Accepted Manuscript Molecular mechanism of anionic dyes adsorption on cationized

ACCEPTED MANUSCRIPT
10 
3.2 Characterization 
3.2.1 FTIR 
FTIR spectra of RH, RHC and CRHC are shown in Fig.1a. For RH, A vibrational 
C–O and C–H strains of cellulose were also detected by bands of 1026 and 897 cm
-1 
[25]. The band in the 1550-1500 cm
-1
region was identified in RH, which is attributed 
to the conjugated aromatic rings and carbonyl groups present in the polyphenolic 
structure of lignin [26]. The band at 1732 cm
-1
was founded in the RH spectrum, 
which is attributed to the acetyl and ester groups in hemicellulose or carboxylic acid 
groups in the ferulic and p-coumeric components of lignin [4]. Compared with RH, 
the spectra of RHC and CRHC showed a better resolution of C–O and C–H groups at 
bands 1026 and 897 cm
-1
. Moreover, the bands at the 1550-1500 cm
-1
region and at 
1732 cm
-1
present in the polyphenolic structure of lignin and hemicellulose 
disappeared. The above results show that the rice husks are separated by alkali 
treatment and bleaching to remove hemicellulose and lignin to obtain purified rice 
husks cellulose [27].
For RHC, the peak at 3328 cm
-1
is attributed to the O–H stretching vibration of 
the hydroxyl groups, 2895 cm
-1
is attributed to C–H stretching vibration of the –CH
2
– 
groups. A series of peaks at 1161 cm
-1
, 1102 cm
-1
, 1028 cm
-1
, 895 cm
-1
are attributed 
to the –COC– group in the cellulose glucose structure. As can be seen from Fig.1a, the 
spectrum of CRHC varies slightly compared to RHC. Its O–H stretching vibration 
band is weaker than RHC and moves from 3328 cm
-1
to 3351 cm
-1
. This may be due 
to the destruction of hydrogen bonds during the modified process. The peak intensity 
of the –CH
2
– group at 2993 and 2845 cm
-1
(vas (CH
2
), vs (CH
2
)) became stronger and 
a shoulder peak occurred compared with RHC. There is a new adsorption peak 
associated with the stretching vibration of C-N band at 1455 cm
−1
. All the results 
indicate that hydroxypropyloctadecyldimethylammonium group was successfully 
grafted onto RHC molecule structure.

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