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aThis research aims to clarify the role of magnesium oxide as a catalyst in the catalytic ozonation process. Nano-sized magnesium oxide was prepared by the sol-gel method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The catalytic performance of magnesium oxide was tested for the removal of phenol. The effect of initial pH, MgO nanocrystal amount, radical scavenger (t-butanol) and R ct was investigated to understand the catalytic ozonation mechanism of magnesium oxide with ozone. Experimental results illustrated that nano-sized magnesium oxide presented significant performance for the ozonation and catalyzed the removal of phenol from aqueous solution by ozonation with a radical pathway involving hydroxyl radicals, which was due to the activity of surface basic groups from magnesium oxide where the conversion of ozone to hydroxyl radicals occurred. Fourier transform infrared spectroscopy (FT-IR) and isoelectric point (IEP) analysis was applied to analyze the surface properties of the prepared nano-magnesium oxide. Activation energy (E a ) was calculated based on the Arrhenius principle equation. It reveals that phenol could enhance the density of surface hydroxyl groups and the introduction of magnesium oxide into the ozonation system does not alter the activation energy. Therefore, the prepared powder was found to be an efficient and promising catalyst for ozonation.

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The feasibility of methyldiethanolamine (MDEA) degradation in thermally activated PS system was evaluated. Effects of the PS concentration, pH, activation temperature and reaction time on MDEA degradation were investigated. Simultaneity, the thermodynamic analysis and degradation process were also performed. Several findings were made in this study including the following: the degradation rates of MDEA in thermally activated PS systems were higher than other systems. MDEA could be readily degraded at 40°C with a PS concentration of 25.2 mM, the process of MDEA degradation was accelerated by higher PS dose and reaction temperature, and MDEA degradation and PS consumption followed the pseudo-first-order kinetic model. The thermodynamic analysis showed that the activation process followed an endothermic path of the positive value of [Formula: see text] and spontaneous with the negative value of [Formula: see text], high temperature was favorable to the degradation of MDEA with the apparent activation energy of 87.11 KJ/mol. Combined FT-IR with GC-MS analysis techniques, MDEA could be oxidative degraded after the C-N bond broken to small molecules of organic acids, alcohols or nitro compounds until oxidized to CO and HO. In conclusion, the thermally activated PS process is a promising option for degrading MDEA effluent liquor.

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Currently, research on oily sludge treatment mainly focuses on optimizing the deoiling effect and research on the deoiling mechanism, and the influence of petroleum components on the properties and treatment of oily sludge is rarely considered. Therefore, in this study, petroleum substances in three types of oil sludge were eluted using the biosurfactant cleaning technology, and the influence of petroleum components on the cleaning process was explored. The results showed that the biosurfactants rhamnolipid and sophorolipid had a synergistic effect, and the oil-removal rate was as high as 92.2% when the SL mass fraction was 0.4 in the compound biosurfactant. Three types of oily sludge, wellsitelanding sludge, pipeline-landing sludge, and tank-bottom sludge, were cleaned by the compound biosurfactant; the results showed that the residual petroleum substance in liquid and solid phases, the turbidity value, and the zeta-potential value of the supernatant of oil sludge samples after cleaning increased with the increase in the heavy components of the oily sludge, and the oil-removal rate decreased gradually. After cleaning, the average relative molecular weight of the three oil phases increased with the heavy components, which was increased by 1.83, 4.83, and 10.72%, respectively, and the increase in molecular weight increased the difficulty of cleaning. After cleaning, the retention time and peak intensity of the oil sample changed significantly, and it had a stronger elution effect on low-molecular-weight alkanes. It was found that the compound biosurfactant had a good elution effect on polycyclic aromatic hydrocarbons, but the increase in the content of heavy components and the increase in aromatic rings increased the difficulty of cleaning. Moreover, it was found that the compound biosurfactant could not completely elute the petroleum substances on the surface of solid particles, and the asphaltene components in the oil phase were more difficult to elute than other components.

The best recovery of Nannochloropsis oculata from the culture broth and effect on content of lipids

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