Flocculative ability of uncharged and hydrolyzed graft and linear polyacrylamides (original) (raw)
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Ecological Chemistry and Engineering S-chemia I Inzynieria Ekologiczna S, 2011
Brush-like copolymers of Polyacrylamide grafted onto Dextran Sulphate backbone were tested as flocculation aids in polydisperse kaolin suspension. It was shown that flocculation efficiency of these copolymers is significantly dependent upon their internal structure. Both the kinetics of flock sedimentation and supernatant clarification of suspensions are the function of macromolecule conformation of copolymers in water solution. The most efficient flocculants are copolymers with high molecular mass but low value of Rz /Mw.
2008
Dextran-graft-polyacrylamide and Dextran Sulphategraft-polyacrylamide copolymers have been tested as flocculation aids in model kaolin suspens ions in comparison with linear Polyacrylamides of t he similar molecular weight. According to the sedimentation ra te nd the final sediment volume the graft copolyme rs are more effective flocculants than the linear polyacry lamides. According to the supernatant liquid clarit y the copolymers are proved to be rather similar to the linear homopolymer. The supernatant clarity is inversely r ated to the length of the grafts. Due to the most expanded macr omolecular conformation in solution the copolymer b ased on Dextran-Sulphate backbone is the most efficient for water clarification.
Flocculation properties of Dextran-graft-Polyacrylamide of various internal structure
Ecological Chemistry and Engineering. A, 2008
Two series of Dextran-graft-Polyacrylamide copolymers (D-g-PAA) with polysaccharide backbone having different molecular weights (Mw = 20 000 and Mw = 70 000) and with 5, 10, 15 or 20 PAA-grafts per one Dextran macromolecule were tested as flocculation aids in the model kaolin suspensions. These copolymers have shown high flocculation efficiency significantly dependent upon their internal structure. The flocculation ability of D-g-PAA samples with the same number of PAA-grafts inversely relates to the spacing of the grafts (ie the length of backbone between the grafts).
Desalination, 2011
A ferric chloride-polyacrylamide inorganic-organic hybrid polymer has been synthesized using a ferric chloride/ polyacrylamide ratio of 1:1 via free radical solution polymerization. A redox initiation system -(NH 4 ) 2 S 2 O 8 and NaHSO 3 was used to initiate the polymerization at 50°C in aqueous medium. The ferric chloride-polyacrylamide hybrid polymer was characterized using Fourier transform infrared (FT-IR) spectrometer to determine their functional groups in the hybrid polymer chain. The FeCl 3 -PAM hybrid polymer was tested for flocculating activities on kaolin suspension and Terasil Red R dye wastewater. Parameters such as solution pH and FeCl 3 -PAM hybrid polymer dosage have been studied. One-way ANOVA shows that pH has a significant impact (p b 0.05) in flocculating both kaolin suspension and Terasil Red R wastewater. The results show a minimum dosage of 2 mg/L is able to remove more than 99% of turbidity in kaolin suspension at pH 2. FeCl 3 -PAM hybrid polymer also shows its capability in flocculating Terasil Red R dye wastewater. It is able to reduce 89% of COD and 99% of colour at pH 5 using 500 mg/L of dosage.
Separation and Purification Technology, 2010
The flocculation of kaolin suspension in water using a novel calcium chloride-polyacrylamide hybrid polymer has been studied. A redox initiation system -(NH 4 ) 2 S 2 O 8 and NaHSO 3 was used to initiate free radical solution polymerization of one molar acrylamide solution at 50 • C. One mole of calcium chloride was blended with polymerized acrylamide solution to synthesis a novel inorganic-organic composite polymer (CaCl 2 -PAM hybrid polymer). The CaCl 2 -PAM hybrid polymer was characterized using Fourier transform infrared spectrometer (FT-IR) and transmission electron microscopy (TEM). TEM image showed that the CaCl 2 -PAM hybrid has a bulky and web-like nature. The CaCl 2 -PAM hybrid polymer was used in flocculating kaolin suspension. A factorial design was used in screening the factors for the flocculation of kaolin suspension to study the effect of two operating parameters (pH and dosage). The kaolin suspension flocculation was found to be pH and dosage dependent. Response surface methodology was done using central composite design and showed that the CaCl 2 -PAM hybrid polymer was able to reduce >98.0% of turbidity. The optimal operating condition was reported between pH 2 and 2.5 and dosage between 2 and 3 mg/L.
Development of graft copolymer flocculating agents based on hydroxypropyl guar gum and acrylamide
Journal of Applied Polymer Science, 2001
Graft copolymers of hydroxypropyl guar gum (HPG) with polyacrylamide (PAM) have been synthesized using a ceric ion-induced solution polymerization technique at 28°C. Six graft copolymers have been synthesized with variation in the number and length of grafted PAM chains. The graft copolymers were characterized by viscometry, infrared (IR) spectroscopy, and thermal analysis studies. Flocculation jar tests were carried out in 0.25 wt % kaolin, iron ore, and silica suspensions. Among the series of graft copolymers, the one with fewest but longest PAM chains shows the better performance. The flocculation characteristics of this best performing graft copolymer are compared with various commercially available flocculants in the three suspensions.
Journal of Applied Polymer Science, 2006
Graft copolymers of carboxymethylcellulose and polyacrylamide were synthesized by a ceric‐ion‐induced solution polymerization technique. By the variation of the monomer and catalyst concentrations, six grades of graft copolymers were synthesized. The synthesized graft copolymers were characterized with intrinsic viscosity measurements, IR spectroscopy, and X‐ray diffractometry. The flocculation characteristics of the graft copolymers were studied in kaolin (5 wt %), iron‐ore (10 wt %), and silica (10 wt %) suspensions. The flocculation characteristics of the best performing graft copolymer were then compared with those of various commercially available flocculants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1000–1007, 2006
Effect of polyacrylamide polymers on floc size and rheological behaviour of kaolinite suspensions
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2007
The influence of cationic and anionic polyacrylamides (PAM) on the floc size, compressive yield stress, and rheological behaviour of kaolinite suspensions has been investigated at pH 7. At optimum polymer concentrations, the kaolinite floc sizes were larger in the presence of anionic PAM than cationic PAM. However, increasing the cationic and anionic surface charge from 10 to 35% reduces the floc size and increasing the anionic and catatonic molecular weight increases the floc size. The results show that the magnitude of the compressive yield stress, yield stress, critical stress, elastic and viscous modulus are strongly dependent upon the floc structure; with greater values being observed for the cationic PAM than for the anionic PAM. The difference in the compression or shear sensitivity of the flocculated slurries may be attributed to floc structure-related adsorption. It is found that the compressive yield stress, yield stress and viscoelastic behaviour are important factors that should be considered when selecting the type of polyelectrolyte for use in a particular solid-liquid separation. This work has been very successful in establishing the link between greater particle attraction and higher compressive yield stress yield stress, critical stress, and elastic and viscous modulus.
Journal of Applied Polymer Science, 2013
The graft copolymerization of N,N-dimethylacrylamide (DMA) and acrylamide (AM) were carried out onto different polysaccharide backbones separately. The graft copolymers were synthesized by ceric ion induced redox polymerization technique. Three polysaccharides were used, namely hydroxyethyl starch (HES), hydroxyethyl cellulose (HEC) and Amylopectin (AP), for the grafting reactions. Among the three polysaccharides, HEC has linear structure, while HES and AP have a branch one. The graft copolymers were characterized by intrinsic viscosity measurements, FTIR spectroscopy, NMR (both 1 H and 13 C) spectroscopy, and thermal analysis. Flocculation performances of the graft copolymers were evaluated in 1 wt % kaolin and in 0.25 wt % iron ore suspensions. A detailed comparative study of the flocculation properties of the synthetic graft copolymers was also made. It showed that graft copolymers based on DMA were better flocculants than those based on AM. Among the synthetic graft copolymers, HES-g-Poly (DMA) performed best when compared with the other synthetic graft copolymers as well as to the commercial flocculants in the same suspensions. V
International Journal of Polymer Science
P(AM-DMC) (PAD) was synthesized by ultraviolet- (UV-) initiated copolymerization with methacryloxyethyl trimethyl ammonium chloride (DMC) and acrylamide (AM) as the monomers and initiator 2,2-azobis [2-(2-imidazolin-2-yl) propane] dihydrochloride (VA-044) as the photoinitiator. Parameters that affect the molecular weight were reviewed by using the single-factor approach. The results showed that the molecular weight (MW) of PAD could come to 7.88 × 106 Da with the optimum polymerization conditions as follows: monomer concentration of 30%, monomer mass ratio m(AM) : m(DMC) of 3 : 1, initiator concentration of 0.6‰, illumination time of 80 min, solution pH value of 4.5, and incident light intensity of 1000 μW cm−2. The PAD was represented by several instruments. The results of FTIR and 1H NMR showed that PAD was indeed polymerized by AM and DMC. The results of TGA showed that PAD was very stable at room temperature while the result of SEM revealed that PAD had a porous structure and ro...