Calcium Oxalate and Gallic Acid: Structural Characterization and Process Optimization toward Obtaining High Contents of Calcium Oxalate Monohydrate and Dihydrate

Abstract

The search for an efficient drug or inhibitor in the formation process of kidney stones has been a promising research topic towards reducing the risks of the formation of disease. However, several challenges have been faced in investigating the most common constituents of kidney stones, calcium oxalate and its hydrate forms (COM, COD and COT). This study focuses on the preparation and structural characterization (TG, XRD, FTIR, SEM) of calcium oxalate hydrates in the presence of gallic acid (GA) and by varying operating parameters such as temperature (25 °C, 36.5 °C and 48 °C), pH (5.6, 6.5 and 7.5) and amount of added GA (ranging from 100 mg to 1000 mg). Response surface methodology was applied in order to evaluate the effects of operating parameters in the formation of COM and COD, and for the process optimization towards maximizing their content in samples. The results indicated that GA inhibited the formation of COM (0–100%) and promoted the formation of COD (0 ≤ 99%), while a medium pH and the amount of added GA showed a significant effect in the process of COD formation. In order to investigate the interactions established in the formation process and the possible adsorption between GA and the formed crystals, electrochemical measurements were performed.

Dragon Fruit Foliage: An Agricultural Cellulosic Source to Extract Cellulose Nanomaterials

“…The result is expected for natural lignocellulosic sources. It is important to note that in the spectra of raw DFF, there are diffraction planes at 2-theta of 15 • , 25 • and 37 • , which could assign to the presence of calcium oxalate [34], a mineral existing in DFF materials, as shown in Figure 4. The XRD data also indicated that the inorganic mineral was completely removed while the cellulose structure remained after several chemical and physical treatments.…”

Green Approach in Synthesis of Bio-Inspired Materials

“…Šafranko et.al. [14] proposed the optimal conditions to obtain the maximum content of the two most dominant calcium oxalate hydrate phases (monohydrate, CaC 2 O 4 •H 2 O, COM, and dihydrate, CaC 2 O 4 •2H 2 O, COD) using response surface methodology (RSM). In their study, the influence of temperature, system pH, and the presence of gallic acid on the individual hydrate phase of calcium oxalate formation was investigated.…”