Emerging Pollutants In Water Research Articles

Machine learning-assisted source tracing in domestic-industrial wastewater: A fluorescence information-based approach

An emergency water pollution incident poses a significant risk to the proper functioning of wastewater treatment plants, particularly in domestic-industrial integrated facilities. Source tracing is recognized as an effective method to mitigate ongoing impacts. Machine learning-assisted traceability is emerging as a more efficient and faster method compared to traditional methods. In this study, a total of 712 sets of characterization wastewater information from effluent samples from14 discharge enterprises across 6 different sectors, as well as domestic wastewater was collected using 3-dimensional fluorescence spectroscopy. After data cleaning and augmentation, a feature fingerprint database of wastewater was constructed to train a traceability model. Several machine learning algorithms, including Back Propagation neural network (BP), Random Forest (RF), Support Vector Machine (SVM), Naive Bayes (NB) and K-Nearest Neighbors (KNN), were selected for constructing the traceability framework. Subsequently, an advanced Particle Swarm Optimization Random Forest model (PSO-RF), capable of automatically optimizing model parameters, was proposed and applied to trace the sources of wastewater in integrated wastewater treatment plant. The PSO-RF achieved and accuracy of 96.55 % in sector identification and 94.25 % in manufacturer identification. As part of the validation process, laboratory simulations were conducted using blended wastewater with different volume ratios of domestic and industrial wastewater to evaluated the potential application of PSO-RF. The results consistently demonstrated PSO-RF's effectiveness, particularly in tracing pharmaceutical wastewater sources, maintaining an accuracy of over 85 %. This work presents a novel strategy for tracing abnormal sources during emergency pollutant incidents, providing essential support for integrating artificial intelligence (AI) into meticulous wastewater management.

Physicochemical study of the adsorption of chlorophenols on activated carbon using an advanced double layer model

An advanced theoretical analysis was performed to elucidate the adsorption of 2,4-dichlorophenol and 4-chlorophenol on an activated carbon obtained from pine sawdust. In particular, a double layer adsorption model was used to estimate the number of chlorophenols molecules adsorbed per activated carbon functional group, the concentration of active sites from activated carbon surface involved in the adsorption mechanism, the saturation adsorption capacities and interaction energies to form the adsorbate layers on activated carbon. This theoretical investigation showed that the saturation adsorption capacities for the removal of 2,4-dichlorophenol and 4-chlorophenol were 167 and 130 mg/g, respectively. The adsorption of 2,4-dichlorophenol on activated carbon outperformed the 4-chlorophenol adsorption under tested experimental conditions. The adsorption of these compounds was endothermic and governed mainly by van der Waals interactions and hydrogen bonding. The adsorption of 2,4-dichlorophenol on activated carbon was a multimolecular process with the presence of an aggregation process in the aqueous solution, while a multi-docking adsorption mechanism occurred for the removal of 4-chlorophenol. Overall, this study contributes with theoretical insights on the removal of two emerging water pollutants by using activated carbon.

Monte Carlo Simulations of Water Pollutant Adsorption at Parts-per-Billion Concentration: A Study on 1,4-Dioxane.

1,4-dioxane, an emerging water pollutant with high production volumes, is a probable human carcinogen. The inadequacy of conventional treatment processes demonstrates the need for an effective remediation strategy. Crystalline nanoporous materials are cost-effective adsorbents due to their high capacity and selective separation in mixtures. This study explores the potential of all-silica zeolites for the separation of 1,4-dioxane from water. These zeolites are highly hydrophobic and can preferentially adsorb nonpolar molecules from mixtures. We investigated six zeolite frameworks (BEA, EUO, FER, IFR, MFI, and MOR) using Monte Carlo simulations in the Gibbs ensemble. The simulations indicate high selectivity by FER and EUO, especially at low pressures, which we attribute to pore sizes and shapes with a greater affinity to 1,4-dioxane. We also demonstrate a Monte Carlo simulation workflow using gauge cells to model the adsorption of an aqueous solution of 1,4-dioxane at a 0.35 ppb concentration. We quantify 1,4-dioxane and water coadsorption and observe selectivities ranging from 1.1 × 105 in MOR to 8.7 × 106 in FER. We also demonstrate that 1,4-dioxane is in the infinite dilution regime in the aqueous phase at this concentration. This simulation technique can be extended to model other emerging water contaminants such as perfluoroalkyl and polyfluoroalkyl substances (PFAS), chlorofluorocarbons, and others, which are also found in extremely low concentrations.

Noteworthy synthesis strategies and applications of metal-organic frameworks for the removal of emerging water pollutants from aqueous environment

17 global Sustainable Development Goals (SDGs) were established through the adoption of the 2030 Agenda for Sustainable Development by all United Nations members. Clean water and sanitation (SDG 6) and industry, innovation, and infrastructure (SDG 9) are the SDGs focus of this work. Of late, various new companies delivering metal-organic frameworks (MOFs) have blossomed and moved the field of adsorption utilizing MOFs to another stage. Inside this unique circumstance, this article aims to catch recent advancements in the field of MOFs and the utilizations of MOFs relate to the expulsion of arising contaminations that present huge difficulties to water quality because of their steadiness and possible damage to environments and human wellbeing. Customary water treatment techniques regularly neglect to eliminate these poisons, requiring the advancement of novel methodologies. This study overviews engineering techniques for controlling MOF characteristics for better flexibility, stability, and surface area. A current report on MOFs gathered new perspectives that are amicably discussed in emergent technologies and extreme applications towards environmental sectors. Various applications in many fields that exploit MOFs are being fostered, including gas storage, fluid separation, adsorbents, catalysis, medication delivery, and sensor utilizations. The surface area of a wide range of MOFs ranges from 103 to 104 m2/g, which exceeds the standard permeability of several material designs. MOFs with extremely durable porosity are more significant in their assortment and variety than other classes of porous materials. The work outlines the difficulties encountered in the synthesis steps and suggests ways to make use of MOFs' value in a variety of contexts. This caters to creating multivariate systems enclosed with numerous functionalities, leading to the synthesis of MOFs that offer a synergistic blend of in-built properties and exclusive applications. Additionally, the MOF-related future development opportunities and challenges are discussed.

Selection of a new aptamer targeting amoxicillin for utilization in a label-free electrochemical biosensor

Pharmaceutical pollution has received considerable attention because of the harmful effects of pharmaceutical compounds on human health, even in trace amounts. Amoxicillin is one of the frequently used antibiotics that was included in the list of emerging water pollutants. Therefore, a highly selective and rapid technique for amoxicillin detection is required. In this work, a new aptamer was selected for amoxicillin and utilized for the development of a label-free electrochemical aptasensor. Aptamer selection was performed using the systematic evolution of ligands by exponential enrichment. The selected aptamer showed good specificity against other antibiotics, including the structurally related antibiotics: ampicillin and ciprofloxacin. Among the selected aptamers, Amx3 exhibited the lowest dissociation constant value of 112.9 nM. An aptasensor was developed by immobilization of thiolated Amx3 aptamer onto gold screen–printed electrodes via self-assembly, which was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The detection was realized by monitoring the change in the differential pulse voltammetry peak current in the ferro/ferricyanide redox couple upon binding of the aptasensor to amoxicillin. The aptasensor showed very good sensitivity with an ultralow limit of detection of 0.097 nM. When the aptasensor was tested using actual spiked milk samples, excellent recovery percentages were observed. The label-free electrochemical aptasensor developed herein is a promising tool for the selective and sensitive detection of amoxicillin in environmental samples.

Adsorption separation of oxytetracycline hydrochloride using natural and nanostructured clay mineral of silica in synthetic solution: Integration to white and green chemistry metrics

As emerging water pollutants, oxytetracycline (OTC) and its derivatives are detrimental to humans, organisms, and aquatic ecosystems. Oxytetracycline hydrochloride (OTCH) was effectively absorbed from water by silica (SiO2) and metakaolinite (MK). In this study, we employed a unique metric known as BAGI to evaluate the suggested analytical method's suitability effectively. Blue applicability grade index (BAGI) complements green assessment tools such as the Green analytical procedure index (GAPI), Complex green analytical procedure index ComplexGAPI, Analytical GREEnness (AGREE), Analytical greenness for sample preparation (AGREEprep), and Analytical eco-scale (ESA). The BAGI metric focuses on the practical aspects of white analytical chemistry, especially those related to “blue.” The optimal parameters for adsorbing OTCH were determined by a study (pH, OTCH concentration at the beginning of the reaction, sorbent dose, and reaction duration). This study of sorbent properties was conducted via X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The highest levels of OTCH adsorption were seen at pH 5–6 for MK and at pH 7 for SiO2. The most desirable clay minerals are those with smaller quantities. The Langmuir model accurately characterizes the results, showing a strong correlation between OTCH sorption onto MK with a maximum capacity of 165.04 mg/g and a moderate correlation for SiO2 with a maximum capacity of 25.3 mg/g. Therefore, these findings regarding the effectiveness of adsorption and the analysis of properties offer supplementary insights into the potential use of clay minerals as cost-effective and eco-friendly sorbents for treating wastewater.

Innovative syntheses of immobilized CuxO semiconductors grown on 3D prints and their photoelectrochemical activity for sulfamethoxazole degradation

Traditional copper oxide manufacturing processes require high energy consumption, high synthesis temperatures, and long process times. This study proposes an innovative additive manufacturing process to support immobilized copper oxide, offering greater design flexibility and customization. CuxO semiconductors were synthesized on 3D-printed substrates via the anodization process and evaluated for their effectiveness in degrading sulfamethoxazole (SMX). XRD analysis of the samples revealed the presence of both CuO and Cu2O crystalline phases, this mixture of oxides helps to expand the absorption range of visible light. The immobilized CuxO semiconductors exhibited band gaps ranging between 1.6 and 1.8 eV. Negative current densities and Mott-Schottky analysis confirmed the nature of the p-type semiconductor. Semiconductors grown by 3D printing demonstrated remarkable degradation capacity for the antibiotic sulfamethoxazole (SMX), achieving 60% degradation after 360 minutes under visible light. Kinetic degradation tends to be a first-order and zero-order model. TOC analysis further revealed the formation of reaction intermediates during SMX degradation, ultimately leading to the mineralization of the contaminant. Based on these results, we report, for the first time CuxO semiconductors grown on large 3D-printed substrates as promising photocatalysts for the degradation of emerging water pollutants. Based on these results, we report, for the first time, that CuxO semiconductors grown on large 3D-printed substrates are promising photocatalysts for the degradation of emerging water contaminants. Furthermore, it should be emphasized that the proposed method is faster and does not require subsequent thermal treatments for its functionalization, making it attractive for various industrial applications.

Molecularly imprinted polymers as solid-phase and dispersive solid-phase extraction sorbents in the extraction of antiretroviral drugs in water: adsorption, selectivity and reusability studies

AbstractThe antiretroviral drugs (ARVDs) have been reported to be among the emerging water pollutants as a results attention is being paid on their analysis. This work therefore explored for the first time the multi-template MIP for the selective removal of selected ARVDs (abacavir, efavirenz and nevirapine) in wastewater, river water and tap water. The adsorption studies of a multi-template MIP were conducted by determining the effect of an increase in ARVDs concentration in solution and the effect of an increase in contact time between the sorbent and the ARVDs. High adsorption efficiencies were observed for abacavir, efavirenz and nevirapine analytes within 5 min and the maximum adsorption efficiency was observed at 60 min ranging from 94.76 to 96.93%. Adsorption kinetics showed that pseudo-second rate order was the best fitting model, while adsorption isotherms indicated that the Freundlich isotherm (R2 = 0.94–0.98) best described the adsorption mechanism of ARVDs onto the MIPs. These results indicated that the electrostatic attractions influenced the multilayer coverage and chemisorption process. Selectivity studies conducted in the presence of competitors gave the recoveries between 92 and 98% for the target analytes, while they were 63–79% for competitors indicating good selectivity and strong affinity of the polymer towards the target analytes. Reusability studies showed that the MIP can be reused for up to 8 cycles with recoveries above 92% for all target ARVDs. The application of the MIP-DSPE method to wastewater, river and tap water samples gave concentrations of 28.75–178.02, 1.95–13.15 and 2.17–6.27 µg L−1, respectively. These results indicate the potential unplanned consumption of ARVDs upon drinking contaminated water which could result to their resistance by the human body. Therefore, their continuous monitoring as well as investigation of their removal strategies is of paramount importance.

Carbon nitride- and graphene-based materials for the photocatalytic degradation of emerging water pollutants

This review highlights several advantages and improvement strategies for carbon nitride as a visible light-active photocatalyst and graphene derivatives as a supporting material for the photocatalytic degradation of emerging water pollutants.

Dual function of ultra-laminated hydrotalcite in environmental remediation: Adsorption of water contaminant BP-4 and reutilization of the adsorption product for photocatalytic NOx air decontamination

UV filters are a class of emerging water pollutants used in cosmetics to protect the skin from ultraviolet radiation. This work appraises the uptake of benzophenone-4 (BP-4), widely used and highly soluble sunscreen agent, by its adsorption on hydrotalcite based compounds. The studied adsorbents were hydrotalcite Mg3Al-CO3 (HT), ultra-laminated hydrotalcite (UHT) prepared by “Aqueous Miscible Organic Solvent Treatment” and their calcined products (HT500 and UHT500, respectively). Adsorbents were characterised by different techniques such as XRD, TEM, FT-IR, BET, XRF and TGA. The most remarkable feature was the enhancement in the specific surface area (SSA) of the ultra-laminated hydrotalcite samples, UHT and UHT500 with values of 212 m2·g─1 and 247 m2·g─1, respectively. Adsorption capacities decreased from very high for UHT500 to low values for HT in order UHT500 > HT500 > UHT > HT. The results showed that not only the SSA values were relevant for adsorbing BP-4, but also other factors such as anionic exchange capacity (AEC) and surface charge. In addition, the adsorption product (UHT-BP4) was evaluated as a photocatalyst for air purification, exhibiting good efficiency for the removal of atmospheric pollutants such as NOx gases.

Sheet-like graphitized glucose-based mesoporous carbon for aqueous adsorption of tetracycline antibiotic

Antibiotics are an emerging water pollutant without universally agreed regulations. Hence, its removal from the water will minimize antibiotics resistance bacteria. Herein, facile pyrolysis at 500 °C for 3 h was deployed to convert d-glucose to sheet-like graphitized carbon (GLU-500) for the removal of tetracycline antibiotics. The carbon material was characterized and the effect of pH, contact time, and initial concentration of tetracycline was elucidated. Results revealed that pyrolysis temperature tailored the morphology, functional group, and textural characteristics to accumulate a high amount of tetracycline. Electrostatic attraction at a pH of 5 favored the highest removal of 138.32 mg g−1of tetracycline at 30 °C, however, this adsorption capacity declined at increasing pH due to the formation of zwitterions that imposes a diffusion barrier. A multilayer adsorption was observed for the tetracycline-GLU-500 system, which was best described by Freundlich isotherm with R2 of 0.94−0.99. Also, the pseudo-second-order kinetic model confirms that thetetracycline-GLU-500 system adsorption is mainly by chemical interaction. The study confirms that abundant glucose can be a sustainable precursor for treatment of antibiotics contaminated water.

Biosafe removal of diclofenac from wastewaters by a continuous-flow mode cold atmospheric pressure plasma system

Diclofenac (DCF) is not only a versatile non-steroidal anti-inflammatory drug, but also an emerging water pollutant. There is an urgent need for innovative technology of wastewater treatment to reduce the impact of DCF on the environment. Thus, we examined the applicability of pulse-modulated radio-frequency atmospheric pressure glow discharge (pm-rf-APGD) for degradation of 1.56–50.0 mg L-1 DCF from both aqueous solutions and synthetic wastewaters. The removal rates varied from 84.0 ± 3.8% to 100.0 ± 0.1% for the aqueous solution and increased together with the decreasing concentration of DCF. For synthetic wastewaters, the DCF removal was enclosed in the range from 21.0 ± 1.0% to 74.8 ± 0.1%. The energy efficiencies varied from 0.0116 to 0.312 g kW-1h-1 for aqueous solutions and from 0.00779 to 0.0087 g kW-1h-1 for synthetic wastewaters, respectively. By application of ultraperformance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS), the pm-rf-APGD-driven DCF degradation pathways were revealed to involve decomposition, nitration, and dehalogenation reactions yielding dichloroaniline, nitro-diclofenac and 8-chlorocarbazole-1-acetic acid, respectively, before achieving the total decomposition of DCF to carbon dioxide, water, chlorides, nitrates and amines. Notable increases in the contents of the radicals, i.e., H2O2 in addition to NO2- and NO3-, were observed in the plasma-treated DCF solutions in contrast to the controls. Finally, no cytotoxic activity of the pm-rf-APGD-treated DCF solutions was demonstrated on model non-malignant human endothelial cells (HUVEC) and human immortalized keratinocytes (HaCaT). We anticipate that the described continuous-flow pm-rf-APGD-based reaction discharge system might be applied for biosafe removal of DCF from the effluents originating from wastewater treatment plants.

Fixed-bed adsorption studies of endocrine-disrupting compounds from water by using novel calcium-based metal-organic frameworks

The presence of emerging water pollutants such as endocrine-disrupting compounds (EDCs), including 17-ethynylestradiol (EE2), bisphenol A (BPA), and perfluorooctanoic acid (PFOA), in contaminated water sources poses significant environmental and health challenges. This study aims to address this issue by investigating the efficiency of novel calcium-based metal-organic frameworks, known as mixed-linker calcium-based metal-organic frameworks (Ca-MIX), in adsorbing these endocrine-disrupting compounds. This study analyzed the influence of influent concentration, bed height, and flow rate on pollutant removal, with bed height emerging as a crucial factor. From the breakthrough curves, it was determined that the column maximum adsorption capacities followed the order of 17-ethynylestradiol (101.52 μg/g; 40%) > bisphenol A (99.07 μg/g; 39%) > perfluorooctanoic acid (81.28 μg/g; 32%). Three models were used to predict the adsorption process, with the Yan model outperforming the other models. This suggests the potential of mixed-linker calcium-based metal-organic frameworks for removing endocrine-disrupting compounds from water, using the Yan model as an effective predictor. Overall, this study provides valuable insights for the development of effective water treatment methods using mixed-linker calcium-based metal-organic frameworks to remove endocrine-disrupting compounds from contaminated water sources.

Hydroxyl radical-driven transformations of bisphenol A and 2,4-dinitroanisole: Experimental and computational analysis.

This study used experimental and computational analysis to investigate the advanced oxidation of bisphenol A (BPA) and 2,4-dinitroanisole (DNAN). The pseudo first-order reaction rate constants depended on the molar peroxide ratio and were between 0.13 and 0.28 min-1 for BPA and between 0.018 and 0.032 min-1 for DNAN. The kinetic differences appear to be due in part to the energy requirements for oxidation, which depended on the reaction mechanism but were typically lower for BPA than they were for DNAN. Density functional theory (DFT) was used to develop transformation pathways that included experimentally-detected byproducts. The most energetically favored pathway for BPA oxidation begins with the formation of hydroxylated derivatives, while for DNAN, the most energetically favorable degradation pathway begins with the substitution of the methoxy group. Overall, these findings demonstrate the power of combining experimental and computational tools to reveal transformation mechanisms during water treatment. PRACTITIONER POINTS: Advanced oxidation transformations for two emerging water pollutants, bisphenol A and dinitroanisole, was investigated. The observed reaction kinetics depended on molar peroxide ratio in a manner that is in keeping with previous findings. Density functional theory-based analysis revealed reaction energy requirements and degradation pathways.

Catalytic Activity of Rare Earth Elements (REEs) in Advanced Oxidation Processes of Wastewater Pollutants: A Review.

In recent years, sewage treatment plants did not effectively remove emerging water pollutants, leaving potential threats to human health and the environment. Advanced oxidation processes (AOPs) have emerged as a promising technology for the treatment of contaminated wastewater, and the addition of catalysts such as heavy metals has been shown to enhance their effectiveness. This review focuses on the use of rare earth elements (REEs) as catalysts in the AOP process for the degradation of organic pollutants. Cerium and La are the most studied REEs, and their mechanism of action is based on the oxygen vacancies and REE ion concentration in the catalysts. Metal oxide surfaces improve the decomposition of hydrogen peroxide to form hydroxide species, which degrade the organics. The review discusses the targets of AOPs, including pharmaceuticals, dyes, and other molecules such as alkaloids, herbicides, and phenols. The current state-of-the-art advances of REEs-based AOPs, including Fenton-like oxidation and photocatalytic oxidation, are also discussed, with an emphasis on their catalytic performance and mechanism. Additionally, factors affecting water chemistry, such as pH, temperature, dissolved oxygen, inorganic species, and natural organic matter, are analyzed. REEs have great potential for enhancing the removal of dangerous organics from aqueous solutions, and further research is needed to explore the photoFenton-like activity of REEs and their ideal implementation for wastewater treatment.

Development and application of a multi-centre cloud platform architecture for water environment management

To promote the intelligent and accurate management of river basins, especially large basins which involve many catchments, it is highly required to develop a useful platform to effectively coordinate arithmetic resources and data, and simultaneously help to make decisions based on the real-time calculation. In this study, a multi-centre cloud platform architecture called 3L4C was constructed, which includes a Cloud-edge-terminal Layer (3L), data centre, model centre, control centre, and customer-service centre (4C). Data fusion technology and an air-land-water coupled model were constructed. Based on HTML5, JavaScript, and Java, an integrated water environment management platform was created and applied to the Three Gorges Reservoir Basin, China. The platform was tested and successfully used for automatic water quality prediction, water environment pollution analysis and control, early warning of abnormal water quality, and emergency water pollution incident evaluation. This platform quickly and accurately forecasts and perfectly displays past, present and future state of the water environment, and offers beneficial support for management decisions in various water environment departments.

Theoretical verification on adsorptive removal of caffeine by carbon and nitrogen-based surfaces: Role of charge transfer, π electron occupancy, and temperature

Eliminating an emerging water pollutant, caffeine molecules, from an aqueous solution using carbon and nitrogen-based adsorbents is of significant interest to public health. These adsorbents have been shown to have decent adsorption capacity toward caffeine due to their surface functionality. Therefore, screening various carbon and nitrogen-based surfaces can be a better option for high-performance adsorbents to remove caffeine efficiently from wastewater. Herein, we present combined first principles and molecular dynamics quantification of the adsorption enthalpies of caffeine molecules on the possible active sites of carbon and nitrogen-based adsorbents (graphene, phagraphene, graphdiyne, single-wall carbon nanotube, fullerene, and graphitic carbon nitride) with the incorporation of Van der Waals interactions. From the DFT calculations, N-doped carbon surfaces show the highest adsorption energies of single and dimer CAF compared to pristine carbon-based adsorbents. A charge density difference and Bader charge analysis display that high charge transfer occurs between the caffeine's oxygen and the surface's nitrogen atoms. An abundance of π-electrons from the nitrogen atoms, composed of large electron clouds of aromatic rings on the graphitic carbon surface, tends to favor extensive π-π interactions with the caffeine molecule. The high value of pz electron occupancy (1.445) of N in the hexagonal ring of the graphitic surface transfers additional charge transfer, which leads to strong adsorption energy of CAF than pristine surfaces. Also, the g-C3N4 surface adsorbs the CAF molecule with higher adsorption than other N-doped carbon surfaces due to the high pz_eo (1.5448) of N atoms on the surface. At 310 K, the water molecules' kinetics aids the single and dimer caffeine molecules to adsorb with the highest adsorption energies on the active sites of g-C3N4 surfaces than graphene adsorbent.

Theoretical investigation on the degradation of sulfadiazine in water environments: Oxidation of •OH, SO4•−and CO3•− and reactivity of (TiO2)n clusters (n = 1–6)

This study reported the degradation of micro pollutants through reactive radicals like •OH, SO4•−and CO3•−. Sulfadiazine (SDZ) is widely used antibiotic and emerging water pollutant. The synergistic degradation of sulfadiazine by •OH, SO4•−and CO3•− was investigated through quantum chemistry methods. The degradation of SDZ by •OH radicals was dependent on radical adduct formation (RAF) reactions while degradation of SDZ by SO4•− radical was caused by RAF, hydrogen atom transfer (HAT) and also single electron transfer (SET). The degradation of SDZ by CO3•− radical mainly caused by RAF and HAT. The degradation rate constants of SDZ initiated through •OH, SO4•−and CO3•− radicals were calculated separately: kSDZ-SO4•− (5.29 × 1010 M−1 s−1) > kSDZ-•OH (1.38 × 1010 M−1 s−1) > kSDZ-CO3•− (1.28 × 108 M−1 s−1). The degradation mechanism of SDZ by (TiO2)n (n = 1–6) cluster was investigated. The conformation between benzene ring and heterocyclic ring of SDZ has a lower adsorption energy and the (TiO2)n cluster (n = 5) is the most stable adsorption conformation with SDZ. The toxicity assessment showed that most of the degradation products were less toxic and eco-friendly. However, O-P1, P4 and P9 exhibited more severe aquatic toxicity.

Potential degradation of norfloxacin using UV-C/Fe2+/peroxides-based oxidative pathways

• Different peroxides-based oxidative pathways were compared towards NOR degradation. • The peroxide HSO 5 − performed best in the degradation of NOR under UV-C and Fe 2+ . • The peroxides yield ● OH and SO 4 ●− under activation by UV-C and Fe 2+ activation. • The ● OH and SO 4 ●− scavengers inhibited degradation of NOR. • Degradation products and ecotoxicities of NOR as well as its DPS were estimated. The removal of norfloxacin (NOR), a widely used pharmaceutical and emerging water pollutant, was studied using UV-C and Fe 2+ catalyzed peroxides-based oxidative processes (e.g., UV-C/Fe 2+ /H 2 O 2 , UV-C/Fe 2+ /S 2 O 8 2− and UV-C/Fe 2+ /HSO 5 − ) and compared with UV-C and UV-C/Fe 2+ . The UV-C and UV-C/Fe 2+ degraded NOR to 38 and 55%. However, use of peroxides, i.e., H 2 O 2 , S 2 O 8 2− , HSO 5 − with UV-C and UV-C/Fe 2+ promoted NOR %degradation to 75, 83, and 90% using [peroxides] 0 = 50 mg/L, [Fe 2+ ] 0 = 1 mg/L, and [NOR] 0 = 10 mg/L, respectively. The significant impact of peroxides on NOR degradation was due to their decomposition into ● OH and SO 4 ●− which showed high activity towards NOR degradation. The ● OH and SO 4 ●− formation from peroxides decomposition and their contribution in NOR degradation was verified by different scavenger studies. Among the UV-C/Fe 2+ /peroxides processes, UV-C/Fe 2+ /HSO 5 − showed better performance. The changing concentrations of peroxides, Fe 2+ , and NOR affected degradation of NOR. The use of different pH and inorganic anions also influenced NOR degradation. The degradation pathways of NOR were established and analyzed acute as well as chronic toxicities of NOR and its DPs.

Specific Surface Area Versus Adsorptive Capacity: an Application View of 3D Graphene-Based Materials for the Removal of Emerging Water Pollutants

Specific Surface Area Versus Adsorptive Capacity: an Application View of 3D Graphene-Based Materials for the Removal of Emerging Water Pollutants