Degradation Of Pollutants Research Articles

Ceria nanoparticles: biomedical applications and toxicity.

Ceria nanoparticles (CeO2 NPs) have become popular materials in biomedical and industrial fields due to their potential applications in anti-oxidation, cancer therapy, photocatalytic degradation of pollutants, sensors, etc. Many methods, including gas phase, solid phase, liquid phase, and the newly proposed green synthesis method, have been reported for the synthesis of CeO2 NPs. Due to the wide application of CeO2 NPs, concerns about their adverse impacts on human health have been raised. This review covers recent studies on the biomedical applications of CeO2 NPs, including their use in the treatment of various diseases (e.‍g., Alzheimer's disease, ischemic stroke, retinal damage, chronic inflammation, and cancer). CeO2 NP toxicity is discussed in terms of the different systems of the human body (e.‍g., cytotoxicity, genotoxicity, respiratory toxicity, neurotoxicity, and hepatotoxicity). This comprehensive review covers both fundamental discoveries and exploratory progress in CeO2 NP research that may lead to practical developments in the future.

Tackling Losartan Contamination: The Promise of Peroxymonosulfate/Fe(II) Advanced Oxidation Processes

Losartan, an angiotensin II receptor antagonist frequently detected in wastewater effluents, poses considerable risks to both aquatic ecosystems and human health. Seeking to address this challenge, advanced oxidation processes (AOPs) emerge as robust methodologies for the efficient elimination of such contaminants. In this study, the degradation of Losartan was investigated in the presence of activated peroxymonosulfate (PMS), leveraging ferrous iron as a catalyst to enhance the oxidation process. Utilizing advanced analytical techniques such as NMR and mass spectrometry, nine distinct byproducts were characterized. Notably, seven of these byproducts were identified for the first time, providing novel insights into the degradation pathway of Losartan. The study delved into the kinetics of the degradation process, assessing the degradation efficiency attained when employing the catalyst alone versus when using it in combination with PMS. The results revealed that Losartan degradation reached a significant level of 64%, underscoring the efficacy of PMS/Fe(II) AOP techniques as promising strategies for the removal of Losartan from water systems. This research not only enriches our understanding of pollutant degradation mechanisms, but also paves the way for the development of sustainable water treatment technologies, specifically targeting the removal of pharmaceutical contaminants from aquatic environments.

Solar-driven Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 heterojunction for efficient degradation of organic pollutants: Insights into adsorption mechanism, charge transfer and degradation pathway

Actualizing controllable construction of efficient heterojunction nanocomposites remains a challenge in the field of photocatalytic water remediation, which can be got over through exploiting in-situ attachment approaches between different semiconductors. Based on this, we successfully fabricated a unique separable Z-scheme Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 (BON/BW) nanoflowers by an in-situ growth strategy. The profitable photogenerated carriers transfer mediated by Z-scheme heterojunction greatly accelerated the generation of •O2– and •OH. The strong adsorption of 4-nitrophenols (4-NP) with parallel configuration on side Bi2WO6 in BON/BW nanocomposites also provides great convenience for subsequent degradation steps. By optimizing multiple steps in the photocatalytic reaction process, BON/BW showed far superior photodegradation performance compared to single components. The causes and consequences of 4-NP photodegradation were explored through LC-MS tests, theoretical calculations, and toxicity analysis, and a green and safe degradation pathway was proposed. More experiments have confirmed that the synthesized BON/BW composites also have excellent degradation ability against other pollutants under sunlight, demonstrating excellent universality. With any luck, the logical design of heterojunction photocatalysts for effective photocatalytic water remediation should be aided by this study.

MOF-on-MOF-derived Fe[sbnd]Zr bimetal oxides supported on hierarchically porous carbonized wood to promote photo-Fenton degradation of ciprofloxacin

MOF-on-MOF derivatives have served as promising heterogeneous Photo-Fenton (hetero-PF) catalysts, but its self-aggregation instability and limited photocatalytic activity inhibit the effective ciprofloxacin (CIP) removal. In this study, a novel hetero-PF catalyst, dual MOF-derived FeZr bimetal oxide embedded in a wood-converted porous carbon skeleton (ZrO2@Fe3O4/WPC), was successfully synthesized via a straightforward in-situ growth strategy combined with co-pyrolysis. The as-prepared hybrid photocatalysts, featuring a large surface area, effective porous structures, efficient light absorption and a narrow band gap demonstrated superior photo-Fenton activity, accomplishing approximately 99.1 % degradation of CIP within 120 min under neutral conditions. Furthermore, the ZrO2@Fe3O4/WPC hetero-PF system showed satisfactory performance in treating real water matrices. It can be inferred that the abundant heterojunctions, resulting from the synergistic effect of FeZr mixed oxide and the porous carbonized wood substrate, contributed to the rapid separation and migration of photogenerated electron-hole pairs. Meanwhile, the FeZr site in the graphitized carbon framework activates H2O2 to accelerate the generation of the OH and O2− radicals, leading to a heightened degradation efficiency of CIP. Besides, the photodegradation pathway of CIP is obtained by liquid chromatography-mass spectrometry (LC-MS). This study indicates that combining porous carbonized wood and heterometallic MOF derived materials provides a promising method for realizing high-efficiency photo-Fenton degradation of antibiotic water pollutions.

Efficient catalytic degradation of carbamazepine using single-atom Ru-NiFe-LDH: Role of 1O2 and selective degradation

The targeted elimination of stubborn organic pollutants is crucial for human health and ecosystem well-being. Thanks to its exceptional efficiency and other benefits, peroxymonosulfate offers extensive potential for water treatment. However, realizing the practical application of this technology hinges on creating a high-efficiency catalyst. This study presents the fabrication of a monoatomic Ru catalyst through a straightforward hydrothermal approach. Synchrotron radiation and spherical electron microscopy were used to confirm the binding of monoatomic Ru to the NiFe-LDH (Layered Double Hydroxide, LDH) surface. Using a catalyst containing 0.77 wt% of single-atom Ru, 20 mg/L of Carbamazepine (CBZ) could be eliminated within 25 mins. With this, an impressive pseudo-first-order reaction rate constant of 0.118 min−1 was attained. The feasibility of the catalyst was evaluated in a column experimental reactor. The removal rate of 0.5 g of catalyst in wastewater containing 20 mg/L CBZ reached 100 %, demonstrating sustained operation for 720 mins. Ru-LDH/PMS system preferentially degrades carbamazepine, ciprofloxacin and other pollutants. This may be related to the structure and HOMO value of the pollutants and the active factors stimulated by Ru-LDH. Through a range of probe reactions and spectral analysis, it was determined that 1O2 played a pivotal role in pollutant degradation, closely linked to the presence of Ru.

Ag‐Based Bimetallic Nanoparticles for the Catalytic Reduction of Nitrophenol and Organic Dyes: An Overview

AbstractBimetallic nanoparticles with synergistic effects revealed much higher catalytic activity than respective monometallic materials. This review describes bimetallic nanoparticles, especially silver nanoparticles, combined with the other transition elements, such as Ag−Fe, Ag−Co, Ag−Ni, and Ag−Cu, as an enhanced catalytically active material. The coverage is given to the various methods of preparation, in which factors responsible for different structures of bimetallic nanoparticles are thoroughly discussed. Lastly, we explore the use of bimetallic nanoparticles as a catalyst for the degradation of numerous organic pollutants that contribute to water pollution.

Efficient electro-Fenton degradation of organic pollutants via the synergistic effect of 1O2 and •OH generated on single Fe[sbnd]N4 sites

The electro-Fenton with in situ generated 1O2 and •OH is a promising method for the degradation of micropollutants. However, its application is hindered by the lack of catalysts that can efficiently generate 1O2 and •OH from electrochemical oxygen reduction. Herein, N-doped stacked carbon nanosheets supported Fe single atoms (Fe-NSC) with FeN4 sites were designed for simultaneous generation of 1O2 and •OH to enhance electro-Fenton degradation. Due to the synergistic effect of 1O2 and •OH, a variety of contaminants (phenol, 2,4-dichlorophenol, sulfamethoxazole, atrazine and bisphenol A) were efficiently degraded with high kinetic constants of 0.037–0.071 min−1 by the electro-Fenton with Fe-NSC as cathode (−0.6 V vs Ag/AgCl, pH 6). Moreover, the superior performance for electro-Fenton degradation was well maintained in a wide pH range from 3 to 10 even with interference of various inorganic salt ions. It was found that FeN4 sites with pyridinic N coordination were responsible for its good performance for electro-Fenton degradation. Its 1O2 yield was higher than •OH yield, and the contribution of 1O2 was more significant than •OH for pollutant degradation.

Ultrafast catalytic reduction of organic pollutants using ternary zinc–copper–nickel layered double hydroxide

Water is the utmost essential commodity for the support of life process in animals. In recent decades, rapid industrialization and uncontrolled agricultural practices have led to increased level of toxic pollutants in groundwater, including organic pollutants (dyes, nitroarene compounds, antibiotics, etc.), inorganic pollutants (heavy metals, nanoparticles, etc.), and pesticides, posing a serious threat to human health and the environment. Although various technologies such as adsorption, photocatalysis, reverse osmosis, filtration, sedimentation, flocculation, and precipitation are available for the elimination of toxic pollutants from wastewater, issues such as their cost and efficacy limit their usage. Recently, catalysis has been found to be the most effective approach since it exhibits significant capability to eliminate almost all the pollutants and offers the benefit of simple design and low initial cost. In the present study, ternary zinc–copper–nickel layered double hydroxide (ZnCuNi‐LDH) synthesized using facile acid hydrolysis method was employed as an efficacious heterogeneous catalyst for the reduction of NACs (para‐nitrophenol and para‐nitroaniline) and degradation of organic azo dyes (methyl orange, amaranth, and brilliant black). ZnCuNi‐LDH exhibited superior catalytic activity for the reduction of all five model pollutants with reduction efficiency of more than 95% within a short time span of 5 min. Therefore, keeping in view the layered structure, high specific surface area, and remarkable catalytic performance, ZnCuNi‐LDH holds immense potential for the large‐scale catalytic degradation of refractory pollutants.

A sustainable electrochemical strategy utilizing pulsed alternating current and dual carbon felt electrodes for enhanced degradation of organic pollutants: Oxidation performance and mechanisms

In this work, a novel electrochemical (EC) oxidation system utilizing pulsed alternating current (PAC) and dual carbon felt (CF) electrodes has been established for sustainable degradation of sulfamethoxazole (SMX) with no addition of extra oxidant. The EC/PAC system showed high degradation efficiency and energy efficiency compared to the pulsed direct current (PDC) and direct current (DC) systems. The EC/PAC process was effective across a wide pH range of 3–11 for SMX removal. The results showed that the 1O2 confined to the CF electrode surface was the dominant oxidative specie that was generated from dissolved oxygen in the system. Under PAC conditions, the cathode and anode were rapidly switched on the same CF electrode, increasing the generation of 1O2 for enhanced SMX oxidation. Furthermore, the EC/PAC system demonstrated resistance to interference from various anions of different concentration levels found in natural environment. In contrast to the EC/PDC system, the EC/PAC system emerged as a promising option for more efficient H2O2 production. High-resolution mass spectrometry results revealed the SMX degradation pathways and byproducts, which were then evaluated for toxicity removal. Overall, the EC/PAC system offers a green and sustainable solution to future wastewater treatment, with high degradation rates, energy efficiency, and sustainability.

Tailoring the surface functional groups of biochar for enhanced adsorption and degradation of pharmaceutically active compounds

In this study, orange peel biochar (OPBC) was synthesized through a pyrolysis process. Decoration with two specific functional groups (i.e., –COOH and NH2) was performed through a ball milling-assisted modification process to yield the respective biochars (i.e., OPBC-COOH and OPBC-NH2). Both OPBC-COOH and OPBC-NH2 demonstrated excellent adsorption capacities for sulfamethoxazole (SMX) and carbamazepine (CBZ), and hydrogen bonding between the pharmaceuticals and BCs followed the primary adsorption mechanism. In addition, both OPBC-COOH and OPBC-NH2 (0.3 g/L) exhibited high degradation efficiencies for SMX (10 mg/L, 87 %; 92 %) and CBZ (10 mg/L, 73 %; 83 %) when peroxymonosulfate (PMS, 1 mM) was present. The scavenging experiments confirmed that electron transfer and radical/non-radical pathways (·OH and 1O2) are mainly responsible for the degradation of SMX and CBZ, respectively. It was also proven that the oxygen- and nitrogen-containing surface functional groups on BC are important for activating PMS for the degradation of organic pollutants. These findings provide new insights into the effects of functional groups on BC for the degradation of contaminants of emerging concern.

Encapsulating stable perovskite catalysts in hollow nanoreactors for enhanced pollutants degradation

Creating a microenvironment for enhanced peroxymonosulfate (PMS) activation is vital in advanced oxidation processes. The objective of this study was to fabricate nanoshells composed of titanium dioxide embedded with cobalt titanate nanoparticles of perovskite to act as nanoreactors for effectively initiating PMS and degrading contaminants. The unique porous structure and confined space of the nanoreactor facilitated reactant absorption and mass transfer to the active sites, resulting in exceptional catalytic performance for pollutant elimination. Experimental findings revealed close to 100% decomposition efficiency of 4-chlorophenol (4-CP) within an hour utilizing the nanoreactors over a wide pH range. The TiO2/CoTiO3 hollow nanoshells catalysts also displayed adaptability in disintegrating organic dyes and antibiotics. The radicals SO4•-, •OH, and non-radicals 1O2 were determined to be accountable for eliminating pollutants, as supported by trapping experiments and electron paramagnetic resonance spectra. The catalyst was confirmed as an electron donor and PMS as an electron acceptor through electrochemical tests and density functional theory calculations. This study underscores the potential of incorporating stable perovskite catalysts in hollow nanoreactors to enhance wastewater treatment.

Amorphous nitrogen-doped carbon layers forming the interfacial channel for rapid charge transfer in ZnIn2S4/BiVO4 Z-scheme photocatalyst for enhancing organic pollutants degradation with simultaneous hydrogen evolution

Efficient photocatalytic hydrogen evolution from the organic wastewater represents an ideal solution for simultaneously addressing energy shortages and environmental pollution. However, the sluggish transport of photogenerated carriers at contact interface poses a key obstacle to enhancing photocatalytic activity. Here, ZnIn2S4/BiVO4@N-C (ZIS/BVO@N-C) Z-scheme photocatalysts were successfully constructed by a simple hydrothermal-impregnation method. ZIS/BVO@N-C-10% demonstrated outstanding photocatalytic performance, achieving a hydrogen evolution rate of 2695.68 μmol·g−1·h−1 and a degradation rate of 492.96 mmol·g−1·h−1 under visible light, surpassing those of ZIS (851.52 μmol·g−1·h−1 and 174.83 mmol·g−1·h−1) and ZIS/BVO-10% (1228.98 μmol·g−1·h−1 and 277.78 mmol·g−1·h−1). Characterization results and density functional theory (DFT) calculations revealed that the introduction of the N-C layer reduced interfacial impedance and enhanced the strength of interfacial electric field, overcoming the interfacial barrier and improving the photogenerated separation and migration efficiency at the interface, and ultimately enhancing the photocatalytic activity of ZIS/BVO@N-C. Based on experimental and characterization results, the photocatalytic mechanism of ZIS/BVO@N-C Z-scheme has been proposed. Furthermore, ZIS/BVO@N-C exhibited excellent stability, highlighting its potential for practical applications. This work also presents a new strategy for designing highly active Z-scheme photocatalysts for organic wastewater treatment and simultaneous hydrogen energy recovery.

A flexible self-cleaning/antibacterial PVDF/T-ZnO fabric based on piezo-photocatalytic coupling effect for smart mask

A novel flexible composite fabric has been engineered by combining piezoelectric poly (vinylidene fluoride) (PVDF) and tetrapod zinc oxide (T-ZnO) nanostructures, which are integrated onto a nonwoven fabric substrate. This fabric exhibits a wide array of functionalities, notably self-cleaning and antibacterial properties, facilitated by the synergistic piezo-photocatalytic coupling effect. Through the utilization of the piezoelectric effect inherent in PVDF/T-ZnO in tandem with the photocatalytic attributes of T-ZnO nanostructures, the fabric achieves concurrent degradation of organic pollutants and antibacterial efficacy when exposed to mechanical vibration and solar irradiation. The piezo-photocatalytic coupling effect engenders an internal electric field that aids in the effective separation of photo-generated carriers (electrons and holes), thereby diminishing recombination rates and augmenting the efficiency of the photocatalytic degradation process. Notably, organic pollutants such as methylene blue and azithromycin exhibit degradation levels of 96.0% and 92.6%, respectively, within a timeframe of 25 and 60 min. The incorporation of PVDF/T-ZnO results in an approximate 40% enhancement in the degradation rate of organic substances compared to the use of T-ZnO in isolation. Furthermore, the composite fabric showcases exceptional antibacterial efficacy, effectively inhibiting the proliferation of Staphylococcus aureus. Experimental findings reveal that the average antibacterial zone diameter of the PVDF/T-ZnO fabric measures at 7.68 mm, significantly surpassing that of the T-ZnO fabric and nonwoven fabric. Given its remarkable self-cleaning and antibacterial attributes, the PVDF/T-ZnO fabric exhibits substantial potential for diverse applications, including the development of intelligent masks tailored for deployment in healthcare settings and polluted environments.

Fabrication of porous biochar supported Bi2MoO6 photocatalyst for efficient degradation of ciprofloxacin in seawater under visible light irradiation: Mechanistic investigation and intermediates analysis

Efficient separation of photocarriers is a critical approach for advancing high-performance photocatalyst systems to effectively remove environmental contaminants. In this investigation, a hydrothermal technique was employed to synthesize composites of Bi2MoO6 and porous biochar derived from banana peels (BPB). The samples underwent various characterization methods to assess their composition, morphology, and photoelectrochemical properties. The BPB/Bi2MoO6 composite exhibited a synergistic adsorption and photocatalytic impact in eliminating the antibiotic ciprofloxacin (CIP) from pure water and seawater. The optimized BPB/Bi2MoO6 sample displayed a significant degradation efficiency of 98.7 % for CIP after 90 min of visible-light exposure in pure water. In artificial seawater, the degradation efficiency for CIP remained high at 93.6 %, which was 12.2 times greater than that of pure Bi2MoO6. The study also explored the impact of various factors such as catalyst dosage, solution pH, and pollutant concentration on the photocatalytic performance of BPB/Bi2MoO6. Moreover, the catalyst exhibited enhanced efficiency in the adsorption-photocatalytic degradation of CIP within a continuous flow reaction system. The enhanced photocatalytic performance was attributed to the composite's exceptional adsorption capacity, enhanced response to visible light, and efficient separation of photoinduced electron-hole pairs. Furthermore, the BPB/Bi2MoO6 photocatalyst displayed good stability and recyclability over five consecutive photodegradation cycles. Radical trapping and electron spin resonance (ESR) experiments verified that the degradation of CIP was mainly driven by •OH and h+ radicals. A thorough investigation employing density functional theory (DFT), radical trapping and ESR tests, and liquid chromatography mass spectrometry (LC-MS) was conducted to elucidate the degradation mechanism and pathways. Furthermore, toxicity assessment software was utilized to illustrate the progressive reduction in toxicity of the intermediate products. In conclusion, this study provides valuable insights into the role of biochar in enhancing the photocatalytic degradation of pollutants and offers guidance for the future development of environmentally friendly photocatalysts.

Oxygen-Centered Organic Radicals-Involved Unified Heterogeneous Self-Fenton Process for Stable Mineralization of Micropollutants in Water.

Removing organic micropollutants from water through photocatalysis is hindered by catalyst instability and substantial residuals from incomplete mineralization. Here, we present a novel water treatment paradigm, the unified heterogeneous self-Fenton process (UHSFP), which achieved an impressive 32% photon utilization efficiency at 470nm, and a significant 94% mineralization of organic micropollutants-all without the continual addition of oxidants and iron ions. In UHSFP, the active species differs fundamentally from traditional photocatalytic processes. One electron acceptor unit of photocatalyst acquires only one photogenerated electron to convert into oxygen-centered organic radical (OCOR), then spontaneously completing subsequent processes, including pollutant degradation, hydrogen peroxide generation, activation, and mineralization of organic micropollutants. By bolstering electron-transfer capabilities and diminishing catalyst affinity for oxygen in the photocatalytic process, the generation of superoxide radicals is effectively suppressed, preventing detrimental attacks on the catalyst. This study introduces an innovative and cost-effective strategy for the efficient and stable mineralization of organic micropollutants, eliminating the necessity for continuous chemical inputs, providing a new perspective on water treatment technologies. This article is protected by copyright. All rights reserved.

Reverse loading of inert Al2O3 onto active iron oxide for improved H2O2 activation and pollutant degradation

Developing heterogeneous iron-based catalysts with superior reactivity and stability is a long-term goal for hydrogen peroxide (H2O2) activation in Fenton-like technique for water remediation. Supported iron-based nanocomposites are of great interest due to their earth abundance, environmental friendliness, and tunable structure. However, existing iron-based Fenton catalysts are normally designed via the loading of iron-derived nanoparticles onto various inert substrates, where the surface reactive sites are hardly affected by the substrate. Here, we report the first example of reversely loaded FeOx-Al2O3 nanocomposite via overturning the loading direction, i.e., loading inert Al2O3 support onto reactive FeOx nanoparticles. The resultant FeOx@Al2O3-R catalyst demonstrated much improved reactivity for H2O2 activation and bisphenol A removal (by 14 times in terms of first-order rate constant) than its analog FeOx/Al2O3-T, which was prepared via the loading of FeOx nanoparticles onto inert Al2O3 support. Moreover, FeOx@Al2O3-R exhibited excellent stability with Fe leaching only one sixth of FeOx/Al2O3-T. Systematic characterization results revealed that the inert Al ions modify the electronic environment and properties of the surface Fe reactive sites. This work provides an alternative reverse loading strategy to traditional loading method for the preparation of iron-based nanocomposite catalyst that is highly efficient for H2O2 activation and pollutant removal.

Boosting photocatalytic activity in ternary lamellar hierarchical structured ZnFe2O4/polymeric carbon nitride by constructing an electronic bridge

Photocatalytic technology is one of the ideal approaches for clean energy production and environmental pollution control in the future. However, the rapid recombination of photo-generated charge carriers is a bottleneck problem of low solar energy conversion efficiency. Herein, a magnetic ZnFe2O4/Pt/polymeric carbon nitride (PCN) semiconductor catalyst is designed and prepared for high-performance photocatalytic hydrogen production reaction and photocatalytic degradation rate of RhB. It exhibits 339.31 μmol·g−1·h−1 hydrogen production rate and 96.08 % photocatalytic degradation rate of RhB within 120 min under visible light. The introduction of Pt, constructing an electronic bridge, accelerated the transfer of photo-generated carriers, meanwhile, the smaller band gap of the ternary composites enabled the generation of more photo-generated electrons. The internal electric field accelerated the accumulation of electrons and holes in the conduction band of ZnFe2O4 and valence band of PCN, thus photocatalytic activity is greatly enhanced. The electron-hole separation is also improved and the transport of photo-generated electrons is facilitated by the special structure of the heterojunction and the unique morphology of PCN. In addition, the used catalyst can be recovered through magnetic fields, and this magnetic catalytic system has great application prospects in the fields of photocatalytic hydrogen production and pollutant degradation.

Two-step synthesis of coconut shell biochar-based ternary composite to efficiently remove organic pollutants by photocatalytic degradation

Designing environmentally friendly, low cost and efficient photocatalysts is vitally important for degradation of organic pollutants. Herein, a ternary composite-ZnO/ACSC@TiO2, constituted by activated coconut shell derived biochar (ACSC), TiO2 and ZnO, was successfully synthesized by two-step hydrothermal method. It demonstrated that TiO2 could be uniformly wrapped on ACSC surface during first step to form core-shell structures (ACSC@TiO2). It was beneficial not only to enhance adsorption capacity for organic pollutants and absorption ability for light, but also to form C-doped TiO2 with a relatively narrow bandgap to expand light absorption of TiO2 from UV to visible light. Subsequently, ZnO was introduced through second step to generate type-II heterojunctions with ACSC@TiO2, which further reduced bandgap value of the ternary photocatalyst to promote photogenerated carrier generation and efficiently diminished recombination of e--h+ pairs. As expected, the optimal prepared catalyst with 10 wt% of ZnO (10%ZnO/ACSC@TiO2) exhibited excellent adsorptive and photocatalytic abilities for removal of tetracycline (TC) and Rhodamine B (RhB) with different initial concentrations. Particularly, its total removal efficiency for TC and RhB was 97.6% and 99.4%, respectively under 300 W xenon lamp irradiation (25 mg/L of organic pollutants, 1.0 g/L catalyst and natural pH in 60 min). Investigations on catalytic mechanism and degradation pathways proved that 10%ZnO/ACSC@TiO2 could remove RhB and TC by deep degradation. Its enhanced synergy of adsorption and photocatalysis could efficiently accelerate mineralization rates of RhB and TC. This biomass derived biochar-based ternary composite as photocatalyst with optimized energy band structures and microstructures would have good industrial application potential.

Study on the specific photodegradation performance of Fe3O4@SiO2@TiO2@MIPs for berberine hydrochloride

Study on the specific photodegradation performance of Fe3O4@SiO2@TiO2@MIPs for berberine hydrochloride

Semi-rational design of nitroarene dioxygenase for catalytic ability toward 2,4-dichloronitrobenzene.

Rieske non-heme dioxygenase family enzymes play an important role in the aerobic biodegradation of nitroaromatic pollutants, but no active dioxygenases are available in nature for initial reactions in the degradation of many refractory pollutants like 2,4-dichloronitrobenzene (24DCNB). Here, we report the engineering of hotspots in 2,3-dichloronitrobenzene dioxygenase from Diaphorobacter sp. strain JS3051, achieved through molecular dynamic simulation analysis and site-directed mutagenesis, with the aim of enhancing its catalytic activity toward 24DCNB. The computationally predicted activity scores were largely consistent with the detected activities in wet experiments. Among them, the two most beneficial mutations (E204M and M248I) were obtained, and the combined mutant reached up to a 62-fold increase in activity toward 24DCNB, generating a single product, 3,5-dichlorocatechol, which is a naturally occurring compound. In silico analysis confirmed that residue 204 affected the substrate preference for meta-substituted nitroarenes, while residue 248 may influence substrate preference by interaction with residue 295. Overall, this study provides a framework for manipulating nitroarene dioxygenases using computational methods to address various nitroarene contamination problems.IMPORTANCEAs a result of human activities, various nitroaromatic pollutants continue to enter the biosphere with poor degradability, and dioxygenation is an important kickoff step to remove toxic nitro-groups and convert them into degradable products. The biodegradation of many nitroarenes has been reported over the decades; however, many others still lack corresponding enzymes to initiate their degradation. Although rieske non-heme dioxygenase family enzymes play extraordinarily important roles in the aerobic biodegradation of various nitroaromatic pollutants, prediction of their substrate specificity is difficult. This work greatly improved the catalytic activity of dioxygenase against 2,4-dichloronitrobenzene by computer-aided semi-rational design, paving a new way for the evolution strategy of nitroarene dioxygenase. This study highlights the potential for using enzyme structure-function information with computational pre-screening methods to rapidly tailor the catalytic functions of enzymes toward poorly biodegradable contaminants.