RECOVERY OF CALCIUM ACONITATE FROM EFFLUENTS FROM CANE SUGAR PRODUCTION WITH ION-EXCHANGE RESINS

The demineralization of sugar-cane syrup diluted to 30-degrees-Brix with ion-exchange resins produces a heavily polluted regeneration effluent (COD 36600 mg/litre). The recovery of aconitic acid produces a reduction of the pollution caused by such effluents and provides a raw material useful for the chemical industry. The regeneration eluate from anionic resins is concentrated to increase its aconitic acid content to 3.4%, and the acid is precipitated as tricalcium aconitate, with a 92% yield, by adding a 10% excess of calcium chloride at pH 7 and 90-degrees-C. The pollution abatement achieved by this technique on less acidic regeneration eluates, provided methanol is added, is also of interest. However, the precipitate which is then recovered has a low aconitic acid content.