scholarly journals Carbon Nanotubes and Polydopamine Modified Poly(dimethylsiloxane) Sponges for Efficient Oil–Water Separation

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2431
Author(s):  
Wen Zhang ◽  
Juanjuan Wang ◽  
Xue Han ◽  
Lele Li ◽  
Enping Liu ◽  
...  

In this paper, effective separation of oil from both immiscible oil–water mixtures and oil-in-water (O/W) emulsions are achieved by using poly(dimethylsiloxane)-based (PDMS-based) composite sponges. A modified hard template method using citric acid monohydrate as the hard template and dissolving it in ethanol is proposed to prepare PDMS sponge composited with carbon nanotubes (CNTs) both in the matrix and the surface. The introduction of CNTs endows the composite sponge with enhanced comprehensive properties including hydrophobicity, absorption capacity, and mechanical strength than the pure PDMS. We demonstrate the successful application of CNT-PDMS composite in efficient removal of oil from immiscible oil–water mixtures within not only a bath absorption, but also continuous separation for both static and turbulent flow conditions. This notable characteristic of the CNT-PDMS sponge enables it as a potential candidate for large-scale industrial oil–water separation. Furthermore, a polydopamine (PDA) modified CNT-PDMS is developed here, which firstly realizes the separation of O/W emulsion without continuous squeezing of the sponge. The combined superhydrophilic and superoleophilic property of PDA/CNT-PDMS is assumed to be critical in the spontaneously demulsification process.

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Peng Hong ◽  
Zhu Liu ◽  
Yang Gao ◽  
Yubin Chen ◽  
Mingxun Zhuang ◽  
...  

Superhydrophobic sponge as potential absorbing material for oil/water separation is attracting great attention recently. However, there are still some challenges to feasibly fabricate superhydrophobic sponge with large scale and low cost. Herein, a novel photochromic superhydrophobic melamine sponge (PDMS-SP sponge) is fabricated by facilely dip-coating and thermocuring of hydroxyl-terminated polydimethylsiloxanes mixed with photochromic spiropyran. FT-IR, EDS, and XPS results confirm the successful coating of PDMS-SP upon melamine sponge. The resultant sponge not only possesses excellent water repellency with a contact angle of 154.5° and oil-water separation efficiency with an oil absorption capacity of 48–116 folds of itself weight, but also shows photochromic phenomenon between colorless and purple when it is successively exposed to UV irradiation and visible light.


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3344
Author(s):  
De Liu ◽  
Shiying Wang ◽  
Tao Wu ◽  
Yujiang Li

The influence of different coupling agents and coupling times on the wettability of a polyurethane (PU) sponge surface were optimized. Octadecyltrichlorosilane (OTS) was selected as the optimal coupling agent to prepare the superhydrophobic sponge. The superhydrophobic sponge was prepared in one step, which has the advantages of simple operation and enhanced durability. The superhydrophobic sponge was characterized by scanning electron microscopy, Teclis Tracker tensiometry, and Fourier transform infrared (FT-IR) spectrophotometry. The water contact angle increased from 64.1° to 151.3°, exhibiting ideal superhydrophobicity. Oils and organic solvents with different viscosities and densities can be rapidly and selectively absorbed by superhydrophobic sponges, with an absorption capacity of 14.99 to 86.53 times the weight of the sponge itself, without absorbing any water. Since temperature affects the viscosity and ionic strength of oil, and influences the surface wettability of the sponges, the effect of temperature and ionic strength on the oil absorption capacity of the superhydrophobic sponges was measured, and its mechanism was elucidated. The results showed that the absorptive capacity retained more than 90% of the initial absorptive capacity after repeated use for 10 times. Low-cost, durable superhydrophobic sponges show great potential for large-scale oil-water separation.


Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1593 ◽  
Author(s):  
Hajo Yagoub ◽  
Liping Zhu ◽  
Mahmoud H. M. A. Shibraen ◽  
Ali A. Altam ◽  
Dafaalla M. D. Babiker ◽  
...  

The complex aerogel generated from nano-polysaccharides, chitin nanocrystals (ChiNC) and TEMPO-oxidized cellulose nanofibers (TCNF), and its derivative cationic guar gum (CGG) is successfully prepared via a facile freeze-drying method with glutaraldehyde (GA) as cross-linkers. The complexation of ChiNC, TCNF, and CGG is shown to be helpful in creating a porous structure in the three-dimensional aerogel, which creates within the aerogel with large pore volume and excellent compressive properties. The ChiNC/TCNF/CGG aerogel is then modified with methyltrichlorosilane (MTCS) to obtain superhydrophobicity/superoleophilicity and used for oil–water separation. The successful modification is demonstrated through FTIR, XPS, and surface wettability studies. A water contact angle of 155° on the aerogel surface and 150° on the surface of the inside part of aerogel are obtained for the MTCS-modified ChiNC/TCNF/CGG aerogel, resulting in its effective absorption of corn oil and organic solvents (toluene, n-hexane, and trichloromethane) from both beneath and at the surface of water with excellent absorption capacity (i.e., 21.9 g/g for trichloromethane). More importantly, the modified aerogel can be used to continuously separate oil from water with the assistance of a vacuum setup and maintains a high absorption capacity after being used for 10 cycles. The as-prepared superhydrophobic/superoleophilic ChiNC/TCNF/CGG aerogel can be used as a promising absorbent material for the removal of oil from aqueous media.


NANO ◽  
2021 ◽  
pp. 2150061
Author(s):  
Yuntian Wan ◽  
Xue Lin ◽  
Zhongshuai Chang ◽  
Xiaohui Dai ◽  
Jiangdong Dai

Currently, with the increasingly serious pollution problem of oily wastewater, it is urgent to develop advanced materials and methods. In this work, a Fe(III)-CMC@Ni(OH)2@Ni composite foam with superhydrophilic and underwater superoleophobicity was fabricated by an in situ growth of flower-like Ni(OH)2 nanoparticles and chelated assembly of Fe(III)-CMC nanohydrogel via a layer-by-layer self assembly using Fe[Formula: see text] ion and carboxymethyl cellulose (CMC). The composite foam could separate various oil/water mixtures and exhibited excellent efficiency over 99%. This foam possessed ultrahigh water flux (220000[Formula: see text]L m[Formula: see text] h[Formula: see text] and better resistant to penetration pressure (1.3[Formula: see text]kPa). After 30 cycles, the oil–water separation performance reduced only 0.5%, but the foam structure was still stable that guarantees a better lifetime. Besides, this composite foam showed anti-fouling, unique durability and excellent corrosion resistance performance. Taking into account all good properties, Fe(III)-CMC@Ni(OH)2@Ni composite foam was expected to be a potential candidate for responding to all kinds of complex oily wastewater conditions.


2020 ◽  
Vol 8 ◽  
Author(s):  
Usama Zulfiqar ◽  
Andrew G. Thomas ◽  
Allan Matthews ◽  
David J. Lewis

Oil/water mixtures are a potentially major source of environmental pollution if efficient separation technology is not employed during processing. A large volume of oil/water mixtures is produced via many manufacturing operations in food, petrochemical, mining, and metal industries and can be exposed to water sources on a regular basis. To date, several techniques are used in practice to deal with industrial oil/water mixtures and oil spills such as in situ burning of oil, bioremediation, and solidifiers, which change the physical shape of oil as a result of chemical interaction. Physical separation of oil/water mixtures is in industrial practice; however, the existing technologies to do so often require either dissipation of large amounts of energy (such as in cyclones and hydrocyclones) or large residence times or inventories of fluids (such as in decanters). Recently, materials with selective wettability have gained attention for application in separation of oil/water mixtures and surfactant stabilized emulsions. For example, a superhydrophobic material is selectively wettable toward oil while having a poor affinity for the aqueous phase; therefore, a superhydrophobic porous material can easily adsorb the oil while completely rejecting the water from an oil/water mixture, thus physically separating the two components. The ease of separation, low cost, and low-energy requirements are some of the other advantages offered by these materials over existing practices of oil/water separation. The present review aims to focus on the surface engineering aspects to achieve selectively wettability in materials and its their relationship with the separation of oil/water mixtures with particular focus on emulsions, on factors contributing to their stability, and on how wettability can be helpful in their separation. Finally, the challenges in application of superwettable materials will be highlighted, and potential solutions to improve the application of these materials will be put forward.


2020 ◽  
Vol 32 (10) ◽  
pp. 1094-1101
Author(s):  
Yongpeng Wang ◽  
Pengtao Yan ◽  
Xintong Huo ◽  
Mengzhu Liu ◽  
Haibo Zhang ◽  
...  

Novel super-hydrophobic poly(aryl ether ketone) (PAEK) membranes have been firstly prepared by modifying ordinary PAEK into hexafluorbisphenol A-PAEK through traditional nucleophilic condensation polymerization and subsequently simple electrospraying technique. With the solution concentration increased, the micromorphology exhibited nanofibers, nanofiber with spindles, 3D network with microspheres embedded, microspheres and dense films, successively. The static water contact angle increased from 99° to 155°, while the sliding angle from 1.3° to 6.8° (±1°), in which the 3D network presented the strongest super-hydrophobicity. After 200 h of water flushing, the rough surface structure and super-hydrophobicity of the membranes were well retained. Moreover, the membrane exhibited wonderful self-cleaning property, oil/water separation property, and stability due to the hierarchical micro/nanostructures. This work provides a new route for the creation of super-hydrophobic high performance engineering plastic fabrics with the potential values in large-scale application of filtration, oil/water separation, and antifouling.


2019 ◽  
Vol 6 (2) ◽  
pp. 181823 ◽  
Author(s):  
Guangyu Shi ◽  
Yizhu Qian ◽  
Fengzhi Tan ◽  
Weijie Cai ◽  
Yuan Li ◽  
...  

Oil/water separation is a field of high significance as it might efficiently resolve the contamination of industrial oily wastewater and other oil/water pollution. In this paper, an environmentally-friendly hydrophobic aerogel with high porosity and low density was successfully synthesized with renewable pomelo peels (PPs) as precursors. Typically, a series of sponge aerogels (HPSA-0, HPSA-1 and HPSA-2) were facilely prepared via high-speed dispersion, freeze-drying and silanization with methyltrimethoxysilane. Indeed, the physical properties of aerogel such as density and pore diameter could be tailored by different additives (filter paper fibre and polyvinyl alcohol). Hence, their physico-chemical properties including internal morphology and chemical structure were characterized in detail by Fourier transform infrared, Brunauer–Emmett–Teller, X-ray diffraction, scanning electron microscope, Thermal gravimetric analyzer (TG) etc. Moreover, the adsorption capacity was further determined and the results revealed that the PP-based aerogels presented excellent adsorption performance for a wide range of oil products and/or organic solvents (crude oil 49.8 g g −1 , soya bean oil 62.3 g g −1 , chloroform 71.3 g g −1 etc.). The corresponding cyclic tests showed the absorption capacity decreased slightly from 94.66% to 93.82% after 10 consecutive cycles, indicating a high recyclability.


Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1629
Author(s):  
Xuecheng Yu ◽  
Ying Xiong ◽  
Zhen Li ◽  
Hongding Tang

Three series of silicone modified polyurethane acrylate (SPUA) prepolymers were prepared from dicyclohexylmethane-4, 4′-diisocyanate (HMDI), PPG1000, triethylene glycol (TEG), 2-hydroxyethyl acrylate (HEA), and multi-hydroxyalkyl silicone (MI-III) with tris(trimethylsiloxy)silyl propyl side groups. Their structures were confirmed by 1H NMR, 13C NMR, and Fourier transformed infrared (FTIR) analysis, and SPUA films were obtained by UV curing. The properties of films were investigated by attenuated total reflection (ATR)-FTIR, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), water contact angle (WCA), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), water and hexane resistance, and tensile testing. The results showed that the structures and dosages of MI-III could influence the polymerization properties, surface properties, water and n-hexane resistance, and thermal and tensile properties of SPUA. For instance, the surface aggregation of tris(trimethylsiloxy)silyl propyl groups (even ~2.5 wt%) could endow SPUA films with less microphase separation, good hydrophobicity, lipophilicity, thermal stability, and mechanical properties. Interestingly, obvious regular winkles appeared on the surfaces of SPUAIII films, which are characterized by relatively high WCA values. However, relatively smooth were observed on the surfaces of SPUAIII films, which also exhibit lower water absorption ratio values. Furthermore, the ordinary cotton textiles would be transformed into hydrophobic and oleophilic textiles after treating with SPUA simply, and they were used in the oil/water separation study. Among them, consistent with water and hexane resistance analysis of SPUA films, SPUAII treated cotton textiles are characterized by relatively small liquid absorption capacity (LAC) values. Thus, phenyl groups and side-chain tris(trimethylsiloxy)silyl propyl groups are helpful to improve the hydrophobicity and lipophilicity of SPUA films. SPUAII-5 (even with 5 wt% MII) treated cotton textiles could efficiently separate the oil/water mixture, such as n-hexane, cyclohexane, or methylbenzene with water. Thus, this material has great potential in the application of hydrophobic treatment, oil/water separation, and industrial sewage emissions, among others.


1975 ◽  
Vol 1975 (1) ◽  
pp. 195-200
Author(s):  
Robert J. Fiocco ◽  
Vincent W. Ridley

ABSTRACT Slop tanks are the focal point of the Load-On-Top system used on crude oil tankers to prevent pollution of the sea. Design of these tanks and their operating procedures strongly affect the degree of oil-water separation achieved. This paper presents the results of an investigation undertaken to define designs and procedures for improving separation and minimizing oil discharge to sea. The program was funded in part by the U.S. Maritime Administration. Based on tanker experience and laboratory tests with tank models, guidelines on capacity, structure, inlets, outlets, system design, and wastewater handling, procedures were developed. The guidelines aim at assuring successful Load-On-Top operations by (1) providing tanker operational flexibility for handling oily water, (2) minimizing the degree of oil-water mixing, (3) avoiding re-dispersion of separated oil during feeding and discharging operations, and (4) eliminating the possibility of accidental oil contamination. This investigation provides a basis for future large-scale or shipboard studies to improve the performance of slop tanks on existing tankers as well as on future tankers.


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