One-Pot Synthesis of Mesoporous Anatase-TiO2 (B) Mixed-Phase Nanowires Decorated with Sulfur and Fe2 O3 Nanoparticles for Visible-Light Photochemical Oxidation

Development of iron-based biochar for enhancing nitrate adsorption: Effects of specific surface area, electrostatic force, and functional groups

The problem of nitrate contamination in water has attracted widespread attention. Original biochar has a poor adsorption capacity for nitrate adsorption. Iron impregnation and acid protonation (base deprotonation) are common modification methods for biochar. In order to develop iron-mediated biochar containing multi-functional groups for enhancing nitrate adsorption, Fe-BC@H and Fe-BC@OH were prepared using a two-stage development process, including an iron-based carbon pyrolysis followed by acid protonation (or base deprotonation). The pseudo-second-order kinetic and Langmuir models can well describe the adsorption process which is a physicochemical complex monolayer adsorption. The data proved that Fe-BC@H (9.35 mg/g NO₃^--N) had a stronger adsorption capacity than Fe-BC@OH (2.95 mg/g NO₃^--N). Surface morphologies, functional groups, and mineral compositions of Fe-BC@H and Fe-BC@OH were analyzed through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Characterization results showed that acid protonation can further improve the specific surface area (SSA), pore volume, and Zeta potential of Fe-based biochar, providing more adsorption sites for nitrate and enhancing the electrostatic force between nitrate and biochar. However, these effects were suppressed through base deprotonation. In addition, acid protonation can significantly increase the type and number of functional groups of biochar to enhance the chemisorption of nitrate. Such results suggested that the acid protonation can further improve the adsorption capacity of Fe-based biochar for nitrate, while base deprotonation had an inhibitory effect on that of Fe-based biochar. Overall, this study reveals that specific surface area, electrostatic force, and functional groups are crucial effects of the nitrate adsorption on acid/base modified biochar.

Advanced membrane bioreactors systems: New materials and hybrid process design

Membrane bioreactor (MBR) is deemed as one of the most powerful technologies for efficient municipal and industrial wastewater treatment around the world. However, low microbial activity of activated sludge and serious membrane fouling still remain big challenges in worldwide application of MBR technology. Nowadays, more and more progresses on the research and development of advanced MBR with new materials and hybrid process are just on the way. In this paper, an overview on the perspective of high efficient strains applied into MBR for biological activity enhancement and fouling reduction is provided first. Secondly, as emerging fouling control strategy, design and fabrication of novel anti-fouling composited membranes are comprehensively highlighted. Meanwhile, hybrid MBR systems integrated with some novel dynamic membrane modules and/or with other technologies like advanced oxidation processes (AOPs) are introduced and compared. Finally, the challenges and opportunities of advanced MBRs combined with bioenergy production in wastewater treatment are discussed.

Preparation of immobilized coating Fenton-like catalyst for high efficient degradation of phenol

In this study, solid acid amorphous Fe₃O₄/SiO₂ ceramic coating decorated with sulfur on Q235 carbon steel as Fenton-like catalyst for phenol degradation was successfully prepared by plasma electrolytic oxidation (PEO) in silicate electrolyte containing Na₂S₂O₈ as sulfur source. The surface morphology and phase composition were characterized by SEM, EDS, XRD and XPS analyses. NH₃-TPD was used to evaluate surface acidity of PEO coating. The results indicated that sulfur decorated amorphous Fe₃O₄/SiO₂ ceramic coatings with porous structure and higher acid strength had the similar pore size and the surface became more and more uneven with the increase of Na₂S₂O₈ in the silicate electrolyte. The Fenton-like catalytic activity of sulfur decorated PEO coatings was also evaluated. In contrast to negligible catalytic activity of sulfur undecorated PEO coating, catalytic activity of sulfur decorated PEO coating was excellent and PEO coating prepared with 3.0 g Na₂S₂O₈ had the highest catalytic activity which could degrade 99% of phenol within 8 min under circumneutral pH. The outstanding performance of sulfur decorated PEO coating was attributed to strong acidic microenvironment and more Fe²⁺ on the surface. The strong acid sites played a key factor in determining catalytic activity of catalyst. In conclusion, rapid phenol removal under circumneutral pH and easier separation endowed it potential application in wastewater treatment. In addition, this strategy of preparing immobilized solid acid coating could provide guidance for designing Fenton-like catalyst with excellent catalytic activity and easier separation.