Abstract
In order to solve the problem that the traditional biochar(BC) has insufficient removal ability of enrofloxacin and TiO2 is difficult to recycle. In this study, TiO2-modified biochar composites were prepared by impregnation method. Through characterization analysis, The BET specific surface area results indicated that after loading TiO2, the specific surface area of TiO2-biochar(Ti-BC), TiO2-ironized biochar(Ti-FBC) and TiO2-alkaline biochar(Ti-KBC) increased by 4.34, 10.43 and 11.52 times, respectively. The analysis results of SEM, EDS, FT-IR, XRD and XPS showed that TiO2 was supported on biochar in the anatase state. The UV-vis DRS measurement showed that the band width of Ti-KBC was the smallest and the best catalytic activity. Under 15 W UV lamp (254 nm) irradiation, the photocatalytic degradation process of enrofloxacin by different biochar accords with the first-order kinetic equation. Ti-KBC showed best degradation effect under different initial concentrations of enrofloxacin. When the pH of the solution was 5.0 and the dosage of Ti-KBC was at 2.5 g·L−1, the enrofloxacin degradation rate of 100 mg·L−1 reached 85.25%. The quenching test confirmed that the active substance O2•— played a major role in the photocatalytic degradation process. After five cycles of the test, the degradation rate of Ti-KBC for enrofloxacin was 77.14%, which was still better than that of BC, Ti-BC and Ti-FBC.
Highlights
Enrofloxacin is the third-generation fluoroquinolone antibiotic which was synthesized in 1987 and is widely used in livestock and aquaculture as antibacterial drugs, because of its highly efficient against mycoplasma[1]
The result from BET specific surface area measurement showed that the specific surface areas of the biochar Ti-BC, Ti-FBC and Ti-KBC were 15.24, 36.65 and 40.46 m2·g−1, which increased by 4.34, 10.43 and 11.52 times compared with BC, respectively
The micropore volume of Ti-FBC and Ti-KBC accounted for 66.47% and 74.44% of the total pore volume, respectively
Summary
Enrofloxacin is the third-generation fluoroquinolone antibiotic which was synthesized in 1987 and is widely used in livestock and aquaculture as antibacterial drugs, because of its highly efficient against mycoplasma[1]. Biochar is a kind of solid matter which is formed by pyrolysis of biochar raw materials such as corn stover and wood chips under oxygen-limited conditions, and has strong adsorption capacity for pollutants[5]. Compared with traditional activated carbon, biochar has limited adsorption capacity for enrofloxacin in the environment. In order to enhance the adsorption capacity of biochar, the biochar is usually modified by physical and chemical methods such as acid-base and metal solution impregnation[9,10]. Du et al.[13] carried out TiO2 on carbon nanotubes by sol-gel method and founded that the degradation rate of methylene blue by TiO2 loaded with 2% carbon nanotubes was enhanced to 90.6%. Modified activated carbon fiber (ACF) with HNO3 and synthesized a TiO2/ACF composite, the degradation efficiency of the composite to methylene blue reached 99.99% after 30 minutes of reaction. Through the structural characterization of the composite and the photocatalytic degradation test, the degradation mechanism of enrofloxacin was clarified
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