Absorption of Cu(II) and Zn(II) from Aqueous Solutions onto Biochars Derived from Apple Tree Branches
Abstract
:1. Introduction
2. Materials and Methods
2.1. Biochar Preparation
2.2. Batch Adsorption Experiments
2.2.1. Chemical Reagents
2.2.2. Adsorption Experiments
2.3. Mathematical Models
2.3.1. Kinetics Test
2.3.2. Adsorption Isotherm
2.3.3. Thermodynamics Study
2.4. Statistical Analysis
3. Results and Discussion
3.1. Influence of BC Dosage
3.2. Influence of Solution pH
3.3. Influence of Contact Time and Adsorption Kinetics
3.4. Adsorption Isotherm Studies
3.5. Influence of Temperature and Thermodynamics Study
3.6. Mechanism of Absorption
4. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Sample | BC300 | BC400 | BC500 | BC600 |
---|---|---|---|---|
C (%) | 62.20 | 71.13 | 74.88 | 80.01 |
H (%) | 5.18 | 4.03 | 2.88 | 2.72 |
N (%) | 1.69 | 1.94 | 1.77 | 1.28 |
O (%) | 24.21 | 15.05 | 10.41 | 6.59 |
H/C | 1.00 | 0.68 | 0.46 | 0.41 |
O/C | 0.29 | 0.16 | 0.11 | 0.06 |
Surface area (m2·g−1) | 2.39 | 7.00 | 37.25 | 108.59 |
Ash (%) | 6.72 | 7.85 | 10.06 | 9.41 |
pH (5:1) | 7.48 | 11.42 | 11.62 | 10.60 |
Cation exchange capacity (cmol·g−1) | 44.72 | 64.33 | 66.70 | 18.53 |
Total acidic functional groups (mmol·g−1) | 0.54 | 0.39 | 0.30 | 0.22 |
Surface carboxyl groups (mmol·g−1) | 0.30 | 0.24 | 0.17 | 0.12 |
Surface phenol groups (mmol·g−1) | 0.12 | 0.08 | 0.07 | 0.06 |
Surface lactone groups (mmol·g−1) | 0.12 | 0.06 | 0.05 | 0.04 |
Conditions | Experiment 1 | Experiment 2 | Experiment 3 | Experiment 4 | Experiment 5 |
---|---|---|---|---|---|
Biochar dosage (g L−1) | 1, 3, 5, 10, 20 | 5 | 5 | 5 | 5 |
Initial solution pH | 5 | 2, 3, 4, 5, 6 | 5 | 5 | 5 |
Contact time (min) | 1440 | 1440 | 10, 20, 40, 60, 90, 120, 180, 240, 360,480, 600, 720, 960, 1200, 1440, 1680, 1920, 2400, 2880 | 1440 | 1440 |
Reaction temperature | 25 °C | 25 °C | 25 °C | 25 °C | 25, 30, 35, and 40 °C |
Initial Cu (II) concentration (mg L−1) | 64 | 64 | 64 | 6.4, 12.8, 38.4, 64, 128, 256, 384 | 64 |
Initial Zu (II) concentration (mg L−1) | 65 | 65 | 65 | 6.5, 13, 39, 65, 130, 260, 390 | 65 |
Rotation speed | 180 | 180 | 180 | 180 | 180 |
Metal | Cu | Zn | |||||||
---|---|---|---|---|---|---|---|---|---|
Biochar | BC300 | BC400 | BC500 | BC600 | BC300 | BC400 | BC500 | BC600 | |
qe,exp | 4.96 ± 0.18d | 7.56 ± 0.27c | 9.70 ± 0.33a | 8.87 ± 0.42b | 4.30 ± 0.10d | 5.69 ± 0.13c | 9.11 ± 0.28a | 7.99 ± 0.22b | |
PF order model | qe (mg g−1) | 4.63 ± 0.07d | 7.14 ± 0.10c | 9.23 ± 0.13a | 8.47 ± 0.12b | 4.05 ± 0.06c | 5.30 ± 0.09b | 8.77 ± 0.13a | 7.75 ± 0.11a |
k1 × 10−3 (L·min−1) | 3.49 ± 0.20c | 7.77 ± 0.49b | 13.5 ± 0.94a | 14.36 ± 1.06a | 2.91 ± 0.16c | 5.26 ± 0.37b | 9.14 ± 0.61a | 10.33 ± 0.69a | |
R2 | 0.93 | 0.91 | 0.90 | 0.89 | 0.93 | 0.93 | 0.92 | 0.91 | |
PS order model | qe (mg g−1) | 5.33 ± 0.04d | 7.80 ± 0.02c | 9.86 ± 0.08a | 9.02 ± 0.02b | 4.74 ± 0.03d | 5.93 ± 0.03c | 9.54 ± 0.06a | 8.34 ± 0.04b |
k2 × 10−3(g·mg−1·min−1) | 0.79 ± 0.15c | 1.35 ± 0.14b | 1.99 ± 0.24a | 2.37 ± 0.28a | 0.72 ± 0.06c | 1.14 ± 0.15b | 1.31 ± 0.37ab | 1.79 ± 0.0.34a | |
h (mg·g−1·min−1) | 0.02 ± 0.00c | 0.08 ± 0.01b | 0.19 ± 0.03a | 0.19 ± 0.05a | 0.02 ± 0.00c | 0.04 ± 0.00b | 0.12 ± 0.01a | 0.12 ± 0.02a | |
R2 | 1.00 | 1.00 | 0.99 | 1.00 | 1.00 | 1.00 | 1.00 | 0.99 | |
IPD model | ki (mg·g−1·min−0.5) | 0.10 ± 0.01a | 0.12 ± 0.01a | 0.13 ± 0.02a | 0.11 ± 0.02a | 0.10 ± 0.20ab | 0.10 ± 0.01b | 0.14 ± 0.02a | 0.12 ± 0.02ab |
C | 0.72 ± 0.25c | 2.56 ± 0.48b | 4.59 ± 0.64a | 4.41 ± 0.58a | 0.46 ± 0.02c | 1.35 ± 0.33b | 3.50 ± 0.61a | 3.42 ± 0.55a | |
R2 | 0.87 | 0.73 | 0.64 | 0.65 | 0.90 | 0.81 | 0.71 | 0.67 |
Metal | Biochar | Langmuir Isotherm Model | Freundlich Isotherm Model | ||||||
---|---|---|---|---|---|---|---|---|---|
Qmax (mg·g−1) | b (L·g−1) | R2 | RL, max | RL, min | n | Kf (mg·g−1) | R2 | ||
Cu | BC300 | 5.20 ± 0.23d | 0.08 ± 0.02b | 0.97 | 0.66 ± 0.06a | 0.03 ± 0.01a | 4.35 ± 0.07b | 1.41 ± 0.47b | 0.74 |
BC400 | 9.58 ± 0.18c | 0.10 ± 0.01b | 0.99 | 0.60 ± 0.02a | 0.03 ± 0.01a | 4.17 ± 0.06b | 2.58 ± 0.76ab | 0.80 | |
BC500 | 11.41 ± 0.23a | 0.23 ± 0.02a | 0.99 | 0.41 ± 0.11b | 0.01 ± 0.01a | 5.00 ± 0.06a | 3.94 ± 1.08a | 0.76 | |
BC600 | 10.31 ± 0.50b | 0.12 ± 0.03b | 0.96 | 0.57 ± 0.04a | 0.02 ± 0.01a | 4.55 ± 0.07b | 2.99 ± 0.99a | 0.73 | |
Zn | BC300 | 4.98 ± 0.32c | 0.04 ± 0.01c | 0.95 | 0.79 ± 0.03a | 0.06 ± 0.01a | 3.45 ± 0.08d | 0.93 ± 0.37c | 0.74 |
BC400 | 7.22 ± 0.36b | 0.05 ± 0.01bc | 0.97 | 0.75 ± 0.02a | 0.05 ± 0.01a | 3.70 ± 0.07c | 1.48 ± 0.52bc | 0.80 | |
BC500 | 10.22 ± 0.52a | 0.13 ± 0.03a | 0.96 | 0.54 ± 0.07c | 0.02 ± 0.00c | 4.55 ± 0.07a | 3.10 ± 1.00a | 0.76 | |
BC600 | 9.15 ± 0.63a | 0.09 ± 0.03ab | 0.95 | 0.63 ± 0.01b | 0.03 ± 0.00b | 4.17 ± 0.08b | 2.35 ± 0.88ab | 0.73 |
Heavy Metal | Biochar | ΔG (KJ·mol−1) | ΔH (KJ·mol−1) | ΔS (J·mol−1·K−1) | |||
---|---|---|---|---|---|---|---|
Temperature (°C) | |||||||
25 | 30 | 35 | 40 | ||||
Cu | BC300 | −0.48 ± 0.06a | −0.60 ± 0.01a | −0.72 ± 0.05a | −0.83 ± 0.05a | 6.45 ± 0.43d | 23.28 ± 1.92d |
BC400 | −1.05 ± 0.05b | −1.23 ± 0.09b | −1.41 ± 0.01b | −1.60 ± 0.04b | 9.72 ± 0.86c | 36.16 ± 0.59c | |
BC500 | −1.27 ± 0.04c | −1.54 ± 0.08d | −1.81 ± 0.09c | −2.08 ± 0.06d | 14.78 ± 1.12a | 53.87 ± 2.72a | |
BC600 | −1.13 ± 0.02c | −1.35 ± 0.04c | −1.57 ± 0.05c | −1.79 ± 0.02c | 11.91 ± 0.91b | 43.77 ± 1.21b | |
Zn | BC300 | −0.30 ± 0.06a | −0.40 ± 0.02a | −0.51 ± 0.07a | −0.62 ± 0.03a | 5.93 ± 0.02b | 20.95 ± 0.28c |
BC400 | −0.50 ± 0.07b | −0.66 ± 0.09b | −0.83 ± 0.01b | −0.99 ± 0.03b | 9.28 ± 0.81a | 32.82 ± 0.67b | |
BC500 | −1.14 ± 0.08d | −1.32 ± 0.05d | −1.51 ± 0.02d | −1.70 ± 0.08d | 9.91 ± 0.82a | 37.11 ± 1.37a | |
BC600 | −0.92 ± 0.06c | −1.09 ± 0.06c | −1.26 ± 0.04c | −1.43 ± 0.05c | 9.42 ± 0.76a | 34.72 ± 2.06ab |
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Zhao, S.; Ta, N.; Wang, X. Absorption of Cu(II) and Zn(II) from Aqueous Solutions onto Biochars Derived from Apple Tree Branches. Energies 2020, 13, 3498. https://doi.org/10.3390/en13133498
Zhao S, Ta N, Wang X. Absorption of Cu(II) and Zn(II) from Aqueous Solutions onto Biochars Derived from Apple Tree Branches. Energies. 2020; 13(13):3498. https://doi.org/10.3390/en13133498
Chicago/Turabian StyleZhao, Shixiang, Na Ta, and Xudong Wang. 2020. "Absorption of Cu(II) and Zn(II) from Aqueous Solutions onto Biochars Derived from Apple Tree Branches" Energies 13, no. 13: 3498. https://doi.org/10.3390/en13133498