Catalyst For Degradation Of Pollutants Research Articles

Rare Earth Doped ZnO Nanoparticles as Spintronics and Photo Catalyst for Degradation of Pollutants.

Antibiotic water contamination is a growing environmental problem in the present day. As a result, water treatment is required for its reduction and elimination. Due to their important role in resolving this issue, photocatalysts have drawn a great deal of interest over the past few decades. When non-biodegradable organic matter is present in polluted water, the photo catalytic process, which is both environmentally friendly and an improved oxidation method, can be an effective means of remediation. In this regard, we report the successful synthesis of pure phased rare earth doped ZnO nanoparticles for tetracycline degradation. The prepared catalysts were systematically characterized for structural, optical, and magnetic properties. The optical band gap was tailored by rare earth doping, with redshift for Sm and Dy doped nanoparticles and blueshift for Nd doped ZnO nanoparticles. The analysis of photoluminescence spectra revealed information about the defect chemistry of all synthesised nanoparticles. Magnetic studies revealed that all synthesized diluted magnetic semiconductors exhibit room temperature ferromagnetism and can be employed for spintronic applications. Moreover, Dy doped ZnO nanoparticles were found to exhibit a maximum degradation efficiency of 74.19% for tetracycline (TCN) removal. The synthesized catalysts were also employed for the degradation of Malachite green (MG), and Crystal violet (CV) dyes. The maximum degradation efficiency achieved was 97.18% for MG and 98% for CV for Dy doped ZnO nanoparticles. The degradation mechanism involved has been discussed in view of the reactive species determined from scavenging experiments.

Enhancement of electrode properties using carbon dots functionalized magnetite nanoparticles for azo dye decolorization in microbial fuel cell

Technology integration of nanomaterials with microbial fuel cell (MFC) have led to simultaneous degradation of recalcitrant dyes and energy extraction from textile wastewater. Limited electron transfer capacity and hydrophobicity of electrode are the bottlenecks for enhancing the performance of MFC. Nanomaterials can provide surface functionalities for electron transfers and serve as catalyst for pollutant degradation. In this paper, magnetite nanoparticles functionalized with carbon dots (Fe3O4@CDs) were used to enhance the electron transfer capacity of the electrodes due to numerous surface-active functional groups of CDs and the reversible redox reaction of Fe2+/Fe3+. Polydopamine (PDA) was used as binder to coat Fe3O4@CDs onto the surface of carbon felt (CF) electrodes in a sono-chemical reaction, favoring to form biocompatible electrodes. Charge transfer resistance of Fe3O4@CDs@PDA-CF was 5.02Ω as compared to 293.34Ω of unmodified CF. Fe3O4@CDs@PDA-CF installed MFC could achieve almost 98% dye degradation efficiency within 48 h and 18.30 mW m−2 power output as compared to 77% dye degradation and 0.34 mW m−2 power output by unmodified CF electrode MFC. Moreover, metagenomic analysis of microbial consortia developed in Fe3O4@CDs@PDA-CF MFC showed enrichment of electrogenic and dye degrading microbial communities of Achromobacter. Delftia, Geobacter and Pseudomonas.

Molten-salts assisted preparation of iron-nitrogen-carbon catalyst for efficient degradation of acetaminophen by periodate activation

Highly efficient and stable heterogeneous catalysts were desired to activate periodate (PI) for sustainable pollution control. Herein, iron-nitrogen-carbon catalyst was synthesized using a facile molten-salts mediated pyrolysis strategy (denoted as FeNC-MS) and employed to activate PI for the degradation of acetaminophen (ACE). Compared with iron-nitrogen-carbon catalyst prepared by direct pyrolysis method (marked as FeNC), FeNC-MS exhibited superior catalytic activity due to its large specific surface area (1600 m2 g−1) and the abundance of FeNx sites. The batch experiments revealed that FeNC/PI process achieved 37 % ACE removal within 20 min, while ACE removal in FeNC-MS/PI process was 98 % under the identical conditions. Integrated with electron paramagnetic resonance tests, quenching experiments, chemical probe identification, and electrochemical experiments, we demonstrated that FeNC-MS-PI complexes-mediated electron transfer was the predominant mechanism for the oxidation of ACE. Further analysis disclosed that FeNx sites in FeNC-MS were the main active sites for the activation of PI. Additionally, FeNC-MS/PI process exhibited significant resistance to humic acid and background electrolyte, and avoided the secondary pollution imposed by Fe leaching. The possible degradation pathways of ACE were proposed. The germination experiments of lettuce seeds showed that the ecotoxicity of ACE solution was significantly reduced after treatment with FeNC-MS/PI process. Overall, this study provided a facile strategy for the synthesis of efficient iron-nitrogen-carbon catalysts and gained fundamental insight into the mechanism of PI activation by iron-nitrogen-carbon catalysts for pollutants degradation.

Tailoring the Surface Properties of Micro/Nanofibers Using 0D, 1D, 2D, and 3D Nanostructures: A Review on Post‐Modification Methods

AbstractMicro‐ and nanofibers produced by electrospinning and solution blow spinning (SBS) are highly suitable platforms for diverse applications due to their advantageous properties, including the high surface area to volume ratio, high porosity, and flexibility. To render them additional functionalities, distinct pre‐ or post‐modification processes have been proposed for modifying such micro‐ and nanofibers with 0D, 1D, 2D, and 3D nanostructures. The pre‐modification requires the addition of 0D–3D nanostructures (or their precursors) into the polymeric phase before the spinning process, which can demand laborious solubilization and requires changes in experimental spinning parameters, with impact on morphology, spinnability, and properties. Post‐modification methods, on the other hand, enable the fabrication of composite fibers without the need to optimize the spinning parameters, allowing a simple and efficient surface modification. Herein, recent advances on post‐modification methods of spun fibers, including wet chemistry, grafting, crosslinking, click chemistry, oxidations, hydrolysis and reduction strategies, dip‐coating, layer‐by‐layer, electro/air‐spray, atomic layer deposition, and plasma techniques aiming at the surface functionalization with 0D–3D nanostructures are surveyed. Recent results, trends, and challenges on the application of such surface‐modified fibers for environmental, industrial, and medical applications, including as adsorbent and filtering membranes, catalysts for pollutants degradation, and wearable sensors are examined.

Biochar: Critical Review on Biochar‐Supported Catalysts for Pollutant Degradation and Sustainable Biorefinery (Adv. Sustainable Syst. 10/2020)

Biochar: Critical Review on Biochar‐Supported Catalysts for Pollutant Degradation and Sustainable Biorefinery (Adv. Sustainable Syst. 10/2020)

Critical Review on Biochar‐Supported Catalysts for Pollutant Degradation and Sustainable Biorefinery

AbstractBiochar (BC) is a material synthesized from biomass by thermochemical conversion. Physicochemical and functional properties of BCs can be enhanced by several methods of activation or functionalization. The activated and functionalized BCs with a large surface area and abundant surface functional groups can serve as effective catalysts or catalyst supports for various chemical transformations as well as for adsorption/sorption/enrichment of low‐concentration pollutant streams. Among them, remediation of environmental contaminants and production of a range of bioproducts in biorefineries have attracted much attention in the context of achieving green and sustainable development. Although the applications of BC as adsorbents in removal of pollutants have been discussed extensively, there is a lot of untapped potential with new applications of BCs as catalysts or catalyst supports for advanced oxidation processes (AOPs) and sustainable biorefineries. In this review, the production and activation/functionalization of BCs are scrutinized. The mechanisms of activated and functionalized BC and BC‐supported catalysts in degradation of organic contaminants via AOPs assisted with hydrogen peroxide (H2O2), peroxydisulfate (PDS), and peroxymonosulfate (PMS) are reviewed. Emerging applications of BC as catalyst for production of biodiesel and high‐value chemicals, tar removal, bio‐syngas reforming, and energy storage and conversion devices are discussed in detail.

Ultrathin Graphitic Carbon Nitride Nanosheets as Efficient Catalysts for Degradation of Pollutants under Visible Light

AbstractIn this paper, ultrathin g‐C3N4 nanosheets (U‐CNs‐4) were prepared via short time sonication‐assisted exfoliation and solvothermal treatment method in ethylene glycol solvent. It was found that the obtained ultrathin g‐C3N4 nanosheets with a thickness of ranges from 4 to 5 nm, exhibited a higher specific surface area of 35.7 m2/g and larger electronic band structure (by 0.16 eV), enhanced photocurrent response and improved electron transport ability due to the quantum confinement effect. The photocatalytic activities have been proved by photocatalytic degradation Rhodamine B (RhB) and ciprofloxacin (CIP) under visible‐light irradiation. Results show that the U‐CNs‐4 exhibited obviously enhanced photocatalytic activity in comparison with other samples. The degradation efficiency of RhB was 4.4 times higher than that of the bulk g‐C3N4 (B‐CN). The enhanced photocatalytic activity was due to the more active sites, the enhanced oxidation ability and improved electron transport ability, which improving separation efficiency of photogenerated electron‐hole pairs. Finally, the possible for the enhancing photocatalytic mechanism was revealed based on the active species trapping and electron spin resonance (ESR) experiments.

Microfluidic Fabrication of Bubble-Propelled Micromotors for Wastewater Treatment.

Bubble-propelled micromotors with controllable shapes and sizes have been developed by a microfluidic method, which serves for effective wastewater treatment. Using the emulsion from microfluidics as the template, monodisperse micromotors can be fabricated in large quantities based on phase separation and UV-induced monomer polymerization. By adjusting the volume ratio of the two immiscible oils (ethoxylated trimethylolpropane triacrylate/paraffin oil) in the initial emulsion, the geometry of the resulting micromotor can be precisely controlled from nearly spherical, hemispherical to crescent-shaped. The size of the micromotor can be manipulated by varying the fluid flow parameters. In addition, by incorporating functional nanoparticles into the asymmetric structure, the micromotor can be functionalized flexibly for water remediation. In this research, Fe3O4 and MnO2 nanoparticles were successfully loaded on Janus micromotors. Fe3O4 nanoparticles can act as catalysts for pollutant degradation and also control the movement direction of micromotors. MnO2 nanoparticles on the concave of the micromotor catalyzed H2O2 to produce bubble propulsion motion in solution, which further enhanced the degradation of pollutants. Consequently, the obtained micromotor demonstrated effective degradation of methylene blue and can be easily recovered by magnets. Furthermore, this simple and flexible strategy offers a synthetic way for anisotropic Janus particles, which will broaden their potential application.

Silver and gold nanoparticles biosynthesized by aqueous extract of burdock root, Arctium lappa as antimicrobial agent and catalyst for degradation of pollutants.

This study presents an efficient and facile method for biosynthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using aqueous extract of burdock root (BR), A. lappa, and their applications. The nanoparticles were characterized by ultraviolet-visible spectrophotometry, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, thermogravimetry, and differential thermal analysis. AgNPs capped the BR extract (BR-AgNPs) possessed roughly spherical geometry with an average diameter of 21.3nm while uneven geometry of AuNPs capped the BR extract (BR-AuNPs) showed multi shapes in average size of 24.7nm. The BR-AgNPs strongly inhibited five tested microorganism strains. In particular, the nanoparticles showed excellent catalytic activity for the conversion of pollutants within wastewater. Pseudo-first-order rate constants for the degradation of 4-nitrophenol, methyl orange, and rhodamine B were respectively found 6.77 × 10-3, 3.70 × 10-3, and 6.07 × 10-3s-1 for BR-AgNPs and 6.87 × 10-3, 6.07 × 10-3, and 7.07 × 10-3s-1 for BR-AuNPs. Graphical abstract ᅟ.

Biosynthesized AgNP capped on novel nanocomposite 2-hydroxypropyl-β-cyclodextrin/alginate as a catalyst for degradation of pollutants

This study presents an efficient and facile method for the trapping of Ag+ ions on hybrid nanocomposite based on 2-hydroxypropyl-β-cyclodextrin (HPCD) and alginate (Alg) in aqueous medium through ionotropic gelation mechanism and followed by in situ assembly of silver nanoparticles (AgNPs) using aqueous extract of Jasminum subtriplinerve leaves as a reducing agent. The nanocomposite AgNPs/HPCD/Alg was characterized by UV-vis, EDX, TEM, HR-TEM analysis. The AgNPs were found to be spherical shape and uniform size with an average diameter of 13.5 nm. EDX data showed about 4.0% (w/w) of AgNPs capped on the nanocomposite HPCD/Alg. The role of HPCD and Alg in the nanocomposites was observed from FTIR and thermal studies. The stability and distribution of the nanoparticles in the aqueous solution were determined by zeta potential and DLS measurements. The nanocomposites showed excellent catalytic performance for degradation of pollutants within industrial effluents including 4-nitrophenol, methyl orange and rhodamine B.

Facile synthesis of Fe3O4/MIL-101 nanocomposite as an efficient heterogeneous catalyst for degradation of pollutants in Fenton-like system

An active Fe3O4/MIL-101 hybrid material was prepared via a simple in situ solvothermal method and characterized as a heterogeneous Fenton-like catalyst for Rhodamine B (RhB) degradation.

Biofilm formation of a bacterial consortium on linuron at micropollutant concentrations in continuous flow chambers and the impact of dissolved organic matter

Bacterial multispecies biofilms are catalysts for pollutant degradation in aqueous ecosystems. Their activity in systems where xenobiotics occur as micropollutants (μg L(-1) level) and natural dissolved organic matter provides carbon and energy instead remains uncharacterized. Biofilm formation of a bacterial consortium consisting of the linuron-degrading Variovorax sp. WDL1 and metabolite-degrading strains Comamonas sp. WDL7 and Hyphomicrobium sp. WDL6 at micropollutant linuron concentrations and the impact of auxiliary carbon sources on degradation and biofilm composition were investigated. Biofilms formed at concentrations of 1000, 100, and 10 μg L(-1) linuron. The highest biomass, organized in mixed-species mounds, was observed at 1000 μg L(-1) linuron, while at 100 and 10 μg L(-1) , thin layers of cells occurred. Linuron removal efficiencies decreased from c. 85% when fed with 100 and 1000 μg L(-1) linuron to 30% in case of 10 μg L(-1) linuron due to reduced specific activity. Biofilms grown on 10 μg L(-1) linuron were subsequently fed with easily and less degradable carbon sources in addition to 10 μg L(-1) linuron. Although co-feeding with more degradable C-sources increased biofilm biomass, linuron removal remained 30%. Calculations based on biofilm volume measurements pointed toward reduced specific activity, compensated by a higher biomass. Uncertainties about biofilm heterogeneity and cell volume can undo this explanation.

Hierarchical Carbon Nanotube Membrane-Supported Gold Nanoparticles for Rapid Catalytic Reduction of p-Nitrophenol

Gold nanoparticles (AuNPs) have attracted increasing attention as catalysts for pollutant degradation because of their unique reactivity. Direct use of gold nanoparticles in water treatment faces prohibitive challenges from nanoparticle aggregation and post-treatment separation. To prevent nanoparticles from aggregating and eliminate the need for separation, we affixed AuNPs on hierarchical carbon nanotube membrane (HCNM) that was approximately 50 μm thin with 10 μm × 10 μm openings as pores for water passage. HCNM was fabricated by growing vertically aligned carbon nanotube (CNT) arrays on stainless steel mesh. Using p-nitrophenol (PNP) as model pollutant, we showed that in batch experiments HCNM-supported AuNPs retained 78% of their catalytic capability compared to suspended AuNPs. The slight reduction in reactivity was attributed to the blockage of part of the gold surface at the AuNP–CNT juncture. When the membrane was used in continuous flow-through operation, HCNM-supported AuNPs achieved 71% of the...