Title of Invention

A STARCH BASED CATIONIC AMYLOPECTIN

Abstract

A selective starch based cationic amylopectin adapted for use as a flocculant comprising of the general formula 1 hereunder: Cationic Amylopectin wherein the amylopectin comprise amylopectin from maize of Mol. Wt. ranging from106-107 The grafted polysaccharide of Formula-I above involves selective polysaccharide which is highly branched and high molecular weight amylopectin (of 106-107) from maize. Importantly also, the amylopectin source from maize is much cheaper than the amylopectin source from other starch which again add to the selective benefits of the cationized amylopectin. The cationic polymeric flocculant in particular cationic amylopectin is found to be versatile, useful and efficient as a flocculating agent and can be obtained by a simple and cost-effective process. It would be effective even at lower dosages and thus would be cost-effective also in use. It is found to have desired shear stability, controlled biodegradability and considerable shelf life.

Full Text

Field of the Invention The present invention relates to polymeric flocculants and to novel polyacrylamide (PAM) grafted polysaccharides; in particular, selective amylopectin based grafted polysaccharide and its process of manufacture for use as a flocculant. The invention also relates to the process for flocculation involving the novel polyacrylamide (PAM) grafted copolymer. Importantly, the selective cationic amylopectin of the invention is simple and cost-effective to obtain and directed to achieve high flocculation. Advantageously, the cationic amylopectin of the invention apart from sen/ing such useful selective purpose as a good flocculating agent being cost-effective would favour wide scale use and application of the same as an effective flocculant. This application is divided out of patent application 0483/KOL/2003 dated 17/09/2003 vide section 16 of the Indian Patents Act, 1970. Background Art Organic and inorganic flocculants are well known especially in the treatment of water and industrial effluents. Polymeric flocculants both synthetic as well as natural because of their inertness to pH changes, low dosage and easy handling are found to be popular in industrial effluent treatment. The synthetic polymer used as flocculant are mostly linear water-soluble polymers such as polyacrylamide, polyacrylic acid, Poly (diallyl dimethyl ammonium chloride) (DADMAC) and ploy (styrene sulphonic acid) etc. Among natural polymers guar gum, starch and alginic acid are very often used as flocculants or retention aids. Importantly, synthetic flocculants are usually available in all the three forms i.e. cationic, anionic and nonionic. Synthetic polymers can be tailor made by controlling molecular wt., distribution, the system of polymers and the nature and percentage of ionic groups. Attempts have been made to combine the best properties of synthetic and natural polymers by grafting synthetic polymers onto the backbone of natural polymers. This has lead to possible reduction in biodegradability as well as avoiding problems of shear degradability of polymers. Among the grafted guar gum, xanthan gum, carboxymethyl cellulose, sodium alginate and starch, it has been found that grafted starch is most preferable as a flocculant Starch consists of linear amylose (molecular weight 10,000-60,000) and branched amylopectin (molecular weight = 50.000-106). Hence amylose and amylopectin are known to have grafted with polyacrylamide Among all polysaccharides grafted amylopectin is known to have the best flocculation efficiency. In view of the above advantageous use/applications of graft copolymers, various forms of grafted polysaccharides have been developed and used over the years. The publication "Flocculation of Cationic Amylopectin Starch and Collodial Silicic Acid. The Effects of Various Kinds of Salt" - by Anders Larsson et al. reveals the study results of kinetics of the flocculation of nanosized silica particles (5 nm) with cationic amylopectin. The above publication proposes the use of amylopectin derived from specific potato strain only producing amylopectin. The synthesis of cationic amylopectin involving said potato specific strain for the kinetics of flocculation was performed by dissolving the native amylopectin in water in a nitrogen atmosphere at about 95°C for about 30 min. which was later cooled to 55°C. Thereafter, a mixture of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (QUAB) and 120 ml of 1M sodium hydroxide was added to the solution. The amylopectin was cationized during the night. The pH was then lowered to below 7 with HCI to stop the cationization process. The solution was thereafter cooled to room temperature and the amylopectin was precipitated in isopropanol. The cationized amylopectin was then dissolved again in water at about 90°C for 30 min. Finally, the amylopectin solution was cooled to room temperature and the amylopectin was precipitated by adding Isopropanol in the presence of a salt. Thereafter, the precipitated amylopectin was dried at about 55°C to remove the isopropanol. The obtained cationic amylopectin from the potato starch was used to study its flocculation characteristics of nanosized silica particles (5m). The key findings in said publication were directed to kinetic mechanism observed during flocculation which proposed an initial binding flocculation when the large amylopectin molecules gather a number of the small silica particles forming a polyelectrolyte complex. This was followed by a collapse of the formal floes. The effect of mix and divalent ions on the flocculation was also studied. Importantly, it was concluded in said publication that the method of cationization and dissolution of kind of potato starch used did not affect the basic behavior of the flocculation process, it would be apparent from the above that while use of such cationic amylopectin of potato starch is proposed, the manner of producing the cationic amylopectin followed is found to be complex in that the selected amylopectin from potato essentially required a nitrogen atmosphere to form solution and the precipitation of the cationic amylopectin was to be carried out in the presence of salt. Also, the specific use of the cationic amylopectin from potato starch is an expensive source for the amylopectin. In view of the aforesaid, further developments on simple and cost effective and industrially viable starch based cationic amylopectin as an effective flocculant is a continuing need in the art. Objects of the Invention It is thus the basic object of the present invention to provide for novel cationic polymeric flocculant in particular cationic amylopectin useful as a flocculating agent which would be versatile, useful and efficient as a flocculating agent and can be obtained by a simple and cost-effective process. Another object of the present invention is to provide for a cationic polymeric flocculant in particular cationic amylopectin useful as a flocculating agent which would be effective even at lower dosages and thus would be cost-effective also in use. Yet another object is to provide cationic polymeric flocculant which on one hand would achieve high flocculation efficiency and on the other hand have desired shear stability, controlled biodegradability and considerable shelf life. Another object of the present invention is to provide for a simple and cost effective synthesis of selective cationic amylopectin from selective starch source which would make it simple and cost effective to obtain and thus more industrially feasible than the potato starch based amylopectin presently available. Yet another object of the present invention is to provide for synthesized cationic amylopectin which would have improved performance than the most other conventional cationic starch and cationic amylose presently used as flocculent. Another object of the present invention is directed to a high efficiency method of flocculation involving a selective cationic amyiopectin. Yet further object is directed to provide for novel flocculating agents/composition involving a selective synthesized cationic amyiopectin having high flocculation efficiency as well as shear stability and considerable shelf life. Summary of the Invention Thus according to the basic aspect of the present invention, there is provided a starch based cationic amyiopectin adapted for use as a floccuiant comprising of the general formula 1 hereunder: Cationic Amyiopectin wherein the amyiopectin comprise amyiopectin from maize of Mol. Wt. ranging from 106-107 It is important to note that in the grafted polysaccharide of Formula-I above the selective polysaccharide which is highly branched and high molecular wt. Amyiopectin is obtained from maize. The molecular weight range of potato amyiopectin used in the prior art varies from 104-106 while the selective maize amylopectin used in the above process has a molecular wt. of 106-107 It is found that with increase in molecular wt. the flocculation efficiency also increases and the cationic amylopectin of the present invention thus serves as a selective high efficiency flocculant. Importantly also, the amylopectin source from maize is much cheaper than the amylopectin source from potato starch which again add to the selective benefits in the cationized amylopectin and its process for manufacture. Importantly, in accordance with a further aspect, it is found that the loading of the cationic moiety i.e. N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride onto the amylopectin backbone is important in controlling the flocculation characteristics. In accordance with a preferred aspect of the present invention, there is provided a starch based cationic amylopectin adapted for use as a flocculant comprising of the general formula 1 hereunder: Cationic Amylopectin wherein the amylopectin comprise amylopectin from maize of Mol. Wt. ranging from 106-107 and the cone, of amylopectin and monomer is in the range of 0.0079 to 0.0132 preferably 0.0106 moles of CHPTAC : 0.0123 to 0.0246 preferably 0.0185 moles of amylopectin calculated based on the anhydroglucose units (AGU) present (1 mole ofAGU = 162gm.) By way of selective loading, the above cationic amylopectin was found to achieve much better performance than other cationic polysaccharides such as cationic starch, cationic amylose and various commercial flocculants. The above selective grafted polysaccharide of the invention is an effective cationic amylopectin wherein on the selective amylopectin for maize the cationic moiety N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride has been chemically linked. Such a selective cationic amylopectin is found highly suitable as a flocculant for highly negatively charged particles. Importantly also, in view of the ready and cost-effective source of amylopectin from maize as compared to the other known source of amylopectin from potato starch, the cationic amylopectin of the invention is found to be superior not only in terms of the performance i.e. the efficiency as a flocculant but also in terms of the cost benefit which such cationic amylopectin would achieve vis-a-vis conventional cationic flocculants including the amylopectin from potato starch. According to another aspect of the present invention there is provided a process for manufacture of the cationic amylopectin of Formula 1 comprising: i) providing a solution of amylopectin from a selective amylopectin source from maize; ii) adding a mixture of N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride and sodium hydroxide to said selective solution of amylopectin; and allowing the reaction to continue for 15-24 hrs. at about 40-50°C; iii) adding dilute HCI to the reaction mixture and precipitating therefrom the cationic amylopectin. In the above process of the invention the selective source of amylopectin is maize which favours dissolution of the amylopectin in water without the need for any special nitrogen atmosphere as proposed by the known art. In accordance with a preferred aspect the above process comprises selective loading wherein the cone, of amylopectin and monomer is in the range of 0.0079 to 0.0132 preferably 0.0106 moles of CHPTAC: 0.0123 to 0.0246 preferably 0.0185 moles of amylopectin calculated based on the anhydroglucose units (AGU) present. (1 mole of AGU = 162 gm.). In accordance with another preferred aspect of the present invention there is provided a process for producing cationic amylopectin of Formula-I comprise: a) dissolving selective source of amylopectin from maize in water at a temperature range of 70°C to 90°C preferably 80°C for a period of 0.5 hour to 1.5 hour preferably one hour; b) cooling the solution to a temperature of 45°C to 55°C preferably 50°C; c) adding the mix of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride and sodium hydroxide to the amylopectin solution such that the cone, of amylopectin and monomer is in the range of 0.0079 to 0.0132 preferably 0.0106 moles of CHPTAC : 0.0123 to 0.0246 preferably 0.0185 moles of amylopectin calculated based on the anhydroglucose units (AGU) present. (1 mole of AGU = 162 gm.). d) continuing the reaction for a period of 15 to 24 hours at a temperature range of 40 to 50°C; e) adding dilute HCI to the reaction mixture; f) cooling the solution to room temperature and precipitating in isopropanol; g) finally filtering the product and drying in a vacuum oven for 40 to 50°C preferably 45°C. Importantly, in the above selective synthesis of amylopectin, the dissolution of amylopectin in water could be attained without the involvement of nitrogen atmosphere. Also, for precipitating the cationic amylopectin by addition of isopropanol under the known art it was essential to use some amount of salt but under the present process, the cationic amylopectin can be precipitated in isopropanol without the need for addition of salt. Advantageously therefore following the above selective process of the invention does not involve the requirement of any nitrogen atmosphere for dissolving amylopectin in water. Also, the desired cationic amylopectin can be precipated by simple addition of ispropanol without the need for any salt for such precipitation. In accordance with yet another aspect of the present invention there is provided a method of flocculation comprising the step of using a starch based cationic amylopectin adapted for use as a flocculant comprising of the general formula 1 hereunder: Cationic Amylopectin wherein the amylopectin comprise amylopectin from maize of Mol. Wt. ranging from 106-107 In accordance with yet further aspect of the invention there is provided a flocculation composition having along with conventional ingredients of flocculation formulation a starch based cationic amylopectin adapted for use as a floccullant comprising of the general formula 1 hereunder: Cationic Amylopectin wherein the amylopectin comprise amylopectin from maize of Mol. Wt. ranging from 106-107 Detailed description of the Invention There is a continuing crisis of portable water and this has necessitated the treatment of municipal waste water with industrial effluents under water recycling paradigm. Usually, for such treatment, the contaminants are flocculated by organic and inorganic chemicals for liquid/solid separation. Polymeric flocculants are more versatile and efficient and could be used at lower dosages. Moreover, polymeric flocculant provide desired flexibility in producing anionic, nonionic and cationic polymers which could be selectively used depending upon the negativity of the contaminant particles and the pH of their colloidal suspension. By way of the present invention, as disclosed above, a new class of polymeric flocculant has been provided based on hydrolyzed and unhydrolyzed polyacrylamide (PAM) grafted polysaccharides. The flocculants which are selectively grafted cationic polysaccharide are found to have exceptionally high flocculation characteristics, shear stability and controlled biodegradation besides being useful in very low dosage (in ppm or sub ppm level). Importantly, the selective grafted copolymer of the invention makes selective advantages use of dangling PAM branches grafted on rigid polysaccharide backbone which have easy approachability to contaminants of the industrial effluents. Advantageously, it has been found that on further hydrolysis of grafted polysaccharides, the efficiency of the flocculants further increased due to extension of the polymer molecule. The selective polysaccharides involve highly branched and high molecular weight amylopectin based grafted polysaccharides which are adapted for selective high efficiency flocculation. These hydrolyzed and unhydrolyzed grafted polysaccharides are found to be very efficient flocculant in the industrial effluent of relatively low negativity. The cationized amylopectin of the invention selectively and advantageously provide for highly negatively charged particle effluent/suspensions. Importantly, it is found that the selective use of amylopectin for maize provided for obtaining of its solution without the need for nitrogen atmosphere. This simplifies the process of manufacture of cationic amylopectin. Also, following the above process of the invention, it was possible to avoid the need for salt during precipitation of the cationic amylopectin in isopropanol. The manner of manufacture of the cationic amylopectin of the invention is illustrated in greater detail hereunder in Scheme-1. The details of the invention, its objects and advantages are explained hereunder in greater detail by way of non-limiting exemplary illustrations of the manner of manufacture of the cationic amylopectin in accordance with the present invention as discussed in the following examples: Examples Under Examples 1 to 6, the synthesis of the cationic amylopectin with the selective source of amylopectin being maize amylopectin was carried out using varied cones, of the amylopectin (AGU) and N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride, sodium hydroxide and duration of reaction as detailed in TABLE I hereunder: The manner of synthesis followed in Examples 1 to 6 was as detailed hereunder: Amylopectin was dissolved in water at 80°C for one hour. No nitrogen atmosphere was required for the dissolving of the amylopectin. The solution was next cooled to 50°C and a mixture of N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride and sodium hydroxide was added to the amylopectin solution. The reaction was then continued for 15-24 hrs (depending on various grades) at 40-50°C. Then dilute HCI was added to the reaction mixture. The solution was then cooled at room temperature and the product was precipitated in isopropanol. No salt was required for such precipitation. Finally, the product was filtered and dried in a vacuum oven at about 45°C. Following the above process, six different grades of the cationic polymer (Cat AP1 to Cat AP 6) were obtained. The above six grades (CAT AP1 to CAT AP6) cationic polymers under Examples 1 to 6 were subjected to flocculation test as detailed hereunder: Fiocculation: Flocculation tests of various suspensions were carried out by a standard flocculation jar apparatus. The flocculation procedure was followed in the line of Bratby with minor modifications. The apparatus consisted of 6 stirrer blades connected to a variable speed motor through a gear system. The turbidity measurement was carried out with the Digital Nephelo Turbidity Meter, procured from Systronics (Ahmedabad, India); 0.25 wt% suspension of silica (prepared by mixing 1 gm in 400cc of distilled water) was used for flocculation study. The suspensions were taken in each of four 1-L beakers and the flocculants were added in solution form. The following procedure was uniformly applied to the suspension. Immediately after the addition of flocculants, the suspension was stirred at a constant speed of 75 rpm for 2 min, followed by stirring at 25 rpm for 5 min. The floes were then allowed to settle down for 10 min. At the end of the settling period, the turbidity of the supernatant liquid was measured. The doses of flocculants were varied from 0.025 to 1.0 ppm, calculated with respect to the total weight of the solution. The flocculation performance of the various grades (Cat AP1 To CAT AP6) of the cationized amylopectin was carried out in 0.25 wt% silica suspension. The results are noted and illustrated in accompanying Fig. 1. The turbidity of supernatant liquid after flocculation was plotted against polymeric concentration. As would be clearly apparent from the flocculation test result illustrated in accompanying figure 1, out of all the variants of the cationic polymer, it was the Cat AP3 which achieved the best and highest flocculation benefits. Example 7 Under this example, the selective CAT AP3 obtained in accordance with the present invention and its flocculation characteristics was next compared with six commercially available flocculants as detailed under Table II hereunder: To ascertain the flocculation characteristics of the cationic amylopectin3 (Cat AP3) of the invention vis-a-vis the above conventional flocculation of Table-ll, the same flocculation method detailed above was followed. For the purpose, 0.25wt% silica suspension was used. The turbidity of supernatant liquid after flocculation was plotted against polymer concentration. The results are represented in accompanying figure 2. As would be apparent from figure 2 that the cationic polymer CAT AP3 of the invention obtained under Example 3 was found to be the best out of the other conventional flocculants tried. Example 8 Under this example a comparative test of the cationic polymer of the invention CAT AP3 as a flocculant vis-a-vis the conventional cationic amylose (CAT AM) and cationic starch (CAT ST) was carried out under the same test conditions detailed above and the results are represented in accompanying figure 3. As would be apparent from the results represented in Figure 3, the cationic amylopectin (CAT AP) in accordance with the present invention was found to have superior and surprisingly higher flocculant activity vis-a-vis the conventional cationic amylose and cationic starch known for use also as flocculant. Example 9 Under this example to favour comparative study of the cationic amylopectin from maize amylopectin following the simple process of invention (according to Example 3 above) and the process of the known art of obtaining cationic amylopectin involving the use of nitrogen atmosphere to dissolve the amylopectin and using salt to precipitate the amylopectin maize based amylopectin was obtained following the conventional process as hereunder: Amylopectin was dissolved in water at 95°C for 30 min. in a nitrogen atmosphere and thereafter the solution was cooled at about 55°C. Subsequently, a mixture of 3-chloro-2-hydroxypropyl trimethyl ammonium chloride and sodium hydroxide was added to the amylopectin solution. The reaction was then continued for 15 hrs. Thereafter, dilute HCL was added to the reaction mixture. The solution was thereafter cooled to room temperature and the product was precipitated in Isopropanol using salt. At the end, the precipitate was washed with a mixture of 3:1 isopropanol: water five times to remove salt. Finally the product was dried at 55C. The maize based cationic amylopectin thus obtained following the known process and that obtained following the process of the invention (Cat AP 3) was subjected to flocculation test. The results were noted and are represented in accompanying Figure 4. As would be apparent from Figure 4, the cationic amylopectin in accordance with the invention achieved superior flocculation characteristics. It is thus possible by way of the above invention to provide for a selective synthesized cationic amylopectin having high flocculation efficiency and at the same time shear stability and considerable shelf life. The invention also provides for selective synthesis of cationic amylopectin having very high flocculation efficiency amongst various presently available cationic amylopectin as well as known flocculant such as cationic starch and cationic amylose. Importantly, the selective use of maize as the amylopectin source in the synthesized cationic amylopectin would favour for obtaining such cationic amylopectin effective as a flocculant at cost effective rate and thereby provide for a much wider and varied application of the cationic amylopectins as a flocculant. WE CLAIM 1. A starch based cationic amylopectin adapted for use as a flocculant comprising of the general formula 1 hereunder: Cationic Amylopectin wherein the amylopectin comprises amylopectin from maize; and the concentration of amylopectin and monomer is in the range of 0.0079 to 0.0132 moles of CHPTAC: 0.0123 to 0.0246 moles of amylopectin calculated based on the anhydroglucose units (AGU) present. 2. A starch based cationic amylopectin as claimed in claim 1 wherein the maize amylopectin has Mol. Wt. ranging froml06-107 3. A starch based cationic amylopectin as claimed in anyone of claims 1 to 2 comprising dangling PAM branches grafted on rigid polysaccharide backbone. 4. A starch based cationic amylopectin as claimed in any preceding claim, wherein the concentration of amylopectin and monomer is 0.0106 moles of CHPTAC: 0.0185 moles of amylopectin calculated based on the anhydroglucose units (AGU) present. 5. A starch based cationic amylopectin adapted for use as a floccullant substantially as herein described and illustrated with reference to the accompanying examples and figures. A selective starch based cationic amylopectin adapted for use as a flocculant comprising of the general formula 1 hereunder: Cationic Amylopectin wherein the amylopectin comprise amylopectin from maize of Mol. Wt. ranging from106-107 The grafted polysaccharide of Formula-I above involves selective polysaccharide which is highly branched and high molecular weight amylopectin (of 106-107) from maize. Importantly also, the amylopectin source from maize is much cheaper than the amylopectin source from other starch which again add to the selective benefits of the cationized amylopectin. The cationic polymeric flocculant in particular cationic amylopectin is found to be versatile, useful and efficient as a flocculating agent and can be obtained by a simple and cost-effective process. It would be effective even at lower dosages and thus would be cost-effective also in use. It is found to have desired shear stability, controlled biodegradability and considerable shelf life.

Documents:

424-kol-2004-abstract.pdf

424-kol-2004-claims.pdf

424-KOL-2004-CORRESPONDENCE.pdf

424-kol-2004-description (complete).pdf

424-kol-2004-drawings.pdf

424-kol-2004-examination report.pdf

424-kol-2004-form 1.pdf

424-kol-2004-form 18.pdf

424-kol-2004-form 2.pdf

424-kol-2004-form 3.pdf

424-KOL-2004-FORM-27.pdf

424-kol-2004-granted-abstract.pdf

424-kol-2004-granted-claims.pdf

424-kol-2004-granted-correspondence.pdf

424-kol-2004-granted-description (complete).pdf

424-kol-2004-granted-drawings.pdf

424-kol-2004-granted-examination report.pdf

424-kol-2004-granted-form 1.pdf

424-kol-2004-granted-form 18.pdf

424-kol-2004-granted-form 2.pdf

424-kol-2004-granted-form 3.pdf

424-kol-2004-granted-others.pdf

424-kol-2004-granted-pa.pdf

424-kol-2004-granted-reply to examination report.pdf

424-kol-2004-granted-specification.pdf

424-kol-2004-pa.pdf

424-kol-2004-reply to examination report.pdf

424-kol-2004-specification.pdf