Degradation Of Nitrobenzene Research Articles

Effect of physical and chemical co-application of biochar and sulfidated nano scale zero valent iron on the NB degradation in soil: Key roles of biochar

Sulfidated nano zero-valent iron (S-nZVI) can efficiently degrade nitrobenzene (NB) in water. However, its practical application in soil remediation is constrained by limited contact with soil-sorbed NB, leading to sparse research. Herein, Biochar (BC), with its notable adsorption capacity, was coupled with S-nZVI to assess the role of physical (S-nZVI + BC) and chemical (S-nZVI@BC) co-application of BC and S-nZVI, respectively, on enhancing NB degradation in soil. Regardless of the physical or chemical co-application, there was a remarkable advantage after addition of BC relative to S-nZVI alone. In physical co-application, the NB degradation rate of S-nZVI + BC increased as the increasing BC concentration from 0 to 3.5 g·L−1, attributed to enhanced NB desorption via the solubilization effect of BC, facilitating interaction with S-nZVI. Beyond this concentration, no significant improvement was observed, possibly due to BC obstructing reactive sites on S-nZVI surface. In chemical co-application, the S-nZVI@BC (S-nZVI/BC mass ratio of 1:1) exhibited a high NB degradation rate constant (1.097 h−1) during reaction. Apart from solubilization effect, BC in S-nZVI@BC endowed S-nZVI with a higher anti-oxidation property, hydrophobicity, electron transfer capacity, and dispersion effect, accounting for the higher reactivity of S-nZVI@BC over S-nZVI + BC. Besides, the water/soil ratio and initial soil pH significantly affected NB degradation rate, with the optimum water/soil ratio and initial soil pH being 3 and 5, respectively. Our finding broadens the applicability of BC and may offer a highly effective way in soil remediation.

Enhanced migration and degradation of nitrobenzene in heterogeneous porous media using pulsed direct current electrical resistance heating with hydraulic circulation

Electrical resistance heating (ERH) is a promising in-situ technology for heterogeneous organic contaminated site remediation, yet may have low efficiency when treating semi-volatile organic contaminant (SVOC) of relatively high boiling point. Herein, we chose nitrobenzene as a representative SVOC, and proposed an ERH system powered by pulsed direct current (PDC) with simple hydraulic circulation for improved remediation efficiency in heterogeneous media. The proposed PDC-ERH with hydraulic circulation showed overall improvement in heating performance and energy efficiency, as well as migration and removal of nitrobenzene. This new system improved the uniformity of PDC heating and achieved a temperature increase of ~15°C compared to that using conventional alternating current (AC) of same voltage. Nitrobenzene migration out of the low permeability zone (LPZ) was intensified by the dual effects of heat-induced diffusion enhancement and electric field-induced electroosmotic flow, while subsequent removal was enhanced by electrochemical degradation and volatilization. After 96h, the proposed system has a higher nitrobenzene removal from LPZ (> 97.1%) compared to that using AC (84.0%–95.9%). These results suggest PDC heating coupled with hydraulic circulation was a promising approach for heterogeneous site remediation.

Performance evaluation of Bi/Zn‐impregnated commercial TiO2 nanoparticles for photocatalytic nitrobenzene decomposition

AbstractBACKGROUNDCommercial TiO2 nanoparticles were subjected to modification through Bi and Zn metal doping. The resulting catalysts were comprehensively characterized, and their performance was then reviewed for removal of model pollutant nitrobenzene in water.RESULTSAmidst the synthesized catalysts, the co‐doping of Bi/Zn (0.25:0.75 wt%) demonstrated the best photocatalytic degradation activity, achieving 95% degradation within 90 min of reaction time, with 2.99 × 10−2 min−1 rate constant value. The involvement of different radicals during the degradation process was elucidated by employing appropriate radical scavengers. Furthermore, the degradation results were investigated applying the first‐order kinetic model, leading to the determination of reaction rate constants and initial rates of the degradation process.CONCLUSIONAn improved photocatalytic activity was observed with metal doping due to the synergistic effect of doped metals with commercial TiO2 and profound charge transfer among them. It was observed that performance was increased with temperature rise in the practical range of application, that is, 5–20 °C. This behavior was due to high rate of movement of charge carriers. Further, involvement and functioning of various radical species such as h+, OH− and O2− in nitrobenzene degradation were successfully established using appropriate radical scavengers. © 2024 Society of Chemical Industry (SCI).

Development of morphologically tunable cobalt-zeolitic framework with copper nanowires: A bifunctional catalyst for the analysis of nitrobenzene and ortho-nitrobenzaldehyde in environmental effluents

Hazardous nitroaromatic compounds are a top-priority environmental pollutant and extremely harmful to human health and ecological systems. Hence, selective and ultra-sensitive quantitative analysis of nitroaromatic target detection is highly important nowadays. In this report, we designed and successfully developed the morphologically tunable hybrid composite nature of the cobalt-zeolitic framework (CZ) with copper nanowires (CNW). The morphological structure was highly controlled by switching different weight ratios of CNW into the CZ. Morphological and spectral analysis revealed the developed system is composite with mesoporous properties. Followed by, the designed catalyst was applied to catalytic reduction and electrochemical simultaneous with sensitive sensing of nitrobenzene (NB) and ortho-nitrobenzaldehyde (ONBA). The optimized modified electrode surface exhibited first-rate catalytic activity, the ultra-sensitive limit of detection of 5.3 nM and 2.6 nM (S/N = 3) with a linear response range of 20 nM – 1 mM and 10 nM – 1.5 mM for ONBA and NB. The selectivity of the system is evaluated in the presence of twelve potentially interfering analytes (including phenols, metal ions, and biomolecules). As an added benefit, the CNWCZ/GCE was used to quantify the detection targets in real industrial water samples, with high-rate recoveries of 96.60–99.68±0.05%, and the electrochemical result was validated by standard analytical method. Furthermore, the catalytic degradation of NB and ONBA was tested and achieved more than 91.63±1.13% degradation within 10 and 15 minutes for NB and ONBA, and facile kinetic rate reactions. The developed research findings suggest that catalysts can be used to dual-analyze NB and its derivatives.

Improvement in humus synthesis by the humus precursors derived from nitrobenzene degradation during co-composting of nitrobenzene-polluted soil and cow manure

Nitrobenzene (NB) mineralization problem exists during co-composting of NB-polluted soil and cow manure (CM). Regulating the conversion of NB degradation into humus (HS) synthesis offers a new way to circumvent the aforementioned problem. To explore the influence of the presence of NB on humification process during co-composting, co-composting of NB-polluted soil and cow manure was conducted with composting of clean soil and CM, serving as the control. Results showed that a 54.66% of NB-degradation rate was achieved after 47 d of composting. Simultaneously, compared to CK, not only HS content increased by 18.75%, but also the proportion of fluorescent component with the highest complexity of humic and fulvic acid increased by 21.92% and 44.44%, respectively. NB intermediate metabolites substantially contributed to HS formation. Meanwhile, a markedly strong interaction between bacteria and environmental factors may be crucial for enhancing the humification process in the NB group. It was verified that the addition of NB increased the content of polyphenols (λ = 0.912, p＜0.001) and further improved the synthesis of humic acid (λ = 0.420, p＜0.05) by strengthening the Maillard reaction. Simultaneously, the inhibitory effects of NB and polyphenols on bacterial growth prevented excessive depletion of ammonia nitrogen, favoring humic acid synthesis. These results illustrated that NB intermediate metabolites promoted HS synthesis, which was the prerequisite for subsequent establishment of targeted regulation technology of NB degradation-HS synthesis during co-composting.

Enhanced ozonation of nitrobenzene in water using natural iron ores: Efficiencies, mechanisms and stability

Natural minerals show potential for catalytic ozonation in industrial wastewater treatment. In this study, the efficiencies and mechanisms of two natural iron ores in catalytic ozonation processes (COPs) for aqueous nitrobenzene degradation were initially investigated. Compared with single ozonation process, the removal of TOC increased by about 60 % and 35 % in COPs with natural magnetite and pyrite, respectively. Both natural magnetite and pyrite could promote O3 decomposition to form hydroxyl radicals and 1O2. But the inner reaction pathways were different. The natural magnetite facilitated O3 decomposition through the Lewis acids and the electron transfer between Fe(II)/Fe(III) on the catalyst surface, while electron transfer was the only pathway for O3 decomposition by natural pyrite. Continuous flow fixed-bed reactor was adopted to provide better simulation of the practical operation conditions, so that the potential of engineering application could be evaluated. The natural magnetite exhibited excellent catalytic activity and stability during long period continuous operation in fixed-bed reactor. The removal of TOC maintained at 81.9 % under the optimized operating parameters of hydraulic retention time (2.84 h), O3 velocity (0.25 L min−1) and O3 concentration (30 mg L−1). HCO3− and PO43− obviously inhibited the TOC removal efficiencies through radical scavenging and surface –OH occupying. While low concentration of Cl− and SO42− showed negligible effect on the mineralization of aqueous nitrobenzene. After the continuous operation for 672 h, the removal of TOC for nitrobenzene solution in the magnetite-COP system was still stable at about 80 %. The present study demonstrated the engineering application prospect of the natural iron ores in catalytic ozonation treatment of recalcitrant chemical wastewaters.

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.

High-efficient catalytic ozonation for degradation of nitrobenzene in water with Ce-doped LaCoO3 catalyst

High-efficient catalytic ozonation for degradation of nitrobenzene in water with Ce-doped LaCoO3 catalyst

One-step synthesis of Pt-Nd co-doped Ti/SnO2-Sb nanosphere electrodes used to degrade nitrobenzene.

Ti/SnO2-Sb electrodes possess high catalytic activity and efficiently degrade nitrobenzene (NB); however, their low service life limits their wide application. In this study, we used one-step hydrothermal synthesis to successfully prepare Pt-Nd co-doped Ti/SnO2-Sb nanosphere electrodes. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were applied to characterize the surface morphology, microstructure, and chemical composition of the electrodes, respectively. The electrochemical activity and stability of the electrodes were characterized via linear sweep and cyclic voltammetry, electrochemical impedance spectroscopy, and an accelerated service life test; their performance for NB degradation was also studied. An appropriate amount of Pt-Nd co-doping refined the average grain size of SnO2 and formed a uniform and compact coating on the electrode surface. The oxygen evolution potential, total voltammetric charge, and electron transfer resistance of the Ti/SnO2-Sb-Nd-Pt electrodes were 1.88 V, 3.77 mC/cm2, and 11.50 Ω, respectively. Hydroxy radical was the main active radical species during the electrolytic degradation of nitrobenzene with Ti/SnO2-Sb-Nd-Pt. After Pt-Nd co-doping, the accelerated service life of the electrodes was extended from 8.0 min to 78.2 h (500 mA/cm2); although the NB degradation rate decreased from 94.1 to 80.6%, the total amount of theoretical catalytic degradation of NB in the effective working time increased from 17.4 to 8754.1 mg/cm2. These findings reveal good application potential for the electrodes and provide a reference for developing efficient and stable electrode materials.

Dynamic response of immobilized microbial denitrification reactor under long-term nitrobenzene stress

Denitrification is an effective method for the synergistic degradation of nitrate and nitrobenzene. In this study, microorganisms were cultured by gradually increasing the influent nitrobenzene concentration over 115 days, achieving efficient synergistic transformation of 50 mg/L nitrobenzene and 100 mg/L nitrate with removal efficiencies of 93.65 % and 98.50 %, respectively. It was studied that electrons flowing towards nitrate accounted for over 93.72 %, with that towards nitrobenzene for less than 6.28 %. Nitrobenzene promoted the enrichment growth of biofilm, significantly increased 64.1 % of the content of polysaccharides and 32.7 % of proteins on extracellular polymeric substance. Shannon index showed that nitrobenzene increased richness of bacteria and fungi by 47.6 % and 73.4 % and the dominant phyla were Proteobacteria and Ascomycota respectively. Metagenomic analysis uncovered a noteworthy surge in gene expression associated with carbon metabolism and nitrobenzene reduction, while the expression of denitrification genes exhibited no substantial alterations, elucidating the consistent denitrification efficiency and formidable nitrobenzene elimination capability of the system.

Role of Ag and g-C3N4 over CaTiO3 for effective photocatalytic degradation of nitrobenzene

In the present study, g-C3N4/CaTiO3 (GCT) heterostructure with various Ag contents have been synthesized via simple hydrothermal method and characterized using various instrumental techniques. Stability of synthesized samples was measured by thermogravimetric analysis (TGA) and zeta potential measurement. The photocatalytic activity of all the synthesized was evaluated by the degradation of nitrobenzene (NB) in aqueous media. The photocatalytic activity of heterostructure AGCT was observed enhanced under the light irradiation. This would be attributed to the suitable band structure, resulting in the efficient charge separation and transfer of photogenerated charge carriers. The final percentage of degradation was observed 70% with AGCT5 and 64% with AGCT1 which were highest among other catalysts applied after 2 h. The Ag doping in CT catalyst led to antagonist performance, and to better degradation of NB. The multivalency of Ag leads to prevent agglomeration and recombination of electrons and holes and transferring them from Ag to Ca. The reaction rate (2.36 × 10−3 molL−1 min−1 at 20 °C) and percentage degradation (∼70%) were observed to get increased with the increase in the temperature with the apparent activation energy of 40.3 kJ/mol. The enhanced performance at increased temperature was attributed to overcome the energy of activation and high mobility of charge carriers.

Bio-Coated Graphitic Carbon Nitrides for Enhanced Nitrobenzene Degradation: Roles of Extracellular Electron Transfer

Graphitic carbon nitrides (g-C3N4) and microorganisms could collaboratively enhance photocatalytic properties or facilitate environmental depollution through coupled photocatalytic and biological reactions, which prevented the destruction of photocatalytic stresses to ecological systems and resulted in a sustainable technology for water remediation in rivers and lakes. However, the roles of bio-substances as well as electronic interactions between inorganic and organic systems were still unclear. Herein, g-C3N4, nitrogen-deficient g-C3N4 (ND-g-C3N4), and fluorinated g-C3N4 (F-g-C3N4) were coated with representative bacteria, i.e., Escherichia coli MG 1655, and characterized using integrated spectroscopic techniques. Photocatalytic activities were then evaluated through nitrobenzene degradation performance in an aqueous solution under visible light illumination. Nano-photocatalysts were observed to be adsorbed onto bio-aggregates, and surface hydrophilicity was convinced to be determined in the toxicity of photocatalysts in dark environments. Layered structures of ND-g-C3N4 and F-g-C3N4 were revealed in XRD spectra, and surface coverage of the Luria–Bertani medium was eliminated during E. coli cultivation. Hetero-junctions between photocatalysts and bio-substances were indicated in XPS results. Red-shifts for g-C3N4 and F-g-C3N4 materials as well as a slight blue-shift for ND-g-C3N4 were demonstrated in UV-vis spectra, which might be attributed to the destruction of nitrogen defects on ND-g-C3N4. Owing to the attached bio-substances, nitrobenzene removal could reach twice that with pristine photocatalysts, and ROS quantitative analysis confirmed that hydroxyl radicals were the determined reactive species degrading nitrobenzene in the water solution. The observation of more OH species generation indicated that extracellular electron transfer of E. coli reduced electron–hole recombination and provided reduction sites during photocatalytic degradation of nitrobenzene. This work proved additional electron-transfer paths and reaction mechanisms in hybridized photocatalytic and biological processes, which indicated that bio-activities could be a great promoter of material modification and the incorporation between inorganic and organic systems successfully showed an eco-friendly and sustainable pathway to utilize photocatalysts in natural water.

Phenomenal Insight into Electrochemically Induced Photocatalytic Degradation of Nitrobenzene on Variant Au-Modified TiO2 Nanotubes

TiO2 nanotubes are a prominent type of TiO2-based nanostructure compared to nanorod arrays. A promising way to improve photocatalytic performance is modifying TiO2 nanotubes with metals, either on the surface or inside the tubes. There is a substantial demand for enhancing the conductivity and charge separation of TiO2 nanotubes, with a major focus on gold (Au) modification. Gold (Au) coatings have significantly improved the photocatalytic activity of TiO2 nanotubes, particularly in pollutant oxidation. However, the mechanism underlying the action of Au-modified TiO2 nanotubes in photocatalytic nitrobenzene oxidation under electrochemical induction remains unclear. Therefore, we conducted related experiments to explore the optimal Au concentration under various conditions. Under electric field induction, the maximum removal rate achieved was 54.9%. Lastly, we analyzed the relevant photocatalytic mechanism to elucidate the responses of electrons and holes to a simulated contaminant under a photo-electrochemical field.

Sonocatalytic degradation of nitrobenzene with metal oxide clay nanocomposites

AbstractBACKGROUNDThe presence of a wide range of persistent toxic organic pollutants in industrial effluents poses a serious threat to human and environmental health, emphasising the necessity for developing cost‐effective methods for treating toxic effluents. This study focuses on the synthesis, characterization and evaluation of metal oxide [iron (Fe), copper (Cu) and zinc (Zn)]‐doped clay composite for the sonocatalytic degradation of nitrobenzene (NB) in the presence of ultrasound.RESULTS AND CONCLUSIONSAmong the metal oxides studied, Cu and Fe oxide‐modified clay performed better in the degradation of NB (~99% in the presence of air) compared to a ZnO/clay composite. Process optimization studies were carried with CuO/clay composite at different pHs (2.5–11.5), feed concentrations (50–200 mg L−1) and catalyst loadings (0.25–1.0 g L−1). Neutral pH conditions and higher catalyst loadings of 1 g L−1 were found to be optimal for the efficient degradation of 50 ppm NB. Among the scavengers tested, ethylenediamine tetra acetic acid exhibited strong scavenging effects, resulting in reduced NB degradation compared to isopropyl alcohol and tin tetrachloride, regardless of the scavenger concentration (0.5 and 40 mmol L−1). The catalyst was found to be sufficiently stable for up to four cycles under identical conditions. Additionally, these materials were found to be effective in the degradation of other pollutants [Terephthalic acid, Rhodamine‐B, Ciprofloxacin]. These findings contribute to the development of cost‐effective strategies for the treatment of industrial effluents, reducing the risks posed to both the environment and human health. © 2023 Society of Chemical Industry (SCI).

Degradation of Nitrobenzene by Mackinawite through a Sequential Two-Step Reduction and Oxidation Process.

Mackinawite (FeS) has gained increasing interest due to its potential application in contaminant removal by either reduction or oxidation processes. This study further demonstrated the efficiency of FeS in degrading nitrobenzene (ArNO2) via a sequential two-step reduction and oxidation process under neutral conditions. In the reduction stage, FeS rapidly reduced ArNO2 to aniline (ArNH2), with nitrosobenzene (ArNO) and phenylhydroxylamine (ArNHOH) serving as the intermediates. X-ray photoelectron spectroscopy (XPS) analysis indicated that both Fe(II) and S(II) in FeS contributed electrons to the reduction of ArNO2. In the subsequent oxidation stage with oxygen, by addition of 0.5 mM tripolyphosphate (TPP), ArNH2 generated in the reduction process could be effectively oxidized to aminophenols by hydroxyl radicals (•OH), which would undergo eventual mineralization via ring-cleavage reactions. TPP exerted a favorable role in enhancing •OH production for ArNH2 degradation by promoting the formation of the dissolved Fe(II)-TPP complex, thus enhancing the homogeneous Fenton reaction. Additionally, TPP adsorption inhibited the surface oxidation reactivity of FeS due to the change of Fe(II) coordination. Finally, the effective degradation of ArNO2 by FeS in actual groundwater was demonstrated by using this sequential reduction and oxidation approach. These research findings provide a theoretical basis for a new FeS-based remediation approach, offering an alternative way for comprehensive removal of ArNO2.

Auto-combustion designed BiFeO3/Bi2O3 photocatalyst for improved photodegradation of nitrobenzene under visible light and sunlight irradiation

Herein, using the auto-combustion method, a BiFeO3/Bi2O3 composite was successfully synthesized for the photocatalytic degradation of nitrobenzene under visible illumination. The compound was subsequently characterized using varied characterization approaches, including XRD, SEM/EDS, FTIR, XPS, and UV–VIS techniques. The photocatalytic capability of the resulting sample was assessed by removing nitrobenzene (NB) under solar and artificial (15 W LED lamp) exposure. Within 180 and 240 min of exposure, the prepared BiFeO3/Bi2O3 composite exhibited impressive photocatalytic ability with quasi-total elimination (100%) of NB under both solar and LED lights, in contrast to pure oxides. The photocatalytic capability of BiFeO3/Bi2O3 was 2.88 and 1.67 folds higher than those of BiFeO3 and Bi2O3. This was linked to the effective charge splitting occurring at the BiFeO3/Bi2O3 interface and the lower recombination ratio of charge carriers. Additionally, BiFeO3/Bi2O3 exhibited outstanding sustainability without loss of activity during the first 5 cycles. Aside from this, quenching investigation showed that •OH was responsible for the degradation process. Furthermore, total organic carbon (TOC) analysis confirmed NB mineralization. Based on these previous findings, an appropriate mechanism for NB decomposition was established. Overall, the BiFeO3/Bi2O3 photocatalyst is recommended for use in the efficient photocatalytic removal of organic contaminants owing to its straightforward manufacturing approach, high levels of degradation, and strong structure for potential uses.

Influencing factors and controlled release kinetics of H2O2 from PVP-coated calcium peroxide NPs for groundwater remediation

Calcium peroxide nanoparticles (nCP) as a versatile and safe solid source of hydrogen peroxide (H2O2) receive substantial attention from researchers as a potential groundwater remediation reagent. In this study, we synthesized polyvinylpyrrolidone-coated calcium peroxide nanoparticles (PVP@nCP-PVP) to control the release rate of H2O2 and modulate pH fluctuation simultaneously. The PVP@nCP-PVP is fully characterized and the H2O2 releasing kinetics and mechanisms are investigated. The H2O2 release longevity of nCP increased with the concentration of controlled release material (CRM) encapsulated shell, while the production of H2O2 decreased inversely. The acidic condition is favorable for increasing H2O2 production by promoting the complex decomposition of nCP. The low temperature prolonged the longevity of nCP and suppressed the competitive side reaction for producing O2. The release of H2O2 is consistent with zero-order reaction kinetics and the release of O2 is consistent with first-order reaction kinetics. At last, different nCP composites were employed to construct a Fenton-like system for the degradation of nitrobenzene (NB). The degradation rate was raised from 57.6% by Fe (II)/nCP to 70.0% and 93.7% by Fe (II)/nCP-PVP and Fe (II)/PVP@nCP-PVP systems, respectively. These findings demonstrate that PVP@nCP-PVP has significant advantages in repairing organically contaminated groundwater. Environmental implicationGroundwater contamination poses a great threat to human health and ecosystems. In-situ chemical oxidation (ISCO) is a widely used groundwater remediation technology. Calcium peroxide (CP) as solid hydrogen peroxide showed merits of low cost and high stability, but the further application was limited due to its violent chemical reaction and short longivity in groundwater . In this work, we prepared polyvinylpyrrolidone-coated controlled release nCP (PVP@nCP-PVP) for modulating the release of H2O2. The investigation of H2O2 release kinetics under various environmental conditions enhances the understanding of the inherent relationship between the H2O2 release performance of controlled-release materials and contamination remediation. The feasibility using macromolecules preparing controlled-release oxidizing agents was confirmed, providing a novel solution for groundwater contamination remediation.

Evaluation of the hydrogenation reaction on the electrocatalytic nitrobenzene degradation over (FeCoNiCuZn)xOy high entropy oxides (HEOs)

Environmental pollution is one of the main challenges currently faced by mankind; especially industrial waste-waters treatment and remediation using energy-efficient methodologies. This research focused on the electrochemical degradation of the hazardous nitrobenzene (NB) in aqueous solutions, using novel high-entropy oxide (HEO) electrodes to elucidate the influence of the electrochemical reduction step on the degradation process. The effect of solution pH, dissolved oxygen concentration, anodic applied potential, and cell configurations on NB hydrogenation reaction were evaluated. A synergistic effect between the hydrogenation of nitrobenzene and the degradation was found to drastically enhance the conversion rates. The presence of dissolved oxygen promoted the oxidation reactions, reaching more than 90% nitrobenzene removal at 1.7 V and pH 14. The degradation of the organic by-products was attributed to the formation of the superoxide radical (O2*-) as the main oxidant species. A degradation mechanism was proposed based on the detected intermediates and the decoupling of electrochemical surface reactions observed by EIS at different solution pH.

Fast degradation of atrazine by nZVI-Cu0/PMS: Re-evaluation and quantification of reactive species, generation pathways, and application feasibility.

Additive metal to zero-valent iron (ZVI) could enhance the reduction ability and the additive Cu0 was incorporated to ZVI to accelerate PMS activation with atrazine (ATZ) as target compound. The efficiencies of ATZ degradation and PMS decomposition climbed up firstly and then declined as Cu0 loading increased from 0.01 to 1.00wt% with the maximums at 0.10wt%. SO4•-, HO•, Fe(IV), O2•- and 1O2 were generated by nZVI-Cu0/PMS based on the results of electron paramagnetic resonance (EPR) and simultaneous degradation of nitrobenzene, ATZ, and methyl phenyl sulfoxide (PMSO). The rate constant of Fe(IV) and ATZ was estimated as 7×104 M-1∙s-1 via the variation of methyl phenyl sulfone (PMSO2)formation at different ATZ concentrations. However, Fe(IV) contributed negligibly to ATZ degradation due to the strong scavenging of Fe(IV) by PMS. SO4•- and HO• were the reactive species responsible for ATZ degradation and the yield ratio of SO4•- and HO• was about 8.70 at initial stage. Preliminary thermodynamic calculation on the possible activation ways revealed that the dominant production of SO4•- might originate from the atomic H reduction of PMS in the surface layer of nZVI-Cu0. Ten products of ATZ degradation were identified by HPLC/ESI/QTOF and the possible degradation pathways were analyzed combined with theoretical calculation on ATZ structure. The decrease of temperature or increase of solution pH led to the decline of ATZ degradation, as well as the individual addition of common ions (HCO3-, Cl-, SO42-, NH4+, NO3- and F-) and natural organic matters (NOM). In real water, ATZ was still efficiently degraded with the decontamination efficiency decreasing in the sequence of tap water > surface water > simulated wastewater > groundwater. For the treatment of ATZ-polluted continuous flow, nZVI-Cu0 in double-layer layout had a higher capacity than the single-layer mode. Meanwhile, the leaching TFe and TCu were limited. The results indicate nZVI-Cu0/PMS is applicable and the multiple-layer layout of nZVI-Cu0 is suggested for ATZ-polluted ground water and soil remediation.

Research on the electrochemical treatment of nitrobenzene wastewater: The effects of process parameters and the mechanism of distinct degradation pathways

Nitrobenzene is a typical organic pollutant of petroleum pollutant, which is a synthetic chemical not found naturally in the environment. Nitrobenzene in environment can cause toxic liver disease and respiratory failure in humans. Electrochemical technology provides an effective and efficient method for degrading nitrobenzene. This study, the effects of process parameter (e.g., electrolyte solution type, electrolyte concentration, current density and pH) and distinct reaction pathways for electrochemical treatment of nitrobenzene were investigated. As a result, available chlorine dominates the electrochemical oxidation process compared with hydroxyl radical, thus the electrolyte of NaCl is more suitable for the degradation of nitrobenzene than that of Na2SO4. The concentration and the existence form of available chlorine were mainly controlled by electrolyte concentration, current density and pH, which directly affect the removal of nitrobenzene. Cyclic voltammetry and mass spectrometric analyses suggested that electrochemical degradation of nitrobenzene included two important ways. Firstly, single oxidation: nitrobenzene → other forms of aromatic compounds→ NO−x + organic acids + mineralization products. Secondly, coordination of reduction and oxidation: nitrobenzene → aniline→ N2 + NO−x + organic acid + mineralization products. The results of this study will encourage us to further understand the electrochemical degradation mechanism of nitrobenzene and develop the efficient processes for nitrobenzene treatment.