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Coagulation                                                                                      223



                         TABLE 9.11
                         Anionic Polymer Structures and Characteristics
                         Polymer                                                   Data


                              CH 2  CH             CH 2  CH

                                    C    O               C   O
                                    NH 2    x            O –     y

                         (a) Acrylamide=acrylate (AcAm=Ac)
                                                                       113 manufacturers, 1335 products a
                              H    H     H    H
                                                                       O– is carboxyl group, affected by pH
                                                                       Commercial example: Magnifloc 835A b
                              C    C     C    C
                                                                       Molecular weight: 15   10 6
                                                                       Charge density: high
                           O  C  O  C    C O  C  O
                                                                       Commercial example: Magnifloc 820A b
                              NH 2  NH  2  O –  NH 2  n                Molecular weight: 6   10 6
                                                                       Charge density: intermediate
                         (b) Polyacrylamide chain b                    Commercial example: Magnifloc 837A b
                                                                       Molecular weight: 15   10 6
                                                                       Charge density: low

                                               n –                     Commercial example: Purifloc A-21 (Dow) b
                              CH 2  CH                                 Molecular weight: 15   10 6
                                                                       Charge density: very high
                                    C
                              HC         CH


                              HC          CH
                                    C
                                    SO 3 –     n

                         (c) Polystyrene sulfonate

                         a
                          National Sanitation Foundation, www.NSF.com, November 27, 2000.
                         b
                           Luttinger (1981).



                                                               9.9.5.2  Polymer Packaging
            TABLE 9.12                                         Polymers may be purchased as solid, for example, powder,
            Nonionic Polymer Structures and Characteristics    beads, flakes, granular, solution or emulsion. Dry polymers
                                                               may absorb moisture and stick to equipment and may dissolve
            Polymer                         Characteristics
                                                               slowly, for example, 15–60 min. Solution polymers are
                                     Commercial name: Magnifloc 905N a
               CH 2  CH              113 manufacturers, 1335 products b  preferred by many because they are convenient to use since
                                     Molecular weight: 15   10 6  metering is simple, as is cleanup. High molecular weight
                     C   O                                     polymers are rarely sold as water solutions, with most being
                                     Charge density: none
                                                               available as powders or as emulsions (Mangravite, 1983,
                                     Commercial name: Purifloc N-17
                     NH 2   n        Molecular weight: 5–10   10 6  p. 5). Emulsion polymers consist of a polymer and water
                                                               suspended in mineral oil, with polymer content 20%–30%
                      a,b            Charge density: none
            Polyacrylamide
                                                               by weight and water content 0%–50% by weight. Such prod-
            a                                                  ucts must be agitated prior to use. The first dilution must be
             Luttinger (1981).
            b                                                  carried out within a specified concentration range, typically
              May (1988).
                                                               about 1 percent product, to ensure complete dissolution of
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