Enhanced superhydrophobicity and durability of modified cotton cloth for efficient oil-water separation

Abstract

The development of simple, low-cost, and efficient oil/water separation membranes is still a major challenge in the field of wastewater treatment. In this study, an oil/water separation membrane is prepared based on low-cost cotton cloth (CF) through a simple solution soaking treatment without using organic solvents. Pristine CF is treated first with concentrated alkali and then chemically grafted by sodium methyl silicate (SMS) onto the surface to obtain oil/water separation membrane (SMS-O-CF). This process not only increases the roughness of the CF but also endows the surface with superhydrophobicity due to the outward extension of methyl groups, resulting in a water contact angle (WCA) of 155° and good self-cleaning ability. The SMS-O-CF achieves efficient separation for various oil/water mixtures and maintains a separation efficiency up to 96 % and a flux of over 11,557 L·m−2·h−1 after 220 cycles under neutral conditions. Moreover, the modified CF also exhibits excellent acid/alkaline resistance and wear resistance. Regardless of the 12 h acid/base immersion, 100 min water wash, or 200-cycle mechanical abrasion, SMS-O-CF still exhibits high flux and separation efficiency. Raw material cost for preparing SMS-O-CF is as low as 1.0 dollar/m2. The preparation of SMS-O-CF has provided a green manufacturing method for developing low-cost and efficient oil–water separation membranes.