From plant biowaste to green and sustainable acid-base indicators: Extraction, phytochemical screening, and quantum simulation

Natural plant extracts have attracted a lot of interest lately because of their varied chemical composition and their uses in a range of scientific domains. In order to provide an environmentally benign substitute for synthetic indicators, this study investigates the use of plant wastes (including leaf extracts from Aspilia, fig, pomegranate, lemon, and flower extracts from Ixora coccinea, Mussaenda philippica, and Ruellia tuberosa) as acid-base indicators. The plant extracts were characterized and classified using UV–Vis, FT-IR, FESEM, physical characteristics (density, viscosity, surface tension and refractive index), and qualitative phytochemical screening. The presence of an absorption band in the range of 245 to 247 nm in the UV–Vis spectra corresponds to n → π* transitions. The chromophore groups in the extracts can change electron transitions (n–π*) and rearrange based on pH in the aqueous environment. FT-IR spectra clearly show the hydroxyl and carbonyl groups in the extract moieties, which vary their structure in basic and acidic environments and affect the extract colour. SEM results shows that, the presence of various components in their moiety is the cause of the variance in the morphology of plant extracts. Phytochemical parameters of plant biowaste extracts were screened, classified, and tabulated providing a short library of practical feasibilities tested over a wide acidic-basic interval. In Density Functional Theory (DFT) research, a low energy gap (HOMO-LUMO gap) shows that a molecule can be activated more readily by absorbing a photon of light. The titrimetric analysis shows that the endpoint obtained from the synthetic indicator (phenolphthalein) coincides with the endpoint of extracts with less error % values (1.58–4.54), means that plant extracts were promising as a substitute biomass for acid-base titrations. The particular plant leaves and flowers used are affordable, readily available, simple to prepare, practical, environmentally friendly, and accurate for acid-base titrations.