HPAM assisted controllable synthesis of peanut-like CaCO3 in fixed silicate solution A Physicochemical and engineering aspects

Peanut-like CaCO3 was controllable synthesized in 150mg/L silicate solutions with the help of partially hydrolyzed polyacrylamide (HPAM). The polymorph, crystals structure and composition of CaCO3 under different conditions were characterized by scanning electron microscope (SEM), powder X-ray diffraction (pXRD), energy dispersive X-ray analyser (EDX) and so on. By varying the concentrations of HPAM, initial pH and reaction temperature, peanut-like, fusiform-like and hexahedral CaCO3 particles were prepared successfully. The mechanism of stable peanut-like CaCO3 crystallization induced by silica was proposed. It was found that the adsorption of silanol groups on CaCO3 surfaces played a key role during the condensation reactions of silanol groups, which resulted in the peanut shape of CaCO3 crystals. And as a morphological modifier HPAM led to the formation of specific fibrous surface with different shapes by electrostatic interactions.