【作者】 张凯；

【导师】 张代钧；

【作者基本信息】 重庆大学 ， 环境科学与工程， 2019， 硕士

【摘要】 页岩气开发是我国重大能源发展战略。目前广泛采用的水力压裂开采技术会产生大量的返排水/产出水,其成分复杂且含有高盐分（包括铵盐和磷酸盐）,现有水处理技术难以处理。微生物脱盐电池（MDC）是本世纪初出现的一种可以同时去除有机物和脱盐的装置。针对MDC阴极通常使用贵金属催化剂的缺陷,本论文设计并制备金属杂多酸/炭黑替代铂催化剂,开展MDC去除有机物,并同时回收铵和磷酸盐的实验研究,为发展压裂返排水处理的替代技术提供参考。（1）制备新型H₃PMo₁₂O₄₀/炭黑（PMo/CB）材料作为氧还原反应（ORR）催化剂。利用XRD、XPS、FT-IR及BET等技术对催化剂结构和化学组成进行表征,结果表明PMo固载于炭黑,形成了特定的结构。利用LSV和旋转圆盘电极（RDE）评估了PMo/CB的电化学性能,结果表明PMo/CB的催化活性与PMo和CB的质量比有关。其中PMo与CB质量比为10%的样品（PMo/CB-10）具有最佳的ORR活性,并且PMo/CB-10在ORR过程中的电子转移数和转移机制与铂碳催化剂的基本一致。利用PMo/CB-10作为阴极催化剂构建空气阴极微生物燃料电池（MFC）,采用醋酸钠（CH₃COONa）配制高盐（10g/L NaCl）废水进行实验,结果表明PMo/CB-10-MFC产生的最大功率密度高达1195.1±41.7mW/m²,比Pt/C-MFC（984.2±62.2 mW/m²）高了21.4%;在连续四个月运行周期内,PMo/CB-10-MFC的功率密度持续高于Pt/C的功率密度,且一直保持较高的功率输出,表明PMo/CB-10作为MFC空气阴极的电催化剂能够保持长期稳定的ORR活性。（2）研究PMo/CB-MFC（PMo/CB-10-MFC）处理压裂返排水（以瓜胶,聚丙烯酰胺等为主要有机污染物）的性能。当返排水中NaCl浓度为10 g/L时,PMo/CB-MFC的输出功率密度为347.2±23.0mW/m²,较Pt/C-MFC（192.9±34.0mW/m²）高出44.4%,在反应器稳定运行10个循环中,PMo/CB-MFC平均COD去除率达71.2±2.4%较Pt/C-MFC（68.9±5.4%）高出3.2%;随着NaCl浓度的升高,PMo/CB-MFC的产电性能逐渐下降;当返排水中NaCl浓度为120g/L时,MFC的输出电压为0.32±0.1V,功率密度为67.4±26.0 mW/m²,COD的去除率为50.8±15.0%,表明MFC对高盐返排水具有较高的处理能力。（3）构建PMo/CB-MDC并优化其性能。实验结果表明,当外加电阻为5Ω时,PMo/CB-MDC和Pt/C-MDC输出电流最大分别可达9.0mA、8.0mA,并且随着阴极室与阳极室的循环流速的增加,体系出水COD去除率和脱盐效率不断增加,当流速为1.6mL/min时PMo/CB-MDC和Pt/C-MDC的COD去除率分别达到72.4%和69.8%,脱盐率分别为22.8%和21.9%,脱盐速率分别为190.0mg/h和188.0mg/h,所构建的MDC对返排水具有较高的COD去除并能够去除和回收部分盐分。（4）将模拟返排水的NaCl浓度从10g/L增至60g/L,设置PO₄^3-为100mg/L以及不同的NH₄⁺浓度（100mg/L、300 mg/L、600mg/L及1000mg/L）,研究了不同NH₄⁺浓度对COD去除、NH₄⁺和PO₄^3-去除和回收性能的影响。实验结果表明,当NH₄⁺浓度为300mg/L时NH₄⁺和PO₄^3-去除率达到最高（58.6±19.0%和75.8±32.0%）,其中NH₄⁺和PO₄^3-回收率分别为42.1%和59.1%,当NH₄⁺浓度为600mg/L时COD去除率达到最大（90.7±5.0%）。因此可说明较高的NH₄⁺浓度对电活性微生物代谢具有促进作用,利用MDC可以去除返排水中的COD并回收部分营养盐。更多还原

【Abstract】 Shale gas development is China’s major energy development strategy.The widely used hydraulic fracturing technology produces a large amount of flowback/produced water,which is complex in composition and contains high salinity（including ammonium salts and phosphates）,which is difficult to handle with existing water treatment technologies.Microbial desalination cell（MDC）is a device that emerged at the beginning of this century to remove both organic matter and desalination.In view of the defects of noble metal catalysts for MDC cathodes,this paper designs and prepares metal heteropolyacid/carbon black instead of platinum catalysts,carries out MDC removal of organic matter,and simultaneously recovers ammonium and phosphate experiments for the development of flowback water treatment.This experiment also provides a reference for the development of alternative technologies for flowback water treatment.（1）A novel H₃PMo₁₂O₄₀/carbon black（PMo/CB）material was prepared as an oxygen reduction reaction（ORR）catalyst.The structure and chemical composition of the catalyst were characterized by XRD,XPS,FT-IR and BET.The results showed that PMo was immobilized on carbon black and formed a specific structure.The electrochemical properties of PMo/CB were evaluated by LSV and rotating disk electrode（RDE）.The results show that the catalytic activity of PMo/CB is related to the mass ratio of PMo and CB.The sample with PMo and CB mass ratio of 10%（PMo/CB-10）has the best ORR activity,and the electron transfer number and transfer mechanism of PMo/CB-10 in the ORR process are basically the same as those of the platinum carbon catalyst.The air cathode microbial fuel cell（MFC）was constructed by using PMo/CB-10 as the cathode catalyst,and the high-salt（10 g/L NaCl）wastewater was prepared by using sodium acetate（CH₃COONa）.The results showed that the maximum power density of PMo/CB-10-MFC is 1195.1±41.7mW/m²,which is 21.4%higher than Pt/C-MFC（984.2±62.2 mW/m²）.The power density of PMo/CB-10-MFC continues for four consecutive months.Which is even higher than the power output of Pt/C,and always maintain a high power output,indicating that PMo/CB-10 as an MFC air-cathode electrocatalyst can maintain long-term stable ORR activity.（2）The performance of PMo/CB-MFC（PMo/CB-10-MFC）in the treatment of fracturing flowback water（with guar gum,polyacrylamide,etc.as the main organic pollutant）was studied.When the NaCl concentration in the flowback water is 10 g/L,the output power density of PMo/CB-MFC is 347.2±23.0 mW/m²,which is 44.4%higher than that of Pt/C-MFC（192.9±34.0 mW/m²）.In the 10 cycles of stable reactor operation,the average COD removal rate of PMo/CB-MFC is 71.2±2.4%higher than that of Pt/C-MFC（68.9±5.4%）.With the increase of NaCl concentration,the electricity production performance of PMo/CB-MFC gradually decreases.When the NaCl concentration is 120g/L in the flowback water,the output voltage of MFC is 0.32±0.1V,the power density is 67.4±26.0 mW/m²,the removal rate of COD was 50.8±15.0%,indicating that MFC has a high processing capacity for high salt flowback water.（3）The PMo/CB-MDC was constructed.Optimize MDC performance by changing applied resistance and circulating flow rate.The results show that when the applied resistance is 5Ω,the output currents of PMo/CB-MDC and Pt/C-MDC are up to 9.0mA and 8.0mA,respectively,and the system effluent increases with the circulating flow rate of the cathode and anode chambers.The COD removal rate and desalination efficiency increased continuously.When the flow rate was 1.6 mL/min,the COD removal rates of PMo/CB-MDC and Pt/C-MDC were 72.4%and 69.8%,respectively,and the salt rejection rates were 22.8%and 21.9%,respectively.The desalting rates were 190.0mg/h and 188.0 mg/h,respectively.The constructed MDC had higher COD removal and was able to remove and recover part of the salt in flowback water.（4）The NaCl concentration was increased to 60g/L,and PO₄^3-was set to 100mg/L and different NH₄⁺concentrations（100mg/L,300mg/L,600mg/L and 1000mg/L）in simulated flowback water.The effects of different NH₄⁺concentrations in the flowback water on COD removal,NH₄⁺and PO₄^3-removal and recovery performance were investigated.These results show that the NH₄⁺and PO₄^3-removal rates are the highest（58.6±19.0%and 75.8±32.0%）when the NH₄⁺concentration is 300 mg/L,and the NH₄⁺and PO₄^3-recovery rates are 42.1%and 59.1%,respectively.The COD removal rate reached the maximum（90.7±5.0%）at 600 mg/L.Therefore,it can be explained that the higher NH₄⁺concentration has a promoting effect on the metabolism of electroactive microorganisms,and the MDC can be used to remove COD and recover part of the nutrient salt in flowback water.更多还原