Reaction mode between Si and Fe and evaluation of optimal species in poly-silicic-ferric coagulant

A kind of Fe-polysilicate polymer, poly-silicic-ferric （PSF） coagulant was prepared by co-polymerization （hydroxylation of mixture of Fe^3＋ and fresh polysilicic acid （PS））, in which PSF0.5, PSF1 or PSF3 denotes Si/Fe molar ratio of 0.5, 1 or 3, respectively. The effects of Si/Fe ratio and reaction time （co-polymerization time or aging time） on the reaction mode between Si and Fe were studies, and the optimal species of PSF was evaluated by pH change during the preparation of PSF and coagulation tests. The results showed that the characteristics of PSF are largely affected by both reaction time and Si/Fe ratio. PSF is found to be a essential complex of Si, Fe, and many other ions. The reaction mode between Si and Fe differs with various Si/Fe ratios. The pH of PSF0.5, PSF1 or PSF3 tended to be stable when reaction time is 10, 25 or 55 rain, respectively, which is almost consistent with the time reaching the relative stable morphology that is just the optimal species of higher coagulation efficiency. The optimal reaction time reaching optimal species can be evaluated by measuring the pH change during the polymerization process.

Synergistic coagulation of bauxite residue-based polyaluminum ferric chloride for dyeing wastewater treatment

Considering that Fe,Al elements in bauxite residue are active components for water purification,an effective polyaluminum ferric chloride(PAFC)coagulant derived from bauxite residue,with Fe2O3 content>5.1%,Al2O3%>6.5%,basicity>65%,was successfully prepared.The effect of as-prepared PAFC on the zeta potential for printing and dyeing wastewater was investigated.Comparing with polyferric chloride(PFC)and polyferric sulfate(PFS)for printing and dyeing wastewater treatment,prepared bauxite residue-based PAFC exhibited the optimal performance in the aspects of chromaticity and chemical oxygen demand(COD)removal rate.Furthermore,the combination of bauxite residue-based PAFC and PFS for synergy coagulation of such wastewater demonstrated an obvious positive effect.With the proportion between as-prepared PAFC and PFS to be 2.5:1,the COD of treated wastewater could be further reduced to meet the national level A standard of China,providing a promising route to solve the problem of substandard printing and dyeing sewage outfall by a simple coagulation strategy.

The gangue preparation coagulant （PFASS） experiment research and application

In order to design a new technological process system to take the polymeric ferric aluminum silicate sulfate（PFASS） and to apply it in wastewater processing, the chemical composition analysis was carried on to the Fuxin gangue, adopted the orthogonal experiment method to obtain optimum response condition of with the acid pickling taking the aluminum in the gangue and with alkali extracting taking the silicon in the gangue, The experiments indicate that the sample chemistry content which tests elect completely conform to the preparation inorganic polymer water treatment coagulant request standard. Used the polymeric ferric aluminum silicate sulfate results in which with the system take as the coagulant of treatment wastewater, used the mercerizing degree, the wastewater pH value, the coagulation time, the coagulant throws increment factors and so on to test and verify its influence on the waste water processing. The result indicates that by using this craft production PFASS in waste water processing, after the processed waste water achieves the emission standard, the processing effect is good.

Minimization of Residual Aluminum in Drinking Water by Using Nontoxic Polysilicate Coagulants

Two kinds of complex polysilicate coagulants-polysilicate iron PSI and polysilicate ferric aluminum PSFA were prepared. The polymerization processes of PSI and PSFA were investigated under various conditions. Experimental results show that the molecular weight(M.W.) of polysilicic acid PS and the molar ratio of Fe 3+ to SiO 2 are two of the most important factors for preparing high effective coagulants PSI and PSFA. It is shown that PSI and PSFA are not only high effective, nontoxic and cheap coagulants, but also effective for decreasing the dosage of aluminum salt. The mechanism of coagulation of PSI and PSFA is also discussed in this paper.

Investigating the Performance of the Coagulation Process When Using a Combination of Zinc Oxide Nanoparticles and Ferric Polysulfate

In this article, a new type of coagulant material has been investigated and the performance of the coagulation process using this type of coagulant was evaluated. This new type is a combination of zinc oxide nanoparticles and polyferric sulfate (ZnOPFS). The structure of zinc oxide nanoparticles was determined by spectroscopic, X-ray and electron microscopy methods, and based on this, it was determined that ZnOPFS is a complex and mixed compound that is mainly composed of zinc oxide nanoparticles and ferric sulfate. The effects of Zn/Fe (Zn/Fe) molar ratio and aging (time) on acidity and zeta potential were also evaluated using a specific method. The obtained results showed that in the simultaneous deposition process, zinc ions can prevent the formation of polyferric acid coagulation and subsequently improve the stability of ZnOPFS.

Removal of Turbidity and COD from a Synthetic Water Sample by Coagulation

The main objective of this research was to study the removal of turbidity and COD （chemical oxygen demand） from a synthetic water sample. The water sample was treated chemically by coagulation. Two inorganic coagulants were used, ferric chloride and the double salt potassium-aluminium sulphate. The optimum coagulant dosage and working pH were examined. The results for ferric chloride as coagulant showed that the maximum removal efficiency （%） of COD was achieved at pH 6 with a dosage of 100 mg-L-1 and the maximum removal efficiency （%） of turbidity at pH 5 with a dosage of 500 mg.L-1. For double salt, as coagulant, the maximum removal efficiencies （%） of COD and turbidity were achieved at pH 6 with a dosage of 3,500 mg.L-1. An extensive comparison with results from previous studies was also described in this research.

Pretreatment of Wastewater Streams from Petroleum/Petrochemical Industries Using Coagulation

Coagulation-flocculation processes using different types of conventional coagulants, namely, ferric chloride (FeCl3), aluminum sulfate (AL2(SO4)3·18H2O), lime and ferrous sulfate (FeSO4) were investigated using the Jar-test technique. A further aim is to determine the optimum conditions for the treatment of industrial wastewater effluents i.e. coagulant dosage, mixing rate, temperature and pH control. Under optimal condition of process parameters, coagulation/flocculation process was able to lower the turbidity well below the permissible level (1.8 NTU). The results indicate that ferric chloride had superior efficiency compared with other coagulants with efficient dose of 800 mg/l. The optimal initial pH of the effluents that enhanced the turbidity removal was 8.6. The temperature showed no significant effect on the turbidity removal.

聚合硫酸铁对水中聚乙烯微塑料的混凝效果与机理研究

以聚合硫酸铁(Polyferric Sulfate,PFS)和聚乙烯(Polyethylene,PE)微塑料分别作为混凝剂和去除对象,通过改变混凝剂投加量、微塑料粒径、溶液pH值及共存污染物等系统地研究不同条件下PFS对PE微塑料的去除性能。采用X射线光电子能谱(X-ray Photoelectron Spectroscopy,XPS)、傅里叶变换红外光谱(Fourier Transform Infrared Spectroscopy,FT-IR)、扫描电子显微镜(Scanning Electron Microscope,SEM)和Zeta电位分析方法初步探讨混凝机理。结果显示:当PFS投加质量浓度为10~550 mg/L时,PE微塑料的去除率随着PFS投加质量浓度的增加而呈升高趋势;加入表面活性剂及碱性条件下,PFS具有更好的混凝沉降性能;在小于500μm的粒径中,PE微塑料粒径为50~150μm时的去除率最高;当混凝剂投加质量浓度为550 mg/L,pH值为8时,去除率可达到98.0%,且优于铝系和天然混凝剂。在六价铬-微塑料共存体系中,微塑料的去除效果未受到显著影响。同时,混凝剂对六价铬的最大去除率可达到15.9%。混凝机理分析表明,电荷中和和吸附架桥作用为PFS对PE微塑料的主要混凝机制。

Preparation and coagulation efficiency of polyaluminium ferric silicate chloride composite coagulant from wastewater of high-purity graphite production

The aim of the present work was to produce a polyaluminium ferric silicate chloride （PAFSiC） coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride （PAC）. The PAFSiC coagulant was prepared by co-polymerization. The effects of （Al＋Fe）/Si molar ratio, OH/（Al＋Fe） molar ratio （i.e., γ value）, coagulant dosage and pH value of test suspension on the coagulation behavior of FAFSiC and the stability of the PAFSiC were also examined. Results showed that PAFSiC performed more efficiently than PAC in removing turbidity, chemical oxygen demand （COD）, and total phosphate （TP）. The PAFSiC with a γ value of 2.0 and （Al＋Fe）/Si ratio of 5 （PAFSiC 2.0/5） showed excellent coagulation effect for both turbidity and COD, while PAFSiC 1.0/5 was the best for TP. The optimum coagulation pH range of PAFSiC 2.0/5 was 5.0–9.0, slightly wider than that of PAC （6.0–8.0）. The process can be easily incorporated into high-purity graphite production plants, thereby reducing wastewater pollution and producing a valuable coagulant.

聚硅酸氯化铁锆混凝剂的制备及性能研究

为解决微污染水体中无机、有机污染物问题,开发绿色安全的混凝剂,以硅酸钠、氯化铁、氯化锆为原料制备聚硅酸氯化铁锆。选取高岭土和黄腐酸(FA)分别模拟微污染水体中无机和有机污染物,采用单因素法探究混凝剂的最佳制备条件和混凝条件。实验结果表明:在n(Fe)/n(Zr)为0.3、n(Fe+Zr)/n(Si)为1.0、碱化度为0.3的条件下聚硅酸氯化铁锆性能最好;在水样pH为7~8、投加量为2.5 mL/L、水样温度为15~20℃的条件下聚硅酸氯化铁锆效率最高,浊度和UV_(254)去除率分别为98.81%和83.58%。采用SEM、FTIR、XRD进行结构表征,可知聚硅酸氯化铁锆是聚硅酸和Fe^(3+)、Zr^(4+)络合成一种无特征衍射峰的无定型聚合物。

Effects of pH on coagulation behavior and floc properties in Yellow River water treatment using ferric based coagulants

Enhanced coagulation is one of the major methods to control disinfection by-products (DBPs) in water treatment process. Coagulation pH is an important factor that affects the enhanced coagulation. Recently, many studies focus on the coagulation effects and mechanisms, and few researchers studied the properties of flocs formed under different coagulation pH. Two inorganic polymer coagulants, polyferric silicate sulphate (PFSS) and polyferric sulphate (PFS), were used in Yellow River water treatment. The influence of pH on coagulation effect was investigated under the optimum dosage, and the results show that both coagulants gave excellent organism removal efficiency when pH was 5.50. According to the variation of zeta potential in coagulation process, coagulation mechanisms of the coagulants were analyzed. An on-line laser scatter instrument was used to record the development of floc sizes during the coagulation period. For PFSS, pH exerted great influence on floc growth rates but little influence on formed floc sizes. In PFS coagulation process, when pH was 4.00, PFS flocs did not reach the steady-state during the whole co-agulation period, while little difference was observed in floc formation when pH was 5.50 and above. The preformed flocs were exposed to strong shear force, and the variation of floc sizes was determined to evaluate the influence of pH on floc strength and re-growth capability. In comparison of the two coagulants, PFS flocs had higher floc strength and better recovery capability when pH was 4.00, while PFSS flocs had higher floc strength but weaker recovery capability when pH was 5.50 and above.

An enhanced coagulation using ferric chloride and poly-ferric chloride coagulant assisted by polyamidine:Performance and mechanisms

The deterioration of water caused by industrial production is a thorny problem.Solving the problem cogently through innovative coagulationstrategies has been recognized of important practical significance.In this work,a simple enhanced coagulation by using ferric chloride(FC)and poly-ferric chloride(PFC)coupled with polyamidine(PA)were tried to remove the toxic organics.The results shown that PA addition could obviously enhance coagulation performances of the iron-based coagulants.The synergic coagulation process and mechanism were studied and discussed in detail based on the coagulation behaviors,flocs properties,removal eficiency and zeta potentials.FC and PFC remove organics mainly through charge neutralization and adsorption-bridging,resulting in a good purification performance.While PA with a higher charge density showed better purification performance due to enhanced charge neutralization.It is worth mentioning that the addition of PA could make the coagulants adapt to a wider pH range,and remove the toxic organics more effectively.That is to say,the practical adaptability of the coagulant was enhanced.This work thus provides a simple strategy to effectively purify wastewater and further improve the water safety.

水处理混凝除钼研究进展与展望

随着工业的高速发展,钢铁、石油化工、电子等行业对金属钼的需求量日益增大,钼矿的大规模开采带来了严重的水污染问题。钼污染水体对人类健康和生态系统稳定造成了很大的威胁。在被钼污染的地下水、地表水和含钼废水处理中,经济且高效的混凝处理技术应用最为广泛。在分析钼的水污染现状和治理技术的基础上,全面综述了水处理混凝除钼技术中混凝剂、影响混凝除钼的主要因素、混凝除钼工艺及除钼机制的研究进展。铁盐是除钼应用最为广泛的混凝剂,在优化pH为4.0~5.0时,能够在复杂水基质条件下稳定去除钼污染物。水中碱度、硬度及磷酸盐、有机污染物对除钼的影响应该受到更多关注。多级混凝工艺在实际含钼水处理中效果显著。静电吸附、表面络合与网捕卷扫是混凝除钼的主要机制。此外,进一步对混凝除钼技术的科学研究和工程应用进行了总结和展望,可为钼的水污染控制提供有益参考。

聚合氯化铝铁的混凝性能

通过聚合氯化铝铁 (PAFC)对不同 p H值原水的混凝实验结果的比较 ,得出原水 p H值不同时 ,发挥最佳混凝效果的 PAFC的 Al/ Fe摩尔比也不同。实验室制聚合氯化铝 (PA C)、聚合氯化铁 (PFC)、PAFC混凝实验结果表明 :p H 6 .5时 ,PAFC(Al/ Fe=5 / 5 ,B=1.5 )的混凝效果最好 ,p H>6 .5时 ,则 PA FC(Al/ Fe=9/ 1,B=2 .0 )的混凝效果最好。

生活污水二级生物处理后的铁盐混凝除磷试验研究

以生活污水二级生物处理后的出水为研究对象 ,考察了铁盐对浓度在 2～ 4mg/L范围内的总磷的混凝去除效果及影响因素。结果表明 ,铁盐除磷的最佳 p H为 7.5～ 8;铁盐投加量较低时 ,适当提高 GT值可使总磷去除率增加 15 %～ 2 0 % ;在适当的混凝搅拌条件下 ,三价铁盐和聚合硫酸铁对总磷的去除率均在 70 %以上 ,混凝后过滤可使出水中总磷降至 0 .5 mg/L以下。

铝、铁共聚作用的化学特征及晶貌研究

通过对铝、铁水解共聚物的合成制备及其水解共聚合过程电位滴定的研究，并通过扫描电镜对其共聚物样品的的晶貌观测，ｎＡｌ／ｎＦｅ（Ａｌ（Ⅲ）与Ｆｅ（Ⅲ）摩尔比）的点能谱及结构组成的红外光谱测定，对铝铁共聚作用的化学特征及其晶形貌象、共聚作用进行了研究及讨论。

铁盐和铝盐混凝对水中天然有机物的去除特性研究

以三氯化铁和硫酸铝为研究对象,探讨了2种混凝剂对水中天然有机物的去除效果及特点.结果表明,低投量下,硫酸铝对天然有机物的去除效果要好于三氯化铁,混凝剂投量高于15 mg/L时,三氯化铁的效果较好.如混凝剂投量为10 mg/L时,硫酸铝和三氯化铁处理水的TOC分别为4.19 mg/L和9 mg/L;当混凝剂投量为20 mg/L时,TOC分别降至2.44 mg/L和1.69 mg/L.三氯化铁混凝后水的pH值降低幅度高于硫酸铝,形成的水解产物所带正电荷密度升高,水中有机物的质子化程度高,有利于对有机物的吸附去除.通过对UV254和SUVA的考察可知,三氯化铁对共轭结构及不饱和有机物的去除能力要高于硫酸铝.2种混凝剂对水中不同性质有机物的去除效果不同,三氯化铁对亲水性有机物去除效果较好,对小分子量有机物去除高于硫酸铝,如混凝剂投量为20 mg/L时,三氯化铁和硫酸铝对相对分子质量区间小于10 000的有机物去除率分别为16.4%和6.1%,而硫酸铝对大分子量有机物去除效率较高.

混凝剂投加量对水质及絮体尺寸变化特性的影响

以成都市府南河水为原水,通过小试分析了硫酸铝、氯化铁不同投加量下混凝工艺中浊度、UV254、pH、絮体平均粒径的变化情况,进而分析絮体尺寸特性与混凝剂投加量之间的关系。结果表明:硫酸铝投量对絮体平均粒径影响明显,投量为20～30mg/L时絮体平均粒径最大,投量为60mg/L时水质处理效果最好,此时絮体最大平均粒径为20～30mg/L投量20min内所形成的60%～70%。在低投量时(小于20mg/L),平均粒径增长缓慢,此后随着投量的增大,平均粒径达到稳定值所需的时间缩短。投加氯化铁时,其投加量对絮体粒径影响不明显,随着投量的增大,平均粒径达到稳定值所需的时间缩短。

铁盐和铝盐混凝剂对消毒副产物的控制作用及机制研究

以三氯化铁和硫酸铝为研究对象 ,探讨了两种混凝剂对三氯甲烷生成量的控制作用及控制机制 .结果表明 ,与硫酸铝相比 ,三氯化铁可以更好地控制三氯甲烷的生成量 ,对有机物的去除方面 ,也具有良好的效果 .E4/E6 变化表明 ,三氯化铁和硫酸铝对水中有机物的去除机制不同 ,硫酸铝主要去除水中大分子的有机物 ,三氯化铁更倾向于去除水中小分子有机物 ,而这些小分子有机物通常是消毒副产物的前体物 。