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Natural cellulose microfiltration membranes for oil/water nanoemulsions separation

Hu, Meng-Xin, Niu, Hong-Mei, Chen, Xian-Lin, Zhan, Hua-Bao
Colloids and surfaces 2019 v.564 pp. 142-151
cellulose, coagulation, colloids, hydrophilicity, lard, microfiltration, nanoemulsions, peanut oil, porosity, separation, temperature, wastewater, wastewater treatment
Nanoemulsions are highly stable in the solutions. Separation of nanoemulsions is the most intractable problem in the wastewater treatment. The development of a low-cost, high-performance, bio-based membrane has been attempted to treat oily wastewater containing oil/water nanoemulsions. In this work, cellulose microfiltration membrane with inherent hydrophilic and underwater oleophobic behaviors were prepared by thermally induced phase separation (TIPS) using a lower critical solution temperature (LCST) system. High coagulation temperature enables rapid phase separation and prepares membrane with big pore size and loose pore structure, mainly controlled by the LCST-TIPS process. With the increase in the coagulation temperature from 10 °C to 50 °C, the water flux of cellulose membranes increased 7 times. Inherent hydrophilic and underwater oleophobic behaviors of cellulose makes the prepared cellulose microfiltration membranes displaying high efficiency in separation of oil/water nanoemulsions, including the lard and the food wastewater nanoemulsions with drop size in the range of 6–60 nm. Oil rejections are about higher than 99% to the peanut oil and the pump oil nanoemulsion and higher than 98% for the lard and the food wastewater nanoemulsions. These results demonstrate that the cellulose microfiltration membranes can be used for oil/water nanoemulsions separation in a green, economical, and efficient way.