A study on the photocatalytic degradation of p-Nitroaniline on glass plates by Thermo-Immobilized ZnO nanoparticle

Advances in three-dimensional electrochemical degradation: A comprehensive review on pharmaceutical pollutants removal from aqueous solution

Water pollution, stemming from various contaminants including organic and pharmaceutical pollutants, poses a significant global challenge. Amidst the array of methods available for pollutant mitigation, the three-dimensional electrochemical approach emerges as a standout solution due to its environmental compatibility, cost-effectiveness, and rapid efficiency. This study delves into the efficacy of three-dimensional electrochemical processes in purging organic and pharmaceutical pollutants from aqueous media. Existing research indicates that the three-dimensional electrochemical process, particularly when employing particle electrodes, exhibits notable success in degrading organic and pharmaceutical pollutants. This achievement is largely attributed to the ample specific surface area of particle electrodes and the shortened mass transfer distance, which collectively enhance efficiency in comparison to traditional two-dimensional electrochemical methods. Moreover, this approach is lauded for its environmental friendliness and cost-effectiveness. However, it is imperative to note that the efficacy of the process is subject to various factors including temperature, pH levels, and current intensity. While the addition of oxidants can augment process efficiency, it also carries the risk of generating intermediate compounds that impede the reaction. In conclusion, the three-dimensional electrochemical method proves to be a viable and practical approach, provided that process conditions are meticulously considered and adhered to. Offering advantages from both environmental and economic perspectives, this method presents a promising alternative to conventional water and wastewater treatment techniques.

Facile synthesis of copper nitroprusside chitosan nanocomposite and its catalytic reduction of environmentally hazardous azodyes

One of the biggest issues affecting the entire world currently is water contamination caused by textile industries' incapacity to properly dispose their wastewater. The presence of toxic textile dyes in the aquatic environment has attracted significant research interest due to their high environmental stability and their negative effects on human health and ecosystems. Therefore, it is crucial to convert the hazardous dyes such as methyl orange (MO) azo dye into environmentally safe products. In this context, we describe the use of Copper Nitroprusside Chitosan (Cu/SNP/Cts) nanocomposite as a nanocatalyst for the chemical reduction of azodyes by sodium borohydride (NaBH4). The Cu/SNP/Cts was readily obtained by chemical coprecipitation in a stoichiometric manner. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy were applied to investigate chemical, phase, composition, and molecular interactions. Additionally, Scanning electron microscope (SEM) was used to examine the nanomaterial's microstructure. UV-vis spectroscopy was utilized for studying the Cu Nitroprusside Chitosan's catalytic activity for the reduction of azodye. The Cu/SNP/Cts nanocomposite demonstrated outstanding performance with total reduction time 160 s and pseudo-first order constant of 0.0188 s-1. Additionally, the stability and reusability study demonstrated exceptional reusability up to 5 cycles with minimal activity loss. The developed Cu/SNP/Cts nanocomposite act as efficient nanocatalysts for the reduction of harmful Methyl orange azodye.

ZnO nanostructured matrix as nexus catalysts for the removal of emerging pollutants

Water pollution stands as a pressing global environmental concern, elevating the significance of innovative, dependable, and sustainable solutions. This study represents an extensive review of the use of photocatalytic zinc oxide nanoparticles (ZnO NPs) for the removal of emerging pollutants from water and wastewater. The study examines ZnO NPs' different preparation methods, including physical, chemical, and green synthesis, and emphasizes on advantages, disadvantages, preparation factors, and investigation methods for the structural and morphological properties. ZnO NPs demonstrate remarkable properties as photocatalysts; however, their small dimensions pose an issue, leading to potential post-use environmental losses. A strategy to overcome this challenge is scaling up ZnO NP matrices for enhanced stability and efficiency. The paper introduces novel ZnO NP composites, by incorporating supports like carbon and clay that serve as photocatalysts in the removal of emerging pollutants from water and wastewater. In essence, this research underscores the urgency of finding innovative, efficient, and eco-friendly solutions for the removal of emerging pollutants from wastewater and highlights the high removal efficiencies obtained when using ZnO NPs obtained from green synthesis as a photocatalyst. Future research should be developed on the cost-benefit analysis regarding the preparation methods, treatment processes, and value-added product regeneration efficiency.

Copper and zinc adsorption from bacterial biomass - possibility of low-cost industrial wastewater treatment

The increasing interest of all stakeholders to achieve environmental protection with socioeconomic development puts pressure on industrial processes for less negative impact on the environment. The use of biomass for wastewater treatment has increased due to its low costs and technical feasibility. The present study aimed the use of biomass from a waste of known polluted area for the adsorption of Zn and Cu in a fixed-bed reactor. Samples were collected in Cubatão (Brazil) and cultivated in LB medium. Resulting cultivable bacterial communities were identified as Enterococcus faecalis and Pseudomonas aeruginosa. Adsorption experiments were performed varying the metallic ion concentration and the amount of biomass. Adsorption experiments showed efficiency rates up to 90%. As the concentration of metallic ions increased, the adsorption efficiency decreased, indicating that the active sites were saturated. Activated charcoal demonstrated lower adsorption rates than biomass. Elution process showed that HNO₃ had better efficiency than HCl. Zn adsorption fitted better for Lineweaver-Burk model (Q_max= 200 mg/g of biomass), while Cu adsorption fitted better for Langmuir model (Q_max= 164 mg/g of biomass). Results here demonstrated that the adsorption of Zn and Cu simulating an industrial wastewater by the biomass from a contaminated area is technically feasible.

Preparation and characterization of graphene oxide/O-carboxymethyl chitosan (GO/CMC) composite and its unsymmetrical dimethylhydrazine (UDMH) adsorption performance from wastewater

The removal of unsymmetrical dimethylhydrazine (UDMH) has long been a concern because of its harmful effect on the environment and humans. This study aimed to prepare a novel graphene oxide/O-carboxymethyl chitosan (GO/CMC) composite adsorbent using the solution-blending method for the removal of UDMH from wastewater. The prepared GO/CMC was systematically characterized by Fourier-transform infrared, Raman, scanning electronic microscopy, transmission electron microscopy, thermogravimetric, and zeta potential analyses. The effects of initial pH, temperature, adsorbent dosage, initial concentration, contact time, and recyclability on the UDMH adsorption behaviour of GO/CMC were studied. The adsorption kinetics was consistent with the pseudo-second-order kinetics model, and the adsorption process was mainly controlled by chemisorption. Adsorption isotherms indicated that the adsorption of UDMH by GO/CMC followed the Langmuir adsorption isotherm. The adsorption mechanisms were mainly electrostatic attraction, hydrogen bonding, and surface complexation. Furthermore, GO/CMC composites can be used as a renewable and eco-friendly adsorbent for the removal of UDMH wastewater. The designed GO/CMC composites exhibited a relatively satisfactory recyclability and removal efficiency after five adsorption-desorption cycles.

The catalytic performance of CuFe2O4@CQD nanocomposite as a high-perform heterogeneous nanocatalyst in nitroaniline group reduction

In this study, we fabricated an economical, non-toxic, and convenient magnetic nanocomposite of CuFe₂O₄ nanoparticles (NPs)/carbon quantum dots (CQDs) of citric acid via the co-precipitation method. Afterward, obtained magnetic nanocomposite was used as a nanocatalyst to reduce the ortho-nitroaniline (o-NA) and para-nitroaniline (p-NA) using a reducer agent of sodium borohydride (NaBH₄). To investigate the functional groups, crystallite, structure, morphology, and nanoparticle size of the prepared nanocomposite, FT-IR, XRD, TEM, BET, and SEM were employed. The catalytic performance of the nanocatalyst was experimentally evaluated based on the ultraviolet-visible absorbance to assess the reduction of o-NA and p-NA. The acquired outcomes illustrated that the prepared heterogeneous catalyst significantly enhanced the reduction of o-NA and p-NA substrates. The analysis of the absorption showed a remarkable decrease for ortho-NA and para-NA at λ_max = 415 nm in 27 s and λ_max = 380 nm in 8 s, respectively. The constant rate (k_app) of ortho-NA and para-NA at the stated λ_max was 8.39 × 10^-2 s^-1 and 5.48 × 10^-1 s^-1. The most highlighted result of this work was that the CuFe₂O₄@CQD nanocomposite fabricated from citric acid performed better than absolute CuFe₂O₄ NPs, since nanocomposite containing CQDs had a more significant impact than copper ferrite NPs.

Synthesis of Prussian Blue Analogue and Its Catalytic Activity toward Reduction of Environmentally Toxic Nitroaromatic Pollutants

Nitroanilines are environmentally toxic pollutants which are released into aquatic systems due to uncontrolled industrialization. Therefore, it is crucial to convert these hazardous nitroanilines into a harmless or beneficial counterpart. In this context, we present the chemical reduction of 4-nitroaniline (4-NA) by NaBH4 utilizing Prussian blue analogue (PBA) as nanocatalyst. PBAs can serve as inexpensive, eco-friendly, and easily fabricated nanocatalysts. PBA cobalt tetracyanonickelate hexacyanochromate (CoTCNi/HCCr) was stoichiometrically prepared by a facile chemical coprecipitation. Chemical, phase, composition, and molecular interactions were investigated by XRD, EDX, XPS, and Raman spectroscopy. Additionally, SEM and TEM micrographs were utilized to visualize the microstructure of the nanomaterial. The findings revealed the synthesized PBA of the cubic phase and their particles in nanosheets. The band gap was estimated from the optical absorption within the UV-vis region to be 3.70 and 4.05 eV. The catalytic performance of PBA for the reduction of 4-NA was monitored by UV-vis spectroscopy. The total reduction time of 4-NA by PBA was achieved within 270 s, and the computed rate constant (k) was 0.0103 s-1. The synthesized PBA nanoparticles have the potential to be used as efficient nanocatalysts for the reduction of different hazardous nitroaromatics.

The Catalytic Reduction of Nitroanilines Using Synthesized CuFe2 O4 Nanoparticles in an Aqueous Medium

The primary objective of this research is to investigate the reduction of 4-nitroaniline (4-NA) and 2-nitroaniline (2-NA) using synthesized copper ferrite nanoparticles (NPs) via facile one-step hydrothermal method as a heterogeneous nano-catalyst. Nitroanilines were reduced in the presence and without the catalyst with a constant amount (100 mg) of reducing agent of sodium borohydride (NaBH4 ) at room temperature in water to amino compounds. To characterize the functional groups, size, structure, and morphology of as-prepared magnetic NPs, FTIR, XRD, SEM, and TEM were employed. The UV-Vis spectrum was utilized to explore the catalytic effect of CuFe2 O4 . The outcomes revealed that the synthesized CuFe2 O4 as a heterogeneous magnetic nano-catalyst catalyzed the reduction of 4-NA and 2-NA significantly faster than other candidate catalysts. The outcomes demonstrated that the catalyst catalyzed 4-nitroaniline to para-phenylenediamine (p-PDA) and 2-nitroaniline to ortho-phenylenediamine (o-PDA) with a constant rate of 7.49×10-2  s-1 and 3.19×10-2  s-1 , and conversion percentage of 96.5 and 95.6, in 40 s and 90 s, sequentially. Furthermore, the nanoparticles could be recovered by a magnetic separation method and reused for six consecutive cycles without remarkable loss of catalytic ability.

A Cu(ii) complex supported on Fe3O4@SiO2 as a magnetic heterogeneous catalyst for the reduction of environmental pollutants

Today, the presence of pollutants in the environment has become one of the serious problems and concerns of human beings. To eliminate these pollutants, researchers have made many efforts. One of the most important of these efforts is the reduction of such contaminants in the presence of effective catalysts. Two of the most important and widespread types of these pollutants are nitro compounds and organic dyes. In this paper, we report the synthesis of an efficient and reusable magnetic catalyst using Fe3O4@SiO2 core-shell nanoparticles (NPs), N-(4-bromophenyl)-N'-benzoylthiourea, and copper(ii). Specifically, the Cu(ii)-N-(4-bromophenyl)-N'-benzoylthiourea complex supported on Fe3O4-core magnetic NPs (CM)/SiO2-shell (SS) (CM@SS-BBTU-Cu(ii)) has been prepared. CM@SS-BBTU-Cu(ii) was characterized by FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), TEM (transmission electron microscopy), HRTEM (high resolution transmission electron microscopy), FFT (fast Fourier transform), VSM (vibrating sample magnetometry), TG-DTA (thermogravimetry-differential thermal analysis), STEM (scanning transmission electron microscopy), EDS (energy-dispersive X-ray spectroscopy), and elemental mapping. The synthesized CM@SS-BBTU-Cu(ii) was applied for the reduction of 4-nitrophenol (4-NP), Congo red (CR), and methylene blue (MB) in the presence of NaBH4 (sodium borohydride) at room temperature. CM@SS-BBTU-Cu(ii) can be recycled and reused 5 times. Our results displayed that the performance of the catalyst was not significantly reduced by recycling.

Sustainable and Eco-Friendly Packaging Films Based on Poly (Vinyl Alcohol) and Glass Flakes

The majority of food packaging materials are petroleum-based polymers, which are neither easily recyclable nor ecologically friendly. Packaging films should preferably be transparent, light in weight, and easy to process, as well as mechanically flexible, and they should meet the criteria for food encapsulation. In this study, poly (vinyl alcohol) (PVA)-based films were developed by incorporating glass flakes into the films. The selection of PVA was based on its well-known biodegradability, whereas the selection of glass flakes was based on their natural impermeability to oxygen and moisture. The films were processed using the blade coating method and were characterized in terms of transparency, oxygen transmission rate, mechanical strength, and flexibility. We observed that the incorporation of glass flakes into the PVA matrix did not significantly change the transparency of the PVA films, and they exhibited a total transmittance of around 87% (at 550 nm). When the glass flakes were added to the PVA, a significant reduction in moisture permeation was observed. This reduction was also supported and proven by Bhardwaj’s permeability model. In addition, even after the addition of glass flakes to the PVA, the films remained flexible and showed no degradation in terms of the water vapor transmission rate (WVTR), even after bending cycles of 23,000. The PVA film with glass flakes had decent tensile characteristics, i.e., around >50 MPa. Increasing the concentration of glass flakes also increased the hardness of the films. Finally, a piece of bread was packaged in a well-characterized composite film. We observed that the bread packaged in the PVA film with glass flakes did not show any degradation at all, even after 10 days, whereas the bread piece packaged in a commercial polyethylene bag degraded completely. Based on these results, the developed packaging films are the perfect solution to replace commercial non-biodegradable films.

The Development of iDPC-STEM and Its Application in Electron Beam Sensitive Materials

The main aspects of material research: material synthesis, material structure, and material properties, are interrelated. Acquiring atomic structure information of electron beam sensitive materials by electron microscope, such as porous zeolites, organic-inorganic hybrid perovskites, metal-organic frameworks, is an important and challenging task. The difficulties in characterization of the structures will inevitably limit the optimization of their synthesis methods and further improve their performance. The emergence of integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM), a STEM characterization technique capable of obtaining images with high signal-to-noise ratio under lower doses, has made great breakthroughs in the atomic structure characterization of these materials. This article reviews the developments and applications of iDPC-STEM in electron beam sensitive materials, and provides an outlook on its capabilities and development.

Recent developments in photocatalysis of industrial effluents ։ A review and example of phenolic compounds degradation

Industrial expansion and increased water consumption have created water scarcity concerns. Meanwhile, conventional wastewater purification methods have failed to degrade recalcitrant pollutants efficiently. The present review paper discusses the recent advances and challenges in photocatalytic processes applied for industrial effluents treatment, with respect to phenolic compounds degradation. Key operational parameters including the catalyst loading, light intensity, initial pollutants concentration, pH, and type and concentrations of oxidants are evaluated and discussed. Compared to the other examined controlling parameters, pH has the highest effect on the photo-oxidation of contaminants by means of the photocatalyst ionization degree and surface charge. Furthermore, major phenolic compounds derived from industrial sources are comprehensively presented and the applicability of photocatalytic processes and the barriers in practical applications, including high energy demand, technical challenges, photocatalyst stability, and recyclability have been explored. The importance of energy consumption and operational costs for realistic large-scale processes are also discussed. Finally, research gaps in this area and the suggested direction for improving degradation efficiencies in industrial applications are presented. In the light of these premises, selective degradation processes in real water matrices such as untreated sewage are proposed.

Single and binary adsorption of lead and cadmium ions in aqueous solutions and river water by butylamine functionalized vermiculite: performance and mechanism

Lead and cadmium are toxic to human, animal, and plant health; they enhance oxidative stress indirectly while simultaneously acting through other toxicodynamic mechanisms. In this study, pristine vermiculite (VER) was functionalized with butylamine (BUT) and a novel organoclay (BUT-VER) adsorbent material was produced for simultaneous removal of Pb(II) and Cd(II) in aquatic medium. The adsorbents were characterized by spectroscopic, microscopic, spectrometric, and potentiometric techniques. The adsorption affecting parameters, including pH, time, initial concentration, temperature, and co-existing cations were investigated and optimized. The kinetic data results were in better agreement with pseudo-second-order (PSO) model (R² > 0.992). Multiple isotherm models were used to study the adsorption system and results showed that adsorption was monolayer. The BUT-VER showed an improvement in adsorption capacity in a single system (Pb(II): from 134.2 to 160.6 mg g^-1) and (Cd(II): from 51.1 to 58.9 mg g^-1) while in binary system (Pb(II): from 107.3 to 114.5 mg g^-1) and (Cd(II): from 33.7 to 39.7 mg g^-1), respectively. Furthermore, BUT-VER was tested in real river water and removed efficiency of >99% was achieved in just 1 h. The dominant mechanisms were electrostatic attraction and complexation. BUT-VER was regenerated for five consecutive cycles and showed >90% removal efficiency. These findings suggest that the proposed inexpensive adsorbent has the potential for practical applications of toxic metals removal from water.

Sono-degradation of Reactive Blue 19 in aqueous solution and synthetic textile industry wastewater by nanoscale zero-valent aluminum

Reactive dyes, which are commonly used in the textile industry, are toxic and carcinogenic for the ecosystem and human health. The objective of this study was to investigate the removal of Reactive Blue 19 (RB19) from aqueous solution and synthetic textile industry wastewater using nanoscale zero-valent aluminum (nZVAl), ultrasonic bath (US-40 kHz), and combined US/nZVAl through the consideration of varying experimental parameters such as pH, nZVAl dosage, contact time, and initial RB19 dye concentration. The acidic pH value was an effective parameter to degrade RB19. As the nZVAl dosage and contact time increased, the degradation of RB19 dye from aqueous solution and synthetic textile industry wastewater increased using combined US/nZVAl process. A similar result was obtained for RB19 removal with combined US/nZVAl using 0.10 g dosage at 30 min, whereas it was obtained with nZVAl alone using 0.20 g dosage at 60 min. The sono-degradation process activated the nZVAl surface depending on US cavitation effect and shock waves, and increased RB19 dye uptake capacity with a shorter contact time and lower nZVAl dosage. Increasing the initial dye concentration decreased the removal efficiency for RB19. According to the obtained reusability results, nZVAl particles could be reused for four and two consecutive cycles of combined US/nZVAl and nZVAl alone, respectively.

Catalytic ozonation of chloramphenicol with manganese-copper oxides/maghemite in solution: Empirical kinetics model, degradation pathway, catalytic mechanism, and antibacterial activity

The composite material of manganese-copper oxide/maghemite (Mn_xCu_yO_z/γ-Fe₂O₃) was synthesized by the co-precipitation-calcination method. With the initial concentration of 0.2 g/L Mn_xCu_yO_z/γ-Fe₂O₃ and 10 mg/L O₃, the chloramphenicol (CAP, 10 mg/L) could be completely degraded, which was about 2.22 times of that treated with ozonation alone. The contribution of O₃ and hydroxyl radical (•OH) for CAP degradation in the catalytic process was 6.9% and 93.1%, respectively. According to the effects of catalyst dosage, ozone dosage, and pH on the catalytic performance of Mn_xCu_yO_z/γ-Fe₂O₃, a predictive empirical model was developed for the ozonation with the Mn_xCu_yO_z/γ-Fe₂O₃ system. The HCO₃^-/CO₃^2- and phosphates in solution could inhibit the degradation of CAP with the inhibition ratios 8.45% and 13.8%, respectively. The HCO₃^-/CO₃^2- could compete with CAP and react with •OH, and the phosphates were considered as poisons for catalysts by blocking the surface active sites to inhibit ozone decomposition. The intermediates and possible degradation pathways were detected and proposed. The catalytic ozonation could effectively control the toxicity of the treated solution, but the toxicity was still not negligible. Furthermore, Mn_xCu_yO_z/γ-Fe₂O₃ could be easily and efficiently separated from the reaction system with an external magnet, and it possessed excellent reusability and stability.

Enhanced activation of persulfate by CuCoFe2O4@MC/AC as a novel nanomagnetic heterogeneous catalyst with ultrasonic for metronidazole degradation

In this study, the degradation of Metronidazole (MNZ) using CuCoFe₂O₄@MC/AC catalyst synthesized by microwave-assisted method, as an efficient activator for persulfate (PS) in the presence of ultrasonic (US: 60 kHz) was investigated. X-ray powder diffraction (XRD), Field emission scanning electron microscope (FESEM), Energy dispersive spectroscopy (EDS)-Mapping and Line scan, Fourier transform infrared spectroscopy (FTIR), Vibrating-sample magnetometer (VSM), and Thermal gravimetric analysis (TGA) were conducted to characterize the structure of CuCoFe₂O₄@MC/AC catalyst and then the catalyst dose, PS dose, MNZ concentration, and pH parameters were optimized. The maximum MNZ degradation of 93.78 % was achieved after 15 min reaction at the optimized operation conditions: 0.4 g L^-1 of catalyst, 6 mM of PS, 5 mg L^-1 of MNZ, and pH of 3. The removal efficiency of Total Organic Carbon (TOC) was 87.5 % under optimal conditions. According to kinetic equations, it was found that the MNZ degradation followed both kinetics (pseudo-first-order and Langmuir-Hinshelwood) based on the coefficient of determination (R²) of 0.949, 0.9716, 0.9073, 0.9721, and 0.9662 at concentrations of 5, 10, 15, 20, and 30, respectively. The surface reaction rate constant (K_c) and the adsorption equilibrium constant (K_L-H) of the Langmuir-Hinshelwood model were 0.81 (mg L^-1 min^-1) and 2.184 (L mg^-1), respectively. The free radical scavenging experiments were conducted to illustration the proposed mechanism, which shown that the SO₄^-• was the predominant radicals involved in MNZ degradation. Finally, the regeneration of the catalyst was investigated and showed that after five cycles of use and regeneration by chemical and thermal methods, this catalyst has acceptable chemical stability.

Novel catalytic degradation of Diazinon with ozonation/mg-Al layered double hydroxides: optimization, modeling, and dispersive liquid-liquid microextraction

PURPOSE

In this study MgAl- layered double hydroxides (MgAl-LDH) nanoparticles were prepared by a simple and fast co-precipitation method and used as a catalyst in the ozonation process to degrade diazinon from aqueous solutions.

METHODS

The structure of the synthesized MgAl-LDH was investigated by X-ray diffraction pattern (XRD) and field emission scanning electron microscope-energy dispersive spectroscopy (FESEM-EDX). The response surface methodology (RSM) was used to investigate the effects of different parameters including of reaction time, initial diazinon concentration, pH, and LDH dose on the removal of diazinon by MgAl-LDH catalytic ozonation process. Central Composite Design (CCD) was employed for the optimization and modeling of the process. Dispersive liquid-liquid microextraction (DLLME) method was used to extract diazinon from aqueous samples. The GC-Mass analysis was performed to determine intermediate compounds during diazinon degradation reactions. To evaluate the process performance, TOC and COD removal were measured under optimum conditions.

RESULTS

The highest removal efficiency of 92% was observed in optimum conditions as follow; initial diazinon concentration: 120 mg/L, pH: 8.25, LDH dose: 750 mg/L, and reaction time: 70 min. The quadratic model was obtained with a good fit. The removal of COD and TOC were 80% and 74%, respectively.

CONCLUSION

This process can be suggested and used in the treatment of various industrial wastewaters.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40201-021-00687-w.

A comparative study on the performance of photo/sono/peroxone processes for the removal and mineralization of reactive dye red 198 from aquatic environments

Colored wastewater is the most important problem of textile manufacturing factories, because it contains pollutants with complex structure and toxic, carcinogenic, and mutagenic properties which are non-biodegradable and sustainable in the environment. Reactive Red 198 (RR198) is one of the types of azo dyes which are widely used in the textile industries. Therefore, in this study, the rate of degradation and mineralization of RR198 by UV/US/H2O2/O3 hybrid process was investigated. Influencing factors including: initial dye concentration (100, 200, 300, 400, 500 mg/L), contact time (12.5, 30, 47.5, 65, 82.5 min), pH (3, 5, 7, 9, 11), UV (125-W), H2O2 (10, 20, 30, 40, 50 mg/L), US (160 KHz) and O3 (33 mg/(L·min)) on the removal and mineralization efficiency of RR198 were investigated. Optimization and modeling of the process was done by CCD method. Based on the results of ANOVA analysis, most effective parameters on the RR198 removal efficiency were ozone, US, UV, time, initial dye concentration, pH, and H2O2, respectively, with an impact percentage of 96.86 and less than 1% for ozone and the rest parameters, respectively. Highest removal efficiency of RR198 was obtained by UV/US/H2O2/O3 hybrid process. Optimal conditions for dye removal including: initial dye concentration of 200 mg/L, reaction time of 34 min, H2O2 concentration of 27 mg/L and pH of seven were determined in the presence of ozone gas, UV, and US waves. In these conditions, the removal efficiency of RR198 and TOC were estimated to be 100 and 40.5, respectively. UV/US/H2O2/O3 hybrid process as an advanced oxidation process (AOP) with advantages such as high performance and speed, no sludge production and toxic residues in the treated effluent containing hard biodegradable compounds such as RR198 from aqueous solutions, so can be recommended and used.

One-pot synthesis of zinc oxide nanoparticles via chemical precipitation for bromophenol blue adsorption and the antifungal activity against filamentous fungi

In this research, zinc oxide nanoparticles (ZnONPs) were prepared via a facile one-pot chemical precipitation approach and applied in the adsorption of bromophenol blue (BRB) and as antifungal agents against the filamentous fungi and plant pathogens; Alternaria alternata CGJM3078, Alternaria alternata CGJM3006 and Fusarium verticilliodes CGJM3823. The ZnONPs were characterized by the UV-Vis, FTIR, XRD, TGA, BET, SEM, TEM, and EDX techniques, which showed efficient synthesis. The characteristics ZnO UV-Vis absorption band was observed at 375 nm, while the XRD showed an average ZnONPs crystalline size of 47.2 nm. The SEM and TEM images showed an irregular shaped and aggregated porous structure of 65.3 nm average-sized ZnONPs. The TGA showed 22.9% weight loss at 800 °C indicating the high thermal stability of ZnONPs, while BET analysis revealed a surface area, pore volume and pore diameter of 9.259 m2/g, 0.03745 cm3/g and 9.87 nm respectively. The Freundlich, pseudo-second-order, and intra-particle diffusion models showed R2 > 0.9494 and SSE < 0.7412, thus, exhibited the best fit to the isotherm and kinetics models. Thermodynamics revealed feasible, endothermic, random, and spontaneous adsorption of BRB onto the synthesized ZnONPs. The antifungal assay conducted depicts strong antifungal activities against all three tested fungi. Noticeably, ZnONPs (0.002-5 mg/mL) showed maximum activities with the largest zone of inhibition against A. alternata CGJM 3006 from 25.09 to 36.28 mm. This was followed by the strain F. verticilliodes CGJM 3823 (range from 23.77 to 34.77 mm) > A. alternata CGJM3078 (range from 22.73 to 30.63 mm) in comparison to Bleach 5% (positive control). Additionally a model was proposed based on the possible underlying mechanisms for the antifungal effect. This research demonstrated the potent use of ZnONPs for the adsorption of BRB and as effective antifungal agents.

The removal of tetracycline with biogenic CeO2 nanoparticles in combination with US/PMS process from aqueous solutions: kinetics and mechanism

Antibiotics have received great attention because of their abuse and potential hazards to the human health and environment. In the current work, peroxymonosulfate (PMS) was added to a cerium oxide (CeO₂)/ultrasonic (US) system for tetracycline (TC) degradation. CeO₂ nanoparticles (NPs) were synthesized by a simple and cost-effective method using Stevia rebaudiana leaf extract and cerium nitrate as precursors. The as-synthesized CeO₂ NPs were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier-transform infrared spectroscopy analysis. The effects of catalyst dosage, PMS concentration, US power, initial antibiotic concentration, and pH on TC removal were investigated. The results confirmed the formation of CeO₂ NPs with a fluorite structure, spherical shape, and average particle size of 29 nm. The removal efficiency of TC was 92.6% in the optimum oxidation conditions ([TC] = 15 mg/L, [PMS] = 50 mM, [CeO₂] = 0.6 g/L, pH = 6, and US = 70 W) and followed the zero-order kinetics. Experiment scavenger demonstrated both sulfate and hydroxyl radicals (SO₄^•-, ^•OH) were responsible for degrading antibiotics. Biogenic CeO₂ NPs and ultrasound waves-activated PMS is a promising technology for water pollution caused by contaminants such as pharmaceuticals.

Chlorpyrifos remediation in agriculture runoff with homogeneous solar photo-Fenton reaction at near neutral pH: phytotoxicity assessment

This study represents the first application of Fe-citrate-based photo-Fenton chemistry for the degradation of chlorpyrifos (CPF) spiked into agricultural runoff, and its phytotoxicity assessment. The effects of the initial CPF concentration, time and ratio of Fe-citrate/H₂O₂ on CPF removal during the photo-Fenton reaction were investigated and modeled with analysis of variance using R software by the response-surface methodology package. According to the stationary point in original units, the optimal condition for 70.00% CPF removal was as follows: CPF = 2.5 mg L^-1 (0.0), time = 48.0 min (0.585) and Fe-citrate/H₂O₂ = 0.075 (0.539). Beside running the system at near-neutral pH, another strength of this study is related to the treatment of agricultural runoff contaminated with CPF with a raceway pond reactor, which has the advantages of simplicity of the facilities and procedures, as well as the possibility of using sunlight more efficiently in the field of applications. Finally, untreated and treated agriculture runoffs were used as irrigation to determine their phytotoxic effects on seed germination of cress (Lepidium sativum). Solar photo-Fenton treatment greatly reduced phytotoxicity of agriculture runoff and showed the highest germination percentage (70%) compared to both raw agricultural runoff (60%) and untreated CPF-spiked runoff (35%).

CeO2 foam-like nanostructure: biosynthesis and their efficient removal of hazardous dye

In this study, CeO₂ (cerium oxide) nanoparticles were synthesized using Pinus halepensis pollen and were characterized by field emission scanning electron microscopy (FESEM), powder X-ray diffraction (PXRD) and Raman spectroscopy. The results showed that the ensuing CeO₂ nanostructures, ranging in size from 5 to 25 nm, had high porosity. Synthesized CeO₂ showed the effective catalytic activity towards the photocatalytic removal of dyes. In this work, the photocatalytic activity to removal dye (methyl violet 2B), in the absence of UV radiation, using cerium dioxide nanoparticles (CeO₂-NP) was determined. In this research, four main factors such as effect on color, concentration and pH were examined and maximum %R was obtained about was 97% in 75 min in presence of 50 mg of hydrogen peroxide.

Hybrid UV/COP advanced oxidation process using ZnO as a catalyst immobilized on a stone surface for degradation of acid red 18 dye

Azo dyes are the largest group of synthetic organic dyes which containing the linkage C-N[bond, double bond]N-C and used in various industries such as textile industries leather articles, and some foods. Azo dyes are resistant compounds against the biodegradation processes. The purpose of this research was hybrid UV/COP advanced oxidation process using ZnO as a catalyst immobilized on a stone surface for degradation of acid red 18 (AR18) Dye. In the hybrid process using some parameters such as the dye initial concentration, pH, contact time and catalyst concentration, the process efficiency was investigated. In order to the dye removal, the sole ozonation process (SOP), catalytic ozonation process (COP) and photocatalytic process (UV/ZnO) were used. The ZnO nanoparticles were characterized by XRD, SEM and TEM analyses.  The maximum dye removal was achieved 97% at the dye initial concentration 25 mg/L, catalyst concentration 3 g/L, contact time 40 min and pH 5. As a real sample, the Yazdbaf textile factory wastewater was selected. After that, the physicochemical quality was evaluated. As well as, in the optimal conditions, the AR18 dye removal efficiency was achieved 65%. The kinetic results demonstrated that the degradation reaction was fitted by pseudo-first-order kinetic. The UV/COP hybrid process had high efficiency for removal of resistant dyes from the textile wastewater. Advantages of this technique were as follows:•ZnO nanoparticles were synthesized as catalyst by thermal method and were immobilized on the stones.•pH changes had no significant effect on the removal efficiency.•In the kinetic studies, the decomposition reaction followed pseudo-first order kinetic.