【作者】 李爽；

【导师】 衣守志；

【作者基本信息】 天津科技大学 ， 应用化学， 2012， 硕士

【摘要】 近几十年来,随着人口的增长,经济、工业的发展,人类对淡水的需求日益增加。海水是水资源中最丰富、供应最稳定的水源,开发利用海水势在必行。目前,主要的海水淡化工艺仍是反渗透法,反渗透膜对进水水质的要求较高,海水若未经预处理直接进入反渗透装置,会造成严重的膜污染,所以在海水淡化前对海水进行预处理十分必要。由于海水中含有过量的硼,它对动植物及人体会产生较大的危害,世界卫生组织(WHO)规定灌溉水中硼含量不高于1mg/L,饮用水中硼含量不超过0.3mg/L,因此,海水脱硼研究是十分必要的。本研究采用碱化絮凝法对渤海海水进行脱硼预处理,考察了碱化剂、絮凝剂种类、pH值、温度、絮凝剂用量、慢搅时间和静沉时间对脱硼效果的影响,并分别对碱化剂、铝系和铁系絮凝剂进行正交实验设计,确定了最佳的工艺条件。结果表明,最佳的碱化剂为NaOH,脱硼率达到79.9%,进行正交实验后得到的脱硼率为81.0%,余硼含量为0.96mg/L。采用絮凝剂脱硼时,铝系絮凝剂聚硅酸氯化铝镁(PACSM)效果最佳,脱硼率为86.8%,正交实验得到的脱硼率为87.5%,余硼含量为0.63mg/L;最佳的铁系絮凝剂—聚硅酸铝铁(PAFCS)得到的脱硼率为92.7%,正交实验后的最佳脱硼率为93.6%,余硼含量达到0.32mg/L。此外,探讨了碱化絮凝过程中的中间产物Mg(OH)2对硼的吸附热力学和动力学特性。结果表明：Mg(OH)2对硼具有较强的吸附能力,吸附过程符合Langmuir等温吸附模型、Freundlich等温吸附模型以及Lagergren准二级动力学模型,此吸附过程为放热过程,低温有利于Mg(OH)2对海水中硼的吸附。更多还原

【Abstract】 In recent years, with the growth of population, the development of economic and industry, human have the demand for fresh water is increasing. Seawater is the most abundant and steady water sourse, exploiting seawater is imperative under the situation. Currently, the reverse osmosis (RO) is still the main desalination technology, the membrane needs better water quality, if seawater enter RO device directly without being pretreated, the membrane will be polluted seriously, so the pretreatment of seawater is very indispensable before desalination. Due to seawater contains excessive of boron, it have great harm to the plant, animals and human, the World Health Organization (WHO) demand the content of boron in the irrigation water is less than1mg/L, and in the drinking water does not exceed0.3mg/L, therefore, study on boron removal is very indispensable.Boron removal from Bohai seawater by alkalization-flocculation have been investigated. The influences of main single factors such as the types of alkalizer and flocculant, pH, temperature, the dosage of flocculant, slow stirring time and stirring time on the boron removal have been explored, and do the orthogonal experiment for the alkalizer, Al and Fe flocculants, the optimal process conditions have been determined. The results showed that the best alkalizer is NaOH, the rate of boron removal obtained79.9%, and81.0%was obtained in the orthogonal experiment, the remaining amount of boron was0.96mg/L. When the flocculants were applied in the boron removal, the best flocculant was polyaluminium chloride silicate magnesium (PACSM) in the A1flocculants, the rate of boron removal was86.8%, and87.5%was obtained in the orthogonal experiment, the remaining amount of boron was0.63mg/L; the best Fe flocculant was poly aluminium ferrumiron chloride silicate (PAFCS), the rate of boron removal was92.7%, and93.6%was obtained in the orthogonal experiment, the remaining amount of boron obtained0.32mg/L.In addition, adsorption thermodynamic and kinetic properties of boron adsorption by Mg(OH)2which was the intermediate of alkalization-flocculation process have been explored. The results showed:Mg(OH)2had a strong boron adsorption capacity, and the process agreed with the Langmuir adsorption isotherm model, Freundlich adsorption isotherm model and the Lagergren pseudo-second kinetic model, and the adsorption process was an exothermic process, boron of seawater was adsorbed by Mg(OH)2easily at low temperature.更多还原