Efficacy and cytotoxicity of engineered ferromanganese-bearing sludge-derived biochar for percarbonate-induced phthalate ester degradation.

Phthalate esters (PAEs) are a group of ubiquitous organic environmental contaminants. Engineered ferromanganese-bearing sludge-derived biochar (SDB), synthesized using one-step pyrolysis in the temperature range between 300 and 900 °C, was used to enable Fenton-like processes that decontaminated PAE-laden sediments. SDB was thoroughly characterized using scanning electron microscopy energy-dispersive spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller surface area, thermogravimetric analysis, Raman spectroscopy, Fourier-transform infrared spectroscopy, electron paramagnetic resonance, X-ray photoelectron spectroscopy, and fluorescence excitation–emission matrix spectroscopy coupled with parallel factor analysis. The maximum PAE degradation was remarkable at 90% in 12 h at pH 6.0 in the presence of 1.7 g L−1 of SDB 900. The highly-effective PAE degradation was mainly attributed to the synergism between FeO x and MnO x , which strengthened the activation of percarbonate (PC) via electron transfer, hydroxy addition, and hydrogen abstraction through radical (HO•) and nonradical (1O 2) oxidation mechanisms, thereby facilitating PAE catalytic degradation over SDB in real sediments, which clearly proved the efficacy of ferromanganese-bearing SDB and PC for the remediation of contaminated sediments. The cytotoxicity exhibited by human skin keratinocyte cells exposure to high SDB concentration (100–400 µg mL−1) for 24–48 h was low indicating insignificant cellular toxicity and oxidative damages. This study provides a new strategy for freshwater sludge treatment and reutilization, which enables a water-cycle-based circular economy and waste-to-resource recycling. [Display omitted] • Sludge-derived biochar (SDB) was synthesized by pyrolysis of freshwater sludge. • SDB activation of percarbonate effectively degraded phthalate ester (PAE) in sediments. • Fe and Mn minerals in SDB played a synergistic role on PAE degradation. • Radical (HO•) and nonradical (1O 2) were involved in PAE degradation. • Cytotoxicity in HaCaT cells exposure to SDB was low. [ABSTRACT FROM AUTHOR]