Atrazine Removal Research Articles

Experimental and computational studies of photoelectrochemical degradation of atrazine by modified nanoporous titanium dioxide

The presence of herbicides like Atrazine (ATZ) in groundwater from non-target runoff of the agriculture industry becomes a big concern due to its potential negative impacts on the environment and human health. The use of advanced oxidative processes (AOP) to remove harmful contaminants has been shown to be effective for wastewater treatment. Herein, we report on an advanced photoelectrochemical (PEC) approach based on electrochemically modified nanoporous TiO2 electrode for efficient degradation of ATZ. The electrochemical treated TiO2 electrodes were shown to have a six-fold increase in the photo-current density over the untreated ones. This increase in PEC activity was attributed to the increase in Ti3+ sites after the electrochemical modification, which was corroborated by low-temperature electron paramagnetic resonance (EPR) studies. The removal of ATZ by the PEC process resulted in a rate constant of 1.91 × 10−3 s−1, compared to 3.12 × 10−4 s−1 obtained by a strictly photocatalytic process. Liquid-Chromatography Mass-Spectrometric measurements showed the modified TiO2 electrodes highly effective at removing ATZ, with 96.1% removed after 10 h. Monitoring of the common degradation products desethyl atrazine (DEA), desisopropyl atrazine (DIA) and desethyl desisopropyl atrazine (DDA) revealed very low concentrations throughout the degradation process, indicating that further degradation was achieved. Quantum mechanical-based test for overall free radical scavenging activity (QM-ORSA) computational studies were performed and a mechanism for the N-dealkylation processes of ATZ has been proposed.

Characterization and novel pathway of atrazine catabolism by Agrobacterium rhizogenes AT13 and its potential for environmental bioremediation

Agrobacterium rhizogenes AT13, a novel bacterial strain that was isolated from contaminated soil, could utilize atrazine as the sole nitrogen, thereby degrading it. Optimization of the degradation reaction using a Box–Behnken design resulted in 99.94% atrazine degradation at pH 8.57, with an inoculum size of 3.10 × 109 CFU/mL and a concentration of 50 mg/L atrazine. Ultra-high performance liquid chromatography-electrospray ionization-high resolution mass spectrometry (UPLC-ESI-HRMS), liquid chromatography tandem mass spectrometry (LC-MS/MS) and high performance liquid chromatography (HPLC) analyses identified and quantified six reported metabolites and a novel metabolite (2-hydroxypropazine) from atrazine degradation by AT13. On the basis of these metabolites, we propose an atrazine degradation pathway that includes dichlorination, hydroxylation, deamination, dealkylation and methylation reactions. The toxicity of the degradation products was evaluated by Toxicity Estimation Software Tool (T.E.S.T). Bioaugmentation of atrazine-polluted soils/water with strain AT13 significantly improved the atrazine removal rate. Thus, AT13 has potential applications in bioremediation.

Atrazine biodegradation in water by co-immobilized Citricoccus sp. strain TT3 with Chlorella vulgaris under a harsh environment

With the extensive use of herbicides in agricultural production, the nearby waters are polluted by atrazine. The isolated Citricoccus sp. strain TT3 in our lab can transform atrazine into harmless cyanuric acid under natural conditions. However, this method is limited in practical use because of the weak resistance of bacteria to the harsh water environment. To solve this problem, Chlorella vulgaris was combined with atrazine degradation bacteria and co-immobilized in porous beads. The results demonstrated no significant difference in the atrazine removal rate between the free bacteria-microalgae mixture and the pure bacteria sample. Only 3.15 % and 4.35 % of atrazine in the acidic solution were removed by free bacteria and the bacteria-algae mixture. However, the degradation rate of immobilized bacteria and co-immobilized bacteria-microalgae under the same condition increased by 22.93 % and 40.57 %, respectively. Moreover, the inhibition effect of concomitant Mn2+, Cd2+, Co2+, and Cu2+ on the activity of Citricoccus sp. strain TT3 in beads was reduced. In addition, the long-term storage of immobilized beads still maintained a relatively stable degradation capacity, but its reusability needed to be improved. After being entrapped in microspheres, the enhancing effect of Chlorella vulgaris on the biodegradation of atrazine was pronounced under adverse environmental conditions. The study provided insight into the practical application of atrazine biodegradation technology.

Enhanced phytoremediation of atrazine-contaminated soil by vetiver (Chrysopogon zizanioides L.) and associated bacteria.

The intensive and long-term use of atrazine (ATZ) has led to the contamination of agricultural soils and non-target organisms, posing a series of threats to human health through the transmission of the food chain. In this study, a 60-day greenhouse pot experiment was carried out to explore the phytoremediation by Chrysopogon zizanioides L. (vetiver). The uptake, accumulation, distribution, and removal of ATZ were investigated, and the degradation mechanisms were elucidated. The results showed that the growth of vetiver was inhibited in the first 10 days of the incubation; subsequently, the plant recovered rapidly with time going. Vetiver grass was capable of taking up ATZ from the soil, with root concentration factor ranging from 2.36 to 15.55, and translocating to the shoots, with shoot concentration factor ranging from 7.51 to 17.52. The dissipation of ATZ in the rhizosphere soil (97.51%) was significantly higher than that in the vetiver-unplanted soil (85.14%) at day 60. Metabolites were identified as hydroxyatrazine (HA), deethylatrazine (DEA), deisopropylatrazine (DIA), and didealkylatrazine (DDA) in the samples of the shoots and roots of vetiver as well as the soils treated with ATZ. HA, DEA, DIA, and DDA were reported first time as metabolites of ATZ in shoots and roots of vetiver grown in soil. The presence of vetiver changed the formation and distribution of the dealkylated products in the rhizosphere soil, which remarkably enhanced the occurrence of DEA, DIA, and DDA. Arthrobacter, Bradyrhizobium, Nocardioides, and Rhodococcus were the major atrazine-degrading bacterial genera, which might be responsible for ATZ degradation in the rhizosphere soil. Our findings suggested that vetiver grass can significantly promote ATZ degradation in the soil, and it could be a strategy for remediation of the atrazine-contaminated agricultural soil.

Performance of a Combined Bacteria/Zeolite Permeable Barrier on the Rehabilitation of Wastewater Containing Atrazine and Heavy Metals

Several chemicals, such as pesticides and heavy metals, are frequently encountered together in environment matrices, becoming a priority concerning the prevention of their emissions, as well as their removal from the environment. In this sense, this work aimed to evaluate the effectiveness of a permeable biosorbent bio-barrier reactor (PBR) on the removal of atrazine and heavy metals (copper and zinc) from aqueous solutions. The permeable bio-barrier was built with a bacterial biofilm of R. viscosum supported on 13X zeolite. One of the aims of this work is the investigation of the toxic effects of atrazine, copper and zinc on the bacterial growth, as well as the assessment of their ability to adapt to repeated exposure to contaminants and to degrade atrazine. The growth of R. viscosum was not affected by concentrations of atrazine bellow 7 mg/L. However, copper and zinc in binary solutions were able to inhibit the growth of bacteria for all the concentrations tested (5 to 40 mg/L). The pre-acclimation of the bacteria to the contaminants allowed for an increase of 50% of the bacterial growth. Biodegradation tests showed that 35% of atrazine was removed/degraded, revealing that this herbicide is a recalcitrant compound that is hard to degrade by pure cultures. The development of a PBR with R. viscosum supported on zeolite was successfully performed and the removal rates were 85% for copper, 95% for zinc and 25% for atrazine, showing the potential of the sustainable and low-cost technology herein proposed.

Iron–doped bismuth oxybromides as visible−light−responsive Fenton catalysts for the degradation of atrazine in aqueous phases

Pesticides and its degradation products, being well–known residues in soil, have recently been detected in many water bodies as pollutants of emerging concerns, and thus there is a contemporary demand to develop viable and cost–effective techniques for the removal of related organic pollutants in aqueous phases. Herein, a visible−light−responsive Fenton system was constructed with iron–doped bismuth oxybromides (Fe–BiOBr) as the catalysts. Taking the advantage of sustainable Fe(III)/Fe(II) conversion and optimized H2O2 utilization, the optimal Fe–BiOBr–2 catalyst showed an excellent atrazine removal efficiency of 97.61% in 120 min, which is superior than the traditional homogeneous Fenton and the majority of heterogeneous processes documented in the literature. In this photo–Fenton system, hydroxyl (·OH) and superoxide (·O2–) radicals were dominant active species contributed to the oxidative degradation of atrazine. Due to the production of various active radicals, five degradation pathways were proposed based on the identification of intermediates and degradation products. Overall, this work not only demonstrates a fundamental insight into creating highly efficient and atom economic photo−Fenton systems, but also provides a complementary strategy for the treatment of organic pollutants in water.

Remediation of atrazine-polluted soil using dielectric barrier discharge plasma and biochar sequential batch experimental technology

Dielectric barrier discharge (DBD)-biochar sequential batch experimental technology was employed to degrade atrazine (ATZ) in soil. The hydrophilicity, particle size and instability of soil particles increased after DBD treatment, which contributed to the exposure of residual ATZ in the soil. Meanwhile, the subsequent introduction of biochar compensated for the shortcomings of sole DBD treatment (e.g. increased soil sparseness and pH, enhanced the living environment of microorganisms). The ATZ removal efficiency in air discharge reached 66.1 % after 10 min of DBD treatment and 30 min of biochar adsorption, and the energy yield was 4.2 times higher than that of sole DBD treatment. The functional active species in ATZ degradation were confirmed to be oxygen-containing reactive species. ATZ degradation mechanisms were proposed, including dealkylation, dechloro-hydroxylation, alkylic-hydroxylation, alkylic-oxidation, olefinization and deamino-hydroxylation reactions. Hence, the study demonstrated an environmentally friendly technology for effective ATZ degradation while improving the fertility of soil with no chemical injections.

Catalytic Biomaterials for Atrazine Degradation

In this paper, triazine hydrolase from Arthrobacter aurescens TC1 (TrzN) was successfully immobilized in alginate beads (TrzN:alginate), alginate beads coated in chitosan (TrzN:chitosan), and tetramethylorthosilicate (TMOS) gels using the sol–gel method (TrzN:sol–gel) for the first time. TrzN:alginate and TrzN:chitosan hydrolyzed 50 µM of atrazine in 6 h with negligible protein loss with an ~80% conversion rate. However, the TrzN:sol–gel biomaterial converted >95% of a 50 µM atrazine solution in an hour with negligible protein loss. The treatment of each of these biomaterials with trypsin confirmed that the catalytic activity was due to the encapsulated enzyme and not surface-bound TrzN. All three of the biomaterials showed potential for long-term storage and reuse, with the only limitation arising from the loss of protein in the storage buffer for the TrzN:alginate and TrzN:chitosan biomaterials, not the denaturation of the encapsulated TrzN. TrzN:sol–gel stood out, with ~100% activity being retained after 10 consecutive reactions. Additionally, the materials stayed active in methanol concentrations <10%, suggesting the ability to increase the solubility of atrazine with organic solvents. The structural integrity of the TrzN:alginate and TrzN:chitosan materials became limiting in extreme pH conditions, while TrzN:sol–gel outperformed WT TrzN. Overall, the TrzN:sol–gel biomaterial proved to be the best atrazine dichlorination biocatalyst. As sol–gels can be cast into any desired shape, including pellets, which can be used in columns, the TrzN:sol–gel biomaterial provides a new avenue for the design of bioremediation methodologies for the removal of atrazine from the environment.

The Atrazine Removal with the Polyaniline Coated Rice Husk as a Cheap Adsorbent

In this study, a composite of rice husk (RH) modified with polyaniline (PANI) was produced and its potential as an adsorbent in removal of atrazine was investigated.
 Within the scope of the study, the effects of contact time (0-480 min), initial pH (3.5-
 9.5), initial atrazine concentration (2-25 mg/L), and PANI/RH amount (0-1.6 g) on
 treatment efficiency were examined. The optimum treatment efficiency for atrazine
 (25 mg/L) was found as 58.3% under 120 min., 5.4 of pH, and 1.0 g/50 ml of
 adsorbent dosage, and at this condition, adsorption capacities (qt) was calculated as
 0.58 mg/g. Furthermore, when the initial atrazine concentration was raised from 2 to
 25 mg/L, the removal efficiencies decreased from 81.1 to 60.4 %, but the adsorption
 capacities (qt) increased from 0.067 to 0.629 mg/g. In addition, the efficiency of the
 adsorption process was evaluated by applying Langmuir and Freundlich isotherm
 models. Among the performed isotherm models, Freundlich isotherm provided the
 best correlation for atrazine and the Freundlich constant related to the sorption
 capacity was calculated as 2.02 mg/g at an initial pH of 5.4 for the 2.0-25 mg/L
 atrazine at 25 oC. Raw-PANI/RH and used-PANI/RH composites were characterized
 with FTIR, XRD, and SEM analysis.

Unveiling the origin of high-efficiency charge transport effect of C3N5/C3N4 homojunction for activating peroxymonosulfate to degrade atrazine under visible light

Photocatalytic activation of PMS is a potential advanced oxidation process in refractory wastewater purification. Herein, a C3N5/C3N4 homojunction (AT-CN) catalyst as an efficient photocatalyst for PMS activation is reported, which owns interlaced band structure, high-efficiency charge transfer, and PMS activation capability. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation. As experimental result, the reaction rate constants of atrazine in AT-CN/PMS/Vis system increased to 2.9-fold and 7.4-fold, compared with C3N4/PMS/Vis and C3N5/PMS/Vis system. The photocatalytic activation of PMS for atrazine removal efficiency reached 97 % within 60 min (under pH = 3). The band structure, the charge density difference, the PMS adsorption behavior of AT-CN, and the activation pathways of PMS have been studied through the DFT calculation. According to experimental and DFT simulation, the AT-CN homojunction not only suppress the charge recombination via built-in electric field, but also exhibited a better PMS activation capability. In brief, this study through the combination of experiment and simulation is providing more inspiration for designing appropriate nonmetal homojunction in the photo-activated PMS process.

MoS4-LDH: A dual centre Fe-based layered double hydroxide catalyst for efficient atrazine removal and peroxymonsulfate activation

The Fe-based materials were considered very attractive for the treatment of wastewater using peroxymonosulfate (PMS) activation. However, the difficulties to restore the active Fe2+ oxidation state restrict them to attained sustainable efficiency. In this work, a new strategy was introduced to accelerate the regeneration of Fe2+ state through constructing an electron-rich MoS42− centre in the inter-layers of FeMgAl layered double hydroxide (MoS4-LDH) catalyst. The dual centre MoS4-LDH catalyst was found more efficient as clear from the observed atrazine (ATZ) degradation rate of 0.117 min−1, 100 times higher than the Fe3+/PMS or 25–50 times higher than the Fe based single centre NO3-LDH/PMS, CO3-LDH/PMS or S2O4-LDH/PMS systems, respectively. This boosted efficiency was related to the electron-rich MoS42− centre which allows the constant electron transfer to reduce the electron-deficient Fe3+ center at MoS4-LDH surface and thereby accelerating the Fe2+/Fe3+ redox cycle during reaction. Furthermore, the MoS4-LDH/PMS system exhibited a broader effective pH (3.0–9.0), good stability and minimum influence of background electrolyte or organic matter. The degradation pathway of ATZ based on free radical (SO4– and OH), involving the redox cycles of Fe3+/Fe2+ and Mo6+/Mo4+ was proposed for the activation of PMS. This work highlighted the essential role of MoS42− moiety, to accelerate the Fe3+ reduction at the surface of the LDH catalyst through the continuous feeding of electrons.

Production and Characterization of Wild Sugarcane (Saccharum spontaneum L.) Biochar for Atrazine Adsorption in Aqueous Media

Wild sugarcane (Saccharum spontaneum L.) is an invasive plant species in the Central American region. Due to its low nutrient and water requirements, it can grow fast and displace native species. Therefore, its biomass is considered a waste to prevent the further distribution of the specie. This study investigates the production and characterization of wild sugarcane biochar to provide a use for its waste. The produced biochar was used for atrazine adsorption in aqueous solutions to provide a possible application of this biochar near the water bodies that were often detected to be contaminated with atrazine. The biochar was produced via top-lit updraft gasification with airflow rates between 8 to 20 L/min, achieving yields ranging from 22.9 to 27.5%. Batch experiments revealed that biochar made at 12 L/min presented the best removal efficiency (37.71–100%) and the maximum adsorption capacity (qm = 0.42 mg/g). Langmuir (R2 = 0.94–0.96) and Freundlich (R2 = 0.89–0.97) described the experimental data appropriately. Fourier transform infrared spectroscopy suggested that atrazine removal in wild sugarcane biochar could be mainly due to carboxylic functional groups. In addition, the biochar organic carbon composition contributed to a higher removal capacity in biochar produced at different airflow rates.

Intensified atrazine removal in a novel biochar coupled electrolysis-integrated bioretention system

Triazine herbicide (e.g., atrazine, ATZ) loss caused by road stormwater runoff is one of the most important non-point source pollutions. This study developed a biochar coupled electrolysis-integrated system (BC-EC-BRS), and its removal impact on ATZ under different initial concentration of ATZ, received runoff volume and rainfall intensity was investigated. Compared with the other three groups of bioretention systems, including a conventional system without biochar and electrolysis (BRS), an electrolysis-integrated system (EC-BRS), and a biochar amended system (BC-BRS), the ATZ removal rate in BC-EC-BRS was significantly increased to 90.26 %, roughly 40 % higher than BRS, indicating that electrolysis and biochar had a synergistic promotion impact on ATZ removal. However, due to the limitations inherent in the soil medium adsorption site and electron donor, the removal efficiency of ATZ in each system decreased with an increase in the initial concentration of ATZ and rainfall intensity, while the removal efficiency of ATZ in BC-EC-BRS is less affected. The main reason may be that under the presence of electrolysis, ATZ can be oxidized by direct electron transport or by OH adsorbed on the anode surface, and the resulting by-product hydroxyatrazine (HA) may mean that ATZ is more biodegradable in BC-EC-BRS. Iron ions in-situ supported on biochar (Fe@BC) were also achieved through electrolytic coupling, which enhanced its adsorption and electron transport ability. Furthermore, the coupling of biochar and electrochemistry can also indirectly impact the bacterial community structure and promote the growth of functional bacteria, such as Paenarthrobacter, Arthrobacter, and Bacillus, thus promoting the biodegradation of ATZ. BC-EC-BRS has excellent ATZ removal performance under the synergistic action of adsorption, electrolysis, and microbial degradation, which confirms that BC-EC-BRS is an effective control measure for ATZ removal from stormwater runoff.

Noval bio-organic fertilizer containing Arthrobacter sp. DNS10 alleviates atrazine-induced growth inhibition on soybean by improving atrazine removal and nitrogen accumulation

Herbicide atrazine restricts nutrient accumulation and thus inhibits the growth of sensitive crops. The application of organic fertilizer is a common measure that contributes to modulating abiotic tolerance of crops and providing nutrients, but its advantages in combination with atrazine degrading microorganisms as bio-organic fertilizer to alleviate atrazine stress on sensitive crops and the associated mechanisms are unknown. We investigated the beneficial effects of organic and bio-organic fertilizer (named DNBF10) containing Arthrobacter sp. DNS10 applications on growth, leaf nitrogen accumulation, root surface structure and root physiological properties of soybean seedlings exposed to 20 mg kg−1 atrazine in soil. Compared with organic fertilizer, bio-organic fertilizer DNBF10 exhibited more reduction in soil atrazine residue and plant atrazine accumulation, as well as alleviation in atrazine-induced root oxidative stress and damaged cells of soybean roots. Transcriptome analysis revealed that DNBF10 application enhanced nitrogen utilization by improving the expression of genes involved in nitrogen metabolism in soybean leaves. Besides, genes expression of cytochrome P450 and ABC transporters involved in atrazine detoxification and transport in soybean leaves were also down-regulated by DNBF10 to diminish phytotoxicity of atrazine to soybean seedlings. These results illustrate the molecular mechanism by which the application of DNBF10 alleviates soybean seedlings growth under atrazine stress, providing a step forward for mitigate the atrazine induced inhibition on soybean seedlings growth through decreasing atrazine residues as well as enhancing damaged root repair and nitrogen accumulation.

Electrochemical activation of persulfate by Al-doped blue TiO2 nanotubes for the multipath degradation of atrazine

The combination of electrolysis and persulfate activation (E/PDS) is a cost-effective method for the treatment of refractory organics. However, persulfate is difficult to be activated into radicals at the anode, resulting in insufficient electro-activation efficiency. Herein, Al doped blue TiO2 nanotube electrodes (Al-bTNT) were first employed as cost-effective anode materials to fully activate PDS to radicals. In E/PDS, the kinetic constant of atrazine removal by Al-bTNT (0.048 min−1) substantially outperformed the other anodes, including the blue TiO2 nanotube electrodes (bTNT) (0.024 min−1), Ti4O7 (0.02 min−1), and B doped diamond (BDD) anodes (0.023 min−1). The Al-bTNT-E/PDS exhibited a low energy consumption (EEO = 0.72 kWh m−3) and a high mineralization rate. Based on the results of electron paramagnetic resonance, quenching experiments, and probe experiments, we propose that atrazine degrades in the Al-bTNT-E/PDS system mainly via a novel radical pathway that involves both·OH and SO4·- and the generated SO4·- is responsible for the enhanced removal rate. The oxygen vacancies (VO) generated from interstitial Al may serve as the active sites to adsorb and dissociate the persulfate molecules based on extensive characterizations. The attempt at soil-washing wastewater disposal indicated the synergistic system possessed good potential for future practical application.

Adsorption of Atrazine by Fe-Mn-Modified Biochar: The Dominant Mechanism of π–π Interaction and Pore Structure

It is important to explore efficient materials to alleviate the negative effect of atrazine in soils or water. In this paper, four Fe/Mn-modified biochars were prepared to enhance atrazine removal. The batch adsorption experiment was conducted to explore the adsorption ability of biochar(DBC) and modified biochars (F3M1DBC, F1M3DBC, MnDBC, and FeDBC) on atrazine, and the adsorption mechanism was conducted by XRD, XPS, and FTIR. The modified biochar showed larger specific surface areas and zero-point charge than those of the original biochar. The increased oxygen functional groups (OH, C=C, and C=O) and the formation of Fe3O4, Mn3O4, and FeMnO3 on modified biochar improved atrazine removal. The maximum atrazine adsorption by F3M1DBC was 4.3 times higher than that of DBC. The atrazine adsorption by modified biochar was not pH-dependent, and their removal of atrazine was dominated by adsorption rather than degradation. The desorption rate was 8.61% for F3M1DBC, 15.95% for F1M3DBC, 26.19% for MnDBC, and 29.83% for FeDBC, which were 29.1–79.5% lower than that of DBC, accordingly decreased the environmental risk. XPS and FTIR analysis proved that the adsorption mechanisms of Fe/Mn-modified biochars were mainly attributed to their strong π–π interactions between atrazine and oxygen functional groups, graphitic carbon, and Fe/Mn-oxides on the surface of biochar. In addition, the larger surface area and pore structure of modified biochar contributed to the adsorption and pore filling of atrazine on biochar. In general, the Fe/Mn-modified biochars can be used as effective adsorbents to remove atrazine from soils and waters.

Use of wood and cork in biofilters for the simultaneous removal of nitrates and pesticides from groundwater

About 13% and 7% of monitored groundwater stations in Europe exceed the permitted levels of nitrates (50 mg NO3− L−1) or pesticides (0.1 μg L−1), respectively. Although slow sand filtration can remove nitrates via denitrification when oxygen is limited, it requires an organic carbon source. The present study evaluates the performance of the use of wood pellets and granulated cork as carbon sources in bench-scale biofilters operated under water-saturated and water-unsaturated conditions for more than 400 days. The biofilters were monitored for nitrate (200 mg L−1) and pesticide (mecoprop, diuron, atrazine, and bromacil, each at a concentration of 5 μg L−1) attenuation, as well as for the formation of nitrite and pesticide transformation products. Microbiological characterization of each biofilter was also performed. The water-saturated wood biofilter achieved the best nitrate removal (>99%), while the cork biofilters lost all denitrification power over time (from 38% to no removal). The unsaturated biofilter columns were not effective for removing nitrates (20–30% removal). As for pesticides, all the biofilters achieved high removal rates of mecoprop and diuron (>99% and >75%, respectively). Atrazine removal was better in the wood-pellet biofilters than the cork ones (68–96% vs. 31–38%). Bromacil was only removed in the water-unsaturated cork biofilter (67%). However, a bromacil transformation product was formed there. The water-saturated wood biofilter contained the highest number of denitrifying microorganisms, with Methyloversatilis as the characteristic genus. Microbial composition could explain the high removal of pesticides and nitrates achieved in the wood-pellet biofilter. Overall, the results indicate that wood-pellet biofilters operated under water-saturated conditions are a good solution for treating groundwater contaminated with nitrates and pesticides.

Insight into atrazine removal by fallen leaf biochar prepared at different pyrolysis temperatures: Batch experiments, column adsorption and DFT calculations

The environmental pollution caused by atrazine in the agricultural production cannot be ignored. In this study, the fallen leaf biochar (LBC) was prepared at three different temperatures (500 °C, 600 °C, and 700 °C) using a simple pyrolysis method (500 LBC, 600 LBC, and 700 LBC) for atrazine adsorption. Batch experiments showed that the performance of LBC in atrazine adsorption improved with rising pyrolysis temperature, and the highest adsorption amount of 700 LBC reached 84.32 mg g−1. Kinetic and isotherm models showed that the adsorption behaviors were both monolayer and multilayer chemisorption. The findings of the characterizations (Elemental analysis, BET, XRD, Raman, FT-IR, and XPS) confirmed that the degree of aromatization determined the adsorption capacity of LBC to atrazine, and π-π electron donor-acceptor interaction was the main adsorption mechanism. Density functional theory (DFT) calculations showed that the highly aromatized biochar was more effective for atrazine adsorption, manifested as smaller molecular distances, higher adsorption energies, more stable complex structures, and stronger π-electron conjugation. In the column adsorption experiments, reducing the inlet flow rate or increasing the bed height extended the breakthrough time and exhaustion time of the breakthrough curves, and 700 LBC still showed good adsorption performance after five cycles. Overall, fallen leaf biochar as a reuse product of resource showed good potential for application in atrazine adsorption, which can be used for atrazine-contaminated water remediation.

Amplification of oxidative elimination of atrazine by Ultrasound/Ultraviolet–assisted Sono/Photocatalyst using a spinel cobalt ferrite–anchored MWCNT as peroxymonosulfate activator

In this study, multi–walled carbon nanotubes–supported cobalt ferrite nanoparticles (CoFe2O4@MWCNTs) were synthesized by the co–precipitation method and applied to activate peroxymonosulfate (PMS) for Atrazine (ATZ) degradation. The highest degradation rates (99.99 % and 98.17 %) were obtained at pH 5.0, PMS dosage of 1 mM, catalyst dosage of 0.25 g/L, ATZ concentration of 20 mg/L, and temperature of 298 K. Quenching tests showed that the hydroxyl radical was the main agent in ATZ degradation. The ATZ removal efficiency was higher than 90 % even after five cycles, indicating that CoFe2O4@MWCNT nanocomposite is reusable. Under optimum conditions, 77.8 % and 86.7 % of total organic carbon (TOC) were removed after 60 min of being in US/CoFe2O4@MWCNT/PMS and UV/CoFe2O4@MWCNT/PMS systems. The synthesized catalyst can be a promising catalyst for the degradation of refractory organic pollutants, due to excellent catalytic activity, high reusability, and low ion leaching.

Mitigation of atrazine-induced oxidative stress on soybean seedlings after co-inoculation with atrazine-degrading bacterium Arthrobacter sp. DNS10 and inorganic phosphorus-solubilizing bacterium Enterobacter sp. P1.

Atrazine toxicity is one of the limiting factors inhibiting sensitive plant growth. Previous studies showed that atrazine-degrading bacteria could alleviate atrazine toxicity. However, there is limited information on how atrazine-degrading bacteria and plant growth-promote bacteria alleviate atrazine toxicity in soybeans. Therefore, the current study aimed to explore the atrazine removal, phosphorus utilization, and the oxidative stress alleviation of atrazine-degrading bacterium Arthrobacter sp. DNS10 and/or inorganic phosphorus-solubilizing bacterium Enterobacter sp. P1 in the reduction of atrazine toxicity in soybean. The results showed that atrazine exposure to soybean seedlings led to significant inhibition in growth, atrazine removal, and phosphorus utilization. However, the co-inoculatied strains significantly increased seedlings biomass, chlorophyll a/b contents, and total phosphorus in leaves accompanied by great reduction of the atrazine-induced antioxidant enzymes activities and malonaldehyde (MDA) contents, as well as atrazine contents in soil and soybeans under atrazine stress. Furthermore, transcriptome analysis highlighted that co-inoculated strains increased the expression levels of genes related to photosynthetic-antenna proteins, carbohydrate metabolism, and fatty acid degradation in leaves. All the results suggest that the co-inoculation mitigates atrazine-induced oxidative stress on soybean by accelerating atrazine removal from soil and phosphorus accumulation in leaves, enhancing the chlorophyll contents, and regulating plant transcriptome. It may be suggested that co-inoculation of atrazine-degrading bacteria and inorganic phosphorus-solubilizing bacteria can be used as a potential method to alleviate atrazine toxicity to the sensitive crops.