Collagen/cellulose bead was prepared by the reconstitution of collagen and cellulose (collagen/cellulose mass ratio = 1/6) from 1-ethyl-3-methylimidazolium acetate. Based on this, a novel bio-adsorbent, bayberry tannin immobilized collagen/cellulose (BT-CC) bead, was obtained via the
reaction of collagen with bayberry tannin. The adsorption properties of BT-CC to Cu(II) in aqueous solution were investigated. Results from SEM and XRD indicated the well preservation of structure after the adsorption of Cu(II). Furthermore, the maximum decomposition temperature of BT-CC after
the adsorption of Cu(II) was even increased for ∼7 °C, confirming the stability of BT-CC. The adsorption of Cu(II) on BT-CC displayed pH-dependence and the maximum adsorption was obtained at pH = 5.0. Based on the mass content of collagen, the maximum adsorption capacity of BT-CC was
0.73, 0.96 and 1.12 mmol/g at 298, 308 and 318 K, respectively, according to the experimental adsorption isotherms. In kinetics studies, the adsorption equilibrium at both of 298 and 318 K reached within ∼300 min, and the experimental data could be well fitted by the pseudo-first-order
rate model. Furthermore, good adsorption properties of BT-CC remained after three cycles of adsorption–desorption. These results indicated that high stability, great adsorption capacity and good reusability of BT-CC as the adsorbent to Cu(II) could be obtained.
Hong Chen,Jianhui Lin,Ning Zhang,Liangzhe Chen,Shuiping Zhong,Yao Wang,Wengong Zhang,Qidan Ling
Adsorption is recognized as one of the most promising technologies applied to remove heavy metals from contaminated water. However, the adsorption efficiency often decreases because of the aggregation and loss of adsorbents. Herein, a novel adsorbent was synthesized by intercalation ethylenediaminetetraacetic acid (EDTA) into layered double hydroxides (LDH) and subsequent encapsulated into PAN polymer matrix using electrospinning. The synthesized electrospun nanofiber membrane (MgAl-EDTA-LDH@PAN) was found to combine the advantages of LDH@PAN nanofiber membrane (high surface area, easy to separate, free from aggregation and loss) and EDTA (powerful chelating agent). The adsorption performance of the MgAl-EDTA-LDH@PAN was evaluated using Cu(II) as target metals by varying experimental conditions such as pH, contact time, initial adsorbent dosage, and temperature. The maximum adsorption capacity of MgAl-EDTA-LDH@PAN was 120.77 mg/g with the initial Cu(II) concentrations ranging from 0.6 to 40 mg/L. MgAl-EDTA-LDH@PAN was also used in real industrial contaminated water treatment, and the final effluent was approximate to class-I criteria of the National Wastewater Discharge Standard of China. (GB 8978-1996). In addition, Cu K-edge XAS and XPS analyses were applied for unraveling the adsorptive performance of MgAl-EDTA-LDH@PAN by revealing the molecular-level mechanism of Cu(II) uptake.
A novel 3-lauramide propyl ester-4-amino-1,2,4-triazole-5-thione modified polyacrylic acid resin (LmPATT-reD113), comprising a bi-ligand amide-based triazole-thione moiety and a carboxylic acid moiety, was prepared and employed for the effective removal of Cu(II) from wastewater. The adsorption experiments demonstrated that the maximum adsorption capacity of LmPATT-reD113 for Cu (II) was 191.94 mg/g, which was 3.03 times higher than that of the polyacrylic acid resin (D113). LmPATT-reD113 and D113 had penetration times of 200 and 150 min, and equilibrium times of 1000 and 675 min, respectively. Column adsorption results showed LmPATT-reD113 outperformed D113. After four adsorption–desorption cycles, LmPATT-reD113 maintained superior performance with a desorption efficiency of 93.23 %. The adsorption kinetics and thermodynamics showed that LmPATT-reD113 to Cu(II) followed the pseudo-second-order kinetic and Langmuir isotherm models, with Δ H , Δ S , and Δ G values of 24.836 kJ/mol, 102.187 J/(mol·K) and −3.092kJ/mol at 298.15 K, respectively. Moreover, the adsorption mechanism was investigated using X-ray photoelectron spectroscopy (XPS) and density-functional theory (DFT), the results showed that the affinity of LmPATT-reD113 for Cu(II) mainly originated from the formation of five-membered rings by C=S and C–N complexed with Cu(II) and the formation of porous structure by O=C–NH molecules through intermolecular hydrogen bonding to promote the adsorption of copper.
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