ANIONIC POLYACRYLAMIDE
ANIONIC POLYACRYLAMIDE
Chemical name : . . . . . 2-propenoic acid, sodium salt polymer with 2-propenamide
Other names : . . . . . . Copolymer of acrylamide and acrylic acid, sodium salt
Acrylamide, sodium acrylate copolymer
CAS number : . . . . . . . 25987-30-8
EC / List no.: 607-842-3
CAS no.: 25987-30-8
Anionic flocculants are co-polymers of acrylamide with increasing proportions of acrylate groups, which give the polymers negative charges, and thus anionic active character, in aqueous solution.
Our anionic polyacrylamide is available in solid powder
What is Anionic Polyacrylamide?
• One of the most common polymer flocculants on the market
• Common uses of PAM as a flocculant:
reduction of sediment and nutrient loads to natural lakes and ponds
wastewater and drinking water treatment
clarification of effluents in industries like pulp & paper, aquaculture
• Also popular for erosion prevention in irrigation furrows and on construction sites.
• Promising performance and low toxicity findings in studies completed to date
Anionic Polyacrylamide is widely used in Oil & Gas, water treatment, textile, printing and dyeing, papermaking, mineral processing, coal washing, medicine, sugar, breeding, building materials, agriculture and other industries. It is known as the most widely used additive.
Anionic polyacrylamide is the generic name for a group of very high molecular weight macromolecules produced by the free-radical polymerization of acrylamide and an anionically charged comonomer, mainly the sodium salt of acrylic acid, sodium acrylate.
The combination of molecular weight and ionic charge results in extremely viscous aqueous solutions, one of the main properties of these polymers.
Both the charge density (ionicity), and the molecular weight can be varied.
By varying the acrylamide/anionic monomer ratio, a charge density from 0 to 100% along the polymer chain can be obtained.
The molecular weight is determined by the type and concentration of the reaction initiator and the reaction parameters.
Anionic polyacrylamide has no systemic toxicity to aquatic organisms or micro-organisms.
The polymer is much too large to be absorbed into tissues and cells.
The functional anionic groups do not interfere with the functioning of fish gills or daphnia respirators.
Any adverse effects observed in laboratory tests are always seen at concentrations of over 100 mg/L and are probably due to the resulting viscosity of the test medium.
The preparation of the test solutions at such concentrations requires high-energy stirring for long periods of time, sometimes several hours.
Therefore, it it can be concluded that these harmful concentrations will not exist in the natural environment
Anionic polyacrylamide has no potential to bioaccumulate, being completely soluble in water (solubility is only limited by viscosity) and insoluble in octanol.
Additionally, being a flocculent, it adsorbs onto suspended matter and, in this way, is removed from the water phase
Anionic polyacrylamide (APAM) is a kind of polyacrylamide (PAM) and shows electronegative which contains functional groups of sulfonic acid, phosphoric acid or carboxylic acid .
Due to more charge, the molecular chain of polymer can be more stretching in the water which will increase the capacity of adsorption and bridge for suspended particles removal.
The mainly interaction between APAM and suspended particles is static electricity, hydrogen bonding or covalent bond .
Anionic polyacrylamide with high molecular weight and good solubility property can be an important kind of flocculants.
And it has been widely used in water treatment because of good flocculation performance .
Generally, molecular weight of polysaccharide polymer is determined by intrinsic viscosity.
Accordingly, how to improve the intrinsic viscosity and solubility property of APAM is the most critical point in the polymerization.
Based on comprehensive literature survey to the preparation technology and application progress of APAM, it can be found that a detailed analysis and review of past academic research progress could be valuable with the rapid development of synthesis technology.
Homopolymerization posthydrolysis process, homopolymerization cohydrolysis process, copolymerization approach, inverse emulsion polymerization, precipitation polymerization and radiation polymerization are the main six kinds of synthesis technologies of APAM.
REVIEW Synthesis and Application of Anionic Polyacrylamide in Water Treatment
This review summarizes the synthesis methods for anionic polyacrylamide.
The paper lists six different kinds of anionic polyacrylamide synthesis technologies, including homopolymerization posthydrolysis process, homopolymerization cohydrolysis process, copolymerization approach, inverse emulsion polymerization, precipitation polymerization and radiation polymerization.
What’s more, the authors discussed the application status of anionic polyacrylamide in water treatment.
Based on these reviews, future research perspectives relating to its synthesis and application were proposed.
Key Words: Anionic polyacrylamide, Synthesis methods, Water treatment, Flocculants.
Fundamental aspects of these methods will be introduced and summarized.
The developments in applications will also be reviewed and discussed.
Finally, the main conclusions and future perspectives are presented.
Synthesis technology progress of APAM: The earliest in 1893, Moureu prepared polyacrylamide by using acryloyl chloride and ammonia in the low temperature.
And in 1954, America takes the lead in realizing the industrialization production of polyacrylamide.
However, in the 1960s,APAM was firstly developed through alkaline hydrolysis process in the world.
Up to now, synthesis technology of APAM has experienced a lot of improvements, the basic reaction of polymerization usually expressed as Fig. 1.
According to the APAM synthesis development history of these years, successively appeared the following six different synthesis technologies: Homopolymerization posthydrolysis process, homopolymerization cohydrolysis process, copolymerization approach, inverse emulsion polymerization, precipitation polymerization and radiation polymerization.
ANIONIC POLYACRYLAMIDE
Composition: Negatively charged copolymers of acrylamide are widely used as retention aids and dry-strength resins.
However, different molecular mass ranges are used for these two roles.
Anionic acrylamide copolymer retention aids typically have molecular masses in the range of 5 to 20 million grams per mole.
The strength agents typically have molecular masses in the hundreds of thousands. Another difference is in the form delivered to the mill.
Though anionic retention aids can be delivered as solid beads or in solution, it is more popular to get them as water-in-oil emulsions.
Before such emulsion products can be used they have to be “inverted” with a dilution of about 100-to-1 with a lot of agitation.
Further time (at least half an hour) is needed for the individual molecules to uncoil themselves and achieve their full potential as retention aids.
The monomers used in their preparation are acrylamide and acrylic acid.
The acrylic acid is usually present in its corresponding sodium salt form in the final formulation of retention aid or strength aid.
The strength agents are usually shipped as solutions having solids levels in the range of 10 to 50%. A wide range of charge density is available in each case.
Function: Retention aids (molecular mass 5-20 million grams per mole); dry-strength agents (mass in the 100,000’s g/mole). Some dispersants (lower mass, usually) have similar compositions.
Strategies for Use: First let’s consider the anionic acrylamide retention aids.
These are often used for alkaline papermaking, though they also can be used under acidic conditions.
The most basic rule is that the furnish must have a suitable “cationic source” to serve as anchoring points for the anionic retention aid.
Such materials as polydimethlammonium-epichlorohydrin (polyamine), polydiallyldimethylammonium chloride (poly-DADMAC), and cationic wet-strength resins are especially effective in this role as “promoters” of the retention aid.
Alum also can be used as a promoter, especially if the pH is below 6 or if the alum is added at a point where it is in contact with the furnish for a few minutes or less before the retention aid addition.
The most popular addition point for a retention aid is right after the pressure screen(s), since this gives the highest retention efficiency.
The papermaker has an incentive to use as little retention aid as practical – only enough to keep the paper machine from getting too dirty, to avoid basis weight fluctuations, and to avoid runnability problems.
Higher levels are likely to floc the fibers enough to hurt the uniform appearance of the paper, i.e. its “formation.”
Another alternative is to add the retention aid before the screen(s), possibly achieving a better balance between formation uniformity and retention.
Dry-strength resin performance tends to be highly dependent on the colloidal charge state of the system.
Whereas anionic retention aids merely need cationic “anchoring points,” the strength resins appear to need a stoichiometric match.
Under acidic papermaking conditions alum can be used to achieve optimum resin retention, drainage, and dry-strength contribution.
Under alkaline papermaking conditions the same can be achieved by a highly charged polymer, usually containing quaternary amines.
Cautions: Anionic retention aid polymers are probably the slipperiest materials to be found in a paper mill.
Spills of retention aid emulsions should be collected with dry absorbent. Spraying with water will merely spread the problem around.
In the process of waste water treatment, flocculation is regarded as an important purification technique and has been widely applied due to its prominent advantages such as high efficiency, low cost and simple operation compared with other purification techniques.
As a common and widely used flocculant, the synthetic polyelectrolyte, especially the anionic polyacrylamide (APAM) has got more and more attention in waste water treatment because its excellent solid-water separation performance.
On one hand, the particles with opposite charge can be thoroughly neutralized and destablized by the anionic chemical group.
On the other hand, these destabilized particles will be captured by the molecule chain of APAM to agglomerate and form large and compact flocs, and thus flocculation occurs.
During the solid-water separation process, the main mechanisms involved are charge neutralization, bridging and electrostatic patching, which have been demonstrated by many previous studies.
Up to now, a series of anionic polyacrylamide with high flocculation performance have been developed and applied in the waste water treatment.
However, the defect of the APAM, namely, the disordered and random distribution of anionic units in the polymer chain, seriously restricts the further enhancement of the solid-water separation ability.
In addition to the molecular weight (MW) and the density of the anionic monomer, the configuration and the distribution of anionic units also affect the final flocculation performance.
If the anionic units orderly distributes in the polymer chain of APAM to form the anionic microblock structure, the negative charge of the anionic group becomes more centralized and will neutralize the positive charged particles completely, thus increasing the charge neutralization ability
Meanwhile, the strong repulsive force between anionic microblocks are advantageous for the stretch and extension of the polymer chain, and therefore the bridging ability of the polymer is improved.20 Now, the most critical issue is to search for a new approach to prepare the novel APAM with microblock structure, whereas it is incapable for traditional synthesis methods.
Anionic PAM is produced when acrylamide is polymerized with an anionic comonomer.
Water soluble PAMs have been used for decades to facilitate solid liquid separations in wastewater and drinking water treatment, the pulp and paper industry, aquaculture, and many other industrial processes.
Although polymer-based water clarification is a technique that is well established in industrial applications, treatment of construction runoff is a newer and less established use of this technology.
Today there are several anionic PAM-based products marketed for use in construction site sediment management.
These products can be applied for erosion control, clarification of sediment laden runoff, and de-mucking of wet sediment during pond cleanouts.
They are designed to be used in conjunction with other best management practices, as part of a multi-barrier approach, to minimize soil loss and improve settling of suspended sediments.
Application of anionic polyacrylamide:
Industrial wastewater treatment: for suspended particles, less, high concentration, particle with positive charge, the pH of the water is neutral or alkaline water, iron and steel plant wastewater, electroplating wastewater, metallurgical wastewater, coal washing wastewater and sewage treatment, the effect was the best.
Drinking water treatment: many Chinese waterworks water from rivers, sediment and mineral content is high, compared with turbidity, although after precipitation and filtration, still can not meet the requirements and need to adding flocculant, dosage is 1 / 50 of the inorganic flocculant, but the effect is several times the inorganic flocculant for the organic polluted river water, using inorganic flocculants and company of cationic polyacrylamide with better effect to use can be. Starch factory and alcohol plant loss of starch grains recovered: now a lot of a lot of starch factory wastewater containing starch, now cast and anionic polyacrylamide, so that starch particles flocculation, and then precipitate the filter press into a pancake, feed, alcohol plant alcohol can also adopt anionic polyacrylamide dehydration, filter for recovery.
Product Benefits
High performance, high molecular weight anionic polyacrylamide
Excellent for use in wastewater and effluent treatment applications
Ideal for mechanical dewatering
gravity settling
as a coagulant aid
water clarification
filtration
phosphate removal
an aid in Dissolved Air Flotation (DAF) units
Reduces need for inorganic salts
Achieves high solids removal
Economical to use
Application：
1. Materials used for drilling mud additives, can reduce the friction of the drill bit to extend the service life of drill bits to improve the penetration rate and the footage, reduce the time for drilling the plug, the collapse of effective anti-wells, in addition to thickening the water used in flooding, fracturing fluid and selective water shutoff, for Enhanced Oil Recovery Significant Effect;
2. In the mining, coal mining industry can be used for waste water, coal washing waste water clarifier.
3. Used for drinking water purification, municipal sewage sludge, municipal solid waste and industrial effluent;
4. Paper-making industry for the clarification of liquid caustic soda, fiber dispersing agent, can improve the beating, the filler retention agents, paper strengthening agent, can be used to improve the treatment rate and the white water recovery;
5. Used in Textile, Carpet Industry, Sizing, Quick-setting Cement, Synthetic Resin Coating. Photosensitive Polymers, Adhesives, Dispersing Agent, as well as Agricultural Soil Gel, Slurry Stabilizers, Soil Amendments;
6. Oil field water treatment to deal with the recovery of oil.