Fenton oxidation pretreatment enhanced the production efficiency of artificial humic acids from kitchen waste by hydrothermal process.

Abstract

The conversion of kitchen waste (KW) into artificial humic acids (AHAs) through hydrothermal processing represents a highly promising approach for sustainable resource recovery. Reducing hydrothermal duration while enhancing AHAs yield is of vital significance in most applications. This study for the first time employs Fenton oxidation as a pretreatment strategy for the hydrothermal humification of KW, effectively enhancing AHAs production efficiency. The pretreatment significantly reduces the hydrothermal processing time required to achieve the highest AHAs production from 6 h to 3 h at 180 °C, while simultaneously increasing AHAs yield from 14.37 ± 0.61 wt% to 18.43 ± 0.21 wt%. Comparative analysis of pretreatment-derived AHAs (FHA-3), non-pretreatment derived AHAs (HHA-6), and commercial humic acids (CHA) through various characterizations demonstrated structural similarity between FHA-3 and HHA-6, whereas both exhibited marked difference from CHA. Furthermore, the above characterization techniques provide critical insights into the mechanism of AHAs synthesis. Fenton oxidation treatment induces significant changes in the properties of raw materials, accelerating the formation of AHAs intermediates during hydrothermal humification and thereby enhancing AHAs production efficiency. This study provides a promising hydrothermal humification method for converting KW into AHAs and offers technical support for practical applications.