Atrazine In Aqueous Solution Research Articles

Remediation of atrazine contaminated soil with the help of hydrothermal carbon/diatomite composite inoculated with degrading microorganisms

Atrazine (ATZ) is a potent herbicide for annual broadleaf weeds, but it remains in the soil for a long time, causing serious phytotoxicity to subsequent crops, especially in maize fields. In this study, hydrothermal carbon was prepared from waste mushroom substrate and mixed with diatomite to serve as a microbial medium for culturing Arthrobacter sp. NJ-1, aiming to synergistically remediate ATZ-contaminated soil. When the ratio of hydrothermal carbon to diatomite was 3:2, the removal efficiency of ATZ in aqueous solution was the best-up to 81.67 %. The growth analysis of NJ-1 under different treatments revealed that the concentration of NJ-1 cultured with hydrothermal carbon/diatomite composite (MHS) was significantly higher than that of other combinations. Moreover, the application of MHS in conjunction with Arthrobacter sp. NJ-1 in ATZ-contaminated soil resulted in the removal of 92.52 % of ATZ residues. Additionally, this treatment significantly improved the physicochemical properties of the soil and enhanced soil fertility. The results of pot experiments showed that, compared to the control group plants significantly affected by ATZ pollution, the growth status of the experimental group plants improved after treatment with MHS synergistic Arthrobacter sp. NJ-1 system. These findings provide effective technical support and a theoretical basis for the remediation of ATZ-contaminated soil.

Enhancing the Photocatalytic Activity of Immobilized TiO2 Using Laser-Micropatterned Surfaces

In the past, the application of TiO2 slurry reactors has faced difficulties concerning the recovery and reusability of the catalyst. In response to these challenges, immobilized photocatalyst systems have been investigated, wherein the catalyst is fixed onto a solid support, frequently with reduced photocatalytic performance. In the present study, thin TiO2 films were developed in the anatase phase by the sol-gel process and spin-cast on laser-microstructured silicon substrates, to form photocatalytic surfaces of increased activity. The TiO2 films were thoroughly characterized using SEM-EDX, XRD, UV–Vis spectroscopy, and Raman spectroscopy. The photocatalytic activity of these surfaces was evaluated by the degradation of atrazine in aqueous solution under UV irradiation. Their photocatalytic activity was found to be significantly enhanced (mean kobs 24.1 × 10−3 min−1) when they are deposited on laser-microstructured silicon compared with flat silicon (mean kobs 4.9 × 10−3 min−1), approaching the photocatalytic activity of sol-gel TiO2 fortified with Degussa P25, used as a reference material (mean kobs 32.7 × 10−3 min−1). During the photocatalytic process, several transformation products (TPs) of atrazine, namely 2-chloro-4-(isopropylamino)-6-amino-s-triazine (CIAT), 2-chloro-4-amino-6-(ethylamino)-s-triazine (CAET), and 2-chloro-4.6-diamino-s-triazine (CAAT), were identified with LC–MS/MS. The stability of the photocatalytic surfaces was also investigated and remained unchanged through multiple cycles of usage. The surfaces were further tested with two other pollutants, i.e., 2,4,6-trichlorophenol and bisphenol-a, showing similar photocatalytic activity as with atrazine.

Preparation and characterization of EI-Co/Zr@AC and the mechanisms underlying its removal for atrazine in aqueous solution.

Atrazine, a widely used herbicide in agriculture, is detrimental to both the ecological environment and human health owing to its extensive use, poor degradability, and biotoxicity. The technology commonly used to remove atrazine from water is activated carbon adsorption, but it has the problems of difficult recovery, secondary contamination, and a low removal rate. To efficiently remove atrazine from agricultural wastewater, in this study, a new environmental material, embedding immobilization (EI)-Co- and Zr-modified activated carbon powder (Co/Zr@AC), was prepared by immobilizing the bimetallic Co/Zr@AC via EI technique and employed to remove atrazine. When preparing EI-Co/Zr@AC, the single-factor experiment was conducted and determined the optimal preparation conditions: sodium alginate 2.5% (wt), calcium chloride 4.0% (wt), Co/Zr@AC 1.0% (wt), and bentonite 2.0% (wt). The prepared EI-Co/Zr@AC has a three-dimensional mesh structure and many pores and also possesses good mass transfer performance and mechanical properties. The removal efficiency by EI-Co/Zr@AC for the removal of 5.0 mg/L atrazine from 50 mL was 94.1% at pH 7.0 and 25°C, with an EI-Co/Zr@AC dosage of 0.8 g. The mechanistic study showed that the pseudo-second-order kinetic model could describe the removal process better than the pseudo-first-order kinetic model, and the Freundlich isotherm model fit better than other isotherm models. Additionally, the synthesized EI-Co/Zr@AC spheres demonstrated good reusability, with the atrazine removal rate remaining 70.4% after five cycles, and the mechanical properties of the spheres were stable.

Characterization of Montmorillonite–Biochar Composite and Its Application in the Removal of Atrazine in Aqueous Solution and Soil

Atrazine is a widely used triazine herbicide, which poses a serious threat to human health and aquatic ecosystem. A montmorillonite–biochar composite (MMT/BC) was prepared for atrazine remediation. Biochar samples were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectrometer (XPS). Structural and morphological analysis of raw biochar (BC) and MMT/BC showed that MMT particles have been successfully coated on the surface of biochar. Sorption experiments in aqueous solution indicated that the MMT/BC has higher removal capacity of atrazine compared to BC (about 3.2 times). The sorption of atrazine on the MMT/BC was primarily controlled by both physisorption and chemisorption mechanisms. The amendment of MMT/BC increased the sorption capacity of soils and delayed the degradation of atrazine. Findings from this work indicate that the MMT/BC composite can effectively improve the sorption capacity of atrazine in aquatic environment and farmland soil and reduce the environmental risk.

Photocatalytic degradation of atrazine in aqueous solution using La-doped ZnO/PAN nanofibers.

Polyacrylonitrile (PAN)-based-modified zinc oxide (ZnO) nanofibers were synthesized by using electrospinning and hydrothermal techniques. The synthesized nanofibers were characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy and evaluated for their ability to promote the photocatalytic degradation of the toxic herbicide atrazine. The degradation conditions were optimized by varying catalyst types, catalyst quantity, pH, light source, and toxic concentration. The degradation products were confirmed by high-performance liquid chromatography and gas chromatography-mass spectrometry (GC-MS) analyses. The extent of mineralization was calculated using total organic carbon and real-time analyses. The diameter of the La-doped ZnO-loaded PAN nanofibers was larger than that of the ZnO-seeded PAN nanofibers. The additional peak at a binding energy of 533eV in the bonding states of La-doped ZnO/PAN indicated the presence of oxygen vacancies in the ZnO matrix, which could enhance the catalytic activity of the material. Furthermore, the degradation of atrazine depended on all the above reaction parameters. The mass spectrum of the degradation product was recorded and exhibited a molecular ion peak at m/z 187 according to GC-MS. Finally, La-doped ZnO PAN nanofibers proved to be an excellent catalyst for decontaminating atrazine within 1h and allowed to achieve a 98% degradation efficiency.

Microwave assisted synthesis of porous carbon from graphene for enhanced adsorption of atrazine in aqueous solution

Microwave assisted synthesis of porous carbon from graphene for enhanced adsorption of atrazine in aqueous solution

Extensive incorporation of carboxyl groups into g-C3N4 by integrated oxygen doping and HNO3 oxidation for enhanced catalytic ozonation of para-chlorobenzoic acid and atrazine

Carbon nitride (CN), oxygen-doped carbon nitride (CNO), HNO3 oxidized CN (CN-10) and CNO (CNO-10), were synthesized and used to catalyze ozonation of para-chlorobenzoic acid (p-CBA) and atrazine in aqueous solution. Pre-doping oxygen atom into CN could create extra defects for grafting more carboxyl groups during HNO3 oxidation, which was verified by much lower formation energy of CNO-10 than that of CN-10. Density functional theory and room temperature electron paramagnetic resonance (EPR) analysis signified the changes of electronic structure afforded by extensively grafted carboxyl groups. The incorporation of carboxyl groups distorted the carbon nitride framework and changed the spatial dimensions of CN and CNO, which attenuated the characters of delocalized π-electrons in conjugated structure. Moreover, the introduction of carboxyl groups reduced the pore diameter and nano-size distributed in aqueous solution for CN-10 and CNO-10 relative to those of CN and CNO. Results showed that the elimination efficiency of p-CBA by catalytic ozonation and Rct (standard reactivity metric for catalytic ozonation process) with CNO-10 improved 1.12- and 1.48-fold relative to those with CN-10, respectively, far surpassing non-catalytic ozonation. The removal of ozone-resisted compounds by CNO-10 catalyzed ozonation was not significantly affected by bicarbonate and NOM, and it was promoted by natural surface water resulting in 87.4% p-CBA removal in 30 min. Mechanistic evaluation demonstrated that carboxyl groups were the main active sites, catalyzing ozone decomposition into hydroxyl radical through radical chain reaction. This work provides fundamental supportive of pre-doping oxygen atom into CN before HNO3 functionalization, which could incorporate more carboxyl groups on surface compared to conventional strategy, further enhancing catalytic activity in ozonation.

Photocatalytic degradation of atrazine in aqueous solution using hyperbranched polyethyleneimine templated morphologies of BiVO4 fused with Bi2O3

Conventional methods have been reported to fail to completely remove contaminants of emerging concern (CECs) during wastewater treatment. Thus, new methods are required to improve wastewater treatment to completely remove the CECs from water. In this paper, we present the degradation of atrazine in aqueous solution using heterojunctions of BiVO4 and Bi2O3 that were synthesized from different morphologies of BiVO4 (truncated octahedron, plate-like, and platelet-like). The nanoparticles (NPs) were characterized using a scanning electron microscope, X-ray diffraction, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. It was observed that the heterojunctions were successfully synthesized and the observed morphologies for the BiVO4 were truncated octahedron, plate-like and platelet-like. The most effective heterojunction in the removal of atrazine was 0.5NaCl-BiVO4-Bi2O3. The 0.15HPEI-0.5NaCl-BiVO4-Bi2O3 had a reduced reaction rate compared to 0.5NaCl-BiVO4-Bi2O3, even though characterization showed that it was expected to be the most effective of all the NPs. The degradation of atrazine proceeded through dehalogenation, followed by the dealkylation and further deamination into cyanuric acid, a stable and less toxic compound. Data from LCMS/MS showed the formation of hydroxyatrazine, desethylhydroxyatrazine, and ammeline as intermediates. The degradation of several concentrations of atrazine revealed that the heterojunction efficiently removed >90 % of atrazine.

Preparation, activity, and mechanism of ZnIn2S4-based catalysts for photocatalytic degradation of atrazine in aqueous solution

Atrazine in aquatic environment poses a potential threat to human health and ecological system, and photocatalytic technology exhibits a promising prospect for eliminating trace pollutants in water. Four photocatalysts, ZnI2S4 (ZIS) and other three ZIS-based catalysts, g-C3N4/ZIS (CZIS), BiOBr/ZIS (BZIS)and Pd-ZIS (PZIS), were prepared by a facile hydrothermal method and characterized by BET, UV–vis DRS, SEM, TEM, XRD and XPS, respectively. It showed that four catalysts had high photocatalytic activities for atrazine degradation under different light sources irradiation, and their active sequence was PZIS < CZIS < ZIS < BZIS. The stronger light intensity the higher photocatalytic efficiency. Under direct solar irradiation of 1 h, the degradation efficiency for 20 mg/L of atrazine solution reached 90 % by PZIS with a dosage of 0.5 g/L. Pd doping increased the specific surface area and shortened the band gap and particle size of the catalyst that resulting in an effective enhancement of photocatalytic activity in the process of atrazine degradation. It confirmed by laser that Pd2+ ion entered the internal structure of ZIS to affect the crystal phase slightly but prohibit the recombination of photogenerated electron-hole pairs effectively. A feasible photocatalytic mechanism of atrazine by PZIS was proposed in the paper. The research work verified high photocatalytic activity of PZIS for its further application in the purification of aquatic environment that polluted by various herbicides including atrazine.

Degradation of atrazine in aqueous solution through peroxymonosulfate activated by Co-modified nano-titanium dioxide.

Peroxymonosulfate (PMS) heterogeneous activation by Co3 O4 -modified catalyst has shown significant implications to generate free radicals for organic pollutants degradation in water. In this study, PMS heterogeneous activation was applied to degrade atrazine (ATZ) using Co3 O4 -mediated titanium dioxide nanoparticles (Co3 O4 /TiO2 NPs), which were synthesized by sol-gel method. Firstly, characteristics of the fresh and used Co3 O4 /TiO2 NPs were analyzed via SEM, TEM, XRD, EDS, and XPS techniques. Then, the influences of several key parameters (i.e., Co3 O4 /TiO2 NPs dose (0.02-0.3g/L), PMS dose (0-0.6mM), initial pH (3.0-11.0), and co-existing anions) on the ATZ degradation were investigated systematically. Besides, control systems were set up to verify the high efficiency of Co3 O4 /TiO2 NPs. In addition, the radical scavenging experiments revealed that sulfate and hydroxyl radicals were generated in the Co3 O4 /TiO2 -PMS system, while sulfate radicals were the dominant reactive species responsible for ATZ degradation. Furthermore, the stability and reusability of the Co3 O4 /TiO2 NPs were investigated after four consecutive experiments. Based on the identified products, possible degradation pathways of ATZ in the Co3 O4 /TiO2 -PMS system were proposed. Finally, the possible reaction mechanism of Co3 O4 /TiO2 -PMS system was proposed according to the comprehensive analysis. Findings of this study provided useful information for the application of Co3 O4 /TiO2 NPs in recalcitrant organic contaminants degradation. PRACTITIONER POINTS: Co3 O4 /TiO2 NPs were synthesized via the simple sol-gel method. Co3 O4 /TiO2 NPs possessed excellent catalytic performance for PMS to eliminate ATZ. Sulfate radicals play a dominant role in the degradation of ATZ. ATZ degradation pathways and reaction mechanism in the system were proposed.

Transformation of atrazine by photolysis and radiolysis: kinetic parameters, intermediates and economic consideration

Four techniques, UV254 nm photolysis, vacuum ultraviolet (VUV172 nm) photolysis, combined UV254 nm/VUV185 nm photolysis and gamma (γ) radiolysis were used to induce the transformation of atrazine in aqueous solution. The effects of dissolved oxygen (atrazine concentration 1 × 10-4molL-1 and 4.6 × 10-7molL-1) and matrix (high purity water/purified wastewater, atrazine concentration 4.6 × 10-7molL-1) and the electric energy requirements were investigated. The calculation of the energy input in cases of the photolyses was based on the lamp's power. In radiolysis, the absorbed dose (Jkg-1) was the basis. In UV photolysis, atrazine transforms to atrazine-2-hydroxy; this product practically does not degrade during UV photolysis; due to this reason, the mineralisation is very slow. This and some other products of atrazine decomposition degrade only in radical reactions. Dissolved oxygen usually slightly enhances the degradation rate. At 10-7molL-1 concentration level, the matrix, high purity water/purified wastewater, has not much influence on the degradation rates in UV photolysis and radiolysis. In the VUV and UV/VUV systems, considerable matrix effects were observed. Comparing the electric energy requirements of the four degradation processes, radiolysis was found to be the economically most feasible method, requiring 1-2 orders of magnitude less electric energy than UV/VUV, VUV and UV photolysis.

Influence of solution pH on degradation of atrazine during UV and UV/H2O2 oxidation: kinetics, mechanism, and degradation pathways.

The kinetics, degradation mechanism and degradation pathways of atrazine (ATZ) during sole-UV and UV/H2O2 processes under various pH conditions were investigated; the effects of UV irradiation time and H2O2 dose were also evaluated. A higher reaction rate was observed under neutral pH conditions in the UV only process. For the UV/H2O2 process, a higher reaction rate was observed in acidic solution and the degradation rate of ATZ firstly increased with the increase of concentration of H2O2 and then decreased when H2O2 concentration exceeded 5 mg L−1. In addition, qualitative and quantitative analyses of oxidation intermediates of ATZ in aqueous solution during the sole-UV and UV/H2O2 processes were conducted using UPLC-ESI-MS/MS. Ten kinds of dechlorinated intermediates were detected during sole-UV treatment under all five pH conditions. In contrast, the speciation of intermediates in the UV/H2O2 process varied dramatically with solution pH. Based on the analysis of ATZ oxidation intermediates, ATZ degradation pathways under different pH conditions were proposed for the sole-UV and UV/H2O2 processes. The results showed that the main degradation reactions of ATZ included dechlorination-hydroxylation, dechlorination-dealkylation, de-alkylation, deamination-hydroxylation, alkylic-oxidation of lateral chains, dehydrogenation-olefination, dechlorination-hydrogenation, dechlorination-methoxylation and dehydroxylation.

Adsorption of atrazine from aqueous solution using unmodified and modified bentonite clays

Properties of raw bentonite clay of Afuze in Edo state which are abundant and cheap bentonite mineral in Nigeria as adsorbents for the removal of atrazine in aqueous solution were investigated. The bentonite clay-types were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrophotometry and X-ray diffraction (XRD). Batch adsorption experiments were carried out to determine the equilibrium characteristics, thermodynamics and kinetics of the sorption processes. The data obtained were subjected to Langmuir, Freundlich and Temkin isotherm equations, while pseudo-first-order, pseudo-second-order rate equations, intra-particle diffusion and Elovich models were considered for kinetics and mechanism. The results showed that the adsorption processes were described by different isotherm models; they were all spontaneous (∆G ranges from − 938.34 to − 6263.58 kJ/mol) and exothermic (range of ∆H is − 252.73 to − 1057.08 kJ/mol), and with decreased randomness, ∆S (− 3.110 to − 0.581 J.mol/K). Pseudo-second-order kinetics model gave the better fit for all the sorption processes which implies physisorption process as the rate limiting step. Thus, bentonite clay-types can be used to adsorb atrazine.

Photo-transformation of atrazine in aqueous solution in the presence of Fe3+-montmorillonite clay and humic substances

As one of the most troublesome herbicides, the natural behavior of atrazine has drawn great attentions. Currently, most studies investigated the adsorption of atrazine on clay minerals and humic substances (HSs), whereas, the transformation of atrazine catalyzed by clay and HSs was still unknown. In the present study, photo-degradation of atrazine in the presence of Fe3+-montmorillonite and Suwannee river fulvic acid (SRFA) in aqueous solution was systematically studied. In the Fe3+-montmorillonite system, the hydroxyl radical (OH) induced removal of atrazine was strongly pH-dependent and the reaction rate increased with the decrease of pH. The presence of SRFA suppressed the atrazine degradation by Fe3+-montmorillonite at pH 3 but promoted its removal rate in the pH range of 4–6. Our results demonstrated that both OH and singlet oxygen are responsible for the degradation process in the Fe3+-montmorillonite/SRFA hybrid system. The degradation of atrazine followed the cleavage of the CN bonds in aliphatic chains of atrazine, and three major products, desethylatrazine, desisopropylatrazine and desethyldesisopropylatrazine were detected. The toxicity assessment showed that the toxicity of the reaction solution significantly decreased after the radical reactions, indicating that the transformation of atrazine on natural clay minerals with/without HSs could be considered as a detoxification pathway, which might be important to evaluate the environmental risk of atrazine in a natural system.

Synergistic enhancement of oxidative degradation of atrazine using combined electrolysis and ozonation

In the current study concurrent electrolysis and ozonation was compared with the processes applied separately to degrade the herbicide atrazine in aqueous solution at pH 2, 7, and 12. Ozone containing gas was injected at a rate of 0.3 L/min into an electrolysis reactor with a boron-doped diamond anode and stainless steel cathode operating with an anodic current density of 10 mA/cm2. When electrolysis and ozonation were applied together, the rate constant of atrazine degradation could not be explained simply from considering the processes when applied separately. In particular, at pH 7, the measured first-order rate constant was 0.3441 min−1, a rate 4.78 times as large as the estimated additive rate (0.072 min−1) from electrolysis and ozonation separately in the same conditions. Across the pH range, the rate constant increased from 0.0516 min−1 at pH 2 to 0.3441 min−1 at pH 7 and 0.3065 min−1 at pH 12. Use of tert-butanol as a radical scavenger elucidated that HO contributed to a majority of the reaction at pH 7 and 12. The increasing impact of HO was due to ozone decomposition into HO through reaction with hydroxide (OH−) in both the bulk solution and at the cathode. Through LC-QTOF-MS analysis, acetamide and imine transformation of atrazine’s alkyl groups were observed at pH 7 and initial dechlorination by HO to form hydroxyatrazine was observed at pH 12.

Low-temperature synthesis of δ-Bi2O3 hierarchical nanostructures composed of ultrathin nanosheets for efficient photocatalysis

Due to its highest conductivity of any oxide material, the delta phase of Bi2O3 (δ-Bi2O3) is recognized as one of the most technologically important materials for various applications, including photocatalysis. Nevertheless, the δ-Bi2O3 phase is not stable at room temperature. Herein, we demonstrate that δ-Bi2O3 can be synthesized at low temperature through a facile sol-gel route in the presence of metavanadate oxyanion (VO3−). The chemical state and local structure of V are investigated by synchrotron-based techniques, such as X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). Our findings demonstrate the critical role of VO3− in stabilizing the δ-Bi2O3 phase. The crystallinity of δ-Bi2O3 is dramatically increased by the addition of VO3−. In the absence of VO3−, amorphous product is obtained. The as-synthesized δ-Bi2O3 possesses 3D hierarchical nanostructures constructed by ultrathin nanosheets with a few nanometers thick (~5nm). The nanosheets are composed of ultrasmall nanoparticles in the range of 1–2nm in size. Such a unique hierarchitecture of δ-Bi2O3 allows efficient light utilization due to multiple reflections and scattering, indicated by its excellent photocatalytic activity for the degradation and mineralization of atrazine in aqueous solution.

Degradation of atrazine in aqueous solution with electrophotocatalytic process using TiO2−x photoanode

The present study investigates the efficiency of a sustainable treatment technology, the electrophotocatalytic (EPC) process using innovative photoanode TiO2−x prepared by a magnetron sputter deposition process to remove the herbicide atrazine (ATZ) from water. The coexistence of anatase and rutile were identified by X-ray diffraction (XRD) and the presence of oxygen vacancies reduce the value of the observed bandgap to 3.0 eV compared to the typical 3.2 eV TiO2, this reduction is concomitant with a partial phase transition which is probably responsible for the increase in photoactivity. The experimental results with an initial concentration of ATZ (100 μg L−1) show that more than 99% of ATZ oxidation was obtained after 30 min of treatment and reaction kinetic constant was about 0.146 min−1. This good efficiency indicates that EPC process is an efficient, simple and green technique for degradation of pesticides such as ATZ in water. The analysis with liquid chromatography technique permits to identify, quantify and see the evolution of ATZ by-products which are generated by dechlorination, dealkylation and alkylic-oxidation mechanisms. Finally, the possible pathways of ATZ degradation by hydroxyl radicals were proposed.

Dielectric barrier discharge plasma induced degradation of aqueous atrazine.

Degradation of herbicide atrazine in aqueous solution was investigated using a plate type dielectric barrier discharge (DBD) plasma reactor. DBD plasma was generated at the gas-liquid interface of the formed water film. At discharge time of 14min, atrazine was degradated effectively with a degradation rate of 99% at the discharge power of 200W. The experimental data fitted well with first-order kinetics and the energy efficiency for 90% degradation of atrazine (G value) was calculated, obtaining a rate constant of 0.35min(-1) and a G value of 1.27 × 10(-10)molJ(-1) (98.76mgkW(-1)h(-1)) at a discharge power of 200W, respectively. The addition of Fe(2+) increased the rate constant and G value dramatically, and a significant decrease of the rate constant and G value was observed with the addition of radical scavengers (tert-butyl alcohol, isopropyl alcohol, or Na2CO3). The generated aqueous O3 and H2O2 were determined, which promoted the degradation of herbicide atrazine. Dechlorination was observed and the experimentally detected Cl(-) was 1.52mgL(-1) at a discharge time of 14min. The degradation intermediates of atrazine were detected by means of liquid chromatography-mass spectrometry; dechlorination, hydroxylation, dealkylation, and alkyl oxidation processes were involved in the degradation pathways of atrazine.

Electron beam induced degradation of atrazine in aqueous solution

Herein, the radiolytic degradations of atrazine and cyanuric acid were performed via electron beam irradiation. The results demonstrated atrazine could be completely mineralized without any residue of cyanuric acid in aqueous solution. The degradation of atrazine followed the pseudo-first-order reaction kinetics. The studies in the presence of different radical scavengers (O2 and tert-butanol) indicated hydroxyl radicals were the main species for the decomposition of atrazine into cyanuric acid, while e−aq played vital role in the degradation of cyanuric acid. During the radiolysis processes of atrazine and cyanuric acid, some organic and inorganic intermediates were detected, implying dechlorination, dealkylation, and deamination occurred. On the basis of the effects of radicals and detected products, the potential radiolytic degradation pathways of atrazine via electron beam were proposed.

Kinetic Processes of Acute Atrazine Toxicity to Brachydanio rerio in the Presence and Absence of Suspended Sediments

Suspended sediments can decrease the apparent bio-concentration factor of organic pollutants through adsorption. However, whether this process also weakens the toxicity of organic pollutants to non-target aquatic organisms is not clear. Therefore, natural sediments were chosen as suspended sediment examples in this research applying atrazine as the target pollutant and Brachydanio rerio (more recently, Danio rerio (Zebrafish)) as the target organism to conduct acute toxicity experiments. The concentration of atrazine in aqueous solution was measured as a time series. Results show that without suspended sediments, the 96-h LC50 of atrazine to Brachydanio rerio is 29.06 mg/l at 95 % confidence interval (24.41 to 40.70 mg/l). For suspended sediments of 7500 and 15,000 mg/l, the LC50 (i.e., concentration resulting in 50 % mortality) equates to 30.74 and 39.51 mg/l, respectively, and the corresponding confidence intervals are between 27.17 and 40.91 mg/l and between 30.43 and 126.93 mg/l in that order. Probit analysis, which is a type of regression used to analyze binomial response variables, was applied using the Statistical Package for the Social Sciences. For the series of no suspended solids (SS), 7500 and 15,000 mg/l SS, the so-called no-observed-effective concentrations were 3, 9, and 15 mg/l, correspondingly. The uptake quantity and uptake rate of atrazine by B. rerio according to atrazine concentrations in the aqueous solution were computed. The research indicates that suspended sediments can decrease the absorbed rate of atrazine by B. rerio. Thus, suspended sediments weaken the acute toxicity of atrazine to B. rerio.