Introduction
Materials and laboratory equipment
Cotton fibers
Dyes
Chemical reagents
Laboratory equipment
Methodology
Preparation of cotton fibers (CFs)
Preparation of aminated cotton fibers (ACFs)
Research on the influence of solution pH on dye sorption efficiency
Research on dye sorption kinetics
Research on the maximum sorption capacity against dyes
Calculation methods
Results and discussion
Characteristics of cotton and aminated cotton FTIR spectra
Carbon and nitrogen content
Influence of solution pH on dye sorption efficiency
Kinetics of dyes sorption
Dye | Sorbent | Conc. of dye | Pseudo-first order model | Pseudo-second order model | Exp. data | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|
qe.cal | K1 | R2 | χ2 | qe.cal | K2 | R2 | χ2 | qe.exp | |||
(mg/L) | (mg/g) | (1/min) | – | – | (mg/g) | (g/mg*min) | – | – | (mmol/g) | ||
RB5 | CFs | 50 | 2.49 | 0.045 | 0.988 | 0.047 | 2.78 | 0.021 | 0.994 | 0.046 | 2.62 |
100 | 2.65 | 0.051 | 0.988 | 0.064 | 2.92 | 0.025 | 0.998 | 0.010 | 2.78 | ||
250 | 2.77 | 0.060 | 0.986 | 0.084 | 3.03 | 0.028 | 0.999 | 0.006 | 2.89 | ||
ACFs | 50 | 27.20 | 0.127 | 0.963 | 1.375 | 28.96 | 0.007 | 0.996 | 0.135 | 28.52 | |
100 | 33.28 | 0.178 | 0.991 | 0.294 | 34.85 | 0.009 | 0.995 | 0.235 | 34.44 | ||
250 | 35.97 | 0.188 | 0.985 | 0.535 | 37.66 | 0.009 | 0.998 | 0.099 | 37.64 | ||
RY84 | CFs | 50 | 12.61 | 0.097 | 0.949 | 0.951 | 13.59 | 0.011 | 0.992 | 0.130 | 13.45 |
100 | 14.55 | 0.168 | 0.963 | 0.570 | 15.38 | 0.018 | 0.994 | 0.092 | 15.31 | ||
250 | 16.15 | 0.184 | 0.955 | 0.853 | 16.98 | 0.019 | 0.991 | 0.178 | 17.03 | ||
ACFs | 50 | 32.91 | 0.066 | 0.960 | 2.687 | 35.77 | 0.003 | 0.994 | 0.315 | 34.21 | |
100 | 35.59 | 0.104 | 0.966 | 1.767 | 38.17 | 0.004 | 0.997 | 0.139 | 37.45 | ||
250 | 43.55 | 0.144 | 0.988 | 0.639 | 45.92 | 0.005 | 0.998 | 0.078 | 44.54 | ||
AR18 | CFs | 50 | 3.83 | 0.095 | 0.968 | 0.176 | 4.13 | 0.035 | 0.997 | 0.014 | 4.09 |
100 | 4.27 | 0.098 | 0.965 | 0.217 | 4.59 | 0.032 | 0.997 | 0.017 | 4.53 | ||
250 | 4.74 | 0.105 | 0.981 | 0.133 | 5.07 | 0.032 | 0.999 | 0.001 | 4.97 | ||
ACFs | 50 | 35.61 | 0.176 | 0.959 | 1.588 | 37.57 | 0.008 | 0.994 | 0.251 | 37.61 | |
100 | 47.07 | 0.278 | 0.985 | 0.666 | 48.57 | 0.012 | 0.999 | 0.055 | 48.21 | ||
250 | 50.21 | 0.286 | 0.983 | 0.813 | 51.80 | 0.012 | 0.998 | 0.085 | 52.05 | ||
AY23 | CFs | 50 | 3.15 | 0.132 | 0.977 | 0.082 | 3.35 | 0.061 | 0.996 | 0.018 | 3.33 |
100 | 3.31 | 0.164 | 0.977 | 0.083 | 3.49 | 0.078 | 0.998 | 0.007 | 3.50 | ||
250 | 3.51 | 0.172 | 0.973 | 0.100 | 3.69 | 0.078 | 0.997 | 0.012 | 3.68 | ||
ACFs | 50 | 16.03 | 0.162 | 0.989 | 0.191 | 16.86 | 0.016 | 0.997 | 0.075 | 16.49 | |
100 | 17.08 | 0.212 | 0.994 | 0.110 | 17.74 | 0.023 | 0.998 | 0.030 | 17.44 | ||
250 | 19.16 | 0.213 | 0.989 | 0.204 | 19.94 | 0.020 | 0.999 | 0.023 | 19.77 |
Dye | Sorbent | Conc. of dye | The first phase of sorption | The second phase of sorption | ||||
---|---|---|---|---|---|---|---|---|
kd1 | Phase duration | R2 | kd2 | Phase duration | R2 | |||
(mg/L) | (mg*g−1*min−0.5) | (min) | – | (mg*g−1*min−0.5) | (min) | – | ||
RB5 | CFs | 50 | 0.3089 | 60 | 0.9700 | 0.0556 | 180 | 0.9442 |
100 | 0.3416 | 60 | 0.9729 | 0.0411 | 180 | 0.9272 | ||
250 | 0.3718 | 60 | 0.9542 | 0.0373 | 180 | 0.9151 | ||
ACFs | 50 | 5.1481 | 20 | 0.9538 | 0.8762 | 100 | 0.9559 | |
100 | 8.8986 | 10 | 0.9999 | 0.6725 | 110 | 0.8949 | ||
250 | 9.6219 | 10 | 0.9538 | 0.6685 | 110 | 0.9739 | ||
RY84 | CFs | 50 | 2.2608 | 30 | 0.9690 | 0.2182 | 210 | 0.9590 |
100 | 3.7609 | 20 | 0.9951 | 0.2188 | 220 | 0.8453 | ||
250 | 4.0685 | 20 | 0.9484 | 0.1922 | 220 | 0.8763 | ||
ACFs | 50 | 5.3381 | 20 | 0.9975 | 1.7412 | 100 | 0.9794 | |
100 | 7.6572 | 10 | 0.9998 | 1.3256 | 90 | 0.9119 | ||
250 | 10.446 | 10 | 0.9901 | 0.8733 | 90 | 0.8293 | ||
AR18 | CFs | 50 | 0.6184 | 30 | 0.9653 | 0.0683 | 210 | 0.8814 |
100 | 0.6792 | 30 | 0.9544 | 0.0616 | 210 | 0.8654 | ||
250 | 0.7815 | 30 | 0.9619 | 0.0500 | 210 | 0.9141 | ||
ACFs | 50 | 9.1367 | 10 | 0.9818 | 0.9938 | 110 | 0.9790 | |
100 | 13.713 | 10 | 0.9641 | 0.6704 | 110 | 0.9590 | ||
250 | 14.620 | 10 | 0.9568 | 0.6444 | 110 | 0.9418 | ||
AY23 | CFs | 50 | 0.6367 | 20 | 0.9690 | 0.0529 | 220 | 0.9135 |
100 | 0.6747 | 20 | 0.9391 | 0.0471 | 220 | 0.8570 | ||
250 | 0.7092 | 20 | 0.9227 | 0.0416 | 220 | 0.9136 | ||
ACFs | 50 | 4.1106 | 10 | 0.9999 | 0.3047 | 110 | 0.9387 | |
100 | 4.7186 | 10 | 0.9914 | 0.3007 | 110 | 0.8605 | ||
250 | 5.2911 | 10 | 0.9896 | 0.2491 | 110 | 0.9859 |
Maximum sorption capacity
Dye | Sorbent | Langmuir model | Freundlich model | ||||||
---|---|---|---|---|---|---|---|---|---|
Qmax | KC | R2 | χ2 | k | n | R2 | χ2 | ||
(mg/g) | (L/mg) | – | – | – | (L/g) | – | – | ||
RB5 | CFs | 2.74 | 0.520 | 0.939 | 0.028 | 1.788 | 0.088 | 0.910 | 0.036 |
ACFs | 36.77 | 0.195 | 0.981 | 3.782 | 12.193 | 0.225 | 0.931 | 5.350 | |
RY84 | CFs | 15.90 | 0.224 | 0.965 | 0.690 | 6.367 | 0.184 | 0.872 | 2.181 |
ACFs | 43.32 | 0.279 | 0.977 | 6.216 | 15.552 | 0.214 | 0.927 | 7.485 | |
AR18 | CFs | 4.70 | 0.169 | 0.935 | 0.130 | 2.002 | 0.168 | 0.912 | 0.219 |
ACFs | 54.23 | 0.137 | 0.993 | 0.918 | 14.536 | 0.264 | 0.878 | 16.585 | |
AY23 | CFs | 3.58 | 0.811 | 0.935 | 0.025 | 2.622 | 0.064 | 0.724 | 0.118 |
ACFs | 19.35 | 0.188 | 0.977 | 0.558 | 7.177 | 0.197 | 0.841 | 3.978 |