Flocculation mechanism by a novel combined aluminum–ferrous–starch flocculant (CAFS)

2012 ◽  
Vol 65 (12) ◽  
pp. 2169-2174 ◽  
Author(s):  
Qintie Lin ◽  
Hanping Pan ◽  
Haoping Huang ◽  
Guoguang Liu ◽  
Guangcai Yin
Keyword(s):  
Molecular Weight ◽  
Water Treatment ◽  
Zeta Potential ◽  
Charge Density ◽  
High Molecular Weight ◽  
Ph Value ◽  
Dynamic Changes ◽  
Flocculation Mechanism ◽  
Linear Chains ◽  
High Charge Density

A combined flocculant (CAFS) was prepared with Al2(SO4)3·18H2O, FeSO4·7H2O and starch. The flocculation mechanism of reactive brilliant red X-3B was studied. The results showed that CAFS was a cationic polymeric flocculant with high charge density, and its mesh starch chains grafted polyaluminum and polyferrous. At the preliminary stage, the main flocculation mechanism was adsorption and charge neutralization. At a later stage, the high molecular weight and flexible linear chains of CAFS initiated bridge-aggregation and sweep-flocculation. Moreover, the zeta potential and dynamic changes of flocs were closely related to flocculant dosages and the pH. The optimum dosage of CAFS and pH value were 0.990 mg/L and 5.0. Taken together, these results suggested CAFS as a novel flocculant in water treatment, with good results for the studied conditions.

scholarly journals Dynamic changes in optical and chemical properties of tar ball aerosols by atmospheric photochemical aging

2019 ◽  
Vol 19 (1) ◽  
pp. 139-163 ◽  
Author(s):  
Chunlin Li ◽  
Quanfu He ◽  
Julian Schade ◽  
Johannes Passig ◽  
Ralf Zimmermann ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Light Absorption ◽  
Chemical Properties ◽  
Oh Radical ◽  
Dynamic Changes ◽  
Photochemical Process ◽  
Tar Balls ◽  
Photochemical Aging ◽  
And Chemical Properties

Abstract. Following wood pyrolysis, tar ball aerosols were laboratory generated from wood tar separated into polar and nonpolar phases. Chemical information of fresh tar balls was obtained from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and single-particle laser desorption/resonance enhanced multiphoton ionization mass spectrometry (SP-LD-REMPI-MS). Their continuous refractive index (RI) between 365 and 425 nm was retrieved using a broadband cavity enhanced spectroscopy (BBCES). Dynamic changes in the optical and chemical properties for the nonpolar tar ball aerosols in NOx-dependent photochemical process were investigated in an oxidation flow reactor (OFR). Distinct differences in the chemical composition of the fresh polar and nonpolar tar aerosols were identified. Nonpolar tar aerosols contain predominantly high-molecular weight unsubstituted and alkyl-substituted polycylic aromatic hydrocarbons (PAHs), while polar tar aerosols consist of a high number of oxidized aromatic substances (e.g., methoxy-phenols, benzenediol) with higher O : C ratios and carbon oxidation states. Fresh tar balls have light absorption characteristics similar to atmospheric brown carbon (BrC) aerosol with higher absorption efficiency towards the UV wavelengths. The average retrieved RI is 1.661+0.020i and 1.635+0.003i for the nonpolar and polar tar aerosols, respectively, with an absorption Ångström exponent (AAE) between 5.7 and 7.8 in the detected wavelength range. The RI fits a volume mixing rule for internally mixed nonpolar/polar tar balls. The RI of the tar ball aerosols decreased with increasing wavelength under photochemical oxidation. Photolysis by UV light (254 nm), without strong oxidants in the system, slightly decreased the RI and increased the oxidation state of the tar balls. Oxidation under varying OH exposure levels and in the absence of NOx diminished the absorption (bleaching) and increased the O : C ratio of the tar balls. The photobleaching via OH radical initiated oxidation is mainly attributed to decomposition of chromophoric aromatics, nitrogen-containing organics, and high-molecular weight components in the aged particles. Photolysis of nitrous oxide (N2O) was used to simulate NOx-dependent photochemical aging of tar balls in the OFR. Under high-NOx conditions with similar OH exposure, photochemical aging led to the formation of organic nitrates, and increased both oxidation degree and light absorption for the aged tar ball aerosols. These observations suggest that secondary organic nitrate formation counteracts the bleaching by OH radical photooxidation to eventually regain some absorption of the aged tar ball aerosols. The atmospheric implication and climate effects from tar balls upon various oxidation processes are briefly discussed.

Study on Effect and Mechanism of Chitosan Coagulation Aid in Flocculation Treatment of Water Supply

2012 ◽  
Vol 433-440 ◽  
pp. 1857-1863
Author(s):  
Bing Tao Liu ◽  
Wei Wu ◽  
Hai Yang Cong
Keyword(s):  
Molecular Weight ◽  
Image Analysis ◽  
Fractal Dimension ◽  
Electron Microscope ◽  
Zeta Potential ◽  
Ph Value ◽  
Yellow River ◽  
Image Analysis System ◽  
Raw Water ◽  
Analysis System

The aim of this work is to remove residual turbidity and index of Potassium permanganate of the drinking water by PAC/Chitosan coagulation treatment. The experiments were performd the efficiency of coagulation by PAC/Chitosan at different chitosan dosages , molecular weight and pH value. Zeta potential instrument and Nikon electron microscope were used to test Zeta potential and observe flocs morphology. It turn out that Chitosan enhance the flocculation treatment of the surface water of raw water of Yellow River by polymeric aluminum chloride (PAC)when PAC dosage is 35 mg•l-1 and Chitosan is 0.15 mg•l-1 and infer coagulation aid mechanism was interpartical bridging rather than the electrical neutralization. Microscope and image analysis system of flocs morphology show that fractal dimension of morphology of PAC and PAC/Chitosan were 1.294,1.385, respectively.

Influence of Zeta Potential on the Lubrication Between Ultra-High Molecular Weight Polyethylene and CoCrMo Alloy

2000 ◽  
Author(s):  
Toshio Kitano
Keyword(s):  
Molecular Weight ◽  
Zeta Potential ◽  
High Molecular Weight ◽  
Friction And Wear ◽  
Long Term Results ◽  
Cocrmo Alloy ◽  
Total Replacement ◽  
Lubrication Condition ◽  
Ultra High Molecular Weight

Abstract Zeta potential is the potential that is related to the electric charge of the surface. Zeta potential influences tribological surface phenomenons. In the field of Orthopaedic surgery, osteolysis due to wear debris is one of the most difficult complications following total joint arthroplasty. Improvement of long term results and decrease of the revision rate demand that the lubrication mechanism of total replacement joint be revealed and friction and wear of surface be reduced. The purpose of this study is to clarify the correlation between zeta potential of ultra-high molecular weight polyethylene (UHMWPE) and friction in total replacement joint under boundary lubrication condition and to answer the effect of glycoprotein on total replacement joint.

The effectiveness of humic acids coagulation with the use of cationic polyacrylamides

2011 ◽  
Vol 63 (9) ◽  
pp. 1944-1949 ◽  
Author(s):  
B. Libecki
Keyword(s):  
Molecular Weight ◽  
Charge Density ◽  
Humic Acids ◽  
Colloidal Particles ◽  
Optimal Dose ◽  
Test Method ◽  
Jar Test ◽  
Effective Removal ◽  
High Charge Density ◽  
Proportional Relationship

The chemical coagulation process is a popular method for eliminating the precursors of disinfection by-products. This study presents the results of a laboratory experiment which investigates the use of cationic polyacrylamide copolymers (CPAMs) as primary coagulants in the purification of solutions containing humic acids (HA). A number of polymers with various molecular weight and charge density were tested. The optimal doses were determined by colloidal titration. The effectiveness of coagulation-flocculation was determined by jar test method. The post-coagulation suspension was separated by filtration through cellulose filter paper. The experiment showed that charge neutralization destabilizes organic colloidal particles. An inversely proportional relationship was observed between the optimal dose and polymer charge density. The effectiveness of UV254 reduction (52–81%) and colour removal (51–88%) was determined by the effectiveness of filtration in removing post-coagulation turbidity, as well as by the type of applied polymer. The results of the study suggest that the use of CPAMs with high charge density and low molecular weight enables effective removal of humic acids from water in the coagulation and filtration process.

The effectiveness of humic acid coagulation with the use of cationic polyacrylamides

2010 ◽  
Vol 61 (6) ◽  
pp. 1555-1560 ◽  
Author(s):  
B. Libecki
Keyword(s):  
Molecular Weight ◽  
Charge Density ◽  
Humic Acids ◽  
Colloidal Particles ◽  
Optimal Dose ◽  
Test Method ◽  
Jar Test ◽  
Effective Removal ◽  
High Charge Density ◽  
Proportional Relationship

The chemical coagulation process is a popular method for eliminating the precursors of disinfection by-products. This study presents the results of a laboratory experiment which investigates the use of cationic polyacrylamide copolymers (CPAMs) as primary coagulants in the purification of solutions containing humic acids (HA). A number of polymers with various molecular weight and charge density were tested. The optimal doses were determined by colloidal titration. The effectiveness of coagulation-flocculation was determined by jar test method. The post-coagulation suspension was separated by filtration through cellulose filter paper. The experiment showed that charge neutralization destabilizes organic colloidal particles. An inversely proportional relationship was observed between the optimal dose and polymer charge density. The effectiveness of UV254 reduction (52–81%) and colour removal (51–88%) was determined by the effectiveness of filtration in removing post-coagulation turbidity, as well as by the type of applied polymer. The results of the study suggest that the use of CPAMs with high charge density and low molecular weight enables effective removal of humic acids from water in the coagulation and filtration process.

scholarly journals Dynamic changes in plasma total and high molecular weight adiponectin levels in acute heart failure

2011 ◽  
Vol 58 (2) ◽  
pp. 181-190 ◽  
Author(s):  
Takahiro Ohara ◽  
Kazuhiko Hashimura ◽  
Masanori Asakura ◽  
Akiko Ogai ◽  
Makoto Amaki ◽  
...  
Keyword(s):  
Heart Failure ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Acute Heart Failure ◽  
Dynamic Changes ◽  
High Molecular Weight Adiponectin

Concrete Superplasticizer Prepared from Catalytic Oxidation of Lignosulfonate

2012 ◽  
Vol 424-425 ◽  
pp. 1088-1092 ◽  
Author(s):  
Zhe Wang ◽  
Jing Wen Xue ◽  
Ji Shi Zhang ◽  
Wen Xia Liu
Keyword(s):  
Molecular Weight ◽  
Catalytic Oxidation ◽  
High Molecular Weight ◽  
Cement Paste ◽  
Oxidation Reaction ◽  
Ph Value ◽  
Oxidative Degradation ◽  
Main Reaction ◽  
Sulfonic Group

Bamboo lignosulfonate was modified under the role of H2O2 and catalyst in order to improve the dispersing property of lignosulfonate. Results show that the amount of H2O2 and pH value have strong influences on characteristics of lignosulfonate. Cement paste fluidity of lignosulfonate modified at pH5 and 11% H2O2 is 178mm, which is 68% higher than that of unmodified lignosulfonate. Both of oxidative degradation and condensation occur during catalytic oxidation reaction, but oxidation is the main reaction when high amount of H2O2 is applied. The structure of lignosulfonate has some relationship to water reducing property. High molecular weight, high carboxylic content and proper sulfonic group content are the main reasons that enhance water reducing property of lignosulfonate.

scholarly journals Dynamic changes of optical and chemical properties of tar ball aerosols by atmospheric photochemical aging

2018 ◽  
Author(s):  
Chunlin Li ◽  
Quanfu He ◽  
Julian Schade ◽  
Johannes Passig ◽  
Ralf Zimmermann ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Refractive Index ◽  
High Molecular Weight ◽  
Oxidation State ◽  
Chemical Properties ◽  
Dynamic Changes ◽  
Photochemical Process ◽  
Tar Balls ◽  
Photochemical Aging ◽  
And Chemical Properties

Abstract. Following wood pyrolysis, tar ball aerosols were generated from wood tar separated into polar and nonpolar phases. Chemical information of fresh tar balls was obtained from the high-resolution time-of-flight aerosol mass spectrometer (HiRes-ToF-AMS) and laser desorption/resonance enhanced multiphoton ionization mass spectrometry (LD-REMPI-MS), and their refractive index between 365 and 425 nm were retrieved using a broadband cavity enhanced spectroscopy. Dynamic changes of the optical and chemical properties for the nonpolar tar ball aerosols in NOx-dependent photochemical process were investigated in an oxidation flow reactor (OFR). Distinct differences in the chemical composition of the polar and nonpolar tar aerosols were identified. Nonpolar tar aerosols contain predominantly high-molecular weight unsubstituted and alkyl-substituted polycylic aromatic hydrocarbons (PAHs), while polar tar aerosols consist of a high number of oxidized aromatic substances (e.g., methoxy-phenols, benzenediol) with higher O : C ratio and carbon oxidation state. Fresh tar aerosols have light absorption characteristics similar to atmospheric BrC with higher absorption efficiency towards the UV wavelengths. The average retrieved refractive index (RI) are 1.661 + 0.020i and 1.635 + 0.003i for the nonpolar and polar tar aerosols, respectively, with absorption Ångström exponent (AAE) between 5.7 and 7.8 in the wavelength region 365–425 nm. The RI fits a volume mixing rule for internally mixed nonpolar/polar tar aerosols. The RI of the tar aerosols decreased with increasing wavelength under photochemical oxidation. Photolysis by UV light (254 nm), without strong oxidants in the system, slightly decreased the RI and increased the oxidation state of the tar balls. Oxidation under varying OH exposure levels and in the absence of NOx diminished the absorption (bleaching), and increased the O : C ratio. The photobleaching of tar ball aerosols via photochemically induced OH-oxidation is mainly attributed to decomposition of chromophoric aromatics, nitrogen-containing organics, and high-molecular weight components. Photolysis of nitrous oxide (N2O) was used to simulate NOx-dependent photochemical aging of tar balls in the OFR. Under high NOx conditions, photochemical aging lead to the formation of organic-nitrates, increased oxidation degree and increased absorption for the tar ball aerosols. These observations suggest that secondary organic nitrate formation compensates the bleaching by photolysis and OH radical photooxidation to eventually regain some absorption of aged tar balls aerosols. The atmospheric implication and climatic effects from tar balls upon various oxidation processes are briefly discussed.

Study of Coagulant Effect on Shallow-Bed (Traveling-Bridge) Contact Filtration for Effluent Reuse

1999 ◽  
Vol 40 (4-5) ◽  
pp. 91-98
Author(s):  
Haim Cikurel ◽  
Itay Sirak ◽  
Nelly Icekson Tal ◽  
Yaakov Zack ◽  
Avner Adin
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Dose Range ◽  
Cationic Polymers ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Effective Removal ◽  
High Charge Density ◽  
Secondary Effluents ◽  
Filter Bed

In this study, a shallow-bed traveling-bridge (SBTB) filter was used as a contact filter, to investigate the effect of coagulant addition to the filtration efficiency. The filter bed was 25 cm deep, containing 0.55 mm quartz sand. 10–15 m3/hr. secondary effluents were filtered at 3.5–5 m/hr. For different alum doses effective removal of particulates up to (70–80%), turbidity (65–70%) and phosphates up to (80–90%) was obtained. The headloss data indicated an increasing surface straining with the addition of alum which, by changing the (aluminum/TSS) ratio, increased the floc volume. For this reason an optimum alum dose range would be 10–15 mg/l. The efficiency of using high molecular weight, medium to high charge density cationic polymers as primary coagulants was also investigated. The medium cationic high molecular weight polymer used as a primary coagulant at a 0.5 mg/l dose was able to efficiently remove > 10 μm particulates but did not significantly improve turbidity. The same polymer used at a 3 mg/l dose improved the removal of the whole range of particles. By using a high cationic high molecular weight polymer as a secondary coagulant it was possible to decrease the alum dose necessary for an efficient filtration.

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