A mechanism for the occurrence of ions in distilled water

Abstract

Solar distillation can be used to produce potable water from contaminated water. However, studies show that ions such as F^- and NO₃^- occur in distillates from solar stills. In order to understand the reasons for this behavior, imaging and distillation experiments were conducted. White dots were seen in the vapor space above the interface of hot water poured into containers. The concentrations of various ions such as F^- and SO₄^2- in the distillates from thermal and solar distillation experiments were roughly comparable when the feed consisted of deionized water and also solutions having fluoride concentrations of 100 and 10000 mg/L. These observations suggest that aerosols enter the distillation setup through leaks and provide nuclei for the condensation of water vapor. The water-soluble component of aerosols dissolves in the drops formed, and some of the drops are transferred to the distillate by buoyancy-driven convection.