Iron-impregnated zeolite catalyst for efficient removal of micropollutants at very low concentration from Meurthe river

Effect of copper doping on the photocatalytic performance of Ni2O3@PC membrane composites in norfloxacin degradation

In this study, copper (Cu) and nickel oxide (Ni2O3) microtubes (MTs) were synthesized using an electroless template deposition technique within porous polycarbonate (PC) track-etched membranes (TeMs) to obtain Cu@PC and Ni2O3@PC composite membranes, respectively. The pristine PC TeMs featured nanochannels with a pore density of 4 × 107 pores per cm2 and an average pore diameter of 400 ± 13 nm. The synthesis of a mixed composite, combining Cu and Ni2O3 within the PC matrix, was achieved through a two-step deposition process using a Ni2O3@PC template. An analysis of the resultant composite structure (Cu/Ni2O3@PC) confirmed the existence of CuNi (97.3%) and CuO (2.7%) crystalline phases. The synthesized catalysts were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) analysis, and atomic force microscopy (AFM). In photodegradation assessments, the Cu/Ni2O3@PC mixed composite demonstrated higher photocatalytic activity, achieving a substantial 59% degradation of norfloxacin (NOR) under UV light irradiation. This performance surpassed that of both Ni2O3@PC and Cu@PC composites. The optimal pH for maximum NOR removal from the aqueous solution was determined to be pH 5, with a reaction time of 180 min. The degradation of NOR in the presence of these composites adhered to the Langmuir-Hinshelwood mechanism and a pseudo-first order kinetic model. The reusability of the catalysts was also investigated for 10 consecutive runs, without any activation or regeneration treatments. The Cu@PC membrane catalyst demonstrated a marked decline in degradation efficiency after the 2nd test cycle, ultimately catalyzing only 10% of NOR after the 10th cycle. In contrast, the Ni2O3@PC based catalyst demonstrated a more stable NOR degradation efficiency throughout all 10 runs, with 27% NOR removal observed during the final test. Remarkably, the catalytic performance of the Cu/Ni2O3@PC mixed composite remained highly active even after being recycled 4 times. The degradation efficiency exhibited a gradual reduction, with a 17% decrease after the 6th run and a cumulative 35% removal of NOR achieved by the 10th cycle. Overall, the findings indicate that Cu/Ni2O3@PC mixed composite membranes may represent an advancement in the quest to mitigate the adverse effects of antibiotic pollution in aquatic environments and hold significant promise for sustainable water treatment practices.

The beneficial role of nano-sized Fe3O4 entrapped in ultra-stable Y zeolite for the complete mineralization of phenol by heterogeneous photo-Fenton under solar light

Highly efficient, separable, and stable magnetic iron-based-photocatalysts produced from ultra-stable Y (USY) zeolite were applied, for the first time, to the photo-Fenton removal of phenol under solar light. USY Zeolite with a Si/Al molar ratio of 385 was impregnated under vacuum with an aqueous solution of Fe2+ ions and thermally treated (500-750 °C) in a reducing atmosphere. Three catalysts, Fe-USY500°C-2h, Fe-USY600°C-2h and Fe-USY750°C-2h, containing different amounts of reduced iron species entrapped in the zeolitic matrix, were obtained. The catalysts were thoroughly characterized by absorption spectrometry, X-ray powder diffraction with synchrotron source, followed by Rietveld analysis, X-ray photoelectron spectroscopy, N2 adsorption/desorption at -196 °C, high-resolution transmission electron microscopy and magnetic measurements at room temperature. The catalytic activity was evaluated in a recirculating batch photoreactor irradiated by solar light with online analysis of evolved CO2. Photo-Fenton results showed that the catalyst obtained by thermal treatment at 500 °C for 2 h under a reducing atmosphere (FeUSY-500°C-2h) was able to completely mineralize phenol in 120 min of irradiation time at pH = 4 owing to the presence of a higher content of entrapped nano-sized magnetite particles. The latter promotes the generation of hydroxyl radicals in a more efficient way than the Fe-USY catalysts prepared at 600 and 750 °C because of the higher Fe3O4 content in ultra-stable Y zeolite treated at 500 °C. The FeUSY-500°C-2h catalyst was recovered from the treated water through magnetic separation and reused five times without any significant worsening of phenol mineralization performances. The characterization of the FeUSY-500°C-2h after the photo-Fenton process demonstrated that it was perfectly stable during the reaction. The optimized catalyst was also effective in the mineralization of phenol in tap water. Finally, a possible photo-Fenton mechanism for phenol mineralization was assessed based on experimental tests carried out in the presence of scavenger molecules, demonstrating that hydroxyl radicals play a major role.

Recent trends in degradation strategies of PFOA/PFOS substitutes

The global elimination and restriction of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), respectively, have urged manufacturers to shift production to their substitutes which still pose threat to the environment with their bioaccumulation, toxicity and migration issues. In this context, efficient technologies and systematic mechanistic studies on the degradation of PFOA/PFOS substitutes are highly desirable. In this review, we summarize the progress in degrading PFOA/PFOS substitutes, including four kinds of mainstream methods. The pros and cons of the present technologies are analyzed, which renders the discussion of future prospects on rational optimizations. Additional discussion is made on the differences in the degradation of various kinds of substitutes, which is compared to the PFOA/PFOS and derives designing principles for more degradable F-containing compounds.

Adsorption of Carbamazepine in All-Silica Zeolites Studied with Density Functional Theory Calculations

The anticonvulsant drug carbamazepine (-) is an emerging contaminant of considerable concern due to its hazard potential and environmental persistence. Previous experimental studies proposed hydrophobic zeolites as promising adsorbents for the removal of carbamazepine from water, but only a few framework types were considered in those investigations. In the present work, electronic structure calculations based on dispersion-corrected density functional theory (DFT) were used to study the adsorption of CBZ in eleven all-silica zeolites having different pore sizes and connectivities of the pore system (AFI, ATS, BEA, CFI, DON, FAU, IFR, ISV, MOR, SFH, SSF framework types). It was found that some zeolites with one-dimensional channels formed by twelve-membered rings (IFR, AFI) exhibit the highest affinity towards CBZ. A "good fit" of CBZ into the zeolite pores that maximizes dispersion interactions was identified as the dominant factor determining the interaction strength. Further calculations addressed the role of temperature (for selected systems) and of guest-guest interactions between coadsorbed CBZ molecules. In addition to predicting zeolite frameworks of particular interest as materials for selective CBZ removal, the calculations presented here also contribute to the atomic-level understanding of the interaction of functional organic molecules with all-silica zeolites.

Environmental and Pharmacokinetic Aspects of Zeolite/Pharmaceuticals Systems—Two Facets of Adsorption Ability

Zeolites belong to aluminosilicate microporous solids, with strong and diverse catalytic activity, which makes them applicable in almost every kind of industrial process, particularly thanks to their eco-friendly profile. Another crucial characteristic of zeolites is their tremendous adsorption capability. Therefore, it is self-evident that the widespread use of zeolites is in environmental protection, based primarily on the adsorption capacity of substances potentially harmful to the environment, such as pharmaceuticals, pesticides, or other industry pollutants. On the other hand, zeolites are also recognized as drug delivery systems (DDS) carriers for numerous pharmacologically active agents. The enhanced bioactive ability of DDS zeolite as a drug carrying nanoplatform is confirmed, making this system more specific and efficient, compared to the drug itself. These two applications of zeolite, in fact, illustrate the importance of (ir)reversibility of the adsorption process. This review gives deep insight into the balance and dynamics that are established during that process, i.e., the interaction between zeolites and pharmaceuticals, helping scientists to expand their knowledge necessarily for a more effective application of the adsorption phenomenon of zeolites.

Effect of UV Irradiation on the Structural Variation of Metal Oxide-Silica Nanocomposites for Enhanced Removal of Erythromycin at Neutral pH

In this study, the effect of UV treatment on the physicochemical properties and structural variation of metal oxide-silica nanocomposites (Mn2O3-Fe2O3@SiO2) has been investigated. Based on the results, UV irradiation significantly affects the nanocomposite structure, where SiO2 network reconfiguration, change in surface OH group density, and surface area were observed. Erythromycin (ERY) has been chosen as a module pollutant to compare the performance of the pristine and UV-treated nanocomposites. The pristine nanocomposite had a high adsorption efficiency (99.47%) and photocatalytic activity (99.57%) at neutral pH for ERY in the first cycle, and this efficiency decreased significantly for the multiple cycles. However, different results have been observed for the UV-treated nanocomposite, where it retained its performance for ten consecutive cycles. This enhanced performance is attributed to the structural modifications after UV exposure, where increased surface area, pore volume, and OH group density resulted in an increased number of the possible mechanisms responsible for the adsorption/oxidation of ERY. Moreover, oxidation of adsorbed molecules by UV light after each cycle can also be another reason for enhanced removal. For the first time, the fate of ERY is studied using regenerated nanocomposites after the last cycle. LC/MS/MS results showed that ERY degraded in 20 min, and the produced reaction by-products were adsorbed by nanocomposites. This study could be a foundation research for the practical approaches for the regeneration of nanomaterials and the successful removal of organic pollutants from aquatic environments.

Developing Fe/zeolite catalysts for efficient catalytic wet peroxidation of three isomeric cresols

Five Fe/zeolite (i.e., Fe/ZSM-5-1, Fe/ZSM-5-2, Fe/ZSM-5-3, Fe/MCM-22, and Fe/MOR) were prepared and tested as catalysts in the catalytic wet peroxide oxidation process (CWPO). Their adsorption and catalytic effects on the removal of three isomeric cresols were systematically explored. Sufficient characterizations were carried out to illuminate the iron species dispersed on the catalysts' surface porous channels. Other properties of the catalysts such as the Si/Al ratio, crystalline structures, and morphologies were systematically studied. After loaded with iron, the catalysts maintained zeolite's framework, which possessed specific porous structures and surface areas. Interestingly, the Si/Al ratio seemed to be an important issue influencing the adsorption and catalytic degradation of cresols due to n-π interaction and the acceleration of HO• generation, respectively. The amount of framework-Fe and Fe³⁺Al-Si in Fe/ZSM-5-3 was the most, which was crucial for its better catalytic ability than the other Fe/ZSM-5 catalysts (71.19% for m-cresol conversion). In conclusion, the catalytic activities of all the Fe/zeolites followed the sequence: Fe/ZSM-5-3> Fe/ZSM-5-2> Fe/ZSM-5-1> Fe/MCM-22>Fe/MOR. For three cresols, m-cresol was more susceptible to the attack of HO• than p- and o-cresol because more positions of m-cresol could be easy to be approached by the oxidizing agent. Considering the mild reaction condition in this study, such as 30 °C, pH=4.0, and catalyst dosage=1.0 g/L, the Fe/ZSM-5-3 was a promising zeolite catalyst for the degradation of refractory contaminants in practical wastewater.

Persulfate enhanced photoelectrochemical oxidation of organic pollutants using self-doped TiO2nanotube arrays: Effect of operating parameters and water matrix

This study investigated the influence of adding peroxydisulfate (PDS) to a photoelectrocatalysis (PEC) system using self-doped TiO₂ nanotube arrays (bl-TNAs) for organic pollutant degradation. The addition of 1.0 mM PDS increased the bisphenol-A (BPA) removal efficiency of PEC (PEC/PDS) from 65.0% to 85.9% within 1 h. The enhancement could be attributed to the high formation yield of hydroxyl radicals (^·OH), increased charge separation, and assistance of the sulfate radicals (SO₄^·-). The PDS concentration and applied potential bias were influential operating parameters for the PEC/PDS system. In addition, the system exhibited a highly stable performance over a wide range of pH values and background inorganic and organic constituents, such as chloride ions, bicarbonate, and humic acid. Further, the degradation performance of the organic pollutant mixture, including BPA, 4-chlorophenol (4-CP), sulfamethoxazole (SMX), and carbamazepine (CBZ), was evaluated in 0.1 M (NH₄)₂SO₄ solution and real surface water. The degradation efficiency increased in the order of CBZ < SMX < 4-CP < BPA in the PEC and PEC/PDS systems with both water matrices. Compared with the PEC system, the PEC/PDS (1.0 mM) system showed a threefold higher pseudo first-order reaction rate constant for BPA among pollutant mixtures in surface water. This was attributed to enhanced ^·OH production and the selective nature of SO₄^·-. The pseudo first-order reaction rate constants of other pollutants, i.e., 4-CP, SMX, and CBZ increased ca. twofold in the PEC/PDS system. The results of this study showed that the PEC/PDS system with bl-TNAs is a viable technology for oxidative treatment.

Fate of environmental pollutants

This annual review covers the literature published in 2018 on topics related to the occurrence and fate of environmental pollutants in wastewater. Due to the vast amount of literature published on this topic, we have discussed only a portion of the quality research publications, due to the limitation of space. The abstract search was carried out using Web of Science, and the abstracts were selected based on their relevance. In a few cases, full-text articles were referred to understand new findings better. This review is divided into the following sections: antibiotic-resistant bacteria (ARBs) and antibiotic-resistant genes (ARGs), disinfection by-products (DBPs), drugs of abuse (DoAs), estrogens, heavy metals, microplastics, per- and polyfluoroalkyl compounds (PFAS), pesticides, and pharmaceuticals and personal care products (PPCPs), with the addition of two new classes of pollutants to previous years (DoAs and PFAS).

Emerging pollutants-Part II: Treatment

Recently, emerging pollutants (EPs) have been frequently detected in urban wastewater, surface water, drinking water, and other water bodies. EPs mainly usually include pharmaceuticals and personal care products, endocrine-disrupting chemicals, antibiotic resistance genes, persistent organic pollutants, disinfection by-products, and other industrial chemicals. The potential threat of EPs to ecosystems and human health has attracted worldwide attention. Therefore, how to treat EPs in various water bodies has become one of the research priorities. In this paper, some research results on treatment of EPs published in 2018 were summarized. PRACTITIONER POINTS: At present, more attention has been paid to emerging pollutants (EPs), including pharmaceuticals and personal care products (PPCPs), endocrine-disrupting chemicals (EDCs), antibiotic resistance genes, persistent organic pollutants, disinfection by-products, etc. Existing EPs disposal technologies mainly include: engineered wetlands and natural systems, biological treatment, physical and physicochemical separation, chemical oxidation, catalysis, etc. This paper reviews some research results on the treatment technologies of EPs published in 2018.

Removal Processes of Carbamazepine in Constructed Wetlands Treating Secondary Effluent: A Review

It is widely believed that constructed wetlands (CWs) own great potentiality as polishing wastewater treatment methods for removing carbamazepine (CBZ). Although the typical CBZ removal efficiencies in CWs are quite low, the CBZ removal performance could be improved to some extend by optimizing the CW design parameters. A comparison of current relevant studies indicates that horizontal sub-surface flow CWs (HSSF-CWs) and hybrid wetlands are attracting more interest for the treatment of CBZ wastewater. According to CBZ’s physicochemical properties, substrate adsorption (25.70–57.30%) and macrophyte uptake (22.30–51.00%) are the two main CBZ removal pathways in CWs. The CBZ removal efficiency of CWs employing light expanded clay aggregate (LECA) as a substrate could reach values higher than 90%, and the most favorable macrophyte species is Iris sibirica, which has shown the highest total CBZ assimilation capacity. Several methods for enhancement have been proposed to optimize CBZ removal in CWs, including development of hydraulic models for optimization of CW operation, introduction of extra new CBZ removal ways into CW through substrate modification, design of combined/integrated CW, etc.