Performance and mechanisms for tetrabromobisphenol A efficient degradation in a novel homogeneous advanced treatment based on S2O42- activated by Fe3

Antagonistic effects of polystyrene microplastics and tetracycline on Chlorella pyrenoidosa as revealed by infrared spectroscopy coupled with multivariate analysis

Microplastics and antibiotics are typical emerging contaminants in the environment, posing considerable risks to the ecosystem and human health. Previous studies have reported synergistic or antagonistic effects in the presence of both microplastics and antibiotics, destructing cell membrane, inhibiting photosynthetic capability, and inducing antioxidant enzyme activity. However, there is still lack of comprehensive understanding of the mechanisms. This study applied infrared biospectroscopy and multivariate analysis to explore the physiological and biochemical toxicity of polystyrene microplastics and tetracycline co-exposure on Chlorella pyrenoidosa. Either tetracycline or polystyrene microplastics alone posed toxicities on C. pyrenoidosa, mainly due to changes in photosynthetic content, cell membrane permeability, MDA content and antioxidant enzyme activity. Co-exposure of tetracycline and polystyrene microplastics exhibited an antagonistic effect. Infrared spectroscopy coupled with multivariate analysis isolated the discriminating biomarkers representing different toxicity mechanisms, successfully explaining the mechanism of antagonism as reducing ROS production, regulating antioxidant enzyme activity, stabilizing cell membrane, and interfering with signaling and protein synthesis. A random forest model was developed and satisfactorily recognized the toxicity of individual toxins (accuracy of 98.75 %, sensitivity of 99.22 % and specificity of 99.65 %). It also rapidly apportioned toxicity origin and evidenced that tetracycline contributed to the majority of binary toxicities. This study provided scientific guidance and a theoretical basis for assessing and apportioning the binary toxicities of emerging contaminants.

Insight into homogeneous activation of sodium hypochlorite by dithionite coupled with dissolved oxygen (DO@NaClO/DTN) for carbamazepine degradation

Emerging contaminants (ECs) including carbamazepine (CBZ) in aquatic systems pose non-target risks to wildlife. We introduce an innovative advanced oxidation process (AOP) utilizing sodium hypochlorite (NaClO), which achieved 45.3 % degradation and mineralization of CBZ within 60 mins. Natural saturated state dissolved oxygen (DO, ∼7.5 mg·L-1) played a crucial role in synergistically activating NaClO with dithionite (DTN) without extra energy consumption. In DO@NaClO/DTN system, scavenging tests and electron spin resonance (ESR) analysis confirmed that ·OH and Cl· were dominant for CBZ degradation. The critical DO was responsible for the direct simultaneous production of ·OH and Cl·, confirmed by the greater thermodynamic data ΔG from density functional theory (DFT) calculation. These reactive species participate in subsequent transformations of SO4·-, O2·-, and 1O2. Preferential hydroxylation of CBZ first occurred due to the attacking at the reactive sites of C(21) and C(22) atoms. LC-MS/MS detection and DFT theoretical calculations also verified the sequent mechanisms of Meinwald rearrangement, deamidation and hydroxylation, cyclized hydroxylated and dehydrated with the decreasing ΔG. Ubiquitous Cl- accelerated CBZ degradation remarkably, regardless of its concentration. The significant enhancement of Cl- for CBZ degradation in DO@NaClO/DTN system suggest its promising application for ECs degradation in high-chloride seawater including offshore wastewater and tailwater in mariculture.

Synergistically enhanced heterogeneous activation of dissolved oxygen for aqueous carbamazepine degradation over S(III) coupled with siderite

The wide occurrence of emerging contaminants (ECs) was drawing more attention due to the potential hazard and threat on human and environment. Carbamazepine (CBZ) is a widely prescribed medication that has garnered considerable research interest with the exposures exceeding the environmental carrying capacity. We have established the innovative heterogeneous advanced oxidation process (AOPs) based on the activated dissolved oxygen (DO) coupled with S(III) and natural iron ore (siderite). In S(III)/O2/siderite system, we investigated the degradation efficiency, reactive species generation mechanism, and degradation pathway of CBZ. CBZ degradation and mineralization rate were 90% above and ∼15% with the reaction time of 40 min. The degradation of CBZ conformed to a pseudo-first-order kinetic model, with an activation energy determination of 76.36 kJ/mol. The optimal initial solution pH was the weak acid condition (pH = 4-6) for CBZ degradation. Moreover, the inhibition effects of coexisting substance including Cl-, HCO3-, and natural organic matter (NOM) on CBZ removal were observed, while the coexisted SO42- exhibited no significant influence. In addition, the reactive species generated in S(III)/O2/siderite system were predominantly identified as sulfate radical (SO4∙-) and hydroxyl radical (∙OH). The crucial intermediate complexes, Fe(III)S(IV)O3(+) and Fe(II)HS(IV)O3(+), was proposed to form in the initial stages of the reaction, which upon decomposition, yielded SO4∙- along with other reactive species. The degradation pathway of CBZ primarily involved deamination, oxidative ring-opening, hydroxylation, decarboxylation, and ketone degradation processes. This work provides the effective approach for the CBZ degradation with the mild reaction conditions and the sustainable technology for ECs treatment and control.

Improved permeability in ceramsite@powdered activated carbon (PAC)-MnOx coupled gravity-driven ceramic membrane (GDCM) for manganese and ammonia nitrogen removal with intermittent short-term vertical aeration

In our work, a gravity-driven ceramic membrane bioreactor (GDCMBR) was developed to remove Mn2+ and NH3-N simultaneously through the birnessite water purification layer in-situ construction on the ceramic membrane due to chemical pre-oxidation (powdered activated carbon (PAC)-MnOx). Considering the trade-off of biofouling and water production, the daily intermittent short-term vertical aeration mode was involving to balance this contradiction with the excellent water purification and improved membrane permeability. And the GDCMBR permeability of operation flux was improved for 5-7 LHM with intermittent short-term vertical aeration. Furthermore, only ∼7 % irreversible membrane resistance (Rir) also confirmed the improved membrane permeability with intermittent short-term vertical aeration. And some manganese oxidizing bacteria (MnOB) and ammonia oxidizing bacteria (AOB) species at genus level were identified during long-term operation with the contact circulating flowing raw water, resulting in the better Mn2+ and NH3-N removal efficiency. Additionally, the nano-flower-like birnessite water purification layer was verified in ceramsite@PAC-MnOx coupled GDCMBR, which evolute into a porous flake-like structure with the increasing intermittent short-term aeration duration. Therefore, the sustainable and effective intermittent short-term aeration mode in ceramsite@PAC-MnOx coupled GDCMBR could improve the membrane permeability with the satisfactory groundwater purification efficiency, as well as providing an energy-efficient strategy for membrane technologies applications in water supply safety.

Optimizing soil tetrabromobisphenol A remediation through iron-based activation of persulfate: A comparative analysis of homogeneous and heterogeneous systems

Tetrabromobisphenol A (TBBPA) that widely exists in soil and poses a potential threat to ecological environment urgently needs economically efficient remediation techniques. This study utilized both homogeneous Fe2⁺ solution and heterogeneous iron-based nanomaterials (chemically synthesized nano zero-valence iron (nZVI) and green-synthesized iron nanoparticles (G-Fe NPs)) to activate persulfate (PS) and assess their efficacy in degrading TBBPA in soil. The results demonstrate the superior performance of heterogeneous catalytic systems (WG-Fe NPs/PS (82.07%) and WnZVI/PS (78.32%)) over homogeneous catalytic system (WFe2+/PS (71.69%)), In addition, G-Fe NPs and nZVI effectively controlled the slow release of Fe2+. The optimization analysis using response surface methodology (RSM) reveal the remarkable significance of the experimental model based on the box-behnken design. RSM show that G-Fe NPs/PS exhibited optimal process parameters and predicted the maximum soil TBBPA degradation efficiency reaching 98.77%. The results of density functional theory calculations suggest that C-Br are the primary targets for electrophilic substitution reactions. Based on the f0 value and △G, the degradation pathway of TBBPA is inferred to involve a sequential debromination process, followed by the cleavage of intermediate carbon-carbon bonds and subsequent oxidation reactions. Hence, G-Fe NPs/PS not only facilitate waste resource utilization but also hold significant application potential.

Structural Modification Strategies, Interfacial Charge-Carrier Dynamics, and Solar Energy Conversion Applications of Organic-Inorganic Halide Perovskite Photocatalysts

Over the past few decades, organic-inorganic halide perovskites (OIHPs) as novel photocatalyst materials have attracted intensive attention for an impressive variety of photocatalytic applications due to their excellent photophysical (chemical) properties. Regarding practical application and future commercialization, the air-water stability and photocatalytic performance of OIHPs need to be further improved. Accordingly, studying modification strategies and interfacial interaction mechanisms is crucial. In this review, the current progress in the development and photocatalytic fundamentals of OIHPs is summarized. Furthermore, the structural modification strategies of OIHPs, including dimensionality control, heterojunction design, encapsulation techniques, and so on for the enhancement of charge-carrier transfer and the enlargement of long-term stability, are elucidated. Subsequently, the interfacial mechanisms and charge-carrier dynamics of OIHPs during the photocatalytic process are systematically specified and classified via diverse photophysical and electrochemical characterization methods, such as time-resolved photoluminescence measurements, ultrafast transient absorption spectroscopy, electrochemical impedance spectroscopy measurements, transient photocurrent densities, and so forth. Eventually, various photocatalytic applications of OIHPs, including hydrogen evolution, CO2 reduction, pollutant degradation, and photocatalytic conversion of organic matter.

Kinetic and isotherm of competitive adsorption cadmium and lead onto Saccharomyces cerevisiae autoclaved cells

Heavy metal pollution has been regarded as a significant public health hazard during the industrialization, which also have exhibited various types of toxicological manifestations. Moreover, due to the high cost and toxic by-products, some conventional remediation methods were limited to heavy metals pollution control. In this work, autoclaved Saccharomyces cerevisiae was used as a biosorbent for the removal of Cd2+ and Pb2+ from single and binary ions aqueous solution system. The kinetics and isotherm of Cd2+ and Pb2+ were studied in different ion systems. The results showed that the competitive adsorption ability of S. cerevisiae to Pb2+ was stronger than that to Cd2+ in binary ions solution. To all the single ion solution of Cd2+ or Pb2+ and binary ions solution of Cd2+-Pb2+, there always existed that the adsorption of metal ions on S. cerevisiae fitted well with pseudo-second-order kinetic model and Langmuir isotherms model. The adsorption quantity qt in different solutions followed the sequence as qt (Cd2+-Pb2+) > qt (Pb2+-single) > qt (Pb2+-binary) > qt (Cd2+-single) > qt (Cd2+-binary). The autoclaved S. cerevisiae used in this research was one kind of rapid and favourable biosorbent for Pb2+ and Cd2+. In Pb2+ and Cd2+-containing solutions, sites competition and jointed toxicity of Pb2+ and Cd2+ on S. cerevisiae cells were the key to the total adsorption effect, and further researches were necessary in the next work. Thus, the current research presented that the autoclaved S. cerevisiae could be applied as an effective biosorbent for heavy metal adsorption from water environment and the design of eco-friendly technologies for the treatment of waste liquor.

Overlooked impacts of natural organic matter conversion in a Fe(II)-induced peroxymonosulfate activation system for river water remediation

The peroxymonosulfate (PMS) process may be hindered severely due to natural organic matter (NOM) conversion in the treatment of emerging pollutants from river water, becoming a critical engineering and technical issue. In this study, a Fe(II)-induced river water (RW)/PMS catalytic system was constructed for investigating molecular transformation of NOM and related influence mechanism to sulfamethoxazole (SMX) degradation. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) analysis indicated that NOM molecules containing no more than one heteroatom in river may be attacked by hydroxyl radicals (OH) and then polymerized, converting into molecules with two or three heteroatoms during PMS oxidation. Based on the correlation analysis, CHONP-NOM, CHOSP-NOM and CHONSP-NOM showed a significant inhibition against SMX degradation, while CHONS-NOM exhibited a moderate inhibitory effect. Besides, more condensed aromatic structures, carbohydrates and tannins were generated via reactive species (OH and sulfate radicals (SO₄^-)) oxidation, radical addition and polymerization reactions. Notably, condensed aromatic structures, carbohydrates and tannins presented weak, modest and strong inhibition to SMX degradation, respectively. Based on the current results, the inhibition of target pollutants degradation would be mitigated via regulation of NOM molecules in a Fe(II)-induced PMS activation system, providing valuable information to reduce NOM impact. In addition, this study paves the way to achieve efficient removal of emerging pollutants from river water.