[Degradation Mechanism of Tetracycline Using Fe/Cu Oxides as Heterogeneous Activators of Peroxymonosulfate].

A green, highly efficient, and porous copper-ferrite heterogeneous catalyst (Fe-Cu-400) with good magnetism was synthesized via a coprecipitation method. The catalysts were characterized using XRD, BET, FESEM, and EDS. The performance of Fe-Cu-400 as a catalyst was evaluated by activating peroxymonosulfate (PMS) for degradation of tetracycline (TC) in aqueous solution and investigating the influence of several water parameters. The Fe-Cu-400/PMS system showed a greater TC degradation ability, and the degradation rate of TC was enhanced with an increase in the PMS concentration and the initial pH of the coupled Fe-Cu-400/PMS system. Anions including H2PO4-, HCO3-, and Cl- promoted TC degradation, whereas NO3- showed a low inhibitory influence. In addition, Fe-Cu-400 exhibited excellent reusability towards activating PMS for TC degradation after five runs of tests. Possible mechanisms of the activation of PMS by Fe-Cu-400 and the main reactive species were proposed based on radical identification tests and XPS analysis. Furthermore, a potential degradation pathway was proposed that included hydrolysis and sequential removal of N-methyl, hydroxyl, and amine functional groups according to the results of LC-MS and TOC detections.

Investigation of biosurfactant-producing indigenous microorganisms that enhance residue oil recovery in an oil reservoir after polymer flooding.

Three biosurfactant-producing indigenous microorganisms (XDS1, XDS2, XDS3) were isolated from a petroleum reservoir in the Daqing Oilfield (China) after polymer flooding. Their metabolic, biochemical, and oil-degradation characteristics, as well as their oil displacement in the core were studied. These indigenous microorganisms were identified as short rod bacillus bacteria with white color, round shape, a protruding structure, and a rough surface. Strains have peritrichous flagella, are able to produce endospores, are sporangia, and are clearly swollen and terminal. Bacterial cultures show that the oil-spreading values of the fermentation fluid containing all three strains are more than 4.5 cm (diameter) with an approximate 25 mN/m surface tension. The hydrocarbon degradation rates of each of the three strains exceeded 50%, with the highest achieving 84%. Several oil recovery agents were produced following degradation. At the same time, the heavy components of crude oil were degraded into light components, and their flow characteristics were also improved. The surface tension and viscosity of the crude oil decreased after being treated by the three strains of microorganisms. The core-flooding tests showed that the incremental oil recoveries were 4.89-6.96%. Thus, XDS123 treatment may represent a viable method for microbial-enhanced oil recovery.