Amino-modified banana nanocellulose aerogels with quick pH-responsive switchable wettability for oil-water separation

With the rapid development of the maritime industry, oily wastewater discharges and oil spills cause acute environmental challenges. Currently, cellulosic materials with switchable wettability have received increasing interest for oil-water separation. Moreover, work efficiency needs to be improved with a shorter response time. To realize these, dimethylaminoethyl methacrylate (DMAEMA) and methyltrimethoxysilane (MTMS) synthesized pH-responsive copolymer (DMAEMA-co-MTMS) which grafted banana nanocellulose fiber made from wasted pseudostem to achieve the pH-responsive aerogel (BCNA-DcoM). BCNA-DcoM exhibited hydrophilic/submerged lipophobicity under acidic conditions and hydrophobic/lipophilic under alkaline conditions. A response time of 3 s and a contact angle of 135 degrees were shown when the mass ratio of banana nanocellulose suspension, MTMS, and DMAEMA-co-MTMS was 5:3:9. Moreover, BCNA-DcoM possessed favorable mechanical friction properties, salt resistance (25% NaCl), compression resilience (50 cycles of compression at 60% strain), switchable wettability (>30 cycles), and highly efficient separation performance (>96%). The adsorption capacity of BCNA-DcoM for oil is 80-184 times the initial weight of the aerogel based on the different oil densities. For practical applications, BCNA-DcoM could continuously separate oil-water mixtures with the constant-flow pump. The present work provides more possibilities for rapidly treating industrial oily wastewater with low-cost and ecological banana pseudostem materials.