Degradation Of P-nitrophenol Research Articles

Unlocking high-efficiency decontamination by building a novel heterogeneous catalytic reduction system of thiourea dioxide/biochar

Herein, we reported a new contaminant purification paradigm, which enabled highly efficient reductive denitration and dechlorination using a green, stable reducing agent thiourea dioxide (TDO) coupled with biochar (BC) over a wide pH range under anoxic conditions. Specifically, BC acted as both activators and electron shuttles for TDO decomposition to achieve complete anoxic degradation of p-nitrophenol (PNP), p-nitroaniline, 4-chlorophenol and 2,4-dichlorophenol within 2 h. During this process, multiple strongly reducing species (i.e., SO22-, SO2•- and e-/H•) were generated in BC/TDO systems, accounting for 13.3%, 9.7% and 75.5% of PNP removal, respectively. While electron transfer between TDO and H+ or contaminants mediated by BC led to H• generation and contaminant reduction. These processes depended on the electron-accepting capacity and electron-conducting domains of biochar. Significantly, the BC/TDO systems were highly efficient at a pH of 2.0–8.0, especially under acidic conditions, which performed robustly in common natural water constituents.

Preparation of biochar-loaded nano zero-valent iron electrode material and its electrocatalytic degradation of p-nitrophenol

<p>Electrochemical treatment of wastewater containing p-nitrophenol (PNP) was carried out using a platinum electrode as an anode and biochar-loaded nano zero-valent iron material as the cathode. The prepared biochar loaded nano zero valent iron electrode materials were characterized and analyzed using SEM, XRD, and XPS. The experiment investigated the effects of current density, initial PNP concentration, electrolyte concentration, pH value, and other factors on the treatment effect of PNP. The results showed that the nZVI/BC electrode with an initial pH value of 7.0, a current density of 10mA/cm2, and an electrolyte of 1.5g/L anhydrous sodium sulfate was the optimal condition for degrading a PNP solution with an initial concentration of 20 mg/L. The PNP removal rate within 24 hours was 81.94%.BC@nZVI electrode has good stability and reusability.</p>

Interfacial engineering of BiVO4/PANI p-n heterojunction for enhanced photocatalytic degradation of p-nitrophenol: Pathway, toxicity evaluation and mechanistic insights

The presence of organic micro-pollutants (OMPs) in the water sources is a major threat to the aquatic and human health and also affects the wastewater treatment process. p-Nitrophenol (p-NP), has been extensively used as raw materials in various chemical industries. The present study focused on the development of BiVO4/PANI nanocomposites (NCs) for enhanced photocatalytic degradation of p-NP under visible light irradiation. The morphology, chemical composition and crystallinity of the prepared NCs was characterized by XRD, XPS, FE-SEM, RAMAN, EIS and TEM, and the optical properties of the NCs were determined by UV–vis DRS, and PL analysis. Compared to the bare BiVO4 and PANI, the NCs showed a better performance against p-NP (98.25 %) and had good cycle stability (91.91 % after six cycles). The enhance photocatalytic performance of the NCs is ascribed to the synergistic effect and the p-n heterojunction formed between BiVO4 and PANI. Furthermore, several tests were done to determine the effect of pH, NCs and p-NP concentrations and influence of various ions were also studied. Scavenger experiments revealed that •OH, and h+ contributed significantly in the degradation process of p-NP. The intermediate metabolites were identified, and toxicity of the by-products was elucidated by using GC–MS and ECOSAR program respectively. The reusability of the material was assessed by repeating the degradation experiment for 6 consecutive cycles. This work underlines the promising potential of BiVO4/PANI NCs for efficient treatment of toxic pollutants bearing wastewater.

In-situ growth of Mn-Ni3S2 on nickel foam for catalytic ozonation of p-nitrophenol

In this study, a new catalyst for catalytic ozonation was obtained by in-situ growth of Mn-Ni3S2 nanosheets on the surface of nickel foam (NF). The full degradation of p-nitrophenol (PNP) was accomplished under optimal conditions in 40 min. The effects of material dosage, ozone dosage, pH and the presence of inorganic anions on the degradation efficiency of PNP were investigated. ESR analysis showed that singlet oxygen (1O2) and superoxide radical (O2•-) are the main contributors of PNP degradation. This study offers a new combination of supported catalysts with high efficiency and easy recovery, which provides a new idea for wastewater treatment.

Effect of pH on the ozonolysis degradation of p-nitrophenol in aquatic environment and the synergistic effect of hydroxy radical.

Density functional theory (DFT) was employed to elucidate the mechanisms for ozonolysis reaction of p-nitrophenol (PNP) and its anion form aPNP. Thermodynamic data, coupled with Average Local Ionization Energies (ALIE) analysis, reveal that the ortho-positions of the OH/O- groups are the most favorable reaction sites. Moreover, rate constant calculations demonstrate that the O3 attack on the C2-C3 bond is the predominant process in the reaction between neutral PNP and O3. For the aPNP + O3 reaction, the most favorable pathways involve O3 attacking the C1-C2 and C6-C1 bonds. The rate constant for PNP ozonolysis positively correlates with pH, ranging from 5.47 × 108 to 2.86 × 109M-1s-1 in the natural aquatic environment. In addition, the formation of hydroxyl radicals in the ozonation process of PNP and the mechanisms of its synergistic reaction of PNP with ozone were investigated. Furthermore, the ozonation and hydroxylation processes involving the intermediate OH-derivatives were both thermodynamically and kinetic analyzed, which illustrate that OH radicals could promote the elimination of PNP. Finally, the toxic of PNP and the main products for fish, daphnia, green algae and rat were assessed. The findings reveal that certain intermediates possess greater toxicity than the original reactant. Consequently, the potential health risks these compounds pose to organisms warrant serious consideration.

Photocatalytic degradation of p-nitrophenol using carbon microspheres loading Cu0 activation of peroxymonosulfate

Photocatalytic degradation of p-nitrophenol using carbon microspheres loading Cu0 activation of peroxymonosulfate

Unexpectedly enhanced degradation of acetaminophen by sulfoxides probe in Fe(II)-activated persulfate oxidation: The mechanism and the selectivity

Sulfoxides are widely recognized as probes for identifying and evaluating the generation and contribution of high-valent metals in advanced oxidation processes. However, this paper was surprising to find that the presence of sulfoxides selectively enhanced the degradation of specific pollutants in the Fe(II)/PS system. Represented by methyl phenyl sulfoxide (PMSO), scavenging experiments for active species showed that the presence of PMSO transformed the mechanism from radical dominated (55.60 %) to nonradical dominated (60.91 %), greatly improving the anti-interference ability of the system. Determining the concentration of Fe(Ⅱ) and total iron (Fetot) in solution revealed that the presence of PMSO improved the utilization efficiency of Fe(II) and PS by enhancing the redox reaction between Fe(II) and PS, and resulted in the generation of Fe(IV) more favorably than the generation of SO4·− and ·OH. Additionally, comparing the proven high-valent iron dominated Fe(II)/PI system with the free radical dominated Fe(II)/PS system of this paper, it was revealed that the selectively enhanced oxidation of PMSO specifically targets the free radical dominated system. Experiments have shown that the degradation of acetaminophen, ibuprofen, phenol, and p-chlorophenol was enhanced by PMSO, while the degradation of norfloxacin, primidone, chloramphenicol, sulfamethoxazole, p-nitrophenol, benzoic acid, and nitrobenzene was inhibited. Based on density functional theory (DFT) calculations, PMSO has a selectively enhanced degradation effect for organic pollutants with ionization potential (IP) below 8.66 eV, and vice versa, it has an inhibitory effect. The present study provides new insights into the contribution of sulfoxide to the assessment of high-valent metals and sheds new light on the mechanism of active species.

Anti-perovskite Co4N nanowhisker rooted on nickel foam to activate peroxymonosulfate for robust degradation of p-nitrophenol via non-radical dominant pathway

The fabrication of metal-nitrogen functional centers that possess features of easy recovery and high performance for degrading organic pollutants through activating peroxymonosulfate (PMS) represents a significant challenge. In this study, we present the synthesis of an anti-perovskite Co4N architecture in a granular nanowhisker form rooted on three-dimensional nickel foam (Co4N/NF) using a hydrothermal method followed by thermal nitridation with ammonia from urea pyrolysis. The resulting Co4N/NF exhibits exceptional efficiency in degrading p-nitrophenol (PNP), achieving a degradation efficiency of 97.8 % and a rate constant of 0.204 min−1 within 20 min. The unique nanostructure of granular nanowhisker Co4N on NF provides abundant surface sites for activating PMS and enhances mass/electron transport, contributing to its excellent degradation capabilities. Additionally, the Co4N/NF material exhibits outstanding stability, easy separation and recovery features, maintaining a degradation efficiency of 90.2 % within 20 min even after five cycles. This study lays the groundwork for developing advanced anti-perovskite nitrides on a 3D substrate to activate PMS for environmental contaminant remediation.

Rational construction of defect-enriched α-Fe2O3/Bi2S3 composites for high-effective photocatalytic degradation of p-nitrophenol

Herein, the high-activity α-Fe2O3 (PSNF) was obtained first, and defect-enriched PSNF/Bi2S3 composites were prepared via a one-step hydrothermal process. The obtained PSNF had abundant oxygen vacancies (OV) and low bandgap energy, showing enhanced visible-light catalytic activity. Compared with PSNF and Bi2S3, the PSNF/Bi2S3 composites presented superior adsorption capacity and photocatalytic degradation activity for p-nitrophenol (p-NP). The p-NP degradation process followed the BMG model. The PSNF/Bi2S3-2 exhibited the highest photocatalytic activity, as 90.5% of the p-NP was degraded within 30 min. A tight heterojunction was formed between PSNF and Bi2S3 by the S–O bond, which effectively inhibited the recombination of photoproduced carriers and promoted the generation of OV defects. Under the synergistic effect of OV detects, photo-Fenton, and heterojunction, the generation of active species was promoted in the composite degradation system, thereby resulting in the rapid degradation of p-NP.

Fabrication of (H2PO4−, Ni2+) – α-Fe2O3/Bi2S3 heterojunction photocatalysts with improved visible-light catalytic activity

In this work, the (H2PO4−, Ni2+) – α-Fe2O3(PNF) with abundant oxygen vacancies (OVs) was synthesized, and PNF/Bi2S3 heterojunction photocatalysts were then prepared by hydrothermal process. The obtained PNF showed higher photo-Fenton degradation activity. In comparison with PNF and Bi2S3, the prepared PNF/Bi2S3 composites significantly improved the photocatalytic degradation of p-nitrophenol (p-NP) under visible-light illumination. The production of active species was accelerated in the composite system through the synergistic effect of OVs, heterojunction, and photo-Fenton, resulting in high p-NP degradation efficiency. The PNF/B-2 composite exhibited the highest photocatalytic-Fenton degradation activity, which could be used as a high-performance visible-light-driven photocatalyst for the degradation of difficult-to-degrade pollutants.

β-cyclodextrinbased magnetic ternary nanocomposite for efficient adsorption and photocatalytic degradation of Rhodamine Blue, Gunner 500, Cefixime, and p-Nitrophenol

In this work, ternary metal oxide composite CuO/Fe2O3/ZnO was synthesized through sol-gel method and further modified with β-cyclodextrin (β-CD) to form a novel and effective β-CD-CuO/Fe2O3/ZnO catalyst for the organic pollutants adsorption and degradation. Both catalysts were characterized by P-XRD, SEM, EDX, DRS, PL, DTA/TGA and FT-IR. The adsorption and photocatalytic activity of the above synthesized catalyst were carried out at neutral pH and 1 g/L catalysts dosage for the different types of water pollutants. β-CD-CuO/Fe2O3/ZnO achieved degradation efficiency as 89.3% in 160 min (RhB), 93.2% in 160 min (Gunner 500), 84.1% in 200 min (Cefixime), and 81.5% in 180 min (p-NP). It was also observed that presence of β-CD enhanced the adsorption/degradation efficiency. Kinetics results followed to the pseudo first order (PSO) with the k1 values as 10.40 × 10−3min−1, 0.17 × 10−3min−1, 4.94 × 10−3min−1 and 1.83 × 10−3min−1 for RhB, Gunner 500, Cefixime and p-NP respectively. These photocatalysts exhibit high efficiency in a short reaction time, and good reusability for real wastewater application.

Ultrasonic synthesis of Graphite/C, N co-doped TiO2 nanocomposite as an efficient and durable photocatalyst for the degradation and mineralization of p-nitrophenol

P-nitrophenol (PNP) as an industrial waste effluent is present in many industries, including the dye and textile industries and tanneries, and is the cause of severe human and environmental health risks. In the present study, a facile, effective, and innovative sonochemical procedure was developed at low frequency (20 kHz) and room temperature for the synthesis of graphite (G)/C, N co-doped TiO2 nanocomposite. Herein, tetra n-butyl orthotitanate as the titanium precursor, graphite as the C, and NH4Cl as the N sources were applied in the synthesis of the nano-photocatalyst. The effect of the molar ratio of N/TiO2 was studied in the synthesis of G/C, N co-doped TiO2 nanocomposite. Various techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), High-resolution microscopy (HRTEM), X-ray Photoelectron Spectroscopy (XPS), photoluminescence (PL), Brunauer–Emmett–Teller (BET), Elemental and Mapping analyses (EDS) and UV/Vis diffuse reflectance (UV/vis DRS) were used to characterize the nanocomposite. The results also showed that ultrasound decreased the particle size and improved the size distribution. DRS results showed a narrower band-gap and a red shift of light absorption edge for G/C, N co-doped TiO2 nanocomposite compared to TiO2. The data obtained from XPS established the presence of C, N, Ti, and O elements in the nanocomposite. In addition, the efficiency of the photo-catalytic performance of the nanocomposite was assessed using the pollutant PNP. The fabricated nanocomposite presented photo-catalytic activity much more than TiO2 in PNP degradation with an efficiency of 100 % within 70 min under the illumination of 400 W Xe light. The extraordinary activity of nanocomposite concerning TiO2 was mostly attributed to its high crystallinity, strong visible light absorption, and the impressive separation of photo-induced charge carriers. The radicals in the charge of destruction process were checked via the scavenging tests. The results confirmed that °O2− radical had a basic role in the process of photo-catalytic and an acceptable mechanism was proposed for the photo-catalytic degradation.

Enhancing the Fenton-like degradation of organic contaminants with silicate-iron in aquifer media by ascorbic acid

In this study, silicate-iron (FeSi-ox, FeAlSi-ox) in aquifer media was utilized as an original iron source in groundwater to systematically investigate the effects of ascorbic acid on the degradation of p-nitrophenol (PNP) in the in-situ Fenton-like reaction. Silicate-iron in the aquifer media increased the PNP removal rate by activing H2O2 following the addition of ascorbic acid. The optimal removal rate of PNP was nearly 89% within 40 h, which was 6.8 times higher than that without ascorbic acid. In addition to PNP, some other common pollutants, such as nitrobenzene, trichloromethane, and trichloroethylene, can also be effectively degraded and mineralized. The suitable pH range for the silicate-iron Fenton-like system with ascorbic acid was 5–9, indicating that it is feasible in near-neutral or alkaline groundwater environments. The main functional free radicals were hydroxyl free radicals (•OH), which were produced slowly but continuously. In this novel Fenton-like system, dissolved Fe played a major role in H2O2 decomposition and pollutant degradation. The main mechanism underlying the increased strength of the degradation was the ability of ascorbic acid to facilitate the dissolution of surface Fe from aquifer media and accelerate the cycling of Fe(Ⅲ)/Fe(Ⅱ) in the liquid phase.

Enhanced Stability and Catalytic Activity of a Nanocatalyst with Reusable Ionic Liquid Hydrogels for the Reduction of Organic Pollutants.

Nitroaromatic compounds have a wide range of applications. However, they pose a significant threat to both the environment and human health. Ionic liquid hydrogels (ILs-gels) have emerged as a cost-effective and environmentally friendly option for various applications. However, conventional ILs-gels are known to possess mechanical flaws or defects. The procedure utilized a facile synthesis route that involved the polymerization of acrylamide (AM) and ionic liquids (ILs) to create a novel candidate for nanoparticle absorption. This study resolved this issue by creating toughened hydrophobic combined hydrogels synthesized through the addition of SiO2@poly(butyl acrylate) core-shell inorganic-organic hybrid latex particles (SiO2@PBA) to the AM-ILs mixture. The SiO2@PBA particles were chosen to provide the hydrogels with exceptional stretchability (up to 4050% strain) and high mechanical properties (tensile strength of 126 kPa) by acting as both a nanotoughener and a cross-linking point for hydrophobic linkage. Additionally, the P(AM/ILs)-SiO2@PBA hydrogel served as a template for the in situ and stable formation of palladium (Pd) nanoparticles. By incorporation of these Pd nanoparticles as catalysts into P(AM/ILs)-SiO2@PBA hydrogel carriers, the resulting P(AM/ILs)-SiO2@PBA/Pd hydrogels exhibited the ability to catalyze the degradation of p-nitrophenol. Remarkably, even after 15 applications, the efficiency of the degradation process remained consistently above 90%. Thus, the innovative SiO2@PBA toughened ILs-hydrogel design strategy can be utilized to develop robust and stretchable hydrogel materials for catalytic use in the sewage disposal industry.

Visible Light Motivated the Photocatalytic Degradation of P-Nitrophenol by Ca2+-Doped AgInS2.

4-Nitrophenol (4-NP) is considered a priority organic pollutant with high toxicity. Many authors have been committed to developing efficient, green, and environmentally friendly technological processes to treat wastewater containing 4-NP. Here, we investigated how the addition of Ca2+ affects the catalytic degradation of 4-NP with AgInS2 when exposed to light. We synthesized AgInS2 (AIS) and Ca2+-doped AgInS2 (Ca-AIS) with varying amounts of Ca2+ using a low-temperature liquid phase method. The SEM, XRD, XPS, HRTEM, BET, PL, and UV-Vis DRS characteristics were employed to analyze the structure, morphology, and optical properties of the materials. The effects of different amounts of Ca2+ on the photocatalytic degradation of 4-NP were investigated. Under visible light illumination for a duration of 120 min, a degradation rate of 63.2% for 4-Nitrophenol (4-NP) was achieved. The results showed that doping with an appropriate amount of Ca2+ could improve the visible light catalytic activity of AIS. This work provides an idea for finding suitable cheap alkaline earth metal doping agents to replace precious metals for the improvement of photocatalytic activities.

R-GO coated magnetic high entropy alloy/oxide nanocomposites as highly efficient Fenton and photo-Fenton catalysts

To utilize the synergistic effect of high entropy alloy, high entropy oxide and r-GO (reduced graphene oxide), we prepared r-GO coated nanocomposites comprising bcc high entropy alloy/spinel high entropy oxide (H730) and bcc high entropy alloy/hexagonal high entropy oxide (H725), encompassing elemental constituents such as Aluminum (Al), Chromium (Cr), Manganese (Mn), Iron (Fe), and Cobalt (Co). The samples were meticulously synthesized using the sol-gel technique followed by subsequent calcination at a temperature of 700 °C under nitrogen or air atmospheres. The assessment through X-ray diffraction and electron diffraction methodologies conclusively confirmed the successful formation of nanocomposite structures. The electron microscopy and Raman spectroscopy confirmed the r-GO coating over both the composites. The saturation magnetization values of 32 and 10 emu/g were noticed at 30 kOe for H730 and H725 samples, respectively. In-depth analysis using X-ray photoelectron spectroscopy revealed the coexistence of diverse oxidation states within the constituent elements of the samples. Notably, the H730 nanocomposite exhibited superior catalytic efficacy in comparison to its H725 counterpart for the degradation of p-nitrophenol (PNP) under both Fenton and photo-Fenton reaction conditions. Impressively, complete degradation of PNP was achieved within a remarkably short span of 18 min. Furthermore, the H730 nanocomposite alongwith stronger magnetic attributes, demonstrated a notable 86 % degradation efficiency even after undergoing five consecutive cycles.

Effect of Interfacial Action on the Generation and Transformation of Reactive Oxygen Species in Tripolyphosphate-Enhanced Heterogeneous Fe3O4/O2 Systems.

It has been reported that tripolyphosphate (TPP) can enhance the oxygenation of natural Fe(II)-containing minerals to produce reactive oxygen species (ROS). However, the molecular structure of the TPP-Fe(II) mineral surface complex and the role of this complex in the generation and transformation of ROS have not been fully characterized. In the present study, a heterogeneous magnetite (Fe3O4)/O2/TPP system was developed for the degradation of p-nitrophenol (PNP). The results showed that the addition of TPP significantly accelerated the removal of PNP in the Fe3O4/O2 system and extended the range of effective pH to neutral. Experiments combined with density functional theory calculations revealed that the activation of O2 mainly occurs on the surface of Fe3O4 induced by a structural Fe(II)-TPP complex, where the generated O2•- (intermediate active species) can be rapidly converted into H2O2, and then the •OH generated by the Fenton reaction is released into the solution. This increases the concentration of •OH produced and the efficiency of •OH produced relative to Fe(II) consumed, compared with the homogeneous system. Furthermore, the binding of TPP to the surface of Fe3O4 led to stretching and even cleavage of the Fe-O bonds. Consequently, more Fe(II)/(III) atoms are exposed to the solvation environment and are available for the binding of active O2 and O2•-. This study demonstrates how common iron minerals and O2 in the natural environment can be combined to yield a green remediation technology.

Influence of crystallographic facet orientations of sol-gel ZnO on the photocatalytic degradation of p-nitrophenol in water

Influence of crystallographic facet orientations of sol-gel ZnO on the photocatalytic degradation of p-nitrophenol in water

Interlayer single-atomic Fe−N4 sites on carbon-rich graphitic carbon nitride for notably enhanced photo-Fenton-like catalytic oxidation processes towards recalcitrant organic micropollutants

Glucose-assisted supramolecule self-assembly of melamine and cyanuric acid in the presence of Fe(NO3)3 combined with thermal polymerization is designed to fabricate C-rich g-C3N4-embedded interlayer single-atomic Fe−N4 sites catalyst (Fe1/C-CN). Fe1/C-CN exhibits outstanding photo-Fenton-like catalytic oxidation activity towards typical recalcitrant organic micropollutants. For example, the pseudo-first-order kinetic constant of Fe1/C-CN photo-Fenton-like system is 7.5 and 21.1 times higher than Fe1/C-CN photocatalysis and Fenton-like systems in degradation of p-nitrophenol, and TOC removal efficiency reaches up to 100% after reaction proceeds for 4 h. Mechanism studies reveal that synergy of maximum Fe atom utilization efficiency and boosted photoexcited charge separation dynamics accelerates regeneration of ≡Fe(II) and efficient H2O2 activation of Fe1/C-CN, leading to plentiful active oxygen species for deep oxidation of organic micropollutants. Fe1/C-CN also shows a robust reusability in long-term remediation of organic micropollutants, attributing to interlayer Fe−N coordination interactions for preventing single Fe atoms from agglomeration and leaching to reaction media.

Synthesis oxygen vacancies enriched CuO hierarchical nanosheets for peroxymonosulfate activation toward P-nitrophenol degradation and mechanism

In this work, hierarchical copper oxide (CuO) nanosheet with rich oxygen vacancies was prepared with a facile biotemplates derivatization method. Results show that the as-prepared optimum CuO-II exhibited excellent catalytic performance for peroxymonosulfate (PMS) activation mainly benefiting from large specific surface area and electron transfer efficiency, abundant Cu+ and oxygen vacancies in catalyst. Almost 100 % of P-nitrophenol (PNP) can be degrade within 10 min by CuO-II activating PMS process. The electron paramagnetic resonance (EPR) spectroscopy, reactive species quenching tests and density functional theory (DFT) calculation results revealed that Cu(III)-mediated electron transfer and sulfate radicals were identified as the dominantly responsible for PNP degradation. Meanwhile, CuO-II/PMS system can degrade PNP in a wide range of pH (pH 3 ∼ 10) and with inorganic anions and natural organic matter presence. In addition, CuO-II catalyst has good stability and reusability and performed well toward PNP degradation in the continuous operation. This work not only obtained a facile preparation strategy for obtaining CuO catalyst with excellent catalytic performance, but also gave a new idea for studying the mechanism of CuO activating PMS.