Carboxymethyl inulin biopolymers: A green alternative for phosphonate calcium carbonate growth inhibitors

Luciaan Boels*, Geert Jan Witkamp

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


There is a growing demand for environmentally friendly alternatives for phosphonate-based crystal growth inhibitors (or antiscalants) used in reverse osmosis desalination, which are nontoxic, biodegradable, and free of phosphorus. The effectiveness of such an alternative, carboxymethyl inulin (CMI) biopolymers, in inhibiting calcium carbonate crystallization (CaCO3) was compared to that of nitrilotris(methylenephosphonic acid) (NTMP) and 1-hydroxyethane-1,1-diphosphonate (HEDP). Their inhibiting effect on the seeded growth of calcite was investigated using the constant composition method at different solution compositions. The values of inhibited growth rates could be related well to a Temkin adsorption isotherm. Compared to HEDP and NTMP, CMI-20 and CMI-25 biopolymers exhibited an equally stronger inhibitory effect on the seeded growth of calcite, despite their different degrees of carboxylation. The ability of the inhibitor molecules to mitigate the spontaneous precipitation of CaCO3 in a synthetic membrane concentrate was investigated as well. The results show that the ability of the biopolymers to mitigate precipitation is controlled by their degree of carboxylation. About 2.7 times more NTMP than CMI-25 is needed to achieve a similar precipitation inhibition. At high concentrations, both NTMP and CMI-25 induced twinning in the precipitating calcite crystals. This demonstrates that CMI biopolymers are effective CaCO 3 growth inhibitors, indicating their potential as a green alternative for phosphonates.

Original languageEnglish (US)
Pages (from-to)4155-4165
Number of pages11
JournalCrystal Growth and Design
Issue number9
StatePublished - Sep 7 2011
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics


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