Table 3 FTIR spectrum analysis of most important functional groups in malachite green dye solution before and after degradation by R. mucilaginosa AUMC13567 yeast strain

3439.33

–OH or –NH stretch (hydroxyl or amine)

3416.90

O–H stretch (hydrogen-bonded hydroxyl groups)

2924.05

C–H stretch (alkane or aromatic C–H)

2956.18

C–H stretch (alkyl groups)

1721.3

C = O stretch (carbonyl group)

2924.37

C–H stretch (alkyl groups)

1614.81

C = C stretch (aromatic ring), or C = N stretch

2853.54

C–H stretch (alkyl groups)

1585.7

Aromatic C = C stretch or N–H bend

1735.35

C = O stretch (carbonyl group)

1445.4

C–H bending (CH₂ or CH₃)

1650.72

C = C stretch (conjugated alkenes)

1373.20

CH₃ symmetric bending

1464.16

C–H bending (methylene groups)

1172.27

C–N or C–O stretch

1377.5

C–H bending (methyl groups)

941.29

C–H out-of-plane bending (aromatic ring)

1283.76

C–O stretch (ethers, esters)

832.71

C–H out-of-plane bending (aromatic)

722.50

C–H out-of-plane bending (aromatic rings)

725.19

C–H bending (possibly –(CH₂)_n – rocking)

-

-