Properties and coagulation mechanisms of polyferric silicate sulfate with high concentration

Polyferric silicate sulfate （PFSS） with high concentration was prepared using the composite-poly method. The coagulation properties and mechanisms of this new complex were probed using TEM, Fe-Ferron timed complex-colorimetric method, and infrared spectrum method. The results showed that the flocculating effect of polyferric silicate sulfate had an advantage over polyferric sulfate （PFS）, as the optimum coagulation effect could be obtained when the Si/Fe mole ratio was 0.75 in accordance with its macrostructure of PFSS. According to the Fe-Ferron timed complex-colorimetric method, the Si species was mainly Sic, whereas, the Fe species were Fea and Fec in the copolymerization system. The infrared spectra indicated that the structure of these new flocculants was formed by polymers, mainly by olation, which was different from polyferric sulfate, and the vibration of M-OH-M of around 1100 cm^-1, also proved that there existed Fe-OH-Fe and its polymers in some forms.

Influence of coagulation mechanisms and floc formation on filterability

Minimizing particles in water is a key goal for improving drinking water quality and safety.The media filtration process,as the last step of the solid–liquid separation process,is largely influenced by the characteristics of flocs,which are formed and controlled within the coagulation process.In a laboratory-based study,the impacts of the physical characteristics of flocs formed using aluminum sulfate on the filtration treatment of two comparative water samples were investigated using a photometric dispersion analyzer and a filterability apparatus.In general,the optimum dosage for maximizing filterability was higher than that for minimizing turbidity under neutral p H conditions.For a monomeric aluminum-based coagulant,the charge neutralization mechanism produced better floc characteristics,including floc growth speed and size,than the sweep flocculation mechanism.In addition,the charge neutralization mechanism showed better performance compared to sweep flocculation in terms of DOC removal and floc filterability improvement for both waters,and showed superiority in turbidity removal only when the raw water had high turbidity.For the different mechanisms,the ways that floc characteristics impacted on floc filterability also differed.The low variation in floc size distribution obtained under the charge neutralization mechanism resulted in the flocs being amenable to removal by filtration processes.For the sweep flocculation mechanism,increasing the floc size improved the settling ability of flocs,resulting in higher filter efficiency.

Rational Design of a High-Performance KMnO_(4)-Fe(Ⅱ)-Si Coagulant for Dye Removal

A new ternary coagulant polysilicate ferromanganese(PSFM),composed of Fe,Mn and Si,was designed.Its coagulation performance for dye removal was investigated systematically together with the impact of several key operational parameters.The experimental results indicate that an excellent coagulation efficiency with higher than 95%color removal and higher than 94%total organic carbon(TOC)removal can be obtained at an optimized molar ratio of Si∶Fe∶Mn(5∶5∶1).The coagulation performance of PSFM coagulant was studied comparatively with other conventional coagulants,e.g.poly aluminium chloride(PAC),Al_(2)(SO_(4))_(3)and FeCl_(3).Additionally,various characterization techniques were applied to get detailed morphological and compositional information of PSFM coagulants.Furthermore,the underlying mechanism for improved coagulant performance was proposed based on these results.These results have exemplified quantitatively that PSFM coagulant exhibits a great potential as a promising material for application in various environmental fields.

Application and mechanism of polysaccharide extracted from Enteromorpha to remove nano-ZnO and humic acid in coagulation process

Enteromorpha polysaccharide （Ep） extracted from alga a novel green coagulant aid for nanoparticles （NPs） and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration of Ep with polyaluminum chloride （PAC-Ep） coagulants exhibited higher coagulation performance than that of the polyaluminum chloride （PAC） because of the negatively charged NPs suspension and humic aid （HA） solution. Significant high removal efficiencies of dissolved organic matter （94.1%）, turbidity （99.3%） and Zn ions （69.3%） were achieved by the PAC-Ep coagulants. The dual-coagulation properties of PAC-Ep for different pollutants was based on multiple mechanisms, including （i） AI^3＋ charge neutralization; （ii） hydroxy aluminum hydroxyl bridging formed polynuclearhydroxy complexes bridge and sweep colloidal particles; （iii） adsorption and bridging of Ep chain for the NPs and heavy metal ions. Results indicated that the destabilization of colloid was induced by the coexisting HA and higher removal was achieved as ions adsorption was enhance in the presence of HA complexation. On the basis of that, the extraction of polysaccharide is a promising candidate for its high coagulation performance in water treatment.

Molecular mechanism of microRNA125 regulating human coagulation factor IX gene with nonsense mutation

Objective To construct human coagulation factorⅨmini-gene(Mini-h F9)and some nonsense mutants,detect the levels of the Mini-h F9 mRNA,and analyze the molecular mechanism of microRNA125 regulating F9gene with nonsense mutation.Methods Three nonsense mutants were obtained by using PCR mutagenesis to ana-

A bioactive nanocomposite sponge for simultaneous hemostasis and antimicrobial therapy

Uncontrollable bleeding and bacterial infections are the major reasons for the high mortality of post-traumatic.In this study,a composite hemostatic chitosan sponge CaO_(2)@SiO_(2)/CS was prepared by combining a novel core-shell inorganic nano hemostatic CaO_(2)@SiO_(2)nanoparticles with carboxylated chitosan,which presents a multi-layered structure with a rough and hydrophilic surface for rapid absorption of blood.When the CaO_(2)@SiO_(2)nanoparticles in the CaO_(2)@SiO_(2)/CS come into contact with blood,the silanol group on its surface and the released H_(2)O_(2)and Ca2+can recruit and activate platelets,while generating fibrin clots and activating the endo-exogenous coagulation cascade reaction to achieve rapid clotting.The H_(2)O_(2)released from CaO_(2)@SiO_(2)shows the antimicrobial capacity and stimulates the production of tissue factors by endothelial cells.Meanwhile,the silica coating reduces the cytotoxicity of bare CaO_(2),thus reducing the risk of secondary bleeding at the site of vascular injury.CaO_(2)@SiO_(2)/CS(48 s)showed a 1.83-and 2.52-fold reduction in hemostasis time compared to commercial gelfoam and CS in a femoral artery hemorrhage model.This study illustrates the hemostatic mechanism of CaO_(2)@SiO_(2)and provides a reference for the development of clinical biomedical inorganic hemostatic materials.

Efficient removal of algae and turbidity from water by a composite coagulant composed of a cationic starch and attapulgite

Algae and suspended colloidal particles produced high turbidity in water,weakened water purification,and threatened the safety of the water supply.In this study,a series of composite coagulants(atp-st-CTA)composed of a cationic starch(st-CTA)and attapulgite(ATP)with different fed mass ratios were fabricated by a simple method to coagulate kaolin suspension with initial turbidity of 80.0 NTU and Chlorella suspension with 0.25 mg/L of chlorophyll a(chla),respectively.Fourier transform infrared spectroscopy and scanning electron microscopy investigated the structural characteristics of atp-st-CTA.The maximum turbidity and chla removal rates of atp-st-CTA were 92.2%and 100.0%,respectively,at natural pH conditions.The effects of the fed mass ratio of st-CTA to ATP in the composites,dose,pH,and coexisting humic acid on the coagulation performance of atp-st-CTA were comprehensively investigated.Based on the apparent coagulation behaviors,the zeta potentials of the supernatants after coagulation,and the flocs properties,the coagulation mechanisms of atp-st-CTA were discussed in detail.The complete charge neutralization due to st-CTA and the enhanced sedimentation by ATP synergistically removed turbidity and algae from the water efficiently.In short,atp-st-CTA as a talented material has a notable prospect in applications of water treatment owing to its advantages of environmental friendliness,low cost,and high efficiency.

Comparison of the effects of aluminum and iron(Ⅲ)salts on ultrafiltration membrane biofouling in drinking water treatment

Coagulation plays an important role in alleviating membrane fouling, and a noticeable problem is the development of microorganisms after long-time operation, which gradually secrete extracellular polymeric substances（EPS）. To date, few studies have paid attention to the behavior of microorganisms in drinking water treatment with ultrafiltration（UF）membranes. Herein, the membrane biofouling was investigated with different aluminum and iron salts. We found that Al_2（SO_4）_3·18 H_2O performed better in reducing membrane fouling due to the slower growth rate of microorganisms. In comparison to Al_2（SO_4）_3·18H_2O,more EPS were induced with Fe_2（SO_4）_3·x18H_2O, both in the membrane tank and the sludge on the cake layer. We also found that bacteria were the major microorganisms, of which the concentration was much higher than those of fungi and archaea. Further analyses showed that Proteobacteria was dominant in bacterial communities, which caused severe membrane fouling by forming a biofilm, especially for Fe_2（SO_4）_3·x18H_2O. Additionally, the abundances of Bacteroidetes and Verrucomicrobia were relatively higher in the presence of Al_2（SO_4）_3·18 H_2O,resulting in less severe biofouling by effectively degrading the protein and polysaccharide in EPS. As a result, in terms of microorganism behaviors, Al-based salts should be given preference as coagulants during actual operations.