The Effect of Carbonation Conditions on the Properties of Carbohydrate-Calcium Carbonate Hybrid Pigments

Abstract

The influence of two polysaccharides, native corn starch and carboxymethyl cellulose (CMC), on the precipitation of calcium carbonate was examined by utilizing two different carbonation processes. In a batch process, carbon dioxide gas was fed through calcium hydroxide slurry at pH 11.5 to 12.0. The reaction was complete when the pH had been decreased to 7. In a fed-batch reaction, the carbon dioxide was dissolved in water while calcium hydroxide was pumped into the water, maintaining a constant pH of 6.0±0.5. Scanning electron microscopy, particle size analysis, and specific surface area analysis were used to characterize the structure of the precipitated calcium carbonate (PCC) pigments. In application testing, the impact of modified pigments on paper properties was examined. The results showed that carbohydrates can significantly affect the crystallization of calcium carbonate, but the influence depends on the precipitation conditions and the type and concentration of the carbohydrate added. The starch-modified PCC, produced by the fed-batch reaction, improved the mechanical properties of the paper, whereas CMCmodified PCC yielded paper with good surface and optical performance but weakened strength properties.

Controlling Calcium Carbonate Particle Morphology, Size, and Molecular Order Using Silicate

“…Many efforts to improve reproducibility and control the calcium carbonate properties included the addition of various excipients to the precipitation reaction. When used as a pigment material, the addition of CMC was shown to affect calcium carbonate particle morphology, improve optical performance, and reduce particle mechanical strength, which can be further improved by supplementation with corn starch [18]. In another study, CMC was shown to induce spherical particle formation [14] and contribute negative charges, thus making the particles suitable as templates for LbL deposition [12].…”

Structural evaluation of chitosan-modified precipitated calcium carbonate composite fillers for papermaking applications

“…Interestingly, handsheets fabricated with chitosan-induced aggregated fillers are seen to improve tensile strength by 8.2% compared to native ones. Enhancement or negative impact of paper strength with different pre-flocs or bio-based composite mineral fillers is well verified by many authors [4,8,60].…”

“…Industrial low-cost native starch or cationic starch is a widely accepted biopolymer in filler modification among various researchers as this hydrogen bonding polymer can develop strong bonds with pulp fibers when dried after starch/mineral composite fillers are added to the furnish. Another approach to fabricate these bio-based composite fillers with paper sheet is in situ crystallization of calcium carbonate in the presence of biopolymers [8]. But there are certain limitations associated with starch such as consumption of extra chemicals during the coating process, loss of cationicity at alkaline pH, sensitivity to water and its prone to microbial attack [9].…”

“…Crystallization of calcium carbonate starts with nucleation and crystal growth takes place either by aggregation or by phase transformation mechanism [21]. Thus, crystallization of PCC particles is tailored by manipulating supersaturation, reactant feed, temperature or with some additives to acquire desired properties required for paper [8]. The templating action of many polymers in controlling the calcium carbonate crystal growth and their orientation has been discussed extensively [22][23][24].…”