Extraction of Green Acid-Base Indicators From Acanthus Pubescens Flower for Use in the School Laboratory

The use of Acanthus pubescens flower extracts as natural eco-friendly substitutes for synthetic acid base indicators is experimentally confirmed. In this study, it is indicated that ethanolic and acidified ethanol extracts of Acanthus pubescens flower are good replacements to phenolphthalein, bromothymol blue and methyl red in acid-base titrations involving a strong acid versus strong base and a strong acid versus weak base. They can also be used as effective substitutes to phenolphthalein in a weak acid versus strong base titrations. And also the acidified ethanol extracts can be used in place of phenolphthalein and bromothymol blue while the ethanol extracts can replace methyl red in weak acid versus weak base titrations. It is also concluded that the use of Acanthus pubescens flower extract as an indicator in all types of acid base titrations is beneficial because of its economy, eco-friendly nature, ease of preparation, availability, simplicity, non-carcinogenicity, precision and accuracy of results.