# Cleaner Processes for Making Laundry Soap from Vegetable Oils and an Essential Oil
## 3 Results and Discussion
### Confirmation of the Presence of Essential Oil in Soap  
3.2.1. FTIR  
Comparisons between soaps without essential oil, considering the standards (CS1 and HS1), formulated by hot and cold saponification, respectively, are shown in Figure 1.  
Figure 1 shows that the heights of the overlapping peaks, from 1561 cm\({}^{-1}\) (C-O stretch), related to the two saponification processes (hot and cold, after 1 month of ripening) are approximately equal, which means that cold saponification is a good option for soap formulation. Other significant peaks appear at 2941 cm\({}^{-1}\) and 2861 cm\({}^{-1}\) (symmetrical, and symmetrical stretching vibration of the methylene -CH\({}_{2}\) group), 2367, 1457 cm\({}^{-1}\) (bending vibrations of the CH\({}_{2}\) and CH\({}_{3}\) aliphatic), 1438 cm\({}^{-1}\) (deformation &C-H), 1396 cm\({}^{-1}\) (bending vibrations of CH\({}_{2}\) groups). These are in agreement with the literature [79].  
The presence of an essential oil in the soap mass can influence the appearance of the FTIR spectrum. In the case of cold saponification, the essential oils used in soap-making do not bring changes to the spectrum compared to the standard (without essential oil) (Figure 2).  
In Figure 3, the presence of essential oils in the hot saponification process brings about changes in the absorption bands in the ranges of 4000-3400 cm\({}^{-1}\) (-OH groups in phenolic compounds or alcohols), 3000-2800 cm\({}^{-1}\) (=C-H, trans and cis, symmetric stretching  
Figure 1: FTIR spectra of standard soaps (CS1 and HS1), made by hot and cold saponification.  
Figure 2: FTIR spectra of soaps formulated by cold saponification.  
C-H) and 1750-1550 cm\({}^{-1}\) (C=O stretching and RHC=CH\({}_{2}\) stretching in cis olefins) and 730 cm\({}^{-1}\). Tea Tree essential oil is rich in terpinene-4-ol and d-limonene, which absorbs strongly at approximately 730 cm\({}^{-1}\) (attributed to aliphatic long chain hydrocarbons), 800 cm\({}^{-1}\) (-HC=CH- (cis), bending (out of plane) specific to olefins), 885 cm\({}^{-1}\) (=CH\({}_{2}\), out of plane deformation), 955 cm\({}^{-1}\) (-HC=CH- (trans), out of plane deformation for disubstituted olefins) and between 2975 and 2925 cm\({}^{-1}\) (corresponding to stretching vibration in the CH\({}_{2}\) aliphatic chain) [80]. Other weaker absorptions appear in the domains of 1022-1068 cm\({}^{-1}\) (-C=O, stretching of ester groups), 1126 -1161 cm\({}^{-1}\) (-C-O, C-OH, stretching, bending), 1379 cm\({}^{-1}\) (-dimethyl, out-of-plane deformations in cis olefins), and 1442 -1465 cm\({}^{-1}\) (=CH\({}_{2}\), deformation in plane) are observed [81].  
FTIR analysis of Neem essential oil indicates absorption bands at approximately 3445 cm\({}^{-1}\) (stretching vibrations originated due to stretching of O-H groups for intramolecular hydrogen bond), 1595 cm\({}^{-1}\) (stretching vibrations originated due to aromatic skeleton vibrations involving both C-C stretching), and 1354 cm\({}^{-1}\) (stretching of C-H stretching, CH\({}_{2}\) wagging, CO, C-O bonds of acetyl esters, and C-O stretching) [82].