Yang Le, Bi Lulu, Tao Xiuxiu, Shi Lei, Liu Peipei, Lv Quankun, Li Xuede, Li Jie
Anhui Province Key Laboratory of Farm Land Ecological Conservation and Pollution Prevention, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, Anhui, PR China; Hefei Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture, PR China.
Anhui Province Key Laboratory of Farm Land Ecological Conservation and Pollution Prevention, Anhui Agricultural University, 130 Changjiang West Road, Hefei, 230036, Anhui, PR China; Hefei Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture, PR China.
J Environ Manage. 2024 Feb 27;353:120169. doi: 10.1016/j.jenvman.2024.120169. Epub 2024 Jan 29.
Metal-organic frameworks (MOFs) were promising adsorbents for removing antibiotics, but the inherent poor recyclability of MOF powders limits further application. Moreover, the dominant adsorption mechanisms and their quantitative assessment are less studied. Here, ultrahigh adsorption capacities of 821.51 and 931.87 mg g for tetracycline (TC) and oxytetracycline (OTC), respectively, were realised by a novel adsorbents (biochar loaded with MIL-88B(Fe), denoted as BC@MIL-88B(Fe)), which were further immobilised in a 3D porous gelatin (GA) substrate. The obtained BCM/GA showed superior adsorption performance under wide pH ranges and under the interference of humic acid. Moreover, it can survive >8 cycles and even maintain high adsorption efficiency in different actual water samples. Notably, BCM/GA can selectively remove tetracyclines in a multivariate system containing other kinds of antibiotics and from a dynamic adsorption system. Most importantly, the results of X-ray photoelectron spectroscopy, 2D Fourier transform infrared correlation spectroscopy (2D-FTIR-COS) and density functional theory techniques revealed that (1) for TC adsorption, at pH < 4.0, the contribution of complexation was 25 %-45 %, whereas pore filling and hydrogen bonding accounted for 39 %-72 % of the total uptake. At 4.0 < pH < 10.0, the contribution of complexation increased to 60 %-82 %, whereas electrostatic attraction and π-π interaction were 4 %-13 % and 2 %-10 %, respectively. (2) For OTC adsorption, complexation was dominant at 3.0 < pH < 10.0, accounting for 55 %-86 % of the total uptake, and electrostatic attraction and π-π interactions caused 3 %-10 % and 3 %-15 %, respectively. (3) At pH > 10.0, pore filling dominated TC and OTC adsorption. Finally, the reaction sequences of the main adsorption mechanisms were also probed by 2D-FTIR-COS. This work solves the poor recyclability of MOF powders and provides a mechanistic insight into antibiotic removal by MOFs.
金属有机框架材料（MOFs）是用于去除抗生素的有前景的吸附剂，但MOF粉末固有的可回收性差限制了其进一步应用。此外，主要的吸附机制及其定量评估研究较少。在此，通过一种新型吸附剂（负载MIL-88B(Fe)的生物炭，记为BC@MIL-88B(Fe)）实现了对四环素（TC）和土霉素（OTC）分别高达821.51和931.87 mg g的超高吸附容量，该吸附剂进一步固定在三维多孔明胶（GA）基质中。所得的BCM/GA在较宽的pH范围内以及在腐殖酸干扰下均表现出优异的吸附性能。此外，它可以经受超过8个循环，甚至在不同的实际水样中保持高吸附效率。值得注意的是，BCM/GA可以在含有其他种类抗生素的多元体系中以及从动态吸附体系中选择性地去除四环素类。最重要的是，X射线光电子能谱、二维傅里叶变换红外相关光谱（2D-FTIR-COS）和密度泛函理论技术的结果表明：（1）对于TC吸附，在pH < 4.0时络合作用的贡献为25%-45%，而孔填充和氢键作用占总吸附量的39%-72%。在4.0 < pH < 10.0时，络合作用的贡献增加到60%-82%，而静电吸引和π-π相互作用分别为4%-13%和2%-10%。（2）对于OTC吸附，在3.0 < pH < 10.0时络合作用占主导，占总吸附量的55%-86%，静电吸引和π-π相互作用分别占3%-10%和3%-15%。（3）在pH > 10.0时，孔填充主导TC和OTC吸附。最后，还通过2D-FTIR-COS探究了主要吸附机制的反应顺序。这项工作解决了MOF粉末可回收性差的问题，并为MOFs去除抗生素提供了机理见解。
