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Spilled oil frequently reaches the shorelines and affects coastal biota and communities. The application of surface washing agents is an important shoreline cleanup technique that can help remove stranded oil from substrate surfaces with the advantages of high removal efficiency, low toxicity, and strong economic viability. In this study, the investigation into the oil removal from contaminated sand using a surface washing agent under variable environmental conditions was conducted. A preliminary test was conducted to obtain the optimal combination of operating factors of surface washing agent-to-oil ratio (SOR) 2:1, mixing speed 150 rpm, and mixing time 30 min. The results of single-factor experiments showed that high temperature and humic acid concentration of flush water contributed to the performance of a surface washing agent, while salinity and kaolinite concentration could inhibit its performance. The factorial analysis revealed the main effects of temperature and salinity, and the interactive effects of temperature and salinity as well as salinity and humic acid concentration that were significant to the washing efficiency of the surface washing agent. In addition, the comprehensive assessment of a surface washing agent from the aspects of toxicity, detergency, dispersion properties, and field trials was conducted. The results have significant implications for future application of surface washing agents in the shoreline cleanup., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Inland oil spill accidents pose a negative impact on the health of the soil ecological system and human beings. The oil infiltration process is the main behavior of spilled oil, and its infiltration is influenced by many environmental factors like root netting and rainfall. This study was conducted to investigate the impact of these two important factors on the infiltration process and reduce the pollution of inland oil spill accidents. For root nettings, they can change the soil permeability and pore volume distribution, which are important in liquid infiltration, while rainwater can change the soil water content, thereby affecting the pressure, capillary force, and buoyancy force of spilled oil in the infiltration process. In the present study, these two unique factors of oil infiltration were investigated by detecting the infiltration front head and concentration distribution of spilled oil in soil layers with various root netting structures as well as the rainfall modes. It is found that root netting and surface rainfall critically affect oil infiltration in soil. The nettings with a finer mesh size and denser plant roots show a more significant effect on the infiltration process, particularly when their pore size is smaller than that of the soil. The netting's position and soil particle size also play crucial roles, influencing where oil accumulates within soil layers. Rainfall timing and intensity further modify oil movement, with prior rainfall reducing infiltration, while subsequent rain can increase it. The findings can help better understand the transport of spilled oil transport and implement emergency response measures for inland oil spills. [ABSTRACT FROM AUTHOR]

Oil deposited on shoreline substrates has serious adverse effects on the coastal environment and can persist for a long time. In this study, a green and effective microemulsion (ME) derived from vegetable oil was developed as a washing fluid to remove stranded oil from beach sand. The pseudo-ternary phase diagrams of the castor oil/water (without or without NaCl)/Triton X-100/ethanol were constructed to determine ME regions, and they also demonstrated that the phase behaviors of ME systems were almost independent of salinity. ME-A and ME-B exhibited high oil removal performance, low surfactant residues, and economic benefits, which were determined to be the W/O microstructure. Under optimal operation conditions, the oil removal efficiencies for both ME systems were 84.3 % and 86.8 %, respectively. Moreover, the reusability evaluation showed that the ME system still had over 70 % oil removal rates, even though it was used six times, implying its sustainability and reliability. [Display omitted] • Vegetable oil-based microemulsions were developed to remove stranded oil from sand. • The effectiveness of microemulsion systems can be up to 86 % for oil removal. • Microemulsions can easily diffuse and penetrate into the oil film on solid surface. • Microemulsions exhibited long-term stability which is beneficial for application. • The performance of microemulsions in oil removal was satisfactory after reuse. [ABSTRACT FROM AUTHOR]

It is well known that oil stranded on shoreline substrates can be difficult to remove and cause serious environmental effects. To address this issue, a calcium alginate-cellulose nanocrystal (CA-CNC)-based coating with a unique surface structure and superhydrophobic properties was developed to reduce the extent of shoreline oiling. The results of batch washing test showed that not only did the introduction of CNC not reduce the oil removal efficiency; it also improved the environmental stability of the coating to resist the effects associated with seawater immersion and erosion (especially in the case of 0.4 wt% of CNC). The oil-repellent performance of the coated gravels implied that both oscillation time and oil concentration had almost no effects on the amount of adhered oil. Assessment of oiling prevention based on the laboratory shoreline tank simulator proved the coated gravel performed very well as more oil floated and less oil remained on substrates and penetrated into the subsurface. Biotoxicity analysis showed that the coating powders reduced impacts on the toxicity of the oil to algae at low doses. There is a good potential for the use of this CA-CNC based coating technique to improve shoreline oil spill response. [Display omitted] • A calcium alginate-cellulose nanocrystal-based coating approach was developed. • The coated gravels showed good performance of oil removal and repellence. • The coating exhibited environmental stability in immersion and erosion of seawater. • The feasibility of using coating for oiling prevention was proved in tank tests. • Biotoxicity analysis revealed the coating alleviated the toxicity of oil to algae. [ABSTRACT FROM AUTHOR]