4-nitrophenol In Aqueous Solution Research Articles

Copper-based Layered Double Hydroxides as Heterogeneous Catalyst for Efficient Ozonation of 4-nitrophenol in Aqueous Solution: Synthesis, Characterization, and Performance Evaluation

ABSTRACT Co-precipitation was employed to synthesize copper-based layered double hydroxides, which were subsequently utilized as heterogeneous catalysts for the ozonation of 4-nitrophenol in aqueous solutions. Various analytical techniques, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), were utilized to characterize CuAl-CO3 and CuAl500.The catalytic activity of CuAl-CO3 was evaluated under different reaction conditions. Notably, at pH 11 and 25 °C, CuAl-CO3 exhibited high catalytic efficiency in the ozonation of 4NP. Increasing the catalyst dose, initial pH, and temperature led to enhanced 4NP degradation. An optimal pH of 11 and a catalyst dose of 0.3 g. L−1 resulted in the removal of 78.6% of the initial 4NP concentration. Additionally, ozonation proved to be more efficient at temperatures of 10 °C and 55 °C. The kinetics of 4NP ozonation over CuAl-CO3 and CuAl500 followed a pseudo-first-order reaction. Furthermore, the study demonstrated that CuAl-CO3 and CuAl500 exhibited stability and repeatability across multiple reaction cycles, highlighting their potential for continuous catalytic applications. Overall, this research emphasizes the effectiveness of CuAl-CO3 and CuAl500 as reliable heterogeneous catalysts for the ozonation of 4NP. The results contribute valuable insights into the development of advanced oxidation processes for the treatment of wastewater containing organic contaminants.

Synthesis and Characterization of New Catalysts Grains Based on Iron(Oxy)Hydroxides supported on Zirconium for the Degradation of 4-Nitrophenol in Aqueous Solution

This study reports the preparation of catalyst grains based on oxyhydroxides of iron and zirconium via the coprecipitation method and their application in the degradation of 4-nitrophenol. The morphology, microstructure, and surface composition of these catalysts were characterized by scanning electron microscopy, X-ray diffraction, nitrogen physisorption, and Fourier transform infrared spectroscopy. The catalytic activity of the grains was assessed in the degradation of 4-nitrophenol in a heterogeneous system at different operating conditions. Degradation rates up to 93% were obtained after 4 h of contact time where the catalytic activity of tested materials was higher at pH 7 than in acidic and basic conditions. Amorphous iron hydroxide with a ratio of 75% Zr+25%Fe showed the best catalytic properties. These novel materials are an interesting alternative for facing the water pollution caused by organic compounds.

Efficiency of cerium oxide (CeO2) nano-catalyst in degrading the toxic and persistent 4-nitrophenol in aqueous solution

Cerium oxide (CeO2) generally termed as nanoceria is a rare earth metal oxide, that has become an vital key ingredient in many wide range of applications in different fields like gas sensors, ultraviolet absorbents, catalysis, solid oxide fuel cells, glass-polishing materials etc., In this work, Cerium oxide nanoparticles with uniform structure have been prepared by simple Chemical Precipitation method by using Cerium nitrate hexahydrate as the precursor. The synthesized nanoparticles have been characterised by XRD, FT-IR, SEM, EDAX, TEM, XPS etc., The results of the characterization studies revealed the formation of CeO2 nanoparticles. The photocatalytic ability of the synthesized nanoparticles was studied by degrading 4-nitrophenol dye under visible light irradiation.

Synthesis and Application of Silver and Cobalt Nanoparticles Immobilized on Ionic Liquid-Functionalized Halloysite Nanotubes in the Reduction of 4-Nitrophenol in Aqueous Solution

4-nitrophenol (4-NP) is a highly toxic pollutant for aquatic ecosystem and human life. Therefore, the catalytic reduction of 4-NP into useful 4-aminophenol (4-AP) is of interest. In this regard, two heterogeneous nanocatalysts, including Ag@HNTs-ILs and Co@HNTs-ILs were prepared by grafting imidazolium-based ionic liquids (ILs) onto the halloysite nanotubes (HNTs), followed by immobilization of Ag and Co nanoparticles (NPs), and characterized by means of FT-IR, SEM, EDX, TEM and XRD. The catalytic activity of the prepared nanocatalysts was evaluated for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) under environmentally friendly condition. A set of time, temperature, nanocatalyst amount and NaBH4/4-NP molar ratios was screened. The reusability experiments demonstrated that Ag@HNTs-ILs and Co@HNTs-ILs were highly reusable, up to five reduction cycles without considerable changes in the reaction time. As the synthesized hybrid nanocatalysts could be re-collected and reused for various catalytic runs without any significant loss in their catalytic activity, they could be considered very promising nanomaterials from sustainability point of view.

Magnetic recoverable CuFe2O4/cellulose nanocrystal composite as an efficient catalyst for 4-nitrophenol reduction

CuFe2O4/cellulose nanocrystal (CuFe2O4/CNC) composite featured high magnetic activity was prepared by a facile and one-pot solvothermal method. Based on the solvothermal condition, nanometer-sized magnetic CuFe2O4 ferrite particles (CuFe2O4 NPs) were directly synthesized and CNC was coated on the surfaces of CuFe2O4 NPs. The composition, structure, morphology, and magnetic property of prepared CuFe2O4/CNC material were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible spectroscopy (UV-Vis), and vibrating-sample magnetometer (VSM). FESEM and EDX mapping results showed that CuFe2O4 NPs had a uniform size of 88 nm and were immobilized on the CNC. The catalytic activity of CuFe2O4/CNC was tested in the catalytic reduction of 4-nitrophenol in aqueous solution. After immersion treatment by NaBH4, the CuFe2O4/CNC composite exhibited high catalytic efficiency in reducing 4-nitrophenol to 4-aminophenol. The 4-nitrophenol could be fully reduced in less than 5 minutes. The high catalytic activity was attributed to the easy accessibility of the 4-NP ions by CNC and CuFe2O4 active sites. Owing to its environmental sustainability and being recoverable by magnetic force, CuFe2O4/CNC is suggested to be a promising catalyst with potential applications in wastewater treatment.

Geochemical and Physicochemical Characteristics of Clay Materials from Congo with Photocatalytic Activity on 4-Nitrophenol in Aqueous Solutions

This study investigated the geochemical and physicochemical characteristics of natural clay collected in the Democratic Republic of Congo. The optical properties of the sample collected in Golf (GOL) were tested in the removal of 4-nitrophenol in aqueous solution. The geochemical analysis depicted that all the samples are plotted within the shale quadrant. Furthermore, the Chemical Index of Alteration (CIA) indicated that the samples are extremely weathered. The particle size distribution ranged from 0.41 to 418.6 μm, while the pore diameters for all the samples were under 100 Å. A flake-like surface morphology was observed in all the samples. SiO2, Al2O3, Fe2O3, K2O, and TiO2 were the major chemical compounds found in all the samples, while the XRD analysis showed the presence of quartz, kaolinite, magnetite, and illite. The presence of metal oxides (i.e., TiO2 and Fe2O3) indicated that these natural clays can be used for photocatalytic oxidation of pollutants. The sample collected in Katuba (KAT) displayed the higher reflectance percentages for the selected wavelengths except at 200 nm. Interestingly, the GOL sample exhibited lower energy band gaps (2.68 and 3.94 eV) necessary for photocatalysis. The untreated GOL clay sample removed 99.13% of 4-nitrophenol from aqueous solution through the photodegradation process. The usage of the untreated GOL clay could be a cost-effective solution in the removal of 4-nitrophenol in wastewater.

Activity in the Photodegradation of 4-Nitrophenol of a Zn,Al Hydrotalcite-Like Solid and the Derived Alumina-Supported ZnO

A Zn,Al layered double hydroxide (LDH), with the hydrotalcite structure and the mixed oxide obtained upon its calcination at 650 °C, was tested in the adsorption and photocatalytic degradation of 4-Nitrophenol in aqueous solution. The Zn,Al LDH was fast and easily obtained by the coprecipitation method. Hydrothermal treatment under microwave irradiation was applied to compare the effect of the ageing treatment on the photocatalytic behavior. The efficiency of the synthetized solids was compared to that of a commercial ZnO. The ageing treatment did not improve the performance of the original samples in the degradation of 4-nitrophenol. The activity of the synthetized solids tested exceeded that observed for the reaction with commercial ZnO. The photocatalytic performance of the original non-calcined hydrotalcite is similar to that of commercial ZnO. The calcined hydrotalcite showed a better performance in the adsorption-degradation of the contaminant than ZnO, and its reusability would be possible as it recovered the hydrotalcite-like structure during the reaction.

Impact of nanoceria shape on degradation of diethyl paraoxon: Synthesis, catalytic mechanism, and water remediation application

A series of nanomaterials have been demonstrated to be powerful for direct degradation of diethyl paraoxon (EP) to diethyl phosphate and 4-nitrophenol in aqueous solution. However, comparison of catalytic activity of different nanomaterials toward EP is rarely explored. In the present study, four different morphological nanoceria (cubes, rods, polyhedral, and spheres) were synthesized, characterized, and evaluated as a catalyst for the degradation of EP in comparison to other commercially available nanomaterials. Among the tested nanoceria, the cerium dioxide (CeO2) nanopolyhedra possess the best catalytic activity toward the hydrolysis of EP owing to their abundant oxygen vacancy sites, optimal ratio of Ce(III) to Ce(IV), and specific exposed facets. Under the conditions of 0.2 M NH3/NH4Cl buffer and 25 °C, the CeO2 nanopolyhedra catalyzed the reduction of EP to 4-nitrophenol with a >99% conversion at pH 8.0 for 50 h, at pH 10.0 for 12 h, and at pH 12.0 for 2.5 h. The catalytic degradation of nearly 100% EP in NH3/NH4Cl buffer (pH 10.0) at 25 °C is in the decreasing order of CeO2 nanopolyhedra > CeO2 nanorods > ZnO nanospheres (NSs) > CeO2 nanocubes > TiO2 NSs > CeO2 NSs > Fe3O4 NSs ~ Co3O4 NSs ~ control experiment. The mechanism for the degradation of EP was confirmed by monitoring catalytic kinetics of the CeO2 nanopolyhedra in the presence of EP, dimethyl paraoxon, 4-nitrophenyl phosphate, and parathion. The nanocomposites were simply fabricated by electrostatic self-assembly of the CeO2 nanopolyhedra and poly(diallyldimethylammonium chloride)-capped gold nanoparticles (PDDA-AuNPs). The resultant nanocomposites still efficiently catalyzed NaBH4-mediated reduction of 4-nitrophenol to 4-aminophenol with a normalized rate constant of 6.68 ± 0.72 s−1 g−1 and a chemoselectivity of >99%. In confirmation of the robustness and applicability of the as-prepared nanocomposites, they were further used to catalyze the degradation of EP to 4-amionphenol in river water and seawater.

Synthesis of Platinum Nanoparticles with High Catalytic Activity Supported on Magnetic Carbon Nanospheres

In this work, the Pt NPs/Fe3O4-DIB-DETA-CNSs nanohybrids have been synthesized through in situ deposition of uniform Pt and Fe3O4 NPs on the surface of carbon nanospheres. The resulting nanohybrids exhibit good catalytic performance and stability in the reduction of 4-nitrophenol in aqueous solution. Meanwhile, they can be easily separated through an external magnet, and their catalytic properties were also viable even after ten cycles. The unusual catalytic activity should be ascribed to the effects of the Pt NPs anchored on carbon nanospheres.

Coral-like Au/TiO2 Hollow Nanofibers with Through-Holes as a High-Efficient Catalyst through Mass Transfer Enhancement

One-dimensional (1D) hollow nanomaterials were widely used in the catalysis field. However, the inner surfaces of 1D hollow nanostructures could not be effectively utilized in liquid reaction because of diffusional limitation caused by the large ratio of length to diameter. In this work, a template-assisted coaxial electrospinning method was developed to prepare TiO2 hollow nanofibers with through-holes which were further employed as a carrier for Au nanoparticles. The Au/TiO2 hollow nanofibers with through-holes showed significant catalytic activity enhancement to the reduction of 4-nitrophenol in aqueous solution compared with solid and hollow nanofiber counterparts. The through-holes which provided unrestricted macropores for mass transfer in liquid solution were studied to be accounted for the catalytic activity enhancement. The through-hole structures can widen the application ranges and increase the efficiencies of zero-dimensional or 1D hollow nanomaterials.

Determination of the crystallinity of TiO2 photocatalysts

This study reports a new simple method to determine the crystallinity of anatase and rutile TiO2 photocatalysts. The crystallinity degree of various anatase and rutile samples was estimated by XRD analysis from the ratio among the full width at half maximum intensities of the main diffraction peaks of anatase or rutile and the (111) peak of CaF2 as internal standard. The photocatalytic activity of selected powders was tested employing the photodegradation of 4-nitrophenol in aqueous solution as probe reaction. The results showed that the photoactivity of the investigated samples increased with increasing crystallinity and crystallite size.

One-Step Synthesis of Size-Tunable Gold@Sulfur-Doped Graphene Quantum Dot Nanocomposites for Highly Selective and Sensitive Detection of Nanomolar 4-Nitrophenol in Aqueous Solutions with Complex Matrix

In this study, a simple one-step synthesis procedure for the fabrication of a gold nanoparticle (Au NP)@sulfur-doped graphene quantum dot (Au@S-GQD) with tunable size was developed for the sensitive and selective detection of 4-nitrophenol in water and wastewater with a complex matrix. The particle size of two to six layered S-GQD is in the range of 1–7 nm with a mean diameter of 4.0 ± 0.5 nm. The S-GQD serves as a reducing agent for both Au ions and 4-nitrophenol reduction to generate Au@S-GQD nanocomposites as well as to produce the absorption signal of 4-aminophenol at 307 nm. The particle size of Au@S-GQD is tunable by simply adjusting the Au precursor concentration, and the mean diameter increases from 5 to 25 nm when the Au precursor concentration increases from 50 to 200 μM. Moreover, the Au@S-GQD nanocomposite exhibits good UV–visible absorption properties, and the change of wavelength ratio between 307 and the SPR peak of Au at 530 nm (A307/A530) is used to detect nanomolar levels of 4-nitropheno...

Palladium Supported on Titanium Carbide: A Highly Efficient, Durable, and Recyclable Bifunctional Catalyst for the Transformation of 4-Chlorophenol and 4-Nitrophenol.

Developing highly efficient and recyclable catalysts for the transformation of toxic organic contaminates still remains a challenge. Herein, Titanium Carbide (Ti3C2) MXene modified by alkali treatment process was selected as a support (designated as alk-Ti3C2X2, where X represents the surface terminations) for the synthesis of Pd/alk-Ti3C2X2. Results show that the alkali treatment leads to the increase of surface area and surface oxygen-containing groups of Ti3C2X2, thereby facilitating the dispersion and stabilization of Pd species on the surface of alk-Ti3C2X2. The Pd/alk-Ti3C2X2 catalyst shows excellent catalytic activity for the hydrodechlorination of 4-chlorophenol and the hydrogenation of 4-nitrophenol in aqueous solution at 25 °C and hydrogen balloon pressure. High initial reaction rates of 216.6 and 126.3 min−1· are observed for the hydrodechlorination of 4-chlorophenol and hydrogenation of 4-nitrophenol, respectively. Most importantly, Pd/alk-Ti3C2X2 exhibits excellent stability and recyclability in both reactions without any promoters. The superior property of Pd/alk-Ti3C2X2 makes it as a potential material for practical applications.

Lignin-based activated carbons as metal-free catalysts for the oxidative degradation of 4-nitrophenol in aqueous solution

A wheat and hemp lignin, obtained from a soda pulping-precipitation process, was carbonized at 800°C under N2 atmosphere. The resulting carbon material was thermally activated under oxidative atmosphere at four different temperatures (150, 200, 300 and 350°C). The materials prepared at higher activation temperatures (300 and 350°C) have proven their potential in the elimination of 4-nitrophenol (4-NP) from aqueous model solutions (5gL−1) when using catalytic wet peroxide oxidation (CWPO). In these conditions we were able to remove around 70% of 4-NP after 24h, with an efficient H2O2 decomposition, in experiments conducted at relatively mild operating conditions (atmospheric pressure, 50°C, pH=3, catalyst load=2.5gL−1 and [H2O2]0=17.8gL−1). By increasing the working temperature to 80°C, complete 4-NP removal was obtained within 48h (against 93% 4-NP removal at 50°C), with an efficiency of H2O2 consumption of 70% and a significant mineralization (61%). On the other hand, the materials prepared at lower activation temperatures (150 and 200°C), with higher basicity, promote the faster but inefficient H2O2 decomposition, 4-NP removal being lower than 25% after 24h at 50°C in CWPO. This can be attributed to the formation of species other than HO radicals during H2O2 decomposition, the recombination of the formed radicals into non-reactive species and a poor adsorption capacity.

A comparison of the photocatalytic activity between commercial and synthesized mesoporous and nanocrystalline titanium dioxide for 4-nitrophenol degradation: Effect of phase composition, particle size, and addition of carbon nanotubes

The photodegradation of 4-nitrophenol in aqueous solution was studied by using titania-based photocatalysts, in particular standard commercial titania samples (anatase and rutile, Hunstmann; P25 and Aeroxide VP P90, Evonik) and a mesoporous and nanocrystalline titania synthesized under hydrothermal conditions. A comparison between the commercial products and our preparations made evident a different particle size and phase composition. Moreover, in order to investigate a possible synergism between TiO2 and carbon nanotubes (CNTs), further two samples were purposely synthesized by adding to the reaction mixture used for the catalyst preparation a small amount of single-walled or multi-walled carbon nanotubes (SWCNTs and MWCNTs). Among the investigated solids, the nanocrystalline titania resulted to be the most active photocatalysts. The less active solids were rutile and mesoporous titania. The addition of a small amount of MWCNTs further increased the photoactivity of the nanocrystalline titania.

Spectroscopic investigations on the simulated solar light induced photodegradation of 4-nitrophenol by using three novel copper(II) porphyrin–TiO2 photocatalysts

Three porphyrins containing different functional groups (OH, CO2C2H5, COOH), 5-(4-hydroxy) phenyl-10,15,20-triphenyl porphyrin (1a), 5-(4-ethylacetatatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1b), 5-(4-carboxylatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1c), were synthesized and characterized spectroscopically. The CuPp(2a, 2b, 2c)–TiO2 photocatalysts were then prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis-DRS), Fourier-transform infrared spectroscopy (FT-IR). The photocatalytic activities of the photocatalysts were investigated by carrying out the photodegradation of 4-nitrophenol in aqueous solution under simulated solar irradiation. It was found that the CuPp(2a, 2b, 2c)–TiO2 enhanced the photocatalytic efficiency of bare TiO2 in photodegrading the 4-NP due to the interaction between CuPp(2a, 2b, 2c) and TiO2, resulted in the enhancement of the photogenerated electron–hole separation. The reasons of this enhanced photocatalytic activity were also discussed. Based on the present study, it could be considered as a promising photocatalyst for the further industrial application.

Radiolytic degradation of 4-nitrophenol in aqueous solutions: Pulse and steady state radiolysis study

The radiation induced degradation of 4-nitrophenol (4-NP) has been studied by gamma irradiation, while the reactivity and spectral features of the short lived transients formed by reaction with primary transient radicals at different pHs has been investigated by pulse radiolysis technique. In steady state radiolysis a dose of 4.4kGy is able to degrade 98% of 1×10−4moldm−3 4-NP. 4-NP has pKa at 7.1, above which it is present in the anionic form. At pH 5.2, •OH and N3• radicals were found to react with 4-NP with rate constants of 4.1×109dm3mol−1s−1 and 2.8×108dm3mol−1s−1, respectively. Differences in the absorption spectra of species formed in the reactions of 4-NP with •OH and N3• radicals suggested that •OH radicals add to the aromatic ring of 4-NP along with electron transfer reaction, whereas N3• radicals undergo only electron transfer reaction. At pH 9.2, rate constants for the reaction of •OH radicals with 4-NP was found to be higher by a factor of 2 compared to that at pH 5.2. This has been assigned to the deprotonation of 4-NP at pH 9.2.

Facile preparation of a variety of bimetallic dendrites with high catalytic activity by two simultaneous replacement reactions

Herein, two simultaneous replacement reactions were explored to prepare a variety of bimetallic dendrites (AgCu, AgPd, AuPd, CuAu, CuPt and CuPd) in one step, using commercial Mg powder as a sacrificial metal to reduce the bimetallic precursors in aqueous solution. We demonstrate in detail how the morphologies and compositions of the bimetallic dendrites are affected by factors such as the potential difference between the metal redox couples, molar ratios of precursors, ligands, reaction times and total precursor concentrations, taking dendritic AgCu as an example. In addition, monometallic Ag and Cu dendrites were also prepared for comparison. The application of these prepared dendrites as high performance catalysts for the reduction of 4-nitrophenol in aqueous solution at room temperature was further explored. The order of activity CuPd > CuPt > CuAu > Cu > Ag1Cu1 > Ag3Cu1 > AuPd > Ag1Cu3 > AgPd > Ag was established for the prepared dendrites based on normalized kinetic parameters according to our proposed formula.

Design of H3PW12O40/TiO2 and Ag/H3PW12O40/TiO2 film-coated optical fiber photoreactor for the degradation of aqueous rhodamine B and 4-nitrophenol under simulated sunlight irradiation

In order to improve sunlight-energy utilization efficiency of the photocatalyst for the degradation of organic pollutants in wastewater, a novel photoreactor that comprised H3PW12O40/TiO2 or metallic Ag deposited H3PW12O40/TiO2 film-coated optical fiber bundles was designed by the steps of sol–gel, hydrothermal treatment, photoreduction, and dip coating. The H3PW12O40/TiO2 or Ag/H3PW12O40/TiO2 film exhibited anatase phase, mesoporosity, and charge transfer band in the range of 200−400nm or 200−800nm. The photocatalytic activity of the H3PW12O40/TiO2 and Ag/H3PW12O40/TiO2 film-coated optical fibers was evaluated by the degradation of rhodamine B and 4-nitrophenol in aqueous solutions under the irradiation of commercial Xe lamp and self-made solar simulator (320nm<λ<680nm). The enhanced photocatalytic activity of the H3PW12O40/TiO2 or Ag/H3PW12O40/TiO2 film in comparison of TiO2 film was obtained and explained in terms of the synergistic photocatalytic effect between Keggin unit and TiO2 as well as surface plasmon resonance effect of metallic Ag; and considerably high photocatalytic activity of the H3PW12O40/TiO2 and Ag/H3PW12O40/TiO2 film in the optical fiber photoreactor is explained by the superior light-energy utilization of the catalyst in the optical-fiber reactor. Finally, the reusability of the catalyst film was evaluated through six consecutive catalytic runs.

Efficient adsorption-photodegradation of 4-nitrophenol in aqueous solution by using ZnO/HZSM-5 nanocomposites

In this paper, the newly prepared ZnO/HZSM-5 nanocomposites were suggested as the promising alternative materials for conventional means of waste water treatment. The combination effect of adsorption–photodegradation for the removal of 4-nitrophenol (4-NPh), as a biorefractory pollutant, occurred successfully when 7 wt.% of ZnO nanoparticles were incorporated in HZSM-5 zeolite. It was found that both the hydrophobicity and size-selectivity of HZSM-5 toward 4-NPh enhanced the adsorption process. The photodegradation of 4-NPh solutions was performed under UV irradiation and the influence of various parameters such as ZnO loading amount, pH dependence and initial concentration of 4-NPh were investigated. The results indicated that during the fixed reaction time (90 min) about 91% total organic carbon of solution, containing 4-NPh (20 mgl − 1 ) was removed at pH = 5. Batch kinetic studies were conducted to evaluate the adsorption–photodegradation process. The pseudo-second-order fit well over the range of reaction time. It can be suggested that encapsulating ZnO clusters in the zeolites is a proper way to inhibit the agglomeration of ZnO nanoparticles and also to retard the recombination of photogenerated electron–hole in photocatalytic activity.