Search

• OFGs, PFRs and redox properties of BC facilitate the generation of ROS. • BC and BC-based catalysts could effectively activate H 2 O 2 and persulfate. • BC-based photocatalysts could effectively degrade pollutants. • BC-based catalysts could effectively degrade pollutants in sonocatalytic systems. • BC-based catalysts may be a good alternative for the degradation of pollutants. Biochar (BC) is one of the most remarkable materials for environmental remediation. An increasing number of researchers have attempted to utilize BC as a catalyst to generate reactive oxygen species (ROS) and sulfate radicals. This work focuses on the development and progress of BC-based catalysts in different systems, including redox systems, Fenton-like systems, sonocatalytic systems and photocatalytic systems. Most importantly, the catalytic performance and mechanism of different types of BC-based catalysts are thoroughly investigated. Furthermore, the applications of BC-based catalysts in wastewater, sediments, soil and gas are presented. Special attention is paid to the factors involved in the generation of ROS and sulfate radicals, such as oxygen-containing functional groups (OFGs), persistent free radicals (PFRs) and redox properties. The generation processes of ROS and sulfate radicals are presented in detail. And the removal pathways of three mechanisms are elaborated. Furthermore, research in this field is still at an early stage, and many improvements are required before the technology can be efficiently scaled up and put into practice. This review enriches the knowledge about the generation processes of ROS and sulfate radicals by BC-based catalysts and improves the understanding of the catalytic performance and catalytic mechanism of BC-based catalysts for pollutants. [ABSTRACT FROM AUTHOR]

Defect WO 3 -carbon hybrid nanosheets (D-WO 3 @C), synthesized by a facile hydrothermal method, is utilized as an effective visible-light driven photocatalyst for sustainable inactivation of bacteria . Detailed characterization through SEM-EDS, XRD, FT-IR, HRTEM, and XPS confirmed the formation of the nanohybrids. As a result, the as-synthesized D-WO 3 @C exhibited the best sterilization efficiency among all of the WO 3 photocatalysts, and 7 log inactivation of E. coli or S. aureus was obtained after treating samples for 45 min with 1000 μg/mL D-WO 3 @C. It was found that D-WO 3 @C exhibited enhanced visible-light-driven photocatalytic sterilization in killing bacteria compared with D-WO 3 and P-WO 3 . The results show that the oxygen vacancies and carbon matrix were able to promote photocatalytic performance by triggering a faster interfacial transfer and a higher efficient separation of electron-hole pairs, which most likely is the reason behind the improved bactericidal effect. Furthermore, fluorescent-based cell viability/death tests and SEM technology were employed to demonstrate the lethal effect as well as the integrity of bacterial membranes during photocatalytic process. Photoelectrochemical techniques and UV–visible diffuse reflectance revealed the efficient separation of electron-hole pairs between D-WO 3 and carbon matrix. More importantly, after being tested in four cycles, D-WO 3 @C showed good photocatalytic performance due to its chemical stability. The excellent properties associated with the novel D-WO 3 /C indicated that they could be considered as a promising light-visible driven photocatalyst to remove, in practice, microbial contamination of water. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel AgVO 3 /BiO 2-X catalyst can be cheaply and easily fabricated. • AgVO 3 /BiO 2-X is an efficient full solar spectrum photocatalyst. • DFT calculations reveals the mechanism of improved photocatalytic disinfection. • Biocompatibility experiments showed that our composites are safe materials. Photocatalytic disinfection has been regarded as a promising strategy in terms of significantly reducing microbial contamination, in which the activity of photocatalyst mainly depends on UV or visible light, however the effect of full spectrum solar light for photocatalytic disinfection has been rarely considered. Herein, we report a UV-Visible-NIR responsive photocatalyst based on vanadate quantum dots (AgVO 3 QDs) interspersed on vacancy-rich BiO 2-X (AgVO 3 /BiO 2-X) and achieve highly efficient photocatalytic disinfection for Methicillin-resistant Staphylococcus aureus (MRSA). With our approach, we achieved a 7-log inactivation of bacterial concentration within 30 min, with only a small amount of material (200 μg mL−1) under UV, visible and near-infrared light. The maximum absorption edge of AgVO 3 /BiO 2-X red-shifts from 880 nm to 930 nm, which can be attributed to the inner defective structure and formation of heterostructures, resulting in abundant production of reactive oxygen species (ROS) for bacterial inactivation. DFT calculations confirm the intimate interface contact between BiO 2-X and AgVO 3 , which benefit to the up-conversion photoluminescence properties of AgVO 3 QDs and fast interfacial electron transport through the electron tunneling mechanism. In vitro results illustrated that ROS can severely damage the cell wall of bacteria and inhibit its virulence factors, which eventually leading to the death of MRSA. Notably, assessment of wound infection showed that the material was very effective for promoting cell proliferation and differentiation, by phosphorylation of protein kinase B (Akt) signalling pathway in bacterial infection, which shows great potential as a safe, low-cost and efficient multimodal heterostructured photocatalyst in eliminating the microbial contaminated water. [ABSTRACT FROM AUTHOR]

• A binary composite MoS 2 /TiO 2 NTAs was synthesized for photocatalytic sterilization. • The water disinfection efficiency of MoS 2 /TiO 2 NTAs was up to 98.5%. • The water disinfection efficiency still reached 92.1% after 3 times recycling. • The mechanism is the damage of bacterial by O 2 – produced by photoexcitation. Despite the development of advanced photocatalysts, the practical application of photocatalytic water disinfection is still under restrictions due to the low reusability of powder photocatalysts. In this paper, we synthesized the binary composite heterojunction photocatalyst MoS 2 /TiO 2 nanotube arrays (MoS 2 /TiO 2 NTAs), using anodic oxidation method and hydrothermal method. The water disinfection efficiency of MoS 2 /TiO 2 NTAs under visible light irradiation against pathogenic bacteria was up to 98.5% and still reached 92.1% after 3 times recovering and recycling. The mechanism was proven to be the seriously damage of bacterial cell membrane caused by the ROS produced from MoS 2 /TiO 2 NTAs photocatalyst under light irradiation. In addition, we analyzed the water sample changes after material recovery by ICP-MS, and found that there is no MoS 2 nanosheet falling off. This result supported the recyclable effect of MoS 2 /TiO 2 NTAs and avoided the nanoparticles remaining in the water as much as possible. Therefore, MoS 2 /TiO 2 NTAs composites have great application prospects in water disinfection due to their excellent photocatalytic disinfection effect, recyclability and reusability. [ABSTRACT FROM AUTHOR]