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

Abstract

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.

The Influence of Self-Heating Iron on the Thermal, Mechanical, and Swelling Properties of PDMS Composites for Organic Solvents Removal

“…Volatile organic compounds exert a negative impact on the environment and human health. These compounds evaporate at room temperature and pressure, causing the vapors to be present in both indoor and outdoor environments [ 3 , 4 , 5 ]. The hazards caused by the increasing amounts of petrochemical solvents, such as toluene, chloroform, pentane, petroleum ether, and n-butanol, should be particularly focused on, as these solvents are highly toxic and difficult to remove from the environment [ 6 , 7 ].…”

“…Therefore, silicones are considered suitable polymeric matrices for various inorganic powders [ 1 , 2 , 3 ]. Polydimethylsiloxane (PDMS) is a biocompatible, inexpensive, and convenient-to-use elastomer comprising an inorganic siloxane (Si-O) backbone and organic methyl groups attached to the constituent silicon atoms [ 4 , 5 , 6 ]. The perfect PDMS system includes silanol-terminated PDMS, a crosslinker, and a catalyst as the major components, while reinforcing fillers and other additives may be added according to the application.…”

“…However, serious sedimentation and agglomeration problems due to the large density mismatch between the CI particle and medium oil have limited its engineering applications [ 10 ]. Drainage of organic compounds to surface waters threatens the aquatic environment with effects such as acute and chronic toxicity in the aquatic organisms, accumulation of pollutants in the marine ecosystem, and loss of habitats and biodiversity of marine life [ 3 , 4 , 5 ]. Petroleum hydrocarbon compounds, including toluene, chloroform, pentane, petroleum ether, and n-butanol, are often drained into the surface and underground waters due to industrial activities, particularly the mishandling of petrochemicals, reservoir leakages, and inappropriate waste disposal practices [ 6 , 7 , 8 ].…”

“…PDMS is highly soluble in non-polar solvents and, therefore, to render it chemically stable, the crosslinking of PDMS is necessary. PDMS sponge/carbon nanotubes are more comprehensive than the pure PDMS for efficient removal of oil from immiscible oil–water mixtures [ 4 ]. PDMS/graphene aerogels displayed a high adsorption capacity toward various organic solvents in the range of 48–96 g/g [ 5 ].…”

Polypropylene/Lignin/POSS Nanocomposites: Thermal and Wettability Properties, Application in Water Remediation

“…Industrial wastewater and oil spillage are considered as the main source of water pollution, which threatens human life and the marine system [ 1 , 2 , 3 , 4 , 5 ]. Moreover, water pollution creates a great loss of energy resources if not properly treated [ 6 ].…”