Corrosion-Resistant Hydrophobic MFI-Type Zeolite-Coated Mesh for Continuous Oil–Water Separation

Abstract

Efficient separation of oil–water mixtures has become a critical challenge due to frequent oil-spill accidents and enormous release of oil-containing wastewater by households or catering services. Superhydrophobic coatings on metal meshes have been evidenced as the effective and energy-saving materials for oil–water separation. However, it is difficult to fabricate the separating coatings with long-term superhydrophobicity and the outstanding anticorrosion properties for practical application. In this study, we fabricated the hydrophobic Mobil five (MFI)-type zeolite coatings on the pristine stainless steel meshes via an in situ crystallization method and subsequently modified them with an environmentally safe hexadecyltrimethoxysilane compound. The as-prepared coating meshes showed good self-cleaning, antifouling, and anticorrosion properties. Furthermore, the coated meshes were capable of continuously and efficiently separating different kinds of oil–water mixtures under gravity-driven pressure and had more than 99.0% high separation efficiency. More important, the prepared hydrophobic MFI-coated meshes had equivalent separation performance compared to that of superhydrophobic coating meshes. Meanwhile, the hydrophobic MFI-coated meshes demonstrated excellent reusability performance and long-term stability. These as-prepared meshes thus have great potential for applications in separating oily wastewater from oil fields as well as recycling of waste oil from catering services.

A Review on Oil/Water Mixture Separation Material

“…As a result, tremendous attention has been paid on the development of the superhydrophilic and underwater superhydrophobic metal mesh, which is also called a water-removing-type separation material via introducing a third repulsive water phase. 113,114 The mesh can adsorb or filter water from oil selectively just driven by gravity and is immune to oil fouling. 115,116 However, this type of mesh is sensitive to acid, alkaline, or salt solution in general, it is thus only applicable under mild conditions.…”

“…However, an oil-removing-type material is easily fouled or even suffers from being blocked up because of the intrinsic oleophilicity. , Besides, it is not suitable for oil/water separation driven by gravity because the density of water is higher than that of oil. As a result, tremendous attention has been paid on the development of the superhydrophilic and underwater superhydrophobic metal mesh, which is also called a water-removing-type separation material via introducing a third repulsive water phase. , The mesh can adsorb or filter water from oil selectively just driven by gravity and is immune to oil fouling. , However, this type of mesh is sensitive to acid, alkaline, or salt solution in general, it is thus only applicable under mild conditions …”

Suppressing the Competitive Effect of Water Vapor on CO Adsorption over 5A Molecular Sieves via Silanization Hydrophobic Modification

“…At present, the hydrophobic modification methods reported mainly include silanization reaction, − esterification reaction, improvement of the ratio of silicon to aluminum, , the use of hydrophobic template agents, , and so on. Among them, silanization technology has been increasingly employed in molecular sieve modification. , Sun et al − tailored the microenvironment of materials to stabilize Cu + against oxidation by coating polydimethylsiloxane (PDMS) and coordinating octadecylphosphonic acid (OPA) onto metal nodes, and the hydrophobicity of the materials was obviously improved.…”

A Study on the Corrosion Resistance of Hydrophobic Coatings on 65Mn Steel

“…Usually, two steps are involved: creating a rough micro/nanostructure and modifying the surface with a low surface energy material. Many techniques have been used to create micro/nanostructures, including in situ crystallization method [22], etching [23] and electrodeposition [20,24,25]. Fluorosilanes or long fatty acids are usually employed as low surface energy materials to fabricate hydrophobic coatings [23].…”

“…However, most of these techniques and materials are complicated, expensive or toxic. Cai et al [22] developed the hydrophobic Mobil five-type zeolite coatings on stainless steel via an in situ crystallization method and subsequently modifying them with hexadecyltrimethoxysilane. These coatings exhibited good self-cleaning, antifouling and anticorrosion properties.…”