Solar photocatalytic degradation of emerging contaminants using NH2-MIL-125 grafted by heterocycles

High-efficiency removal of microcystis aeruginosa using Z-scheme AgBr/NH2-MIL-125(Ti) photocatalyst with superior visible-light absorption: Performance insights and mechanisms

Algal blooms have become a widespread concern for drinking water production, threatening ecosystems and human health. Photocatalysis, a promising advanced oxidation process (AOP) technology for wastewater treatment, is considered a potential measure for in situ remediation of algal blooms. However, conventional photocatalysts often suffer from limited visible-light response and rapid recombination of photogenerated electron-hole pairs. In this study, we prepared a Z-scheme AgBr/NH2-MIL-125(Ti) composite with excellent visible light absorption performance using co-precipitation to efficiently inactivate Microcystis aeruginosa. The degradation efficiency of AgBr/NH2-MIL-125(Ti) for chlorophyll a was 98.7 % after 180 min of visible light irradiation, significantly surpassing the degradation rate efficiency of AgBr and NH2-MIL-125(Ti) by factors of 3.20 and 36.75, respectively. Moreover, the removal rate was maintained at 91.1 % even after five times of repeated use. The experimental results indicated that superoxide radicals (•O2-) were the dominant reactive oxygen species involved. The photocatalytic reaction altered the morphology and surface charge of algal cells, inhibited their metabolism, and disrupted their photosynthetic and antioxidant systems. In conclusion, this study presents a promising material for the application of photocatalytic technology in algal bloom remediation.

Industrial waste-based adsorbents as a new trend for removal of water-borne emerging contaminants

Emerging contaminants in wastewater are one of the growing concerns because of their adverse effects on human health and ecosystems. Adsorption technology offers superior performance due to its cost-effectiveness, stability, recyclability, and reliability in maintaining environmental and health standards for toxic pollutants. Despite extensive research on the use of traditional adsorbents to remove emerging contaminants, their expensiveness, lack of selectivity, and complexity of regeneration remain some of the challenges. Industrial wastes viz. blast furnace slag, red mud, and copper slag can be used to develop efficacious adsorbents for the treatment of emerging contaminants in water. Advantages of the use of such industrial wastes include resource utilization, availability, cost-effectiveness, and waste management. Nevertheless, little is known so far about their application, removal efficacy, adsorption mechanisms, and limitations in the treatment of emerging contaminants. A holistic understanding of the application of such unique industrial waste-derived adsorbents in removing emerging contaminants from water is need of the hour to transform this technology from bench-scale to pilot and large-scale applications. This review investigates different water treatment techniques associated with industrial waste-based adsorbents derived from blast furnace slag, red mud, and copper slag. Besides, this review provides important insights into the growing trends of utilizing such novel types of adsorbents to remove emerging contaminants from water with an emphasis on removal efficacy, controlling measures, adsorption mechanisms, advantages, and limitations. The present timely review brings the current state of knowledge into a single reference which could be a strong platform for future research in understanding the latest advancements, decision making, and financial management related to the treatment of wastewater using industrial waste-based adsorbents.

A state-of-art-review on emerging contaminants: Environmental chemistry, health effect, and modern treatment methods

Pollution problems are increasingly becoming e a priority issue from both scientific and technological points of view. The dispersion and frequency of pollutants in the environment are on the rise, leading to the emergence have been increasing, including of a new class of contaminants that not only impact the environment but also pose risks to people's health. Therefore, developing new methods for identifying and quantifying these pollutants classified as emerging contaminants is imperative. These methods enable regulatory actions that effectively minimize their adverse effects to take steps to regulate and reduce their impact. On the other hand, these new contaminants represent a challenge for current technologies to be adapted to control and remove emerging contaminants and involve innovative, eco-friendly, and sustainable remediation technologies. There is a vast amount of information collected in this review on emerging pollutants, comparing the identification and quantification methods, the technologies applied for their control and remediation, and the policies and regulations necessary for their operation and application. In addition, This review will deal with different aspects of emerging contaminants, their origin, nature, detection, and treatment concerning water and wastewater.

Accelerated electron and mass transfer through constructing H2WO4/Ti3C2/g-C3N4 Z-scheme photocatalyst for environmental remediation

The catalytic efficiency of photocatalysts highly depends on electron transport and mass transfer. Herein, we designed and prepared an effective H2WO4/Ti3C2/g-C3N4 (HTC) Z-scheme heterojunction through interfacial engineering strategy. The results manifested that 97.4% of Cr(VI) (80 μM, 50 mL) could be removed by HTC heterojunction within 10 min under visible light irradiation. The reduction rate constant of Cr(VI) for H2WO4/g-C3N4 (HC) heterojunction increased by a factor of 21 after introducing the conductive Ti3C2. Moreover, 96% of tetracycline (TC, 10 mg L-1, 50 mL) could be degraded by HTC heterojunction within 30 min. The electronic conductivity and ionic diffusion coefficient of HC heterojunction increased by a factor of 64 and 1064 after adding Ti3C2, respectively. This result indicated that the introduction of highly conductive Ti3C2 significantly improved the electron and mass transfer of the heterojunction. Meanwhile, the HCT heterojunction displayed favorable photocurrent, and keep excellent photostability during the long-term test. Moreover, density functional theory (DFT) calculations demonstrated that the internal electric field (IEF) from g-C3N4 to H2WO4 in HCT heterojunction promotes the combination of the photoinduced electrons in the H2WO4 conduction band (CB) with photoinduced holes in the g-C3N4 valence band (VB), thus accelerating the charge transfer in the HCT Z-scheme heterojunction. The antibacterial efficiency of HTC heterojunction against E. coli and S. aureus could reach up to 98.4% and 99.7%, respectively. The degradation intermediates and the potential degradation mechanism of TC were analyzed and proposed based on the results of HPLC-MS analysis. Moreover, the toxicity of TC and degradation intermediates were estimated by Toxicity Estimation Software (T.E.S.T.) based on quantitative structure-activity relationship (QSAR). This work provided a valuable guideline for designing the effective MXene-based Z-scheme heterojunction for environmental remediation.

Design and Synthesis of NTU-9/C3N4 Photocatalysts: Effects of NTU-9 Content and Composite Preparation Method

Hybrid materials based on graphitic carbon nitride (g-C₃N₄) and NTU-9 metal-organic frameworks (MOF) were designed and prepared via solvothermal synthesis and calcination in air. The as-prepared photocatalysts were subsequently characterized using Brunauer-Emmett-Teller (BET) analysis, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) emission spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The obtained NTU-9/C₃N₄ composites showed a greatly improved photocatalytic performance for the degradation of toluene in the gas phase under LED visible-light irradiation (λ_max = 415 nm). The physicochemical properties and photocatalytic activities of the obtained NTU-9/C₃N₄ materials were tuned by varying the NTU-9 content (5-15 wt%) and preparation method of the composite materials. For composites prepared by calcination, the photocatalytic activity increased with decreasing NTU-9 content as a result of the formation of TiO₂ from the MOFs. The best photocatalytic performance (65% of toluene was photodegraded after 60 min) was achieved by the NTU-9/C₃N₄ sample prepared via the solvothermal method and containing 15 wt% MOF, which can be attributed to the appropriate amount and stable combination of composite components, efficient charge separation, and enhanced visible-light absorption ability. The photocatalytic mechanisms of the prepared hybrid materials depending on the preparation method are also discussed.