【作者】 谢德华；

【导师】 施周；

【作者基本信息】 湖南大学 ， 市政工程， 2012， 博士

【摘要】 论文基于Donnan渗析原理，采用均相阳离子交换膜分离去除废水中常见的Cu²⁺、Mn²⁺和Zn²⁺等重金属离子，研究了实验运行条件、重金属离子和溶液的物理化学性质对膜分离去除Cu²⁺、Mn²⁺和Zn²⁺等重金属离子效果的影响机制，膜的污染和清洗，以及膜离子交换重金属离子的动力学和热力学现象，构建了离子交换膜化学反应器并初步应用于对重金属离子分离去除实验。研究发现离子交换膜在无外加电压条件下能有效分离去除水中的Cu²⁺、Mn²⁺和Zn²⁺等重金属离子，当重金属离子浓度为0.0787mmol/L时，实验条件下，Cu²⁺、Mn²⁺和Zn²⁺的去除率可分别高达85%、79%和75%。提高下列任一影响因素数值，如水温、补偿离子浓度、水力停留时间和搅拌速度，均会增加膜对重金属离子的去除率，但增加到一定数值后再增加，对提高去除率无明显改善。重金属离子过膜迁移可分为三步：重金属离子由给体池进入膜内（第一步）、重金属离子在膜内迁移（第二步）、重金属离子由膜内进入受体池（第三步）。对膜进行预处理有助于促进第一步迁移，而增加补偿离子浓度则可同时促进第二步和第三步迁移，但对第一步迁移无明显影响。对Cu²⁺、Mn²⁺和Zn²⁺等带相同电荷重金属离子而言，在相同浓度下，其水化离子半径越小，离子迁移速度就越快，离子交换膜对其去除能力就越强；当水化离子半径相近时，阳离子交换膜对原子序数小的重金属离子的去除能力更强，故试验膜对重金属离子去除能力大小依次为Cu²⁺＞Mn²⁺＞Zn²⁺。重金属离子共存时，各离子被同步去除，但各离子之间存在竞争干扰。溶液中pH值的变化是否对膜分离去除Cu²⁺产生影响，取决于溶液中H+浓度与溶液中Cu²⁺浓度之间的相对大小。当给体液中H+浓度为Cu²⁺浓度10倍左右时，给体液中H+与受体液中的补偿离子K+的Donnan渗析推动力作用方向相反，起抵消作用，阳离子交换膜分离去除Cu²⁺的能力显著降低；当受体液中H+浓度较高时，H+与K+同时发挥Donnan渗析推动力作用，但由于膜交换速率和交换容量的限制，这一叠加效应不明显。二氧化硅、三氧化二铝、碳酸钙、腐殖酸、氨水、乙二胺四乙酸、阳离子表面活性剂、阴离子表面活性剂、三氯化铁等人为添加污染物，在长时间运行后均会不同程度地降低离子交换膜对Cu²⁺的去除效果。二氧化硅、三氧化二铝等低溶解度的无机物，以及非离子表面活性剂等不会和Cu²⁺发生物理化学反应，也不易附着于膜表面，对膜去除Cu²⁺影响较小。乙二胺四乙酸、氨水、腐殖酸和阴离子表面活性剂会与Cu²⁺形成离子半径较大的不易离子交换的络合态铜离子，碳酸钙、氨水、阴离子表面活性剂会导致溶液呈碱性使溶液中游离态Cu²⁺浓度下降，腐殖酸、碳酸钙和三氯化铁胶体会沉积在膜表面阻塞交换孔道而影响离子交换过程，以上情况均会导致Cu²⁺去除率下降。进一步研究显示受污染膜经酸碱清洗后，其离子交换性能恢复良好。研究结果表明：在温度25℃，溶液pH=6.00时，膜对Cu²⁺饱和交换容量为0.506mmol/g；对离子交换膜的动力学和热力学研究发现，膜对Cu²⁺离子交换反应符合一级反应动力学方程，该离子交换反应能自发进行，为吸热反应和熵变增加的过程。将离子交换分离装置和化学反应沉淀器结合构建成离子交换膜化学反应器并用于对Cu²⁺的处理。试验结果表明从受体池进入化学沉淀反应器的Cu²⁺能很好的沉淀下来，而去除Cu²⁺后的含高浓度补偿离子K+的溶液回流到受体池循环使用，以节约了药剂及水的成本。离子交换膜化学反应器是一种可用于水中重金属离子分离处理的有应用前景的新技术，该技术具有低能耗，操作简单，运转费用低且无二次污染等优点。更多还原

【Abstract】 Based on Donnan dialysis, the removal of heavy metal ions such as copper,manganese, and zinc has been investigated using a homogeneous cation exchangemembrane. The study includes the effects of experimental operation conditions andphysical and chemical properties of the heavy metal ions and solution on the removalof heavy metal ions, the membrane fouling and cleaning, the dynamic andthermodynamic phenomena of the membrane for the heavy metal ions exchanging. Atthe last, an ion exchange membrane reactor is constructed and tested for the heavymetal removal.It is found that the tested heavy metal ions can be removed by the ion exchangemembrane without applying external electric potential，and when the heavy metalconcentrations is0.0787mmol/L, the removal efficiency of heavy metal ions such ascopper, manganese and zinc, can be up to85%,79%and75%under the experimentalcondition. Increasing any value of the single factor such as temperature, concentrationof compensation ion, hydraulic retention time and stirring speed within a reasonablerange will result in rise of the metal ions removal efficiency.Migration of heavy metal ions through the membrane can be divided into threesteps: the metal ions entering into the membrane from the donor cell （the first step）,mobile of the metal ions in the membrane （the second step）, the metal ions enteringinto the receptor cell from the membrane （the third step）. Preconditioning membranewill improving the ion migration in the first step. Increasing concentration ofcompensation ion can promote the migration in the second and third step, but nosignificant effect on the first step of migration was observed.As for the heavy metal ions of Cu²⁺, Mn²⁺and Zn²⁺with the same charge, thesmaller the size of its hydrated ion, the faster the migration of the ions, and the higherremoval efficiency the membrane can be achieved at the same ion concentrations.When the size of hydrated heavy metal ions is approximately same, the ion with loweratomic number will pose higher removal efficiency to the membrane. Thus, theremoval capacity of membrane for the tested metal ions is ranged as Cu²⁺＞Mn²⁺＞Zn²⁺. When different heavy metal ions coexist, the ions are simultaneously removedwith less efficiency due to interference between each others.Whether pH of the influent solution imposes an effect on the removal of Cu²⁺ depends on the concentration ratio of H+and Cu²⁺. When the H+concentration is10times higher than the Cu²⁺concentration in the influent, H+imposes an opposite effectof Donnan dialysis of K+ions, resulting in and the removal of Cu²⁺decreasedsignificantly. When H+concentration in the compensation solution is high, H+and K+play the same role in of Donnan dialysis, however this additive effect is not soobvious for the film exchange rate and exchange capacity constraints.Adding of compounds such as silicon dioxide, aluminium oxide, calciumcarbonate, humic acid, ammonia, complexon II, cationic surfactant, anionicsurfactant and iron trichloride etc. as pollutants in influent, will decrease the removalof copper ion after long time operation; if there is no occurrence of physical andchemical reaction between copper ion and the adding inorganic substances, such assilica, alumina and non-ionic surfactant, the effect on the exchange membraneseparation of copper ion would be less, and if the complex compounds are formedbetween the Cu²⁺and additives such as complexon II, ammonia, humic acid andanionic surfactant, the serious effect on removal of Cu²⁺is observed; Since appearingcalcium carbonate, ammonia and anionic surfactant will lead to the solution becomingalkaline and then decreasing free Cu²⁺, and humic acid calcium carbonate andcolloidal iron hydroxide are likely attached on the membrane surface and therefore toblock the pore of the membrane, the reduction of exchange capacity of ion membraneis resulted in. Further, it is found that properties of a fouling ion exchange membranecould be well recovery when it is washed by acid and alkali solution.The exchange capacity of ion-exchange membrane for Cu²⁺is determined as0.506mmol/g under the condition of temperature25℃and pH of the solution6.00.Dynamic and thermodynamic study indicates the ion exchange reaction of Cu²⁺follows the first order kinetics, and exchange process is endothermic and entropyincreasing.An ion exchange membrane chemical reactor is constructed by combining ionexchange separation unit with chemical precipitation chamber, and is applied forcopper ion removal. The results shows that the copper ion leasing from receptor poolof the separation unit can be settled down in the chemical precipitation chambersuccessfully. The compensation potassium after copper precipitated is recycled to thereceptor pool for saving the cost of water and chemicals.Ion exchange chemical reactor which explored in the study is a promise newtreatment technology for separation of heavy metal ions in water, with advantages oflow energy consumption, easy and low cost operation, no secondary pollution.更多还原