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.

Simultaneous preparation of cellulose nanocrystals and micron-sized porous colloidal particles of cellulose by TEMPO-mediated oxidation

2015 ◽  
Vol 17 (2) ◽  
pp. 808-811 ◽  
Author(s):  
Jessie Peyre ◽  
Timo Pääkkönen ◽  
Mehedi Reza ◽  
Eero Kontturi
Keyword(s):  
Charge Density ◽  
Cellulose Nanocrystals ◽  
Colloidal Particles ◽  
Length Scales ◽  
Porous Particles ◽  
High Charge ◽  
High Charge Density ◽  
Mediated Oxidation

TEMPO-mediated oxidation of microgranular cellulose results in particles of three different length scales: cellulose nanocrystals as well as small (μm) and larger (tens of μm) porous particles with high charge density.

Conditioning of Biological Sludges with Cationic Poly-Electrolytes

1987 ◽  
Vol 19 (5-6) ◽  
pp. 859-868 ◽  
Author(s):  
L. Eriksson
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Colloidal Particles ◽  
Large Degree ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Capillary Suction ◽  
Dispersed Particles ◽  
High Charge Density

Factors determining polyelectrolyte choice and dosage in conditioning of activated sludge were investigated. It was found that due to differences in particle size distribution electrophoretic mobility did not correlate with optimal dosages. Instead the polyelectrolyte consumption to a large degree could be explained by a linear model containing the variables: sludge volume index, rest turbidity, floc break up factor obtained by CST-stirring test and CST (Capillary Suction Time) of unconditioned sludge. For the investigated sludges biopolymers and colloidal particles were the main consumers of polyelectrolyte which however also was needed to build the existing flocs to optimum properties. The model was statistically less significant in the cases of high stirring times and high sludge volume indexes. Sludges with high amounts of dispersed particles were best conditioned by a high molecular weight and moderately charged polymer while for well flocculated sludges with high sludge volume index a high charge density polymer was most suitable.

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.

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 Characterization of Soil Organic Matter Individual Fractions (Fulvic Acids, Humic Acids, and Humins) by Spectroscopic and Electrochemical Techniques in Agricultural Soils

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1067
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Romualda Bejger ◽  
Guillaume Debaene ◽  
Bożena Smreczak
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
Agricultural Soils ◽  
Fulvic Acids ◽  
Sorption Properties ◽  
Aliphatic Chains

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.

scholarly journals Insight to Microbial Fe(III) Reduction Mediated by Redox-Active Humic Acids with Varied Redox Potentials

2021 ◽  
Vol 18 (13) ◽  
pp. 6807
Author(s):  
Jingtao Duan ◽  
Zhiyuan Xu ◽  
Zhen Yang ◽  
Jie Jiang
Keyword(s):  
Molecular Weight ◽  
Electron Transfer ◽  
Humic Acids ◽  
Weight Fraction ◽  
Electrochemical Analysis ◽  
Microbial Reduction ◽  
Redox Potentials ◽  
Groundwater Environment ◽  
Redox Active ◽  
Different Molecular Weight

Redox-active humic acids (HA) are ubiquitous in terrestrial and aquatic systems and are involved in numerous electron transfer reactions affecting biogeochemical processes and fates of pollutants in soil environments. Redox-active contaminants are trapped in soil micropores (<2 nm) that have limited access to microbes and HA. Therefore, the contaminants whose molecular structure and properties are not damaged accumulate in the soil micropores and become potential pollution sources. Electron transfer capacities (ETC) of HA reflecting redox activities of low molecular weight fraction (LMWF, <2.5) HA can be detected by an electrochemical method, which is related to redox potentials (Eh) in soil and aquatic environments. Nevertheless, electron accepting capacities (EAC) and electron donating capacities (EDC) of these LMWF HA at different Eh are still unknown. EDC and EAC of different molecular weight HA at different Eh were analyzed using electrochemical methods. EAC of LMWF at −0.59 V was 12 times higher than that at −0.49 V, while EAC increased to 2.6 times when the Eh decreased from −0.59 V to −0.69 V. Afterward, LMWF can act as a shuttle to stimulate microbial Fe(III) reduction processes in microbial reduction experiments. Additionally, EAC by electrochemical analysis at a range of −0.49–−0.59 V was comparable to total calculated ETC of different molecular weight fractions of HA by microbial reduction. Therefore, it is indicated that redox-active functional groups that can be reduced at Eh range of −0.49–−0.59 are available to microbial reduction. This finding contributes to a novel perspective in the protection and remediation of the groundwater environment in the biogeochemistry process.

A tensammetric study of the adsorption of cationic polymers and copolymers

1991 ◽  
Vol 69 (10) ◽  
pp. 1516-1519
Author(s):  
Truis Smith-Palmer ◽  
Cheryl Roberts
Keyword(s):  
Molecular Weight ◽  
Charge Density ◽  
Key Words ◽  
Potential Versus ◽  
Cationic Polymers ◽  
Capacitive Current ◽  
Cationic Polyacrylamide

The tensammograms of several sets of cationic polyacrylamide copolymers are discussed and compared. Tensammograms are not affected by molecular weight, but plots of capacitive current at a chosen potential versus charge density give regular curves. Key words: tensammetry, cationic, polyacrylamide, charge density.

THE EXTRACTION OF ORGANIC MATTER FROM SELECTED SOILS AND PARTICLE SIZE FRACTIONS WITH 0.5 M NaOH AND 0.1 M Na4P2O7 SOLUTIONS

1989 ◽  
Vol 69 (2) ◽  
pp. 253-262 ◽  
Author(s):  
M. SCHNITZER ◽  
P. SCHUPPLI
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acids ◽  
Nmr Spectra ◽  
Attractive Alternative ◽  
Particle Size Fractions ◽  
Molecular Weights ◽  
Naoh Solution ◽  
C Nmr ◽  
Medium Silt

Organic matter (OM) in the Bainsville and Melfort soils, and in coarse clay and medium silt fractions separated from these soils, was extracted under N2 with 0.5 M NaOH and unadjusted 0.1 M Na4P2O7 solutions. pH ranges of the soils and fractions in contact for 24 h with 0.5 M NaOH and 0.1 M Na4P2O7 solutions extended from 12.2 to 12.6 and 9.0 to 9.4, respectively. Slightly greater proportions of the soil-carbon were extracted by 0.5 M NaOH than by 0.1 M Na4P2O7 solution. The differences, however, did not appear to be significant and may vary from soil to soil. The efficiency of extraction and the characteristics of the extracted materials were assessed on humic acids (HAs), which were isolated from the extracts. From the Bainsville soil and fractions, 0.1 M Na4P2O7 solution extracted more high-molecular weight and more deeply colored HAs than did 0.5 M NaOH solution. But HAs extracted from the Melfort soil and fractions had similar molecular weights and colours. 13C NMR spectra showed that HAs extracted by 0.1 M Na4P2O7 solution tended to be more aromatic than HAs extracted by 0.5 M NaOH solution. Well defined solid-state 13C NMR spectra of HAs, containing up to 69.0% ash, could be recorded. Unadjusted 0.1 M Na4P2O7 solution under N2 was found to be an attractive alternative to 0.5 M NaOH solution as an extractant for soil OM. Key words: Humic acids, E4:E6 ratios, IR spectra, 13C NMR spectra, aromaticity

Effect of extractant and molecular size on the optical and chemical properties of soil humic acids

Soil Research ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 229 ◽  
Author(s):  
JHA Butler ◽  
JN Ladd
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Humic Acids ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Molecular Size ◽  
Carboxyl Content ◽  
Peptide Bonds ◽  
Molecular Weights ◽  
Amino Acid Contents

Humic acids extracted from soil with sodium pyrophosphate have greater proportions of lower molecular weight material, less acid-hydrolysable amino acid nitrogen contents, but greater carboxyl contents and extinction values (260 and 450 nm) than humic acids extracted subsequently from the same sample with alkali. Humic acids extracted with alkali from fresh soil samples have intermediate values. Extinction values at 260 nm are directly correlated with carboxyl contents for a given soil. Different crop histories have no significant effect on the measured properties of the extracted humic acids. An alkali-extracted humic acid has been fractionated by gel filtration into seven fractions of different nominal molecular weight ranges. As the molecular weights of the fractions increase, both aliphatic C-H (based on infrared absorption at 2900 cm-1) and acid-hydrolysable amino acid contents increase, whereas extinction values at 260 nm and carboxyl contents decrease. The infrared spectra of the high molecular weight fractions have peaks at 1650 and 1510 cm-1 which correlate with acid-hydrolysable amino acid contents and which correspond to amide I and II bands of peptide bonds. Alkaline hydrolysis to split peptide bonds eliminates both these peaks. The spectra also have peaks at 1720 and 1210 cm-1 which correlate with the carboxyl content.

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