Removal of Methylene Blue from Aqueous Solutions by Using Nance (Byrsonima crassifolia) Seeds and Peels as Natural Biosorbents

Table 4

Main functional groups and the FTIR spectra of nance seeds and peels.

Wavelength ()	Type of vibration	Compound	Nance seeds before adsorption	Nance seeds after adsorption (pH 7)	Nance seeds after adsorption (pH 10)	Nance peels before adsorption	Nance peels after adsorption (pH 7)	Nance peels after adsorption (pH 10)
3290	(O-H) ν	Polysaccharides, lignin, phenols	✓	✓	✓	✓	✓	✓
3007–3009	(=CH) ν	Lipids	✓	✓	✓	✓	✓	✓
2924–2923	() ν, a; (CH3)ν, a	Lipids, lignin, carboxylic acids, carotenoids	✓	✓	✓	✓	✓	✓
2854	() ν, s; (CH3)ν, a	Lipids, lignin, carboxylic acids, carotenoids	✓	✓	✓	✓	✓	✓
1743–1744	(C=O) ν	Polyesters, pectin, lignin, phenolic and carboxylic acids, lactones	✓	✓	✓	✓	✓	✓
1627–1630	(C=C) ν	Aromatic compounds, phenols, pectin, and carotenoids	✓	✓	✓
1607	(C=C) ν	Aromatic compounds, phenols, and pectin.				✓	✓	✓
1600	(C=C) ν; (C=N) ν	Methylene blue (aromatic rings)		✓	✓		✓	✓
1455	(C-C)	Aromatic compounds, phenols	✓	✓	✓
1387	(C-H)	Methylene blue (alkane)		✓	✓		✓	✓
1370	(CH2) , oop	Polysaccharides, pectin	✓	✓	✓	✓	✓	✓
1330–1331	(C-N) ν	Methylene blue (amine)		✓	✓		✓	✓
1318	(CH2) , sc	Polysaccharides, pectin	✓	✓	✓	✓	✓	✓
1244–1246	(C-H) , oop	Methylene blue (amine)		✓	✓		✓	✓
1235–1239	(C-O) ν; (O-H)	Polysaccharides, lignin, and pectin	✓	✓	✓	✓	✓	✓
1155–1157	(C-H) ν	Phenols	✓	✓	✓
1147	(C-O) ν	Pectin				✓	✓	✓
1027–1031	(C-O) ν; (C-C) ν	Polysaccharides, pectin, acids	✓	✓	✓	✓	✓	✓
884–890	(C-H)	Methylene blue (aromatic rings)		✓	✓		✓	✓
866	(C-H)	Aromatic compounds	✓	✓	✓	✓	✓	✓

ν: stretching; : bending; s: symmetric; a: asymmetric; oop: out of plane; sc: scissoring.