Removal of methylene blue (MB) and vat dyes from wastewater using nanostructured PANI, PPy, and PTh: a comparative study

Abstract The removal capabilities of organic pollutants methylene blue (MB) and textile dyes, especially the vat dyes from wastewater were reported using polyaniline (PANI), polypyrrole (PPy) and polythiophene (PTh) under direct sunlight irradiation. The comparative removal competence of these polymers is reported in the present work. Among the three polymers, PANI demonstrated nanofiber morphology, PPy showed a spherical-shaped structure, and the agglomerated and irregular morphology for the PTh was appreciated, and investigated by field-emission scanning electron microscopy (FESEM). However, the diameter of the particles remains 20–200 nm for these three polymers. The experimental findings for the photocatalytic performances of all three polymers demonstrated that PANI showed 97 % removal of MB in 660 min whereas, PPy and PTh showed 96 and 94 % removal, respectively. The results for removing vat dyes are 41 % for PANI, 44 % for PPy, and 45 % for PTh. Thus, PANI, PPy, and PTh are able to remove both MB and vat dyes, however the % of vat dyes removal is lower compared to MB. These outcomes may provide a new perception of conducting polymers as photocatalysts for organic dye removal in water purifications.