Removal of anionic and cationic dyes from aqueous solution using thermo-and pH-responsive amphiphilic copolymers

Amphiphilic copolymers exhibiting thermally induced phase segregation in water hold great potential as smart flocculants for water purification. Herein, we report the preparation of thermo-and pH-responsive copolymers based on oligo(ethylene glycol) methacrylate (OEGMA), dimethylaminoethyl acrylate (DMAEA) and penta-fluorostyrene (PFS), and their use as thermally induced adsorbents for the removal of anionic and cationic dyes from water. The copolymer self-assembly behaviour in water was first studied as a function of concentration and pH. Then, the potential to remove thiazole yellow G (TYG) and rhodamine B (RhB) was investigated as a function of pH and dye concentration, highlighting that dye removal is mediated by hydrophobic and electrostatic in-teractions. As regards TYG, at pH 4 a removal capacity (RC) of about 80 mg/g, corresponding to a 97 % dye removal efficiency, was achieved at 800 mg/L TYG. In the case of RhB, a maximum RC value of 32 mg/g was obtained at pH 10. The results reported herein show that these copolymers represent a versatile platform to remove water-soluble organic dyes depending on pollutant concentration and pH conditions.

Automated summary

In this study, thermo- and pH-responsive copolymers were prepared and used as adsorbents to remove organic dyes from water. The copolymers exhibited self-assembly behavior and achieved high efficiency in dye removal through hydrophobic and electrostatic interactions.