Effect of polyacrylic acid on direct aqueous mineral carbonation of flue gas desulfurization gypsum

摘要: Abstract We have previously precipitated highly pure calcium carbonate (CaCO3) crystals from a filtered solution extracted in the course of direct mineral carbonation flue gas desulfurization gypsum. However, maximum amount CaCO3 obtained by process was less than 5% thus attempted to manipulate induction period adding polyacrylic acid (PAA), with expectation dissolving more Ca2+ solution. This because it is known inhibit formation CaCO3. The PAA actually found prolong over 1.5 h, addition 2.7 g/L specifically increasing dissolved 60% It also that lowered overall yield via CO2(g) emission, reducing CO2 dissolution. In addition, ammonium ((NH4)2CO3) discovered be usable for producing presence PAA. An in-situ liquid-phase X-ray diffraction revealed sequential calcite amorphous phase on exposure air. morphology comprised twinned pseudo-spherical or dumbbell-shaped crystals, unlike typical rhombohedral without clearly demonstrated precipitation clean FGD gypsum can enhanced additives as better economic viability.