retention aid relationship with aluminum sulfate

Aluminum sulfate manufacturers have reported , aluminum sulfate is paper sizing agent is soil conditioning neutralizer , flocculation and sewage treatment flocculants . The retention aid is used to improve the wire section of paper fibers and fines retention of the Metal stearate  chemical. Then they existed before what kind of relationship do ?
Common retention aids
 Retention aids are commonly modified starch and synthetic resins, retention agents generally also have to accelerate the slurry treatment filter aid performance. There are two main types . ( 1 ) modified starch . From corn , potato , tapioca wet , dry process obtained anion and cation -modified starch. Mainly quaternary ammonium and methyl tin stabilizer  amine -modified cationic starch . ( 2 ) polyacrylamide . Are generally anionic or cationic modified type of product . Anionic polyacrylamide by partial hydrolysis reaction or sulfomethylation reaction. Or by acrylic acid cis -butadiene copolymer derived. Cationic Hoffman is through Mannich reaction or reaction. Also with aminoalkyl methacrylate copolymer obtained .
Aluminum sulfate retention aid
Generally, there are inorganic retention agents such as aluminum sulfate , sodium aluminate ( retention effect chrome oxide  is not significant ) ; cationic starch ; carboxymethyl cellulose ; synthetic resins ( e.g., polyethylene imine , polyacrylamide , polyethylene oxide , polyamides , etc. ) .
  That aluminum sulfate with the fiber retention effect , which means it is a retention aid . This is similar to its role in wastewater treatment . However, its retention effect as polyaluminum chloride and polyacrylamide .