A spectroscopic study of the mineral paceite (calcium acetate)

Abstract

A comprehensive spectroscopic analysis consisting of Raman, infrared (IR) and near infrared (NIR) spectroscopy was undertaken on two forms of calcium acetate with differing degrees of hydration. A monohydrate (Ca(CH 3 COO) 2 .H 2 O) and half-hydrate (Ca(CH 3 COO) 2 .0.5H 2 O) species were analysed. Assignments of vibrational bands due to the acetate anion have been made in all three forms of spectroscopy. Thermal analysis of the mineral was undertaken to follow its decomposition under a nitrogen atmosphere. Three major mass loss steps at ~120, 400 and 600 °C were revealed. These mass losses correspond very well to firstly, the loss of co-ordinated water molecules, and then the loss of water from the acetate anion, followed by finally the loss of carbon dioxide from the carbonate mineral to form a stable calcium oxide.

Effect of acid on morphology of calcite during acid enhanced defluoridation

“…Similarly, the XRD spectrum of the precipitate obtained when AA was used (spectra D in Fig. 1) resembles with the reported X-ray spectrum of calcium acetate crystals [42]. The observed formation of the precipitate of calcium citrate on the limestone surface may block further reaction of CA or F À with the limestone.…”

“…3D), three significant mass losses have been observed at 120, 402 and 596 8C. The mass loss at 120 8C can be attributed to evaporation of water molecule followed by loss of carbon dioxide at 402 8C and finally loss of CO 2 to form stable calcium oxide at 596 8C [42]. Thus the curve corresponds to calcium acetate formed by combination of acetate ion and calcium ions dissolved from limestone.…”

“…In the spectra of carboxylate salts the carbonyl stretching frequency is lowered from the value found for the parent carboxylic acid because the O-C-O bond possesses more single-bond character due to resonance [46]. The IR frequencies of the precipitate obtained with citric acid and acetic acid have been found to be similar to the IR of laboratory grade calcium citrate and reported IR of calcium acetate [42] indicating the precipitates to be calcium citrate and calcium acetate, respectively.…”

Resistance of geopolymer and Portland cement based systems to silage effluent attack

“… The formation of a band at 1556 cm -1 due to C-O stretching vibrations of calcium acetate is evident in PCp after 12 months [57]. This band is only present at the edge of the PCp samples in contact with the effluent.…”

Synthesis of blue-luminescent CaNb₂O₆ by using a biphasic liquid method at low temperatures

“…It is known that calcium acetate has differing degree of hydration, depending on the sample history. 19), 20) The exact hydration number (n) could not be determined in the precipitates because they were actually a mixture, as mentioned below. The hump in the pattern may be related to amorphous niobate gels.…”