Flocculation studies based on water‐soluble polymers of grafted carboxymethyl cellulose and polyacrylamide (original) (raw)
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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, 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
A novel polymeric flocculant based on polyacrylamide grafted carboxymethylstarch
Carbohydrate Polymers, 2009
Novel functionalized polymeric flocculants based on polyacrylamide grafted carboxymethylstarch (CMSg-PAM) have been successfully synthesized via conventional method (using ceric ammonium nitrate as free radical initiator, in an inert atmosphere) as well as by using microwave irradiation ('microwave initiated' synthesis). Under optimal grafting conditions, 50% grafting has been observed in case of the microwave irradiation based method and 47% grafting has been observed in case of the conventional process. The synthesized graft copolymers have been characterized by elemental analysis, FTIR spectroscopy, intrinsic viscosity measurement, molecular weight determination, 13 C NMR spectroscopy and scanning electron micrograph (SEM); taking carboxymethylstarch (CMS) as reference. The effects of reaction parameters onto the percentage of grafting have been studied. Further, the applicability of these grafted polymers as flocculants for the treatment of municipal sewage wastewater has also been investigated.
Flocculative ability of uncharged and hydrolyzed graft and linear polyacrylamides
Journal of Molecular Liquids, 2017
Uncharged and anionic copolymers Dextran-graft-Polyacrylamide (D-g-PAA) and linear PAA of similar molecular weight were tested as flocculants in model kaolin polydisperse suspensions (C = 3 g/dl) having high content of particles less than 2 μm in size (more than 60%) which are difficult to settle down. The flocculation process was characterized by suspension sedimentation rate and degree of supernatant clarification. Dependence of flocculation on the degree of branched copolymers compactness as well as the degree of hydrolysis of the amide groups in the polymers was investigated. The main regularities of selection of suitable branched flocculants based on D-g-PAA and optimal their concentration for effective flocculation process was obtained. It was shown that D-g-PAA in ionic form with the lower grafting efficiency and long PAA grafts ensured the highest degree of supernatant clarification and the highest rate of the suspension sedimentation.
Bioresource Technology, 2011
The flocculation behavior of cationic, quaternary ammonium groups containing cellulosic biopolymers, CDACs, synthesized by cationizing dialdehyde cellulose in mild aqueous solution was studied in a kaolin suspension. In particular, the role of CDAC dosage and solution pH, NaCl concentration, and temperature were clarified. In addition, the initial apparent charge densities (CDs), particle sizes, f-potential, and stability of CDs were determined. CDACs possessed a high flocculation activity in neutral and acidic solutions, but a significant decrease was observed in alkaline solutions (pH >9). This was also seen as a decline in the apparent CD and particle size of the CDACs in alkaline conditions. The measurements also indicated that the apparent CD decreased to a constant level of 3 mmol/g in aqueous solutions. However, no notable decrease in flocculation performance was obtained after several days of storage. Moreover, the variation of NaCl concentration and temperature did not affect the flocculation activity.
Journal of Applied Polymer Science, 1998
The article deals with the synthesis of two polysaccharide-based graft copolymers of acrylamide, namely, starch-g-polyacrylamide (St-g-PAM) and amylopecting-polyacrylamide (Ap-g-PAM). Intrinsic viscosity of the graft copolymers was determined. A flocculation jar test was carried out with Ϫ200# ASTM particles for two coking and two noncoking coal samples from Indian coalfields. It is observed that both the grafted products are very effective flocculants in bringing down the turbidity of supernatant liquid of coking coal fines suspension. Though they are effective flocculants in the case of noncoking coal suspension as well, the supernatant turbidity remains somewhat high. Ap-g-PAM performed better than St-g-PAM, which is distinctly apparent in the case of noncoking coal suspension. This may be ascribed to the presence of longer grafted polyacrylamide chains in case of Ap-g-PAM.
2018
In the last few years, science and technology have made remarkable discoveries in the field of bio-renewable materials. In this context, polysaccharide based biopolymers present themselves as a high potential source of innovation. Due to its availability and biodegradability, Cellulose, the polymer belonging to the polysaccharide family, has a great interest today. Indeed, it is considered to be one of the most common organic polymers and an almost eternal source of raw material for the growing demand of eco-friendly materials. The objective of this work is to propose the elaboration of new water-soluble cellulose-acrylamide derivatives destined to the application as new bio-based flocculants for colloidal solution of Fe(OH)3. However, the new cellulose based floculants, cellulose acrylamide (Cac) and hydroxyethyl cellulose acrylamide (HECac), were elaborated in alkali medium. Since, the structural characterization showed that the reached degree of the substitution (DS) is close to ...
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).
Industrial & Engineering Chemistry Research, 2013
This manuscript illustrates the feasibility of polyacrylamide grafted xanthan gum/silica based nanocomposite toward its potential application as high performance flocculant for treatment of synthetic effluents and mine wastewater. The flocculation performance of the nanocomposite was systematically evaluated by floc size measurement as well as by traditional turbidity and settling velocity measurement. The flocculation kinetics is in good agreement with the aggregation of particle and particle collision model simultaneously. Furthermore, the effect of flocculant dosage on the synthetic effluent (kaolin and iron-ore suspensions) suggests that the bridging flocculation mechanism is predominating here. The graft copolymer-based nanocomposite also possesses a comprehensive color removal ability from mine wastewater.