Introduction
Experimental
Apparatus
Chemicals and sample preparation
Analytical procedures
Results and discussion
The spectrum of RCOOMB in nanocellulose
The binding ratio of MB to –COO− in nanocellulose
The dissociation constant of RCOOMB complex
The selection of the condition to improve the method accuracy
Effect of possible interference on the spectral measurement
Establishment of multi‐wavelength spectroscopic method for measuring carboxyl content
Method evaluation
Test no. | –COOH content, µmol/g | ||||||
---|---|---|---|---|---|---|---|
Sample 1 | Sample 2 | Sample 3 | Sample 4 | Sample 5 | Sample 6 | ||
1 | 820 | 1086 | 732 | 932 | 1223 | 890 | |
2 | 802 | 1048 | 724 | 940 | 1199 | 872 | |
3 | 814 | 1095 | 721 | 956 | 1194 | 882 | |
4 | 932 | 1072 | 713 | 937 | 1260 | 869 | |
5 | 827 | 1116 | 725 | 964 | 1218 | 903 | |
Average | 819 | 1083 | 723 | 946 | 1219 | 883 | |
RSD, % | 1.4 | 2.3 | 0.9 | 1.4 | 2.1 | 1.6 |
Sample type | NaClO dosage to pulp mmol/g | –COOH, µmol/g | Relative difference, % | |
---|---|---|---|---|
Present (n=3) | Reference (n =3) | |||
Bleached kraft pulp | 2.4 | 819 ± 13 | 830 ± 10 | − 1.32 |
4.8 | 1083 ± 9 | 1110 ± 70 | − 2.40 | |
GVL pulp | 2.4 | 723 ± 23 | 700 ± 30 | 3.18 |
4.8 | 1219 ± 15 | 1170 ± 30 | 4.23 |