The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black sha...The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black shale from four wells in the Upper Yangtze Platform, and their TOC, mineralogical composition and pore characterization were investigated. Low pressure N2 and CO2 adsorption were conducted at 77.35 K and 273.15 K, respectively, and the pore structures were characterized by modified Brunauer-Emmett-Teller （BET）, Dubinin-Radushkevich （DR）, t-plot, Barrett- Joyner-Halenda （BJH） and density functional theory （DFT） methods and then the relationship between pore structure and shale gas sorption capacity was discussed. The results indicate that （1） The Lower Silurian shale has high TOC content of 0.92%~96%, high quartz content of 30.6%-69.5%, and high clays content of 24.1%-51.2%. The total specific surface area varies from 7.56 m^2/g to 25.86 m^2/g. Both the total specific surface area and quartz content are positively associated with the TOC content. （2） Shale samples with higher TOC content have more micropores, which results in more complex nanopore structure. Micropore volumes/surface areas and non-micropore surface areas all increase with the increasing TOC content. （3） A combination of N2 and CO2 adsorption provides the most suitable detection range （~0.3-60 nm） and has high reliability and accuracy for nanopore structure characterization. （4） The TOC content is the key factor to control the gas sorption capacity of the Lower Silurian shale in the Upper Yangtze Platform.展开更多
Oil spills in the sea have caused many serious environmental problems worldwide. In this study, carbon nanotube （CNT） sponges were used to cleanup oil slicks on sea waters. This method was compared with two traditio...Oil spills in the sea have caused many serious environmental problems worldwide. In this study, carbon nanotube （CNT） sponges were used to cleanup oil slicks on sea waters. This method was compared with two traditional representative sorbents, including polypropylene fiber fabric and woolen felt. The CNT sponges had a larger oil sorption capacity than the other two sorbents. The maximum oil sorption capacity （Qm） of the CNT sponge was 92.30 g/g, which was 12 to 13.5 times larger than the Qm of the other two sorbents （the Qm of the polypropylene fiber fabric and woolen felt were 7.45 and 6.74 g/g, respectively）. In addition, unlike the other two sorbents, the CNT sponge was super- hydrophobic and did not adsorb any water during oil spill cleanup. CNT sponges are potentially very useful for cleaning up oil spills from sea water.展开更多
The sorption capacity and affinity of biochar for metals are both important attributes that determine biochar’s suitability as a soil amendment for contaminant mitigation,yet few analyses have considered both charact...The sorption capacity and affinity of biochar for metals are both important attributes that determine biochar’s suitability as a soil amendment for contaminant mitigation,yet few analyses have considered both characteristics simultaneously.We present a systematic review of literature published between 2010 and 2018 to test the hypothesis that sorption capacity and affinity are affected by biochar properties,attributes of the metal contaminant,and experimental conditions,in that order.We used random forest(RF)and multi-objective optimization to analyze data of 559 individual Langmuir adsorption isotherms extracted from 133 studies covering the sorption capacity(C_(max))and affinity(K_(L))of biochar for 17 different metals,elabo-rated from six different feedstock classes,three different types of feedstock pretreatment,and five types of post-pyrolysis treatment.Highest sorption values were obtained for Pb(II),Cr(IV),and Cd(II).The feedstock used was the key determinant influencing biochar’s capacity and affinity to sorb metal contaminants(first and fourth most important variable in RF mod-els for C_(max) and K_(L),respectively)with best results obtained for biochar elaborated from nutrient-dense feedstocks(animal biowaste,sludge,and manure).Biochars that had both high sorption capacity and affinity were the result of a longer dura-tion of pyrolysis;they had lower C and higher N and O content,as well as lower C/N and higher O/C and H/C ratios,higher pore volumes and higher pH.Applying some form of pretreatment was better than none,whereas chemical modification was the best of the post-treatment methods analyzed.This review demonstrates clearly that multiple parameters during the preparation process influence the effectiveness of biochar to immobilize metal contaminants.Future research that focuses on mechanisms and the underlying factors for the correlations observed should allow the development of biochar formulations that are even more effective at immobilizing metal contaminants in soils and sediments.展开更多
基金the financial support of the National Science and Technology Major Project(No.2016ZX05034-001)National Natural Science Foundation of China(No.41472112)
文摘The pores in shales are mainly of nanometer-scale, and their pore size distribution is very important for the preservation and exploitation of shale gas. This study focused on the organic-rich Lower Silurian black shale from four wells in the Upper Yangtze Platform, and their TOC, mineralogical composition and pore characterization were investigated. Low pressure N2 and CO2 adsorption were conducted at 77.35 K and 273.15 K, respectively, and the pore structures were characterized by modified Brunauer-Emmett-Teller （BET）, Dubinin-Radushkevich （DR）, t-plot, Barrett- Joyner-Halenda （BJH） and density functional theory （DFT） methods and then the relationship between pore structure and shale gas sorption capacity was discussed. The results indicate that （1） The Lower Silurian shale has high TOC content of 0.92%~96%, high quartz content of 30.6%-69.5%, and high clays content of 24.1%-51.2%. The total specific surface area varies from 7.56 m^2/g to 25.86 m^2/g. Both the total specific surface area and quartz content are positively associated with the TOC content. （2） Shale samples with higher TOC content have more micropores, which results in more complex nanopore structure. Micropore volumes/surface areas and non-micropore surface areas all increase with the increasing TOC content. （3） A combination of N2 and CO2 adsorption provides the most suitable detection range （~0.3-60 nm） and has high reliability and accuracy for nanopore structure characterization. （4） The TOC content is the key factor to control the gas sorption capacity of the Lower Silurian shale in the Upper Yangtze Platform.
文摘Oil spills in the sea have caused many serious environmental problems worldwide. In this study, carbon nanotube （CNT） sponges were used to cleanup oil slicks on sea waters. This method was compared with two traditional representative sorbents, including polypropylene fiber fabric and woolen felt. The CNT sponges had a larger oil sorption capacity than the other two sorbents. The maximum oil sorption capacity （Qm） of the CNT sponge was 92.30 g/g, which was 12 to 13.5 times larger than the Qm of the other two sorbents （the Qm of the polypropylene fiber fabric and woolen felt were 7.45 and 6.74 g/g, respectively）. In addition, unlike the other two sorbents, the CNT sponge was super- hydrophobic and did not adsorb any water during oil spill cleanup. CNT sponges are potentially very useful for cleaning up oil spills from sea water.
文摘The sorption capacity and affinity of biochar for metals are both important attributes that determine biochar’s suitability as a soil amendment for contaminant mitigation,yet few analyses have considered both characteristics simultaneously.We present a systematic review of literature published between 2010 and 2018 to test the hypothesis that sorption capacity and affinity are affected by biochar properties,attributes of the metal contaminant,and experimental conditions,in that order.We used random forest(RF)and multi-objective optimization to analyze data of 559 individual Langmuir adsorption isotherms extracted from 133 studies covering the sorption capacity(C_(max))and affinity(K_(L))of biochar for 17 different metals,elabo-rated from six different feedstock classes,three different types of feedstock pretreatment,and five types of post-pyrolysis treatment.Highest sorption values were obtained for Pb(II),Cr(IV),and Cd(II).The feedstock used was the key determinant influencing biochar’s capacity and affinity to sorb metal contaminants(first and fourth most important variable in RF mod-els for C_(max) and K_(L),respectively)with best results obtained for biochar elaborated from nutrient-dense feedstocks(animal biowaste,sludge,and manure).Biochars that had both high sorption capacity and affinity were the result of a longer dura-tion of pyrolysis;they had lower C and higher N and O content,as well as lower C/N and higher O/C and H/C ratios,higher pore volumes and higher pH.Applying some form of pretreatment was better than none,whereas chemical modification was the best of the post-treatment methods analyzed.This review demonstrates clearly that multiple parameters during the preparation process influence the effectiveness of biochar to immobilize metal contaminants.Future research that focuses on mechanisms and the underlying factors for the correlations observed should allow the development of biochar formulations that are even more effective at immobilizing metal contaminants in soils and sediments.
