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Through literature research, the unplugging mechanism of various wellbore unplugging fluids was analyzed, and the application progress, advantages and disadvantages of various types of commonly used wellbore deplugging fluids were summarized. The research progress of new deplugging working fluids such as organic deplugging working fluid, organic slow-release microlactic acid deplugging working solution and composite deplugging working fluid was introduced. The problems existing in the preparation and practical application of plugging fluids were analyzed, and the development trend of unplugging liquids in the future was proposed. [ABSTRACT FROM AUTHOR]

The novel composite, Fe3O4@SiO2@mSiO2-PW12/Ag, was successfully prepared by in situ loading Ag nanoparticles (Ag NPs) on the surface of grafted phosphotungstate (denoted as PW12) Fe3O4@SiO2@mSiO2via a photoreduction deposition method. PW12 not only acts as a reducing agent and stabilizer for Ag NPs but also as a bridge to link Ag NPs and the SiO2 shell in the loading process. Its activity toward the photodegradation of methyl orange (MO) and photoreduction of Cr2O72− anions was evaluated. Experimental results showed that Fe3O4@SiO2@mSiO2-PW12/Ag with 5.3 wt% Ag loading and 18.65 wt% of PW12 exhibits the highest photocatalytic efficacy, and complete degradation of MO and 91.2% photoreduction of Cr(VI) were realized under simulated sunlight for 75 min, respectively. The enhanced catalytic activities of the composite are due to its high specific surface area, the synergistic effect among the components and the formation of a heterojunction of PW12/Ag. The possible enhanced photocatalytic mechanism is proposed. The catalyst is durable and can be easily recovered using a magnet for recycling without a significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]