Decontamination Of Organic Pollutants Research Articles

Highly efficient and mild electrochemical degradation of bentazon by nano-diamond doped PbO2 anode with reduced Ti nanotube as the interlayer

Anodic oxidation based on PbO2 anode has been demonstrated as the feasible approach for the decontamination of organic pollutants; however, the performance of this process is hindered by its ordinary electrochemical activity and relatively low stability. In this study, we fabricated an efficient Ti/TiO2-RNTs/Sb-SnO2/PbO2-ND electrode with electrochemically reduced TiO2 nanotubes as the interlayer and nano-diamond as the dopant. As compared with other electrodes, the constructed Ti/TiO2-RNTs/Sb-SnO2/PbO2-ND exhibited higher oxygen evolution overpotential, larger active area and less charge transfer resistance. Thus, the average current efficiency of 30% could be attained at 120 min with TiO2-NTs/Sb-SnO2/PbO2, which was 1.5 times higher in comparison with the typical Ti/Sb-SnO2/PbO2 electrode. It was found that the removal efficiency of COD could be increased from 49% to 69% after 120 min treatment in the presence of 10 mM Cl−1 in the electrolyte. After 6 h of electrolysis, 74% of TOC was removed and 31% and 22% of initial N was transformed into NH4+ and NO3− ions, respectively. And oxalic acid, glyoxylic acid, malonic acid and acetic acid were identified quantitatively as the intermediate products. Finally, it was estimated that the accelerated service life of Ti/TiO2-RNTs/Sb-SnO2/PbO2-ND electrode was approximately three times of Ti/Sb-SnO2/PbO2 electrode. Generally, this study is of great interest for the engineering community to design an efficient electrode material for the wastewater treatment.

Catalytic degradation of ciprofloxacin by a visible-light-assisted peroxymonosulfate activation system: Performance and mechanism

Peroxymonosulfate (PMS) is extensively used as an oxidant to develop the sulfate radical-based advanced oxidation processes in the decontamination of organic pollutants and various PMS activation methods have been explored. Visible-light-assisted PMS activation to construct a Fenton-like process has shown a great potential for pollution control. In our work, BiVO4 nanosheets were prepared using a hydrothermal process and used to activate PMS under visible light. A rapid degradation of ciprofloxacin (CIP) was achieved by dosing PMS (0.96 g/L), BiVO4 (0.32 g/L) under visible light with a reaction rate constant of 77.72-fold higher than that in the BiVO4/visible light process. The electron spin resonance and free radical quenching experiments indicate that reactive species of •O2−, h+, •OH and SO4•− all worked, where h+, •OH and SO4•− were found as the dominant contributors to the CIP degradation. The spectroscopic analyses further demonstrate that the photoinduced electrons were directly involved in the PMS activation process. The generated •O2− was partially utilized to activate PMS and more •OH was produced because of the chain reactions between SO4•− and H2O/OH−. In this process, PMS acted as an electron acceptor to transfer the photo-induced charges from the conduction band of BiVO4 and PMS was successfully activated to yield the high-powered oxidative species. From the degradation intermediates of CIP detected by a liquid-chromatography-mass spectrometer, the possible degradation pathways were proposed. The substantially decreased toxicity of CIP after the reaction was also observed. This work might provide new insights into the visible-light-assisted PMS activation mechanisms and is useful to construct environmentally-friendly catalytic processes for the efficient degradation of organic pollutants.

Decontamination of organic pollutants from aqueous media using cotton fiber-graphene oxide composite, utilizing batch and filter adsorption techniques: a comparative study.

Cotton fiber–graphene oxide (C–GO) composite with high adsorptive properties towards the cationic dye, crystal violet (CV), was successfully fabricated by simple mixing of cotton fiber and GO in aqueous solution using a homogenizer. The as-prepared composite was characterized using TEM, SEM, LOM, XRD, FTIR, Raman and TGA. The characterization indicated that the formation of a homogeneous composite occurred via adequate mixing of the cotton fiber and GO. The fine structure of the obtained composite was successfully used in two adsorption techniques, namely batch adsorption and filter adsorption. Various parameters affecting batch adsorption, such as contact time, dye concentration, composite dose, NaCl dose, temperature and pH were investigated. In the filter adsorption mode, dye concentration, composite dose, NaCl dose, temperature, flow rate and pH were studied. A comparison study between the two techniques, i.e., batch adsorption and filter adsorption, are reported. The filter adsorption technique shows higher adsorption efficiency than the batch one, which was evident from the maximum adsorption capacity (Q°) values, obtained from the Langmuir isotherm. Further, the filter technique was developed and evaluated. This was achieved by regeneration, scaling-up and, finally, using another model of cationic dye (methylene blue).

Dendritic mesoporous carbon nanoparticles for ultrahigh and fast adsorption of anthracene

Developing highly effective adsorbents for efficient decontamination of organic pollutants from water is an evasive aim for community well-being and environmental protection. Here, we report the successful fabrication of dendritic mesoporous carbon nanoparticles (DMCNs) as an advantageous adsorbent for ultrahigh and fast adsorption of anthracene. Dendritic mesoporous organosilica nanoparticles with an octadecyl-rich framework were utilized to synthesize DMCNs through carbonization and removal of silica. The DMCNs show a high carbon content, large mesopore volume of 1.484 cm3 g−1 and high surface area of 1218 m2 g−1. It is revealed that both the high carbon content and highly accessible large surface area contribute to the excellent adsorption capacity towards anthracene (947.9 mg g−1), which is significantly higher than those in previous reports. Furthermore, the large radial pores of DMCNs with bimodal pore size distributions (2.1 and 18.4 nm) and open pore channels allow fast adsorption kinetics. The developed materials hold promise as effective adsorbents for efficient remediation of organic pollutants.

Protecting Enzymatic Activity via Zwitterionic Nanocapsulation for the Removal of Phenol Compound from Wastewater

Horseradish peroxidase (HRP) holds great potential in wastewater treatment. However, its instability in harsh environments remains a major issue. Various immobilization technologies were developed to retain enzyme stability at the cost of its effectiveness. We demonstrate that zwitterionic encapsulation of HRP retained both protein stability and activity to a large degree. In a water treatment study, encapsulating HRP into a zwitterionic nanogel resulted in a three-fold increase in the catalytic oxidation efficiency of phenol molecules. In addition, zwitterionic nanocapsules exhibited the best performance when compared with nanocapsules made from other hydrophilic polymers. These results indicated that zwitterionic HRP nanocapsules hold great potential in the decontamination of organic pollutants from wastewater.

Renewable biomass derived porous BCN nanosheets and their adsorption and photocatalytic activities for the decontamination of organic pollutants.

In this work, the preparation, characterization and removal capabilities of a novel biomass derived BC and its BCN nanocomposites are described. Possessing hierarchically porous structures, extremely large surface areas and special chemical bonds, porous BCN nanosheets have demonstrated advantages in terms of their adsorption and photocatalytic activities. The adsorption and photocatalytic activities of the as-prepared catalysts were evaluated by the degradation of RhB. The best results exhibited 97% and 95% decomposition of RhB which were obtained by using porous BCN-40 nanosheets within 120 min at 25 °C under UV light and visible light (>420 nm) irradiation respectively. The rate constant of the porous BCN-40 nanosheets for the degradation of RhB was more 16 times than that of pure h-BN. Besides, the porous BCN nanosheets showed remarkable cycling stability, maintaining a high photocatalytic activity up to 94% after 5 cycles. Furthermore, the degradation mechanisms of RhB and the photocatalytic mechanism have been explained in this paper.

A hybrid catalyst for decontamination of organic pollutants based on a bifunctional dicopper(II) complex anchored over niobium oxyhydroxide

This article describes the preparation and characterization of a hybrid oxidation catalyst for decontamination of organic pollutants which involves a bifunctional dicopper(II) complex and the niobium(V) oxyhydroxide as the active species, the later one being also a solid support. The pH range for the existence of the active species was determined by potentiometric and UV–vis spectroscopy at 25°C and 0.15M NaCl in a H2O/EtOH (70:30 v/v) solvent mixture containing copper(II) and the ligand N,Ń-2,2′-ethylenediphenylenebis(oxamic acid) (H4L). As far as the hybrid material is concerned, FTIR, FT-Raman, TEM and SEM images, surface area and TG/DTA analyses showed the occurrence of a chemical interaction between the dicopper(II) complex and the surface hydroxo groups of the niobium oxyhydroxide whereas ESI–MS and UV–vis spectroscopy evidence a total disappearance of the signals due to the organic dye which is used as model molecule. This hybrid material seems to combine the different properties of the components increasing its catalytic activity for oxidizing organic pollutants at different pH values.

Synthesis of MgO Nanoparticles from Different Organic Precursors; Catalytic Decontamination of Organic Pollutants and Antitumor Activity

The present work deals with the synthesis of nanostructured MgO from different organic precursors, by a facile precipitation method as catalysts for the decontamination of Malathion (stimulant of chemical warfare agents) (VX) and orange G as organic pollutants. The as-prepared nanoparticles were obtained by thermal decomposition of the oxalate, tartarate, citrate, succinate, malate, malonate and glycinate precursors at ≈650°C and were characterized by thermal analysis, FTIR, X-ray diffraction, high resolution transmission electron microscope (HRTEM) and absorption spectra. The morphology and crystal sizes were found to be highly affected by the starting organic precursors. The results revealed that the prepared inexpensive magnesium oxides have high potential as catalysts for photo degradation of both Malathion and orange G from water samples. Inhibitory activity against Breast Carcinoma MCF-7 cell line was detected using some selected nanosized MgO and compared to that of Vinblastine as a standard drug.

Activation of peroxymonosulfate with magnetic and recyclable Fe3 O4 @C/MnCo2 O4 nanocomposites for the decolorization of Acid Orange II

BACKGROUND Synthetic dyes present in wastewater from many industrial sections and they cause serious problems to human and aquatic life. The development of novel and effective peroxymonosulfate (PMS) activator is highly demanded in order to eliminate dyes pollution. In this regard, new magnetic nanocomposite Fe3O4@C/MnCo2O4 was prepared and characterized. The activity of Fe3O4@C/MnCo2O4 as heterogeneous catalyst for PMS activation was evaluated by the decolorization of Acid Orange II (AO II). RESULTS With “Fe3O4@C/MnCo2O4 + PMS” system, the dye solution could be nearly completely decolorized in about 25 min within a wide pH range (pH 4.1−8.1), and 98% removal could be achieved in 15 min without pH adjustment (pH = 6.38). The influences of solution pH, dosages of catalyst and PMS, reaction temperature, and PMS activation mechanism were studied. It was found that sulfate radicals were the primary species responsible for the oxidation of AO II. The catalyst was magnetically separable and displayed good stability and reusability for six cycles use without deterioration in its performance. CONCLUSION This study demonstrated the easy recycling and high activity of Fe3O4@C/MnCo2O4 composite in PMS activation for the decolorization of AO II solution. It supplies a promising way for the decontamination of organic pollutants.

Ultra-low loading of Ag3PO4 on hierarchical In2S3 microspheres to improve the photocatalytic performance: The cocatalytic effect of Ag and Ag3PO4

Ag3PO4/In2S3 composite photocatalysts with ultra–low loading of Ag3PO4 (0.017 ∼ 4.89wt %) were prepared by a facile precipitate method and characterized by XRD, SEM, TEM, HRTEM, BET, DRS and XPS techniques. The as–obtained composites were employed to degrade different kinds of organic pollutants (dyes and colorless pollutants) in aqueous solution under visible light irradiation. The Ag3PO4/In2S3 composites exhibited excellent adsorption capacity and photocatalytic activity. The optimal composite with 0.086wt % Ag3PO4 content exhibited the highest photocatalytic activity, which could degrade almost all dyes (MO, MB and RhB) within 7min of light irradiation and more than 50% of phenol and salicylic acid after 3h of irradiation. Recycling experiments confirmed that the Ag3PO4/In2S3 catalysts had superior cycle performance and structural stability. The photocatalytic activity enhancement of Ag3PO4/In2S3 composites could be mainly attributed to the efficient separation of photogenerated charge carriers through a Z–scheme system composed of Ag3PO4, Ag and In2S3, in which Ag nanoparticles acted as the charge transmission bridge. The high photocatalytic stability was ascribed to the successful inhibition of the photocorrsion of both In2S3 and Ag3PO4 by transferring the photogenerated holes and electrons from them to Ag, respectively. This study indicated the application of Ag–Ag3PO4 as cocatalyst and provided a new way to design and prepare high–efficiency and stable photocatalysts for photocatalytic decontamination of organic pollutants.

Facile synthesis of hierarchical Mo-doped S/BiOCl heterostructured spheres and its excellent photo/thermocatalytic activity under near room temperature

Hierarchical Mo-doped S/BiOCl (MSB) heterostructures were successfully prepared by a facile one-step reflux method. The resulting samples were evaluated by XRD, SEM, TEM, DRS and XPS. The results obtained showed that MSB possessed an outstanding photo and/or thermocatalytic performance under near room-temperature for removal of methylene blue (MB), reaching up to 99.9 and 96.5% for photo/thermocatalytic degradation (PTD) and thermocatalytic degradation (TD), respectively. The hole/radical scavenger tests indicated holes and free radial were both participated in PTD and TD reactions, but the holes formed from degradation reactions were strongly considered as the most influential impact on conducting PTD and TD patterns rather than free radicals. Furthermore, the kinetics regarding PTD and TD routes were also monitored, preferentially fitting to Langmuir–Hinshelwood behavior. Briefly, this study may provide new insights into fabricating hierarchical heterostructures by in-suit one-step approach for decontamination of organic pollutants separately using PTD or TD.

Dual Effect of Manganese Oxide Micromotors: Catalytic Degradation and Adsorptive Bubble Separation of Organic Pollutants.

Manganese oxide (MnO2 ) based micromotors exhibiting a dual effect, that is, catalytic degradation and adsorptive bubble separation, were employed for water remediation. The dual effect of MnO2 microparticles led to a greater than 90 % of decolorization of non-biodegradable organic dyes in just 1 h, without the need for external agitation or bubble generation. These findings suggest high potential of MnO2 micromotors for decontamination of organic pollutants from wastewaters or natural water reserves.

Adsorption of organic pollutants by surfactant modified zeolite as controlled by surfactant chain length

Surfactant modified zeolites are promising for decontamination of organic pollutants from water. However, the influence of chain length of surfactants on decontamination process has not been clarified to our knowledge. In this study, a natural zeolite was modified with surfactants of varying chain length (from one carbon to 22 carbons) and the adsorption of organic contaminants, including anionic (sodium form of humic acid), ionizable (phenol, p-chlorophenol and bisphenol A), and non-ionizable compounds (naphthalene) was investigated. Results showed that the amount of surfactant loaded increased with increasing chain length. Measurement of FTIR spectroscopy indicated that the surfactant chains adopted a more disordered conformation as the chain length decreases. In general, the adsorption of the organic pollutants increases as the chain length increases. We noted that long chain length, high surfactant coverage, and ordered chain conformation are driving forces for the retention of organic chemicals. The pH dependency of adsorption suggested that negatively charged groups of anionic or ionizable organic solutes interacted with positively charged head of surfactant. Furthermore, adsorption increased with increasing kow value for organic pollutants, indicating that hydrophobic interaction of the benzene ring(s) of organic compounds with the carbon chain of surfactant contributes to adsorption.

Photochemical Coupling of Iron Redox Reactions and Transformation of Low-Molecular-Weight Organic Matter

The photoreactions between Fe(III)/Fe(II) and low-molecular-weight organic matter (LMWOM) under solar irradiation have significant implications for many biogeochemical cycles on the Earth and for the fates of environmental pollutants. In this Perspective, we focus on several fundamental aspects of the photochemical processes that couple the redox cycling of iron species and transformation of organic substrates. The primary photoprocesses (e.g., intramolecular electron transfer or photodissociation) are first highlighted by introducing the recently disputed observations on the photolysis of ferrioxalate complexes. The effects of LMWOM and its daughter radicals on the photochemical redox cycling of iron species are discussed with special attention given to the example of Fe–malonate complexes. These processes and mechanisms would provide us some refreshed understanding of environmental photochemistry of LMWOM and the iron species and would be helpful for our assessment of photochemical decontamination of organic pollutants.

Preparation, properties and applications of polysaccharide nanocrystals in advanced functional nanomaterials: a review

Intensive exploration and research in the past few decades on polysaccharide nanocrystals, the highly crystalline nanoscale materials derived from natural resources, mainly focused originally on their use as a reinforcing nanophase in nanocomposites. However, these investigations have led to the emergence of more diverse potential applications exploiting the functionality of these nanomaterials. Based on the construction strategies of functional nanomaterials, this article critically and comprehensively reviews the emerging polysaccharide nanocrystal-based functional nanomaterials with special applications, such as biomedical materials, biomimetic optical nanomaterials, bio-inspired mechanically adaptive nanomaterials, permselective nanostructured membranes, template for synthesizing inorganic nanoparticles, polymer electrolytes, emulsion nano-stabilizer and decontamination of organic pollutants. We focus on the preparation, unique properties and performances of the different polysaccharide nanocrystal materials. At the same time, the advantages, physicochemical properties and chemical modifications of polysaccharide nanocrystals are also comparatively discussed in view of materials development. Finally, the perspective and current challenges of polysaccharide nanocrystals in future functional nanomaterials are outlined.

Continuous flow photochemical reactor for solar decontamination of water using immobilized TiO 2

A photochemical reactor is designed for solar decontamination of organic pollutants in water, where the nanocrystalline photocatalyst TiO 2 is immobilized on glass. The reactor modules could be connected in series and/or parallel to achieve desired flow rates under different conditions of illumination and degree of contamination. Methyl violet and phenol was found to completely degrade under solor irradiation and flow rates of 102–138 ml/h.