Ceramic Pore Channels with Inducted Carbon Nanotubes for Removing Oil from Water

Abstract

Water contaminated with tiny oil emulsions is costly and difficult to treat because of the colloidal stability and deformable nature of emulsified oil. This work utilizes carbon nanotubes (CNTs) in macro/mesopore channels of ceramic membrane to remove tiny oil droplets from water. The CNTs were implanted into the porous ceramic channels by means of chemical vapor deposition. Being hydrophobic in nature and possessing an interfacial curvature at nanoscale, CNTs enabled tiny oil emulsion in submicrometer and nano scales to be entrapped while permeating through the CNTs implanted pore channels. Optimizing the growth condition of the CNTs resulted in a uniform distribution of CNT grids, which allowed the development of lipophilic layers during filtration. These lipo-layers drastically enhanced the separation performance. The filtration capability of CNT-ceramic membrane was assessed by the purification of a dilute oil-in-water (o/w) emulsion containing ca. 210 ppm mineral oil 1600 ppm emulsifier, and a trace amount of dye, a proxy polluted water source. The best CNT-tailored ceramic membrane, prepared under the optimized CNT growth condition, claimed 100% oil rejection rate and a permeation flux of 0.6 L m(-2) min(-1), driven by a pressure drop of ca. 1 bar for 3 days on the basis of UV measurement. The CNT-sustained adsorption complements the size-exclusion mechanism in removing soluble oil.

A low-cost mullite-titania composite ceramic hollow fiber microfiltration membrane for highly efficient separation of oil-in-water emulsion

“…In general, hydrophobic membranes have a greater tendency to be fouled than hydrophilic membranes, the hydrophobic membrane (Marchese et al, 2000;Chen et al, 2012;Salahi et al, 2010;Ahmad et al, 2011;Abadi et al, 2011;Wandera et al, 2011;Li et al, 2006), as expected, had very low water permeation flux as indicated in Table 1. This is usually attributed to the fact that organic compounds, usually being hydrophobic, are more favorable to be adsorbed on the hydrophobic membrane surface than stay in water.…”

Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs)-Based Composite Membranes: A Review

“…Among various substrates, porous ceramic membranes in different geometries have been widely used to allow CNTs growth due to their excellent chemical, mechanical and thermal stability. Additionally, alumina (Al 2 O 3 ), yttria stabilized zirconia (YSZ), and mullite are the most commonly studied membrane materials [47,51,52,53,54,55,56,57]. Interestingly, randomly arranged or vertically aligned CNTs could be fabricated by different CVD conditions.…”

“…Fundamentally, due to the hydrophobicity and adequate adsorption sites for oil molecules in water of CNTs, assimilation of adsorption into size exclusion separation membrane has been proposed as an effective way to treat oil-in-water emulsion. Chen et al fabricated a new CNTs-based composite membrane by implanting CNTs in pore channels of an Y 2 O 3 -ZrO 2 (YSZ) membrane via CVD [56]. The YSZ membranes with CNTs showed 100% rejection rate of oil particles and maintained a permeate flux of 0.6 L·m −2 ·min −1 at 1 bar pressure drop over 3 days of operation.…”

Microfluidic fabrication of magnetic porous multi-walled carbon nanotube beads for oil and organic solvent adsorption

“…[14][15][16] Until now, many efforts have been devoted to developing carbon nanotube-based adsorbents and aimed at removing pollutants from water. [17][18][19][20][21][22] However, the carbon nanotube-based materials, as well as most of the other oil adsorbents, have a low density and hydrophobic surface.…”