Enhanced Ozone Oxidation by a Novel Fe/Mn@γ−Al2O3 Nanocatalyst: The Role of Hydroxyl Radical and Singlet Oxygen

Catalytic ozonation is a potential alternative to address the dye wastewater effluent, and developing an effective catalyst for catalyzing ozone is desired. In this study, a novel Fe/Mn@γ−Al2O3 nanomaterial was prepared and successfully utilized for catalytic ozonation toward dye wastewater effluent components (dimethyl phthalate and 1−naphthol). The synthesized Fe/Mn@γ−Al2O3 exhibited superior activity in catalytic ozonation of dimethyl phthalate and 1−naphthol in contrast to Fe@γ−Al2O3 and Mn@γ−Al2O3. Quench and probe tests indicated that HO° contributed to almost all removal of dimethyl phthalate, whereas O3, HO°, and singlet oxygen participated in the degradation of 1−naphthol in the Fe/Mn@γ−Al2O3/O3 system. The results of XPS, FT−IR, and EPR suggested that HO° and singlet oxygen were generated from the valence variations of Fe(II/III)and Mn(III/IV). Moreover, the Fe/Mn@γ−Al2O3/O3 system could also have excellent efficacy in actual water samples, including dye wastewater effluent. This study presents an efficient ozone catalyst to purify dye wastewater effluent and deepens the comprehension of the role and formation of reactive species involved in the catalytic ozonation system.

Dimethyl Phthalate Induces Blood Immunotoxicity Through Oxidative Damage And Caspase-Dependent Apoptosis

Dimethyl phthalate (DMP), a low molecular weight phthalate ester, is present in ectoparasiticides, plastics, and insect repellants, has been linked to neurotoxic, reproductive, and endocrine disruptive responses. However, its blood immunotoxic effects and mechanism remain poorly understood. In this study, rats were exposed to graded concentrations of DMP through intragastric administration to assess the blood immunotoxic effects using a combination assay of biomarker, cytometry, and transcriptomics. DMP treatment altered the redox status of rats, causing that oxidative damage. Significantly decreased blood cell counts and disordered antibody and cytokine secretion were observed, suggesting the suppressed immune defense and destructed inflammatory regulation. Flow cytometry showed for lymphocytes, especially CD3+CD4+ T cells, apoptosis/necrosis occurred positively related to DMP exposure level. Transcriptomics revealed responses that were in line with oxidative damage effects. Overexpression of the Bcl-2 family genes and activation of the Fas/FasL pathway trigger downstream caspase cascade, causing reactive oxygen species signaling mediated apoptosis/necrosis. This is the first report on immunotoxic effects of low molecular weight phthalate esters.

Facile synthesis of hierarchical ZnO structure for photocatalytic degradation of dimethyl phthalate

A facile co-precipitation method was employed to fabricate hierarchical ZnO structure and characterized by various analytical instruments. The images of ZnO from field-emission scanning electron microscopy exhibited spheroidal morphology which composed of numerous layers of nanosheets and formed a hierarchical structure. Energy dispersive X-ray spectrum validated the presence of Zn and O atoms and its purity. X-ray diffraction pattern of ZnO revealed the establishment of hexagonal wurtzite structure. Optical property analysis disclosed that the as-fabricated ZnO had strong absorbance of wavelength from 350-410 nm with an absorption band edge of 367 nm. In this paper, the photocatalytic activity of hierarchical ZnO structure was confirmed by degradation of endocrine disrupting chemical, namely dimethyl phthalate under UV lamp irradiation. The photodegradation of dimethyl phthalate in aqueous solution over as-fabricated ZnO reached 55.9% after 60 min irradiation. The photocatalytic degradation of DMP obeyed the pseudo first-order kinetic reaction with a rate constant of 0.0166 min−1.