Catalytic ozonation of nitroimidazole antibiotics using nano-magnesium hydroxide as heavy-metals free catalyst

Abstract

In this study, nano-magnesium hydroxide (nano-Mg(OH) 2) was prepared and first applied for the catalytic ozonation of the widely used nitroimidazole antibiotics. Most of nitroimidazole antibiotics were rapidly removed within 10 min. The removal rate constant of metronidazole in the catalytic ozonation treatment was four times higher than that without catalyst. Persistent high catalytic activity of nano-Mg(OH) 2 maintained after three runs. The severe inhibition of hydroxyl radical scavenger (TBA) on the catalytic ozonation suggested that hydroxyl radical reaction served as the predominant process. The removal of nitroimidazole antibiotics followed a pseudo-first order kinetic model. Increase in the dosage of catalyst and reaction temperature within certain range could enhance the degradation of metronidazole, tinidazole, and dimetridazole while increase in the initial concentration of nitroimidazole antibiotics led to the decrease in the removal efficiency. All anions (Cl-, HCO 3-, and SO 4 2-) and cations (Ca 2+ and Mg 2+) had negative influence on the removal efficiency of nitroimidazole antibiotics. Due to the unique features such as low cost and heavy-metals free, high efficiency and persistent high catalytic activity of the nano-Mg(OH) 2 in the catalytic ozonation of nitroimidazole antibiotics demonstrated that nano-Mg(OH) 2 is a promising environment-friendly ozonation catalyst in terms of antibiotic removal.

Enhanced ozonation of antibiotics using magnetic Mg(OH)2 nanoparticles made through magnesium recovery from discarded bischofite

“…The FTIR spectrum of Mg(OH) 2 indicated that the sharp and intense peak at 3699 cm À1 was attributed to the O-H stretching vibration in the crystal structure while the peak at 3429 cm À1 was assigned to the stretching vibration of the eOH group from water molecules (physical adsorption molecules water) and the weak peak at about 440 cm À1 was attributed to Mg-O stretching vibration in Mg(OH) 2 crystals. The FTIR spectra of Mg(OH) 2 were well consistent with those previously reported (Sun et al, 2019). The FTIR spectrum of Fe 3 O 4 indicated that the absorption peak at 3429 cm À1 was assigned to stretching modes of O-H between molecules and 581 cm À1 corresponding to stretching and bending modes of Fe-O-Fe in Fe 3 O 4 (Huang et al, 2017).…”

“…The catalytic ozonation process utilizes catalysts to improve the ozone decomposition, enhance the generation of hydroxyl radicals, and has high oxidation efficiency and simple operation to overcome some disadvantages of ozonation (Bai et al, 2016;Huang et al, 2012;Mashayekh-Salehi et al, 2017;Shokri et al, 2016;Sun et al, 2018Sun et al, , 2019. Various catalysts including carbon-based nanomaterials (Bai et al, 2016;Yuan et al, 2018), porous materials (Huang et al, 2012;Ikhlaq et al, 2014), metal oxides (Khataee et al, 2017;Li et al, 2015;Mashayekh-Salehi et al, 2017;Yuan et al, 2013), hydroxides (Sun et al, 2019), and some emerging materials such as covalent organic framework (COF) (Wang et al, 2019a), bismuch oxyhalide (BIOX) (Wang et al, 2019b) and biomimetic material (Yi et al, 2019) have been used for the catalytic ozonation process. Among these materials, the magnesium hydroxide (Mg(OH) 2 ) is considered to be a promising ozonation catalyst because of its highly efficient activity, heavy-metals free, environmental friendliness, and low toxicity (Sun et al, 2019).…”

“…Various catalysts including carbon-based nanomaterials (Bai et al, 2016;Yuan et al, 2018), porous materials (Huang et al, 2012;Ikhlaq et al, 2014), metal oxides (Khataee et al, 2017;Li et al, 2015;Mashayekh-Salehi et al, 2017;Yuan et al, 2013), hydroxides (Sun et al, 2019), and some emerging materials such as covalent organic framework (COF) (Wang et al, 2019a), bismuch oxyhalide (BIOX) (Wang et al, 2019b) and biomimetic material (Yi et al, 2019) have been used for the catalytic ozonation process. Among these materials, the magnesium hydroxide (Mg(OH) 2 ) is considered to be a promising ozonation catalyst because of its highly efficient activity, heavy-metals free, environmental friendliness, and low toxicity (Sun et al, 2019). However, effective separation of nano-Mg(OH) 2 from water during the production process or recovery for reuse is still a challenge.…”

“…Moreover, some wastes are used as raw materials to reduce the cost of catalyst preparation. Large quantities of natural bischofite from the salt industry are often discarded due to limited reutilizing techniques, leading to the waste of valuable magnesium resources (Sun et al, 2019), which might provide raw materials for the synthesis of Mg(OH) 2 materials. Few studies on the synthesis and using this kind of core-shell Fe 3 O 4 @Mg(OH) 2 composite as ozonation catalyst are reported.…”

Synthesis of magnetic core-shell Fe3O4@SiO2@Mg(OH)2 composite using waste bischofite and its catalytic performance for ozonation of antibiotics

“…Among different AOPs, catalytic ozonation is a promising approach for removing the recalcitrant pollutants due to rapid reaction rate and gentle reaction conditions [3]. More attention has been recently paid for developing different catalysts since they are critical for catalytic ozonation [3,4,20]. Magnetic Mg(OH) 2 (Fe 3 O 4 @Mg (OH) 2 ) prepared by bischofite is proved as an effective catalyst with easy separation feature for ozonation of antibiotics [3].…”