# Application of Polymers as a Tool in Crystallization--A Review
## 2 Basic Research
### New Materials  
#### 3.3.1 Water Treatment Agents  
Polymer-based water treatment agents have recently received much more attention due to their environmental friendliness, widespread availability, and favorable structural features. [PERSON] et al. investigated a novel low-phosphorus copolymer that strongly inhibited calcium sulfate dihydrate scale formation in industrial cooling water treatment [90]. [PERSON] et al. compared the efficiency of three polymeric antiscaltants: poly(aspartic acid-citric acid) (PAACA) copolymer, poly(maleic acid) (PMA), and a compound inhibitor being the mixture of two earlier mentioned ones [91]. The compound inhibitor showed a better inhibition performance than the above two kinds of monomers for calcium phosphate scale prevention. [PERSON] et al. tested poly(citric acid) (PCA) polymer for CaSO\({}_{4}\) scale prevention [92]. They found that the polymer hinders the CaSO\({}_{4}\) scale crystal growth. [PERSON] et al. synthesized a novel scale and corrosion inhibitor--poly(aspartic acid) functionalized with furfurylamine [93]. The inhibition efficiency was close to 100% against CaCO\({}_{3}\), about 96% against Ca\({}_{3}\)(PO\({}_{4}\))\({}_{2}\), and close to 30% for corrosion. [PERSON] et al. developed a new non phosphorous inhibitor against CaCO\({}_{3}\) scale for cooling water systems glutamic-modified polyethercopolymer (AA-APEU) [94]. It was found that this inhibitor exhibited excellent ability to control CaCO\({}_{3}\) scale with an efficiency of about 71.8%. [PERSON] et al. using one-step graft copolymerization prepared starch-_graft_-PAA polymer as a water treatment agent [95]. Its scale-inhibition efficiency against CaCO\({}_{3}\) was equal approximately to 94%. The turbidity reduction was about 97% when it was used as a coagulant for poly-aluminum chloride (PAC) flocculation of hairwork wastewater. [PERSON] et al. investigated CaCO\({}_{3}\) mineralization using cellulose nanocrystal/polymer composites [96]. [PERSON] et al. synthesized a new inhibitor against CaCO\({}_{3}\), which contains carboxylic acid and ether groups [97]. Its scale inhibition efficiency was 95.60% and showed good biodegradability performance. [PERSON] et al. also prepared a modified polyepoxysuccin acid (PESA) scale inhibitor and then applied it for the inhibition of such scales as CaCO\({}_{3}\), CaCO\({}_{4}\), and Ca\({}_{3}\)(PO\({}_{4}\))\({}_{2}\) in cooling water [98]. The polymer exhibited excellent scale inhibition properties against calcium scales. [PERSON] et al. investigated the ability of hyperbranched polyesters involving citric acid and glycerol monomers to inhibit the deposition of inorganic scales [99]. The obtained polymer showed good inhibition efficiency at the elevated temperature, reaching 75% at 100 \({}^{\circ}\)C. [PERSON] and [PERSON] prepared and tested a new non-phosphorus, multipurpose copolymer to control the formation of inorganic calcium scale and to improve the environmental benefits of coal water slurry [100]. The maximum scale inhibition efficiencies for CaCO\({}_{3}\) and CaCO\({}_{4}\) were about 94%. [PERSON] et al. designed the conditioning process that combines crystallization of magnesium ammonium phosphate with organic polymer flocculation [101]. Cationic polyacrylamide formed flocs which were characterized by a larger size and a more compact structure. The proposed method reduces the ammonium nitrogen load in anaerobic digestion liquor and increases the suitability of biosolids as land fertilizers.