Yeyuan Feng,Xiaorong Meng,Zhenpeng Wu,Jin Chen,Chi Sun,Shanshan Huo
Heavy metal pollution poses a serious threat to human health. Positively charged nanofiltration membranes show excellent application prospects in the field of heavy metal removal due to the combined effect of electrostatic repulsion and size sieving. Here, molybdenum disulfide (MoS 2 ) nanosheets were dispersed in aqueous solution polyethyleneimine (PEI) by virtue of the adhesion effect of tannic acid (TA). Positively charged polyurea NF membranes (TSPU) were prepared by interfacial polymerization of aqueous phase PEI/TA-MoS 2 and organic phase 2,4-toluene diisocyanate (TDI). The surface of the optimized membrane TSPU-0.015 showed better hydrophilicity, the water contact angle was 74.53°, and the functional layer thickness of TSPU-0.015 was 114.8 nm. TSPU-0.015 interface was positively charged (IEP TSPU - 0.015 = 5.62), so the rejection of magnesium salts is significantly higher than that of sodium salts. It shows a retention performance of more than 99% for high-valent heavy metal ions such as Fe 3+ and Cu 2+ , and the retention for Cd 2+ is as high as 92.53%. The permeation flux of TSPU-0.015 is 2.88 times higher than that of undoped MoS 2 (TSPU-0), and the flux to MgSO 4 solution reaches 34.5 L/m 2 ·h (6 bar, R (MgSO4) = 93.18%). TSPU has long-term stable operation and excellent anti-pollution properties, showing wide application potential in the fields of inorganic salt separation and heavy metal pollution.
Achieving robust underwater adhesion by bioadhesives remains a challenge due to interfacial water. Herein a coacervate-to-hydrogel strategy to enhance interfacial water repulsion and bulk adhesion of bioadhesives is reported. The polyethyleneimine/thioctic acid (PEI/TA) coacervate is deposited onto underwater substrates, which can effectively repel interfacial water and completely spread into substrate surface irregularities due to its liquid and water-immiscible nature. The physical interactions between coacervate and substrate can further enhance interfacial adhesion. Furthermore, driven by the spontaneous hydrophobic aggregation of TA molecules and strong electrostatic interaction between PEI and TA, the coacervate can turn into a hydrogel in situ within minutes without additional stimuli to develop enhanced matrix cohesion and robust bulk adhesion on diverse underwater substrates. Molecular dynamics simulations further reveal atomistic details of the formation and wet adhesion of the PEI/TA coacervate via multimode physical interactions. Lastly, it is demonstrated that the PEI/TA coacervate-derived hydrogel can effectively repel blood and therefore efficiently deliver the carried growth factors at wound sites, thereby enhancing wound healing in an animal model. The advantages of the PEI/TA coacervate-derived hydrogel including body fluid-immiscibility, strong underwater adhesion, adaptability to fit irregular target sites, and excellent biocompatibility make it a promising bioadhesive for diverse biomedical applications.
Utilization of greywater can relieve the pressure of water scarcity. However, the widespread presence of anionic surfactants in greywater poses threats to the environment and the health of the human and ecosystem. In this study, bioinspired polyethyleneimine-tannic acid (PEI-TA) complexes were innovatively used for coating of corn straw (CS) and the as-prepared PEI-TA modified CS (PEI-TA@CS) was applied for adsorptive removal of the commonly found sodium dodecylbenzene sulfonate (SDBS) in greywater. The adsorption performance of the modified CS was maximized under the following optimized preparation conditions: 5 g/L of PEI concentration with molecular weight of 3000 Da, 0.5 g/L of TA concentration and 3 h of modification time. Investigation of the adsorption conditions showed that adsorption of SDBS on the adsorbent were pH-independent at pH ≤ 7 and the adsorption process reached equilibrium in about 3 h. The pseudo-second-order model and Freundlich model fit well the kinetic and isotherms data, respectively, and the nature of the adsorption was exothermic and spontaneous. Mechanism analysis showed that the adsorption of SDBS was dominated by hydrophobic interactions. With a dosage of 100 mg, PEI-TA@CS could satisfactorily remove 94.95 % of SDBS from its aqueous solution (50 mg/L). Even in the complex synthetic greywater, the removal of SDBS still reached as high as 81.99 %. The overall results indicated that PEI-TA@CS has promising applications in the removal of anionic surfactants from greywater.
危险品化学品经营许可证（带存储）