Co-pyrolysis of polyester and cotton via thermogravimetric analysis and adsorption mechanism of Cr(VI) removal by carbon in aqueous solution

[Display omitted] •The synergistic effect of co-pyrolysis of cotton and polyester was studied by TGA.•The adsorption capacity was enhanced by ZnCl2 modification.•Cr(VI) was reduced to less toxic Cr(III) via C = O and –OH functional groups.•The adsorption mechanism was obtained by experiments and characterization. The purpose of this study is to explore the synergy effect of cotton and polyester in pyrolysis process and make full use of the carbon as an adsorbent for Cr(VI) removal. The co-pyrolysis and decomposition characteristics of cotton and polyester were studied by thermogravimetric analysis (TGA) to analyze the synergy effect between them. The physical and chemical characteristic of polyester-cotton carbon with the best synergy ratio were detected with SEM-EDS, BET, XRD, FTIR and XPS. The FTIR and XPS before/after adsorption of Cr(VI) accompanied by kinetic fitting and adsorption isotherm were applied to analyze the adsorption mechanism, and adsorption condition were also discussed. The adsorption mechanism includes electrostatic action, reduction action and complexation. The study shows that the polyester-cotton carbon had great application potential to remove Cr(VI) by using the synergy effect of cotton and polyester.