Organic Micropollutants Research Articles

Trends in extraction techniques for the determination of organic micropollutants in liver tissues of vertebrates.

Determining organic micropollutants in liver samples of apex species is of foremost importance for biomonitoring studies, as it can provide evidence of environmental pollution and exposure of living organisms to chemicals. This review aims to provide a 4-year overview and summarize the trends in the extraction methodologies to determine both polar and non-polar organic micropollutants in liver samples from organisms of higher trophic levels. The dominant extraction techniques including ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), Soxhlet, and QuEChERS, as well as additional steps and/or modifications applied in the reviewed studies, are presented and critically discussed. The latest trends in these methods as well as a comparison between them considering elapsed time, robustness, cost, and environmental fingerprint are also provided.

A novel approach for immobilizing Ag/ZnO nanorods on a glass substrate: Application in solar light-driven degradation of micropollutants in water

One of the main challenges in applying photocatalysts for water treatment is the complex separation and recycling process. In this study, we developed highly stable, porous zinc oxide nanorods (ZnO NRs) immobilized on glass vials using a solvent exchange process (SEP) and hydrothermal calcination. Key parameters, including oleic acid concentration and hydrothermal growth time, were optimized to maximize the active surface area, significantly enhancing photodegradation performance. Under the best conditions, ZnO NRs-coated vials achieved nearly 100% degradation of sulfamethoxazole (SMX) in 10 h of simulated solar irradiation. Depositing silver nanoparticles on the surface of ZnO NRs (Ag/ZnO NRs) further improved performance, reducing degradation time to 4 h and increasing photocatalyst stability. The Ag/ZnO NRs-coated vials, optimized with an Ag precursor concentration of 0.05 M, also demonstrated high degradation rates (>99%) for eight organic micropollutants at environmentally relevant concentrations over multiple reuse cycles and with minimal metal leaching. This study presents an innovative, tunable method for immobilizing photocatalysts on glass substrates, offering high surface area, excellent photocatalytic activity, and mechanical properties, making it highly suitable for water treatment applications.

The first and cost-effective nano-biocomposite ZnPor/rGO/TiO2 as efficient UV photocatalysts for ethylparaben decomposition

Organic micropollutants are considered as dangerous wastes to aquatic environments, which threaten the life of living beings. The efficacious removal of these pollutants from surrounding aquatic ecosystems has been taken into consideration in water refinery technologies. In this study, a bio-nanocomposite was developed through a green approach involving self-assembly of reduced graphene oxide (rGO) with zinc [5,10,15,20-tetrakis(2,6-dichlorophenyl) porphyrin] complex (ZnPor) and TiO2 nanoparticles using reflux method. This organic/inorganic hybrid material was characterized using FE-SEM, XRD, EIS, RAMAN, and UV–Vis spectroscopy. The band-gap energies were found to range from 3.32 eV for GO to 2.35 eV for ZnPor/rGO/TiO2, indicating the composites behave as semiconductor materials. The photocatalytic activity was highest for the ZnPor/rGO/TiO2 composite based on 200 mL ZnPor addition during the synthesis process, achieving 98.1 % degradation of the model pollutant ethylparaben after only 20 min of UV treatment. The rGO facilitates electron-hole separation and transportation, while the ZnPor broadens the light absorption range and improves charge transfer. The TiO2 nanoparticles provide the primary photocatalytic sites. These synergistic effects enhanced the photocatalytic activity of the ZnPor/rGO/TiO2 system. This green-synthesized, eco-friendly, and highly efficient photocatalyst shows great promise for the removal of organic micropollutants from wastewater.

Effect of tunnel wash water treatment processes on trace elements, organic micropollutants, and biological effects

Tunnel wash water (TWW) contains high levels of trace elements and organic micropollutants, especially in the dissolved fraction. Discharge poses significant environmental risks. This field study aimed at improving conventional sedimentation treatment by addition of novel secondary treatments: bag filtration, ceramic microfiltration, or granular activated carbon (GAC) filtration. Removal of nine trace elements, 16 polycyclic aromatic hydrocarbons (PAHs), 38 per- and polyfluoroalkyl substances (PFASs), seven benzothiazoles (BTHs), seven benzotriazoles (BTRs), five bisphenols (BPs), and five benzophenones was investigated. Primary sedimentation significantly reduced particles and associated contaminants, achieving over 73 % average removal for trace elements, 65 % for PAHs, and 71 % for PFASs. Subsequent GAC removed over 70 % of dissolved Cr, Cu, Pb, and Zn and over 92 % of dissolved PFASs, BTHs, BTRs, and BPs, including several persistent, mobile and toxic compounds. Following GAC filtration, Cr, Ni, Pb, anthracene, fluoranthene, perfluorooctanesulfonic acid, and bisphenol-A were below environmental quality standards (EQS). GAC consistently reduced responses in in vitro bioassays with endpoints activation of the aryl hydrocarbon receptor, oxidative stress response, and neurotoxicity below effect-based trigger values for surface water. GAC filtration is thus recommended for future TWW treatment. Assessing water quality remains a challenging task due to lack of EQSs for many chemicals.

Removal of Organic Micropollutants and Microplastics via Ozonation Followed by Granular Activated Carbon Filtration

Discharge from Wastewater Treatment Plants (WWTPs) can result in the emission of organic micropollutants (OMPs) and microplastics (MPs) into the aquatic environment. To prevent this harmful release, a pilot plant consisting of an ozonation followed by a granular activated carbon (GAC) filter was operated at a WWTP in Germany, and its side-effects on the concentrations of nitrogen (N) and phosphorous (P) compounds were measured. Over 80% of OMPs and transformation products were removed during the operating time (around 6000 bed volumes) no matter the ozone dose (from around 0.1 to 0.5 mgO3/mgDOC), except for Diatrizoic acid, whose breakthrough appeared at 3500 BV. Formation of the oxidation by-product, NDMA, increased with higher ozone doses, but the concentration remained below 100 ng/L. Bromate was formed at a higher ozone dose (>0.4 mgO3/mgDOC) but at a low concentration—below 10 µg/L. The MP particles detected in the inflow (PE, SBR, PP, and PS) were effectively eliminated to a high degree, with a removal rate of at least 92%. Carbon parameters (COD, DOC, and SAC254) were removed further by the pilot plant, but to different extents. As expected, nitrate was formed during ozonation, while nitrite’s concentration decreased. Further, nitrite decreased and nitrate increased within the GAC filter, while ammonium was eliminated by at least 90%. Total P concentration decreased after the pilot, but the concentration of PO4-P increased.

Impact of emerging pollutants mixtures on marine and brackish phytoplankton: diatom Phaeodactylum tricornutum and cyanobacterium Microcystis aeruginosa

Pharmaceuticals and ionic liquids (ILs) are emerging as significant micropollutants with environmental presence and potential ecological impacts. The possible simultaneous occurrence of these two groups of pollutants in aquatic environments raises complex challenges due to their diverse chemical properties and potential for interactive effects. Given the documented widespread presence of pharmaceuticals and the emerging concerns about ILs, the study aims to evaluate the adverse effects of binary mixtures of imidazolium ionic liquid IM1-8C(CN)3 and two representatives of pharmaceuticals: antibiotic oxytetracycline (OXTC) and metabolite carbamazepine 10,11 epoxide (CBZ-E) on the brackish cyanobacterium Microcystis aeruginosa and the marine diatom Phaeodactylum tricornutum during chronic exposure experiments. A comprehensive approach was employed, incorporating various endpoints including oxidative stress, chlorophyll a fluorescence, detailed photoprotective and photosynthetic pigment profiles of target microorganisms to assess modes of action and identify the mixture effects of the selected substances.The observed alterations in pigment production affecting carotenoids synthesis in both selected species may be attributed to the differential impacts of these substances on the photosynthetic pathways and metabolic processes in the cyanobacterial and diatom cells. Changes in chlorophyll a fluorescence-specific parameters suggest impairment of the photosynthetic activity, particularly affecting the efficiency of photosystem II.The application of Concentration Addition (CA) and Independent Action (IA) mathematical models, complemented by the evaluation of Model Deviation Ratios (MDR), revealed predominantly antagonistic interactions within the studied mixtures. The findings of this study provide important insights into the effects of mixtures of organic micropollutants and their potential impact on environment including brackish and marine waters.

Dissolved organic matter-mediated adsorption behavior of benzophenones on functionalized covalent triazine frameworks

Adsorption is a highly efficacious technique for the remediation of organic micropollutants (OMPs). However, the presence of dissolved organic matter (DOM) frequently impedes adsorbent process, with insufficient attention given to this influence. This study systematically evaluates the adsorption performance of covalent triazine frameworks (CTFs) functionalized with electron-donating or electron-withdrawing groups for benzophenones (BPs). The adsorption capacities of SO3H-CTF, OH-CTF, and NH2-CTF for BPs were 512.11 μmol/g, 1356.27 μmol/g, and 1421.85 μmol/g, respectively. The adsorption mechanism is predominantly governed by π-π electron donor–acceptor (EDA) interactions, supplemented by hydrogen bonding, particularly in hydroxyl-containing BPs, with electrostatic interactions being relatively negligible. Functionalization with − OH and − NH2 groups increased the electron density in π-conjugated regions, enhancing BPs adsorption capacity, whereas − SO3H modification, due to its electron-withdrawing nature, acted as a π electron acceptor. Importantly, the mediating role of humic acid (HA) in the adsorption process was investigated. The CTF-BPs-HA ternary system can either inhibit/enhance π-π EDA interactions between π-electron donor/acceptor and BPs by adsorbing onto the CTF materials. The HA-mediated system primarily affects the film diffusion stage, with minimal impact on pore diffusion and inner surface adsorption. The oxygenated functional groups in HA slightly enhanced hydrogen bonding within the adsorption system, with negligible influence on electrostatic interactions. In the presence of HA, the overall adsorption capacity of SO3H-CTF decreased by 67.0 %, while that of OH-CTF and NH2-CTF increased by 120.9 % and 55.3 %, respectively. This study elucidates the electronic behavior modifications of functionalized CTFs during BPs adsorption and underscores the significant role of HA in interaction mechanisms, providing theoretical guidance for the design of advanced adsorbents to enhance pollutant removal efficiency.

A single-atom manganese nanozyme mediated membrane reactor for water decontamination

Single-atom nanozymes possess high catalytic activity and selectivity, and are emerging as advanced heterogeneous catalysts for environmental applications. Herein, we present the innovative synthesis and characterization of a single-atom manganese-doped carbon nitride (SA-Mn-CN) nanozyme, integrated into a polyvinylidene fluoride (PVDF) membrane for advanced water treatment applications. The SA-Mn-CN nanozyme demonstrates high peroxidase-like activity, efficiently catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and generating reactive oxygen species (ROS) for effective antibacterial action. Notably, the SA-Mn-CN/PVDF membrane showcases enhanced water permeability, superior antifouling properties, and ultra-fast degradation kinetics of organic pollutants. Mechanistic studies reveal that the nanozyme selectively generates Mn(IV)-oxo species via peroxymonosulfate (PMS) activation, crucial for the efficient oxidation processes. Our integrated membrane system effectively removes (within 1 min, > 92 % removal) a variety of organic micropollutants in continuous-flow operations, demonstrating excellent stability and minimal manganese leaching. Compared to conventional advanced oxidation process (AOPs)/membrane system, the SA-Mn-CN/PVDF/PMS system holds the advantages of high catalytic activity and selectivity for generation of reactive species, wide working pH range (pH3–11) and excellent stability and reusability under the backwashing conditions. The developed device-scale AOPs/membrane system was proven to be effective in bacterial inactivation and pollutants degradation, verifying the vast application potential of the SA-Mn-CN/PVDF membrane for practical water decontamination. This work pioneers the development of enzyme-mimicking nanozyme membranes, offering a sustainable and high-performance solution for wastewater treatment, and sets a new benchmark for the design of nanozyme-based catalytic membranes in environmental applications.

Biodegradation of organic micropollutants by anoxic denitrification: Roles of extracellular polymeric substance adsorption, enzyme catalysis, and reactive oxygen species oxidation

The control of organic micropollutants (OMPs) in water environments have received significant attention. Denitrification was reported to exhibit good efficiency to remove OMPs, and the mechanisms involved in are too intricate to be well illustrated. In this study, we selected nitrobenzene [NB] and bisphenol A [BPA] as model pollutants and aimed to unravel the mechanisms of Paracoccus Denitrificans in the removal of OMPs, with a specific emphasis on aerobic behavior during denitrification processes. We demonstrated the formation of extracellular superoxide radicals, i.e., extracellular •O2-, using a chemiluminescence probe and found that extracellular polymeric substance adsorption, extracellular •O2-, and microbial assimilation contributed approximately 40 %, 10 %, and 50 % to OMPs removal, respectively. Transcriptome analysis further revealed the high expression and enrichment of several pathways, such as drug metabolism-other enzymes, of which a typical aerobic enzyme of polyphenol oxidase [PPO] participates in the degradation of NB and BPA. Importantly, all the immediate products showed a significant decrease in toxicity during the aerobic activity-related OMPs degradation process based on the proposed degradation pathways. This study demonstrates the formation of extracellular •O2- and the mechanisms of extracellular •O2-- and PPO-mediated OMPs biodegradation, and offers new insights into OMPs control in widely-used denitrification treatment processes.

Reactive Oxygen Species Generated in Situ During Carbamazepine Photodegradation at 222 nm Far-UVC: Unexpected Role of H2O Molecules.

When 222 nm far-UVC is used to drive AOPs, photolysis emerges as a critical pathway for the degradation of numerous organic micropollutants (OMPs). However, the photodegradation mechanisms of the asymmetrically polarized OMPs at 222 nm remain unclear, potentially posing a knowledge barrier to the applications of far-UVC. This study selected carbamazepine (CBZ), a prevalent aquatic antiepileptic drug that degrades negligibly at 254 nm, to investigate its photodegradation mechanisms at 222 nm. Accelerated CBZ treatment by 222 nm far-UVC was mainly attributed to in situ ROS generation via self-sensitized photodegradation of CBZ. By quenching experiments and EPR tests, •OH radicals were identified as the major contributor to the CBZ photodegradation, whereas O2•- played a minor role. By deoxygenation and solvent exchange experiments, the H2O molecules were demonstrated to play a crucial role in deactivating the excited singlet state of CBZ (1CBZ*) at 222 nm: generating •OH radicals via electron transfer interactions with 1CBZ*. In addition, 1CBZ* could also undergo a photoionization process. The transformation products and pathways of CBZ at 222 nm were proposed, and the toxicities of CBZ's products were predicted. These findings provide valuable insights into OMPs' photolysis with 222 nm far-UVC, revealing more mechanistic details for far-UVC-driven systems.

Constructing porous aromatic frameworks from natural products for organic pollutant capture

Organic micropollutants in water have raised increasing concerns about aquatic ecosystems and human health. Porous aromatic frameworks (PAFs) with highly porosity and good stability are widely used as sewage treatment agents. However, most of the PAFs are constructed by laboratory-synthesized building units, which are much expensive and increase the total cost of PAFs. At the same time, it is also a potential threaten that these synthetic compounds may affect human health and environmental safety. These shortcomings limit the environmental application of PAF materials. In this work, a route that synthesizing a series of PAFs was developed by using polyphenolic natural products as building units. As a prototype, PAF-274 was constructed by resveratrol to give a permanently porous material, and used for extracting bisphenol A from water. PAF-274 possessed specific surface area of 242 m2/g, and dual pore size at 1.6 and 2.7 nm. The maximum adsorption capacity for bisphenol A was 897 mg/g, which exceeded many other adsorbents and retained the high removal efficiency after 10 cycles. A wide range of non-toxic and harmless natural products can be used to construct porous materials. This synthetic method of introducing natural products broadens the selection of building units for PAFs and opens a new way for the design of functional porous materials.

Integrated spectral based monitoring, optimization and control of the combined ozonation and powdered activated carbon adsorption process to remove organic micropollutants from secondary effluent

In this study, an innovative approach for the integrated monitoring, optimization and control of the combined ozonation (O3) and powdered activated carbon (PAC) adsorption process is introduced making use of spectral surrogates (UVA254 and EEM-PARAFAC components). The combined O3-PAC process is designed to remove organic micropollutants (µP) from secondary effluent. Therefore, the removal of 6 µP with varying ozone reactivity was systematically studied in both O3 and PAC as stand-alone systems and in the combined O3-PAC system. For the latter, adsorption experiments were performed with µP spiked into ozonated secondary effluent (sequential system) and with µP spiked into the initial secondary effluent before ozonation (integrated system). In accordance with Swiss standards, the goal was to achieve 80% atrazine removal (as a model O3 recalcitrant compound) at optimized O3 and PAC doses. An ozone dose ranging from 0.45 to 0.65 mg O3/mg DOC was more cost-effective in promoting subsequent PAC adsorption (less than 40%), particularly at low PAC doses (1-2 mg PAC/mg (initial (DOC))). The classical ideal adsorbed solution theory (IAST) model could not be used to predict the subsequent PAC dose after ozonation in the integrated system. Therefore, correlation models were established between (i) the reduction of spectral surrogates during both O3 and PAC dosing and µP removal, (ii) the reduction of spectral surrogates during ozonation and the related PAC dose of the subsequent adsorption process and (iii) between the reduction of spectral surrogates during ozonation and the integrated process. Based on these correlation models, an online spectral control strategy was developed and implemented. Finally, the optimal dosing strategy for 80% atrazine removal was determined as 0.5 mg O3/mg DOC and 1.4 mg PAC/mg (initial) DOC.

Symmetric and asymmetric ceramic-supported polyelectrolyte multilayer nanofiltration membranes

Polyelectrolyte multilayer based nanofiltration membranes can remove organic micropollutants from water. Such polyelectrolyte multilayer membranes (PEMMs) are often assembled on polymeric supports, but less research focuses on inorganic (ceramic) supports. In this work, we assembled symmetric and asymmetric, coatings of poly(allylamine (PAH) and poly(styrene sulfonate) (PSS) on ceramic supports. Symmetric membranes are assembled with the same salt concentration in the coating solution for each layer. Asymmetric membranes use very permeable layers (high salt concentration in coating solution) as base layers and dense top layers with lower permeability (low salt concentration in coating solution) as filtration layers. By reversing the coating order – first salt-free and after that high salt concentration, we obtained reverse asymmetric membranes. They consistently outperformed the symmetric and standard asymmetric design in removing organic micropollutants, reaching an average retention of 85 ± 13 % compared to 77 ± 14 % for the standard asymmetric membranes. We attribute this higher retention to a more efficient pore overcoating for the reverse asymmetric membranes. This work demonstrates that ceramic supports combined with reverse asymmetric PEMMs can be efficiently used for micropollutant removal from water.

Melamine enhancing Cu-Fenton reaction for degradation of anthracyclines

Melamine (MA) enhanced Cu-Fenton process was developed for the degradation of anthracyclines. Taking daunorubicin (DNR) degradation as an example, we found that the initial first-order apparent constant of Cu2+/MA/H2O2 system with a molar ratio of 1:8 for Cu2+:MA was 5.2 times higher than that of conventional Cu2+/H2O2 system. The in-situ reductive coordination between Cu2+ and MA facilitated the generation and stabilization of Cu+ species, thereby accelerating the rate-limiting step of Cu2+/Cu+ conversion and maintaining high levels of Cu+ during the degradation process. Moreover, pre-synthesized Cu+-MA complexes (e.g., CM-250) further enhanced the efficiency of the Cu-Fenton reaction by increasing both the Cu+ proportion and MA chelation. The apparent activation energy for DNR degradation in CM-250 mediated Fenton reaction (15.9 kJ mol−1) was lower than that in systems involving Cu2+/MA (41.2 kJ mol−1) and Cu2+ (65.6 kJ mol−1). Enhanced generation of various reactive oxygen species (·OH,·O2-, and 1O2) was confirmed, with 1O2 playing a dominant role, significantly improving both degradation rate and mineralization degree for DNR. MA-enhanced Cu-Fenton process also offers a convenient alternative to effectively remove other anthracyclines and organic micropollutants, holding great promise for advancing advanced oxidation processes as well as practical large-scale degradation applications targeting multiple pollutants.

A machine learning based framework to tailor properties of nanofiltration and reverse osmosis membranes for targeted removal of organic micropollutants

Nanofiltration (NF) and reverse osmosis (RO) membranes play an increasingly important role in the removal of organic micropollutants (OMPs), which puts higher demands on the customization of membranes suitable for OMPs removal based on the rejection mechanisms. Here, the pathways of OMPs-targeted optimization for membranes were constructed by using machine learning (ML) to capture the correlations between OMPs removal efficiency with properties of membranes and OMPs. Through expertise assistance and rigorous modeling methodology, an accurate and robust Extreme Gradient Boosting (XGBoost) model was established, which could well recognize the dominant rejection mechanisms of OMPs (i.e., the size exclusion effect and electrostatic interactions). An exemplary application to another dataset of several high-risk OMPs showed how the optimized model could be used to estimate the overall efficiency of OMPs risk control and, more importantly, to provide quantitative guidance on membrane properties for specific removal targets. The satisfying prediction results demonstrated the good generalization of the ML model and consequently its ability to sensitively define the ideal membrane properties for the targeted removal of these (and any other concerned) OMPs. This study provides a feasible and universal ML-based framework to achieve the tailored selection and design of NF/RO membranes for OMPs risk control.

Removal of persistent and mobile organic micropollutants from drinking water utilizing a synthesized waste-derived adsorbent

Persistent and mobile (PM) substances refer to a wide range of organic micropollutants (OMPs) with high persistence and mobility in water. So far, only a few methods have been explored for the removal of PM substances from drinking water. In this work, a new adsorbent based on spent coffee grounds and aluminum waste was synthesized and utilized to remove 25 OMPs, including 22 PM substances, from drinking water. Different characterization methods, including powder X-ray diffraction (XRD), analyses according to Brunauer−Emmett−Teller (BET), field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS), were applied to describe the adsorbent's textural and structural characteristics. The results revealed that the adsorbent is highly effective in removing OMPs. Common OMPs (i.e. carbamazepine, sulfamethoxazole and diclofenac) were completely removed from drinking water. Also, many of the PM substances were removed by more than 80% using an adsorbent dosage of 0.1 g/L. A strong relation between abatement of ultraviolet light absorbance at 254 nm (UV254) and OMP removal was observed. Therefore, UV254 abatement is a useful surrogate for a quick estimation of OMP removals.

A new approach on the management of landfill leachate reverse osmosis concentrate: Solar distillation coupled with struvite recovery and biological treatment

The management of reverse osmosis (RO) concentrate remains a challenging task for operators of Landfill Leachates Treatment Plants. In this article we suggest an integrated treatment scheme for RO concentrate that combines solar distillation, struvite precipitation to reduce ammonia content of the distillate and biological treatment of the supernatant either with mixed cultures of bacteria or with microalgae. Experiments in a pilot-scale solar still, equipped with underfloor heating system, showed that the production rate of the distillate ranged up to 3.17 L/d m2. The distillate was characterized by elevated average concentrations of ammonium nitrogen; 2028 mg/L and 1358 mg/L in the two experiments conducted, respectively. A decreasing trend on concentrations of NH4+-N was noticed during these experiments, while the opposite was observed for COD. Struvite recovery experiments showed that the optimum Mg:NH4:PO3 ratio was that of 2:1:5.8. Under these conditions, the NH4+-N removal reached 88%. Further treatment of the process supernatant into a 4-L hybrid sequencing batch reactor with biocarriers and activated sludge achieved NH4+-N removal higher than 98% in Phases C and D, where 450 and 600 mL of supernatant were added, respectively. Similar removal was also observed in a 2-L bioreactor with microalgae Chlorella sorokiniana when 150 mL of struvite supernatant were added (Phase B) while further increase of the amount of added supernatant to 200 mL resulted to a sharp stop of NH4+-N consumption (Phase C). Calculations for a landfill serving 20,000 inhabitants and a daily RO concentrate production of 6 m3/d showed that the required area for the construction of the solar still was 1893 m2 and the volumes of the hybrid and the microalgae reactor were 54 m3 and 60 m3, respectively. The recovered solid material of struvite process, after characterization for heavy metals and organic micropollutants, could be reused to the fertilizers industry.

Porous calix[4]pyrrole-based polymers with high surface area for efficient removal of polar organic micropollutants from water

Herein, effort was made to construct innovative adsorbent for the removal of polar organic micropollutants (OMPs) from water. Tetra-meso resorcinol-functionalized calix[4]pyrrole (CP) featured with endo-functionalized attribute and polyphenol hydroxyl structure was crosslinked by π-electron-rich 4,4′-bis(chloromethyl)biphenyl (BCMBP) through Friedel-Crafts reaction to generate porous calix[4]pyrrole-based polymers (PCPPs) with high surface area. The porosity of the PCPPs could be tuned by adjusting the molar ratio of hydrophilic CP to hydrophobic BCMBP, and diversified binding sites were integrated together. Based on adsorption kinetics and isotherm studies, PCPP(1–16) showed rapid adsorption rate and high removal efficiency (RE) as well as advanced adsorption capacity. The REs towards the tested polar OMPs by PCPP(1–16) were all above 95% in 30 min. Compared with granular activated carbon (GAC), the rate constant of pseudo-second-order model (k2) and adsorption capacity upon PCPP(1–16) were 8–230 times and 1.3–3.1 times greater than those by GAC. Adsorption mechanism studies confirmed the presence of multiple interactions and thermodynamic investigation revealed the spontaneous and physical adsorption nature. Besides, PCPP(1–16) showed excellent adsorption performance in real water samples at environmental levels and exhibited advanced absorption ability in flow-through mode. Accompanied by facile regeneration under eluting with methanol and cost-effective preparation, PCPP(1–16) demonstrated great potential as promising adsorbent for water treatment.

Peracetic acid activation by chitosan-derived nitrogen-doped carbon spheres loaded with zero-valent copper for efficient sulfamethazine degradation in groundwater

Herein, chitosan-derived nitrogen-doped carbon spheres supported zero-valent copper (Cu@NCs) was prepared for the activation of peracetic acid (PAA) to degrade sulfamethazine (SMT) in groundwater under neutral condition. Several key influencing factors such as pyrolysis temperature, PAA concentration, Cu@NCs dosage, initial pH, inorganic ions and humic acid (HA) were investigated. The findings displayed that the Cu@NCs/PAA system could effectively degrade 94.5 % SMT (10.0 μM) in simulated groundwater in 30 min at low concentrations of PAA (50.0 μM), and the optimum pH was 7. Radical quenching experiments and EPR examinations verified that radicals (•OH, R-O• and O2•−) and non-radical 1O2 were produced in the Cu@NCs/PAA system, with R-O• and 1O2 being the primary contributors to the elimination of SMT. Zero-valent copper continuously transfers electrons through carbon spheres (electron shuttles) to produce Cu+, effectively activating the PAA to produce the active substance, accompanied by the production of Cu2+. Subsequently, Cu0 could convert the produced Cu2+ to Cu+ and then participate in the activation of the PAA. Direct electron transfer from SMT to PAA was enhanced by catalyst-mediated processes, which benefited from the function of carbon spheres in electron transport. Through cooperative efforts across radical and non-radical pathways, SMT was rapidly removed with trace amounts of PAA. In addition, inorganic ions (Cl−, SO42−, and HCO3−) had almost no effect on the Cu@NCs/PAA system, while HA had a certain degree of inhibition on the degradation of SMT. Furthermore, the Cu@NCs/PAA system displayed good reusability and easy recyclability. This work offered fresh perspectives and ideas on the removal of organic micropollutants using copper-based materials in the field of PAA-based AOPs, which promises to be an antibiotic-contaminated groundwater remediation solution.

COFs functionalized self-cleaning loose nanofiltration membranes for efficient dye/salt separation

In spite of the fact that loose nanofiltration membrane (LNFM) technology has certified inspiring prospects in the remediation of dyestuff-comprising wastewater, omnipresent membrane fouling deteriorates its separation competence and hinders its practical application. Herein, a neoteric LNFM with finely tuned anti-fouling and self-cleaning properties was manufactured via the reformative phase inversion procedure integrated with the correctional interfacial polymerization process. By altering the casting solution (i.e., adding nano additives) and coagulation bath (i.e., applying melamine aqueous solution rather than pure water) recipes, the porphyrin-based covalent organic framework (COF-366) and melamine monomers were introduced into the polymeric matrix ingeniously in one step, participating the subsequent interfacial polymerization reaction straightly. The COF-366 with photocatalytic degradation performance and hydrophilicity bestows the resultant LNFM with superior decomposing capacity for organic micro-pollutants under visible light irradiation and better operation durability. Moreover, this substrate-confined amine diffusion combined with the high polarity of melamine enables the formation of a thinner nanofilm for easy mass transport. The best-performing LNFM invented in this work exhibited a high water permeance up to 65 L m−2 h−1 bar−1, excellent dye retention (95.7 % against methyl blue), and salt/dye discrimination (27.1 for methyl blue and Na2SO4 selectivity) abilities. Eventually, the membrane could recover to original separation efficacy after the cyclic degradation testing. Overall, this work demonstrates an extensive perspective to pioneer an advanced self-cleaning membrane for dye/salt fractionation.