羟基聚合氯化铝铁溶液的形态转化规律

采用改进的 Al-Fe-Ferron逐时络合比色法和酸滴定实验研究了典型羟基聚合铝铁(n_Al/n_Fe=9∶1,5∶5)溶液的形态转化 .结果表明 ,羟基聚合铝铁的形态转化主要由 n_Al/n_Fe值、碱化度和熟化等因素决定 ;羟基聚合铝铁的形态转化特征是优势形态之间的转变 ;当n_Al/n_Fe>5∶5,随碱化度的升高 ,[Al+Fe]_a和 [Al+Fe]_b 2类形态逐渐占优势 ;随n_Al/n_Fe值的减小 ,[Al+Fe]_a和 [Al+Fe]_c增加 ,而 [Al+Fe]_b 减少 .讨论了羟基聚合铝铁的形态转化规律 .     

聚铁硅型复合无机高分子絮凝剂的混凝性能

采用常规烧杯搅拌试验方法对聚铁硅型复合混凝剂的混凝性能进行了系统的研究 .结果表明 ,所研究聚合铁硅型复合混凝剂的混凝性能随氧化硅的种类与Si/Fe比的不同而有显明的差异 ,而碱化度的影响较为有限 .三类氧化硅中Silica(A)与Silica(B)的特性比较类似 ,显著地降低了混凝剂的电中和能力 ,仅仅在较高投药量时带来混凝效果一定的改善 .Silica(C)的引入对电中和能力的影响不大 ,但显著地提高了混凝效能 ,归因于其高效的架桥作用     

高浓度聚合氯化铝的合成及其形态分布与转化规律

以CaO为碱化剂采用一次加碱法合成了高浓度聚合氯化铝(PAC),研究了其反应特性及产品的铝形态分布与转化规律.结果表明,CaO特殊的水化反应可使PAC达到较高浓度和较高B值,PAC最高浓度可达2.1mol/L,B值为2.1.合成过程中无论高铝浓度体系还是低铝浓度体系,均存在一最佳B值,此B值下产品的Al_b含量最高.最佳B值和最高Al_b含量均随总铝浓度的升高而降低.B值小于最佳B值时,总反应主要表现为生成Al_b;B值大于最佳B值时,总反应表现为生成Al_c.     

高浓度聚合氯化铁(PFC)中铁的形态分布与转化研究

以氯化铁和无水碳酸钠为原料,加入稳定剂W,采用共聚工艺,制备了稳定高浓度的聚合氯化铁(PFC)混凝剂.采用Fe-Ferron逐时络合比色法研究了PFC中铁的形态分布情况,考察了熟化时间、碱化度(B)及n(W)/n(Fe)(W/Fe摩尔比)对PFC中铁的形态分布的影响.研究结果表明,在PFC中,由于稳定剂W与铁的水解产物间的相互作用,使得铁的水解聚合形态分布及转化情况发生了变化.碱化度(B)、n(W)/n(Fe)和熟化时间均对铁的形态分布有重要的影响.      

水分管理对稻田土壤铁氧化物形态转化的影响及其与镉活性变化的耦合关系

稻田土壤水分管理过程中铁氧化物的形态转化对土壤镉（Cd）活性和水稻Cd累积具有重要影响.以西南地区紫色水稻土为研究对象,通过室内培养试验,探讨了淹水管理方式（持续淹水,CW;干湿交替,DW）联合铁氧化物（针铁矿,G-Fe;铁粉,Fe）施用对Cd污染土壤的pH、氧化还原性质（Eh、pe+pH）、铁氧化物形态转化和Cd有效性变化的影响,分析了水分管理驱动下铁氧化物形态转化与土壤Cd活性演变的耦合关系.结果表明CW管理可显著降低土壤Cd有效性,淹水93 d后DTPA-Cd降低了17.7%~39.2%,CW联合Fe或G-Fe施用显著提升了对土壤Cd的钝化效果,其中G-Fe短期钝化效果好,淹水14 d后DTPA-Cd的含量较对照降低24.3%,而Fe则可持续钝化土壤Cd,淹水93 d后DTPA-Cd的降幅为39.2%,干湿交替下施用铁氧化物则对土壤Cd无钝化效应.相关性分析表明,无定形铁（Fe_o）的形成（P<0.01）是驱动土壤Cd有效性变化的主要原因：CW使土壤pH逐渐降低并稳定在7.4左右,且土壤保持还原状态,促进了土壤铁氧化物由结晶态（Fe_c）向Fe_o转化,进而促使Cd由可交换态向铁锰结合态转化,并最终导致Cd有效性降低;CW联合Fe、G-Fe施用显著提升了Fe_o的含量和比例,从而强化了对土壤Cd的钝化效果.研究结果揭示了水分管理联合铁氧化物施用对稻田土壤Cd活性的调控效应和机制,为Cd污染稻田土壤安全利用中水分优化管理和含铁钝化剂施用提供了科学依据.     

聚合铝的水解形态对混凝过程中磷分布转化的影响

用碱化度不同的混凝剂对水体进行混凝处理,对混凝前后水体中磷的含量、形态分布以及藻类可利用性等进行了研究.结果表明,不同碱化度的混凝剂除磷效果不同,对水体中磷形态分布的影响差别显著;Ala在混凝剂去除磷实验过程中起重要作用,碱化度越低的混凝剂除磷率越高,PACl0除磷效果最好.随着混凝剂(PACl0)投量的增加,水体中溶...     

硫酸根离子与聚合铝的反应过程及其产物形态

对不同Al/SO2-4比及碱化度条件下PACl与SO₄^2-的反应过程进行研究,分析了体系中总铝浓度及形态分布变化规律,测定了各沉淀/结晶产物的组成,并对其形貌进行了扫描电镜观察.实验结果表明:碱化度对PACl/SO₄^2-反应体系有较大影响,随着碱化度(B值)的增加,沉淀/结晶的析出速率加快,结果析出物中OH含量逐渐增加,而SO₄^2-/Al比率从0.45～0.30逐渐降低.各聚合铝水解形态与SO₄^2-反应速率上存在明显差异,从而为其混凝优势形态的分离纯化创造了条件.     

新型混凝剂处理印染废水的实验研究

采用自行制备的具有不同SiO2 :Al:Fe(摩尔比值 )和碱化度的两类新型无机高分子混凝剂聚硅酸氯化铝铁 (PSAFC)和聚硅酸硫酸铝铁 (PSAFS)各 7种 ,直接对印染废水进行处理。从中选出 2种混凝剂 ,考察了pH值、混凝剂投量等对混凝效果的影响 ,并对混凝处理后 ,印染废水出水中残留混凝剂主要成分Al、Fe、SiO2 的含量进行分析。实验结果表明 ,氯化物型 (PSAFC)和硫酸盐型 (PSAFS)混凝剂对印染废水的色度、浊度、CODCr均有良好的去除效果 ;总体而言 ,PSAFS的混凝效果略优于PSAFC ;混凝处理后印染废水出水中残留铝、铁、硅的含量均比较低 ;pH值和碱化度对混凝剂在水体中残留铝含量有影响     

Preparation of high concentration polyaluminum chloride by chemical synthesis-membrane distillation method with self-made hollow fiber membrane

A method of direct contact membrane distillation (DCMD) with a self-made hollow polyvinylidene fluoride membrane was applied to prepare high concentration polyaluminum chloride (PACl) with high Al_b content based on chemical synthesis. The permeate flux and Al species distribution were investigated. The experimental results showed that the permeate flux decreased from 14 to 6 kg/(m²·hr) at the end of the DCMD process, which can be mainly attributed to the formation of NaCl deposits on the membrane surface. The Al_b content decreased slightly, only from 86.3% to 84.4%, when the DCMD experiment finished, correspondingly the Al_c content increased slightly from 7.2% to 8.5%, and the Al_a content remained at 7% during the whole DCMD process. A PACl with Al_b content of 84% at total aluminum concentration 2.2 mol/L was successfully prepared by the chemical synthesis-DCMD method.     

Effect of in-situ formed Al hydrates through long-term aging on enhanced particle destabilization by PACl coagulation

Aging of polyaluminum chloride (PACl) coagulants could significantly influence hydrolyzed Al speciation ruling coagulation performance. The goal of this study was to investigate Al species transformation through long-term aging and its impact on coagulation performance. Two kinds of commercial coagulants (PACl-1 and PACl-2) were stored for in-situ aging tests in six months to evaluate Al species variation with time and the performance of coagulation with natural turbid waters. The results showed that CaSO₄ precipitation easily occur in a commercial PACl coagulant with time as it contains SO₄^2? and Ca²⁺. It also activates the precipitation of gibbsite Al(OH)₃ in PACl with aging. Through 180 days aging, both monomeric Al (Al_a) and polymeric Al (Al_b) substantially transform into colloidal Al (Al_c) and precipitated for both PACl coagulants. At low turbidity (10 NTU), PACl-1 has a superior turbidity reduction rate than PACl-2, while PACl-2 performs a little better turbidity reduction at high turbidity (1000 NTU) regardless of aging time. With aging time, an obvious decrease in turbidity reduction for PACl-1 coagulation is observed at low turbidity of 10 NTU, while the improvement in turbidity reduction for PACl-2 coagulation by enhanced sweep flocculation can be achieved as Al_b mostly transform into Al_c after 150 days aging. It is concluded that dominant in-situ formed Al_c after a long time hydrolysis can improve PACl coagulation efficiency in turbidity reduction by enhanced sweep flocculation, especially for low turbidity water, but the increase in preformed Al_c in PACl would worsen particle destabilization after aging.     

聚合铝混凝过程研究:不同形态硅酸的影响作用

研究了不同形态硅酸对聚合铝混凝过程的影响作用 .实验结果表明经预制形成的具有不同形态分布组成的硅酸与聚合铝 ,在投加后相互间发生了十分复杂的物理化学作用 ,并受溶液pH值的影响 ,从而最终决定了混凝效果 .反应过程中所生成的形态产物及其物化特征 ,很大程度上取决于聚合铝碱化度以及所投加的Si Al比 .其中碱化度越高 ,最终产物所带电荷越高 .而不同硅酸所起影响作用分别取决于聚合程度 ,在与聚合铝反应过程中表现出一定的规律性 .单体硅酸与单体铝迅速发生较强的络合作用 ,抑制了多聚水解铝阳离子的形成 .聚合硅酸则倾向于与聚合铝形态相互作用形成一定的胶状化合物 ,从而在溶液中稳定存在 .对于胶体硅酸 ,在聚合铝作用下迅速凝聚形成更大的聚集体 ,在颗粒物间架桥形成粗大的絮体 .所得结果对混凝机理的解释与复合混凝剂的发展提供了一定的参考作用     

电化学合成的聚合氯化铝的形态特征

采用电解法合成了聚合氯化铝溶液 ,并采用2 7AlNMR法、透射电镜等方法对其形态特征进行了研究 .2 7AlNMR法表明在电化学制备PAC中主要含有铝单体 ,铝的二聚体及Al13形态 .Al13含量与其溶液的碱化度 (B)有关 .在总铝浓度 (AlT)为 2 .0mol L ,B为 2 .2时Al13含量达到最高 ,占AlT 的 70 .2 % ,并在溶液中较稳定存在 .透射电镜实验结果表明 ,电解制备的PAC的粒度分布均匀 ,无团聚现象产生     

羟基聚合氯化铝的絮凝形态学

羟基聚合物的形态转化是无机高分子絮凝剂的核心问题，其形态学应包括研制，生产和应用三方面内容。铝的羟基聚合物形态主要有六员环连续模式和聚十三铝聚集模式两类论点。形态控制参数应以水解度和碱化度并用。     

Coagulation of micro-polluted Pearl River water with IPF-PACls

IntroductionThewaterqualityofnaturalriverisverycomplex,includingvariouskindsoforganic ,inorganicandbiologicalmatters,suchasthesolublemolecules,polymericmatters,colloids ,andsuspendedparticlessuchaslivebacteria ,algaeandalsoprotozoan (Tang,2 0 0 0 ) .Generally ,aquaticparticulatesaredispersivelysuspended ,ordepositintodiversesedimentsthroughadsorption ,aggregationandsedimentation.Furthermore ,theycanberesuspended ,transferredandconvertedundervariouswaterfluidconditions.Clearlydocumentedhistori…     

Coagulation of micro-polluted Pearl River water with IPF-PACIs

Water samples collected from early March 2001 to the end of April 2002 at the branch of Pearl River around the Guangzhou City were analyzed for its micro-polluted characteristics. The coagulation behavior of polyaluminum chlorides(PACIs) was then examined focusing on the effect of primary water quality and speciation distribution. The results showed that PACIs exhibit better coagulation efficiency than alum in accordance with the different speciation.The turbidity removal property of PACIs is evidently better than alum at low dosage. While in neutral zone(about 6.5--7.5), the turbidity removal of PACIs decreases owing to the restabilization of particles at higher dosage. The organic matters in raw water exhibit marked influence on coagulation. In acidic zone, organic matters complex with polymer species and promote the formation of flocs. With an increase in pH, the complexation of organics with polymer species gradually decreases, and the removal of organics mainly depends on adsorption. The effect is evidently improved with the raise of B value.     

Factors effecting aluminum speciation in drinking water by laboratory research

Effects of aluminum on water distribution system and human health mainly attribute to its speciation in drinking water. Laboratory experiments were performed to investigate factors that may influence aluminum speciation in water supply system. The concentration of soluble aluminum and its transformation among other aluminum species were mainly controlled by kinetics processes of related reactions. Total aluminum concentration had a notable e ect on the concentrations of mononuclear and soluble aluminum in the first 4 day; then its e ect became weak. At pH above 7.50, both fluoride and orthophosphate had little e ect on aluminum speciation; while, when the solution pH was below 7.50, the concentrations of mononuclear and soluble aluminum were proportional to the concentration of fluoride and inversely proportional to the concentration of orthophosphate. Both mononuclear and polynuclear silicic acids could complex with mononuclear aluminum by forming soluble aluminosilicates. In addition, the adding sequence of orthophosphate and aluminum into drinking water would also a ect the distribution of aluminum species in the first 4 day. In order to minimize aluminum bioavailability in drinking water, it was suggested that orthophosphate should be added prior to coagulant process, and that the concentrations of fluoride and silicic acids should be controlled below 2.0 and 25 mg/L, respectively, prior to the treatment. The solution pH in coagulation and filtration processes should be controlled in the range of 6.50–7.50.     

Morphology and electrical conductivity of PACS

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