Visible-light-assisted persulfate activation by SnS2/MIL-88B(Fe) Z-scheme heterojunction for enhanced degradation of ibuprofen

Dual chemical bonding construction of electrochemical peptide sensor based on GDY/MOFs(Fe) composite for ultra-low determination of prostate-specific antigen

A novel "double chemical bonding" electrochemical peptide biosensor 2FcP-GA-GDY(Fe)@NMIL-B was developed for highly selective, ultrasensitive, and ultrastable identification of prostate-specific antigen (PSA). The C-Fe-O chemical bond linking Fe-Graphdiyne (Fe-GDY) with NH2-MIL88B(Fe) (NMIL88B) as the first chemical bonding of electrode carrier Fe-GDY@NH2-MIL88B(Fe) (GDY(Fe)@NMIL) significantly accelerates electron transport. With glutaraldehyde (GA) as a crosslinking agent, the Schiff-base -NC- formed by GDY(Fe)@NMIL nanocomposites links the two Fc molecules labeled peptides (2FcP) as the second chemical bonding, facilitating high-density attachment of peptides to the electrode carrier in a firm manner. When the PSA analyte is introduced to identify and cleave the specific peptide, the release of ferrocene from its head leads to a decrease in the electrical signal, enabling sensitive detection. The prepared sensing platform exhibits exceptional analytical performance for PSA with an extended linear response range from 10 fg mL-1 to 50 ng mL-1. Additionally, the detection limit has been significantly reduced to an ultra-low level of only 0.94 fg mL-1, surpassing those reported in most literature by several orders of magnitude. Moreover, the 2FcP-GA-GDY(Fe)@NMIL-B sensor has excellent selectivity and stability while also showcasing great potential for practical application of PSA detection in human serum using the standard addition method.

Advances and challenges in the removal of organic pollutants via sulfate radical-based advanced oxidation processes by Fe-based metal-organic frameworks: A review

Organic contaminants, notorious for their complexity and resistance to degradation, are prevalent in aquatic environments, posing severe threats to ecosystems. Sulfate radical-based advanced oxidation processes (SR-AOPs), known for their stability and high effectiveness, have become a common choice for treating organic wastewater. Metal-organic framework materials (MOFs) have garnered substantial attention due to their facile chemical manipulation, unique structural configurations, and other favorable properties. Therefore, this article critically reviews recent advances in research involving the utilization of Fe-based MOFs (Fe-MOFs) and their derivatives in SR-AOPs. Specifically, it highlights the manipulation of influencing factors within the system to enhance the degradation of organic pollutants. The mechanisms and applications underlying the degradation of organic pollutants in the SR-AOPs system are also elucidated.

Quasi-type-II Cu-In-Zn-S/Ni-MOF heterostructure with prolonged carrier lifetime for photocatalytic hydrogen production

Visible-driven photocatalytic hydrogen production using narrow-bandgap semiconductors has great potential for clean energy development. However, the widespread use of these semiconductors is limited due to problems such as severe charge recombination and slow surface reactions. Herein, a quasi-type-II heterostructure was constructed by combining bifunctional Ni-based metal-organic framework (Ni-MOF) nanosheets with BDC (1,4-benzenedicarboxylic acid) linker coupled with Cu-In-Zn-S quantum dots (CIZS QDs). This heterostructure exhibited a prolonged charge carrier lifetime and abundant active sites, leading to significantly improved hydrogen production rate. The optimized rate achieved by the CIZS/Ni-MOF heterostructure was 2642 μmol g-1 h-1, which is 5.28 times higher than that of the CIZS QDs. This improved performance can be attributed to the quasi-type-II band alignment between the CIZS QDs and Ni-MOF, which facilitates effective delocalization of the photogenerated electrons within the system. Additional photoelectrochemical tests confirmed the well-maintained photoluminescence and prolonged charge carrier lifetime of the CIZS/Ni-MOF heterostructure. This study provides valuable insights into the use of multifunctional MOFs in the development of highly efficient composite photocatalysts, extending beyond their role in light harvesting and charge separation.

Constructing a Z-Scheme Co3O4/BiOBr Heterojunction to Enhance Photocatalytic Peroxydisulfate Oxidation of High-Concentration Rhodamine B: Mechanism, Degradation Pathways, and Toxicological Evaluations

Photocatalytic coupling technologies have emerged as popular strategies to increase the treatment efficiency of dye-containing wastewater. Herein, the Z-scheme Co3O4/BiOBr heterojunction (Z-CBH) was constructed and developed as a photocatalytic peroxydisulfate (PDS) activator for the degradation of high-concentration Rhodamine B (RhB). Multiple testing techniques were employed to confirm the formation of Z-CBHs. When 0.1 g·L-1 of Z-CBH20 and 1.0 mmol·L-1 of PDS were added simultaneously under simulated sunlight irradiation, the RhB degradation efficiency could approach 91.3%. Its reaction rate constant (0.01231 min-1) was much beyond the sum of those in the Z-CBH20/light system (0.00436 min-1) and the PDS/light system (0.0062 min-1). h+, •OH, •O2-, SO4•-, and 1O2 were detected as the dominant reactive species for RhB degradation. The potential mechanism of photocatalytic PDS oxidation was proposed. The possible intermediates were determined by high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry assisted with density functional theory and Fukui theory. The possible degradation pathways of RhB degradation were put forward. The toxicological properties of RhB and its intermediates were evaluated by quantitative structure-activity relationship prediction. This work will not only provide a reference for developing photocatalytic persulfate activators but also gain an insight into the degradation pathways of RhB and the toxicity of its intermediates.

Progress of disinfection catalysts in advanced oxidation processes, mechanisms and synergistic antibiotic degradation

Human diseases caused by pathogenic microorganisms make people pay more attention to disinfection. Meanwhile, antibiotics can cause microbial resistance and increase the difficulty of disease treatment, resulting in risk of triggering a vicious circle. Advanced oxidation process (AOPs) has been widely studied in the field of synergistic treatment of the two contaminates. This paper reviews the application of catalytic materials and their modification strategies in the context of AOPs for disinfection and antibiotic degradation. It also delves into the mechanisms of disinfection such as the pathways for microbial inactivation and the related influencing factors, which are essential for understanding the pivotal role of catalytic materials in disinfection principles by AOPs. More importantly, the exploratory research on the combined use of AOPs for disinfection and antibiotic degradation is discussed, and the potential and prospects in this field is highlighted. Finally, the limitations and challenges associated with the application of AOPs in disinfection and antibiotic degradation are summarized. It aims to provide a starting point for future research efforts to facilitate the widespread use of advanced oxidation processes in the field of public health.

Nanoporous hydrogel absorbent based on salep: Swelling behavior and methyl orange adsorption capacity

This study used the gas-blowing method to develop a nanoporous hydrogel using poly (3-sulfopropyl acrylate-co-acrylic acid-co-acrylamide) grafted onto salep. The synthesis of the nanoporous hydrogel was optimized by various parameters for maximum swelling capacity. The nanoporous hydrogel was characterized using FT-IR, TGA, XRD, TEM, and SEM analyses. Images from SEM showed numerous pores and channels in the hydrogel with an average size of about 80 nm, forming a honeycomb-like shape. The change in surface charge was investigated by zeta potential and revealed that the surface charge of the hydrogel ranged from 20 mV at acidic conditions to -25 mV at basic conditions. The swelling behavior of optimum superabsorbent hydrogel was determined under different environmental conditions, such as different pH values, ionic strengths of the environment, and solvents. In addition, the swelling kinetics and the absorbance under loading of the hydrogel sample in different environments were investigated. Moreover, Methyl Orange (MO) dye was removed from aqueous solutions using the nanoporous hydrogel as an adsorbent. The adsorption behavior of the hydrogel was examined under various conditions, and the adsorption capacity of the hydrogel was found tobe 400 mg g^-1. The maximum water uptake was obtained under the following conditions: Salep weight = 0.01 g, AA = 60 μL, MBA = 300 μL, APS = 60 μL, TEMED = 90 μL, AAm = 600 μL, and SPAK = 90 μL. Lastly, the adsorption kinetics was studied by employing pseudo-first-order, pseudo-second-order, and intra-particle diffusion models.

3D porous carbon-embedded nZVI@Fe2O3 nanoarchitectures enable prominent performance and recyclability in antibiotic removal

Overcoming the instability and poor recyclability during the practical applications of contaminant scavengers is a challenging topic. Herein, a three-dimensional (3D) interconnected carbon aerogel (nZVI@Fe₂O₃/PC) embedding a core-shell nanostructure of nZVI@Fe₂O₃ was elaborately designed and fabricated via an in-situ self-assembly process. The porous carbon with 3D network architecture exhibits strong adsorption towards various antibiotic contaminants in water, where the stably embedded nZVI@Fe₂O₃ nanoparticles not only serve as magnetic seeds for recycling, but also avoid the shedding and oxidation of nZVI in the adsorption process. As a result, nZVI@Fe₂O₃/PC efficiently captures sulfamethoxazole (SMX), sulfamethazine (SMZ), ciprofloxacin (CIP), tetracycline (TC) and other antibiotics in water. In particular, an excellent adsorptive removal capacity of 329 mg g^-1 and a rapid capture kinetics (99% of removal efficiency in 10 min) under a wide pH adaptability (2-8) are achieved using nZVI@Fe₂O₃/PC as an SMX scavenger. nZVI@Fe₂O₃/PC displays exceptional long-term stability given that it shows excellent magnetic property after it is stored in water solution for 60 d, making it an ideal stable scavenger for contaminants in an etching-resistant and efficient manner. This work would also provide a general strategy to develop other stable iron-based functional architectures for efficient catalytic degradation, energy conversion and biomedicine.

Preparation of sludge-cyanobacteria composite carbon for synergistically enhanced co-removal of Cu(II) and Cr(VI)

Traditional sludge disposal is currently restricted by the risk of secondary pollution. Sludge carbon material has gained widespread attention because of its low cost and environmentally sustainable properties. However, owing to the high ash content and low-energy density of sludge, sludge pyrolysis alone has certain limitations, and the performance of carbon materials needs to be improved. Herein, a sludge-cyanobacteria composite carbon (SCC) was easily synthesized, and the adsorption process of Cu(II) and Cr(VI) by SCC was examined. SCC-700-2-50% exhibited a high S_BET (1047.54 m²/g) and developed pore structure rich in functional groups (such as -NH, -OH, and C-O). The combination of pore structure and functional groups improved the adsorption performance of SCC. The adsorption processes exhibited a synergistic effect in a binary system: the q_m of Cu(II) and Cr(VI) were 386 mg/g and 341 mg/g, respectively, and the selectivity of Cu(II) adsorption by SCC was greater than Cr(VI). The adsorption process, examined by SEM-EDS, FTIR, and XPS analysis, indicated that Cu(II) as a cationic interface strengthens Cr(VI) adsorption through electrostatic interaction, and the anion Cr(VI) created a valid electrostatic shield against the electrostatic repulsion between H⁺ and Cu(II), facilitating Cu(II) adsorption. SCC had great reusability: Cu(II) and Cr(VI) adsorption capacity were 90% and 84%, of the initial adsorption capacity, respectively, after six cycles. This study demonstrates the prospect of SCC as a valid adsorbent for multiple heavy metal contaminations removal.

Organophosphate Esters (OPEs) Flame Retardants in Water: A Review of Photocatalysis, Adsorption, and Biological Degradation

As a substitute for banned brominated flame retardants (BFRs), the use of organophosphate esters (OPEs) increased year by year with the increase in industrial production and living demand. It was inevitable that OPEs would be discharged into wastewater in excess, which posed a great threat to the health of human beings and aquatic organisms. In the past few decades, people used various methods to remove refractory OPEs. This paper reviewed the photocatalysis method, the adsorption method with wide applicability, and the biological method mainly relying on enzymolysis and hydrolysis to degrade OPEs in water. All three of these methods had the advantages of high removal efficiency and environmental protection for various organic pollutants. The degradation efficiency of OPEs, degradation mechanisms, and conversion products of OPEs by three methods were discussed and summarized. Finally, the development prospects and challenges of OPEs’ degradation technology were discussed.

Metal-organic frameworks in photocatalytic Z-scheme heterojunctions: an emerging technology

There is an urgent need for cleaner production processes for chemicals. An efficient and promising alternative for such reactions is heterogeneous photocatalysis, which works on the principle of converting (visible) light, including solar energy, into chemical energy. To that end, properly designed semiconductor based photocatalysts are necessary to trigger the photocatalytic reactions. Many commonly used photocatalysts have too large bandgaps (3-3.4 eV) to use visible light and a too low surface area for efficient production. Metal-organic frameworks (MOFs) have emerged as an encouraging class of materials for photocatalytic applications due to their (i) large surface area and porosity that facilitate adsorption towards chemicals, (ii) tunable crystallinity and optical and electronic properties for efficient light absorption in the visible region, (iii) tunable composition and functionality that make them versatile photocatalysts for a wide range of reactions, and (iv) facile development of composites with other semiconductors to produce Z-scheme heterojunctions that can effectively suppress the recombination of photogenerated charges. Ongoing research has started focusing on the judicious construction of Z-scheme heterojunctions in MOFs, to mimic natural photosynthesis, such that the MOF photocatalysts have higher light harvesting capacity, spatially separated reductive and oxidative active sites, and well-preserved redox ability. This review provides a concise compilation of the recent progress in the development and applications of MOF-based Z-scheme photocatalysts, their advanced characterization, and future perspectives for further advancements.

Non-toxic and biodegradable κ-carrageenan/ZnO hydrogel for adsorptive removal of norfloxacin: Optimization using response surface methodology

Antibiotic resistance is increasing globally due to increased prescription and easy dispensing of antibiotic drugs universally. Hence, to mitigate this effect, efficient, biodegradable, and non-toxic adsorbents are required to be developed. Carrageenan (CG), a natural polymer, having multiple functional groups, provides a backbone for crosslinking with borax and incorporation of ZnO nanoparticles that formed borax-cross-linked κ-carrageenan (CG/Bx/ZnO) hydrogel which is used for efficient adsorption of norfloxacin from water. Surface morphology of as-synthesized hydrogel revealed the rough surface, which was determined by FESEM. Surface area of CG/Bx/ZnO hydrogel was found to be 22.90 m²/g with 3.41 nm pore radius. Systematic batch adsorption studies revealed that 99.4 % removal efficiency could be achieved at a dosage level of 20 mg/L of norfloxacin with 10 mg of hydrogel at pH of 4 in 8 h at room temperature. Experimentally optimized key parameters affecting the overall efficiency of adsorption matched well with the results assessed from ANOVA using Box-Behnken composite design model. The adsorption process was well fitted with the pseudo-second-order model and Langmuir isotherm with 1282.05 mg/g adsorption capacity. Thermodynamic study results show that adsorption is spontaneous and endothermic. The CG/Bx/ZnO hydrogel demonstrated excellent repeatability with minimal loss in norfloxacin adsorption for seven cycles.

Visible light enhanced persulfate activation for degradation of tetracycline via boosting adsorption of persulfate by ligand-deficient MIL-101(Fe) icosahedron

In this work, Fe-based metal-organic frameworks (Fe-MOFs) are prepared by a simple solvothermal method, in which acetic acid/N, N-dimethylformamide (HAc/DMF) mixture solvents are employed to regulate the particle morphology, exposed facets and ligand defects. At HAc/DMF = 0/50, 5/45 and 8/42 (volume ratio), the irregular particles (MIL-53(Fe)), elongated icosahedrons (5H-MIL-101(Fe)) and icosahedrons (8H-MIL-101(Fe)) are obtained, respectively. Under visible light irradiation (λ > 420 nm) and the addition of sodium persulfate (PS), 5H-MIL-101(Fe) shows the highest degradation activity for tetracycline (TC). Specifically, 80% of TC has been removed by 5H-MIL-101(Fe) within 25 min, and the degradation kinetics rate is 3.03 times higher than that over MIL-53(Fe). The improvement of catalytic activity is mainly attributed to the active facets exposed and ligand defects of 5H-MIL-101(Fe). Density functional theory (DFT) calculation further confirms that the active facets exposed and ligand defects of 5H-MIL-101(Fe) favor the adsorption and activation of PS, benefiting the generation of •SO₄^-. Besides, a probable degradation pathway of TC is proposed based on trapping experiments and liquid chromatography-mass spectrometry (LC-MS) test. Furthermore, the toxicities of intermediates are predicted by the quantitative structure-activity relationship (QSAR) mathematical model. This work demonstrates that visible light enhanced PS activation (Vis-PSA) can more effectively degrade organic pollutants, and this work also provides a simple strategy to precisely regulate ligand defects and actively exposed facets of Fe-MOFs to enhance the adsorption and activation of PS.

Synthesis of cerium oxide embedded perovskite type bismuth ferrite nanocomposites for sonophotocatalysis of aqueous micropollutant ibuprofen

Ibuprofen is potentially toxic and carcinogenic for freshwater ecosystems and poses a serious threat to human health by affecting kidney function. The present study focused on the sunlight-controlled degradation of ibuprofen from water using a novel magnetically separable cerium oxide-embedded bismuth ferrite heterostructure. Catalysts were synthesized by solvothermal and co-precipitation methods and characterized by X-ray diffractometry, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis optical absorption spectroscopy, and nitrogen adsorption. This study investigated the effect of photocatalysis, sonolysis, sonophotolysis, and sonophotocatalysis on the degradation of ibuprofen in water. Pseudo-first-order and second-order kinetics were applied to evaluate the rate of reaction for ibuprofen degradation. The addition of 5% CeO₂ to the BiFeO₃ significantly increased the surface area and pore volume of bismuth ferrite, which enhanced their photocatalytic degradation efficiency by 2.28 times in terms of ibuprofen mineralization. Sonolysis treatment alone and in combination with photolysis led to the degradation of ibuprofen, but with the formation of intermediate products. Positive synergy was observed when sonolysis was combined with photocatalysis in terms of the mineralization of ibuprofen and the degradation of intermediates along with their parent compound. It was proposed that, compared to photocatalytic mineralization, the ultrasound-assisted advanced oxidation process resulted in the conversion of ibuprofen to its mineralization products.

Efficient Biosorption of Hexavalent Chromium from Water with Human Hair

The triphenyl group (trityl radical) possessing three-phenyl rings, self-assembled through aromatic π-π stacking interactions, can form interesting crystalline organic nano-flowers. In this work, we have synthesized a hybrid material of 1,2-bis(tritylthio)ethane and magnetite, which reduces toxic Cr(VI) to non-toxic Cr(III). We validated the efficacy of the hybrid in reducing toxic Cr(VI) along with three other adsorbent systems. Among the five adsorbent systems tested, we observed that human hair has higher Cr removal efficiency, which prompted us to explore further using different mechanical forms of human hair. Pulverized hair (PH), hair powder (HP), and raw hair (RH) were evaluated by employing different reaction factors such as the adsorbent dose, pH, initial Cr(VI) concentration, and contact time. The comparative evaluation showed that PH has greater adsorption capacity (15.14 mg/g), followed by RH (13.27 mg/g) and HP (10.5 mg/g). While investigating the adsorption mechanism, we observed that it follows pseudo-second-order kinetics suggesting chemisorption. The Freundlich isotherm model fitted well for Cr(VI) adsorption by human hair, suggesting a multi-layered adsorption process. Overall, this study promises a cost-effective and eco-friendly bio-adsorbent for Cr(VI), which may be scaled up to design automated industrial waste disposal systems.

Oxygen-Deficient Engineering for Perovskite Oxides in the Application of AOPs: Regulation, Detection, and Reduction Mechanism

A perovskite catalyst combined with various advanced oxidation processes (AOPs) to treat organic wastewater attracted extensive attention. The physical and chemical catalytic properties of perovskite were largely related to oxygen vacancies (OVs). In this paper, the recent advances in the regulation of OVs in perovskite for enhancing the functionality of the catalyst was reviewed, such as substitution, doping, heat treatment, wet-chemical redox reaction, exsolution, and etching. The techniques of detecting the OVs were also reviewed. An insight was provided into the OVs of perovskite and reduction mechanism in AOPs in this review, which is helpful for the reader to better understand the methods of regulating and detecting OVs in various AOPs.

Ti/PbO2 Electrode Efficiency in Catalytic Chloramphenicol Degradation and Its Effect on Antibiotic Resistance Genes

Livestock farming has led to the rapid accumulation of antibiotic resistance genes in the environment. Chloramphenicol (CAP) was chosen as a model compound to investigate its degradation during electrochemical treatment. Ti/PbO₂ electrodes were prepared using electrodeposition. The prepared Ti/PbO₂-La electrodes had a denser surface and a more complete PbO₂ crystal structure. Ti/PbO₂-Co electrodes exhibited improved electrochemical catalytic activity and lifetime in practice. The impact of different conditions on the effectiveness of CAP electrochemical degradation was investigated, and the most favorable conditions were identified (current density: I = 15.0 mA/cm, electrolyte concentration: c = 0.125 mol/L, solution pH = 5). Most importantly, we investigated the effects of the different stages of treatment with CAP solutions on the abundance of resistance genes in natural river substrates (intI1, cmlA, cmle3, and cata2). When CAP was completely degraded (100% TOC removal), no effect on resistance gene abundance was observed in the river substrate; incomplete CAP degradation significantly increased the absolute abundance of resistance genes. This suggests that when treating solutions with antibiotics, they must be completely degraded (100% TOC removal) before discharge into the environment to reduce secondary pollution. This study provides insights into the deep treatment of wastewater containing antibiotics and assesses the environmental impact of the resulting treated wastewater.

Influencing Factors and Kinetics of Modified Shell Powder/La-Fe-TiO2 Photocatalytic Degradation of Pyridine Wastewater

Modified Shell Powder/La-Fe-TiO₂ (La-Fe-TiO₂@MSP) composites were fabricated using the sol-gel method and characterized by SEM, XRD, UV-vis DRS and photocurrent techniques, and their physicochemical and optical properties were analyzed. The effects of various factors on the photocatalytic degradation of pyridine and its reaction kinetics were investigated by batch experiments using pyridine, a typical nitrogen-containing heterocyclic compound in coal chemical wastewater, as the target removal species. The pyridine degradation rate of 80.23% was obtained for 800 mg/L composite solution by photocatalytic oxidation of 50 mg/L pyridine wastewater for 180 min at 35 °C, pH = 8 and light intensity of 560 W. The photocatalytic degradation performance was optimal. The quenching experiments determined that the active species of photodegradation were mainly hole and hydroxyl radicals, and the photocatalytic degradation mechanism was analyzed in this way.

Photothermal Localization in an Optofluidic Microreactor for Rapid Pretreatment toward Online Pollutant Analysis

The realization of high-efficient digestion in a microfluidic reactor is considered to be advantageous for pretreatment toward online pollutant detection. However, it is difficult to achieve satisfactory device performance due to the gap between the low digestion reaction efficiency and the demand for rapid pretreatment for online detection. Herein, we design and manufacture an optofluidic microreactor combined with a MnO₂ nanofilm localizing the heat inside the reaction chamber under solar irradiation, which contributes a lot to the on-chip nutrient digestion efficiency enhancement. The overall temperature of the water sample in the reactor chamber can be dramatically increased in a fleeting time of less than 1 s and maintained at 78 °C. The digestion rate constant of the microreactor is improved by about 100 times compared with that obtained by the traditional method in the national standard, which is attributed to temperature enhancement and various oxidation reactions in the heated reaction chamber. Notably, when pretreating the actual total phosphorus water samples, the digestion efficiency is demonstrated to be higher than 95% within 12 s under solar light irradiation. The optofluidic platform brings many benefits to accelerate the various photochemically enhanced reactions using solar light and is extremely adapted for rapid pretreatment of biochemical samples to further develop their online analysis.