Fast and efficient removal of caffeine from water using dielectric barrier discharge

Caffeine is a well-known central nervous system stimulant, which can cause anxiety, insomnia and nervousness. Domestic wastes of caffeinated drinks, beverages and chocolates are the major sources for entry of caffeine in the environmental system. Caffeine has been widely detected in natural water resources. The current study describes a method for efficient removal of caffeine from aqueous solution by a laboratory scale dielectric barrier discharge (DBD) in open air. Caffeine concentrations in various sample solutions were monitored by high-performance liquid chromatography, and the degradation products were identified by directly injecting the sample to mass spectrometer. The consequences of varied parameters such as input power, initial concentration and initial pH of the solution on the degradation of caffeine were investigated. Removal efficiency of caffeine from aqueous solution was 72.6% and 96.6% for the initial concentrations of 100 and 1 mu g/mL, respectively, at initial pH 7 after 4 min treatment in DBD plasma system with 60 W input powers. Caffeine removal efficiency was less in acidic solutions (initial pH 4), and insignificant degradation was observed in alkaline solutions (initial pH 10). Furthermore, the degradation of caffeine was also enhanced by increasing the input power in DBD system. The DBD system used in this study has been considered to be fast, effective and economical. It was operated at atmospheric condition in open air without using catalyst, expensive gases or organic solvents, and significant degradation of caffeine was achieved in a short (4 min) treatment time.

Automated summary

The study successfully demonstrated an efficient method for removing caffeine from aqueous solution using a laboratory scale DBD plasma system, achieving removal efficiencies of 72.6% and 96.6% for initial concentrations of 100 and 1 μg/mL, respectively, at an initial pH of 7 with 60 W input power. Caffeine degradation was less effective in acidic solutions and minimal in alkaline solutions, with degradation enhanced by increasing the input power in the DBD system. The DBD system operated effectively without the use of catalysts, expensive gases, or organic solvents, achieving significant degradation of caffeine in a short treatment time (4 min).