Super facile one-step synthesis of sugarcane bagasse derived N-doped porous biochar for adsorption of ciprofloxacin.

A new N-doped biochar derived from sugarcane bagasse (NSB) was prepared by one-pot pyrolysis with sugarcane bagasse as feedstock, melamine as nitrogen source and NaHCO3 as pore-forming agent, and then NSB was used to adsorb ciprofloxacin (CIP) in water. The optimal preparation conditions of NSB were determined based on the evaluation index of adsorbability of NSB for CIP. SEM, EDS, XRD, FTIR, XPS and BET characterizations were used to analyze the physicochemical properties of the synthetic NSB. It was found that the prepared NSB had excellent pore structure, high specific surface area and more nitrogenous functional groups. Meanwhile, it was demonstrated that the synergistic interaction between melamine and NaHCO3 increased the pores of NSB and the largest surface area of NSB was 1712.19 m2/g. The CIP adsorption capacity of 212 mg/g was obtained under optimal parameters as follows: NSB amount 0.125 g/L, initial pH 6.58, adsorption temperature 30 °C, CIP initial concentration 30 mg/L and adsorption time 1 h. The isotherm and kinetics studies elucidated that the adsorption of CIP conformed both D-R model and Pseudo-second-order kinetic model. The high CIP adsorption capacity of NSB for CIP was due to the combined filling pore, π-π conjugation and hydrogen bonding. All results demonstrated that adsorption of CIP by the low-cost N-doped biochar of NSB is a reliable technology for the disposal of CIP wastewater.

Insight into catalytic activation of bisulfite for lomefloxacin degradation by simple composite of calcinated red mud.

Antibiotic was detected in many environments, and it had posed a serious threat to human health. The advanced oxidation process has been considered an effective way to treat antibiotics. In this work, using industrial waste red mud (RM) as raw material, a series of modified RM (MRM-T; T donates the calcination temperature) was obtained via a facile calcination method and applied to activate sodium bisulfite (NaHSO3) for the lomefloxacin (LOM) degradation. Among all MRM-T, MRM-700 exhibited superior catalytic activity, and approximately 89% of LOM (10 mg/L) was degraded at 30 min through the activation of NaHSO3 ([NaHSO3] = 0.5 g/L) by MRM-700 ([MRM-700] = 0.9 g/L). Moreover, the kinetic constant of LOM removal in the MRM-700/NaHSO3 system (0.082 min-1) was 16.4 times higher than that of the RM-raw/NaHSO3 system (0.005 min-1). The as-synthesized product of MRM-700 was characterized by N2 adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectra. The result indicated that the catalyst possessed excellent pore structure, high specific area, and abundant Fe3+ sites, and the lattice of Fe2O3 was doped after calcination, both of which were favorable for the activation of NaHSO3. The quenching experiment proved that •SO4- and •OH- active species were produced in MRM-700/NaHSO3 system, and •SO4- played a dominant role in LOM removal. In addition, the potential LOM degradation pathway was analyzed via UPLC-MS technology and density functional theory (DFT) calculation, and the toxicity of the treated LOM solution was tested by the culture of mung bean sprouts. This study not only provided a feasible strategy for the valuable use of RM to activate NaHSO3 but also offered a cost-effective catalyst for the efficient removal of pollutants in wastewater.