Electrochemical oxidation of carbamazepine in water using enhanced blue TiO2 nanotube arrays anode on porous titanium substrate

Antibacterial and surface properties of post-light-activated metal-free phthalocyanine-deposited TiO2 nanotube smart surfaces

The utilisation of implantable medical devices has become safer and more prevalent since the establishment of sterilisation methods and techniques a century ago. Nevertheless, device-associated infections remain a significant and growing concern, particularly in light of the continued rise in the number of medical device implantations. This underscores the imperative for the development of efficacious prevention and treatment strategies for device-associated infections, as well as further investigation into the design of innovative antibacterial surfaces for medical device applications. The motivation of this work is to investigate the post-light-activated antibacterial photosensitive surfaces fabricated on medical titanium (Ti) surfaces. Thus, in this work, metal-free phthalocyanine (H2Pc)-deposited TiO2 nanotube (TNT) array smart photosensitive surfaces were fabricated on titanium (Ti) surfaces for medical device applications. First, well-ordered nanotube surfaces were produced on titanium using an anodic oxidation (AO) process. Then, H2Pc was accumulated onto TNT surfaces using a physical vapour deposition (PVD-TE) process. H2Pc-deposited TNT surfaces were fabricated on Ti substrates by combining AO and physical vapour deposition (PVD-TE) processes in this work for the first time in the literature. H2Pc was largely coated onto TNT arrays and exhibited elemental homogeneity throughout the whole surface. The contact angle of H2Pc-deposited TNT surfaces was about 89° whereas other Ti and TNT surfaces demonstrated hydrophilic characteristics. Therefore, they exhibited remarkable hydrophobic behavior in terms of antibacterial properties. Importantly, compared to Ti and TNT surfaces, the bacterial inhibition on sunlight-activated H2Pc-deposited TNT surfaces was 94.9% for S. aureus and 97.3% for E. coli, respectively. According to these results, H2Pc-deposited TNT innovative surfaces provided superior antibacterial activity post-light-activation under sunlight due to their photosensitive character.

Electrochemical degradation of aromatic organophosphate esters: Mechanisms, toxicity changes, and ecological risk assessment

Aromatic organophosphate esters (AOPEs), including triphenyl phosphate (TPHP), tricresyl phosphate (TCP), and 2-ethylhexyl diphenyl phosphate (EHDPP), pose significant health and ecological risks. Electrochemical advanced oxidation process (EAOP) is effective in removing refractory pollutants. In this study, the degradation performance and detoxication ability of AOPEs by EAOP were investigated. Hydroxylation, oxidation, and bond cleavage products were identified as major degradation products (DPs) due to the reaction with ·OH and O₂·-. Toxicity assessments using ecological structure activity relationship (ECOSAR) model and flow cytometry (FCM) revealed the cytotoxicity and aquatic toxicity for DPs were significantly decreased. 16S rRNA gene sequencing of sediment exposure to AOPEs and DPs were applied to assess ecological toxicity, and results showed reduced bacterial richness and diversity with EHDPP and TCP, while TPHP slightly enhanced richness. AOPEs and DPs altered bacterial genera involved in carbon, nitrogen, sulfur cycling and organic compound degradation. Bacterial community assembly suggested elevated stochastic processes and reduced ecotoxicity, confirming AOPEs can be effectively detoxified by 10-min EAOP treatment. Molecular ecological network analysis indicated increased complexity and stability of bacterial communities with DPs. These findings comprehensively revealed the toxicity of AOPEs and their DPs and provided the first evidence of effective degradation and detoxification by EAOP from ecotoxicological perspective.

Integrated electrochemical-adsorption for simultaneous removal of pharmaceuticals from water: Process optimization and synergistic insights

Water contamination with pharmaceuticals has become an evident environmental challenge. Treatment processes such as electrochemical oxidation (EO) and adsorption have limitations in the simultaneous removal of pharmaceuticals from water. Therefore, this study examined the potential of coupled process (EO followed by adsorption) in binary pharmaceuticals (acetaminophen (ACM) + ciprofloxacin (CIP)) removal from water, with an emphasis on coupled process optimization. Consequently, optimized coupled process conditions including current density (22 mA/cm2), pH (5.5), EO time (40 min), adsorbent dose (0.1 g/L) and adsorption time (60 min) were obtained. Under optimal conditions, removal efficiencies of 94.6% (ACM)+92% (CIP), 94.07% (ACM)+91.15% (CIP), and > 99.8% (ACM + CIP) were recorded for 20 mg/L (ACM + CIP) removal in EO, adsorption and EO + adsorption, respectively. Further, the coupled process was employed in multiple pharmaceuticals (20 mg/L of ACM + CIP + ATN (atenolol) + AMX (amoxicillin)) removal from water and removal of > 97.56% (ACM + CIP + ATN + AMX) was achieved. Removal efficiencies of ACM (83.35%) + CIP (73.1%) + ATN (68.52%) + AMX (63.05%) and ACM (80.37%) + CIP (66.5%) + ATN (73.07%) + AMX (60.5%) were obtained in EO and adsorption, respectively. The noted lower removal efficiencies in EO and adsorption are associated with the diverse nature of the pharmaceuticals, limited adsorbent active sites, and the shared utilization of reactive oxygen species (ROS) among the pharmaceuticals in EO. The total organic carbon (TOC) removal of 40.24%, and 99% and chemical oxygen demand (COD) removal of 72.45%, and 99.6% were obtained under optimal conditions of EO, and coupled process, respectively. These findings indicate that the pharmaceuticals are only partially mineralized in EO and the subsequent adsorption effectively eliminated the remaining target pharmaceuticals, and degradation by-products from water. Additionally, integrating EO with adsorption reduced the electrical energy consumption of the EO process from 31.6 kWh/m³ to 6 kWh/m³ under optimal conditions. Overall, coupling EO with adsorption offers the utmost advantages when removing multiple pharmaceuticals from complex water matrices.

Efficient electrochemical degradation of ceftazidime by Ti3+ self-doping TiO2 nanotube-based Sb-SnO2 nanoflowers as an intermediate layer on a modified PbO2 electrode

Ceftazidime (CAZ) is an emerging organic pollutant with a long-lasting presence in the environment. Although some PbO2 materials exhibit degradation capabilities, inefficient electron transport in the substrate layer and the problem of electrode stability still limit their use. Here, an interfacial design in which TiO2 nanotube arrays generate Ti3+ self-doping oxide substrate layers and highly active 3D Sb-SnO2 nanoflowers-like interlayers was used to prepare PbO2 anodes for efficient degradation of CAZ. Interestingly, after implementing Ti3+ self-doping in the PbO2 anode base layer and introducing 3D nanoflowers-like structures, the capacity for •OH generation increased significantly. The modified electrode exhibited 5-fold greater •OH generation capacity compared to the unmodified electrode, and a 2.7-fold longer accelerated electrode lifetime. The results indicate that interfacial engineering of the base and intermediate layers of the electrodes can improve the electron transfer efficiency, promote the formation of •OH, and extend the anode lifetime of the activated CAZ system.

Electrochemically enhanced activation of Co3O4/TiO2 nanotube array anode for persulfate toward high catalytic activity, low energy consumption, and long lifespan performance

Advanced oxidation processes (AOPs) can directly degrade and mineralize organic pollutants (OPs) in water by generating reactive oxygen species with strong oxidizing ability. The development of advanced electrode materials with high catalytic performance, low energy consumption, no secondary pollution, and long lifespan has become a challenge that must be addressed in this field. A heterojunction catalyst loaded with Co3O4 on TDNAs (Co3O4/RTDNAs) was designed and constructed by a simple and efficient pyrolysis (Co3O4/TDNAs) and electrochemical reduction. Co3O4 can be uniformly distributed on the inner wall and surface of the TiO2 nanotubes, enhancing the specific surface area while forming a tight conductive interface with TiO2. This facilitates rapid transmission of electrons, thereby assisting Co3O4 in quickly activating PS to form reactive oxygen species. The Ti3+ and Ov generated in Co3O4/RTDNAs can significantly improve the electrocatalytic degradation of OPs. Also, the interface formed by Co3O4 and RTDNAs will effectively suppress Co2+ leakage, thereby reducing the risk of secondary pollution. When the reaction conditions were 1 mM PMS (PDS) and a current density of 5 mA/cm2 in the EA-PMS (PDS)/Co3O4/RTDNA system, 30 mg/L TC can achieve 83.24 % (81.89 %) removal in 120 min, with very low cobalt ion leaching, while the energy consumption was reduced significantly. Therefore, EA-PS/Co3O4/RTDNA system has strong stability and a high potential for treating the OPs in AOPs.

Surface characterization and antibacterial efficiency of well-ordered TiO2 nanotube surfaces fabricated on titanium foams

Titanium (Ti)-based implants are not compatible enough due to their bio-inert character, insufficient antibacterial capabilities and stress-shielding problem for dental and orthopaedic implant applications. Thus, this work focused to fabricate, analyze and improve antibacterial properties titanium dioxide (TiO2) nanotube array surfaces on Ti foam by anodic oxidation (AO) process. The well-ordered nanotube arrays with approximately 75 nm were successfully fabricated at 40 V for 1 h on Ti foams. Ti and O were observed as major elements on AO-coated Ti foam surfaces. In addition, the existence of TiO2 structure was proved on AO-coated foam Ti surfaces. For potential dental and orthopedic implant application, in vitro antibacterial properties were investigated versus Staphylococcus aureus and Escherichia coli. For both bacteria, antibacterial properties of TiO2 nanotube surface were greater than bare Ti foam. The bacterial inhibition versus Staphylococcus aureus and Escherichia coli of TiO2 nanotube surfaces are improved as 53.3% and 69.4% compared to bare Ti foam.

Insights into electrochemical oxidation of tris(2-butoxyethyl) phosphate (TBOEP) in aquatic media: Degradation performance, mechanisms and toxicity changes of intermediate products

Tris (2-butoxyethyl) phosphate (TBOEP) has gained significant attention due to its widespread presence and potential toxicity in the environment. In this study, the degradation of TBOEP in aquatic media was investigated using electrochemical oxidation technology. The anode Ti/SnO2-Sb/La-PbO2 demonstrated effective degradation performance, with a reaction constant (k) of 0.6927 min-1 and energy consumption of 1.24 kW h/m3 at 10 mA/cm2. CV tests, EPR tests, and quenching experiments confirmed that indirect degradation is the main degradation mechanism and ·OH radicals were the predominant reactive species, accounting for up to 93.8%. The presence of various factors, including Cl-, NO3-, HCO3- and humic acid (HA), inhibited the degradation of TBOEP, with the inhibitory effect dependent on the concentrations. A total of 13 intermediates were identified using UPLC-Orbitrap-MS/MS, and subsequent reactions led to their further degradation. Two main degradation pathways involving bond breaking, hydroxylation, and oxidation were proposed. Both Flow cytometry and the ECOSAR predictive model indicated that the intermediates exhibited lower toxic than the parent compound, resulting in a high detoxification rate of 95.9% for TBOEP. Although the impact of TBOEP on the phylum-level microbial community composition was found to be insignificant, substantial alterations in bacterial abundance were noted when examining the genus level. The dominant genus Methylotenera, representing 17.4% in the control group, decreased to 6.9% in the presence of TBOEP and slightly increased to 8.7% in the 4-min exposure group of degradation products. Electrochemical oxidation demonstrated its effectiveness for the degradation and detoxification of TBOEP in aqueous solutions, while it is essential to consider the potential impact of degradation products on sediment microbial communities.

Graphitic carbon nitride metal-free photocatalyst for the simultaneous removal of emerging pharmaceutical pollutants in wastewater

The presence of pharmaceutical pollutants in water has emerged as a significant public health concern due to their potential adverse impacts, including the development of antibiotic resistance. Consequently, advanced oxidation processes based on photocatalysis have garnered considerable attention for treating pharmaceutical contaminants in wastewater. In this study, graphitic carbon nitride (g-CN), a metal-free photocatalyst, was synthesized by the polymerization of melamine and assessed as a potential candidate for the photodegradation of acetaminophen (AP) and carbamazepine (CZ) in wastewater. Under alkaline conditions, g-CN demonstrated high removal efficiencies of 98.6% and 89.5% for AP and CZ, respectively. The relationships between degradation efficiency and catalyst dosage, initial pharmaceutical concentration, and photodegradation kinetics were investigated. Increasing the catalyst dose facilitated the removal of antibiotic contaminants, with an optimum catalyst dose of 0.1 g, achieving a photodegradation efficiency of 90.2% and 82.7% for AP and CZ, respectively. The synthesized photocatalyst removed over 98% of AP (1 mg/L) within 120 min, with a rate constant of 0.0321 min-1, 2.14 times faster than that of CZ. Quenching experiments revealed that g-CN was active under solar light and generated highly reactive oxidants such as hydroxyl (•OH) and superoxide (•O2-). The reuse test confirmed the good stability of g-CN for treating pharmaceuticals during three repeated cycles. Finally, the photodegradation mechanism and environmental impacts were discussed. This study presents a promising approach for treating and mitigating pharmaceutical contaminants in wastewater.