Soil contamination by metals is a worldwide environmental problem. Electrokinetic extraction is a promising technology for in-situ remediation of contaminated soils of low hydraulic permeability. However, the extracti...Soil contamination by metals is a worldwide environmental problem. Electrokinetic extraction is a promising technology for in-situ remediation of contaminated soils of low hydraulic permeability. However, the extraction of metals is usually hindered by the high buffer capacity of natural soils. Organophosphonates are strong metal chelates as ethylenediaminetetraacetic acid(EDTA) which has been widely studied in the enhancement of electrokinetic remediation. In this study, batch desorption experiments and bench-scale electrokinetic extraction experiments were carried out to study the effect of two organophosphonates, i.e.,(nitrilotrimethylene)triphosphonate(NTMP) &(ethylenedinitrilo)-tetramethylenephosphonate(EDTMP), on the extraction of cadmium from a natural clay in comparison with EDTA. Results of the batch desorption experiments showed that more than 75% of the sorbed cadmium could be dissolved into solution using 0.1 mol·L^(-1) organophosphonates or EDTA in the wide p H range of 1–11. Results of the electrokinetic extraction experiments showed that the cadmium spiked in the specimen migrated towards the anode with the enhancement of NTMP,EDTMP, and EDTA under a constant voltage gradient of approximately 1.0 V·cm-1. Although cadmium mobilization enhanced by EDTA was more efficient than that by the organophosphonates, accumulation of cadmium was observed in the vicinity of the anode. The average removal efficiencies of cadmium from the soil after approximately 5 days of electrokinetic extraction enhanced by 0.1 mol·L-1 NTMP(22.8%) and EDTMP(22.4%) were higher than that by 0.1 mol·L^(-1) EDTA(15.1%).展开更多
The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative...The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the CO_(2) composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components (Q_(1), Q_(2), and Q_(3)) of the coal seam. The results show that in-situ total gas content (Q_(T)) ranges from 9.48 m^(3)/t for the A2 section to 14.80 m^(3)/t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q_(2) demonstrates the highest contribution to Q_(T), ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes CO_(2) sorption behavior, with ft coefcients (R^(2)) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content (Q_(3)) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q_(1) and Q_(2) gas contents, lower sorption hysteresis, and reduced coal toughness f value. The insights derived from the study can contribute to the development of efective gas management strategies and enhance the safety and efciency of coal mining operations.展开更多
在煤层气开采过程中使用的入井流体都添加了不同类型的表面活性剂,不仅对煤储层的表面性质产生影响,还影响煤层气的解吸能力。因此,室内使用两种不同的煤样以及不同的表面活性剂开展了表面张力和接触角以及煤层气常压、变压解吸实验评价...在煤层气开采过程中使用的入井流体都添加了不同类型的表面活性剂,不仅对煤储层的表面性质产生影响,还影响煤层气的解吸能力。因此,室内使用两种不同的煤样以及不同的表面活性剂开展了表面张力和接触角以及煤层气常压、变压解吸实验评价,结果表明:表面活性剂的加入使溶液表面张力明显降低,其中复配表面活性剂FP-GA的效果最好,质量浓度为0.5%时能使表面张力降低至22.6 m N/m;阴离子表面活性剂AS-02降低煤样表面接触角的效果最好,能使硬煤和软煤表面的接触角分别降低至9°和12°;使用表面活性剂处理后硬煤和软煤的常压、变压解吸量均明显增大,其中复配表面活性剂FP-GA使两种煤样常压和变压解吸量的提升幅度最大,能显著提高煤层气的解吸能力。这主要是表面活性剂可以通过降低表面张力和改变煤岩表面润湿性的方式来降低煤层气解吸时的毛细管阻力,从而起到增大煤层气解吸量的效果,为煤层气开发过程合理使用表面活性剂提供一定的借鉴。展开更多
Dry sediments were collected from one roof and two roads in the central area of Beijing. The sediments were dry and wet sieved. The concentrations of total phosphorus (TP) and heavy metals were analyzed. The highest m...Dry sediments were collected from one roof and two roads in the central area of Beijing. The sediments were dry and wet sieved. The concentrations of total phosphorus (TP) and heavy metals were analyzed. The highest mass proportion of the dry sediments from the roads were between 125 and 300 μm in diameter, while the roof sediments were much smaller, with 75% of the total sediment mass between 40 and 74 μm in diameter. The concentrations of TP and heavy metals in the roof sediments were much higher than in the road sediments. The concentrations of the six heavy metals investigated had a similar order for all three sampling sites, with the Zn concentration always being the highest, followed by the Mn concentration, and the Ni concentration was always the lowest. After wet sieving, 76.9% to 91% of the TP in the sediments from the three sites remained in undesorbable particulate form, and 68.9% to 97% of the heavy metals were present in undesorbable particulate form. The concentrations of undesorbed heavy metals in the roof sediments tended to increase with increasing sediment size, but a similar trend was not found in the road sediments. This study shows that more attention should be given to the particulate matter in stormwater runoff, as reducing the amount of particulates will improve the efficiency of pollution control measures.展开更多
基金Supported by the National Natural Science Foundation of China(41201303)Shandong Province Natural Science Foundation,China(ZR2017QEE016)+1 种基金the Fundamental Research for the Central Universities(14CX02191A,17CX02075)State Key Laboratory of Pollution Control and Resource Reuse Foundation(PCRRF13023)
文摘Soil contamination by metals is a worldwide environmental problem. Electrokinetic extraction is a promising technology for in-situ remediation of contaminated soils of low hydraulic permeability. However, the extraction of metals is usually hindered by the high buffer capacity of natural soils. Organophosphonates are strong metal chelates as ethylenediaminetetraacetic acid(EDTA) which has been widely studied in the enhancement of electrokinetic remediation. In this study, batch desorption experiments and bench-scale electrokinetic extraction experiments were carried out to study the effect of two organophosphonates, i.e.,(nitrilotrimethylene)triphosphonate(NTMP) &(ethylenedinitrilo)-tetramethylenephosphonate(EDTMP), on the extraction of cadmium from a natural clay in comparison with EDTA. Results of the batch desorption experiments showed that more than 75% of the sorbed cadmium could be dissolved into solution using 0.1 mol·L^(-1) organophosphonates or EDTA in the wide p H range of 1–11. Results of the electrokinetic extraction experiments showed that the cadmium spiked in the specimen migrated towards the anode with the enhancement of NTMP,EDTMP, and EDTA under a constant voltage gradient of approximately 1.0 V·cm-1. Although cadmium mobilization enhanced by EDTA was more efficient than that by the organophosphonates, accumulation of cadmium was observed in the vicinity of the anode. The average removal efficiencies of cadmium from the soil after approximately 5 days of electrokinetic extraction enhanced by 0.1 mol·L-1 NTMP(22.8%) and EDTMP(22.4%) were higher than that by 0.1 mol·L^(-1) EDTA(15.1%).
基金supported by China Scholarship Council(202006430006)the International Postgraduate Tuition Award(IPTA)of the University of Wollongongthe research funding provided by the Mine A,ACARP Project C35015 and Coal Services Health and Safety Trust.
文摘The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the CO_(2) composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components (Q_(1), Q_(2), and Q_(3)) of the coal seam. The results show that in-situ total gas content (Q_(T)) ranges from 9.48 m^(3)/t for the A2 section to 14.80 m^(3)/t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q_(2) demonstrates the highest contribution to Q_(T), ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes CO_(2) sorption behavior, with ft coefcients (R^(2)) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content (Q_(3)) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q_(1) and Q_(2) gas contents, lower sorption hysteresis, and reduced coal toughness f value. The insights derived from the study can contribute to the development of efective gas management strategies and enhance the safety and efciency of coal mining operations.
文摘在煤层气开采过程中使用的入井流体都添加了不同类型的表面活性剂,不仅对煤储层的表面性质产生影响,还影响煤层气的解吸能力。因此,室内使用两种不同的煤样以及不同的表面活性剂开展了表面张力和接触角以及煤层气常压、变压解吸实验评价,结果表明:表面活性剂的加入使溶液表面张力明显降低,其中复配表面活性剂FP-GA的效果最好,质量浓度为0.5%时能使表面张力降低至22.6 m N/m;阴离子表面活性剂AS-02降低煤样表面接触角的效果最好,能使硬煤和软煤表面的接触角分别降低至9°和12°;使用表面活性剂处理后硬煤和软煤的常压、变压解吸量均明显增大,其中复配表面活性剂FP-GA使两种煤样常压和变压解吸量的提升幅度最大,能显著提高煤层气的解吸能力。这主要是表面活性剂可以通过降低表面张力和改变煤岩表面润湿性的方式来降低煤层气解吸时的毛细管阻力,从而起到增大煤层气解吸量的效果,为煤层气开发过程合理使用表面活性剂提供一定的借鉴。
基金supported by the National Basic Research Program of China (2006CB403403)the National Natural Science Foundation for Innovative Research Group (51121003)the National Natural Science Foundation of China (51278054)
文摘Dry sediments were collected from one roof and two roads in the central area of Beijing. The sediments were dry and wet sieved. The concentrations of total phosphorus (TP) and heavy metals were analyzed. The highest mass proportion of the dry sediments from the roads were between 125 and 300 μm in diameter, while the roof sediments were much smaller, with 75% of the total sediment mass between 40 and 74 μm in diameter. The concentrations of TP and heavy metals in the roof sediments were much higher than in the road sediments. The concentrations of the six heavy metals investigated had a similar order for all three sampling sites, with the Zn concentration always being the highest, followed by the Mn concentration, and the Ni concentration was always the lowest. After wet sieving, 76.9% to 91% of the TP in the sediments from the three sites remained in undesorbable particulate form, and 68.9% to 97% of the heavy metals were present in undesorbable particulate form. The concentrations of undesorbed heavy metals in the roof sediments tended to increase with increasing sediment size, but a similar trend was not found in the road sediments. This study shows that more attention should be given to the particulate matter in stormwater runoff, as reducing the amount of particulates will improve the efficiency of pollution control measures.
