The presence of ethanol has an adverse effect on foam spreading,and ethanol fire is difficult to extinguish with aqueous fire-fighting foams.Thus,it is necessary to explore the foam formulation suitable for ethanol fu...The presence of ethanol has an adverse effect on foam spreading,and ethanol fire is difficult to extinguish with aqueous fire-fighting foams.Thus,it is necessary to explore the foam formulation suitable for ethanol fuels and study the spreading behavior of foam over ethanol surface.In the current work,stable foams based on hydrocarbon surfactant(SDS),fluorocarbon surfactant(FC1157),and polymers(XG)were prepared by using the compressed-air foam system.The spreading behaviors of foam on polar ethanol and non-polar heptane surface were observed and compared.Furthermore,the effects of stabilizer concentrations,foam flow rates and expansion ratios on foam spreading performance were investigated,respectively.The results indicate that aqueous SDS foam can spread on the heptane layer continuously,but it is difficult to cover the ethanol surface.The addition of XG and FC1157 can synergistically improve the spreading performance of aqueous foam over ethanol.Depending on stabilizer concentrations,there are remarkable differences in foam spreading behaviors.Besides,different foam application parameters including expansion ratios and foam flow rates significantly affect the foam spreading rate,despite the same foam formulation.The research methods and results guide the optimal design of foam formulations as well as the practical application of aqueous foam for ethanol fire extinguishment.展开更多
Discharging untreated oily wastewater into the environment disrupts the ecological balance,which is a global problem that requires urgent solutions.Superhydrophilic and superoleophilic fibrous medium(FM)effectively se...Discharging untreated oily wastewater into the environment disrupts the ecological balance,which is a global problem that requires urgent solutions.Superhydrophilic and superoleophilic fibrous medium(FM)effectively separated oil–water emulsion as it was hydrophobic underwater.But its separation efficiencies(SEs)first increased to 98.9%,then dropped to 97.6%in 10 min because of oil-fouling.To tackle this problem,FM deposited with 0%–10%silica nanoparticle(NPsFMs),then coated by fluorocarbon polymer(X-[CH_(2)CH_(2)O]nCH_(2)CH_(2)O-Y-NH-COOCH_(2)C4F9)(FCNPs FMs),was used to enhance its roughness and regulate its initial wettability to improve the anti-fouling property.FCFM and FCNPs FMs were hydrophobic and oleophobic in air and oleophobic underwater.Their water contact angles,oil contact angles and oil contact angles were 115.3°–121.1°,128.8°–136.5°,and 131.6°–136.7°,respectively,meeting the requirement of 90°–140°for coalescence separation.FCNPs FM-5 had the best separation performance with a constant value of 99.8%in 10 min,while that of FCNPs FM-10 slightly decreased to 99.5%.Theoretical released droplet(TRD)diameter,calculated by the square root of the product of pore radius and fiber diameter,was used for the evaluation of coalescence performance.Analyzed by two ideal models,TRD diameter and fiber diameter showed a parabola type relationship,proving that the separation efficiency was a collaborative work of wettability,pore size and fiber diameter.Also,it explained the SEs reduction from FCNPs FM-5 to FCNPs FM-10 was revelent to the three parameters.Moreover,FCNPsFMs effectively separated emulsions stabilized by cationic surfactant CTAB(SEs:97.3%–98.4%)and anionic surfactant SDBS(SEs:91.3%–93.4%).But they had an adverse effect on nonionic surfactant Tween-80 emulsion separation(SEs:94.0%–71.76%).Emulsions made by diverse oils can be effectively separated:octane(SEs:99.4%–100%),rapeseed oil(SEs:97.3%–98.8%),and diesel(SEs:95.2%–97.0%).These findings provide new insights for desig展开更多
基金supported by the National Key Research and Development Program of China(2016YFB1200505)Jiangsu Key Research and Development Plan Project(BE2020663)the Anhui Key Research and Development Plan Project(No.1804a0802202)。
文摘The presence of ethanol has an adverse effect on foam spreading,and ethanol fire is difficult to extinguish with aqueous fire-fighting foams.Thus,it is necessary to explore the foam formulation suitable for ethanol fuels and study the spreading behavior of foam over ethanol surface.In the current work,stable foams based on hydrocarbon surfactant(SDS),fluorocarbon surfactant(FC1157),and polymers(XG)were prepared by using the compressed-air foam system.The spreading behaviors of foam on polar ethanol and non-polar heptane surface were observed and compared.Furthermore,the effects of stabilizer concentrations,foam flow rates and expansion ratios on foam spreading performance were investigated,respectively.The results indicate that aqueous SDS foam can spread on the heptane layer continuously,but it is difficult to cover the ethanol surface.The addition of XG and FC1157 can synergistically improve the spreading performance of aqueous foam over ethanol.Depending on stabilizer concentrations,there are remarkable differences in foam spreading behaviors.Besides,different foam application parameters including expansion ratios and foam flow rates significantly affect the foam spreading rate,despite the same foam formulation.The research methods and results guide the optimal design of foam formulations as well as the practical application of aqueous foam for ethanol fire extinguishment.
基金supported by the National Key Research and Development Program of China under the contract number of 2017YFB0308000Program of Innovation Academy for Green Manufacture,CAS(IAGM2020C04)+1 种基金the State Key Laboratory of Heavy Oil Processing(SKLOP201903001)Key Research and Development Program of Hebei Province,China(20374001D)。
文摘Discharging untreated oily wastewater into the environment disrupts the ecological balance,which is a global problem that requires urgent solutions.Superhydrophilic and superoleophilic fibrous medium(FM)effectively separated oil–water emulsion as it was hydrophobic underwater.But its separation efficiencies(SEs)first increased to 98.9%,then dropped to 97.6%in 10 min because of oil-fouling.To tackle this problem,FM deposited with 0%–10%silica nanoparticle(NPsFMs),then coated by fluorocarbon polymer(X-[CH_(2)CH_(2)O]nCH_(2)CH_(2)O-Y-NH-COOCH_(2)C4F9)(FCNPs FMs),was used to enhance its roughness and regulate its initial wettability to improve the anti-fouling property.FCFM and FCNPs FMs were hydrophobic and oleophobic in air and oleophobic underwater.Their water contact angles,oil contact angles and oil contact angles were 115.3°–121.1°,128.8°–136.5°,and 131.6°–136.7°,respectively,meeting the requirement of 90°–140°for coalescence separation.FCNPs FM-5 had the best separation performance with a constant value of 99.8%in 10 min,while that of FCNPs FM-10 slightly decreased to 99.5%.Theoretical released droplet(TRD)diameter,calculated by the square root of the product of pore radius and fiber diameter,was used for the evaluation of coalescence performance.Analyzed by two ideal models,TRD diameter and fiber diameter showed a parabola type relationship,proving that the separation efficiency was a collaborative work of wettability,pore size and fiber diameter.Also,it explained the SEs reduction from FCNPs FM-5 to FCNPs FM-10 was revelent to the three parameters.Moreover,FCNPsFMs effectively separated emulsions stabilized by cationic surfactant CTAB(SEs:97.3%–98.4%)and anionic surfactant SDBS(SEs:91.3%–93.4%).But they had an adverse effect on nonionic surfactant Tween-80 emulsion separation(SEs:94.0%–71.76%).Emulsions made by diverse oils can be effectively separated:octane(SEs:99.4%–100%),rapeseed oil(SEs:97.3%–98.8%),and diesel(SEs:95.2%–97.0%).These findings provide new insights for desig
