Organic Pollutants In Water Research Articles

Effect of synthesis methodologies upon the photocatalytic performance of Bi0.5Na0.5TiO3 for pollutant degradation.

In the face of mounting environmental concerns, we must seek out innovative solutions for remediation. Using nanomaterials to degrade organic pollutants in water under ambient visible light holds great promise as a safe, cost-efficient, and effective approach to addressing pollution in our water bodies. The development of novel materials capable of such pollution degradation is desired to preserve the environment. In this study, Bi0.5Na0.5TiO3 (BNT) nanoparticles are synthesized through hydrothermal and solid-state routes, and their physicochemical properties are compared to assess their photocatalytic performance. The results of the characterization studies indicate that the hydrothermally synthesized nanoparticles outperformed the solid-state synthesized counterparts in terms of photocatalytic performance. The photocatalytic degradation of Rhodamine blue dye under ambient light exposure is examined at various dye concentrations and catalyst dosages. BNT nanoparticles demonstrated excellent photocatalytic properties, stability, and recyclability, making them a promising candidate for various photocatalytic applications. The findings of this study could pave the way for the development of sustainable and environmentally friendly photocatalytic technologies for water remediation.

Comparative study of visible-light active BiOI and N,Pd-TiO2 photocatalysts: Catalytic ozonation for dye degradation

The increasing demand for clean water requires the development of simple, cheap, and efficient catalysts systems for water pollution remediation. To develop cheap yet efficient hybrid advanced oxidation processes for degradation of organic pollutants in water requires their systematic comparison under similar conditions to make informed decisions of economically feasible and sustainable systems. Visible light active single BiOI and N, Pd co-doped TiO2 were investigated for photocatalytic ozonation (PCO) for methylene blue (MB) degradation. Metal and non-metal co-doping improved morphology, band structure and active sites on the surface of TiO2 to shift its light absorption into the visible region. The degradation of MB with BiOI PCO and N,Pd-TiO2 PCO was practically similar but showed improvement of the ozonation mineralization efficiency. However, mineralization of MB on BiOI PCO surpassed that of N,Pd-TiO2 PCO due to band structure that influenced generated free radicals during the PCO processes. BiOI PCO system progressed through the existence and involvement of strongly oxidizing and non-selective hydroxyl radicals towards enhanced mineralization of dye and intermediates while N,Pd-TiO2 PCO was steered by the superoxide radical that is selective and had lower mineralization efficiency of formed intermediates despite its high initial degradation efficacy. The work demonstrated cheap and efficient visible light active semiconductors like BiOI as potential candidates for application in photocatalytic ozonation for real applications with matching activities to that of co-doped UV active semiconductors like TiO2. This work advances the use of visible light active semiconductors towards PCO based processes for environmental pollution remediation.

Enhanced photocatalytic degradation of organic pollutants in water using copper oxide (CuO) nanosheets for environmental application

Rapid, inexpensive, and low-power/solar light-driven photocatalytic degradation of organic pollutants to deal with annually produced trillion tons of synthetic dye wastewater to prevent water scarcity issues, ecotoxicological risks, and human health has always been challenging. To overcome this limitation, the present study synthesized earth-abundant, inexpensive copper oxide nanosheets using a simple single-step hydrothermal route. The structural, physicochemical, and functional properties of the nanosheets have been characterized using several characterization techniques. The photocatalytic activity was studied for two commonly industrially used organic dyes, Methylene Blue (MB) and Rhodamine B (RhB). The importance of this work is the usage of a cheap commercially available Phillips UV light (11 W) as well as direct sunlight. With several optimized conditions, almost complete degradation of both dyes was achieved within 35 minutes under low-power UV light and within 70 minutes by the direct illumination of natural sunlight. The enhanced photocatalytic performance can be correlated to the synergetic effect of a higher charge transfer mechanism, good catalytic ‘active surface area’ availability (13.2 m2/g), and several optimized parameters that affect the reaction efficacy. Additionally, five repeated uses of nanosheets without sacrificing performance confirmed their stability and sustainability as a promising candidate for large-scale industrial textile wastewater remedies.

Silver nanoparticles decorated polydopamine-coated pure silica zeolite as an efficient nanocatalyst for organic pollutants removal

An efficient catalyst, composed of silver-decorated polydopamine coatings on pure silicon zeolite (PSZN/PDA/Ag), capable of removing organic pollutants in water effectively, was synthesized using an economical in-situ reduction approach. The polydopamine (PDA) coating facilitates the stable dispersion of silver (Ag) nanoparticles and offers numerous catalytic active sites. This can be attributed to the ability of PDA in acting as a redox medium, via the interchange between its catechol group and the benzoquinone structure, thereby decreasing impediments to electron transfer among reactants, and consequently promoting the catalytic reaction. The porous structure of PSZN aids in embedding the PDA elements inside the pores, preventing the coating from peeling off and providing additional adsorption to transport reactants to the catalytic center for cooperative catalysis. Leveraging these properties, it demonstrates excellent efficiency and reusability in the catalytic reduction of waste methylene blue (MB) and 4-nitrophenol (4-NP), achieving reaction rates of 41.23 × 10-2 min−1 across five cycles respectively, with a minimum average conversion rate of 96 %. Moreover, the impressive performance is primarily due to the significant load (wt = 30.7 %) and small size (11.85 nm) of Ag nanoparticles, which boast a large number of reaction centers.

Ultrasonic-assisted adsorption of heavy copper and lead metal ions by g-C3N4, application of g-C3N4@MNPs (M: Pb, Cu) in the catalytic photoreduction of organic pollutants

In this paper, the prepared g-C3N4 was used firstly as an adsorbent of copper and lead ions by using both ultrasonic and classical methods in order to improve the adsorption of bigger metal amounts in a very good dispersion. This adsorption study was performed in-depth by evaluating the influence of contact time, the metal concentration, and the pH effect. The adsorption mechanism follows the Langmuir isotherm and the pseudo-second-order model which confirm its chemisorption type. The maximal adsorbed quantities obtained were 285.7 mg/g and 238.09 mg/g for Cu2+ and Pb2+ respectively which represent a high performance. Once the adsorption was done, the obtained nanocomposite g-C3N4@CuNPs and g-C3N4@PbNPs were used in the photocatalytic reduction of anionic and cationic dye in a simple and binary system which constitutes a recovery and recycling of heavy metals. All materials were characterized by several analyses in order to investigate the structural, thermal, textural, and morphological properties. Each nanocomposite showed an affinity for a specific material according to its surface charge. Finally, the rate constants towards methylene blue dye reached a high level up to 1.2881 min−1 and 0.6406 min−1 for the g-C3N4@CuNPs and g-C3N4@PbNPs respectively, implying a large efficiency against both organic and inorganic water pollutants.

Dual defect regulation of BiOCl halogen layer enables photocatalytic O2 activation into singlet oxygen for refractory aromatic pollutant removal

The generation of singlet oxygen (1O2) based on photocatalytic activation O2 is considered to have important application prospects in purifying refractory organic pollutants in water. However, the uncertain dual pathway transformation of activated O2 severely limits the generation of 1O2. In this work, we show a robust BiOCl with dual defects (adjacent I-substitution defect and Cl vacancy) in halogen layer for the selective activation of O2 to generate 1O2. Combining experiments and theoretical calculations, we confirm that dual defects are beneficial in optimizing band structures, improving carrier separation efficiency, and promoting O2 adsorption and activation. More importantly, it is confirmed that dual defects can directionally convert O2 into 1O2 by increasing the thermodynamic conversion energy barrier of non-1O2 conversion pathways and serving as a necessary site for 1O2 generation with dual functions of oxidation and reduction. Applying dual defect modified BiOCl to the removal of refractory aromatic pollutants in water, it is found that it has efficient and stable photocatalytic degradation efficiency and broad environmental adaptability. This work not only provides in-depth insights into the mechanism of photocatalytic activation of O2 to selective produce 1O2, but also lays the foundation for further development of highly active photocatalysts for environmental remediation and energy conversion.

Surface functionalization of a chalcogenide IR photonic sensor by means of a polymer membrane for water pollution remediation.

Rapid, simultaneous detection of organic chemical pollutants in water is an important issue to solve for protecting human health. This study investigated the possibility of developing an in situ reusable optical sensor capable of selective measurements utilizing a chalcogenide transducer supplemented by a hydrophobic polymer membrane with detection based on evanescent waves in the mid-infrared spectrum. In order to optimise a polyisobutylene hydrophobic film deposited on a chalcogenide waveguide, a zinc selenide prism was utilized as a testbed for performing attenuated total reflection with Fourier-transform infrared spectroscopy. To comply with the levels mentioned in health guidelines, the target detection range in this study was kept rather low, with the concentration range extended from 50 ppb to 100 ppm to cover accidental pollution problems, while targeted hydrocarbons (benzene, toluene, and xylene) were still detected at a concentration of 100 ppb. Infrared measurements in the selected range showed a linear behaviour, with the exception of two constantly reproducible plateau phases around 25 and 80 ppm, which were observable for two polymer film thicknesses of 5 and 10 μm. The polymer was also found to be reusable by regenerating it with water between individual measurements by increasing the water temperature and flow to facilitate reverse exchange kinetics. Given the good conformability of the hydrophobic polymer when coated on chalcogenide photonic circuits and its demonstrated ability to detect organic pollutants in water and to be regenerated afterwards, a microfluidic channel utilising water flow over an evanescent wave optical transducer based on a chalcogenide waveguide and a polyisobutylene (PIB) hydrophobic layer deposited on its surface was successfully fabricated from polydimethylsiloxane by filling a mold prepared via CAD and 3D printing techniques.

Zinc-doped C4N3/BiOBr S-scheme heterostructured hollow spheres for efficient photocatalytic degradation of tetracycline.

Photocatalytic degradation of organic pollutants in water is of great significance to the sustainable development of the environment, but encounters limited efficiency when a single compound is used. Thus, there have been enormous efforts to find novel photocatalytic heterostructured composites with high performance. In this work, a novel S-scheme heterostructure is constructed with BiOBr and Zn2+ doped C4N3 (Zn-C4N3) by a solvothermal method for efficient photodegradation of tetracycline (TC), a residual antibiotic difficult to be removed from the aquatic environment. Thanks to Zn2+-doping induced improvement in chemical affinity between Zn-C4N3 and BiOBr, well-formed Zn-C4N3/BiOBr heterostructured hollow spheres are formed. This structure can efficiently suppress fast recombination of photogenerated electron-hole pairs to enhance the photocatalytic activity of BiOBr dramatically. At a room temperature of 25 °C and neutral pH 7, the catalyst can degrade a significant portion of TC pollutants within 30 min under visible light. Also, the Zn-C4N3/BiOBr heterostructure displays good stability after recycling experiments. Free radical capture experiments and ESR tests show that ˙O2- is the main active substance for photocatalytic degradation of TC. This study provides new insights for constructing heterostructures with an intimate interface between the two phases for photocatalytic applications.

Synergistically enhanced photoelectrocatalytic degradation of ciprofloxacin via oxygen vacancies and internal electric field on a NiSe2/WO3 photoanode

This study presents the in situ deposition of nickel selenide (NiSe2) on tungsten trioxide (WO3) nanorods to enhance the photoelectrocatalytic degradation of organic pollutants in water.

Characteristics of Fe/C catalysts based on pyrolysis of ferric citrate and its peroxymonosulfate activation performance to degrade sulfadiazine in water.

Advanced oxidation techniques based on peroxysulfate activation have been paid much attention owing to their excellent performance in degrading stubborn pollutants in water. In response to the current situation that requires more raw materials and higher costs and involves more complicated processes for the preparation of Fe/C catalysts to activate persulfates, novel catalysts (Fe/C-700, Fe/C-800, Fe/C-900 and Fe/C-1000) were prepared by a high-temperature carbonization method at different pyrolysis temperatures (700, 800, 900 and 1000 °C) using inexpensive and environmentally friendly ferric citrate as raw material. Fe/C catalysts were characterized using SEM, EDS, XRD, XPS, and VSM and were screened for the activation of peroxymonosulfate (PMS) to degrade sulfadiazine (SDZ) in water, where Fe/C-900 exhibited higher efficiency. Thus, its activation performance for PMS to degrade SDZ was comprehensively investigated and the mechanisms of activation degradation were analyzed. The results showed that the degradation rate of 98.7% can be achieved to 10 mg L-1 SDZ by 0.1 g L-1 Fe/C-900 and 0.5 mmol L-1 PMS within 60 min. A wide range of solution pH, low catalyst dosage and good recycling performance were found in the Fe/C-900 application and the amount of iron ions dissolved at the end of the reaction was low (0.350 mg L-1). It was shown that both free radical and non-free radical pathways existed in the reaction system, where 1O2, SO4-˙ and O2-˙ played dominant roles in the degradation process of SDZ. The results could provide new ideas for the preparation of Fe/C catalysts and their heterogeneous activation for PMS to degrade stubborn organic pollutants in water.

Solid-waste-recycled CuO/C3N4 S-scheme heterojunctions for efficient photocatalytic antibiotic degradation.

With the increasing severity of antibiotic pollution, the development of effective green photocatalysts for the degradation of organic pollutants in water has attracted extensive attention. Herein, we have prepared CuO/C3N4 S-scheme heterogeneous photocatalysts via recycling Cu resources from Cu-containing electroplating sludges. By mediating the acid leaching process, copper in electroplating sludges was dissolved selectively, while other metal species were retained in the residues. The CuO/C3N4 S-scheme heterojunction not only effectively suppressed the recombination of photogenerated charge carriers of C3N4, but also preserved the strong reducing electrons of C3N4 and the strong oxidizing holes of CuO, retaining the outstanding redox ability of CuO/C3N4. Therefore, CuO/C3N4 photocatalysts exhibited good catalytic performance in the degradation of tetracycline (over 95% in 2 h). In addition, CuO/C3N4 S-scheme heterojunctions achieved a high mineralization rate (45% in 2 hours), thus reducing secondary pollution during the degradation. This work provides a reliable direction for designing novel S-scheme heterojunction photocatalytic materials by using metal sources in solid waste.

Interfacial engineering of a multijunctional In2O3/WO3@Ti4N3Tx S-scheme photocatalyst with enhanced photoelectrochemical properties.

Achieving high photoelectrochemical conversion efficiency requires the logical layout of a composite photocatalyst with optimal charge separation and transfer with ideal light harvesting capabilities to enhance the photocatalytic performance and the degradation rate towards organic pollutants. Herein, a novel In2O3/WO3@Ti4N3Tx S-scheme heterojunction was successfully synthesized and confirmed through valence band VB-XPS and Mott Schottky combined analysis. The formed MXene-doped In2O3/WO3@Ti4N3Tx S-scheme significantly enhances the charge flow and spatial separation with an improved oxidation and reduction ability. An in-built interfacial electric field at the WO3-In2O3 boundary enhanced the light-harvesting capacity, whereas Ti4N3Tx MXene offers a unique electron trapping effect which effectively lowers high charge carrier recombination rate-related photocatalytic deficit. It preserves the exceptional redox potency of the photocatalyst by providing a directed acceleration and effective separation of the photogenerated charges. A high carrier density (ND = 7.83 × 1021 cm-3) with a lower negative flat band (VFB = -0.064 V vs. Ag/AgCl) was obtained by Mott-Schottky analysis for 3 wt% In2O3/WO3@Ti4N3Tx, an indicator that a low overpotential is needed to activate photocatalytic reactions. This study, therefore, provides a novel thought for the design and fabrication of an S-scheme heterojunction for photocatalytic reactions for mineralization of organic pollutants in water and clean energy production.

Hydrodynamic Cavitation Enhanced SR-Aops Degradation of Organic Pollutants in Water: A Review

Hydrodynamic Cavitation Enhanced SR-Aops Degradation of Organic Pollutants in Water: A Review

Peroxymonosulfate activation by CuMn-LDH for the degradation of bisphenol A: Effect, mechanism, and pathway

The remediation of water contaminated with bisphenol A (BPA) has gained significant attention. In this study, a hydrothermal composite activator of Cu3Mn-LDH containing coexisting phases of cupric nitrate (Cu(NO3)2) and manganous nitrate (Mn(NO3)2) was synthesized. Advanced oxidation processes were employed as an effective approach for BPA degradation, utilizing Cu3Mn-LDH as the catalyst to activate peroxymonosulfate (PMS). The synthesis of the Cu3Mn-LDH material was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). According to the characterization data and screening experiments, Cu3Mn-LDH was selected as the best experimental material. Cu3Mn-LDH exhibits remarkable catalytic ability with PMS, demonstrating good degradation efficiency of BPA under neutral and alkaline conditions. With a PMS dosage of 0.25 g·L−1 and Cu3Mn-LDH dosage of 0.10 g·L−1, 10 mg·L−1 BPA (approximately 17.5 μM) can be completely degraded within 40 min, of which the TOC removal reached 95%. The reactive oxygen species present in the reaction system were analyzed by quenching experiments and EPR. Results showed that sulfate free radicals (SO4•—), hydroxyl free radicals (•OH), superoxide free radicals (•O2—), and nonfree radical mono-oxygen were generated, while mono-oxygen played a key role in degrading BPA. Cu3Mn-LDH exhibits excellent reproducibility, as it can still completely degrade BPA even after four consecutive cycles. The degradation intermediates of BPA were detected by GCMS, and the possible degradation pathways were reasonably predicted. This experiment proposes a nonradical degradation mechanism for BPA and analyzes the degradation pathways. It provides a new perspective for the treatment of organic pollutants in water.

Porphyrin-containing materials for photodegradation of organic pollutants in wastewaters: a review

Industrialization and town urbanization have led to an exponential need for clean water and new wastewater treatment strategies.

Greening the waves: experimental and chemometric approaches in spectroscopic methods for organic pollutant determination in natural waters

The review paper explores new experimental and chemometric methods in spectroscopy for detecting organic pollutants in natural waters, aiming to improve sustainability and monitoring accuracy.

Global monitoring of persistent organic pollutants (POPs) in biota, water and sediments: its role in screening for unregulated POPs, in compiling time trends of regulated POPs under the Stockholm Convention (SC) and their relevance for biodiversity in a changing climate

This paper considers elements of the dynamic process of production dispersal and monitoring of persistent organic pollutants in the environment that has unfolded over the past 100 years.

Nitrogen-rich cobalt metal–organic framework as a heterogeneous catalyst for the degradation of organic dye pollutants in water via peroxymonosulfate activation

A Co3-btca heterogeneous catalyst can activate PMS to efficiently degradate organic dyes rhodamine B and methyl violet in water.

Donor–acceptor hetero[6]radialene-based three-dimensional covalent organic frameworks for organic pollutant adsorption, photocatalytic degradation, and hydrogen production activity

By investigating the effects of electron donor topology and the hetero[6]radialene structure on the 3D COF photocatalytic activity, a twisted BF structure was found to improve organic pollutant degradation and water hydrogen production.

Elucidating the role of the nanostructure in protein aerogels for removal of organic water pollutants

Access to efficient and affordable materials for water purification is of fundamental importance for the sustainable development of our society. Materials based on protein nanofibrils (PNFs) from agricultural waste- or...