【作者】 焦世珺；

【导师】 郑怀礼；

【作者基本信息】 重庆大学 ， 市政工程， 2010， 博士

【摘要】 混凝工艺是水处理中最重要的处理工艺之一。混凝工艺的核心技术是混凝剂的开发,混凝剂的优劣是决定混凝效果甚至整个水处理效果的关键因素之一。混凝剂可与水溶液中的溶质、胶体和悬浮物颗粒产生混状物沉淀,从而达到去除水体中各种污染物质的目的。开发新型高效优质混凝剂产品以提高水处理效果、降低成本、拓展应用领域,是水处理工作中的一项重要任务。目前,一方面是水资源的不断减少,另一方面是污水和废水的排放规模不断加大种类不断增加,水中污染物的成分日趋复杂,对环境的危害日益加重。因此,水处理的难度进一步加大,特别是传统的混凝剂已不能满足现有混凝技术的需要,新型混凝剂的研究和开发已成为当今世界各国的重要研究课题之一。聚磷硫酸铁（简称PPFS）是基于磷酸根对聚合硫酸铁（简称PFS）的强增聚作用,在PFS制备过程中引入了适量的磷酸盐,使得PPFS中产生了新一类高电荷的带磷酸根的多核中间络合物。与传统的无机混凝剂相比较,它具有絮体形成快、颗粒密度大、沉降速度快、对TP去除率高等特点,且具有安全无害、无二次污染、高效低耗、成本低廉、附加值高、对水温和pH值适应范围广等优点,可部分取代价格昂贵的有机高分子混凝剂。PPFS是目前有极好的发展和应用前景的铁系物结高分子混凝剂之一,可以用于各种工业废水、生活污水及饮用水的处理工艺中。论文的主要研究内容和结论如下:（1）PPFS制备条件的单因素分析表明,制备温度为80℃、制备时间为60min时有利于PPFS的制备,nPO₄^3-/nFe³⁺、B分别为20%时,产品稳定且混凝效果最好。在此基础上,选择了nPO₄^3-/nFe³⁺、B和制备温度进行了正交试验,结果表明在nPO₄^3-/nFe³⁺为0.3、B为30%、制备温度为80℃条件下制备的PPFS对模拟废水的去除效果最好。两次试验的B值有所不同,这表明制备因素之间有一定的交互作用。（2）考察了制备的PPFS的稳定性。与PFS相比,由于PPFS中引入了PO₄^3-,从而改变了Fe的聚合形态,并削弱了Fe的水解能力,使得PPFS更加稳定。（3）研究了PPFS水解过程中的优势形态,并考察了引入PO₄^3-后,PPFS在结构、组成成分及表面微观形貌上的变化。根据逐时络合比色法,在PPFS中铁的主要形态是Fea和Fec,Feb为前两者的过渡平衡态,且含量很少。发挥好的混凝效果主要是以高铁聚合物存在的Fec形态。通过紫外吸收光谱分析,得出聚磷硫酸铁混凝剂中铁的形态主要主要以Fe₅（OH）₉⁶⁺、Fe₅（OH）₈⁷⁺、Fe₅（OH）₇⁸⁺、Fe₆（OH）₁₂⁶⁺、Fe₇（OH）₁₂⁹⁺和Fe₇（OH）₍11_<sup>10+等形式存在。与PFS的紫外光谱吸收相比,PPFS在450nm处产生一新的吸收峰,这说明磷酸根的引入改变了PFS中铁的形态,可能生成了[Fe_x （OH）_y]₂H₂PO₄^{（6x-2y-1）+}、[Fe_x （OH）_y]₂HPO₄^{（3x-y-1）+}、[Fe_x （OH）_y]₂PO₄^{（6x-2y-3）+}等大分子络合物,其具体结构还需进一步研究。并且nPO₄^3-/nFe³⁺为0.3,B为0.2时,PPFS的高聚态浓度较大。通过红外光谱分析可知,PPFS在3400cm-1和1640cm-1处的2个特征吸收峰峰形基本相似,只是峰的面积和波数有所变化,可认为是分子中的-OH的伸缩振动和结合水分子H-O-H的弯曲振动,而在波数为900～1200cm-1峰形的变化比较明显,这些峰可能为Fe-OH-Fe或Fe-PO₄的振动,这说明聚合硫酸铁和磷酸根复合后,PFS中的水解络合铁离子与共存的磷酸根发生了反应生成Fe-PO₄聚合物。通过X-射线衍射分析可知,PPFS中主要Fe4.67（SO₄）6（OH）₂·20H₂O、FeHSO₄·4H₂O、Na₂HPO₄·2H₂O等物质存在。XRD分析表明由于PO₄^3-的加入,形成新的磷铁聚合物物相,说明PPFS是在PFS基础上制备的一种新的无机高分子复合混凝剂。SEM表征分析表明,PO₄^3-的加入使得在PFS表面形成了大量的聚合物支链,这赋予PPFS优异的架桥作用,增强了其混凝性能。（4）将PPFS实际应用至城镇生活污水的试验中,发现PPFS对SS、COD和TP,特别是TP,均有良好的去除作用。采用单因素试验方法,针对PPFS处理生活污水的主要影响因素加以分析,包括nPO₄^3-/nFe³⁺、B和投加量。以生活污水中COD、TP的去除率为考察对象,采用Box-Behnken中心组合试验和响应面分析方法对主要影响因素加以优化,得到了二次响应曲面模型以及优化的水平值。结果表明PPFS混凝去除COD的最优因素条件为:nPO₄^3-/nFe³⁺为0.28,B为18.76%,投加量为77.57 mg/L,在此条件下,COD去除率平均值为75.98%。对TP的最适因素条件为:nPO₄^3-/nFe³⁺为0.36,B为18.26%,投加量为71.37 mg/L,在此条件下,TP去除率平均值为93.64%。通过回归分析,COD和TP模型拟合性良好,但COD的相关性低于TP,这主要是由于混凝实验和COD测定,特别是低浓度的COD值测定时产生的误差所致。此外,还与PFS处理城镇生活污水相比的效果进行的对比,结果表明PPFS的除浊、COD、TP效果好于PFS,且污水处理后pH值也较稳定。PPFS的用于生活污水处理时,存在电中和、吸附架桥、网捕等多种的作用,但絮凝效果最好时以吸附架桥作用为主。（5）选用TOC的去除率和在紫外波长为254nm处的吸光度作为有机物去除的总体指标,选用6种邻苯二甲酸酯类化合物以及15种多环芳烃类化合物为细化指标,考察了PPFS对嘉陵江水的实际去除效果。从TOC和UV254的测定结果看,PPFS对嘉陵江水中的有机物有一定的去除作用。通过对PAEs和PAHs类物质的检测结果来看,PPFS对这两类有机物的去除效果较为显著。通过响应面法对影响混凝效果的因素进行优化,得到了二次响应曲面模型以及优化的水平值。得到的TOC二次响应曲面模型拟合性好, PPFS混凝去除TOC的优化因素条件为: nPO₄^3-/nFe³⁺为0.30,B为28.54%,投加量为16.35mg/L,得到TOC的去除率平均值为21.71%。。PPFS的用于嘉陵江水的处理时,絮凝效果最好时以吸附架桥作用为主。更多还原

【Abstract】 Currently, flocculation has already become an inportent part of water treatment process. The core technology of flocculation process was the development of flocculants. It was the characteristics of flocculant which determined not only the flocculation effect but also the overall water treatment effect. The floc and precipitation produced by interaction between flocculant and colloidal particles and suspended matter contained in aqueous solutes were the key to remove various contaminants in water through flocculation. Development of new high quality flocculant was an important task of water treatment to improve the coagulant effect in water treatment, to reduce costs and to explore new application area. At present, one of water environment status was the continuous decrease of water resources, two issues were significant in water science, one of which was the limited water supply, and the other of which was the problem of wastewater. To be specific, the volume of wastewater was increasing dramatically with more and more kinds of pollutants and increasing complexity of the composition. Therefore, the difficulty of further treatment was increasing. Because the traditional flocculant could not meet the requirements of flocculation technology any longer, new research and development of flocculants has already been one of the important research topics.Because PO₄^3- played an important role to increased accumulation of Polymeric Ferric Sulfate （referred to as PFS）, a certain quantity of PO₄^3- was introduced into the preparation of PFS and the Polymeric Phosphate Ferric Sulfate （referred to PPFS） and a new type of multi-core highly charged intermediate complex was produced. Compared to traditional inorganic flocculants, it possessed such characteristics as faster floc formation, higher particle density, higher settlement rate and higher removal rate of TP. In addition, it had numerous advantages such as safety, no secondary pollution, high efficiency, low consumption, low cost, high added value, adaptation to a wide range temperature and pH value. It could be used to replace expensive organic polymer flocculant partially. Nowadays, PPFS is a kind of inorganic polymer iron flocculants which has excellent prospects for development and application, which could be used in the treatment of a variety of industrial wastewater, sewage and drinking water.The main contents and conclusions in this study were as following:（1） By one factor analysis of PPFS preparation conditions, it was indicated that the product was most stable and the effect of flocculation was the best when the preparation temperature was 80℃, preparation time was 60min and the molar ratio nPO₄^3-/nFe³⁺ was 0.3 and B was 20%. On this basis mentioned above, the orthogonal was carried out with nPO₄^3-/nFe³⁺, B and preparation temperature as the three factors. The results showed that the treatment effect was the best when nPO₄^3-/nFe³⁺ was 0.3, B was 30% and the preparation temperature was 80℃.The B value obtained from the two experiments were different, indicating that there were certain interactions between preparation factors.（2） Stability of the PPFS was studied. Compared with the PFS, due to the introduction of PO₄^3-, the form of Fe in the aggregate was changed and the hydrolysis ability of Fe was weakened, which made PPFS more stable.（3） Advantagous form of the hydrolysis process of PPFS was studied, and the changes in the structure, composition and surface topography of PPFS after the introduction of PO₄^3- was investigated. Through timed spectrophotometry of Fe-ferron complexation, it was showed that the amount of Fea and Fec in Polymeric Phosphate Ferric Sulfate （PPFS） flocculants were the important factors in the three, while Feb was the transition states and the amount of Feb was small which had no significant effect. Play good flocculation mainly high polymer which exists with the forms of Fec. The Ultraviolet-visible spectrum showed that main forms of iron were Fe5（OH）96+、Fe5（OH）87+、Fe5（OH）78+、Fe6（OH）126+、Fe7（OH）129+和Fe7（OH）1110+ in PPFS. Compared with the UV absorption spectra of PFS, a new absorption peak of PPFS generated at the 450nm, indicating that the introduction of phosphate changed the form of iron in PFS, [Fex （OH）y]2H2PO₄（6x-2y-1）+、[Fex （OH）y]2HPO₄（3x-y-1）+、[Fe_x （OH）_y]₂PO₄^{（6x-2y-3）+} and other macromolecular complexes might be generated, the specific structure of which should be studied furtherly. The high-polymeric of PPFS was more when nPO₄^3-/nFe³⁺ was 0.3 and B * was 0.2. Infrared spectra showed that PPFS had similar characteristic absorption peak at 3400cm-1 and 1640cm-1, but peak area and the wave number were changed, which could be considered as elements of the-OH stretching vibration and the combination of H-OH bending vibration of water molecules. The peak shape changed more obviously in the wave number of 900 1200cm-1 and these peaks might be Fe-OH-Fe or Fe-PO₄ vibration, indicating that the polymer reaction occurred between the coexistence of iron ions in PFS and PO₄^3-, and Fe-PO₄ was formed after PFS being combined with PO₄^3- . X-ray diffraction analysis showed that the forms of iron in PPFS were mainly Fe4.67（SO₄）6（OH）2·20H₂O, FeHSO₄·4H₂O, Na₂HPO₄·2H₂O and so on. XRD analysis showed that a new phase of phosphate iron polymer was formed after the introduction of PO₄^3-. It was also indicated that PPFS was a new inorganic polymer composite flocculant based on the synthesis of PFS. SEM characterization showed that a large number of side chains on the surface of PFS polymer were formed because of the introduction of PO₄^3-, which gave excellent role of bridging to PPFS and enhanced flocculation performance dramatically.（4） Using PPFS in the treatment of urban domestic wastewater and it was found that it showed good removal effect for SS, COD and TP, among which, removal of TP was the most significant. The main influence factors for treatment of urban sewage by PPFS based on one-factor experiments with removal rate of COD and TP in sewage as the measurable indicators, were nPO₄^3-/nFe³⁺、Band dosage. Through Box-Behnken experiment design and Response Surface Analysis （RSA）, optimization grouping of these 3 main influence factors was realized; a quadratic response surface model and optimum level values were obtained. It was found that the optimization grouping of the main influence factors for the removal of COD were as following: nPO₄^3-/nFe³⁺ being 0.28,B being 18.76% and dosage being 77.57mg/L, and under the optimum conditions, the removal rate of COD was 75.98%. The optimization grouping of the main influence factors for the removal of TP were as following: nPO₄^3-/nFe³⁺ being 0.36,B being 18.26% and dosage being 7.37mg/L, and under the optimum conditions, the removal rate of TP was 93.64%.A regression analysis was utilized to evaluate the fitness of the model. However, the relevance of COD was lower than that of TP, which was mainly due to the error of flocculation experiments and COD determination, especially in low concentrations of COD. In addition, comparing the effects of urban sewage treatment by PFS and PPFS, the results showed that the removal effects of turbidity, COD and TP by PPFS were better than that by PFS, and the pH value of the former was also more stable. Flocculation was realized by the effects of adsorption and bridging comprehensive role when treating sewage by PPFS.（5） Through experiments of treating micro-polluted water by PPFS, taking TOC removal and UV absorbance at a wavelength of 254nm as general indicators of organic matter removal, and six kinds of PAEs and 15 kinds of PAHs compounds as refinement indicators, application of PPFS was studied thoroughly.. The results of TOC removal and UV254 showed it had a certain remove effect in organic compounds of micro-polluted water by PPFS. The results of PAEs and PAHs showed that there was a more significant removal effect of these two types of organics by PPFS. The main influence factors for the treatment of micro-polluted water by PPFS based on one-factor experiments with removal rate of TOC in water as the measurable indicator were nPO₄^3-/nFe³⁺、Band dosage. Through Box-Behnken experiment design and Response Surface Analysis （RSA）, optimization grouping of these 3 main influence factors was realized; a quadratic response surface model and optimum level values were obtained. It was found that the optimization grouping of the main influence factors to TOC were as following: nPO₄^3-/nFe³⁺ being 0.30,B being 28.54% and dosage being 16.35mg/L, and under the optimum conditions, the removal rate of TOC was 21.71%.A regression analysis was utilized to evaluate the fitness of the model. Flocculation was realized by the effects of adsorption and bridging comprehensive role when treating sewage by PPFS.更多还原