Application of Nano-Hydroxyapatite Derived from Oyster Shell in Fabricating Superhydrophobic Sponge for Efficient Oil/Water Separation

The exploration of nonhazardous nanoparticles to fabricate a template-driven superhydrophobic surface is of great ecological importance for oil/water separation in practice. In this work, nano-hydroxyapatite (nano-HAp) with good biocompatibility was easily developed from discarded oyster shells and well incorporated with polydimethylsiloxane (PDMS) to create a superhydrophobic surface on a polyurethane (PU) sponge using a facile solution–immersion method. The obtained nano-HAp coated PU (nano-HAp/PU) sponge exhibited both excellent oil/water selectivity with water contact angles of over 150° and higher absorption capacity for various organic solvents and oils than the original PU sponge, which can be assigned to the nano-HAp coating surface with rough microstructures. Moreover, the superhydrophobic nano-HAp/PU sponge was found to be mechanically stable with no obvious decrease of oil recovery capacity from water in 10 cycles. This work presented that the oyster shell could be a promising alternative to superhydrophobic coatings, which was not only beneficial to oil-containing wastewater treatment, but also favorable for sustainable aquaculture.     

Facile fabrication of asphaltene-derived graphene-polyurethane sponges for efficient and selective oil-water separation

Based on the natural graphene-structure in the raw asphaltene material, a graphene-polyurethane sponge (GPU) oil-absorption material was prepared via a facile and inexpensive route of dip-coated sponge carbonization, which used low-value petroleum asphlatene as the dip-coating reagent and polyurethane sponges as the template. The GPU presents high hydrophobic and super oleophilic properties, as well as the excellent oil absorption performance. And its chloroform absorption capacity could reach 123 times its original mass, which is significantly higher than that of most reported oil absorbents. Furthermore, the GPU exhibits good recyclability. It has the promising applications in the pollution control of spilt oil.     

聚二甲基硅氧烷/微纳米银/聚多巴胺修饰的超疏水海绵的制备和应用

受海洋贝类生物黏附蛋白的启发,在碱性环境下利用多巴胺的自聚合性质,在聚氨酯海绵表面聚合活性聚多巴胺薄层,采用葡萄糖还原银离子进一步沉积微纳米银粒子构筑表面微纳结构,并水解聚二甲基硅氧烷前驱体对表面进行疏水改性,制备出了接触角大于150°的超疏水表面。利用接触角测定、扫描电子显微镜及能量弥散X射线谱和傅里叶红外光谱等技术手段对制备的改性海绵进行了表征,表明微纳米银粒子和硅甲基疏水基团被成功修饰到了海绵表面。改性海绵对有机溶剂和油类物质具有高选择性和高吸收性。吸收的有机溶剂和油类物质的质量能够达到其自身质量的12倍以上。饱和吸收后的海绵仅通过物理挤压即可将吸收的物质回收并使海绵恢复弹性和吸附能力,得到再生。该研究为油水分离和废油回收提供了一种经济、高效、环境友好的方案。     

Rapid Removal of Organics and Oil Spills from Waters Using Silicone Rubber “Sponges”

We have developed a simple, robust, and efficient technology utilizing cheap and recoverable materials based on commercially available silicone elastomer networks for removing organic solvents and crude oil from waters. Hydrophobic and oleophilic properties of silicone elastomers endow poly(dimethyl siloxane) (PDMS) with the capacity to absorb a large variety of organics, including benzene (B), toluene (T), ethylbenzene (E), and xylene (X), commonly referred to as BTEX, and also crude oils, while at the same time enabling the organic “sponges” to float on waters, which facilitates straightforward handling. We developed a method for generating PDMS particles with variable sizes (ranging from hundreds nanometers to few millimeters) by drop-wise depositing siloxane/cross-linker mixtures into warm water, a process which leads to the cross-linking of the PDMS components. We have tested the capability of the PDMS particles to remove toluene and benzene from water. We also performed similar experiments by utilizing PDMS sheets. In both instances we observed a rapid sorption of the organic phase into PDMS; the amount of absorbed organic solvent depended on the concentration in water and the total mass (volume) of PDMS and did not depend on the geometry of the PDMS “sponge.” In addition, we have examined the uptake of toluene and benzene from toluene/benzene (T/B) mixtures dissolved in water. Our results indicate that the amount of benzene absorbed from the T/B mixtures into PDMS increases relative to the uptake from pure benzene/water solutions. This behavior is associated with toluene acting as a “surfactant” that effectively replaces the more unfavorable PDMS/B contacts with less costly T/B ones. Finally, a simple experiment demonstrates qualitatively that PDMS is also capable of removing crude oils from oil-contaminated waters.     

Fabrication of superhydrophobic sponge with hierarchical structure and application for oil/water separation

Oil/water separation polyurethane sponge with hierarchically structured surface similar to the chemical/topological structures of lotus leaf has been successfully developed by combining mussel-inspired one-step copolymerization approach. The chemical structure, surface topography, and surface wettability of the sponge were characterized by FTIR, SEM, and contact angle experiments, respectively. The results showed that as-prepared sponge exhibited high oil absorption rate because of the expansion in oil and collapse in water of the polymer molecular brushes. Meanwhile, it also possessed high absorption capacity (20 times of the self-weight), high oil retention (93.7%), and good recyclability. It had excellent potential in practical applications.     

Graphene-based hemostatic sponge

Graphene-based sponge is a novel hemostatic material prepared by chemical cross-link of graphene oxide. It has a fast fluid absorption capacity to quickly absorb blood from wounds, activate clotting pathways, and achieve rapid hemostasis. In addition, graphene-based sponge is also a good platform carrier.It can be prepared by organic cross-linking, compounding with inorganic clay, and adding bioactive factors to enhance coagulation stimulation. By these methods, the hemostatic performance of the...     

Continuous separation of oil from water surface by a novel tubular unit based on graphene coated polyurethane sponge

We develop a new strategy for the continuous separation of oil from water surface using a novel tubular unit based on graphene coated polyurethane (P‐GEPU) sponge, and the P‐GEPU sponge was fabricated by a simple dip‐coating method; the as‐prepared sponges could adsorb different kinds of oil and organic liquids while repelling water. Moreover, the tubular unit was assembled by wrapping the P‐GEPU sponge on a porous PU hollow tube and combined with the accessories including pipes and joints. The tubular unit could float on the surface of water, and a continuous oil collection from water surface through vacuum pressure could be fulfilled, showing a high oil‐water separation efficiency (>96%). Finally, oil‐water separation efficiency remains above 93% after 10 cycles, exhibiting excellent reusability. In addition, our findings are easily scaled up, showing a great promise for large‐scale oil spill remediation.     

Durable multifunctional superhydrophobic sponge for oil/water separation and adsorption of volatile organic compounds

Inspired by the strong adhesion of mussels, a super-hydrophobic sponge was designed and prepared by a simple and inexpensive one-pot solution immersion method. The prepared superhydrophobic sponge can not only efficiently separate the oil–water mixture, more importantly, but also remove volatile organic compounds in the atmospheric environment. Polydopamine (PDA) enables polydivinylbenzene (PDVB) particles to be firmly and tightly attached to the melamine sponge skeleton, thereby making the hydrophilic sponge superhydrophobic and providing adsorption sites for volatile organic compounds in the air. The synergy enables the sponge/PDA/PDVB to quickly adsorb oils and organic substances, and it has high stability and capacity even after 20 cycles. In addition, superhydrophobic sponges can still perform outstanding adsorption performance even under highly acidic and alkaline environments. Meanwhile, the static adsorption capacity of the sponge/PDA/PDVB for gaseous toluene is 5.7 times that of activated carbon. Compared with pure PDVB, the super-hydrophobic sponge in the dynamic experiment has a penetration time increased from 6 to 390 min, which is 65 times longer than that of the PDVB, and the adsorption performance has been greatly improved. Therefore, our strategy may achieve a new effect, which can quickly and easily separate oil–water mixtures and remove volatile gaseous pollutants, and it can provide potential options for practical applications

     

Polyacrylonitrile/natural loofah sponge with spider web structure as a novel platform for enhanced oil adsorption

Three-dimensional, inexpensive and environmentally friendly adsorbent materials were urgently in demand for the absorption of organic compounds. In this study, the 3D ultralight sponge was assembled from fragmented electrospun nanofibers of polyacrylonitrile (PAN) and natural loofah. The PAN nanofibers and loofah short fibers were dispersed in an aqueous solution using polyvinyl alcohol (PVA) as the adhesive, and then formed the 3D ultralight sponge by freeze-drying technology. By adjusting the content of loofah, a kind of spider web structure which was beneficial to enhance oil adsorption was developed arising from polymers dissolution and reconstruction. At the same time, the loofah was integrated with the PAN by -OH···N≡C- hydrogen bonds to stabilize the structure. Finally, due to the high porosity (99.3%), low density (7.63 kg/m³) and unique spider web structure, our prepared PAN/loofah sponges could absorb organic compounds up to 177 times of their own weight. Hence, the developed PAN/loofah sponge as an environmentally friendly adsorbent would be promising in wastewater treatment.     

A Layered Chitosan/Graphene Oxide Sponge as Reusable Adsorbent for Removal of Heavy Metal Ions

Along with the growing severity of environment problem and energy crisis, it is inevitable to develop novel materials, which are contributed to the removal of hazardous pollutants from contaminated water. Herein, we reported a fhcile method for the preparation of free-standing chitosan/graphene oxide(CS/GO) composite sponges with low density, where CS/GO mixtures were first synthesized by tlie homogeneous reaction of chitosan and graphene oxide in aqueous acetic acid solution;then CS/GO sponges were obtained by lyophilizing the suspension, which were prefrozen at -20 ℃ and in liquid nitrogen successively. The obtained layered sponge showed good water- driven shape memory effect and was a good adsorbent of Co^2+ and Ni^2+ witli a large adsorption capacity of 224.8 and 423.7 mg/g, respectively. Importantly, the successive adsorption-desorption studies employing CS/GO sponge indicated that the composite could be regenerated by HC1 solution and reused in more than five cycles with regeneration efficiency beyond 80%. Also, the resultant sponge was explored as an exceptionally adsorbent for the removal of organic dye(e.g., methylene blue, MB).     

Effective removal of cation dyes from aqueous solution using robust cellulose sponge

Cellulose sponge was proposed to an attractive bio-absorbent owing to its highly efficient, low-cost, biodegradable, and renewable sourcing. In this work, the wasted cotton linter as raw materials, the highly porous and lightweight cellulose sponges were synthesized via a facile chemical crosslinking and freeze-drying process. The resultant cellulose sponge (CA) exhibited an interconnected three-dimensional porous structure through crosslinked with N,N′-methylene bisacrylamide (MBA), which was beneficial to remove organic dyestuffs. The effects of various factors including solution pH, contact time, initial dye concentration, and ionic strength on the adsorption behavior were investigated in detail. Herein, Langmuir isotherm models were selected to determine the adsorption capacity, and the maximum theoretical adsorption capacity for Methylene blue (MB) and Crystal violet (CV) was 123.46 and 76.63 mg/g, respectively. Particularly, the results of kinetic and thermodynamic tests showed that the adsorption performance was a spontaneous endothermic reaction and the adsorption process followed the pseudo-second-order kinetic. Furthermore, cellulose sponges could maintain maximum adsorption capacity even after twelve cycles. Therefore, the eco-friendly cellulose sponge would be a promising adsorbent for effective wastewater treatment.     

Chloramphenicol collagen sponges for local drug delivery in dentistry

Drug delivery systems based on natural drug carriers have become important due to their non-toxicity and biodegradability. We report here the synthesis and characterization of new biomaterials like sponges containing collagen, chloramphenicol and glutaraldehyde for dentistry. All sponges favour water absorption, showing that increasing the glutaraldehyde content leads to an increase in water uptake. The sponges showed resistance to collagenase degradation and strong activity against the tested bacteria. Kinetic data showed non-Fickian diffusion behaviour with a slow release rate. Taking into account that dental drug delivery systems exhibit low water absorption, slow drug release, high content of drug delivery, good antimicrobial activity, and resistance to enzymatic action, the results obtained in this study indicate the optimal content of glutaraldehyde for the sponge as being 0.5%. The properties of the designed formulations demonstrate that these sponges could be adequate for the treatment and/or the prophylaxis of infected lesions at the dental level.     

Evaluation of the use of liquid dishwashing compounds to control bacteria in kitchen sponges

A test procedure for evaluating the effect of adding commercial liquid hand dishwashing detergents to kitchen sponges to control microbial growth is described. Claims for this type of application are being made on dishwashing detergents throughout the world. In this evaluation, commercially available kitchen sponges were stripped of antimicrobial compounds. Sponges were then inoculated with a pool of 7 microorganisms which consisted of gram positives, gram negatives, and yeast. Inoculated sponges were treated with the detergent as recommended by the manufacturer and allowed to incubate for 16 h at ambient temperature. Surviving microorganisms were then quantitated using either the spiral or pour plate method. Tests were run using both clean sponges and sponges soiled with 0.5% nonfat dry milk (NFDM). Untreated sponges showed stasis or slightly increased bacterial populations after the incubation period in the absence of NFDM. Significant increases of up to 3 log cfu/mL were observed for untreated sponges when soiled with NFDM. Statistically significant reductions were observed for clean sponges (99.8-99.9998%) and sponges soiled with NFDM (87.6-99.9%) when detergents making "antibacterial sponge" claims were added to the inoculated sponges. Statistically significant differences between detergents making "antibacterial sponge" claims were also observed.     

Hydrophobic,superabsorbing materials from reduced graphene oxide/MoS2 polyurethane foam as a promising sorbent for oil and organic solvents

This study illustrates the preparation of robust superhydrophobic and superoleophilic reduced graphene oxide (rGO) and MoS₂ nanoparticles incorporated polyurethane (PU) foam by in-situ polymerization via the one-shot method. Spectroscopic analyses confirmed the successful formation of nanoparticles and also the development of the hybrid PU material. The sponges were evaluated based on hydrophobicity and oil absorbance capacities and the modified foam exhibits the water contact angle of 151°. The pore size of the foam analyzed using an optical microscope and the effect on the density and porosity were also analyzed. The oil absorption capacity of the foam was studied using standard sorption testing. The oil and organic solvent selectivity and recyclability of hybrid PU foam were performed to estimate whether the foams could be recycled and reused. The modified system shows very high selectivity (83–94%). The recyclability of the foam was about 35 cycles without much reduction in its own weight and after 55 cycles more than 80% of the oil absorption capacity was conserved. The resulting hybrid PU material is highly efficient, porous, ultralight, hydrophobic and reusable sorbent material and displays great potential for versatile environmental remediation.     

石墨烯基海绵在止血领域的研究进展

石墨烯基海绵是一类新型的外伤止血材料, 由二维纳米片层构筑形成, 具有多级孔道结构、 快速液体吸收能力及易于表面功能化等特性, 可作为平台式载体实现多功能复合, 在外伤止血领域表现出良好的应用前景. 本文对石墨烯基海绵的外伤止血应用与机制研究进行了综述, 并对其发展前景进行了展望.     

Three-dimensional interconnected microporous poly(dimethylsiloxane) microfluidic devices

This technical note presents a fabrication method and applications of three-dimensional (3D) interconnected microporous poly(dimethylsiloxane) (PDMS) microfluidic devices. Based on soft lithography, the microporous PDMS microfluidic devices were fabricated by molding a mixture of PDMS pre-polymer and sugar particles in a microstructured mold. After curing and demolding, the sugar particles were dissolved and washed away from the microstructured PDMS replica revealing 3D interconnected microporous structures. Other than introducing microporous structures into the PDMS replica, different sizes of sugar particles can be used to alter the surface wettability of the microporous PDMS replica. Oxygen plasma assisted bonding was used to enclose the microstructured microporous PDMS replica using a non-porous PDMS with inlet and outlet holes. A gas absorption reaction using carbon dioxide (CO(2)) gas acidified water was used to demonstrate the advantages and potential applications of the microporous PDMS microfluidic devices. We demonstrated that the acidification rate in the microporous PDMS microfluidic device was approximately 10 times faster than the non-porous PDMS microfluidic device under similar experimental conditions. The microporous PDMS microfluidic devices can also be used in cell culture applications where gas perfusion can improve cell survival and functions.     

Rapid hemostasis and excellent antibacterial cerium-containing mesoporous bioactive glass/chitosan composite sponge for hemostatic material

Rapid and effective hemostasis is key to controlling bleeding and reducing mortality. Here, a composite hemostatic sponge (Ce-MBG/CHT) of cerium-containing mesoporous bioactive glass (Ce-MBG) and chitosan (CHT) was prepared by a freeze-drying technique and compared with the commercially available gelatin sponge (GS), to further evaluate the hemostatic performance of composite sponge materials. The results indicate that the pore structure, porosity, and water absorption of the sponge improved following the addition of Ce-MBG. Whole blood coagulation studies suggested that Ce-MBG/CHT has superior hemostatic properties to GS and validated in vitro thrombosis, platelet adhesion and blood compatibility. In vitro coagulation studies showed that factor XII was activated by the addition of Ce-MBG, inducing the intrinsic coagulation pathway. Furthermore, we evaluated the cytocompatibility of samples after contact with L929 cells for 24, 48, and 72 h via the cytotoxicity test. Compared with GS, 4Ce-MBG/CHT was more efficient against E. coli and S. aureus. All these results indicate that Ce-MBG/CHT sponges are likely useful for rapid hemostasis.     

Design of a Waste Paper-Derived Chemically ‘Reactive’ and Durable Functional Material with Tailorable Mechanical Property Following an Ambient and Sustainable Chemical Approach

Controlled tailoring of mechanical property and wettability is important for designing various functional materials. The integration of these characteristics with waste materials is immensely challenging to achieve, however, it can provide sustainable solutions to combat relevant environmental pollutions and other relevant challenges. Here, the strategic conversion of discarded and valueless waste paper into functional products has been introduced following a catalyst-free chemical approach to tailor both the mechanical property and water wettability at ambient conditions for sustainable waste management and controlling the relevant environmental pollution. In the current design, the controlled and appropriate silanization of waste paper allowed to modulate both the a) porosity and b) compressive modulus of the paper-derived sponges. Further, the association of 1,4-conjugate addition reaction between amine and acrylate groups allowed to obtain an unconventional waste paper-derived chemically ‘reactive’ sponge. The appropriate covalent modification of the residual reactive acrylate groups with selected alkylamines at ambient conditions provided a facile basis to tailor the water wettability from moderate hydrophobicity, adhesive superhydrophobicity to non-adhesive superhydrophobicity. The embedded superhydrophobicity in the waste paper-derived sponge was capable of sustaining large physical deformations, severe physical abrasions, prolonged exposure to harsh aqueous conditions, etc. Further, the waste paper-derived, extremely water-repellent sponges and membranes were successfully extended for proof-of-concept demonstration of a practically relevant outdoor application, where the repetitive remediation of oil spillages has been demonstrated following both selective absorption (25 times) of oils and gravity-driven filtration-based (50 times) separation of oils from oil/water mixtures at different harsh aqueous scenarios.     

Preparation of superhydrophobic materials for oil/water separation and oil absorption using PMHS–TEOS-derived xerogel and polystyrene

Fabrication of suerhydrophobic materials towards oil/water separation and oil absorption has been receiving great attention nowadays, due to the significant increase of industrial oily wastewater and frequent accident of oil spill. In most previous studies, the usage of expensive precursors restricted the wide applications of prepared superhydrophobic materials. In this work, superhydrophobic filter paper, fabric and polyester sponges were fabricated by dip-coating the mixed solution of polystyrene and xerogels, which were prepared with tetraethoxysilane and polymethylhydrosiloxane, based on previous work. The as-fabricated fabric can effectively separate oil and water mixtures and possesses excellent reusability; more significantly, the materials maintained its good hydrophobic and excellent oil/water separation capacity even after ten cycles. Interestingly enough, the stability was provided, as a result, the fabric still exhibited superhydrophobic after 100 abrasion times and showed high repellency towards many liquids with different pH values. Additionally, the coated polyester sponges can quickly absorb various oil and organic liquid, which will offer a practical application for the treatment of seawater or oily wastewater. By contrast, this experiment process is simple and avoided using costly fluoro-chemicals or complicated fabrication process.     

Facile synthesis of microfibrillated cellulose/organosilicon/polydopamine composite sponges with flame retardant properties

Cellulose composite sponges with good mechanical, heat-insulating and flame retardant properties were constructed by a facile method. Simultaneous polymerization of dopamine and hydrolysis of organosilicon in the suspension of microfibrillated cellulose could provide the stiffness and flame ratardancy of the composite sponges. The hybrid sponges had low density (15.1–28.5 mg/cm³) and desirable compression strength (76.6–135.8 kPa). Scanning electron microscopy (SEM) and thermal conductivity tests revealed that the sponges are composed of a three-dimensional cellulosic network and the porous structure endowed them low thermal conductivity [~0.046 W/(m K)]. With the addition of organosilicon (45 wt%) and polydopamine (PDA) (10 wt%), a 456% improvement in BET surface area of the sponge could be achieved. The limiting oxygen index (LOI) of the composite sponge could be as high as 29.5 with 15 wt% PDA and could self-extinguish at once when it was removed from torch. That was owing to the promoted materials carbonization ability of silicon and radical scavenging activity of dopamine.