FeOCl层状材料及其插层化合物:结构、性质与应用

氧基氯化铁(FeOCl)是一种典型的Fe基层状材料,于20世纪30年代被发现,并于20世纪70年代起作为一种优异的插层主体在超分子插层化学领域进行了大量的研究.FeOCl的层状结构赋予了其远比传统铁(氢)氧化物更加灵活的调变空间,自2013年第一次发现FeOCl具有优异的固体Fenton活性以来,围绕FeOCl及其插层...     

油田作业废水絮凝过程中Zeta电位的研究

以川中矿区典型的压裂酸化废水为研究对象,考察了溶液pH值、无机混凝剂、有机高分子絮凝剂、以及无机混凝剂与有机高分子絮凝剂共同作用对废水Zeta电位的影响,从理论上对油田废水的絮凝特点进行了表征.实验结果证明:油田作业废水适合在酸性条件下进行絮凝处理;聚硅硫酸铁和阳离子有机高分子絮凝剂能使废水颗粒表面Zeta电位明显正移;当联合使用时,先加无机混凝剂,后加有机絮凝剂,能提高污水处理质量.     

Enhanced flocculation activity of polyacrylamide‐based flocculant for purification of industrial wastewater

The flocculation activity of commercially available anionic poly (acrylamide‐co‐acrylic acid), p (AAm‐co‐AA) has been significantly improved, without any inorganic coagulant aid. The effect of three types of surfactants, anionic sodium lauryl ether sulfate (SLES) (Palm Epimen), nonionic cocamide DEA, zwitterionic amphoteric Amphotensid B5, and one organic cation, trimethylammonium bromide (TAB) on coagulation/flocculation performance have been investigated. The performance has been analysed in terms of turbidity, total suspended solid (TSS), total iron (TI) content, and BTEX for treating two kinds of industrial wastewater, produced water (PW) and starch water. We have shown that adding a small amount of each of the studied surfactants, and especially cationic TAB, significantly increases the coagulation/flocculation performance without modifying pH levels. A combination of low dosage of flocculant (310 ppb) and TAB (310 ppb), after 5 minutes, presented 88%, 81%, and 62% reduction in turbidity, TSS, and TI content, respectively, whereas by using 5 ppm of flocculant alone (16 times more), only 76%, 75%, and 43% removal was obtained. The results reveal that TAB performs as an efficient coagulant booster. Compared with regular inorganic coagulants, it is more cost‐effective, reduces the consumption of treatment chemicals, and the pH‐dependency of contaminants removal.     

The coagulation of cellulose from anisotropic solutions in the NH3/NH4SCN solvent system

Coagulation of cellulose has been studied in cellulose/ammonia/ammonium thiocyanate anisotropic solutions. The effect of coagulation variables such as coagulant, bath temperature, and cellulose concentration on the coagulation process is reported. The coagulation rate was measured by microscopic observation of the moving boundary associated with coagulation. Results indicate that the coagulation rate increases with increasing cellulose concentration and bath temperature. Methanol has the highest coagulation power among the coagulants employed. Mass transfer rate difference and equilibrium swelling were also measured. The results on the mass transfer rate differences show that the mass transfer rate of NH₃/NH₄SCN is greater than those of the respective coagulants under all coagulation conditions. The equilibrium swelling decreases with increasing bath temperature and cellulose concentration.     

Removal of Congo Red dye from its aqueous solution using natural coagulants

The textile dyeing industry consumes large quantities of water and produces large volumes of wastewater from different processes in dyeing and finishing processes. The low-cost, easily available naturally prepared coagulants like Surjana seed powder (SSP), Maize seed powder (MSP) and Chitosan as an ideal alternative to recent expensive coagulant methods for Congo Red (CR) dye removal has been investigated in this study. Various process parameters like pH, coagulant dose, flocculation time and temperature and also its optimization were exploited. The maximum percentage CR removal was found to be 98.0, 94.5 and 89.4 for SSP, Chitosan and MSP, respectively, at pH 4.0, coagulant dose of 25 mg/l, flocculation time 60 min and temperature of 340 K. The Sludge Volume Index (SVI) and turbidity were calculated for these parameters including process optimization. SSP found more preferable for CR removal and Chitosan was a better coagulant, which corresponds to SVI than the other coagulants investigated.     

A study on the removal of organic substances from low-turbidity and low-alkalinity water with metal-polysilicate coagulants

The coagulants of poly-aluminum-chloride (PAC), poly-aluminum-silicate-chloride (PASiC) and poly-aluminum-ferric-silicate-chloride (PAFSiC) were prepared in this study to evaluate their coagulation efficiencies and mechanisms in synthetic low-turbidity and low-alkalinity water containing organic matter. The experimental results show that PASiC and PAFSiC could remove the kaolin turbidity of the synthetic water with or without salicylic acid present. On the other hand, when the synthetic water contained both kaolin and humic acid in low turbidity and alkalinity, PAC would remove the turbidity but charge reversal of the colloidal particles would occur easily. Also, effective coagulation was limited to a very narrow dosage range. Conversely, the dosage range for the effective coagulation of both PASiC and PAFSiC was wider, although a higher dosage was required to remove the turbidity of wastewater. Therefore, the effective removal of turbidity was not only related to the kind of coagulant, but also to the types of organic matter. The coagulants PASiC and PAFSiC, particularly, proved themselves to be superior to the PAC in the treatment of low-turbidity water.     

混凝沉淀法处理工业含氟废水的工艺研究

以半导体工业中的含氟废水为研究对象,采用混凝沉淀法对去除废水中氟离子进行了系统的工艺研究.以Ca(OH)2为沉淀剂,分别用聚合氯化铁(PFC)和聚合氯化铝(PAC)为混凝剂,并加入聚丙烯酰胺(PAM)助凝剂的方法,对药剂投加量、混凝剂种类、体系pH值、沉降时间等因素进行了实验探索.结果显示,PFC比PAC混凝效果好.当Ca(OH)2添加量为理论值的2.5倍,PFC用量为15mg/L,助凝剂PAM用量为4mg/L,体系的pH值在6～7时,其除氟效果最佳,此时废水中残留氟离子浓度可降低至5.5mg/L,远远低于国家规定的排放标准(10mg/L).     

Einlagerungsreaktionen von Biscyclopentadienyl-Vanadium und -Mangan mit Eisenoxidchlorid in etherischer Lösung

Intercalation Compounds of Manganocene and Vanadocene with FeOCl in Ether Solution The recently synthesized FeOCl intercalation compounds from Cp₂Mn and Cp₂V proved that in the case of the vanadium compounds the Fe³⁺ centers of the FeOCL host-lattice were partly reduced to Fe₂₊. In comparison to the bulk FeOCl, the central doublet in the Mößbauer spectra of the FeOCl intercalation compounds with NH₃, pyridine, 4-amino-pyridine, manganese and vanadium compounds indicates – with respect to the biscyclopentadienyl transition metal FeOCl intercalation compounds (M = Cr, Fe, Ni, Co) – a small chemical shift to higher energies and a degradation of the quadrupol splitting.     

Surfactant-assisted intercalation of crystal violet in layered γ-zirconium phosphate. Dye uptake from aqueous solutions

Batch intercalation experiments have carried out using γ-zirconium phosphate (γ-ZrP) and one of its cationic surfactant forms (γ-ZrP/SUR⁺) for removing crystal violet from aqueous solutions. The intercalation reactions have conducted along two different intervals of time (24 and 48?h). The intercalation process has followed up by X-ray diffractometry (XRD), UV–Visible and FT-IR spectrophotometries. Regarding γ-ZrP, XRD patterns show that obtained phases are impure, even after 48?h of the reaction time at a maximum dye loading of 18%. On the other side, γ-ZrP/SUR⁺ gives an impure phase after 24?h while a pure one (2.47?nm) is obtained after 48?h at a maximum dye loading of 19%. In both cases, the observed dye loading values are approximately equal to the one calculated by molecular modeling (ca. 20%). The used analysis approaches prove that dye uptake capacity is a function of the reaction time and inclination angle of the dye molecules inside the solid matrices, where the highest dye uptakes are observed with γ-ZrP and γ-ZrP/SUR⁺ after 48?h of the reaction time. This time (48?h) is long enough for the dye molecules to be sufficiently accumulated inside the interlayer regions, in such situation dye molecules are forced to stand up perpendicular to the inorganic layers. With respect to intercalation properties, the difference between γ-ZrP and γ-ZrP/SUR⁺ could be referred to the difference between their gallery heights (1.22 and 3.00?nm, respectively). The pre-intercalation of γ-ZrP with the surfactant molecules assists the inclusion and intercalation of the huge dye molecules into the interlayer region.     

Characterization of floc size and structure under different monomer and polymer coagulants on microfiltration membrane fouling

The characteristic of aggregates pre-coagulated by inorganic monomer alum, polymer aluminium chlorohydrate(ACH) and polyaluminium chloride(PACl) coagulants impose major impact on the removal of humic acids (HAs) and the reduction of microfiltration (MF) membrane fouling. The fractal dimension of flocs formed by ACH and PACl is higher than that by monomer alum, indicating Keggin structure produced by polymer coagulants is much more compact compared with hexameric ring structure of alum hydrolysis species. Correspondingly, cake layer specific resistance is far higher and the MF membrane flux deteriorates much more severely when pre-coagulated by ACH and PACl than by alum. Moreover, the higher basicity contains in PACls, the cake layer fouling is more serious for producing more proportion of dense hydrolysis species Al₁₃. Thus, the polymer coagulant ACH and PACl seems not adapt to the pre-coagulation–MF process for cake layer resistance increase two to three times although they save 60–70% dose in comparison with alum for HAs removal. Additionally, for three Al-based coagulants under sweep coagulation condition, insufficient dose result in lower HAs removal and produce more small particles caused higher cake layer specific resistance according to Carman–Kozeny relationship. On the other hand, coagulant hydrolysis species as direct contaminant loading aggravated cake resistance on the MF membrane when overdosed. The optimum dose should keep the minimum to provide better HAs removal efficiency, and produce lower cake layer specific resistance and higher membrane filterability for pre-coagulation–MF hybrid process.     

Coagulation-crossflow microfiltration of domestic wastewater

The effect of using alum, polyaluminum silicate sulfate (PASS), and lime as coagulants on the performance of crossflow microfiltration of domestic wastewater was investigated. The primary membrane used throughout the study was made of woven polyester, while the dynamic membrane was formed by circulating MnO₂ precipitate. Slug doses of the coagulants were added to the circulation tank of the experimental setup at the beginning of each run. Doses of 20 to 120 mg/l of alum were investigated at pH of 7. The results showed an improvement in flux values with the increase in alum dose until an optimum dose beyond which no significant improvement was seen. Flux improvement was attributed to the agglomeration of particles which can be easily swept away by the shearing actions created by the crossflow velocity. Permeate quality was not found to be significantly affected by the increase in alum dose. PASS, which is an aluminum salt, was seen to behave in the same manner as alum when used as a coagulant. Lime was not found to be a suitable coagulant under these conditions.     

Dye fixation and decolourization of vinyl sulphone reactive dyes by using dicyanidiamide fixer in the presence of ferric chloride

A synthetic polymer was synthesized and used for the improvement of dyeing properties as well as decolorization of textile waste water. Two dyes were selected having anthraquinone based Remazol Blue R and azo based Remazol Red RB. It was observed that the synthetic polymer can be used as fixer for the fixation of dye by crosslinking between dye and fibre, which not only improves the dyeing properties but also helpful to coagulate the colour after dyeing. By single point method the concentrations of synthetic polymer were calculated in residual after dyeing. It was examined that the residual synthetic polymer is helpful in colour removal efficiency by coagulation of polymer with dye to form heavy molecules which settle down and decolorization occurred. Colour removal efficiency was found dependents on pH, concentration of synthetic polymer and inorganic coagulant.     

湿式氧化用于染料废水脱色:过去20年回顾（英文）简

Wet air oxidation (WAO), a liquid phase reaction between organic materials in water and oxygen, is one of the most economical and technologically viable advanced oxidation processes for wastewater treatment, particularly toxic and high organic content wastewater. WAO is the liquid phase oxidation of organics or oxidizable inorganic components at elevated temperatures (125-320℃) and pressures (0.5-20 MPa) using gaseous oxygen (or air) as oxidant. In the past two decades, the WAO process was widely studied and applied in the treatment of dye wastewater. Compared to conventional WAO, catalytic WAO processes have higher efficiency and use moderate reaction conditions. The catalysts included homogenous and heterogeneous types. The key points that need to be solved are recycling of homogenous catalysts and better stability of heterogeneous catalysts. In the present review, the technological processes are first introduced, then some research history and hotspots of WAO research are presented, and finally, its application in the treatment of dye wastewater in the past two decades is summarized to reveal the impressive changes in modes, trends, and conditions used. The application includes model pollutant studies and wastewater tests.     

Cationic Polymers as Organic Coagulants in Water Treatment at Heat and Electric Power Plants

The efficiency of water treatment with organic coagulants (cationic polymers) and calcium hydroxide (alkalizing agent) in combination with iron(II) sulfate (mineral coagulant) was studied as influenced by the nature and concentration of an organic coagulant and concentration of a mineral coagulant.     

Coagulation behaviors and in-situ flocs characteristics of composite coagulants in cyanide-containing wastewater: Role of cationic polyelectrolyte

In this paper,composite coagulants(PFS,PFSC05,PFSC1 and PFSC5),prepared by mixing polyferric sulfate(PFS)and cationic polyelectrolyte(CP)coagulants with different weight percent(Wp)of CP(Wp=0%,0.5%,1%and 5%,respectively),were adopted to treat cyanide-containing wastewater.PFSC5 exhibited superior coagulation performances at optimal conditions:the removal of total cyanide(TCN)and chemical oxygen demand(COD)was 95%–97%and 50%–55%,respectively.The effects of CP on the properties and structure of flocs were investigated by laser diffraction instrument and small-angle laser light scattering(SALLS),respectively.The results show that the flocs of PFSC5 have higher growth rate,higher strength factor and lower recovery factor than other flocs.They are also much denser and more uniform owing to the higher fractal dimension(Df)and less microflocs(10–100 m).Furthermore,the dense structure of the PFSC5 flocs can be restored after shear and is more resistant to hydraulic conditions.Particularly,detailed morphology evolution of the flocs was in-situ detected by on-line particle imaging.Due to strong ionic strength in wastewater,the CP in PFSC5 plays a significant role of adsorption,while the main mechanism of CP is electrostatic patch aggregation during the PFSC05 systems.     

OKRA (HIBISCUS ESCULENTUS) AND FENUGREEK (TRIGONELLA FOENUM GRACEUM) MUCILAGE: CHARACTERIZATION AND APPLICATION AS FLOCCULANTS FOR TEXTILE EFFLUENT TREATMENTS

The use of new food grade polysaccharides (mucilage) obtained from Hibiscus esculentus and Trigonella foenum graceum,commonly called Okra and Fenugreek,respectively,as flocculants was described.These polysaccharides were used for removal of solids (suspended solids (SS) and total dissolved solids (TDS)) and dyes from real textile effluents and aqueous solutions of different class of synthetic dyes.Influences of varying polysaccharide concentration,contact time and pH on removal of pollutant from the text...     

OKRA(HIBISCUS ESCULENTUS)AND FENUGREEK(TRIGONELLA FOENUM GRACEUM)MUCILAGE:CHARACTERIZATION AND APPLICATION AS FLOCCULANTS FOR TEXTILE EFFLUENT TAEATMENTS

The use of new food grade polysaccharides (mucilage) obtained from Hibiscus esculentus and Trigonella foenum graceum,commonly called Okra and Fenugreek,respectively,as flocculants was described.These polysaccharides were used for removal of solids (suspended solids (SS) and total dissolved solids (TDS)) and dyes from real textile effluents and aqueous solutions of different class of synthetic dyes.Influences of varying polysaccharide concentration,contact time and pH on removal of pollutant from the textile wastewater were investigated.Results showed that polysaccharides (mucilage) obtained from Okra and Fenugreek were capable of removing 90%-94% of SS,30%-44% of TDS and 30%-35% of dye using a very low concentration of polysaccharide.X-ray diffraction (XRD) patterns of solid waste material obtained before and after the treatment with polysaccharides were used as a supportive evidence to explain the mechanism of flocculation.     

Investigation of the dynamics of poly(ether sulfone) membrane formation by immersion precipitation

Cast‐leaching experiments were carried out to investigate the dynamics of membrane formation by immersion precipitation, with an emphasis on the outflow of the solvent from casting solutions during the phase‐separation process. The casting solutions, consisting of poly(ether sulfone) as the polymer, N‐methyl‐2‐pyrolidone as the solvent, and water (H₂O), isopropyl alcohol, 1‐butanol, and diethylene glycol as nonsolvent additives (NSAs), were immersed in a coagulation bath. Two thermodynamically vastly different coagulants? H₂O, a strong coagulant, and ethylene glycol, a weak coagulant—were used to study the effect of the coagulant on the dynamics of membrane formation. The results showed that the outflow of the solvent during the initial stage of membrane formation was controlled by Fickian diffusion within the extremely wide range of conditions studied, that is, polymer concentrations of 10–38%, approaching ratios of 0–0.95, and thermodynamically vastly different NSAs and coagulants. The role of the initial state of the membrane‐forming solution, especially the conformational state of macromolecules in the membrane‐forming process, was examined. In contrast to those works on the behavior of small molecules, an attempt was made to qualitatively interpret membrane formation from the viewpoint of macromolecules. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 498–510, 2005     

Chitosan for coagulation/flocculation processes - An eco-friendly approach

Chitosan is a partially deacetylated polymer obtained from the alkaline deacetylation of chitin, a biopolymer extracted from shellfish sources. Chitosan exhibits a variety of physico-chemical and biological properties resulting in numerous applications in fields such as cosmetics, biomedical engineering, pharmaceuticals, ophthalmology, biotechnology, agriculture, textiles, oenology, food processing and nutrition. This amino-biopolymer has also received a great deal of attention in the last decades in water treatment processes for the removal of particulate and dissolved contaminants. In particular, the development of chitosan-based materials as useful coagulants and flocculants is an expanding field in the area of water and wastewater treatment. Their coagulation and flocculation properties can be used to remove particulate inorganic or organic suspensions, and also dissolved organic substances. This paper gives an overview of the main results obtained in the treatment of various suspensions and solutions. The effects of the characteristics of the chitosan used and the conditions in solution on the coagulation/flocculation performance are also discussed.     

Modification of crystallinity and pore size distribution in coagulated cellulose films

In this study the effects of altering the coagulation medium during regeneration of cellulose dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate, were investigated using solid-state NMR spectroscopy and NMR cryoporometry. In addition, the influence of drying procedure on the structure of regenerated cellulose was studied. Complete conversion of the starting material into regenerated cellulose was seen regardless of the choice of coagulation medium. Coagulation in water predominantly formed cellulose II, whereas coagulation in alcohols mainly generated non-crystalline structures. Subsequent drying of the regenerated cellulose films, induced hornification effects in the form of irreversible aggregation. This was indicated by solid-state NMR as an increase in signal intensity originating from crystalline structures accompanied by a decrease of signal intensity originating from cellulose surfaces. This phenomenon was observed for all used coagulants in this study, but to various degrees with regard to the polarity of the coagulant. From NMR cryoporometry, it was concluded that drying induced hornification generates an increase of nano-sized pores. A bimodal pore size distribution with pore radius maxima of a few nanometers was observed, and this pattern increased as a function of drying. Additionally, cyclic drying and rewetting generated a narrow monomodal pore size pattern. This study implies that the porosity and crystallinity of regenerated cellulose can be manipulated by the choice of drying condition.