The petroleum industry produces a large volume of water-in-oil (W/O) emulsion annually, which has detrimental consequences for both the industry and the environment. Therefore, effective demulsification of these emulsions is crucial. In current work, a low-temperature demulsifier (EBTA) for W/O emulsions was synthesized using PET waste plastic as starting materials through a simple method. Chemical structure of EBTA was characterized by FT-IR and 1 H NMR. The demulsification performance was assessed using bottle-test method, and a comprehensive examination was conducted on the influence of EBTA concentration, settling time, temperature, pH value, and salinity on the demulsifying efficiency (DE). At a low temperature of 40 ℃ and a concentration of 250 mg/L, EBTA achieved a DE of 95.36% in an Emul30 emulsion, while a DE of 100% could be obtained in an Emul70 emulsion. Furthermore, EBTA demonstrated excellent tolerance for salts, acids and alkalis. In addition, the demulsification mechanism of EBTA was investigated using various techniques, such as interfacial tension (IFT), zeta potential, three-phase contact angle and coalescence time of droplets. The results revealed that EBTA had a lower IFT and was easily adsorbed on the oil–water interface. This led to the damage of the interface film and facilitated the oil–water separation. Due to the simple and safe synthesis process and remarkable demulsification performance, EBTA is a promising demulsifier for separating W/O emulsions.
Yitian Zhang,Jie Gao,Chao Jiang,Gang Luo,Jiajun Fan,James H. Clark,Shicheng Zhang
Chemical upgrading as a recycling technology for poly(ethylene terephthalate) (PET) waste plastic is an effective way to help solve the current challenges of plastic pollution. Catalytic methanolysis technology enables the depolymerization of PET into high-value dimethyl terephthalate (DMT) monomers under relatively mild conditions, thereby achieving closed-loop recycling of PET waste plastic. In this study, we compared the catalytic efficiency of Cu/SiO2 catalysts prepared by three different methods for the depolymerization of PET to DMT. Cu/SiO2-IM, prepared through the impregnation method, exhibited the highest activity, with PET conversion and DMT selectivity reaching 92.35% and 99.0%, respectively, at 200 °C without any initial gas pressure. The exceptional performance of Cu/SiO2-IM can be attributed to its small metal particles, substantial specific surface area, a high ratio of Brønsted acid sites (BAS) to Lewis acid sites (LAS) and the balance of Cu+ and Cu0 active sites on the catalytic surface. Furthermore, possible reaction mechanisms of Cu-based catalysts in the catalytic methanolysis of PET were investigated: Cu+ initiates the attack on the carbon groups along the long PET chain and enhances the nucleophilic attack during the depolymerization reaction, while Cu0 readily interacts with the hydroxyl group of methanol, leading to the formation of a new ester group between the oxygen atom in the hydroxyl group of methanol and the carbon atom in the CO group of PET polyester. This low-cost and high-efficiency catalytic methanolysis study provides a practical approach to PET waste plastic recycling.
危险品化学品经营许可证（带存储）