Betaine from natural sources is still preferred over
its synthetic
analogue in secondary industries. It is currently obtained by expensive
separation means, which is one of the main reasons for its high cost.
In this study, reactive extraction of betaine from sugarbeet industry
byproducts, that is, molasses and vinasse, was investigated. Dinonylnaphthalenedisulfonic
acid (DNNDSA) was used as the extraction agent, and the initial concentration
of betaine in the aqueous solutions of byproducts was adjusted to
0.1 M. Although maximum efficiencies were obtained at unadjusted pH
values (pH 6, 5, and 6 for aqueous betaine, molasses, and vinasse
solutions, respectively), the effect of aqueous pH on betaine extraction
was negligible in the range of 2–12. The possible reaction
mechanisms between betaine and DNNDSA under acidic, neutral, and basic
conditions were discussed. Increasing the extractant concentration
significantly increased (especially in the range of 0.1–0.4
M) the yields, and temperature positively (but slightly) affected
betaine extraction. The highest extraction efficiencies (∼71.5,
71, and 67.5% in a single step for aqueous betaine, vinasse, and molasses
solutions, respectively) were obtained with toluene as an organic
phase solvent, and it was followed by dimethyl phthalate, 1-octanol,
or methyl isobutyl ketone, indicating that the efficiency increased
with decreasing polarity. Recoveries from pure betaine solutions were
higher (especially at higher pH values and [DNNDSA] < 0.5 M) than
those from vinasse and molasses solutions, indicating the adverse
influence of byproduct constituents; however, the lower yields were
not due to sucrose. Stripping was affected by the type of organic
phase solvent, and a significant amount (66–91% in single step)
of betaine in the organic phase was transferred to the second aqueous
phase using NaOH as the stripping agent. Reactive extraction has a
great potential for use in betaine recovery due to its high efficiency,
simplicity, low energy demand, and cost.