One-step hydrothermal co-carbonization of waste paper with phytic acid for efficient removal of Cr(VI)

The formation of phytic acid decorated waste paper-derived hydrothermal carbon (WPC-P) were achieved. • The introduction of phytic acid enables to improve the oxygen-containing groups and specific surface area of WPC-P. • The phytic acid modified WPC-P exhibited upgraded adsorption activity of Cr(VI). • The mechanism of Cr(VI) removal was generated by electrostatic, chelation, and reduction interactions. Biomass-derived hydrothermal carbon has garnered considerable interest as a promising approach for heavy metal wastewater treatment. In this study, hydrothermal carbon derived from waste paper and coupled with phytic acid (WPC-P) was synthesized via a one-step hydrothermal process as an effective adsorbent for Cr(VI) removal. Characterization results indicated that P and O were dispersed uniformly on the surface of WPC-P. The introduction of phytic acid could greatly increase the specific surface area and number of active functional groups. The results of adsorption tests indicated that WPC-P exhibited highly efficient removal performance for Cr(VI) with maximum uptake of 174.05 mg·g −1 . The adsorption capacity of WPC-P was 10 times higher than that of WPC at 2 h. Analysis of the experimental data using adsorption kinetic and isotherm models revealed that the adsorption process of WPC-P fitted both the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model well. After five consecutive adsorption-desorption cycles, the WPC-P retained about 87% of its initial capacity. The enhanced adsorption performance, ascribed to the introduction of phytic acid, could be attributed to the complexation, electrostatic interactions and reduction reactions induced by active functional groups on WPC-P. This work reported a simple method to prepare carbon adsorbents from biomass waste, which showed great potential for treating chromium-containing wastewater.