Abstract
The leakage of industrial oil and organic solvents can wreak great harm to the environment and ecology. Therefore, development of a low-cost and high-performance adsorption material to solve this problem is crucial. The modification of sponge materials has become a “hot topic” in oil/water separation. We employed mild heat treatment to fabricate a superhydrophobic melamine sponge (SMS) with a water contact angle of ≤168 ± 5°. The hydrophobicity of the SMS originated from the decreased surface energy, which was due to the elimination of hydroxyl groups, and adsorbed water and ammonia in the pristine melamine sponge (MS). The prepared SMS possessed superhydrophobicity, excellent elasticity, high porosity, low density and excellent efficient oil/water separation performance. The obtained SMS also had great compressive durability and cyclic properties. Moreover, the SMS could maintain excellent adsorption performance for various oils and organic solvents over 50 cycles by squeezing and exhibited extremely high separation efficiency of ≤4.5 × 10 L m−3 h−1 in turbulent and non-turbulent oil/water systems. Thus, this SMS could be a candidate for large-scale recovery of oil or organic solvents from water resources.
You have access to this article
Please wait while we load your content... Something went wrong. Try again?
About
Cited by
Related
Download options Please wait...
Article information
Article type Paper
New J. Chem., 2019,, 6343-6349
BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS
A superhydrophobic and elastic melamine sponge for oil/water separation
Y. Zhang, Q. Zhang, R. Zhang, S. Liu and Y. Zhou, New J. Chem., 2019, , 6343 DOI: 10.1039/C9NJ00447E
If you are provided correct acknowledgement is given.
If you are
Social activity
Fetching data from CrossRef.
This may take some time to load.
Loading related content
The pre-washing unit VWE 600/2 combines the function of a heavy material separator with a pre-wash of the feeding material. The Herbold pre-washing unit separates foreign bodies such as stones, metals, glass, sand and paper using three different integrated process steps. The feed material undergoes an intensive washing step and then, in a third step, makes further foreign materials sink.
8c71620b48908498-FRA
UTC time
Browser: Mozilla/5.0 (Windows NT 6.1; rv:63.0) Gecko/20100101 Firefox/63.0
• Workforce_operations/state_human_resource_management/for_state_personnel_system_hr_practitioners/attendance_and_leave/leave_audits_transfers_and_payouts
Research suggests that eight out of 10 dogs find it hard to cope when left alone. Yet, half won't show any obvious signs and so it can be easy for owners to miss. The good news is that separation anxiety (SRB) is preventable and treatable.
A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity.
My job uses texting for way more communication than it probably should, and I desperately need a way to separate them from personal conversations with friends and family. I really don't even use my phone for that anymore because of work and how exhausting just opening the messages app has become. Getting a second phone isn't an option though, and I'd rather not deal with the hassle of moving anything to a new number. There are too many messages I need to go back to throughout the week so just archiving them isn't really what I'm looking for.
EDIT [3/8/21]: So I tried SMS Organizer and Pulse to see if either of those met my needs. Maybe I'm missing something, but neither really had what I am looking for.
SMS Organizer doesn't really seem to be any better than default Messages, tbh. No folders or filters. It only sorts out regular texts from like promotional and spam texts. Am I missing something?
Pulse was a little better. It at least has folders to sort conversations into, but there's no way to start the app in a specific folder or set downtime for certain folders. I'm kinda wanting to avoid all of my work texts being the first things I see when I open my texts. Plus, it looks like I have to manually categorize individual threads instead of being able to select contacts that would always be in that category.
The hunt continues...
Любимый, мы обязательно скоро встретимся, я каждый день о тебе думаю и с нетерпеньем жду, когда мы будем вместе! Спасибо за то, что даже на расстоянии даришь мне любовь и заботу!
Я так хочу быть рядом,
Всегда возле тебя.
Так жду, когда обнимешь,
С заботой и любя!
Пройдет скорее время
И встретимся мы вновь.
Подаришь ты мне сказку,
Эмоции, любовь!
Милый мой, с тобой в разлуке
Суждено нам быть сейчас.
Вспоминаю твои руки,
Нежный взгляд я каждый час.
Встречи жду, супруг любимый,
И все мысли о тебе,
Самый важный, несомненно,
Человек в моей судьбе.
Я скучаю милый мой,
Возвращайся ты домой.
Хочу видеть тебя скоро,
Ты надежная опора.
Скучаю, время тороплю,
Ведь очень я тебя люблю.
Хочу к тебе я побежать,
И крепко вновь тебя обнять.
Муж, ну как я без тебя?!
Самый милый для меня,
Самый лучший и родной,
Хорошо мне так с тобой!
Без тебя же очень грустно,
Пусто дома и не нужно
Никаких других людей,
Возвращайся поскорей!
Тяжела наша разлука,
Я страдаю, милый мой!
Без тебя мне очень туго,
Муж любимый и родной!
Дни считаю, предвкушаю
Нашу встречу, очень жду.
Я тоскую, я скучаю,
Себе места не найду!
Муж, в разлуке мы с тобой...
Да, период не простой
Выпал в жизни, я грущу
И к тебе скорей хочу!
Мне обнять тебя бы крепче,
Чтоб на сердце стало легче.
Я скучаю, встречи жду,
Милый муж, тебя люблю!
Каждый день без тебя — это долгие часы ожидания и тоски. С нетерпением жду встречи. Мечтаю как можно скорее встретиться с тобой взглядом, вдыхать твой запах и бесконечно обнимать тебя, мой дорогой супруг!
Когда мы разлучаемся, я сижу на подоконнике, укутавшись в плед. Все мои мысли о тебе, а в руках фото с нашей свадьбы. Это самое грустное время для меня. Сквозь города моя душа стремится к тебе с любовью.
Муж, с тобой мы расстаемся,
Ты уедешь далеко...
Мне же только остается
С тем смириться. Нелегко
Мне дается это, милый,
Буду очень я скучать!
Буду ждать тебя, любимый,
Нашу встречу предвкушать!
Who needs a SHPE?
• Service members on active duty for 180 days or more of continuous service
• Reserve Component members on AD orders for 180 days or more of continuous service
• RC on AD orders for 31 days or more in support of a contingency operation
Greater than 180 days before separation/retirement:
• Complete DD Form 2870 and fax to 402-294-8490.
• Filing a VA claim: Begin preparing for the claim process. Contact local VA rep.
• Not filing a VA claim: No action needed at this time.
180-90 days before separation/retirement:
Filing a VA claim: Not filing a VA claim:Less than 90 days prior to separation/retirement:
• SHPE will need to be completed at MTF.
• A VA claim can still be processed; however, any VA exams conducted cannot take the place of the SHPE. These exams may not be completed prior to separation, delaying your access to benefits.
Steps to completing your SHPE at the MTF:
• Complete audiogram (if indicated on the My IMR dashboard).
• Complete any other Individual Medical Readiness requirements not currently green.
• Schedule/complete Occupational Health exams, as applicable (AD only).
• Complete SHPE appointments (physical exam scheduled by SHPE nurse).
• BOMC signs Separation Memo and Virtual Out-Processing.
Steps to completing your SHPE at the VA:
• Schedule/complete appointment with VA representative. Must bring copy of medical record to appointment.
• Complete IMR requirements if not currently green.
• Schedule/complete Occupational Health exams, as applicable (AD only)
• Complete SHPE appointments with VA provider (scheduled by VA representative).
• VA Separation Health Assessment documentation returned to BOMC by VA.
• BOMC signs Separation Memo and vOP.
Important facts to remember:
• A SHPE is mandatory for all service members who meet eligibility criteria, and terminal leave can be affected if not accomplished.
• The DD Form 2807-1 (Report of Medical History) is ONLY in reference to service related diagnosis and/or conditions.
• National Guard and Reserve SMs should answer ‘yes’ on the DD Form 2807-1 only for conditions incurred or aggravated during current period of AD orders; not your entire military service.
• A termination audiogram only needs to be performed if you have not had one within 6 months of your date of separation (except ARC members).
• If you are planning to file a claim with the VA, it cannot be submitted more than 180 days before your date of separation.
• Your local VA representative contact information can be found on the back of this brochure.
• It is your responsibility to maintain communication with the BOMC office.
We propose TF-GridNet for speech separation. The model is a novel deep neural network (DNN) integrating full- and sub-band modeling in the time-frequency (T-F) domain. It stacks several blocks, each consisting of an intra-frame full-band module, a sub-band temporal module, and a cross-frame self-attention module. It is trained to perform complex spectral mapping, where the real and imaginary (RI) components of input signals are stacked as features to predict target RI components. We first evaluate it on monaural anechoic speaker separation. Without using data augmentation and dynamic mixing, it obtains a state-of-the-art 23.5 dB improvement in scale-invariant signal-to-distortion ratio (SI-SDR) on WSJ0-2mix, a standard dataset for two-speaker separation. To show its robustness to noise and reverberation, we evaluate it on monaural reverberant speaker separation using the SMS-WSJ dataset and on noisy-reverberant speaker separation using WHAMR!, and obtain state-of-the-art performance on both datasets. We then extend TF-GridNet to multi-microphone conditions through multi-microphone complex spectral mapping, and integrate it into a two-DNN system with a beamformer in between (named as MISO-BF-MISO in earlier studies), where the beamformer proposed in this article is a novel multi-frame Wiener filter computed based on the outputs of the first DNN. State-of-the-art performance is obtained on the multi-channel tasks of SMS-WSJ and WHAMR!. Besides speaker separation, we apply the proposed algorithms to speech dereverberation and noisy-reverberant speech enhancement. State-of-the-art performance is obtained on a dereverberation dataset and on the dataset of the recent L3DAS22 multi-channel speech enhancement challenge.
• Acoustic beamforming
• complex spectral mapping
• full- and sub-band integration
• speech separation
• Computer Science (miscellaneous)
• Acoustics and Ultrasonics
• Computational Mathematics
• Electrical and Electronic Engineering
T1 - TF-GridNet
T2 - Integrating Full- and Sub-Band Modeling for Speech Separation
AU - Wang, Zhong Qiu
AU - Cornell, Samuele
AU - Choi, Shukjae
AU - Lee, Younglo
AU - Kim, Byeong Yeol
AU - Watanabe, Shinji
N2 - We propose TF-GridNet for speech separation. The model is a novel deep neural network (DNN) integrating full- and sub-band modeling in the time-frequency (T-F) domain. It stacks several blocks, each consisting of an intra-frame full-band module, a sub-band temporal module, and a cross-frame self-attention module. It is trained to perform complex spectral mapping, where the real and imaginary (RI) components of input signals are stacked as features to predict target RI components. We first evaluate it on monaural anechoic speaker separation. Without using data augmentation and dynamic mixing, it obtains a state-of-the-art 23.5 dB improvement in scale-invariant signal-to-distortion ratio (SI-SDR) on WSJ0-2mix, a standard dataset for two-speaker separation. To show its robustness to noise and reverberation, we evaluate it on monaural reverberant speaker separation using the SMS-WSJ dataset and on noisy-reverberant speaker separation using WHAMR!, and obtain state-of-the-art performance on both datasets. We then extend TF-GridNet to multi-microphone conditions through multi-microphone complex spectral mapping, and integrate it into a two-DNN system with a beamformer in between (named as MISO-BF-MISO in earlier studies), where the beamformer proposed in this article is a novel multi-frame Wiener filter computed based on the outputs of the first DNN. State-of-the-art performance is obtained on the multi-channel tasks of SMS-WSJ and WHAMR!. Besides speaker separation, we apply the proposed algorithms to speech dereverberation and noisy-reverberant speech enhancement. State-of-the-art performance is obtained on a dereverberation dataset and on the dataset of the recent L3DAS22 multi-channel speech enhancement challenge.
AB - We propose TF-GridNet for speech separation. The model is a novel deep neural network (DNN) integrating full- and sub-band modeling in the time-frequency (T-F) domain. It stacks several blocks, each consisting of an intra-frame full-band module, a sub-band temporal module, and a cross-frame self-attention module. It is trained to perform complex spectral mapping, where the real and imaginary (RI) components of input signals are stacked as features to predict target RI components. We first evaluate it on monaural anechoic speaker separation. Without using data augmentation and dynamic mixing, it obtains a state-of-the-art 23.5 dB improvement in scale-invariant signal-to-distortion ratio (SI-SDR) on WSJ0-2mix, a standard dataset for two-speaker separation. To show its robustness to noise and reverberation, we evaluate it on monaural reverberant speaker separation using the SMS-WSJ dataset and on noisy-reverberant speaker separation using WHAMR!, and obtain state-of-the-art performance on both datasets. We then extend TF-GridNet to multi-microphone conditions through multi-microphone complex spectral mapping, and integrate it into a two-DNN system with a beamformer in between (named as MISO-BF-MISO in earlier studies), where the beamformer proposed in this article is a novel multi-frame Wiener filter computed based on the outputs of the first DNN. State-of-the-art performance is obtained on the multi-channel tasks of SMS-WSJ and WHAMR!. Besides speaker separation, we apply the proposed algorithms to speech dereverberation and noisy-reverberant speech enhancement. State-of-the-art performance is obtained on a dereverberation dataset and on the dataset of the recent L3DAS22 multi-channel speech enhancement challenge.
KW - Acoustic beamforming
KW - complex spectral mapping
KW - full- and sub-band integration
KW - speech separation
Good afternoon.
Now there is a full-mesh vpn network on CheckPoint, but the current main SMS is located in another country (let's call it A) and manages all Checkpoint gateways. Communication with SMS via MPLS and via the Internet.
The separation of a part of the gateways and their transfer to the control of another SMS (in another location, let's call it B) is being considered.
I have an idea.:
1) deploy Secondary SMS to location B and connect it to the current one located in another country A.
2) Synchronize everything.
3) Make Secondary SMS active in the location of the Bar.
4) then, in some way, break the connection with another SMS in country A, say, disable MPLS or restrict connection.
5) you will probably have to deploy another SMS in location B with the same name as the former main SMS in country A and upgrade it to Primary.
5) Reinitialize SIC on gateways that require SMS connection in country A and possibly reinitialize SIC on gateways that will be connected to SMS in location B.
But I'm not sure about the result and the possibilities.
Maybe someone has asked such a task? what is the best way to perform such a separation-transferring part of the gateways to the new SMS?
Abstract
Removal of oils and organic solvents from water is an important global challenge for energy conservation and environmental protection. Advanced sorbent materials with excellent sorption capacity need to be developed. Here we report on a superhydrophobic and superoleophilic MoS nanosheet sponge (SMS) for highly efficient separation and absorption of oils or organic solvents from water. This novel sponge exhibits excellent absorption performance through a combination of superhydrophobicity, high porosity, robust stability in harsh conditions (including flame retardance and inertness to corrosive and different temperature environments) and excellent mechanical properties. The dip-coating strategy proposed for the fabrication of the SMS, which does not require a complicated process or sophisticated equipment, is very straightforward and easy to scale up. This finding shows promise for water remediation and oil recovery.
Introduction
Oil spillage and the organic solvents discharged by chemical industries are primary pollutants of water resources, and have resulted in significant energy losses, serious environmental pollution and consequent ecological problems. Under such circumstances, superhydrophobic porous materials, such as sponges, meshes, fabrics, and membranes, have stimulated great interest because of their capacity for selective absorption/separation of oils or organic solvents while repelling water completely
Schematic illustration of the fabrication process for a superhydrophobic and superoleophilic MoS sponge for oil-water separation.
Optical microscopy illustrates that MoS nanosheets extracted from MoS crystals have a large individual planar structure with several micrometers in width (Fig. S1). Transmission electron microscopy (TEM) further reveals that the thickness of the sheets ranges from dozens of nanometers to several hundred nanometers, this originates from the restacking of single layer MoS sheets. Selected area electron diffraction analysis reveals hexagonal spots in selected regions of the large sheets (Fig. S2). The individual MoS nanosheets consist of a number of rough surfaces and folded edges, with a micro/nano-textured structure, which is fundamentally important to the wettability of a surface. To demonstrate the hydrophobic property of the MoS nanosheets, water contact angle (WCA) measurement was performed on the surface of MoS films which were deposited on an aluminum substrate using a dip-coating method. It was observed that the MoS films are strongly hydrophobic with a WCA of 122° ± 3° (Fig. S3).
Scanning electron microscopoy (SEM) was used to examine the morphological evolution of the sponge before and after the hydrophobic modification. As shown in Fig. 2, the sponge before and after coating with the MoS nanosheets display exactly the same porous structure, which is an inherent 3D interconnected porous structure with macro pores of hundreds of micrometers, thus confirming that the small modification does not damage the original structure of the sponge or block the pores inside it. These characteristics are beneficial for the rapid uptake of oil, as the open-pore network permits the rapid transport of gas and liquid in the sponge. It is clear that the smooth skeletons of the original sponge are covered with MoS nanosheets after dip-coating (Fig. 2b). A higher magnification SEM image of the MoS-coated sponge reveals hierarchical structures that exist in the form of crater-like protrusion, which are the stacked MoS nanosheets with micro/nano-scale folded edges. Like the surface structure of a lotus leaf, these hydrophobic MoS nanosheets in combination with the micro-porous structure of the sponge create a doubly roughened surface, which leads to a composite interface in which air has become trapped within the grooves beneath the liquid, therefore achieving superhydrophobicity (the so-called Cassie-Baxter model)
Figure 2
Wettability behavior
The raw MF sponge exhibits a typical superhydrophibic and superoleophilic behavior (Fig. S4). To control the different loadings of the MoS nanosheets on the superhydrophobic property of SMS in the repeated “dipping and drying” process, we defined the weight ratio WMoS2/Wsponge (Wsponge and WMoS2 are determined by initial weight and weight of MoS-coated sponge, which are weighed immediately after being taken out of the oven to avoid moisture absorption, respectively) as the loading index. Figure 3a shows the variation in the MoS loading index with its corresponding WCA values. It can be seen that the WCA increases rapidly when increasing the MoS loading at low concentrations. As the MoS loading index increases to 8.4% or greater, water droplets attained quasi-spherical shapes on the sponge surfaces with CAs of 150° ± 2°, indicating superhydrophobic behavior. These results suggest that an unsaturated coating degrades the superhydrophobicity of the coated sponges, while an oversaturated coating brings no further improvement in superhydrophobicity and may block the sponge pores. Thus superhydrophobic sponges with a 9.4% MoS loading were employed in the following study.
Figure 3
a) Effect of MoS nanosheet loading on the WCA of the pure sponge; (b) Photograph of SMS after being placed into water - the inset is a photograph of the SMS partially immersed in water by force; (c) Water droplets (in red) -as quasi-spheres and gasoline trace (marked by a circle) on the surface of the SMS - Inset: optical image of a water droplet on the prepared sponge; (d) Photograph of water droplets as quasi-spheres and gasoline trace on the surface of the MoS sponge after oil-saturated burning - Inset: optical image of a water droplet on the burned sponge.
As shown in Fig. 3b, a fabricated SMS (black color) floated on a water surface and no water uptake was found, while a pure MF sponge (white color) sank to the bottom of the beaker. When the SMS was immersed in water under an external force (inset of Fig. 3b), the surface of the superhydrophobic sponge appeared like that of a silver mirror, suggesting that this sponge features Cassie-Baxter surfaces. This is due to a composite interface in which a uniform air layer has become trapped between the water and sponge surfaces. Figure 3c shows the water droplets attained near-spherical shapes and rolled off with ease when placed on the surface of the SMS. The inset in Fig. 3c is an optical image of a water droplet (10 μl) on the surface of the SMS with a WCA of 151° ± 2°. By contrast, when gasoline was dropped onto the surface of the SMS, it was immediately absorbed by the sponge, as indicated by the circled area in Fig. 3c, demonstrating its superoleophilic property. The superhydrophobic and superoleophilic surfaces demonstrated here can be attributed to the combination of the micro-porous structure of the sponge, the hydrophobic chemical property of the MoS nanosheets, and the micro/nano-textured structure of the MoS nanosheets on the sponge skeletons.
To further evaluate chemical inertness, the hydrophobic stability of the SMS over different pH values and temperatures was tested. The SMS was immersed in aqueous solutions with a broad pH range (1–13) for 24 h and tested. As shown in Fig. 4a, the WCAs of the sponges immersed in aqueous solutions with different pH values are still greater than 145° ± 2°, suggesting that their strong hydrophobicity is resistant to corrosive environments. As shown in Fig. 4b, the WCAs of SMSs exposed to hot (220 °C) and cold (−16 °C) environments for 1 h are the same as in a room (25 °C) environment, which indicates that their wettability is also highly independent of temperature. These features show the superhydrophobic MoS sponge is highly stable and robust in various harsh environments, which may further extend its potential use.
Figure 4
a) Relationships between pH values and WCAs of the SMS after 24 h immersion in aqueous solutions with different pH values; (b) Photograph of water droplets on the surface of MoS sponge after exposure in room (left), hot (center), and cold (right) environments, respectively - inset: optical image of a water droplet on the exposed SMS.
Oil/organic solvents - water separation
Due to its high porosity, superhydrophobicity and robust stability, the SMS is an excellent candidate for the clean-up of oils and organic solvents in water. Here we chose two organic solvents with different densities, rapeseed oil and chloroform, as model absorbates to verify how SMS would respond as an effective absorbent for organic contaminants. As shown in Fig. 5a, once a piece of SMS was dropped into contact with a layer of the rapeseed oil (dyed with Sudan III) on a water surface, the SMS completely absorbed the oil, resulting in a transparent region of clean water which was originally contaminated by the oil (see detail in Movie S1).The process finished within a few seconds, suggesting a useful route for cleaning up oil spillages. Similarly, chloroform, which sinks to the bottom of water, was also rapidly sucked up by the SMS (Fig. 5b, see detail in Movie S2). Such fast absorption kinetics of the SMS is attributed to the combination of its high porosity, capillary action, and oleophilic nature.
Figure 5
Photographs of: the adsorption process of (a) rapeseed oil (dyed with Sudan III) and (b) chloroform; the adsorption process of water using MoS sponge; (c) the absorption capacities of the MoS sponge toward oils and organic solvents; (d) the absorption recyclability of the MoS sponge with different kinds of oils; (e) The absorption recyclability of the MoS sponge at different temperatures; (f ) continuous collection of gasoline in situ from a water surface with the apparatus.
As shown in Fig. 5c, the SMS exhibits excellent absorption capacities towards a wide range of oils (rapeseed oil, gasoline, and diesel oil) and organic solvents (Acetone, Ethanol, Methyl alcohol, Toluene, Hexane, Ethylene glycol, chloroform, Cyclohexane, 2-Propanol, and Butyl alcohol), and absorbs up to 82–159 times its own weight, depending on the density of the absorbates. In particular, the SMS shows an absorption capacity of 93 wt/wt for diesel oil and 159 wt/wt for chloroform, respectively. These absorption capacities are significantly higher than those of commercial PP fabrics and many previously reported high-performance absorbent, e.g. ~20 times for nanowire membranes, ~33 times for micro-porous polymers, and 15–25 times for the CNT/PDMS-coated PU sponge, and are comparable to those of ultralight carbon aerogels or sponges for similar oils and solvents. It should be noted that the fabrication process for our SMS is simple and easy to scale up.
To further test the recyclability of SMS for the clean-up of oil, we used typical oils (rapeseed oil, gasoline and diesel oil) as model absorbates to investigate the cyclic absorption/squeezing behavior of the sponge. After absorbing all the oil, the sponges could be squeezed out mechanically to harvest the absorbed oils. Figure 5d shows the recyclable use of the SMS for the absorption of different oils. It is evident that the recyclable absorption behavior of the SMS for three kinds of oils is analogous, i.e. a slight deterioration in absorbency was observed over 50 repetitions, indicating its good recyclability. This decrease is due to the residual oil inside the sponges which could not be removed by manual squeezing during each cycle. This recyclable absorption behavior is obviously stronger than those of previously reported sponges, e.g., the cycles of nanoparticle copper coated sponges is less than 20, which decreases rapidly with increasing cycle, the absorption capacities of the graphite-based sponge deteriorates rapidly after two cycles. Importantly, the water-repelling behavior of the sponges just decreased slightly after 20 cycles of the absorption/squeezing test, as evidenced by a high WCA of 145° ± 2° (Fig. S5). As a consequence of its high chemical inertness, the superhydrophobic sponge is still robust in high temperature environments (Fig. 5e), e.g. its oil absorption capacity after 30 cycles of the absorption/squeezing test in 80 °C is almost as same as in room temperature.
For practical and commercial applications, it is essential to develop a novel, continuous, and convenient collection method,. Here, we achieved continuous collection of oil in situ from a water surface based on a simple combination of SMS with pipes and a peristaltic pump. As demonstrated in Fig. 5f, only the pure oil was absorbed by the SMS and flowed along the pipes to the collecting cup, leaving the SMS continuously able to collect the oil (see detail in Movie S3). We also investigated the oil-collection performance of the pump on a water surface with simulated waves, the results show that the shaking of the SMS on the water surface did not affect the oil-separation efficiency because of its buoyancy (Fig. S6 and Movie S4). Moreover, the collection of diesel oil via this pumping apparatus can be maintained for more than 10 hrs without an obvious decrease in flux, indicating the long-time working stability of the SMS (Fig. S7 and Movie S5). This novel oil-collection technique makes the separation of oil-water emulsions easier and faster, which brings SMS a step closer to practical application in oil-water separation.
Flame-retardance and burning for regeneration
Most organic solvents and oils require separation are highly flammable when ignited, and so it is beneficial to further study the flame-retardant property of the SMS. Here, the combustion behavior of the SMS and MF sponge was investigated using burning tests. It is clear that the MF sponge utilized in this work has a flame-retardant property, and the sponge after superhydrophobic modification inherits this advantage (Figs S8a,b), which indicate sits potential for reducing the risk of fire and explosion. Gasoline was used as a model oil to investigate the combustion behavior of the oil-saturated SMS. The result shows that the gasoline absorbed by the SMS extinguishes less than 70 seconds after being ignited, leaving behind a half-burned sponge (see Fig. S8c). The total weight of the residue is 56% of the original weight, confirming the flame-retardant property of the SMS. More importantly, the SMS can be reused several times by directly burning it in air, as is done with other porous polymer and BN sorbents,. As shown in Fig. 3d, the residue from a burned SMS exhibits dark color, partial shrinkage in volume, and a slightly reduce water contact angle (143° ± 3° after the first cycle), which attributes to the presence of carbonaceous matter. Oil can be taken up again at least five times with a slight decrease in capacity (Fig. S9). This is in contrast to other carbon-based materials and polymer-based sorbents that have higher initial capacities, but cannot withstand such harsh conditions and therefore can only be used several times before their porosity is completely filled by carbonaceous matter.
Mechanical stability
Its excellent mechanical properties are also of great importance for SMS in order to realize its applications in oil-water separation. Here, compression experiments were performed to evaluate the mechanical performances of SMS. The prepared SMS completely recovers its original shape without plastic deformation after compression, and this is maintained without apparent structural damage even after 1000 cycles of a 50% compression test (Fig. S10), indicating excellent flexibility and mechanical robustness. Importantly, the SMS can be not only highly compressed but also bent and twisted, as shown in Fig. S11. After releasing the loading, it rapidly recovers its original shape without structural fatigue. These excellent mechanical properties of SMS are attributed to its unique structural design, which partly transfers a load from the MoS nanosheets to the polymer skeletons under mechanical deformation. Once the load is removed, the polymer skeletons return to their original configurations, allowing the SMS to recover its initial shape. Interestingly, the SMS still exhibits robust mechanical stability in burning conditions, e.g. after one cycle of burning it can be compressed easily, and completely recovers its original shape without mechanical failure (Fig. S12).
Materials and synthesis
In this study, MoS bulk crystals (0.2 g, 99%, Alfa Aesar) were added to 200 ml of ethanol in a 250 ml capacity, flat-bottomed beaker. These samples were sonicated continuously for 24 h using a horn probe sonic tip. They were then centrifuged at 1000 rpm for 15 min to obtain a MoS nanosheets dispersed in ethanol solution. A piece of commercial melamine-formaldehyde sponge was first cleaned with acetone and distilled water successively using an ultrasonic cleaner, followed by drying in a vacuum oven at 100 °C for several hours to completely remove all moisture. The dried sponge was cut into smaller size (2 × 2 × 4 cm) and was then dipped into a dispersion of MoS nanosheets in ethanol, and finally dried in a vacuum oven at 100 °C for 2 h. Different loadings of MoS nanosheets on the sponges were controlled by repeating the “dipping and drying” process.The density of the fabricated MoS-based sponges was about 0.0101 g/cm.
Material characterization
SEM images were collected in a JSM-6610LV scanning electron microscope. TEM images were produced in JEOL JEM-2010 transmission electron microscope. Water contact angles were measured using a Rame-hart Model 250 Goniometer at room temperature, and the volume of distilled water droplets was 10 μL. The compression tests were performed on an Instron universal testing machine with a compressive rate of 20 mm/min.
Additional Information
How to cite this article: Gao, X. et al. Flexible Superhydrophobic and Superoleophilic MoS Sponge for Highly Efficient Oil-Water Separation. Sci. Rep. , 27207; doi: 10.1038/srep27207 .
References
• Chu, Z., Feng, Y. & Seeger, S. Oil/water separation with selective superantiwetting/superwetting surface mterials. Angew. Chem. Int. Ed. , 2328–2338 .
• Wang, G. & Uyama, H. Facile synthesis of flexible macroporous polypropylene sponges for separation of oil and water. Sci. Rep. , 21265 .
• Wang, Z., Xu, Y., Liu, Y. & Shao, L. A novel mussel-inspired strategy toward superhydrophobic surfaces for self-driven crude oil spill cleanup. J. Mater. Chem A , 12171–12178 .
• Wang, Z., Jiang, X., Cheng, X., Lau, C. H. & Shao, L. Mussel-inspired hybrid coatings that transform membrane hydrophobicity into high hydrophilicity and underwater superoleophobicity for oil-in-water emulsion separation. Acs Appl. Mater. Inter. , 9534–9545 .
• Zhang, R. et al. Three-dimensional porous graphene sponges assembled with the combination of surfactant and freeze-drying. Nano Res. , 1477–1487 .
• Duan, B., Gao, H., He, M. & Zhang, L. Hydrophobic modification on surface of chitin sponges for highly effective separation of oil. Acs Appl. Mater. Inter. , 19933–19942 .
• Wu, C., Huang, X., Wu, X., Qian, R. & Jiang, P. Mechanically flexible and multifunctional polymer-based graphene foams for elastic conductors and oil-water separators. Adv. Mater. , 5 .
• Nguyen, D. D., Tai, N. H., Lee, S. B. & Kuo, W. S. Superhydrophobic and superoleophilic properties of graphene-based sponges fabricated using a facile dip coating method. Energ. Environ. Sci. , 7908–7912 .
• Ganatra, R. & Zhang, Q. Few-layer MoS2: a promising layered semiconductor. ACS Nano , 4074–4099 .
• Butler, S. Z. et al. Progress, challenges, and opportunities in two-dimensional materials beyond graphene. ACS Nano , 2898–2926 .
• Rao, C. N. R., Gopalakrishnan, K. & Maitra, U. Comparative study of potential applications of graphene, MoS2, and other two-dimensional materials in energy devices, sensors, and related areas. Acs Appl. Mater. Inter. , 7809–7832 .
• Akinwande, D., Petrone, N. & Hone, J. Two-dimensional flexible nanoelectronics. Nat. Commun. , 5678 .
• Zhu, W. et al. Electronic transport and device prospects of monolayer molybdenum disulphide grown by chemical vapour deposition. Nat. Commun. , 3087 .
• Yan, Y. et al. Vertically oriented MoS2 and WS2 nanosheets directly grown on carbon cloth as efficient and stable 3-dimensional hydrogen-evolving cathodes. J. Mater. Chem. A3, 131–135 .
• Yan, Y., Xia, B., Xu, Z. & Wang, X. Recent development of molybdenum sulfides as advanced electrocatalysts for hydrogen evolution reaction. ACS Catalysis , 1693–1705 .
• Jariwala, D., Sangwan, V. K., Lauhon, L. J., Marks, T. J. & Hersam, M. C. Emerging device applications for MoS2 iconducting two-dimensional transition metal dichalcogenides. ACS Nano , 1102–1120 .
• Chow, P. K. et al. Wetting of mono and few-layered WS2 and MoS2 films supported on Si/SiO2 substrates. ACS Nano , 3023–3031 .
• Kozbial, A., Gong, X., Liu, H. & Li, L. Understanding the intrinsic water wettability of molybdenum disulfide (MoS2). Langmuir , 8429–8435.
• Rafiee, J., Rafiee, M. A., Yu, Z. Z. & Koratkar, N. Superhydrophobic to superhydrophilic wetting control in graphene films. Adva. Mater. , 2151–2154 .
• Bertolazzi, S., Brivio, J. & Kis, A. Stretching and Breaking of Ultrathin MoS2, ACS Nano , 9703–9709 .
• Tian, Y., Su, B. & Jiang, L. Interfacial material system exhibiting superwettability. Adv. Mater. , 6872–6897 .
• Wang, C. F. & Lin, S. J. Robust superhydrophobic/superoleophilic sponge for effective continuous absorption and expulsion of oil pollutants from water. ACS Appl. Mater. Inter. , 8861–8864 .
• Hayase, G., Kanamori, K., Fukuchi, M., Kaji, H. & Nakanishi, K. Facile synthesis of marshmallow-like macroporous gels usable under harsh conditions for the separation of oil and water. Angew. Chem. Int. Ed. , 2040–2043 .
• Ruan, C., Ai, K., Li, X. & Lu, L. A superhydrophobic sponge with excellent absorbency and flame retardancy. Angew. Chem. Int. Ed. , 5556–5560 .
• Si, Y. et al. Superelastic and superhydrophobic nanofiber-assembled cellular aerogels for effective separation of oil/water emulsions. ACS Nano , 3791–3799 .
• Zhu, Q., Pan, Q. & Liu, F. Facile removal and collection of oils from water surfaces through superhydrophobic and superoleophilic sponges, J. Phys. Chem. C , 17464–17470 .
• Ge, J. et al. Pumping through porous hydrophobic/oleophilic materials: an alternative technology for oil spill remediation. Angew. Chem. Int. Ed. , 36120–3616 .
• Song, Y. et al. Ultralight boron nitride aerogels via template-assisted chemical vapor deposition. Sci. Rep. , 10337 .
Acknowledgements
• School of Materials Science and Engineering, Xiangtan University, Hunan 411105, China
Xiaojia Gao, Xiufeng Wang & Xiaoping Ouyang
• School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Bundoora, Victoria 3083, Australia ,
Cuie Wen
• Xiaojia Gao
• Xiufeng Wang
• Xiaoping Ouyang
• Cuie Wen
Contributions
X.W. and X.G. conceived and designed the experiments. X.G. performed the experiments. X.O., X.W. and C.W. provided technical guidance. X.W. and C.W. analyzed the experiments. X.W. and C.W. wrote the manuscript.
Cite this article
Gao, X., Wang, X., Ouyang, X. et al. Flexible Superhydrophobic and Superoleophilic MoS Sponge for Highly Efficient Oil-Water Separation. Sci Rep
Copy to clipboardThis article is cited by
• Hedyeh Rahmani
• Samira Mansouri Majd
• Abdollah Salimi
Ionics
• Ruiqian Zhang
• Ling Liu
• Qinghan Meng
Journal of Materials Science
• Edward Mohamed Hadji
• Bo Fu
• Jingtao Wang
Frontiers of Chemical Science and Engineering
• Lei Zhou
• Chenxi Fu
• Yian Zheng
Cellulose
• Hao Wu
• Yanli Liu
• Yating Shi
Food Analytical Methods
Смс разлука
Родной, разлука с тобой мне даётся непросто, я постоянно думаю о тебе, хочу прижаться к твоему крепкому плечу, поцеловать твои нежные губы. С нетерпением жду встречи, любимый мой муж.
Мой дорогой муж, разлука тяжела, но наше сердечное единство преодолеет расстояние. Твоя любовь — моя опора. С нетерпением жду тот миг, когда снова будем в объятиях друг друга. Люблю тебя сильнее с каждым днем.
Муж, ну как ты далеко!
В голове моей одно,
Что моей душе не сладко
И слезинкою украдкой
Мне она сказала, что
Без тебя ей тяжело...
Ненаглядный, милый муж,
Возвращайся скорей, уж!
Муж, в разлуке плохо мне!
Вижу лишь тебя во сне.
Одиноко и тоскливо
Стало в мире. Где ты, милый?
Поскорее возвращайся,
Нежно, мило улыбайся
Мне, любимый, рядом будь!
Потерплю еще чуть-чуть...
Дорогой любимый муж,
Уже долго очень, уж,
Мы не видимся с тобой...
Дорогой, когда домой?
Без тебя мне одиноко
И в разлуке очень плохо!
И надеюсь, что меня
Ты поймешь, любовь моя!
Муж, зачем эта разлука?!
Я соскучилась уже...
Для меня она как мука,
Грустно очень на душе!
Если сможешь поскорее
Возвращайся вновь ко мне,
Я печаль свою не скрою,
Очень хочется к тебе!
Муж, в разлуке мне с тобой
Очень плохо, дорогой!
Так и хочется сказать,
Что не нужно уезжать.
Нужно быть со мною рядом,
Счастья большего не надо
Для меня, любимый мой!
Жду тебя скорей домой!
Вот в разлуке мы с тобой,
Муж любимый, дорогой.
По тебе буду скучать
И в мечтах лишь обнимать.
Жду, что скоро дверь открою,
Стол тогда тебе накрою,
Нежно в губы поцелую.
Знай, что я уже тоскую.
Муж, не сладко будет мне
Без тебя... И я уже
Так скучаю, милый мой!
И хочу, чтоб ты домой
Поскорее вновь вернулся
И души моей коснулся
Взглядом, жестом, поцелуем.
Очень, ведь, тебя люблю я!
Муж, уже скучаю очень!
Не хватает дни и ночи
Мне тебя, ты мой родной,
Мой желанный, дорогой!
Но тебя дождусь, я знаю,
Снова солнце засияет,
Станет сладко на душе,
Когда вновь придешь ко мне!