Table 6.

FTIR spectral analysis of Ulva lactuca biomass before and after biosorption of Congo red and Pb²⁺.

Before biosorption		After biosorption		Shift	References
Wave no. (cm−1)	Annotations	Wave no. (cm−1)	Annotations
3917 3905 3890 3868 3854 3841 3806	O–H stretching	3959 3909 3899 3873 3862 3754	O–H stretching	+ 42  + 4  + 9  + 5  + 8 –87	Andrews and Hunt73
3391	O–H hydroxyl group	3441	broad band of OH and NH	+ 50	Widjanarko et al.74, El-Sheekh et al.75
–	–	2974	C–H	–	Khan et al. (2008)76
–	–	2928	C–H	–	Ouhaddouch et al.77
2354	C–H stretching from aromatic group	2359	N–H or C=O stretching vibrations	+ 5	Maaz78, Raman79
1853	C–H stretching in trans HC=CH		–	–	Sun80
1658	C=O, C=N stretching, NH2 bending (amide I and II)	1644	C=O Carbonil	–14	Filip and Hermann81, Byler and Susi82
–	–	1550	Carbonates groups	–	Wilsona et al.83
1443	C–H group (alkyl)	1451	Pure modes of CH2	+ 8	Prosanov and Matvienko86, Pawlukojć et al.87
1329	N–H group	1266	O–H stretching, NH bending (amide III), C=O, carboxylic groups	–63	Greenwood88, Kumari et al.89
1095	C–O stretching	1146 1101	C–O–C C–O ring	+ 51  + 6	Shao and Wei90, Kačuráková et al.91
748	C–H wagging vibration	660	Carboxylic group (COO–) stretching vibration	–88	Da Róz et al.92, Ramaswamy et al.93
618	C–C twisting (protein) (alkanes)	615	C–H group, S–O bends inorganic sulfates	–3	Rehman et al.94, Smidt and Meissl95
422	C=N or O–H stretching	475	S–S band	+ 53	Kong and Shaoning97, Carpenter et al.99