Green Synthesis and Characterization of Biosilica Produced from Sugarcane Waste Ash

Table 4

Assignments of the IR vibrations of studied samples.

Frequency (cm^−1)	Assignment	Spectra of samples	References
400	Si-O-M (metal impurities bonding)	SWA	[26]
450–455	Si-O-Si symmetric stretching (siloxane group)	All samples	[23–25]
520	Al-O-Si bending vibrations	SWA	[22]
550–560	(Si)-Al-O stretching	BS and BSW	[29]
615	CO2 rocking (acetate group)	BS	[30]
645	CO2 deformation torsion about C-C bond (acetate group)	BS	[30]
690	Si-O-Al deformation	SWA	[21]
780	Si-O stretching showed presence of quartz	SWA	[22]
790–797	Si-O-Si symmetric stretching (siloxane group)	BS and BSW	[24, 25, 27]
925	C-C stretching (acetate group)	BS	[30]
957	Si-OH bending vibrational absorption (silanol group)	BSW	[25, 27]
1050–1070	Si-O-Si asymmetric stretching	All samples	[23, 25, 31]
1415	C-O stretching (acetate group)	BS	[30]
1560	C-O stretching (acetate group)	BS	[30]

SWA = sugarcane waste ash; BS = biosilica; BSW = biosilica washed with water.