engleski

Influence of some polysaccharides on the production of calcium carbonate filler particles

The influence of water-soluble polysaccharides of high relative molecular masses, Mr, dextrans and starch, on the precipitation of calcium carbonate has been investigated. Calcium carbonate particles were precipitated from a homogeneous system in which calcium hydroxide and carbonic acid were reactants. The charge and the type of the functional groups of polysaccharides varied, as well as their molecular masses and concentrations. In the absence of additives, the rhombohedral calcite and cauliflower-shaped vaterite are obtained. The results also indicate that an amorphous precursor phase appears at the early stage of the precipitation process. In the presence of additives it is observed that: (i) the increase in starch concentration significantly increases the content of vaterite in the final precipitate, (ii) the addition of anionic dextran considerably alters the morphology of vaterite and of calcite, and (iii) the addition of non-ionic dextran results in the formation of calcite as a predominant solid phase. The crystal-size of the so formed calcite reduces by increasing Mr of neutral dextran.

Characterization ; Crystal morphology ; Additives ; Growth from solution ; Calcium carbonates

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