STM Article Repository

In Nigeria, the most commonly used indicator for acid-base titration is synthetic indicator, which is non biodegradable when exposed to the environment. The need to develop acid-base indicators from natural sources to serve as an effective alternative for synthetic indicators is the demand for environment green chemistry. This research work is aimed at the extraction, phytochemical screening, UV/visible spectroscopic analysis of different extracts of red and white kola nuts and application of the extracts as eco-friendly, cost effective and sustainable indicators for acid- base titrations. Extraction was done for 24 hours using acetone, ethanol, cold and hot water separately. The results revealed that all the extracts contained varying amount of phytochemicals, except anthraquinone and phlobatannins which were absents in all the extracts. UV/visible spectroscopic analysis carried out at 600 nm showed that all the extracts have varying absorbance in acidic (HCl) and basic (NaOH) mediums. The potentials of the acid-base indicator of the extracts were evaluated using the titrimetric reactions of strong acid/strong base (HCl/NaOH), strong acid/week base (HCl/NH4OH), week acid/strong base (CH3COOH /NaOH) and week acid/week base (CH3COOH/ NH4OH). The results revealed that the extracts of red kola nut give remarkable colour changes in the titration of strong acid/strong base and strong acid/ weak base. While white kola nut extracts showed remarkable colour changes for all titrations, except in the titration of weak acid with strong base using ethanol and hot water extracts. However, kola nuts extracts which are non toxic, environmentally friendly and biodegradable can serve as effective alternative to synthetic indicator for acid-base titrations.