Bionic-inspired Construction of Zn(4,4'-dipy)(OAc) 2 /Bacterial Cellulose Composite 1 Membrane for Efficient Separation Synergistically Adsorption of Nitrogen and 2 Phosphorus

Phosphorus and nitrogen flow to water leads to eutrophication and depletion of 21 reserves. Bionic-inspired tannin modification is proposed for preparing a tannin- 22 modified La-Zn(4,4'-dipy)(OAc) 2 /bacterial cellulose composite membrane for 23 simultaneous adsorption of total phosphorus and ammonia nitrogen in water. Its 24 physical and chemical properties were characterized by XRD, SEM, FT-IR, TGA and 25 other characterization. La-Zn(4,4'-dipy)(OAc) 2 nanomaterial achieved effective 26 adhesion on the tannin-modified bacterial cellulose membrane. Adsorption experiments 27 showed that the composite membrane can both adsorb total phosphorus and ammonia 28 nitrogen, and adsorption capacity of ammonia nitrogen is better than that of total 29 phosphorus. The maximum adsorption capacities of ammonia nitrogen and total 30 phosphorus are 482.35 mg/g and 374.71 mg/g. In the binary solution, the adsorption 31 capacity of the composite membrane to ammonia nitrogen and total phosphorus 32 decreased, but the adsorption capacity to phosphorus decreased slightly. Results of 33 adsorption experiments showed that the adsorption process of nitrogen and phosphorus 34 by the composite membrane belongs to single-layer adsorption, and the calculation 35 results of the kinetic equation are in accordance with the quasi-second-order, and the 36 adsorption equilibrium of the composite membrane was reached within 360 min. In 37 short, the composite membrane has a better adsorption and separation effect both on 38 ammonia nitrogen and total phosphorus.


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Water eutrophication, driven by rapid population growth has become a threat to 44 human existence and thus regarded as one of most common environmental problems The effect of engineering repair is remarkable. However, harmful ingredients such as 54 large amounts of nutrients and heavy metals may return to the water body and cause 55 secondary pollution. The water diversion will reduce the environmental pressure that 56 restricts the growth and reproduction of algae because of the dilution effect. So, when 57 water diversion is taken, the algae will show a momentum of increasing growth. The Membrane adsorption process has a huge application prospect in the field of 78 environmental governance. Chemical modification requires strict reaction conditions 79 and cumbersome steps, resulting in a higher composition of modified membrane 80 materials. Inspired by the natural adhesion of biological mussels, we use tannic acid 81 (TA) to construct a biomimetic membrane adsorption material.

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TA is a typical natural polyphenol compound with a large number of hydroxyl 83 groups, which can interact with the biopolymer (for example, some proteins, digestive enzymes, carbohydrates and minerals, etc.) to provide more chemical properties for the 85 tannic acid. TA can adhere to a variety of substrates, thanks to its surface catechol and Previously mentioned, controlling TP and ammonia nitrogen in water is an 91 effective way to govern eutrophication. As far as we know, there have been few reports 92 on the selective control of these two substances simultaneously. We use bacterial 93 cellulose (BC) as the membrane substrate due to its excellent pore structure and low     According to the data in Table 1, the first order kinetic model was used to fit the Qm (mg/L) in formula (7) represents the maximum adsorbent adsorption capacity,

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while KL (L/mg) refers to Langmuir binding constant, which depends on temperature 283 and adsorption heat. In formula (8), 1/n represents the Freundlich constant, which 284 depends on the adsorption system. KF (mg/g) is a constant, depending on the 285 characteristics and quantity of the adsorbed material.

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The advantages of adsorption can be determined by calculating the separation 287 factor RL, whose formula is as follows (9) Figure 8 shows that the adsorption effect of tannic acid modified La-Zn(4,4'-293 dipy)(OAc)2/BC composite membrane on ammonia nitrogen is better than that on total phosphorus. According to the data in Table 2, the saturated adsorption capacity of NH4 + -295 N in the binary mixed solution is 466.33 mg/g, while the saturated adsorption capacity phosphorus decreased less than that of ammonia nitrogen.

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According to the fitting data of the Langmuir and Freundlich equations in Table 2   306 and Table 3, Langmuir fitting equation R 2 is greater than the Freundlich fitting equation.

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Therefore, it can be proved that the adsorption of ammonia nitrogen and total 308 phosphorus by tannic acid modified La-Zn(4,4'-dipy)(OAc)2/BC composite membrane 309 is more likely to conform to the Langmuir equation, indicating that it is a monolayer 310 adsorption process. In addition, RL is greater than 0 and less than 1, indicating that the 311 adsorption process of NH + 4 -N and TP by the composite membrane was the preferred 312 adsorption process. hours and rinsed with ultra-pure water for three times before drying. The whole 334 adsorption desorption process was repeated 5 times. As can be seen from Figure 10 The authors declare that they have no competing interests" in this section.

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All the authors have seen the manuscript and approved to submit to your journal.