Oilfield wastewater contains a large number of metal ions (such as Ca 2+ and Cu 2+ ). Reinjection in oil wells without treatment would affect oil recovery. To remove Ca 2+ and Cu 2+ ions, we prepared a reusable Fe 3 O 4 /GO-COOH nanoadsorbent by the magnetization and carboxylation of graphene oxide (GO). The Ca 2+ and Cu 2+ removal percents of the nanoadsorbent reached 78.4% and 51% at 60 min, respectively. After five adsorption/desorption cycles, the nanoadsorbent retained high recovery rates (82.1% for Ca 2+ and 91.8% for Cu 2+ ) and removal percents (72.3% for Ca 2+ and 49.33% for Cu 2+ ). In the simulated indoor oil recovery test, oilfield wastewater treated with Fe 3 O 4 /GO-COOH could enhance oil recovery (EOR) by 11.0% compared with untreated oilfield wastewater. The novel magnetic nanoadsorbent could not only adsorb metal ions in oilfield wastewater effectively to enhance oil recovery (EOR) but could also be quickly recycled and reused, which shows promising application prospects in oil exploitation.
Wang Fei,Lü Hongmei,Wang Xiujun,Jing Bo,Duan Ming,Xiong Yan,Fang Shenwen
There are residual polymers in the oily wastewater produced from polymer flooding (OWPF); keeping the residual polymer in the water during the flocculation is meaningful and challenging. In this paper, a selective flocculant (denoted as PDC10) which can remove the oil while keeping partially hydrolyzed polyacrylamide (HPAM) in water was prepared by copolymerization of decyl two methyl vinylbenzyl ammonium chloride (C10MVBA) and dimethyl aminopropyl methacryamide (DMAPMA). By using oil removal and HPAM retention as evaluation indexes, the synthesis condition of PDC10 was optimized. The optimum PDC10 exhibited oil removal of 98.0% and HPAM retention of 80.5%. Its HPAM retention is much higher than that of a regular cationic flocculant. Measurements of zeta potential, interfacial tension, interfacial dilational modulus and a dual polarization interferometry (DPI) test were carried out for investigating the flocculation mechanism of PDC10. The mechanism of PDC10 was that it can bridge and flocculate oil droplets by electrostatic interaction and hydrophobic interaction. It also preferred to distribute at the interface, and its interaction with HPAM in bulk water was weak, which confirms its selective flocculation properties.
Removing emulsified oil from surfactant-polymer-flooding (SPF) oily sewage is a tough problem during oil field exploitation as the viscosity and emulsification degree of the oily sewage dramatically increased with the addition of surfactant and polymer in the recovery process. Herein, alkylated chitosan (CS-NaOH) sponges with uniform porous structure were prepared by freeze-drying and water bath heating in sodium hydroxide solution. With the superhydrophilicity and negative surface charges, the CS-NaOH sponges exhibited excellent SPF oily sewage separation performance by means of the aggregation-induced demulsification mechanism. Especially, the 3 wt% CS-NaOH sponges showed the SPF oily sewage separation performance with separation efficiency as high as 98.11% and separation flux up to 12,100 L·m −2 ·h −1 ·bar −1 . Furthermore, the acetyl group in the chitosan molecule was converted to amino group through the deacetylation reaction triggered by alkalization, resulting in more intermolecular hydrogen bonds formed in CS-NaOH sponges. Therefore, the CS-NaOH sponges possessed extraordinary stability in comparison to the CS sponges without alkalization treatment, including ultrahigh compressibility, superior fatigue resistance and ranking chemical stability, which provided a guarantee for the subsequent long-term practical application. Graphical abstract
危险品化学品经营许可证（带存储）