【作者】 徐静；

【导师】 张国权；

【作者基本信息】 大连理工大学 ， 环境科学与工程， 2018， 硕士

【摘要】 反渗透（RO）是一种借助于选择透过性膜的功能以压力差为推动力的膜分离技术。由于反渗透过程简单,能耗低,近20年来得到迅速发展。现已大规模应用于海水淡化、苦咸水脱盐和各行各业的废水终端处理,并与离子交换结合制取高纯水,其应用范围正在不断扩大,对环境保护和可持续发展都有着重要意义,对缺水地区具有巨大的经济效益。但是反渗透过程通常会产生大约三分之一的浓水,该水质由于含有较高浓度的溶解性有机物、氨氮等污染物、含盐量高、可生化性差等特点,现已成为废水处理所面临的主要瓶颈和难题。本实验在电化学氧化的基础上,以Ti/RuO₂-IrO₂为阳极、Fe-FeOx/炭气凝胶（FCA）为阴极,质子交换膜为隔膜,无须外加金属催化剂,充分将阳极氧化作用和阴极还原产物的氧化作用相结合,应用阴阳极协同技术,采用新型电化学体系有效地降解反渗透浓水（ROC）中污染物。（1）炭气凝胶（CA）电极采用溶胶凝胶法制备,FCA电极采用一步合成法制得。通过物理化学测试和表征,结果显示:CA基底材料具有良好的导电性为26.67 S/cm,较低的密度0.2965 g/cm³和比较大的比表面积495.225 m²/g。扫描电镜（SEM）谱图显示:制备的CA材料,在高温炭化前后,均具有良好的三维网络结构和比较发达的空隙。加入铁源后,FCA电极导电性、机械强度和电化学性能均有所增强。SEM、透射电镜（TEM）和X射线衍射（XRD）谱图显示:FCA电极同样具有三维网络结构,纳米铁颗粒主要以铁和铁氧化物的形式,被比较均匀负载到CA基底材料上。通过电化学测试,得知制备的电极具有很好的氧还原反应性能。（2）本文考察不同因素下CA电极H₂O₂产量情况。在电流为50 mA、曝气量为0.7L/min和pH=7较优的条件下,H₂O₂的产量为648.14 mg/L。通过直接和间接的方法证明为了·OH是反应体系中主要的活性自由基。为了进一步验证FCA电极电化学氧化性能,对甲基橙的废水的脱色进行研究,在最优条件下,经过180 min,甲基橙的脱色率为100%。CA电极和FCA电极均具有良好的稳定性和使用寿命。（3）本文研究了序批式实验条件下,对阴阳极单独作用和阴阳极协同作用,考察不同因素对氨氮和化学需氧量（COD）的降解情况。实验结果表明:在最优条件下,通过阴阳极协同作用,氨氮和COD的降解效果要好于阴阳极单独作用的降解效果。阴阳极协同作用下,阳极室,经过90 min,氨氮的浓度由原来的50 mg/L降到了0 mg/L,而COD经过120 min由原来的150 mg/L降到了33.51 mg/L。相应的阴极室,氨氮的浓度由原来的50 mg/L经过210 min降解到0 mg/L,COD经过240 min由原来的150 mg/L降到了42.11 mg/L。（4）在序批式实验研究的基础上,建立了连续式实验,在最优的条件下,考察不同进水方式对模拟ROC中氨氮和COD降解效果的影响。在阴阳极同时进水和同时出水的情况下,氨氮和COD的降解效果最好。氨氮经过8 h由原来的50 mg/L降低到6.22mg/L,相应的COD经过8 h的降解由原来的150 mg/L降低到39.51 mg/L。更多还原

【Abstract】 Reverse osmosis is a membrane separation technique that uses a pressure difference as the driving force by selecting the function of the permeation membrane.Rapid development in the past 20 years,due to the simple process of reverse osmosis,low energy consumption.It is now widely used in seawater desalination,brackish water desalination,and wastewater treatment in various industries.At the same time,it is combined with ion exchange to produce high-purity water.Its application range is continuously expanding,and it is of great significance for environmental protection and sustainable development,and has huge economic benefits for water-scarce areas.However,the reverse osmosis process usually produces about one-third of concentrated water,which has now become a major bottleneck and a problem for wastewater treatment.Due to the high concentration of dissolved organics,ammonia and other pollutants,high salt content,poor biodegradability,etc.In this experiment,based on the electrochemical oxidation,using Ti/RuO₂-IrO₂ as the anode,Fe-FeOx/carbon aerogel（FCA）as the cathode,and the proton exchange membrane as the separator,no external metal catalyst is required.The oxidation of the anode is fully combined with the oxidation of the cathodic reduction product,the cathode-anode synergy technology is applied and a new electrochemical system is used to effectively degrade pollutants in reverse osmosis concentrates.（1）The carbon aerogel electrode was synthesized by the sol-gel method,and the Fe-FeOx/carbon aerogel electrode was prepared by one-step synthesis method.Through physical and chemical tests and characterization,the results show that the carbon aerogel base material has a good conductivity of 26.67 S/cm,a lower density of 0.2965 g/cm³ and a relatively large specific surface area of 495.225 m²/g.The SEM spectrum shows that the prepared carbon aerogel material has good three-dimensional network structure and well-developed voids before and after high-temperature carbonization.After adding iron source,the conductivity,mechanical strength and electrochemical performance of FCA electrode have been enhanced.SEM,TEM and XRD spectra show that the FCA electrode also has a three-dimensional network structure,and the nano-iron particles are mainly in the form of iron and iron oxides.It is relatively uniformly loaded onto the carbon aerogel base material.Through electrochemical tests,the prepared electrodes have good oxygen reduction performance.（2）The production of H₂O₂ in CA electrode under different factors was also examined.Under the optimal conditions of current with 50 m A,aeration volume of 0.7 L/min and pH=7,the yield of H₂O₂ was 648.14 mg/L.What’s more,the direct and indirect methods proved that·OH is the main active free radical in the reaction system.In order to further verify the electrochemical oxidation performance of FCA electrode,the decolorization of methyl orange wastewater was also studied.Under optimal conditions,after 180 min,the decolorization rate of methyl orange was 100%.CA electrode and FCA electrode have good stability and service life.（3）The degradation of ammonia nitrogen and COD by different factors under sequential batch condition was performed with the anode and cathode separation and synergy function.The experimental results show that under the optimal conditions,the effect of ammonia and COD degradation through anode and anode synergy is better than the effect of cathode and anode alone.Anode and anode synergy,in the anode compartment,after 90 minutes,the concentration of ammonia nitrogen decreased from 50 mg/L to 0 mg/L,while COD decreased from 150 mg/L to 33.51 mg/L after 120 minutes.In the corresponding cathode chamber,the concentration of ammonia nitrogen was degraded from 50 mg/L to 210 mg/L after 210 min,and the COD was reduced from 150 mg/L to 42.11 mg/L after 240 min.（4）Based on the sequential batch experiments,a continuous experiment was established.Under the optimal conditions,the effects of simulated ammonia-nitrogen and COD degradation in reverse osmosis contaminates were examined through different influent modes.In the case where the anode and the cathode simultaneously feed water at the same time,ammonia nitrogen and COD have the best degradation effect.With ammonia decreased from50 mg/L to 6.22 mg/L after 8 h,and the corresponding COD decreased from 150 mg/L to39.51 mg/L after 8 h.更多还原