Industrial wastewater treatment has emerged as a significant global challenge. Although physical adsorption offers advantages such as effective contaminant removal and operational simplicity, it often entails high consumption of adsorbent materials and elevated costs. Because of its superparamagnetic, small particle size, large specific surface area and easy recovery characteristics, Fe₃O₄ shows broad potential in the field of adsorption, but its application alone still has some limitations. This paper aims to review the preparation and application of magnetic composites based on Fe₃O₄ as a green and efficient adsorbent in wastewater treatment, in order to deal with the current problems of high cost and difficult recovery of adsorption materials. The main synthesis methods for magnetic activated carbon, magnetic cyclodextrin, and magnetic cellulose composites were introduced, followed by an overview of their use in the adsorption of heavy metals and organic pollutants. Additionally, an analysis was conducted on the advancements in the application of magnetic separation and regeneration technologies. The results indicate that Fe₃O₄ composite material has good performance in adsorption efficiency, environmental protection and cost control. Fe₃O₄ composites have shown unique advantages as potential adsorbents. It is suggested that Fe₃O₄ composite adsorption materials with low cost and high adsorption capacity should be further developed to promote its transformation from laboratory to engineering application.

Dome top tanks are important facilities for oil storage, and in order to reduce the evaporation loss of storage tanks, it is necessary to conduct research on their evaporation loss mechanism. Establishing a UDF for the absorption of heat flux at different times in a dome roof tank, and using FLUENT 19.0 software to simulate and analyze the effects of solar radiation intensity, oil storage height, and oil storage time on the diffusion of oil and gas inside the tank, the simulation results showed that: the gas temperature distribution inside the tank was uneven, with a vertical distribution of high and low, and the average gas temperature inside the tank decreased with the increase of oil storage height. The mass fraction of oil and gas in the tank is similar at the same oil level height, with the highest mass fraction on the oil surface. The vapor mass fraction is positively correlated with the oil storage height and storage time. The maximum pressure value of the gas inside the tank in a day first increases and then decreases, gradually increasing with the height of the liquid level. This study provides a basis for evaluating the evaporation loss of storage tanks and designing and managing oil and gas recovery systems

Using molecular dynamics, the lowest energy configurations of n?dodecane, n?octadecane, and n?nonadecane were constructed, and the interactions between oil molecules and wax molecules were studied at different water contents (mass fractions). The molecular dynamics model of crude oil emulsion system based on different mass fraction water content was constructed. The effect of water molecules dissolved in the system on the viscosity of waxy crude oil was studied. The radial distribution functions of wax molecules in different water content systems were compared. The results show that carbon number is the main factor to determine the interaction energy between crude oil molecules. With the increase of water content, the distance between molecules increases, while the interaction energy decreases. After water molecules are dissolved in the system, the distance between wax molecules and electrostatic interaction become larger, the distribution of wax molecules becomes disordered, and the flow characteristics of crude oil are improved.

During the extraction and transportation of waxy crude oil, paraffin will deposit on the wall, forming wax deposition. In recent years, microbial wax removal and prevention technology has been widely studied for its economic and environmental advantages. Five strains of bacteria were screened from crude oil sludge, and through the determination of their paraffin degradation rate and surface hydrophobicity, the bacterium B3 was selected and identified as Bruella intermedia. The experimental results showed that bacterial B3 had the best growth activity at a temperature of 40 ℃, an initial pH of 6, and a shaking table speed of 160 r/min, and had the best degradation effect on paraffin at this time. When bacteria B3 grows and metabolizes with paraffin as a carbon source, they can produce lipopeptide biosurfactants, with an emulsification coefficient of 52.5% for liquid paraffin. After 7 days of interaction between bacteria B3 and crude oil, the wax prevention rate reached 77.2%, and the viscosity reduction rate reached 50.2% at 41 ℃. Bacterial B3 can degrade paraffin, improve crude oil fluidity, and reduce wax deposition.

Microbial dewaxing of crude oil is an efficient and simple method. In order to further improve the paraffin degradation rate of microorganisms, two strains L and K were used to form paraffin degradation mixed bacteria, and their degradation conditions were optimized. The factors affecting the degradation of mixed bacteria (culture temperature, initial pH value of culture medium, salt concentration, and V（L strain ）/V（K strain）) were determined by orthogonal experiment and single factor experiment. Box-Behnken method was used to design four?factor three?level experiment and response surface optimization, and a mathematical model was established to explore the best conditions for the degradation of paraffin by mixed bacteria. The experimental results showed that the influence of four single factors is as follows: V（L strain）/V（K strain）>culture temperature>salt concentration>initial pH value of culture medium. Their primary term, secondary term and individual interaction term had significant influence on the paraffin degradation rate. The optimal experimental operating conditions for the mixed bacteria to degrade paraffin were determined as follows: culture temperature 37.2 ℃, initial pH value of culture medium 7.3, salt concentration of culture medium 1.2%, ratio of mixed bacteria V（L strain）/V（K strain）=1.0∶1.6, and paraffin degradation rate 58.67%. The mixed bacteria were used to act on crude oil under the optimized conditions, and the biodegradation rate was 41.38%,have good application prospects.

Aiming at the periodic characteristics of severe slug flow an experimental study was carried out through the downward?riser system. Based on the experimental data and the variation of pressure in the pipe, the variation rule of the severe slug flow period was analyzed and verified reciprocally with the calculation model results. It turned out that the flow state in the tube would change under different experimental parameters such as the inclination angle of the downdip tube, the gas phase conversion velocity or the liquid phase conversion velocity. The time of the slug eruption and slug reflux was basically changeless on account of the height of the riser was invariant, so the period of severe slugging depends on the time of slug formation and slug outflow stages. And it was mainly affected by the inclination angle of downward riser, gas superficial velocity or liquid superficial velocity.

The influence of sulfate reducing bacteria (SRB) and CaCO₃ scale layer on the corrosion behavior of 20^# steel was studied by laboratory simulation experiment. The uniform corrosion rate was studied by corrosion weight loss method.The corrosion electrochemical behavior of 20^# steel in the injected aqueous solution was studied by electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP). The morphology and composition of corrosion products on the surface of 20^# steel were analyzed by scanning electron microscopy (SEM), EDS and Raman spectroscopy. The pitting pit depth of 20^# steel was analyzed by laser confocal microscopy (CLSM). The results show that there is a synergistic effect between SRB and CaCO₃ scale layer. The porosity of CaCO₃ scale layer and the anaerobic environment under the scale layer provide convenient conditions for the adhesion and growth of SRB. The inoculation of SRB can promote the uniform corrosion and local corrosion of 20^# steel under the CaCO₃ scale layer.

The geometric model of a certain oil and gas mixed transportation pipeline was established with OLGA software, and the transient flow law during the pipeline shutdown and restart process was studied. First, the distribution characteristics of temperature, pressure and liquid holdup along the pipeline during steady state operation were analyzed, and the location of the minimum temperature and the location of the maximum pressure along the pipeline were determined. The influence of environmental temperature and shutdown time on operating parameters were analyzed. The safe shutdown time when the minimum temperature temperature is higher than its freezing point was determined. In the actual operation process, the shutdown time should not exceed the safe shutdown time, otherwise problems such as pipeline condensation and excessive starting pressure will easily occur, which threaten the safety of the pipeline.