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磁性氮掺杂杉木屑生物炭活化过一硫酸盐降解左氧氟沙星

Preparation of magnetic nitrogen-doped fir sawdust biochar to activate peroxymonosulfate for Levofloxacin degradation

    摘要
  • 摘要: 广西大量的废弃杉木屑是放错位置的宝贵资源。为达到“以废治废”目的，本文以废弃杉木屑为原料制备合成了具有磁回收能力的生物炭复合材料，并研究其活化过一硫酸盐(Peroxymonosulfate，PMS)降解左氧氟沙星(Levofloxacin，LEV)抗生素的性能。通过对杉木屑生物炭(Fir sawdust biochar， BC)进行氮掺杂、Fe3O4负载制备出具有高效PMS活化能力和优异磁分离性能的磁性氮掺杂杉木屑生物炭(Magnetic nitrogen doped fir sawdust biochar， MNC)。相比BC，MNC的石墨化程度提高，缺陷活性位点增多，比表面积也得到显著改善，且具备超顺磁性和大的磁饱和强度，饱和磁化值达到10.45 emu·g−1；主要考察了PMS浓度、MNC投加量、溶液初始pH、无机阴离子与腐殖酸对MNC降解LEV的影响。研究表明：相较于BC、磁性生物炭(Magnetic fir sawdust biochar，MC)和氮掺杂生物炭(Nitrogen doped fir sawdust biochar，NC)，MNC活化PMS降解LEV的效率显著提升。当MNC投加量为1.0 g/L，PMS浓度为0.3 mmol/L，初始pH为7，LEV浓度为10 mg/L的条件下，LEV去除率在30 min达到84%；同等条件下，对双酚A(Bisphenol A，BPA)、罗丹明B(Rhodamine B，RhB)和四环素(Tetracycline，TC)的去除率分别为94%、98%和87%。Cl−、NO3−和腐殖酸(Humic acid，HA)对MNC活化PMS降解LEV无明显影响。淬灭实验证实，自由基途径和非自由基途径生成的O2−•与1O2主导了MNC/PMS体系对LEV的降解。此外，MNC循环使用4次后，活化PMS去除LEV的效率仍能达到75%左右。本文为废弃杉木屑高效、绿色的资源化利用提供了新策略和借鉴意义。

     

    Abstract: Guangxi's large amount of waste fir sawdust is a valuable resource in the wrong place. In order to realize cyclic utilization of fir sawdust, biochar composites with magnetic recovery capability were prepared from waste fir sawdust, and the performance of activated peroxymonosulfate (PMS) to degrade levofloxacin (LEV) antibiotics was studied in this study. Magnetic nitrogen-doped fir sawdust biochar (MNC) with high PMS activation ability and excellent magnetic separation performance was synthesized by nitrogen doping and loading Fe3O4. Several characterizations confirm that compared with fir sawdust biochar (BC), MNC has higher graphitization, more defect active sites, significantly improved specific surface area, superparamagnetism and large magnetic saturation intensity, with a saturation magnetization value of 10.45 emu·g−1. In addition, the effects of various environmental factors on the degradation of LEV by MNC are simulated. The effects of PMS concentration, MNC dosage, initial pH of solution, inorganic anions and humic acid are mainly investigated. The results shows that compares with BC, magnetic biochar (MC) and nitrogen doped biochar (NC), the efficiency of degradation of LEV by MNC activated PMS is significantly improved. Under the conditions of MNC dosage of 1.0 g/L, PMS concentration of 0.3 mmol/L, initial pH of 7, and LEV concentration of 10 mg/L, the removal rate of LEV reachs 84% in 30 minutes, and the removal rates of bisphenol A (BPA), rhodamine B (RhB), and tetracycline (TC) are 94%, 98% and 87%, respectively. Cl−, NO3− and humic acid have no obvious effect on the degradation of LEV by MNC activated PMS. The quenching experiments show the generation of O2−• and 1O2 through free radical and non-free radical pathways dominate the degradation of LEV in MNC/PMS system. In addition, after 4 cycles of MNC, the efficiency of activating PMS to remove LEV can still reach about 75%. This study provides a new strategy and reference for the efficient and green resource utilization of waste fir sawdust.

     

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