Unveiling the Potential of Novel Struvite-Humic Acid Composite Extracted from Anaerobic Digestate for Adsorption and Reduction of Chromium

A novel struvite-humic acid composite (S-HA) was derived from an anaerobic digestate and evaluated for the adsorption and reduction of chromium [Cr (VI)] in this study. The results indicated that the struvite-humic acid composite (S-HA) contains higher contents of oxygen-containing and aromatic functional groups (47.05% and 34.13%, respectively) and a higher specific surface area (19.3 m(2) g(-1)). These special characteristics of S-HA contributed to its higher adsorption capacity (207.69 mg g(-1) and 254.47 mg g(-1) for pseudo-first and second-order kinetic models, respectively) for chromium. Furthermore, XPS analysis showed that a portion of the bonded Cr (VI) was reduced to Cr (III) by carboxyl and hydroxyl functional groups, which oxidized and changed into ketone and phenol functional groups. Based on the findings, it was concluded that the phosphate-humic acid composite has an outstanding chromium adsorptive and reduction capacity. However, more research is needed to fully understand the potential of the struvite-humic acid composite for chromium adsorption and reduction.

Automated summary

A novel struvite-humic acid composite (S-HA) derived from an anaerobic digestate showed high adsorption and reduction capacities for chromium (VI). The composite contained higher amounts of oxygen-containing and aromatic functional groups and had a larger specific surface area. XPS analysis revealed that a portion of the bonded Cr (VI) was reduced to Cr (III). These findings demonstrate the outstanding potential of the struvite-humic acid composite for chromium adsorption and reduction.