Effects of Carboxylate-Modified, “Green” Inulin Biopolymers on the Crystal Growth of Calcium Oxalate

Abstract

In this work, the effect of a biodegradable, environmentally friendly polysaccharide-based polycarboxylate, carboxymethyl inulin (CMI), on the crystal growth kinetics of calcium oxalate was studied at 37 °C. CMI is produced by carboxymethylation of inulin, the latter extracted from chicory roots. The spontaneous crystallization method was utilized to investigate the crystallization kinetics of calcium oxalate (CaC 2O 4, CaOx). The experimental results show that the retardation in mass transport in the growth process is controlled by the carboxylation degree of CMI and also its concentration. Our studies also indicate that polymers were effective in directing calcium oxalate crystallization from calcium oxalate monohydrate (COM) to calcium oxalate dihydrate (COD). Comparisons with the effects of polyacrylate (PAA) additive, which was also included in our experiments, show that PAA is a more effective inhibitor than CMI-15 and CMI-20, and comparable to CMI-25.