Preparation of Precipitated Calcium Carbonate from Carbon Mineralization of Raw Biogas with Ca(OH)_2 Solution using Bubble Column Contactor

摘要

Precipitated calcium carbonate (PCC) is one of the versatile materials that can be used in many fields such as in papermaking, glass, rubber, plastic, paint, pharmacy, food, cosmetics, detergent and biomaterials. PCC with different chemical and physical properties such as particle size, specific surface area, morphology, and chemical purity is important for its application. In this work, PCC was synthesized by carbon mineralization of biogas with Ca(OH)_2 solution using a bubble column contactor. Sucrose was added as an additive to increase the conversion to PCC. The bubble column contactor comprises a cylindrical column 7.3 cm in diameter and 100 cm high and is equipped with a perforated plate gas distributor. The effect of concentration of Ca(OH)_2 solution and sucrose concentration to PCC characteristic was investigated in continuous operation. When the pH of the solution has decreased to about 7.0, flow of biogas was terminated. In continuous operation, raw biogas was injected into bottom column through gas distributor, while Ca(OH)_2 solution was sprayed into liquid surface at top column with constant flow rate and liquid height of 50 cm. The outflow solution from the bottom of the column was collected and the pH is measured. PCC in the solution was filtered and dried, and then examined to determine particle size distribution, morphology of particle, and crystallinity using particle size analyzer (PSA), scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The results showed that the effect of additive on the particle size of PCC formed was found to be insignificant. The particle size of PCC formed was around 4-5 μm depend on the amount of additive added.