The adhesion of fine iron ore particles during fluidized bed reduction was studied using pressurized visible fluidized bed laboratory equipment.The results showed that the optimal operating parameters for pure hydroge...The adhesion of fine iron ore particles during fluidized bed reduction was studied using pressurized visible fluidized bed laboratory equipment.The results showed that the optimal operating parameters for pure hydrogen reduction under high pressure were reduction temperature of 1073 K,particle size of 0.18-0.66 mm,pure H_(2) linear velocity of 0.8 m/s,reduction pressure of 200 kPa,and reduction time of 50 min.When plastic particles were mixed into the fluidized bed,the optimal parameters were reduction temperature of 973 K,particle size of 0.18-0.66 mm,pure H_(2) linear velocity of 0.8 m/s,reduction pressure of 100 kPa,mass content of plastic particles of 8%,and reduction time of 65 min.The chemical reaction resistance is much higher than the inner diffusion resistance at the initial stage of the reaction,whereas,in later stage,the inner diffusion resistance exceeds the chemical reaction resistance.The contact area of iron atoms or iron whiskers gradually decreases with the increase in reduction pressure from 0.20 to 0.45 MPa,and the sticking trend gradually decreases.Adding plastic particles in the fluidized reduction process of fine iron ore can effectively inhibit the adhesion among fine iron ore particles.展开更多
Microplastics (MPs) have been an emerging concern due to their harmful effects on the ecosystem and are ubiquitous in various habitats, from marine to terrestrial environments. However, studies on the presence of MPs ...Microplastics (MPs) have been an emerging concern due to their harmful effects on the ecosystem and are ubiquitous in various habitats, from marine to terrestrial environments. However, studies on the presence of MPs in recreational areas are limited. One of the previous works has reported that urban recreational parks are considered “sinks” for plastic debris, including MPs. In this study, low-density MPs (LD-MPs) in soil samples collected from recreational parks of Al Ain, United Arab Emirates (UAE) were isolated by density flotation method. Results showed that these parks have varying levels of LD-MPs caused by various anthropogenic activities, such as sludge use and application of reclaimed water from wastewater treatment facilities in those areas. These plastic particles were isolated in 87% of the soil samples, with an average concentration of 1550 ± 340 MPs/kg. Predominantly, these comprised large LD-MPs (300 - 5000 μm), with red and blue being the most common colors. Fourier transform infrared (FTIR) spectroscopy identified possible synthetic polymers, including polyethylene and polypropylene. Additionally, a negative correlation was observed between LD-MP concentration and soil pH and moisture content, indicating potential adverse effects on soil health. These findings highlight the need for monitoring and managing microplastic pollution in urban recreational areas to mitigate its ecological impacts.展开更多
Floating MPs is a transboundary pollutant.Its transboundary nature and dynamics warrant deep know-how,not only on its transport and fate properties but also on understanding its mass change,which is a priority that ne...Floating MPs is a transboundary pollutant.Its transboundary nature and dynamics warrant deep know-how,not only on its transport and fate properties but also on understanding its mass change,which is a priority that needs relative addition for scientific dataset.This study highlights gravimetric analysis,another relevant technique to assess the accretion rate of pollutants,chemical risk and pollution load index on microplastics in the coastal waters of Limbe-Idenau,Cameroon.Sea-water samples were fished in five offshore distances in three distinct depth points in five purposive beaches on line transects.9 samples/beach with 45/season amounting to 90 bottled water samples and each collected sample were stored in 1 L glass bottle for further analysis.Systematic sample filtration,content weighing and reweighing after oven drying,and plastic mass calculation were done,aided by 4X magnification for plastic characterisation.178 MPs particles were identified with five unique particle weighs of 0.0000 g(150/0.0015 g),0.001 g(20/0.02 g),0.002 g(1/0.002 g),0.003 g(5/0.015 g)and 0.011 g(2/0.022 g)weighing 0.605 g.The most frequently observed plastic was the 0.0000 g weighed particle with physical appearance of RWPP>IWPP>OWPP in all the sampled seawater.In terms of weighs MPs analysis,the dominant beach,offshore distance,size ranged,abundance/season and physical outlook parameters in particle/number were recorded as follows:LBD 1(29.2%),5 m offshore distance(59.6%),1-1.5 m size ranged(55%)with mean size detection limits of 0.2 cm and dry season(77.5%).Lastly,the plastic physical outlook revealed that old weathered plastic particle,OWPP(51.1%)was dominant with large plastic mass loss experienced more during the rainy season.0.011 g weight plastic showed the highest average mass loss/particle(17.2%).Evidence from this study has reaffirmed that mass gained by certain weightless plastic indicates their long-time existence,knowledge of distance from sourced and fragmenting capacity within the marine environment.Both CF(2.71)and PLI(1.47)show a level II risk factor meanwhile the RQ value indicates a low rate potential of risk of degrees of injuries or damages to both marine organisms and beach users which requires urgent environmental management and pollution control strategies.展开更多
Understanding the fate and toxicity of microplastics(MPs,<5 mm plastic particles)is limited by quantification methods.This paper summarizes the methods in use and presents new ones.First,sampling and pretreatment p...Understanding the fate and toxicity of microplastics(MPs,<5 mm plastic particles)is limited by quantification methods.This paper summarizes the methods in use and presents new ones.First,sampling and pretreatment processes ofMPs,including sample collection,digestion,density separation,and quality control are reviewed.Then the promising and convenient staining procedures and quantification methods for MPs using fluorescence dyes are reviewed.The factors that influence the staining of MPs,including their physicochemical properties,are summarized to provide an optimal operation procedure.In general,the digestion step is crucial to eliminate natural organic matter(NOM)to avoid interference in quantification.Chloroform was reported to be the most appropriate solvent,and 10–20μg/mL are recommended as optimal dye concentrations.In addition,a heating and cooling procedure is recommended to maintain the fluorescence intensity of MPs for two months.After staining,a fluorescence microscope is usually used to characterize the morphology,mass,or number of MPs,but compositional analysis cannot be determined with it.These fluorescence staining methods have been implemented to study MP abundance,transport,and toxicity and have been combined with other chemical characterization techniques,such as Fourier transform infrared spectroscopy and Raman spectroscopy.More studies are needed to focus on the synthesis of novel dyes to avoid NOM’s interference.They need to be combined with other spectroscopic techniques to characterize plastic composition and to develop image-analysis methods.The stability of stained MPs needs to be improved.展开更多
基金the National Natural Science Foundation of China(No.51974001)the University outstanding young talents funding program(No.gxyq2019016).
文摘The adhesion of fine iron ore particles during fluidized bed reduction was studied using pressurized visible fluidized bed laboratory equipment.The results showed that the optimal operating parameters for pure hydrogen reduction under high pressure were reduction temperature of 1073 K,particle size of 0.18-0.66 mm,pure H_(2) linear velocity of 0.8 m/s,reduction pressure of 200 kPa,and reduction time of 50 min.When plastic particles were mixed into the fluidized bed,the optimal parameters were reduction temperature of 973 K,particle size of 0.18-0.66 mm,pure H_(2) linear velocity of 0.8 m/s,reduction pressure of 100 kPa,mass content of plastic particles of 8%,and reduction time of 65 min.The chemical reaction resistance is much higher than the inner diffusion resistance at the initial stage of the reaction,whereas,in later stage,the inner diffusion resistance exceeds the chemical reaction resistance.The contact area of iron atoms or iron whiskers gradually decreases with the increase in reduction pressure from 0.20 to 0.45 MPa,and the sticking trend gradually decreases.Adding plastic particles in the fluidized reduction process of fine iron ore can effectively inhibit the adhesion among fine iron ore particles.
文摘Microplastics (MPs) have been an emerging concern due to their harmful effects on the ecosystem and are ubiquitous in various habitats, from marine to terrestrial environments. However, studies on the presence of MPs in recreational areas are limited. One of the previous works has reported that urban recreational parks are considered “sinks” for plastic debris, including MPs. In this study, low-density MPs (LD-MPs) in soil samples collected from recreational parks of Al Ain, United Arab Emirates (UAE) were isolated by density flotation method. Results showed that these parks have varying levels of LD-MPs caused by various anthropogenic activities, such as sludge use and application of reclaimed water from wastewater treatment facilities in those areas. These plastic particles were isolated in 87% of the soil samples, with an average concentration of 1550 ± 340 MPs/kg. Predominantly, these comprised large LD-MPs (300 - 5000 μm), with red and blue being the most common colors. Fourier transform infrared (FTIR) spectroscopy identified possible synthetic polymers, including polyethylene and polypropylene. Additionally, a negative correlation was observed between LD-MP concentration and soil pH and moisture content, indicating potential adverse effects on soil health. These findings highlight the need for monitoring and managing microplastic pollution in urban recreational areas to mitigate its ecological impacts.
文摘Floating MPs is a transboundary pollutant.Its transboundary nature and dynamics warrant deep know-how,not only on its transport and fate properties but also on understanding its mass change,which is a priority that needs relative addition for scientific dataset.This study highlights gravimetric analysis,another relevant technique to assess the accretion rate of pollutants,chemical risk and pollution load index on microplastics in the coastal waters of Limbe-Idenau,Cameroon.Sea-water samples were fished in five offshore distances in three distinct depth points in five purposive beaches on line transects.9 samples/beach with 45/season amounting to 90 bottled water samples and each collected sample were stored in 1 L glass bottle for further analysis.Systematic sample filtration,content weighing and reweighing after oven drying,and plastic mass calculation were done,aided by 4X magnification for plastic characterisation.178 MPs particles were identified with five unique particle weighs of 0.0000 g(150/0.0015 g),0.001 g(20/0.02 g),0.002 g(1/0.002 g),0.003 g(5/0.015 g)and 0.011 g(2/0.022 g)weighing 0.605 g.The most frequently observed plastic was the 0.0000 g weighed particle with physical appearance of RWPP>IWPP>OWPP in all the sampled seawater.In terms of weighs MPs analysis,the dominant beach,offshore distance,size ranged,abundance/season and physical outlook parameters in particle/number were recorded as follows:LBD 1(29.2%),5 m offshore distance(59.6%),1-1.5 m size ranged(55%)with mean size detection limits of 0.2 cm and dry season(77.5%).Lastly,the plastic physical outlook revealed that old weathered plastic particle,OWPP(51.1%)was dominant with large plastic mass loss experienced more during the rainy season.0.011 g weight plastic showed the highest average mass loss/particle(17.2%).Evidence from this study has reaffirmed that mass gained by certain weightless plastic indicates their long-time existence,knowledge of distance from sourced and fragmenting capacity within the marine environment.Both CF(2.71)and PLI(1.47)show a level II risk factor meanwhile the RQ value indicates a low rate potential of risk of degrees of injuries or damages to both marine organisms and beach users which requires urgent environmental management and pollution control strategies.
基金This study was supported by the National Key R&D Program of China(Grant No.2017YFA0605001)the National Natural Science Foundation of China(Grant Nos.52170024,21677015 and 22006031)+1 种基金the Natural Science Foundation of Hebei Province(No.B2019204315)the Sponsored Research Overhead Fund(Grant No.472120)from Kansas State University.
文摘Understanding the fate and toxicity of microplastics(MPs,<5 mm plastic particles)is limited by quantification methods.This paper summarizes the methods in use and presents new ones.First,sampling and pretreatment processes ofMPs,including sample collection,digestion,density separation,and quality control are reviewed.Then the promising and convenient staining procedures and quantification methods for MPs using fluorescence dyes are reviewed.The factors that influence the staining of MPs,including their physicochemical properties,are summarized to provide an optimal operation procedure.In general,the digestion step is crucial to eliminate natural organic matter(NOM)to avoid interference in quantification.Chloroform was reported to be the most appropriate solvent,and 10–20μg/mL are recommended as optimal dye concentrations.In addition,a heating and cooling procedure is recommended to maintain the fluorescence intensity of MPs for two months.After staining,a fluorescence microscope is usually used to characterize the morphology,mass,or number of MPs,but compositional analysis cannot be determined with it.These fluorescence staining methods have been implemented to study MP abundance,transport,and toxicity and have been combined with other chemical characterization techniques,such as Fourier transform infrared spectroscopy and Raman spectroscopy.More studies are needed to focus on the synthesis of novel dyes to avoid NOM’s interference.They need to be combined with other spectroscopic techniques to characterize plastic composition and to develop image-analysis methods.The stability of stained MPs needs to be improved.
