【作者】 韩非；

【导师】 顾平；

【作者基本信息】 天津大学 ， 环境工程， 2012， 博士

【摘要】 日本福岛地震引发的核电站放射性物质泄漏引起了人们的广泛关注。在这些放射性物质中，铯是半衰期较长的高释热裂变产物，其存在对环境造成长期威胁。本文利用亚铁氰化铜作为吸附剂，采用微滤膜进行固液分离，开发出累积二级逆流吸附-微滤工艺去除模拟废水中的铯，获得了较高的去污因数和浓缩倍数，为应对核突发事件提供了技术支撑。试验制备出分子式为Cu₂Fe（CN）₆·7H₂O的亚铁氰化铜，其对铯的吸附过程符合Freundlich吸附等温式和拟二级吸附动力学模型，离子交换是主要的作用机理。当溶液的初始铯浓度约为100μg/L，pH值在2.6¹0.9范围内时，铯的分配系数大于2.94×10⁶mL/g。溶液中与铯共存的K⁺离子和Na⁺离子的浓度分别低于20mg/L和1000mg/L时，不影响铯的去除。亚铁氰化铜吸附铯以后在水溶液中不解吸。升高溶液温度有利于铯的去除。使用常规吸附-微滤工艺处理含铯废水，随着运行时间的增加，出水铯浓度呈下降的趋势。当亚铁氰化铜的投加量为20⁸0mg/L时，得到的平均去污因数为287¹349。由于离子交换作用，出水中铜的浓度有所升高，但是其浓度以及可能被引入的氰化物浓度均满足国家《生活饮用水卫生标准》（GB5749-2006）要求。针对亚铁氰化铜吸附水中的铯，开发出二级逆流吸附-微滤工艺，并建立了数学模型；采用该模型可较准确地预测出水中的铯浓度，并在烧杯试验以及小试试验中进行了验证。当水中初始铯浓度约为100μg/L，亚铁氰化铜的投加量为40mg/L，稀释因子分别为0.7和0.4时，烧杯试验获得的去污因数分别为615和1123，与模型计算值接近。二级逆流吸附-微滤工艺小试试验的验证结果表明，出水铯浓度随运行时间的增加基本不变，在稀释因子分别为0.7和0.4时，得到的去污因数分别为593和964。与常规吸附-微滤工艺相比，在相同的吸附剂投加量下去污因数可提高1²倍，膜分离器内悬浮固体浓度的实测值接近计算值，膜污染速率小，可获得更大的浓缩倍数。更多还原

【Abstract】 The leakage of radioactive materials from Fukushima Daiichi Nuclear PowerPlant due to the earthquake in Japan caused the people’s extensive concern. Amongthe radioactive nuclides, cesium has high heat fission and a long half-life. Theexistence of cesium becomes a long-term threat to the environment. In this paper,countercurrent two-stage adsorption-microfiltration process was developed for thecesium removal from simulated liquid waste. Copper ferrocyanide and microfiltrationmembrane were used for adsorption and solid-liquid separation, respectively. Thepurpose of this research was to acquire higher decontamination factor andconcentration factor, and to provide technical support in response to the nuclearincident.Copper ferrocyanide with the molecular formula of Cu₂Fe（CN）₆·7H₂O wasprepared in this study. The adsorption behavior of cesium on copper ferrocyanidecould be best described by the Freundlich isotherm model and a pseudo-second orderkinetic model. Ion exchange was the main mechanism during the adsorption process.The distribution coefficient was more than2.94×10⁶mL/g when the pH of solutionwas between2.6-10.9, and the initial cesium concentration was approximately100μg/L. The existence of K⁺and Na⁺with the concentration below20mg/L and1000mg/L in the solution did not affect the removal of cesium. Desorption could beignored after the adsorption of cesium on copper ferrocyanide. The highertemperature of solution could help the adsorption process.Lab-scale tests with a conventional adsorption-microfiltration process were usedfor the removal of cesium from simulated liquid waste, the concentration of cesium inthe effluent decreased gradually with the operation time, and the meandecontamination factor was between287-1349with the copper ferrocyanide dosagebetween20-80mg/L. Because the ion exchange, the concentration of copper in theeffluent was higher than that in the influent, however, both the concentration ofcopper and the cyanide, which could be introduced into the effluent, met the ChineseStandards for Drinking Water Quality （GB5749-2006）.Based on the adsorption of cesium on copper ferrocyanide, a countercurrenttwo-stage adsorption-microfiltration process was developed and the corresponding mathematical model was established. The concentration of cesium in the effluentcould be predicted more accurately by the model. A series of jar tests and lab-scaletests were achieved to verify this model. In the jar tests, the decontamination factorsobtained were615and1123when the initial cesium concentration was approximately100μg/L, the dosage of copper ferrocyanide was40mg/L, and the dilution factorswere0.7and0.4, respectively. The experimental values fitted quite well with thevalues calculated by the model.The results of lab-scale tests with the countercurrent two-stageadsorption-microfiltration process showed that the effluent cesium concentrationremained stable with operation time, and the decontamination factors obtained were593and964when the dilution factors were0.7and0.4, respectively. Compared withthe conventional adsorption-microfiltration process, the decontamination factorobtained could increase1-2times with the same dosage of adsorbent by using thecountercurrent two-stage adsorption-microfiltration process. The experimental valuesof suspended solid in the membrane separator were close to those of calculated ones.Membrane fouling rate was slower and a higher concentration factor could beacquired in the countercurrent two-stage adsorption-microfiltration process.更多还原