Sustainable Nanofluids\nConstructed from Size-Controlled\nLignin Nanoparticles: Application Prospects in Enhanced Oil Recovery

Lignin, a widely available, cost-effective, and structurally\nstable\nnatural polymer, has recently attracted significant attention due\nto its diverse potential applications. A promising approach is to\nprepare lignin nanoparticles (LNPs) as a substitute for conventional\nnanoparticles to fulfill a variety of functions. In this study, LNPs\nwith controlled size, regular morphology, and excellent dispersibility\nwere synthesized by using industrial alkali lignin. The antisolvent\nmethod was employed, utilizing an aqueous solution of the anionic\nsurfactant sodium apolyolefin sulfonate (AOS) as the antisolvent.\nSubsequently, the prepared LNPs were used to formulate nanofluids\nin combination with AOS and nonionic surfactant coconut diethanolamide\n(CDEA). The incorporation of LNPs has significantly enhanced the interfacial\nactivity of the resulting nanofluids, thereby improving their emulsion\nstabilization, spreading on quartz surfaces, and oil droplet removal\ncapabilities, which establish a strong foundation for the AOS/CDEA/LNPs\nnanofluid to achieve high performance in enhanced oil recovery (EOR),\nwhich was validated through microscopic visual physical model experiments.\nThe quartz crystal microbalance with the dissipation monitoring (QCM-D)\ntechnique was employed to investigate the adsorption of surfactants\nonto quartz surfaces. It was found that the incorporation of LNPs\nsignificantly reduces the adsorption loss of surfactants, presenting\na potential solution to overcome the challenges associated with surfactant\nadsorption in chemically enhanced oil recovery (EOR) processes, such\nas high cost and unreliable efficiency. This study reveals the good\nperformance of LNPs/surfactant nanofluids and provides a potential\napproach to the advancement of green, sustainable, and intelligent\nEOR technologies.