MethodsX (Jan 2023)
Estimation method for carbonate in natural alkaline soda lake-waters
Abstract
Natural, inland alkaline soda waters form a particular type of saline waters, characterized by a permanent alkaline chemical property. In many cases only the total alkalinity by methyl-orange titration is reported, without phenolphthalein titration. Therefore, a reliable estimation of carbonates from total alkalinity is essential for a precise scientific chemical classification. The concentration of bicarbonate [HCO3‒] can be reliably estimated in waters using the Advanced Speciation Method (ASM) if methyl-orange total alkalinity titration and pH data are available, while the concentration of carbonate [CO32‒] is not reliably estimated by the ASM when interfering factors with acid/base properties (e.g., phosphate, silicate, ammonia, etc.) are present in significant concentrations in natural waters. Therefore, here I present and prove an experimental polynomial function for carbonate estimation with the following equation based on the concentration of bicarbonate:[CO32‒] = -2.878E-7 ± 5.438E-8 × [HCO3‒]2 + 0.069±0.003 × [HCO3‒]This Boros's carbonate estimation method can contribute to a more efficient evaluation of field water samples with several analytical difficulties. • Bicarbonate can be reliably estimated using the Advanced Speciation Method (ASM). • Estimation of the carbonate concentration using ASM in the presence of interfering acid/base factors in alkaline waters. • Experimental polynomial function for reliable carbonate estimation in alkaline soda waters.
