Pre-concentration of microalga Euglena gracilis by alkalescent pH treatment and flocculation mechanism of Ca3(PO4)2, Mg3(PO4)2, and derivatives

Table 1 The saturation indices (SI) of the different compounds in the PEM medium by pH 8.5, 25 °C treatment were predicted with Visual MINTEQ software

Compounds	lgIAP	lgKsp	SI^a
Ca₁₀(PO₄)₆(OH)₂	− 20.90	− 44.33	23.43^b
Ca₄H(PO₄)₃·3H₂O	− 34.33	− 47.95	13.63^b
β-Ca₃(PO₄)₂	− 18.41	− 28.92	10.51^b
am₂-Ca₃(PO₄)₂	− 18.41	− 28.25	9.84^b
Mg₃(PO₄)₂	− 14.08	− 23.28	9.20^b
am₁-Ca₃(PO₄)₂	− 18.41	− 25.50	7.09^b
MgHPO₄·3H₂O	− 14.47	− 18.18	3.70^b
CaHPO₄	− 15.92	− 19.28	3.36^b
CaHPO₄·2H₂O	− 15.92	− 19.00	3.08^b
Mg(OH)₂	14.87	18.79	− 3.93^c
MgO	14.87	21.58	− 6.72^c
Ca(OH)₂	13.42	22.70	− 9.28^c
CaO	13.42	32.70	− 19.28^c

^aSI saturation index = lgIAP − lgKsp; ^bSI > 1, oversaturation; ^cSI < 1, undersaturation; IAP ion activity product, K_SP solubility product constant

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