Enhanced degradation and mineralization of estriol over ZrO2/OMS-2 nanocomposite: Kinetics, pathway and mechanism

Using waste to treat waste: facile synthesis of hollow carbon nanospheres from lignin for water decontamination

Lignin, the most abundant natural material, is considered as a low-value commercial biomass waste from paper mills and wineries. In an effort to turn biomass waste into a highly valuable material, herein, a new-type of hollow carbon nanospheres (HCNs) is designed and synthesized by pyrolysis of biomass dealkali lignin, as an efficient nanocatalyst for the elimination of antibiotics in complex water matrices. Detailed characterization shows that HCNs possess a hollow nanosphere structure, with abundant graphitic C/N and surface N and O-containing functional groups favorable for peroxydisulfate (PDS) activation. Among them, HCN-500 provides the maximum degradation rate (95.0%) and mineralization efficiency (74.4%) surpassing those of most metal-based advanced oxidation processes (AOPs) in the elimination of oxytetracycline (OTC). Density functional theory (DFT) calculations and high-resolution mass spectroscopy (HR-MS) were employed to reveal the possible degradation pathway of OTC elimination. In addition, the HCN-500/PDS system is also successfully applied to real antibiotics removal in complex water matrices (e.g. river water and tap water), with excellent catalytic performances.

Photocatalytic Degradation and Mineralization of Estriol (E3) Hormone Using Boron-Doped TiO2 Catalyst

In this research work, boron-doped titanium oxide (B-TiO2) was prepared by the sol-gel method to investigate its behavior in the degradation of the recalcitrant hormone estriol (E3). The doped photocatalyst was synthesized at different boron/titania ratios of 2, 3, and 5 wt.% of boron with respect to the TiO2 content. The obtained materials were characterized by UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The textural properties, specific surface area, and porosity were obtained from N2 adsorption–desorption isotherms by BET and BJH methods, respectively. The photocatalytic performance of each synthesized catalyst was evaluated on the degradation of an aqueous solution (10 mg/L) of estriol (E3) under simulated solar radiation. The variation in the hormone concentration was determined by the HPLC technique, and the mineralization was evaluated by the quantification of total organic carbon (TOC). The obtained results indicated that the catalyst with 3 wt.% of boron incorporation exhibited the best performance on the degradation and mineralization of estriol, achieving its complete degradation at 300 kJ/m2 of accumulated energy and 71% of mineralization at 400 kJ/m2 (2 h) obtaining a non-toxic effluent.