Reverse wood mimetic cryogel based on poly(itaconic acid) for continuous removal of methylene blue from complex water emulsion

Abstract

It is a challenging issue to simultaneously achieve high separation efficiency and high separation speed in a continuous flow separation process. Herein, inspired by reverse wood porous structure, the first example of artificial reverse wood-like polymer with horizontal aligned porous structure is shown in poly(itaconic acid) (PIA) cryogel fabricated by horizontal placement in situ cryo-polymerization technique. The vertical aligned porous PIA cryogel, as wood-like type control, is also constructed under the identical conditions except placement direction. After examined by a series of characterization, the horizontal PIA cryogel displays multiple similarities in comparison with the vertical one, including pore size, surface area, composition, carboxylic group content and wetting ability; but it shows significant difference in porous orientation and compressive property compared to the counterpart. Based on static and dynamic adsorption tests, methylene blue adsorption on the two columns obeys similar mathematics models, and the maximum static adsorption achieves 172.4 mg/g on the horizontal PIA column and 170.2 mg/g on the vertical PIA column based on Langmuir model, respectively; but in a continuous flow mode, the horizontal PIA column shows 126.2 mg/g dynamic adsorption, which is much higher than that obtained on the vertical one (76.3 mg/g) in terms of Thomas model. The adsorbent utilization efficiency of the reverse wood mimetic column is 73.2 % at 500 mg/L dye concentration and at 25 mL/min flow rate, which is superior to most of those reported in literature. The artificial wood-like column thereafter reaches high efficiency of cross flow filtration for rapid continuous removal of dye molecules from complex emulsion wastewater.