高浓度聚合氯化铁絮凝剂的应用基础研究
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摘要
铝盐和铁盐在水处理中用做混凝剂已广泛使用，近年来，铝盐由于残余铝的存在引发的健康问题得到了广泛关注。由此铁盐混凝剂因其高电荷、易于控制等优点得到了进一步的发展和应用。本论文主要研究高浓度聚合氯化铁(PFC)的制备和表征，以及在不同水质条件下的絮凝行为。
通过制备聚合氯化铁的条件优化和絮凝实验表明，在确定合适的稳定剂条件下，采用氧化法制备聚合氯化铁(OPFC)不仅可以获得稳定的产品品质和良好的实用效果，而且生产成本低廉，适于实际生产过程，并已成功实施，取得了较好的经济和社会效益。
为制备和表征不同的聚铁溶液，FeCl_3溶液加碱(NaHCO_3或NaOH)部分中和在选择不同的加碱速度、铁浓度和温度条件下制备不同碱化度PFC。采用逐时络合比色法对不同碱化度PFC进行形态分析。在商品浓度(＞1mol／L)的条件下，这种方法所得到的产品短时间内(＜10hr)即发生浑浊沉淀，因而降低了混凝效能。在近十年研究的基础上，本论文探讨了不同的磷酸盐作为稳定剂在BPFC溶液中的稳定效果及对铁盐溶液形态分布和混凝、沉淀过程的影响。结果表明：磷酸盐(AP)和磷酸二氢盐(AH_2P)为可实际应用的稳定剂；流动电流研究表明在P／Fe比为0.07附近对混凝较为有利；形态分析及混凝和沉淀实验证实了稳定剂的加入改变了铁溶液的水解转化途径，磷酸根参与了混凝中的水解成核过程，对沉淀形态会有影响。
通过对碱化法制备高浓度聚合氯化铁的工艺研究(BPFC)，探讨了碱的种类和稳定剂的不同加入时机对形态分布的影响，碱化剂加入速度及碱化度对稳定性的影响。研究结果表明：作为碱化剂NaHCO_3略优于NaOH；先加入稳定剂的制备方法对PFC的稳定及混凝特性有利；合适的碱加入速度对PFC的稳定比较有利；在B=0.4的区域内PFC的稳定性最差，在制备过程中应尽量避开这一区域。红外光潜分析进一步证实稳定剂的不同加入时机影响其发挥稳定作用。
针对碱化法制备PFC稳定性还有待提高，产品的成本较高等问题，结合上述对稳定剂的研究结果，实验研究了酸洗废液氧化法制备聚合氯化铁的工艺过程(OPFC)。由于在酸性条件下氯化亚铁的氧化水解过程未见研究报道，论文首先研究了二价铁离子的氧化反应过程，确定了影响氧化水解过程的主要因素。在此基础上，研究了初始酸含量，氧化剂加入方式及速度和调节碱化度所用酸的加入时机分别对聚合氯化铁形态分布，稳定性及混凝特性的影响。结果表明：初始酸含量过高
高浓度聚合氮化铁絮凝剂的应用基石出不开究
(>o.6mol/L)不利于稳定剂发挥稳定作用，氧化剂选用溶液形式投加，每looml溶
液，投加速度为1一6.smmol/min;用于调整碱化度的酸在氧化剂之后加入，对高浓度
聚合氯化铁的混凝效果和稳定性的提高有较好的影响。红外光谱分析证实不同工艺
制备过程对稳定络合作用有很大影响。
采用聚合氯化铁(P FC)絮凝剂在不同pH条件下处理高岭土悬浮液和腐殖酸溶液，
测试了絮凝过程中的zeta电位、浊度和腐殖酸的去除率变化。结果表明:pH二4时，
PFC投加量最小，剩余浊度最大，投加范围最窄;pH=7时次之;pH=10时时由于Fe(11I)
离子的正电荷减弱，电中和能力不强，而且同时产生Fe(oH)3(s)的吸附作用使得剩余
浊度最低，投加范围最宽，但投加量很大;在酸性条件下腐殖酸与Fe(III)离子最容易
发生络合反应;腐殖酸的存在并没有影响PFC的絮凝效果。
通过聚合氯化铁(PFc)对高岭土悬浮颗粒的絮凝试验中浊度和zeta电位的测试，
发现低温时在相同的PFC投药量下随着碱化度(B)的增大Zeta电位减小;在达到相
同的浊度去除，低温时PFC的投加量要小于常温时，在相同的药剂投加量低温时
Zeta电位要高于常温时;温度的降低PFC水解和沉淀速度减小，使得PFC水解中间
体更易与污染物反应，同时增强了电中和能力，减少了PFC的用量;温度的降低使
得PFC的多核经基络合物中间体水解程度减小而保持形态的时间延长，所以PFC比
传统混凝剂FeCI:处理低温低浊水更有效.
Aluminum and iron salts are commonly used as coagulants in the treatment of water for public supply. In recent years, public concerns about the potential connection between the residual aluminum in drinking water and the suspected adverse health effects, e.g., Alzheimer's disease, have been brought to intense discussion. As a result, the use of iron-based coagulants has gradually gained in popularity. It is believed that better control of the chemistry of metal salts, the desirable highly charged cationic coagulant species can be obtained prior to their application. The objectives of this research are thus to prepare and characterize polyferric chloride (PFC) and to investigate the performance of PFCs in flocculation under varying conditions.
By a series of experiments on raw material selection, preparation condition optimization and efficiency examination, it was found that oxidation method was favorable to prepare high quality and stable PFC when stabilizer existed. Moreover, this technique has been put into plant scale production with high economic and social profit.
To prepare various polyferric solutions for characterization, ferric chloride solutions have been partially neutralized by adding NaHCO3 or NaOH solution at a range of hydrolysis ratio (0lmol/L) prepared by partially neutralization was prone to precipitate in short time, then deteriorated its coagulation behavior. Based on the researches of the past ten years, different phosphates were used to stabilize the PFC solution in this paper, which mainly focused on the stabilizer effect on the precipitation time, coagulation process and species distribution of Fe(III) hydrolysis. The results suggested that phosphate (AP) and (AH2P) could influence the Fe(III) hydrolysis way and were suitable as stabilizer. The experiments of streaming current indicated that the stabilizer,could benefit the co
agulation process when the molar ratio of P to Fe is 0.07.
On the condition of concentrated solution (>lmol) and stabilizer existence, the preparing technology of BPFC had been studied by species determination and jar test. The results showed that NaHCO3 was a little better than NaOH as the injection base, the appropriate speed of base injection could improve the stability of PFC, and the pre-addition of stabilizer was the best choice in BPFC preparation. Because BPFC solution had the min-precipitation time at the basicity of 0.4, this basicity should be avoided in preparation. It can be seen from FTIR (Fourier Transformation Infra-red) spectra that the stable action of PO43" is influenced by time point of stabilizer addition.
To improve the relatively low stabilization and high cost of BPFC prepared by
basification, the pickle oxidation preparation method (OPFC) was put forward. Because few studies had addressed on the ferrous oxidation and hydrolysis in acid medium, ferrous oxidation was further investigated in this paper. The initial acid concentration, the oxidant adding way and the injection time of acid (aimed to adjust the basicity B) were all important factors, which affect the species distribution, stability and coagulation behavior of PFC. At last, the optimum oxidation conditions were obtained: (I) the initial acid concentration should be lower than 0.6mol/L; (2) the oxidant solution addition speed should be in the range of l-6.5mmol/min to 100ml Fe(II) solution; and (3) the acid injection to adjust the basicity B should be after the oxidant addition. The analysis of FTIR spectra indicated that complex forms of PO43" and Fe(III) species, which affected the stable action of PO43", were different under various preparation conditions.
The PFCs efficiency prepared by both methods has been assessed by comparing them with conventional FeCl3 salts and polyferric sulfate in coagulation experiments. The results revealed tha
通过制备聚合氯化铁的条件优化和絮凝实验表明，在确定合适的稳定剂条件下，采用氧化法制备聚合氯化铁(OPFC)不仅可以获得稳定的产品品质和良好的实用效果，而且生产成本低廉，适于实际生产过程，并已成功实施，取得了较好的经济和社会效益。
为制备和表征不同的聚铁溶液，FeCl_3溶液加碱(NaHCO_3或NaOH)部分中和在选择不同的加碱速度、铁浓度和温度条件下制备不同碱化度PFC。采用逐时络合比色法对不同碱化度PFC进行形态分析。在商品浓度(＞1mol／L)的条件下，这种方法所得到的产品短时间内(＜10hr)即发生浑浊沉淀，因而降低了混凝效能。在近十年研究的基础上，本论文探讨了不同的磷酸盐作为稳定剂在BPFC溶液中的稳定效果及对铁盐溶液形态分布和混凝、沉淀过程的影响。结果表明：磷酸盐(AP)和磷酸二氢盐(AH_2P)为可实际应用的稳定剂；流动电流研究表明在P／Fe比为0.07附近对混凝较为有利；形态分析及混凝和沉淀实验证实了稳定剂的加入改变了铁溶液的水解转化途径，磷酸根参与了混凝中的水解成核过程，对沉淀形态会有影响。
通过对碱化法制备高浓度聚合氯化铁的工艺研究(BPFC)，探讨了碱的种类和稳定剂的不同加入时机对形态分布的影响，碱化剂加入速度及碱化度对稳定性的影响。研究结果表明：作为碱化剂NaHCO_3略优于NaOH；先加入稳定剂的制备方法对PFC的稳定及混凝特性有利；合适的碱加入速度对PFC的稳定比较有利；在B=0.4的区域内PFC的稳定性最差，在制备过程中应尽量避开这一区域。红外光潜分析进一步证实稳定剂的不同加入时机影响其发挥稳定作用。
针对碱化法制备PFC稳定性还有待提高，产品的成本较高等问题，结合上述对稳定剂的研究结果，实验研究了酸洗废液氧化法制备聚合氯化铁的工艺过程(OPFC)。由于在酸性条件下氯化亚铁的氧化水解过程未见研究报道，论文首先研究了二价铁离子的氧化反应过程，确定了影响氧化水解过程的主要因素。在此基础上，研究了初始酸含量，氧化剂加入方式及速度和调节碱化度所用酸的加入时机分别对聚合氯化铁形态分布，稳定性及混凝特性的影响。结果表明：初始酸含量过高
高浓度聚合氮化铁絮凝剂的应用基石出不开究
(>o.6mol/L)不利于稳定剂发挥稳定作用，氧化剂选用溶液形式投加，每looml溶
液，投加速度为1一6.smmol/min;用于调整碱化度的酸在氧化剂之后加入，对高浓度
聚合氯化铁的混凝效果和稳定性的提高有较好的影响。红外光谱分析证实不同工艺
制备过程对稳定络合作用有很大影响。
采用聚合氯化铁(P FC)絮凝剂在不同pH条件下处理高岭土悬浮液和腐殖酸溶液，
测试了絮凝过程中的zeta电位、浊度和腐殖酸的去除率变化。结果表明:pH二4时，
PFC投加量最小，剩余浊度最大，投加范围最窄;pH=7时次之;pH=10时时由于Fe(11I)
离子的正电荷减弱，电中和能力不强，而且同时产生Fe(oH)3(s)的吸附作用使得剩余
浊度最低，投加范围最宽，但投加量很大;在酸性条件下腐殖酸与Fe(III)离子最容易
发生络合反应;腐殖酸的存在并没有影响PFC的絮凝效果。
通过聚合氯化铁(PFc)对高岭土悬浮颗粒的絮凝试验中浊度和zeta电位的测试，
发现低温时在相同的PFC投药量下随着碱化度(B)的增大Zeta电位减小;在达到相
同的浊度去除，低温时PFC的投加量要小于常温时，在相同的药剂投加量低温时
Zeta电位要高于常温时;温度的降低PFC水解和沉淀速度减小，使得PFC水解中间
体更易与污染物反应，同时增强了电中和能力，减少了PFC的用量;温度的降低使
得PFC的多核经基络合物中间体水解程度减小而保持形态的时间延长，所以PFC比
传统混凝剂FeCI:处理低温低浊水更有效.
Aluminum and iron salts are commonly used as coagulants in the treatment of water for public supply. In recent years, public concerns about the potential connection between the residual aluminum in drinking water and the suspected adverse health effects, e.g., Alzheimer's disease, have been brought to intense discussion. As a result, the use of iron-based coagulants has gradually gained in popularity. It is believed that better control of the chemistry of metal salts, the desirable highly charged cationic coagulant species can be obtained prior to their application. The objectives of this research are thus to prepare and characterize polyferric chloride (PFC) and to investigate the performance of PFCs in flocculation under varying conditions.
By a series of experiments on raw material selection, preparation condition optimization and efficiency examination, it was found that oxidation method was favorable to prepare high quality and stable PFC when stabilizer existed. Moreover, this technique has been put into plant scale production with high economic and social profit.
To prepare various polyferric solutions for characterization, ferric chloride solutions have been partially neutralized by adding NaHCO3 or NaOH solution at a range of hydrolysis ratio (0
agulation process when the molar ratio of P to Fe is 0.07.
On the condition of concentrated solution (>lmol) and stabilizer existence, the preparing technology of BPFC had been studied by species determination and jar test. The results showed that NaHCO3 was a little better than NaOH as the injection base, the appropriate speed of base injection could improve the stability of PFC, and the pre-addition of stabilizer was the best choice in BPFC preparation. Because BPFC solution had the min-precipitation time at the basicity of 0.4, this basicity should be avoided in preparation. It can be seen from FTIR (Fourier Transformation Infra-red) spectra that the stable action of PO43" is influenced by time point of stabilizer addition.
To improve the relatively low stabilization and high cost of BPFC prepared by
basification, the pickle oxidation preparation method (OPFC) was put forward. Because few studies had addressed on the ferrous oxidation and hydrolysis in acid medium, ferrous oxidation was further investigated in this paper. The initial acid concentration, the oxidant adding way and the injection time of acid (aimed to adjust the basicity B) were all important factors, which affect the species distribution, stability and coagulation behavior of PFC. At last, the optimum oxidation conditions were obtained: (I) the initial acid concentration should be lower than 0.6mol/L; (2) the oxidant solution addition speed should be in the range of l-6.5mmol/min to 100ml Fe(II) solution; and (3) the acid injection to adjust the basicity B should be after the oxidant addition. The analysis of FTIR spectra indicated that complex forms of PO43" and Fe(III) species, which affected the stable action of PO43", were different under various preparation conditions.
The PFCs efficiency prepared by both methods has been assessed by comparing them with conventional FeCl3 salts and polyferric sulfate in coagulation experiments. The results revealed tha
引文
[1] 汤鸿霄．无机高分子絮凝剂的几点新认识，工业水处理，1997,17(4)：1-5
[2] 栾兆坤．稳定性聚合氯化铁生产工艺与应用的研究，混凝技术，1999,8(3)：2-6
[3] 汤鸿霄．无机高分子复合絮凝剂的研制趋想，中国给水排水，1999,15(2)：1-4
[4] 汤鸿霄．天然水体中的环境胶体水化学，环境化学专题报告文集，1984：16
[5] 崔蕴霞等．铝盐絮凝剂及其环境效应，工业水处理，1998，18(3)：6-9
[6] 樊冠球．自来水厂用混凝剂存在的问题和解决途径，中国给水排水，1998，14(3)：42-43
[7] 郑怀礼，龙腾锐，舒型武．聚合铁类絮凝剂作用机理分析，重庆环境科学，2000,22(3)：51-53
[8] 汤鸿霄．无机高分子絮凝剂的基础研究，环境化学，1990，9(3)：1-12
[2] 栾兆坤．稳定性聚合氯化铁生产工艺与应用的研究，混凝技术，1999,8(3)：2-6
[3] 汤鸿霄．无机高分子复合絮凝剂的研制趋想，中国给水排水，1999,15(2)：1-4
[4] 汤鸿霄．天然水体中的环境胶体水化学，环境化学专题报告文集，1984：16
[5] 崔蕴霞等．铝盐絮凝剂及其环境效应，工业水处理，1998，18(3)：6-9
[6] 樊冠球．自来水厂用混凝剂存在的问题和解决途径，中国给水排水，1998，14(3)：42-43
[7] 郑怀礼，龙腾锐，舒型武．聚合铁类絮凝剂作用机理分析，重庆环境科学，2000,22(3)：51-53
[8] 汤鸿霄．无机高分子絮凝剂的基础研究，环境化学，1990，9(3)：1-12
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