title: A novel approach for continuous synthesis of calcium carbonate using sequential operation of two sonochemical reactors.
abstract: A novel continuous process for the synthesis of calcium carbonate based on precipitation reaction has been developed involving the sequential operation of two sonochemical reactors for the first time. The reactors were also operated as control (conventional approach without ultrasound) to clearly establish the process intensification benefits due to the use of ultrasound. The effect of different operating parameters such as Ca(OH)2concentration, CO2flow rate and Ca(OH)2slurry flow rate on the particle size has been investigated. The obtained calcite particles were characterized using Fourier transform infrared (FTIR), wide angle X-ray diffraction (XRD) and particle size distribution (PSD) analysis. The morphology of the obtained particles was also analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was established that the average particle size obtained in the presence of ultrasound was smaller with much narrow size distribution as compared to the conventional approach. Further, the average particle size was established to decrease with an increase in the Ca(OH)2slurry concentration and CO2flow rate with the optimum conditions giving a particle size of 164nm. The particle size was also influenced by the Ca(OH)2slurry flow rate and under optimum condition of Ca(OH)2slurry flow rate as 24mL/min, particle size of 135nm was obtained. Only calcite phase of CaCO3was observed to be formed as established based on the XRD analysis during both the synthesis approaches confirming the stability of the obtained particles. It was also observed that the shape of the crystals varied with the method of synthesis. Rhombohedral calcite particles were formed in the presence of ultrasound whereas the conventional stirring method resulted in spindle shaped particles. Overall, the utility of the ultrasound assisted approach has been clearly established with novel results based on the use of sonochemical reactors in series.
authors.affiliation: Department of Chemical Engineering, Sinhgad College of Engineering, Vadgaon (BK), Pune 411041, India. Electronic address: srshirsath@gmail.com.
authors.forename: S R
authors.initials: SR
authors.lastname: Shirsath
authors.affiliation: Department of Chemical Engineering, Laxminarayan Institute of Technology, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440033, India.
authors.forename: B A
authors.initials: BA
authors.lastname: Bhanvase
authors.affiliation: Department of Chemical Engineering, National Institute of Technology, Warangal 506004, India. Electronic address: shirishsonawane@rediffmail.com.
authors.forename: S H
authors.initials: SH
authors.lastname: Sonawane
authors.affiliation: Chemical Engineering Department, Institute of Chemical Technology, Mumbai 400019, India.
authors.forename: P R
authors.initials: PR
authors.lastname: Gogate
authors.affiliation: Chemical Engineering Department, Institute of Chemical Technology, Mumbai 400019, India.
authors.forename: A B
authors.initials: AB
authors.lastname: Pandit
keywords: Calcite phase; Carbonization; Morphology; Particle size distribution; Sequential operation; Ultrasound