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Abstract: This work describes the oxidation of ammonia (NH3) at temperatures between 423 and 673K by selective catalytic oxidation (SCO) over a Pt–Rh nanocomposite catalyst that was prepared by the co-precipitation of H2PtCl6 and Rh(NO3)3 in a tubular fixed-bed flow quartz reactor (TFBR). The catalysts were characterized using TEM, XRD, PSA, and CV. The experimental results reveal that at a temperature of 673K and an oxygen content of 4%, approximately 98% of the NH3 was removed by catalytic oxidation over the Pt–Rh nanocomposite catalyst. N2 was the main product of the NH3-SCO process. The Pt–Rh nanocomposite-induced cytotoxicity to the human lung cell line, MRC-5, was tested, and cell survival was determined using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetra-zolium (MTS) analysis in vitro. These results demonstrated that the Pt–Rh nanocomposite catalyst is only weakly cytotoxic to human lung cells. [Copyright &y& Elsevier]

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]

Groundwater contamination by organic aromatic compounds such as gasoline fuel is a serious worldwide problem because of their carcinogenic and mutagenic potential. This study evaluated the use of Fe 3 O 4 − carbon black (CB) composites for persulfate (PS) oxidation of benzene, toluene, ethylene, and xylene (BTEX) and methyl tert -butyl ether (MTBE) compounds from the aqueous solution. The characterization results of environmental scanning electron microscopy coupled with energy-dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and a superconducting quantum interference device magnetometry evidenced the successful synthesis of Fe 3 O 4 − CB composites. In addition, the in vitro cytotoxic activity and apoptotic response of these composites were investigated before and after the Fe 3 O 4 −CB/PS processes test of the BTEX and MTBE samples was performed. The effects of various operating parameters were evaluated to optimize the oxidation process, including the PS concentration, initial pH, and Fe 3 O 4 − CB amount. The results showed that increasing PS and Fe 3 O 4 − CB dosage could accelerate BTEX and MTBE oxidation when PS and Fe 3 O 4 − CB concentrations increased to 15 g L −1 and 1.0 g L −1 , respectively, at a pH of 3.0. The degradation rate of BTEX and MTBE was strongly pH-dependent. Methyl thiazolyl tetrazolium assay was employed to perform a cytotoxicity study after Fe 3 O 4 −CB/PS processing treatment of BTEX and MTBE degradation products on the zebrafish ( Danio rerio ) embryonic cell line (ZF4), which revealed that a weak effect and apoptosis in cell viability ultimately leads to cell death. The results suggested that Fe 3 O 4 −CB assisted persulfate oxidation without elevating the temperature is a suitable and economic alternative for the ex-situ treatment of BTEX- and MTBE-contaminated aquatic environments. [ABSTRACT FROM AUTHOR]