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The development of advanced purification technology of Pb(Ⅱ)-containing sewage water is of great significance. The adsorption technology is one of the cost-effective treatments. As an advanced adsorbent, graphene oxide (GO) has aroused great interests owing to its large specific surface area, abundant oxygen-containing groups and stable chemical properties. However, the Pb(Ⅱ) adsorption performance of bare GO is limited, modification strategies are needed to optimize its properties. Up to now, thousands of researches on Pb(Ⅱ) adsorption with modified absorbent have been reported, whereas the systematic review of GO-based adsorbents focusing on Pb(II) treatment has yet to be documented. Therefore, this review summarizes recent advances on the development of modified GO-based materials for the adsorption of Pb(II) from water. The modification methods of GO including group modification, morphology regulation and nanomaterial loading and their Pb(Ⅱ) removal performances are highlighted. In addition, the adsorption mechanism of Pb(Ⅱ) on the adsorbent surface, the effects of the factors on the Pb(Ⅱ) adsorption performance, and the techno-economics of the GO-based adsorbents are discussed. The reality, challenges, and perspectives of GO-based sorbents for Pb(Ⅱ) removing are finally proposed to facilitate the sustainable development of the water purification field.

Graphene oxide (GO), as a derivative of graphene, is rich in reactive functional groups on its surface for modification, and the modified graphene oxide (M-GO) has excellent special properties. In this paper, the improved Hummer’s method was used to analyze GO by adjusting the amount of oxidant (potassium permanganate), oxidation time, and temperature, using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and laser particle size measurement. The successful synthesis of dimension-controlled GO in the range of 630–1000 nm was confirmed. On this basis, modified graphene oxide (O-M-GO) was prepared by grafting octadecyltrimethoxysilane (OCT). The successful synthesis of O-M-GO was confirmed by FT-IR and XRD. Through a contact angle test, the contact angle of GO before modification was 80 ± 0.5° and that of O-M-GO after modification was 105 ± 0.5°. Combined with SEM analysis, the change in the wettability of O-M-GO was clarified. Core flow test results showed that after O-M-GO was injected into the core, the subsequent brine injection pressure decreased by 14.21%, and the permeability was 1.166 times that before the brine injection. When the injection concentration was 50 mg/L, the drag reduction rate was 14%.

The two-dimensional axisymmetric nozzle is initialized by two methods which are the hybrid initialization method of the commercial computational fluid dynamics software Fluent and the initialization program based on the one-dimensional isentropic theory. The first-order upwind format is combined with the SA model to solve the two-dimensional axisymmetric nozzle under the same boundary conditions. The convergence process is obtained in the process of numerical calculation, and the influence of two different initialization methods on the convergence process is analysed. The results show that the initialization method based on the one-dimensional isentropic theory effectively improves the convergence of the nozzle numerical model calculation process, accelerates the convergence speed and improves the calculation efficiency.