Plant tannins have the ability to form stable complexes with metal ions, while microporous membranes have low pressure drop and high flux characteristics. Combining these two materials, a new type of tannin-immobilized membrane (M-TAN) adsorption material has been developed. The PA-BWT, PVDF-BWT, CELL -BWT, and PA-AA-BWT were prepared using different types of microporous membranes as substrates, which maintained the porous structure of the membranes and had the characteristics of high flux and fast filtration rate. The surface contact angle and pure water flux analysis showed that the introduction of tannin with multi-phenolic hydroxyl groups increased the hydrophilicity and water flux of the M-TANs. The adsorption performance shows that the adsorption capacity of four kinds of M-TANs for UO22+is in the order of PA-BWT > PA-AA-BWT > PVDF-BWT > CELL-BWT, and PA-BWT has the largest adsorption capacity of 0.398 mmol g−1. In addition, the adsorption isothermal and kinetic data of PA-BWT were well fitted by the Langmuir equation and the Elovich model, respectively. The negative values of ΔG for UO22+adsorption on PA-BWT indicated that adsorption is a spontaneous and favorable process. These facts indicate that PA-BWT can be used as a low-cost adsorbent for effective removal of UO22+from aqueous solutions.Keywords:plant tannins;microporous membranes;immobilized tannins;membrane adsorption
Aaron Albert Aryee,Chenping Gao,Runping Han,Lingbo Qu
The adverse effects of eutrophication have prompted the use of various remediation techniques for phosphate (PO 4 3– ) removal owing to it being the major causative agent. Herein, the influence of different solvents and ratios of 2-aminoterepthalic acid on the efficiency of magnetic biomass metal–organic framework composites based on the in situ growth of NH 2 -MIL-101 (Fe) onto magnetized peanut husks towards PO 4 3– removal was assessed via the adsorption technique. The magnetic biocomposite labelled as MPN@NH 2 -MIL-101 (Fe) exhibited the best efficiency owing to its mesoporous structures and presence of abundant oxygen and nitrogen possessing functional groups. Adsorption results confirmed MPN@NH 2 -MIL-101 (Fe) to have a high adsorption capacity of (14.0 ± 0.3) mg·L −1 at a PO 4 3− concentration of 20 mg·L −1 with an associated high stability within pH 2–10. The adsorption kinetics for the process was well described by both Elovich and pseudo-second-order kinetic models and was mediated by both internal diffusion and liquid film diffusion. The Temkin and Freundlich models fitted the equilibrium data well signifying occurrence of both physical and chemical adsorption on a heterogeneous surface. It is concluded that MPN@NH 2 -MIL-101 (Fe) is a promising adsorbent for the effective removal of phosphate from a water body.
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