Degradation Of Benzoic Acid Research Articles

Synthesis of pure and cobalt (Co) doped SnO2 nanoparticles and its structural, optical and photocatalytic properties

Nanocrytalline tin oxide (SnO2) nanoparticle along with cobalt (3 and 5%) was successfully synthesized by chemical precipitation method. The influence of Co doping on structural, optical and photocatalytic properties of SnO2 nanoparticles were investigated by using powder X-ray diffraction, Transmission electron microscope, UV–Vis spectra, photoluminescence and Fourier infrared spectra analysis. The result shows that obtained SnO2 have tetragonal rutile type structure and it has been found that the crystalline size for various concentration of Co (3 and 5%) was 41 and 32 nm respectively. UV–Vis spectra revealed that the band gap energy of pure and Co doped SnO2 were 3.58, 3.32 and 3.12 eV respectively. The photocatalytic degradation of phenol and benzoic acid was systematically investigated by using Co–SnO2 catalyst under UV irradiation. The result showed that Co doped SnO2 possesses highest photocatalytic property as compared to pure SnO2. The photocatalytic mechanism of Co doped SnO2 also is discussed.

Fabrication and enhanced electrocatalytic activity of TiO2 nanotubes based three-dimensionally macroporous SnO2 with mesoporous walls

The TiO2 nanotubes based three-dimensionally macroporous SnO2 with mesoporous walls (TNTs/3D-SnO2) have been fabricated using the dual-templating strategy. The physicochemical properties of the electrodes were characterized by means of techniques such as SEM, HRTEM, XRD, XPS, BET, CV, EIS. The structural features of 3D SnO2 had an important influence on the electrocatalytic performance. With PMMA and F127 as the template, the obtained TNTs/3D-SnO2-2 electrode had the outstanding structure, the smallest lattice parameters for SnO2, and largest surface area when compared to the flat TNTs/SnO2 electrode. The results of electrochemical measurements indicated that the TNTs/3D-SnO2-2 electrode provided the largest electroactive sites and best electron transmission capability. Due to the 3D macroporous skeleton with mesopores and smaller nanoparticles, the TNTs/3D-SnO2-2 electrode exhibited the superior electrocatalytic activity toward degradation of benzoic acid. The mass transfer coefficient km at TNTs/3D-SnO2-2 electrode is 3.79×10−5ms−1, 2.4 times as much as that of flat TNTs/SnO2. The improved OH generation and enhanced mass transport were responsible for the increased electrocatalytic oxidation ability of TNTs/3D-SnO2-2.

Effect of benzoic acid on soil microbial communities associated with soilborne peanut diseases

As potent allelochemicals, phenolic acids are believed to be associated with soilborne diseases, and can influence plant-microbe interactions. Benzoic acid (BA) is one major phenolic acid found in peanut (Arachis hypogaea) root exudates. The objectives of this study were to estimate the BA degradation in the soil and its effects on soil bacterial and fungal communities and to detect the specific taxa responding to BA amendment. BA degradation was investigated by monitoring the BA retained in the soil using high-performance liquid chromatography (HPLC) and the CO2 production rate using gas chromatography (GC). The abundance and diversity of the bacterial and fungal communities were investigated by quantitative real-time PCR (qPCR) and Illumina MiSeq sequencing. The results showed that the BA concentration decreased significantly with an increased rate of CO2 production during the first 36h after amendment, implying that the BA in the soil was quickly metabolized by the microbes. Quantitative PCR analysis further detected a significant increase in soil bacterial and fungal abundances in response to BA addition, but a reduced bacteria-to-fungi ratio. As a result of BA amendment, the relative abundance of Fusarium, Bionectria and Trichoderma was markedly increased, whereas Metarhizium was reduced. Moreover, BA (0.1mmolL−1) promoted the mycelial growth, sporulation capacity and conidial germination of the peanut root rot pathogen Fusarium sp. in vitro. Among bacteria, the relative abundance of Betaproteobacteria was significantly increased in response to BA treatment, whereas the relative abundances of AD3 and Actinobacteria were reduced. A deeper taxonomic analysis of the Betaproteobacteria taxa showed a great increase in the abundance of the genus Burkholderia, from 0.71% to 10.12%, in response to BA amendment. Constructing clone libraries with the partial 16S rRNA genes of Burkholderia further demonstrated that BA amendment had modified the Burkholderia species composition. Our results highlight that the effects of BA in the soil are reflected by changes in populations of soil microbes and suggest that the response of specific microbes such as Fusarium and Burkholderia to BA might be associated with the development of soilborne diseases in monocultures.

Photoelectrocatalytic degradation of benzoic acid using immobilized tungsten trioxide photocatalyst

The thin films of WO3 were deposited with different solution quantities using chemical spray pyrolysis technique. The WO3 film thickness effect on the photoelectrochemical, structural, morphological and optical properties is studied. Polycrystalline, monoclinic WO3 films possess photoelectrochemical performance having onset potentials around +0.3 V/SCE in 0.01 M HClO4. The maximum photocurrent density (Iph = 635 μA/cm2) is observed for the film deposited with 75 ml solution quantity. The FE-SEM image shows compact structure with petals like morphology. The estimated indirect band gap of WO3 films lies in the range of 2.60–2.65 eV. The photoelectrocatalytic degradation of benzoic acid is studied using WO3 photoelectrode under UV light illumination and 57 ± 3% removal of benzoic acid is achieved. The mineralization of benzoic acid in aqueous solution has been studied by measuring COD values.

Activation of hydrogen peroxide during the corrosion of nanoscale zero valent copper in acidic solution

Activation of hydrogen peroxide (H2O2) and its mechanism were investigated during corrosion of nanoscale zero valent copper (nZVC) in acidic aqueous solution. As the radical probe compound, benzoic acid (BA) degradation was completely achieved after 25min in the nZVC/H2O2 system at initial pH 3.0. H2O2 can accelerate the corrosion of nZVC to release Cu+ resulting in the further activation of H2O2via a Fenton-like reaction in acidic aqueous solution. The released Cu+ during the corrosion of nZVC is the main effective copper species to activate H2O2 to produce OH in the nZVC/H2O2 system. Hydroxyl radical (OH) was verified as the primary reactive oxidant which is responsible for BA degradation in the nZVC/H2O2 system owing to the intense inhibition of BA degradation with the addition of excess tert-butyl alcohol (TBA). Moreover, acidic aqueous solution facilitates the degradation of BA and optimum initial pH for BA degradation is 3.0. Higher nZVC dosage could enhance the degradation rate of BA. In addition, the present study put forward an interesting idea to make full use of intermediate Cu+ to activate H2O2 during corrosion of nZVC to degrade organic contaminants.

Radicals induced from peroxomonosulfate by nanoscale zero-valent copper in the acidic solution.

A highly efficient advanced oxidation process for the degradation of benzoic acid (BA) during activation of peroxomonosulfate (PMS) by nanoscale zero-valent copper (nZVC) in acidic solution is reported. BA degradation was almost completely achieved after 10 min in the nZVC/PMS process at initial pH 3.0. PMS could accelerate the corrosion of nZVC in acidic to release Cu+ which can further activate PMS to produce reactive radicals. Both sulfate radical (SO4-•) and hydroxyl radical (•OH) were considered as the primary reactive oxidant in the nZVC/PMS process with the experiments of methyl (MA) and tert-butyl alcohol quenching. Acidic condition (initial pH ≤ 3.0) facilitated BA degradation and pH is a decisive factor to affect the oxidation capacity in the nZVC/PMS process. Moreover, BA degradation in the nZVC/PMS process followed the pseudo-first-order kinetics, and BA degradation efficiency increased with the increase of the nZVC dosage.

Biodegradation of phthalic acid esters by a newly isolated Mycobacterium sp. YC-RL4 and the bioprocess with environmental samples.

Bacterial strain YC-RL4, capable of utilizing phthalic acid esters (PAEs) as the sole carbon source for growth, was isolated from petroleum-contaminated soil. Strain YC-RL4 was identified as Mycobacterium sp. by 16S rRNA gene analysis and Biolog tests. Mycobacterium sp. YC-RL4 could rapidly degrade dibutyl phthalate (DBP), diethyl phthalate (DEP), dimethyl phthalate (DMP), dicyclohexyl phthalate (DCHP), and di-(2-ethylhexyl) phthalate (DEHP) under both individual and mixed conditions, and all the degradation rates were above 85.0% within 5days. The effects of environmental factors which might affect the degrading process were optimized as 30°C and pH 8.0. The DEHP metabolites were detected by HPLC-MS and the degradation pathway was deduced tentatively. DEHP was transformed into phthalic acid (PA) via mono (2-ethylhexyl) phthalate (MEHP) and PA was further utilized for growth via benzoic acid (BA) degradation pathway. Cell surface hydrophobicity (CSH) assays illuminated that the strain YC-RL4 was of higher hydrophobicity while grown on DEHP and CSH increased with the higher DEHP concentration. The degradation rates of DEHP by strain YC-RL4 in different environmental samples was around 62.0 to 83.3% and strain YC-RL4 survived well in the soil sample. These results suggested that the strain YC-RL4 could be used as a potential and efficient PAE degrader for the bioremediation of contaminated sites.

Enhanced HO[rad] production from ozonation activated by EDTA

Activation of ozone for water treatment in acidic solution is challenging due to the lack of efficient initiators (e.g., HO−). Here, we report a marked enhancement of HO production from ozone at acidic pHs by EDTA. EDTA significantly accelerated the degradation of benzoic acid (BA), an HO probe, by ozonation in the pH range of 2.3–5.5, with higher efficiency than the O3/H2O2 process. Such enhancement was less dependent on temperature compared to the O3 or O3/H2O2 processes. The O3 decay and BA degradation kinetics were both highly dependent on the EDTA concentration. At an O3 dosage of 1.0mg/L and pH 2.3, Rct(∫OHdt/∫O3dt) was significantly increased by 8–50times with increasing the EDTA concentration from 1.0 to 40μM. The enhanced HO production was further confirmed by electron paramagnetic resonance, with the HO yield at ∼14.4%. Continuous batch runs were performed with the initial addition of EDTA only, and a similar enhancement effect was observed during cyclic runs. A plausible mechanism involving the formation of organonitrogen intermediates and nitrogen- or carbon- centered radicals is proposed to interpret the HO generation in the system. This study sheds new light on the activation of ozone at acidic pHs, and is believed to broaden the scope of ozonation in water treatment.

Enhancement photo-catalytic degradation of benzoic acid using the heterosystem NiCo2O4/ZnO

The present work focused on the degradation of benzoic acid in aqueous solutions using the heterosystem NiCo2O4/ZnO as a semi-conductor. The material NiCo2O4 is prepared by a nitrate method and characterized by several techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), reflectance diffuse (RD), electrical conductivity and the photo-electrochemical (PEC) characterizations. Under visible light, the benzoic acid degradation using a heterosystem NiCo2O4/ZnO is investigated. Several parameters are examined as the pH, the heterosystem ratio and the initial benzoic acid concentration. The results reveal that, as pH value increased from 2 to 6, the photo-degradation raised and the removal efficiencies attend the value 71%. The optimum results exhibited an enhancement photo-activity at a neutral pH and with a heterosystem ratio 50/50. The high efficiency is due to the present of unique structure constructed which increases the amount of electro-active sites and facilitates the electrolyte penetration via the electron transfer. Thus, the kinetic analysis showed that the photo-degradation rates can be approximated to be pseudo-first order, according to the Langmuir–Hinshelwood kinetics model.

Electrochemical treatment of benzoic acid (BA) from aqueous solution and optimization of parameters by response surface methodology (RSM)

The present research work is based on the degradation of benzoic acid (BA) and chemical oxygen demand (COD) from laboratory prepared aqueous solution. An electrocoagulation approach using aluminum (Al) and iron (Fe) as electrode material is applied in this study. A full factorial (4-factors, 5-level, and 3-response) rotatable central composite design in response surface methodology was developed for optimization of process parameters. Operating parameters such as pH (4–12), current density (A/m2)—(76.00–230.00), electrolysis time (min)—(15–90) and electrolyte concentration (NaCl) (g/L)—(0.5–1.5) are chosen for the study. Maximum % removal efficiency of BA—70.52, 64.42; COD—65.65, 60.70 and E. consumption (kWh/kgCODremoved)—102.89, 133.52 are achieved at optimal operating conditions by Al and Fe electrodes respectively. Sludge samples generated after EC treatment at optimum treatment conditions are also analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, TGA/DTA (thermo gravimetric analysis and differential thermo gravimetric analysis, FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction). Settling characteristics of sludge samples are also studied for both Al and Fe electrodes.

Role of the crystallite phase of TiO2 in graphene/TiO2 photocatalysis

Using chemisorption followed by annealing at different temperatures, TiO2 with different phases (anatase, rutile and mixed anatase/rutile) have been successfully assembled onto graphene sheet. The corresponding UV and visible induced photoactivities were evaluated using sensitized methyl orange and non-sensitized benzoic acid degradation as a probe reaction. The photocatalytic activities of TiO2 could be enhanced after assembled with graphene under UV and visible light irradiation both. However, Due to different charge transfer mechanism in UV and visible light irradiation system, the different crystallite phases of TiO2 acted different roles, hence displayed hierarchical enhancement phenomenon.

Self-enhanced ozonation of benzoic acid at acidic pHs

Ozonation of recalcitrant contaminants under acidic conditions is inefficient due to the lack of initiator (e.g., OH−) for ozone to produce hydroxyl radicals (HO). In this study, we reported that benzoic acid (BA), which is inert to ozone attack, underwent efficient degradation by ozone at acidic pH (2.3). The kinetics of BA degradation and ozone decomposition were both enhanced by increasing BA concentrations. Essentially, it is a HO-mediated reaction. Based on the exclusion of possible contributions of H2O2 and phenol-like intermediates for HO production, the reaction mechanism involved the formation of ozone ion (O3·−), which is an effective precursor of HO, was thus proposed. The hydroxycyclohexadienyl-type radicals generated during the attack of BA by HO may lead to the formation of O3·−. Meanwhile, O3·− could also be possibly formed from the reaction between ozone and organic (e.g., ROO∙) or inorganic peroxyl radicals (e.g., HO2). In addition, the hydroxylated products like phenol-like intermediates also played a positive role in HO production. Consequently, HO was produced efficiently under acidic conditions, resulting in rapid degradation of BA. This study provides a new approach for ozone activation even at acidic pHs, and broadens the knowledge of ozonation in removal of micropollutants from water.

Photoelectrocatalytic degradation of benzoic acid using Au doped TiO2 thin films

Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained.

Photoelectrocatalytic degradation of benzoic acid using sprayed TiO2 thin films

Transparent TiO2 thin films have been sucessfully synthesized by chemical spray pyrolysis technique. The effect of substrate temperature on the photoelectrochemical (PEC), structural, morphological, optical and photoelectrocatalytic properties has been investigated. The PEC study shows that both short circuit current (Isc) and open circuit voltage (Voc) at the optimized substrate temperature (450°C) are relatively maximum (Isc=1.7mA and Voc=770mV). The tetragonal crystal structure has been confirmed from X-ray diffraction patterns. FE-SEM study reveals that the film surface is changed from nanogranular to nanorod like morphology. The films exhibit a transmittance of about 80% in the visible region and a sharp absorption edge at 375nm corresponding to the fundamental absorption edge in UV region. Band gap energy varies from 3.33 to 3.43eV with substrate temperature. Electron-phonon coupling present in TiO2 films has been analyzed using Raman spectroscopy. The elemental composition and valence states of TiO2 film are studied by using X-ray photoelectron spectroscopy. The effect on the photoelectrocatalytic behavior of the large surface area (64cm2) TiO2 photocatalyst samples were studied by using photoelectrocatalytic degradation of benzoic acid under UV light illumination.

Facile preparation of Sn-doped BiOCl photocatalyst with enhanced photocatalytic activity for benzoic acid and rhodamine B degradation

A series of Sn-doped BiOCl photocatalysts were successfully synthesized at room temperature via a facile oxidation-reduction method. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoemission spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS) and photoluminescence (PL) emission spectroscopy measurements. The results showed that the as-prepared samples exhibited tetragonal crystal structure, lamellar morphology and band gap energy of 3.12eV and 2.91eV for BiOCl and Sn(10%)-doped BiOCl, respectively. XPS results showed that Sn was in the form of tetra-valence. The photocatalytic activities of as-synthesized samples were evaluated by the degradation of benzoic acid (BA) and rhodamine B (RhB) in an aqueous solution. The results revealed that the Sn doping could enhance the photocatalytic performance of BiOCl and the highest photocatalytic activity was achieved by the Sn(10%)-doped BiOCl, in addition, the optimum dosage of Sn(10%)-doped BiOCl was 0.4mg/L in degrading BA. The improved photocatalytic activity of Sn-doped BiOCl could be attributed to the narrower band gap energy (2.91eV) than pure BiOCl. Furthermore, scavenger experimental results indicated that h+ played the pivotal role in BA photocatalytic degradation. What is more, the as-synthesized Sn(10%)-doped BiOCl photocatalyst exhibited a good stability during the photodegradation of BA and RhB, revealing its promising prospect in the practical application of the treatment of organic wastewaters.

Photoelectrocatalytic activity of ferric oxide nanocatalyst: A synergestic effect of thickness

The Fe2O3 thin films have been deposited using ferric trichloride precursor at an optimized substrate temperature and concentration by simple chemical spray pyrolysis technique. Effect of quantity of the spraying solution on physicochemical properties of Fe2O3 thin films has been studied. Photoelectrochemical technique was used to optimize the quantity of a spraying solution. The PEC study shows that, Fe2O3 films are photoactive with relatively higher values of Isc=34.2μA and Voc=190mV respectively at 50ml quantity (thickness ~239nm). Effects of thickness on crystalline structure, morphology and optical properties have been studied. X-ray diffraction study confirms that the films are polycrystalline with rhombohedral crystal structure. The SEM and AFM micrographs depicts that the films are compact and needle shaped grains with grain size ~160–250nm. The direct band gap energy of Fe2O3 thin films is found to be in the range of 2.16–2.47eV. Four characteristic luminescence peaks having near band-edge, violet, blue and green emission are observed in the photoluminescence spectra. Photocatalytic degradation of benzoic acid by using Fe2O3 photoelectrode under visible light illumination has been investigated. The amount of mineralization is confirmed by COD and TOC analysis.

The Roles of Reactive Species in Micropollutant Degradation in the UV/Free Chlorine System

The UV/free chlorine process forms reactive species such as hydroxyl radicals (HO(•)), chlorine atoms (Cl(•)), Cl2(•-), and O(•-). The specific roles of these reactive species in aqueous micropollutant degradation in the UV/chlorine process under different conditions were investigated using a steady-state kinetic model. Benzoic acid (BA) was chosen as the model micropollutant. The steady-state kinetic model developed fitted the experimental data well. The results showed that HO(•) and Cl(•) contributed substantially to BA degradation, while the roles of the other reactive species such as Cl2(•-) and O(•-) were negligible. The overall degradation rate of BA decreased as the pH increased from 6 to 9. In particular, the relative contributions of HO(•) and Cl(•) to the degradation changed from 34.7% and 65.3% respectively at pH 6 to 37.9% and 62% respectively at pH 9 under the conditions evaluated. Their relative contributions also changed slightly with variations in chlorine dosage, BA concentration and chloride concentration. The scavenging effect of natural organic matter (NOM) on Cl(•) was relatively small compared to that on HO(•), while bicarbonate preferentially reduced the contribution of Cl(•). This study is the first to demonstrate the contributions of different reactive species to the micropollutant degradation in the UV/chlorine system under environmentally relevant conditions.

Rapid Acceleration of Ferrous Iron/Peroxymonosulfate Oxidation of Organic Pollutants by Promoting Fe(III)/Fe(II) Cycle with Hydroxylamine

The reaction between ferrous iron (Fe(II)) with peroxymonosulfate (PMS) generates reactive oxidants capable of degrading refractory organic contaminants. However, the slow transformation from ferric iron (Fe(III)) back to Fe(II) limits its widespread application. Here, we added hydroxylamine (HA), a common reducing agent, into Fe(II)/PMS process to accelerate the transformation from Fe(III) to Fe(II). With benzoic acid (BA) as probe compound, the addition of HA into Fe(II)/PMS process accelerated the degradation of BA rapidly in the pH range of 2.0-6.0 by accelerating the key reactions, including the redox cycle of Fe(III)/Fe(II) and the generation of reactive oxidants. Both sulfate radicals and hydroxyl radicals were considered as the primary reactive oxidants for the degradation of BA in HA/Fe(II)/PMS process with the experiments of electron spin resonance and alcohols quenching. Moreover, HA was gradually degraded to N2, N2O, NO2 (−), and NO3 (−), while the environmentally friendly gas of N2 was considered as its major end product in the process. The present study might provide a promising idea based on Fe(II)/PMS process for the rapid degradation of refractory organic contaminants in water treatment.

Li–Y doped and codoped TiO2 thin films: Enhancement of photocatalytic activity under visible light irradiation

Sol−gel synthesis based on the self-assembling template method has been applied to synthesize Li–Y doped and co-doped TiO2 not only to improve simultaneously the structural and electronic properties of TiO2 nanomaterials but also to achieve Li–Y doping of titania with high photocatalytic reactivity. The characterization of the samples was performed by GXRD, GSDR, FT-IR, and Raman spectroscopy. According to the GXRD patterns, all the observed reflections can be indexed using the anatase form of TiO2, Which is confirmed by ground state diffuse reflectance and micro-Raman spectra. The Li–Y doped titania materials immobilized as nanostructured thin films on glass substrates exhibit high photocatalytic efficiency for the degradation of toluidine and benzoic acid under visible light irradiation. The development of these visible light-activated nanocatalysts has the potential of providing environmentally benign routes for water treatment.

Co-catalysis effect of different morphological facets of as prepared Ag nanostructures for the photocatalytic oxidation reaction by Ag–TiO2 aqueous slurry

This paper highlights the comparative co-catalytic efficiency of different shapes of prepared Ag nanoparticles of size much larger as well as smaller than titania for the Ag–TiO2 photocatalysis. Quantum sized Ag nanospheres (4_8 nm), nanorod (length 70–75 nm and width 30–38 nm), polygonal nanosphere (80–120 nm) and truncated triangles (side length 70–140 nm) are prepared by solvothermal process. The co-catalytic activities of these Ag nanostructures were investigated by mixing them with TiO2 for the photocatalytic degradation of aqueous salicylic (0.5 mM) and benzoic acid (0.5 mM) under UV light (125 W-Hg arc, 10.4 mW cm−2) irradiation. The Ag co-catalysis effect imparted to TiO2 follows as polygonal nanosphere > nanorod > truncated triangle > small nanosphere due to the formation of many Ag–TiO2 interfaces by a single large-sized Ag nanoparticle than smaller one. As the surface coverage of Ag particles by TiO2 decreases, the Ag–TiO2 photoactivity is decreased accordingly. The efficient adsorption of salicylic acid to TiO2 surface through –COOH and –OH groups render its higher photodegradation rate (1.8–2.7 × 10−2 μmol min−1) than benzoic acid (1.5–2.5 × 10−2 μmol min−1) having one chelating –COOH group. Zeta potential and conductance measurement of photoreaction mixture were carried out to investigate the ionic interaction-adsorption of reactant substrates over Ag–TiO2 surface.