Skip to Main Content

FTIR was used to investigate the surface functional groups of WSH before and after biosorption. The details of the assignment of bands due to the functional groups present on the surface of the biomass before and after biosorption are given in Table 1. Different adsorption mechanisms including complexation, ion exchange, and electrostatic attraction may be involved in the biosorption process, and these processes depend on the functional groups on the surface of the biomass. In the present study, the broad peak around 3,388 cm−1 was assigned to the presence of -OH or -NH groups on the WSH surface, 1,038 cm−1 shows C-O groups, 1,639 cm−1 shows C = O, the peak at 2,911 cm−1 is due to C-H vibration of CH3 groups, 3,159 cm−1 and 3,029 cm−1 show the vibration of the aromatics. O-H, C = O, C-O, C-H and N-H were identified as being involved in Pb (II) ions binding to the WSH surface due to the shift in the spectra band after adsorption.

Table 1

FTIR spectra characteristics of walnut shell before and after biosorption and the corresponding possible groups

WSH (cm−1)WSH with Pb (II) (cm−1)Vibration type
3,388 3,394 Carboxylic/OH 
3,123 3,123 C-H stretch 
3,070 3,068 Aromatics/C-H stretch 
2,929 2,929 C-H saturated 
1,639 1,615 Carboxylic/C = O 
1,509 1,503 N-H stretch 
1,450 1,421 C-H stretch 
1,262 1,382 -C-O stretch 
1,038 1,056 -C-O stretch 
873 872 Phosphoryl groups 
785 779 C-H out of plane 
WSH (cm−1)WSH with Pb (II) (cm−1)Vibration type
3,388 3,394 Carboxylic/OH 
3,123 3,123 C-H stretch 
3,070 3,068 Aromatics/C-H stretch 
2,929 2,929 C-H saturated 
1,639 1,615 Carboxylic/C = O 
1,509 1,503 N-H stretch 
1,450 1,421 C-H stretch 
1,262 1,382 -C-O stretch 
1,038 1,056 -C-O stretch 
873 872 Phosphoryl groups 
785 779 C-H out of plane 

Close Modal

or Create an Account

Close Modal
Close Modal