Comparative analysis of humic acid, lignin and lignite-based hydrogels for methylene blue dye removal. Indian Journal of Chemical Technology (IJCT), [S. l.], v. 33, n. 3, p. 391–400, 2026. DOI: 10.56042/ijct.v33i3.20751. Disponível em: https://or.niscpr.res.in/index.php/IJCT/article/view/20751. Acesso em: 15 may. 2026.