Boron nitride quantum dots decorated MIL-100(Fe) for boosting the photo-generated charge separation in photocatalytic refractory antibiotics removal

Boron nitride quantum dots supported hollow NH2-MIL-125 drive photo-Fenton-PMS system for photocatalytic tetracycline degradation: Contribution of tannic acid etching

NH2-MIL-125(Ti) materials had great potential for photocatalytic applications but had low activity due to exciton effect and narrow absorption range of visible light. The surface oxygen-containing negative functional groups of boron nitride quantum dots (BNQDs) could overcome these defects, but due to the low load capacity, a higher specific surface area of the substrate was usually required. In this paper, a hollow Ti-MOF material was developed by etching technology. The hollow structure formed by tannic acid etching broadened the absorption range of visable light and provided more alternative surfaces for loading BNQDs. The 85.2% of high tetracycline (TC) removal efficiency for the best sample (BNQDs-5@20-Ti-MOF + PMS) was obtained, which was about 56.8 and 1.9 times of the 20-Ti-MOF and BNQDs-5@20-Ti-MOF, respectively. BNQDs-5@20-Ti-MOF + PMS system showed a great TC degradation efficiency in a wide pH range (pH = 5-9). In addition, reaction temperature and the inorganic ions did not show significant inhibition effect for TC removal. Both free radical and non-free radical pathways were involved in the TC degration by BNQDs-5@20-Ti-MOF + PMS system, among which O2•- and 1O2 played the key roles. Interestingly, multiple 1O2 production paths contributed to the high efficiency and stability of BNQDs-5@20-Ti-MOF + PMS system. This study revealed a reasonable combination of Ti-MOF and BNQDs, which provided a new efficient photocatalyst for environmental remediation.

A review on development and modification strategies of MOFs Z-scheme heterojunction for photocatalytic wastewater treatment, water splitting, and DFT calculations

Increasing water pollution and decreasing energy reserves have emerged as growing concerns for the environment. These pollution are due to the dangerous effects of numerous pollutants on humans and aquatic organisms, such as hydrocarbons, biphenyls, pesticides, dyes, pharmaceuticals, and metal ions. On the other hand, the need for a clean environment, finding alternatives to fossil and renewable fuels is very important. Hydrogen (H2) is regarded as a viable and promising substitute for fossil fuels, and a range of methodologies have been devised to generate this particular source of energy. Metal-organic frameworks (MOFs) are a new generation of nanoporous coordination polymers whose crystal structure is composed of the juxtaposition of organic and inorganic constituent units. Due to their flexible nature, regular structure, and high surface area, these materials have attracted much attention for removing various pollutants from water and wastewater, and water splitting. MOFs Z-scheme heterojunctions have been identified as an economical and eco-friendly method for eliminating pollutants from wastewater systems, and producing H2. Their low-cost synthesis and unique properties increase their application in various energy and environment fields. The heterojunctions possess diverse properties, such as exceptional surface area, making them ideal for degradation and separation. The development and formulation of Z-scheme heterojunctions photocatalytic systems using MOFs, which possess stable and potent redox capability, have emerged as a successful approach for addressing environmental pollution and energy shortages in recent times. Through the utilization of the benefits offered by MOFs Z-scheme heterojunctions photocatalysts, such as efficient separation and migration of charge carriers, extensive spectrum of light absorption, among other advantages, notable enhancements can be attained. This review encompasses the synthesis techniques, structure, and properties of MOFs Z-scheme heterojunctions, and their extensive use in treating various wastewaters, including dyes, pharmaceuticals, and heavy metals, and water splitting. Also, it provides an overview of the mechanisms, pathways, and various theoretical and practical aspects for MOFs Z-scheme heterojunctions. Finally, it thoroughly assesses existing challenges and suggests further research on the promising applications of MOFs Z-scheme in industrial-scale wastewater treatment.

Impact of Polythiophene ((C4H4S)n; n = 3, 5, 7, 9) Units on the Adsorption, Reactivity, and Photodegradation Mechanism of Tetracycline by Ti-Doped Graphene/Boron Nitride (Ti@GP_BN) Nanocomposite Materials: Insights from Computational Study

This study addresses the formidable persistence of tetracycline (TC) in the environment and its adverse impact on soil, water, and microbial ecosystems. To combat this issue, an innovative approach by varying polythiophene ((C4H4S)n; n = 3, 5, 7, 9) units and the subsequent interaction with Ti-doped graphene/boron nitride (Ti@GP_BN) nanocomposites was applied as catalysts for investigating the molecular structure, adsorption, excitation analysis, and photodegradation mechanism of tetracycline within the framework of density functional theory (DFT) at the B3LYP-gd3bj/def2svp method. This study reveals a compelling correlation between the adsorption potential of the nanocomposites and their corresponding excitation behaviors, particularly notable in the fifth and seventh units of the polythiophene configuration. These units exhibit distinct excitation patterns, characterized by energy levels of 1.3406 and 924.81 nm wavelengths for the fifth unit and 1.3391 and 925.88 nm wavelengths for the seventh unit. Through exploring deeper, the examination of the exciton binding energy emerges as a pivotal factor, bolstering the outcomes derived from both UV-vis transition analysis and adsorption exploration. Notably, the calculated exciton binding energies of 0.120 and 0.103 eV for polythiophene units containing 5 and 7 segments, respectively, provide compelling confirmation of our findings. This convergence of data reinforces the integrity of our earlier analyses, enhancing our understanding of the intricate electronic and energetic interplay within these intricate systems. This study sheds light on the promising potential of the polythiophene/Ti-doped graphene/boron nitride nanocomposite as an efficient candidate for TC photodegradation, contributing to the advancement of sustainable environmental remediation strategies. This study was conducted theoretically; hence, experimental studies are needed to authenticate the use of the studied nanocomposites for degrading TC.

Recent perspective of antibiotics remediation: A review of the principles, mechanisms, and chemistry controlling remediation from aqueous media

Antibiotic pollution is an ever-growing concern that affects the growth of plants and the well-being of animals and humans. Research on antibiotics remediation from aqueous media has grown over the years and previous reviews have highlighted recent advances in antibiotics remediation technologies, perspectives on antibiotics ecotoxicity, and the development of antibiotic-resistant genes. Nevertheless, the relationship between antibiotics solution chemistry, remediation technology, and the interactions between antibiotics and adsorbents at the molecular level is still elusive. Thus, this review summarizes recent literature on antibiotics remediation from aqueous media and the adsorption perspective. The review discusses the principles, mechanisms, and solution chemistry of antibiotics and how they affect remediation and the type of adsorbents used for antibiotic adsorption processes. The literature analysis revealed that: (i) Although antibiotics extraction and detection techniques have evolved from single-substrate-oriented to multi-substrates-oriented detection technologies, antibiotics pollution remains a great danger to the environment due to its trace level; (ii) Some of the most effective antibiotic remediation technologies are still at the laboratory scale. Thus, upscaling these technologies to field level will require funding, which brings in more constraints and doubts patterning to whether the technology will achieve the same performance as in the laboratory; and (iii) Adsorption technologies remain the most affordable for antibiotic remediation. However, the recent trends show more focus on developing high-end adsorbents which are expensive and sometimes less efficient compared to existing adsorbents. Thus, more research needs to focus on developing cheaper and less complex adsorbents from readily available raw materials. This review will be beneficial to stakeholders, researchers, and public health professionals for the efficient management of antibiotics for a refined decision.

Electrospun composite nanofibers as novel high-performance and visible-light photocatalysts for removal of environmental pollutants: A review

Environmental pollution caused by industries and human manipulations is coming a serious global challenge. On the other hand, the world is facing an energy crisis caused by population growth. Designing solar-driven photocatalysts which are inspired by the photosynthesis of plant leaves is a fantastic solution to use solar energy as green, available, and unlimited energy containing ∼50% visible light for the removal of environmental pollutants. The polymeric and non-polymeric-based electrospun composite nanofibers (NFs) are as innovative photocatalytic candidates which increase photocatalytic activity and transition from UV light to visible light and overcome the aggregation, photocorrosion, toxicity, and hard recycling and separation of the nanosized powder form of photocatalysts. The composite NFs are fabricated easily by either embedding the photocatalytic agents into the NFs during electrospinning or via their decorating on the surface of NFs post-electrospinning. Polyacrylonitrile-based, tungsten trioxide-based, zinc oxide-based, and titanium dioxide-based composite NFs were revealed as the most reported composite NFs. All the lately investigated electrospun composite NFs indicated long-term stability, high photocatalytic efficiency (∼> 80%) within a short time of light radiation (10-430 min), and high stability after several cycles of use. They were applied in various applications including degradation of dyes/antibiotics, water splitting, wastewater treatment, antibacterial usage, etc. The photogenerated species especially holes, O2∙-, and .OH were mostly responsible for the photocatalytic mechanism and pathway. The electrospun composite NFs have the potential to use in large-scale productions in condition that their thickness and recycling conditions are optimized, and their toxicity and detaching are resolved.

2D/1D BiOI/g-C3N4 nanotubes heterostructure for photoelectrochemical overall water splitting

To boost the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances, the BiOI/graphitic carbon nitride nanotubes (g-C₃N₄ nanotubes) heterojunction was synthesized herein through the hydrothermal method. BiOI in-situ grew on the surface of g-C₃N₄ nanotubes derived from melamine. The rapid recombination between photoexcited electrons and holes of pristine semiconductors was prevented via building the stable heterojunction. The SEM results indicated that the BiOI was wrapped around the surface of g-C₃N₄ nanotubes, resulting in an optimized electronic transmission pathway. Much lower charge transfer resistance at the p-n heterojunction was demonstrated compared with pristine BiOI according to the EIS results, thus leading to the faster surface reaction rates. Moreover, the composite exhibited both outstanding OER and HER activities under illuminated conditions. This study may shed light upon establishing a bifunctional photoelectrocatalysis for photoelectrochemical water splitting based on stable 2D metal and 1D metal-free nanocomposite.

Construction of dual transfer channels in graphitic carbon nitride photocatalyst for high-efficiency environmental pollution remediation: Enhanced exciton dissociation and carrier migration

Graphitic carbon nitride (g-C₃N₄) is a promising candidate for photocatalysis, but exhibits moderate activity due to strongly bound excitons and sluggish charge migration. The dissociation of excitons to free electrons and holes is considered an effective strategy to enhance photocatalytic activity. Herein, a novel boron nitride quantum dots (BNQDs) modified P-doped g-C₃N₄ photocatalyst (BQPN) was successfully prepared by thermal polymerization method. Photoluminescence techniques and photoelectrochemical tests demonstrated that the introduction of P atoms and BNQDs promoted the dissociation of excitons and the migration of photogenerated carriers. Specifically, theoretical calculations revealed that P substitutions were the sites of pooled electrons, while BNQDs were the excellent photogenerated hole extractors. Accordingly, compared with g-C₃N₄, the BQPN showed improved performance in degrading four non-steroidal anti-inflammatory drugs (NSAIDs) under visible light irradiation. This work not only establishes an in-depth understanding of excitonic regulation in g-C₃N₄, but also offers a promising photocatalytic technology for environmental remediation.

Co-doped Fe-MIL-100 as an adsorbent for tetracycline removal from aqueous solution

In the study, Fe-MIL-100 was modified by adding Co²⁺ in the synthesis process; Co/Fe-MIL-100 was successfully synthesized and used to adsorb tetracycline. The addition of Co²⁺ increased the thermal stability of Fe-MIL-100 without changing the crystal structure. It was found that Co/Fe-MIL-100 exhibited satisfactory performance in tetracycline removal, the tetracycline removal efficiency reached almost 100% in the initial concentration range of 10-40 mg/L, and it still reached 82.38% under the condition of 60 mg/L tetracycline. Besides, the factors of tetracycline concentration, pH and inorganic anion on removal efficiency were explored. The coexistence of inorganic anion decreased the adsorption capacity of tetracycline due to the competitive adsorption. CO₃^2- had a more obvious inhibition effect on the adsorption efficiency of tetracycline than Cl^-. The fitting correlation coefficient of Langmuir model was higher and the kinetics better fitted by pseudo-second-order, respectively. As a result of its high removal efficiency and excellent recycling performance, it has great potential in application fields such as removing tetracycline from wastewater.