Abstract
Surface hydrophobic modification for oil–water separation based on membrane filtration is essential but still challenging in dealing with various industrial and environmental problems like sewage treatment and oil spill. Chemical graft technology can arm membranes with more efficient durability for applications due to the stronger chemical interaction between modified layers and surfaces compared with physical coating technology. As cellulose-based material, cotton filter fabric is a flexible and degradable material with abundant hydroxyl groups, providing great possibility for graft reactions. Stearyol chloride has both hydrophobic alkyl chain and active acyl group, making it easily to be grafted onto cotton filter fabrics. Therefore, we propose to use stearoyl chloride as hydrophobic layer and one-step modify cotton filter fabric after activation. The obtained hydrophobic modified cotton filter fabric exhibits high contact angles (CAmax = 147o, CAavg = 141.8o), which only decrease slightly after 5 h droplet holding time (CAmax = 141o, CAavg = 126.3o). Besides, experiments also confirm that this modified membrane displays excellent anti-fouling property against different drinks as well as anti-washing property for 10 cycles. Much more surprised is that the obtained membrane displays outstanding anti-abrasion performance that the CA values can remain above 131o after 390 cycles abrasion with hektogram counterweight. As for filtration application, the modified membrane also shows hydrophobic durability after three times gravity-driven oil–water separation (CAmax = 137o, CAavg = 132.6o). This hydrophobic modified cotton filter fabric may have potential application in future oilwater separation and the stearoyl chloride graft technology is an both effective and efficient way in surface hydrophobic modification.
Highlights
Oil-water separation is an inevitable process in many industries to protect environment and ecology
Our group used to graft alkyl chains on flexible cotton filter fabrics via activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP)[Li et al 2019]
In order to figure out this problem, we launched CS2/NaOH pretreatment to activate -OH on the cotton filter fabric before ARGET-ATRP process and successfully improved the hydrophobic durability that the droplet can be held for 150 min[Luo et al 2020]
Summary
Oil-water separation is an inevitable process in many industries to protect environment and ecology. Our group used to graft alkyl chains on flexible cotton filter fabrics via activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP)[Li et al 2019]. The obtained hydrophobic modified fabric exhibits high CA value of 145o, its durability is not so satisfying that the droplet is very easy to be absorbed due to low alkyl chain density.
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