Removal of High-Concentration Sulfate from Seawater by Ettringite Precipitation

Figure 7

SEM images of the morphology of formed precipitates with the added chemical dosage at Ca : S molar ratios of (a) 2 : 1, (b) 3 : 1, (c) 4 : 1, and (d) 6 : 1, respectively, when the molar ratio of Al : S is 2 : 1; and (e) and (f) present the SEM images of precipitates formed with the chemical dosage of Al : Ca : S at 0.8 : 4 : 1 and 1 : 4 : 1, respectively.

(a)

(b)

(c)

(d)

(e)

(f)