Preparation of Highly Dispersed CaCO₃ Nanoparticles in a Novel Membrane Dispersion Microreactor by a Chemical Coprecipitation Process

Abstract

A chemical coprecipitation method has been developed for the preparation of CaCO 3 nanoparticles using a novel membrane dispersion microreactor with calcium chloride, sodium carbonate, and calcium hydroxide as the reagents. Compared with the traditional coprecipitation process in a stirred tank reactor, a novel membrane dispersion microreactor has been developed, which makes it easier to control the crystal size. The effects of supersaturation, reaction time, feed flow rate, and reaction temperature on the size of CaCO 3 particles have been investigated. Synthesized CaCO 3 products are characterized by TGA, FT-IR, XRD, SEM, TEM, and BET. The results show that the crystal size of the prepared CaCO 3 in this novel procedure reaches 18.8 nm, and the surface area reaches 45.94 m 2 /g. Compared with traditional methods, the membrane dispersed process is of important application value because of its smaller mean particle size, lower cost, and higher efficiency. Furthermore, the application scope is more extensive because of no additional additives.

Powdered activated carbon (PAC)-assisted peroxymonosulfate activation for efficient urea elimination in ultrapure water production from reclaimed water

“…Also, peaks at 32.2°, 37.4°, 53.9°, and 67.5° were ascribed to the (111), (200), (220), and (222) of the calcium oxide (CaO) 23 . Furthermore, the peaks at 18.0°, 34.0°, and 47.0° were observed, corresponding to the (001), (101), and (102) of the calcium hydroxide (Ca(OH) 2 ) and peaks at 23.0°, 29.3°, and 39.4° corresponded to the (012), (104), and (113) of the calcium carbonate (CaCO 3 ) 24 , 25 . Based on this XRD analysis, it is evident that the PAC contains various crystalline calcium compounds as impurities.…”

Removal of the Basic and Diazo Dyes from Aqueous Solution by the Frustules of Halamphora cf. salinicola (Bacillariophyta)

“…The results indicated the presence of amorphous silica in the sample, seen as a continuous elevation in the 2θ range from 10° to 35° [ 96 ]. Moreover, the results provided evidence for the presence of impurities in the biosilica sample: the pattern revealed the presence of calcium carbonate in the form of both vaterite and calcite [ 97 ].…”

“…Three stages could be distinguished in the TGA curve: the first one is related to the release of adsorbed water, the second one came from the decomposition of organic residue [ 98 ], and the third one indicates the decomposition of carbonaceous salts [ 98 , 99 , 100 ]. A more precise search revealed that the analysed sample probably had a significant amount of CaCO 3 , as the mass loss in the characteristic temperature range (590–740 °C) was 34.8% [ 97 ]. A further decrease in the mass at higher temperatures may come from the dehydration of the silanol groups.…”

Powdered Activated Carbon (Pac)-Assisted Peroxymonosulfate Activation for Efficient Urea Elimination in Ultrapure Water Production from Reclaimed Water

“…21 Furthermore, the peaks at 18.0°, 34.0°, and 47.0° were observed, corresponding to the (001), (101), and (102) of the calcium hydroxide (Ca(OH) 2 ) and peaks at 23.0°, 29.3°, and 39.4° corresponded to the (012), (104), and (113) of the calcium carbonate (CaCO 3 ). 22,23 Based on this XRD analysis, it is evident that the PAC contains various crystalline calcium compounds as impurities.…”