Its versatility and commercial value made it a promising candidate for a wide range of applications.

One-Pot Synthesis of Cellulose-Based Carbon Aerogel Loaded with TiO2 and g-C3N4 and Its Photocatalytic Degradation of Rhodamine B

A cellulose-based carbon aerogel (CTN) loaded with titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) was prepared using sol-gel, freeze-drying, and high-temperature carbonization methods. The formation of the sol-gel was carried out through a one-pot method using refining papermaking pulp, tetrabutyl titanate, and urea as raw materials and hectorite as a cross-linking and reinforcing agent. Due to the cross-linking ability of hectorite, the carbonized aerogel maintained a porous structure and had a large specific surface area with low density (0.0209 g/cm3). The analysis of XRD, XPS, and Raman spectra revealed that the titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) were uniformly distributed in the CTN, while TEM and SEM observations demonstrated the uniformly distributed three-dimensional porous structure of CTN. The photocatalytic activity of the CTN was determined according to its ability to degrade rhodamine B. The removal rate reached 89% under visible light after 120 min. In addition, the CTN was still stable after five reuse cycles. The proposed catalyst exhibits excellent photocatalytic performance under visible light conditions.

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.