Adsorption-photocatalysis synergy of reusable mesoporous TiO2-ZnO for photocatalytic degradation of doxycycline antibiotic

The potentials of mesoporous TiO2-ZnO (3TiZn) were explored on photocatalytic degradation of doxycycline (DOX) antibiotic, likewise the influence of adsorption on the photocatalytic process. The 3TiZn was characterized for physical and chemical properties. Stability, reusability, kinetic and the ability of 3TiZn to degrade high concentration of pollutant under different operating conditions were investigated. Photocatalytic degradation of DOX was conducted at varied operating conditions, and the best was obtained at 1 g/L catalyst dosage, solution inherent pH (4.4) and 50 ppm of DOX. Complete degradation of 50 ppm and 100 ppm of DOX were attained within 30 and 100 min of the reaction time, respectively. The stability and reusability study of the photocatalyst proved that at the tenth (10th) cycle, the 3TiZn is as effective in the degradation of DOX as in the first cycle. This may be attributed to the fusion of the mixed oxides during calcination. The 3TiZn is mesoporous with a pore diameter of 17 nm, and this boosts it potential to degrade high concentration of DOX. It was observed that the adsorption capacity of 3TiZn enhance the photocatalytic process. It can be emphasized that 3TiZn portrayed a remarkable catalyst stability and good potentials for industrial application.

Recent progress in mineralization of emerging contaminants by advanced oxidation process: A review

Emerging contaminants are chemicals generated due to the usage of pesticide, endocrine disrupting compounds, pharmaceuticals, and personal care products and are liberated into the environment in trace quantities. The emerging contaminants eventually become a greater menace to living beings owing to their wide range and inhibitory action. To diminish these emerging contaminants from the environment, an Advanced Oxidation Process was considered as an efficient option. The Advanced Oxidation Process is an efficient method for mineralizing fractional or generous contaminants due to the generation of reactive species. The primary aim of this review paper is to provide a thorough knowledge on different Advanced Oxidation Process methods and to assess their mineralization efficacy of emerging contaminants. This study indicates the need for an integrated process for enhancing the treatment efficiency and overcoming the drawbacks of the individual Advanced Oxidation Process. Further, its application concerning technical and economic aspects is reviewed. Until now, most of the studies have been based on lab or pilot scale and do not represent the actual scenario of the emerging contaminant mineralization. Thus, the scaling up of the process was discussed, and the major challenges in large scale implementation were pointed out.

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.

Enhancement in Photocatalytic Efficiency of Commercial TiO2 Nanoparticles by Calcination: A Case of Doxycycline Removal

In this study, the pure and calcined forms of Degussa TiO2 were applied for photocatalytic removal of doxycycline - a broad-spectrum tetracycline antibiotic. The calcination of TiO2 at 500 °C enhanced the photocatalytic efficiency of the TiO2 under optimal operational conditions of 5 ppm of doxycycline, 0.25 g/L of TiO2, pH 6.5, 120 min, and room temperature. In addition, the changes in morphology, crystal structure, and optical properties of the materials before and after calcination were observed by scanning electron microscopy, X-ray diffraction, and UV-Visible spectroscopy. The reaction kinetics of the doxycycline removal was also investigated based on the Langmuir-Hinshelwood model with a correlation coefficient R2 of >80%. Results showed that the photocatalytic ability of TiO2 is stable and enhanced after being calcined at a suitable temperature of 500 °C. This opens up the potential application of TiO2 in the treatment of emerging organic pollutants in water. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Jamil SNA, Li F, Mat Azmi ID, Chiang PC, Choong TSY. Synthesis of Controlled-Release Calcium Peroxide Nanoparticles Coated with Dextran for Removal of Doxycycline from Aqueous System

Nanoscale calcium peroxide (nCP) has turned out to be one of the effective and environmentally friendly approaches for wastewater remediation purposes. The rapid hydrolysis of nCPs and burst oxygen release caused by the high surface-to-volume ratio of nCPs could surpass the appropriate demand for oxygenation and pollutant degradation in the aqueous system. Thus, coated oxidants (COs) have been prepared using polymeric materials to ensure long-term efficacy and slow-release capability. Therefore, the nCPs were first prepared using dextran as a stabilizer to prevent irreversible agglomeration by the chemical precipitation method and had an average mean size of 2.33 ± 0.81 nm. The synthesized nCPs were then coated with dextran to produce dextran-coated nCPs. Their characteristics and effectiveness in doxycycline (DOX) degradation were assessed. The characterization of nCPs and dextran-coated nCPs was performed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett and Teller analysis (BET), dynamic light scattering (DLS) and thermogravimetric analysis (TGA) techniques. This work suggests that dextran-coated nCPs are beneficial in wastewater treatment practice in terms of the long-term efficacy of DOX degradation potential.

Degradation of doxycycline antibiotics using lanthanum copper oxide microspheres under simulated sunlight

In this study, lanthanum copper oxide was synthesized under hydrothermal techniques and characterized for doxycycline degradation. The catalyst exhibited enhanced photocatalytic doxycycline degradation under visible light owing to its compatible bandgap energy (1.7 eV). The XRD data revealed high crystallinity of the material with no noticeable impurities. Three-dimensional microspheres of varying sizes (average diameter of 2.52 μm) were observed from SEM. EDX confirms the successful synthesis of La₂CuO₄. The effect of DC concentration, catalyst dosage, and initial pH on the degradation rate of DC was studied methodically. Interestingly, about 85% of doxycycline (10 mg/L) was degraded within 120 min of light-emitting diode irradiation at pH 10. Oxygen vacancies and surface defects were determined through photoluminescence spectra. The recyclability experiments suggested that the catalyst is capable of degrading DC for three consecutive runs. Radical trapping trials suggested that holes (h⁺), superoxide radicals (^●O₂^-), and hydroxyl radicals (^●OH) are involved in the photodegradation of DC. Herein, the novel approach of La₂CuO₄ synthesis and the efficient visible-light harvesting capability of as-prepared catalyst reveal the potentiality for DC degradation thereby opening a new horizon of research employing La₂CuO₄ used for various environmental applications.

Uptake of Pharmaceutical Pollutants and Their Metabolites from Soil Fertilized with Manure to Parsley Tissues

Manure is a major source of soil and plant contamination with veterinary drugs residues. The aim of this study was to evaluate the uptake of 14 veterinary pharmaceuticals by parsley from soil fertilized with manure. Pharmaceutical content was determined in roots and leaves. Liquid chromatography coupled with tandem mass spectrometry was used for targeted analysis. Screening analysis was performed to identify transformation products in the parsley tissues. A solid-liquid extraction procedure was developed combined with solid-phase extraction, providing recoveries of 61.9–97.1% for leaves and 51.7–95.6% for roots. Four analytes were detected in parsley: enrofloxacin, tylosin, sulfamethoxazole, and doxycycline. Enrofloxacin was detected at the highest concentrations (13.4–26.3 ng g⁻¹). Doxycycline accumulated mainly in the roots, tylosin in the leaves, and sulfamethoxazole was found in both tissues. 14 transformation products were identified and their distribution were determined. This study provides important data on the uptake and transformation of pharmaceuticals in plant tissues.

Environmental fate of tetracycline antibiotics: degradation pathway mechanisms, challenges, and perspectives

Tetracycline pollution is a growing global threat to aquatic and terrestrial biodiversity due to its unprecedented use in aquaculture, livestock, and human disease prevention. The influx of tetracycline may annihilate the microbial ecology structure in the environment and pose a severe threat to humans by disturbing the food chain. Although significant research data are available in the literature on various aspects of tetracycline, including detection techniques, degradation mechanisms, degradation products, and policy statements to curtail the issue, there is a scarcity of a report to compile the recent data in the literature for better analysis and comparison by the policymakers. To achieve this paucity in knowledge, the current study aims at collecting data on the available degradation strategies, mechanisms involved in biodegradable and non-biodegradable routes, the main factor affecting degradation strategies, compile novel detection techniques of tetracycline antibiotics in the environment, discuss antibiotic resistance genes and their potential role in degradation. Finally, limitations in the current bioremediation techniques and the future prospects are discussed with pointers for the decision-makers for a safer environment.

Elimination of cephalexin and doxycycline under low frequency ultrasound

Cephalexin (CPX) and doxycycline (DOX) are two of the most used antibiotics to treat bacterial infections in human medicine, veterinary practices, animal husbandry, agriculture, aquaculture, among others. Nevertheless, due to their excessive consumption and incomplete absorption during their metabolization, they have been detected in different environmental matrices and the effluents of wastewater treatment plants, which reflects that conventional water treatment methods are not enough to eliminate this type of compounds. This paper presents the main results about the removal of the antibiotics CPX and DOX under low frequency (40 kHz) ultrasonic radiation (US). The effects of operational parameters such as the solution initial pH and the applied US power were assessed considering the response surface methodology and a face centered, central composite experimental design. The results indicated that evaluated operational factors significantly affect the pollutants elimination and that US technology is able to remove them completely. In addition, in terms of mineralization, experimental results showed a reduction of the organic carbon present in the solutions and a significant increase of ions (nitrates and sulfates) concentration, suggesting that part of the organic matter was transformed into CO₂, H₂O and inorganic species. Finally, results regarding the samples toxicity indicated that ultrasonic treatment could promote a significant reduction in this parameter, and the potential negative effect associated to CPX and DOX presence in water bodies.

Biotransformation of doxycycline by Brevundimonas naejangsanensis and Sphingobacterium mizutaii strains

The fate of doxycycline (DC), a second generation tetracycline antibiotic, in the environment has drawn increasing attention in recent years due to its wide usage. Little is known about the biodegradability of DC in the environment. The objective of this study was to characterize the biotransformation of DC by pure bacterial strains with respect to reaction kinetics under different environmental conditions and biotransformation products. Two bacterial strains, Brevundimonas naejangsanensis DD1 and Sphingobacterium mizutaii DD2, were isolated from chicken litter and characterized for their biotransformation capability of DC. Results show both strains rely on cometabolism to biotransform DC with tryptone as primary growth substrate. DD2 had higher biotransformation kinetics than DD1. The two strains prefer similar pHs (7 and 8) and temperature (30 °C), however, they exhibited opposite responses to increasing background tryptone concentration. While hydrolysis converted DC to its isomer or epimer, the two bacterial strains converted DC to various biotransformation products through a series of demethylation, dehydration, decarbonylation and deamination. Findings from the study can be used to better predict the fate of DC in the environment.

Occurrence of typical antibiotics, representative antibiotic-resistant bacteria, and genes in fresh and stored source-separated human urine

Human urine is a source of fertilizer and, with proper management, it can be reused in agriculture. Determining the contamination issue of antibiotics in source-separated urine is important because the majority of antibiotics are excreted with urine. In this study, source-separated urine samples were randomly collected from a male toilet in a university building and analyzed in terms of 30 typical antibiotics (including 14 sulfonamides, 4 tetracyclines, and 12 fluoroquinolones) and tetracycline-resistant Escherichia coli, as well as its antibiotic-resistant genes to determine the contamination characteristics of antibiotic-related pollution in fresh and stored urine. Results showed that 18 out of 30 typical antibiotics were detected in fresh source-separated human urine. The dominant antibiotic was oxytetracycline with a frequency of 100%, followed by tetracycline, sparfloxacin, enrofloxacin, and ofloxacin, which demonstrated a detection frequency of 55%. Among the detected values, sulfonamides (2 antibiotics), tetracyclines (4 antibiotics), and fluoroquinolones (12 antibiotics) had a concentration range of 0.25-2.94, 0.94-41.2, and 0.06-163.16 ng/mL, respectively. Furthermore, tetracycline-resistant Escherichia coli, which was measured using plate count method, and its related gene, tet M, exhibited a maximum cell density of (200,000 ± 5000) CFU/100 mL and (2.73 ± 0.261) × 10⁷ copies/mL, respectively. When the fresh urine was stored in an ambient environment for 30 days to simulate the real circumstances of urine management, a significant reduction in antibiotics and antibiotic-resistant bacteria was observed, while the change in antibiotic-resistant genes was insignificant. The results of this study suggest that risks associated with antibiotics and their antibiotic-resistant bacteria and genes are retained during collection and storage. Hence, these kinds of microcontaminants must be considered in further urine utilization.

Laccases and peroxidases: The smart, greener and futuristic biocatalytic tools to mitigate recalcitrant emerging pollutants

Various organic pollutants so-called emerging pollutants (EPs), including active residues from pharmaceuticals, pesticides, surfactants, hormones, and personal care products, are increasingly being detected in numerous environmental matrices including water. The persistence of these EPs can cause adverse ecological and human health effects even at very small concentrations in the range of micrograms per liter or lower, hence called micropollutants (MPs). The existence of EPs/MPs tends to be challenging to mitigate from the environment effectively. Unfortunately, most of them are not removed during the present-day treatment plants. So far, a range of treatment processes and degradation methods have been introduced and deployed against various EPs and/or MPs, such as ultrafiltration, nanofiltration, advanced oxidation processes (AOPs) and enzyme-based treatments coupled with membrane filtrations. To further strengthen the treatment processes and to overcome the EPs/MPs effective removal dilemma, numerous studies have revealed the applicability and notable biocatalytic potentialities of laccases and peroxidases to degrade different classes of organic pollutants. Exquisite selectivity and unique catalytic properties make these enzymes powerful biocatalytic candidates for bio-transforming an array of toxic contaminants to harmless entities. This review focuses on the use of laccases and peroxidases, such as soybean peroxidase (SBP), horseradish peroxidase (HRP), lignin peroxidase (LiP), manganese peroxidase (MnP), and chloroperoxidase (CPO) as a greener oxidation route towards efficient and effective removal or degradation of EPs/MPs.

Advanced Oxidation Processes for the Removal of Antibiotics from Water. An Overview

In this work, the application of advanced oxidation processes (AOPs) for the removal of antibiotics from water has been reviewed. The present concern about water has been exposed, and the main problems derived from the presence of emerging pollutants have been analyzed. Photolysis processes, ozone-based AOPs including ozonation, O3/UV, O3/H2O2, and O3/H2O2/UV, hydrogen peroxide-based methods (i.e., H2O2/UV, Fenton, Fenton-like, hetero-Fenton, and photo-Fenton), heterogeneous photocatalysis (TiO2/UV and TiO2/H2O2/UV systems), and sonochemical and electrooxidative AOPs have been reviewed. The main challenges and prospects of AOPs, as well as some recommendations for the improvement of AOPs aimed at the removal of antibiotics from wastewaters, are pointed out.

A novel antibiotic wastewater degradation technique combining cavitating jets impingement with multiple synergetic methods

Antibiotics degradation remains a longstanding challenge in wastewater treatment. Towards this objective, we have developed a novel technique combining cavitating jets impingement with multiple synergetic methods, i.e., UV/Fenton, analogous Fenton, and photocatalytic oxidation in the present work. Three kinds of antibiotics namely amoxicillin, doxycycline and sulfadiazine sodium, are selected as model pollutants. Individual application of cavitating jets impingement is firstly conducted to evaluate the effects of jets impinging forms and nozzle inlet pressure. The effects of impingement on promoting antibiotics degradation and weakening the coalescing effects of cavitation bubbles are confirmed. Perpendicular double cavitating jets impingement is proved to be the most effective impinging form and brought a COD (chemical oxidation demand) reduction of 30.04% with the impinging effect index 1.22 at jet inlet pressure 10 MPa. Increasing the jet inlet pressure can improve the COD reduction and the effectiveness of impingement. Subsequently, UV/Fenton process is introduced to intensify the degradation process. The effects of important parameters are investigated by means of orthogonal experiments and the maximum COD reduction is up to 71.16% under the optimum conditions. Then, analogous Fenton process and photocatalytic oxidation are adopted for further enhancing the COD reduction. Different approaches used in the present work are assessed in view of multiple aspects. With COD reduction of 79.92%, the combination of cavitating jets impingement, UV/Fenton, analogous Fenton and photocatalytic oxidation is proved to be optimum method for antibiotic wastewater treatment.