Preparation and stabilization mechanism of carbon dots nanofluids for drag reduction

Abstract

During the development of low or ultra-low permeability oil resources, the alternative energy supply becomes a prominent issue. In recent years, carbon dots (CDs) have drawn much attention owing to their application potential in oil fields for reducing injection pressure and augmenting oil recovery. However, carbon dots characterized of small size, high surface energy are faced with several challenges, such as self-aggregation and settling. The preparation of stably dispersed carbon dots nanofluids is the key factor to guarantee its application performance in formation. In this work, we investigated the stability of hydrophilic carbon dots (HICDs) and hydrophobic carbon dots–Tween 80 (HOCDs) nanofluids. The influences of carbon dots concentration, sorts and concentration of salt ions as well as temperature on the stability of CDs were studied. The results showed that HICDs are more sensitive to sort and concentration of salt ions, while HOCDs are more sensitive to temperature. In addition, the core flooding experiments demonstrated that the pressure reduction rate of HICDs and HOCDs nanofluids can be as high as 17.88% and 26.14%, respectively. Hence, the HICDs and HOCDs nanofluids show a good application potential in the reduction of injection pressure during the development of low and ultra-low permeability oil resources.

Biogenic Synthesis of Fluorescent Carbon Dots (CDs) and Their Application in Bioimaging of Agricultural Crops

“…The negative zeta potential value of the nanoparticles may be attributed to the negatively charged functional groups present on the surface of the CDs created from fruit peel [ 51 , 74 , 75 , 76 ]. In the study of Wu et al [ 77 ], the observed zeta potential values were consistent with the reports of a stable CD synthesis [ 35 ]. The FT-IR analysis showed the peaks depicting the functional groups capped and stabilized the CDs.…”

Carbon Dots: Classification, Properties, Synthesis, Characterization, and Applications in Health Care—An Updated Review (2018–2021)

“…The zeta-potential signifies the degree of repulsion between the similarly charged and adjacent particles in a dispersion, thereby regulating the stability of CDs. Additionally, this method provides information about the properties of CDs, such as double layer characteristics with various hydrophilic functional groups (hydroxyl, carboxyl, and carbonyl) [185,198,199].…”

Solvent-controlled synthesis of hydrophilic and hydrophobic carbon dots

“…26 The amphiphilic structure of surfactants facilitates the affinity to water or lipid of hybrids. 27,28 Liu et al prepared amphiphilic CDs with blue and yellow dual emission, which enhanced the device performance of WLEDs. 27 Sarkar et al prepared hydrophobically modified CDs with different amine terminated small molecules as a surface modifier, and achieved the modulation of the cationic reverse micelle microstructure.…”