Rates Of Atrazine Research Articles

Higher biodegradation rate of atrazine by Paenarthrobacter sp. KN0901 with P-doped hydrochar: The important role of biofilm regulated by autoinducer-2 regulated quorum sensing during the degradation process

The presence of atrazine residue in runoff from agricultural areas poses a significant risk to the ecosystem. This study aimed to develop microorganism-material systems using the atrazine-degrading strain Paenarthrobacter sp. KN0901 and P-doped hydrochar to effectively remove atrazine residues from aquatic environments. The atrazine degradation rate increased by 22.6 % with the addition of P-doped hydrochar after three days of incubation at 15 °C. Autoinducer-2 activity increased from 100 % to 116.7 % with P-doped hydrochar addition, indicating improved quorum sensing compared to free microorganisms. The extracellular polymeric substance content was significantly higher in the PHC groups compared to the blank groups, suggesting enhanced biofilm formation. Quorum sensing was inhibited by the use of nitazoxanide and sodium nitroprusside, leading to decreased atrazine degradation. In contrast, the presence of glucose and S-adenosyl methionine enhanced the rate of atrazine degradation due to elevated quorum sensing. These results suggested that P-doped hydrochar enhanced strain KN0901′s ability to assemble, increasing quorum sensing and accelerating atrazine degradation. Additionally, P-doped hydrochar promoted atrazine degradation by strain KN0901 under various conditions by enhancing quorum sensing. This work offers a new perspective on developing and using bioremediation techniques to remediate atrazine-contaminated environments under diverse conditions.

Degradation of Three Herbicides and Effect on Bacterial Communities under Combined Pollution.

Pesticide residues in soil, especially multiple herbicide residues, cause a series of adverse effects on soil properties and microorganisms. In this work, the degradation of three herbicides and the effect on bacterial communities under combined pollution was investigated. The experimental results showed that the half-lives of acetochlor and prometryn significantly altered under combined exposure (5.02-11.17 d) as compared with those of individual exposure (4.70-6.87 d) in soil, suggesting that there was an antagonistic effect between the degradation of acetochlor and prometryn in soil. No remarkable variation in the degradation rate of atrazine with half-lives of 6.21-6.85 d was observed in different treatments, indicating that the degradation of atrazine was stable. 16S rRNA high-throughput sequencing results showed that the antagonistic effect of acetochlor and prometryn on the degradation rate under combined pollution was related to variation of the Sphingomonas and Nocardioide. Furthermore, the potential metabolic pathways of the three herbicides in soil were proposed and a new metabolite of acetochlor was preliminarily identified. The results of this work provide a guideline for the risk evaluation of combined pollution of the three herbicides with respect to their ecological effects in soil.

Acid-modified hydrochar for higher biodegradation rate of atrazine in various conditions by Paenarthrobacter sp. KN0901: Higher cell viability and bacterial number

Microbial remediation is a viable and eco-friendly approach for decontaminating pollution. However, its effectiveness can be limited by the microorganisms’ survival and growth in changing environments. Hydrochar materials have been utilized in this study to increase the growth and atrazine degradation capabilities of Paenarthrobacter sp. KN0901, a strain capable of atrazine biodegradation. Acid-modified hydrochars exhibited a higher carbonation rate, specific surface area, and number of defect sites compared to raw hydrochar. Following three days of incubation at 15 °C, the atrazine degradation rate increased from 90.7 % to 98.2 % when utilizing H3PO4-modified hydrochar (PHC). Additionally, the addition of PHC resulted in an increase in both bacterial concentration and cell viability of strain KN0901, by 1.6 and 1.4 times, respectively. Under various conditions, including temperatures of 4 ºC and 35 ºC, as well as pH levels of 5 and 9, and dd·H2O media, PHC exhibited a significant enhancement in atrazine degradation and cell viability of strain KN0901. Furthermore, PHC demonstrated the ability to sustain high proliferation and viability of strain KN0901 over five cycles, indicating its remarkable stability and biocompatibility. This study offers a new perspective on the development and application of bioremediation approaches in restoring atrazine-polluted environments, even under challenging conditions.

Biodegradation of atrazine and nicosulfuron by Streptomyces nigra LM01: Performance, degradative pathway, and possible genes involved

Microbial herbicide degradation is an efficient bioremediation method. In this study, a strain of Streptomyces nigra, LM01, which efficiently degrades atrazine and nicosulfuron, was isolated from a corn field using a direct isolation method. The degradation effects of the identified strain on two herbicides were investigated and optimized using an artificial neural network. The maximum degradation rates of S. nigra LM01 were 58.09 % and 42.97 % for atrazine and nicosulfuron, respectively. The degradation rate of atrazine in the soil reached 67.94 % when the concentration was 108 CFU/g after 5 d and was less effective than that of nicosulfuron. Whole genome sequencing of strain LM01 helped elucidate the possible degradation pathways of atrazine and nicosulfuron. The protein sequences of strain LM01 were aligned with the sequences of the degraded proteins of the two herbicides by using the National Center for Biotechnology Information platform. The sequence (GE005358, GE001556, GE004212, GE005218, GE004846, GE002487) with the highest query cover was retained and docked with the small-molecule ligands of the herbicides. The results revealed a binding energy of − 6.23 kcal/mol between GE005358 and the atrazine ligand and − 6.66 kcal/mol between GE002487 and the nicosulfuron ligand.

Confirmation of a four-way herbicide-resistant Palmer amaranth (Amaranthus palmeri) population in Iowa

Abstract Palmer amaranth (Amaranthus palmeri S. Watson) was first reported in Iowa in 2013 and has continued to spread across the state over the last decade. Importantly, A. palmeri is widely recognized as one of the more economically important weeds in production agriculture. The presence of A. palmeri in Iowa is concerning as the species has evolved resistance to nine herbicide sites of action, however, no formal characterization has been conducted on Iowa populations. Therefore, herbicide assays were conducted on an A. palmeri population collected in Harrison County, Iowa in 2023 (Southwest Palmer Amaranth, SWPA) and a known herbicide-susceptible population collected from Nebraska in 2001 (Palmer Amaranth Susceptible, PAS). The two populations were treated with preemergence and postemergence herbicides commonly used in Iowa. The treatments included preemergence applications of atrazine, metribuzin, and mesotrione and postemergence applications of atrazine, imazethapyr, glyphosate, lactofen, mesotrione, glufosinate, 2,4-D and dicamba at 1x and 4x the labeled rates. Survival frequency of SWPA was >90% when treated postemergence with 1x rates of imazethapyr, atrazine, glyphosate, and mesotrione compared to ≤6% for PAS. Both SWPA and PAS had 0% survival when treated with lactofen, glufosinate, 2,4-D, and dicamba at the 1x or 4x rates. Plant population density reduction for SWPA was 53% and 40% in response to 1x rates of preemergence-applied mesotrione and atrazine, respectively. Metribuzin applied preemergence reduced SWPA plant population density by >90% at both rates. Dose-response experiments revealed the 50% effective doses (ED50) of mesotrione, glyphosate, imazethapyr, and atrazine for SWPA were 9.5-,8.5-, 71- and 40-fold greater than for PAS, respectively. The results confirm that SWPA is four-way multiple herbicide-resistant. Amaranthus palmeri infestations are likely to continue to spread within Iowa, therefore diversified weed management programs that include early detection, rapid response, and effective multi-tactic management strategies will be required for control.

Effect of biochar on soil microbial community, dissipation and uptake of chlorpyrifos and atrazine

For the application of biochar in restoring pesticide-contaminated soils and minimizing the risk associated with their uptake in plants, it is crucial to understand the biochar impact on soil biological activities and dissipation and accumulation of pesticides in plant and soil systems. In this study, the effect of Mentha-distilled waste-derived biochar was investigated on chlorpyrifos and atrazine contaminated sandy loam soil. The four application rates of atrazine (2, 4, 6, and 8 mg kg−1) and chlorpyrifos (2, 4, 6, and 12 mg kg−1) and a single application rate of biochar (4%) were used in this study. The degradation of pesticides, the diversity of the bacterial community, and enzymatic activities (alkaline phosphatase, dehydrogenase, arylsulfatase, phenol oxidase, urease activity and N-acetyl glucosaminidase) were examined in soil. The uptake of two pesticides and their effect on growth and stress parameters were also investigated in plants (A. paniculata). The dissipation of chlorpyrifos and atrazine followed simple first-order kinetics with a half-life of 6.6–74.6 and 21–145 days, respectively. The presence of deisopropyl atrazine desethyl atrazine (metabolites of atrazine) and 3,5,6-trichloro-2-pyridinol (a metabolite of chlorpyrifos) was observed in soil and plant tissues. Biochar application significantly (p = 0.001) enhanced the degradation rate of chlorpyrifos and atrazine leading to the lower half-life of chlorpyrifos and atrazine in soil. A significant reduction (p = 0.001) in the uptake of chlorpyrifos and atrazine and alteration in their binding affinity and uptake rate in plant tissues was observed in biochar treatments. The incorporation of biochar improved chlorpyrifos/atrazine degrader and plant growth-promoting bacterial genera such as Balneimonas, Kaistobacter, Rubrobacter, Ammoniphilus, and Bacillus. The upregulation of functional genes associated with nucleotide, energy, carbohydrate, amino acid metabolism, xenobiotic biodegradation, and metabolism: atrazine degradation was observed in biochar treatments. The biochar amendments significantly (p = 0.001) reduced the plant’s uptake velocity (Vmax) and affinity (Km) of chlorpyrifos and atrazine. These results delineated that Mentha-distilled waste-derived biochar can potentially remediate chlorpyrifos and atrazine contaminated soils and ensure the safety of plants for consumption.Graphical

Confirmation of a five‐way herbicide‐resistant Amaranthus tuberculatus population in North Carolina

AbstractAmaranthus tuberculatus (waterhemp) is a pervasive weed of the Mid‐west and ‐south United States and is not native to North Carolina but infestations in crop fields have been reported recently. Amaranthus tuberculatus has evolved resistance to seven herbicide groups and multiple herbicide‐resistant populations are common where the species is native. The reported A. tuberculatus infestations in North Carolina have not been controlled with herbicides but no formal herbicide resistance characterisation has been conducted to date. Glasshouse dose–response experiments were conducted to determine the susceptibility of a population collected from Surry County, North Carolina to commonly applied postemergence herbicides compared to a herbicide‐susceptible population collected from Story County, Iowa. The Surry County population survived labelled rates of imazethapyr, atrazine, glyphosate, fomesafen, and mesotrione; the Story County population was controlled with these herbicides. Further, 2,4‐D, dicamba, and glufosinate effectively controlled the Surry and Story County populations. Molecular sequencing assays were subsequently conducted to determine if altered target sites facilitated resistance in the acetolactate synthase (ALS), 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS), photosystem II (psbA), and protoporphyrinogen oxidase (PPX2) genes. The Surry County population carried a Trp574Leu and ∆Gly210 mutations in the ALS and PPX2 gene, respectively. No mutations that would confer resistance were found in the EPSPS or psbA gene for either population. The results of both experiments provide evidence that a five‐way herbicide‐resistant A. tuberculatus population has encroached North Carolina. More research is needed to determine the mechanisms of resistance to atrazine, glyphosate, and mesotrione.

Experimental degradation of atrazine in soil by dielectric barrier discharge and optimization

In this study, a self-made rotating double-media barrier reactor was used for remediation of atrazine contaminated soil, aiming to provide a reference for industrial application of low-temperature plasma treatment of organic contaminated soil. The effects of applied voltage and reactor state on the reactor discharge performance were investigated. When the applied voltage was increased, the energy efficiency of low-temperature plasma increased; the effect of reactor state was not significant. The effects of input voltage, reactor rotational speed and soil water content on the degradation efficiency of atrazine were investigated, and the results showed that the degradation rate of atrazine increased when the input voltage was 35 kV and the treatment time was 25 min, and the degradation rate of atrazine was 71.12%; when the reactor rotational speed and soil water content were 18.7 r/min and 0.8%, the degradation rates were 73.25% and 65.41%. The response surface method was applied to optimize the selection. The results showed that the significance degree of each factor was input voltage > soil water content > rotating motor speed, and the optimal conditions were 0.6% soil water content, 37 kV input voltage, 18 r/min reactor speed, and 51.93% atrazine degradation rate.

Phylogenetic distance affects the artificial microbial consortia’s effectiveness and colonization during the bioremediation of polluted soil with Cr(VI) and atrazine

Soils co-contaminated with heavy metals and organic pollutants are common and threaten the natural environment and human health. Although artificial microbial consortia have advantages over single strains, the mechanism affecting their effectiveness and colonization in polluted soils still requires determination. Here, we constructed two kinds of artificial microbial consortia from the same or different phylogenetic groups and inoculated them into soil co-contaminated with Cr(VI) and atrazine to study the effects of phylogenetic distance on consortia effectiveness and colonization. The residual concentrations of pollutants demonstrated that the artificial microbial consortium from different phylogenetic groups achieved the highest removal rates of Cr(VI) and atrazine. The removal rate of 400 mg/kg atrazine was 100%, while that of 40 mg/kg Cr(VI) was 57.7%. High-throughput sequence analysis showed that the soil bacterial negative correlations, core genera, and potential metabolic interactions differed among treatments. Furthermore, artificial microbial consortia from different phylogenetic groups had better colonization and a more significant effect on the abundance of native core bacteria than consortia from the same phylogenetic group. Our study highlights the importance of phylogenetic distance on consortium effectiveness and colonization and offers insight into the bioremediation of combined pollutants.

Ultrathin g-C3N4 composite Bi2WO6 embedded in PVDF UF membrane with enhanced permeability, anti-fouling performance and durability for efficient removal of atrazine

A novel Bi2WO6-g-C3N4/polyvinylidene fluoride (PVDF) composite ultrafiltration (UF) membrane (BWO-CN/PVDF) was prepared by microwave hydrothermal and immersion precipitation phase transformation method. The BWO-CN/PVDF-0.10 exhibited an outstanding photocatalytic removal rate of atrazine (ATZ) (97.65 %) under the simulated sunlight and enhanced permeate flux (1356.09 L·m−2·h−1). The multiple optical and electrochemical detection confirmed that combining ultrathin g-C3N4 and Bi2WO6 can increase carrier separation rate and prolong its lifetime. The quenching test revealed that h+ and 1O2 were the prominent reactive species. Additionally, after a 10-cycle photocatalytic process, the BWO-CN/PVDF membrane presented remarkable reusability and durability. And it showed excellent anti-fouling performance by filtering BSA, HA, SA, and Songhua River under simulated solar irradiation. The molecular dynamic (MD) simulation showed that the combination of g-C3N4 and Bi2WO6 can enhance the interaction between BWO-CN and PVDF. This work opens up a new idea for designing and constructing a highly efficient photocatalytic membrane for water treatment.

Application of Modified Biochar in the Treatment of Pesticide Wastewater by Constructed Wetland

To explore the synergistic effects of modified biochar in the purification of herbicide-containing wastewater, the effect of biochar addition on the removal effect of the herbicide atrazine in wastewater was verified by the addition of biochar bags in a small reed bed-constructed wetland in the laboratory. The results showed that the addition of sulfuric acid-modified biochar could increase the removal rate of atrazine in wastewater from 50% to 70%, and the COD elimination rate in wastewater was from 66.7% to 86.7%. The addition of biochar to the constructed reed bed wetland improved the removal efficiency of total nitrogen and total phosphorus in the wastewater, and the outlet water from the constructed wetland reached the Class III level of China’s surface water quality standard (the inlet water was inferior to Class V). The experimental design met the requirements of low-cost, generalized atrazine-containing wastewater treatment and thus could have the potential for wide application. The results reflected the application potential of modified biochar as a synergist in the treatment of herbicide wastewater in constructed wetlands.

Catalytic Ozonation of Atrazine Enhanced by Mesoporous CeO2: Morphology, Performance and Intermediates

Heterogeneous catalytic ozonation is an alternative approach for the removal of refractory pollutants from water, and the fabrication of mesoporous materials with high dispersibility would enhance the catalytic efficiency. A mesoporous CeO2 was prepared by the nanocasting method with SBA-15 as a hard template, and was investigated in the catalytic ozonation of atrazine. The synthetical CeO2 nanorods have a specific surface area of 95.08 m2/g, a diameter of 10.16 nm, and a spacing of 2.18 nm. The removal rate of atrazine was 85.5%, 64.8%, and 46.4% in the order of catalytic ozonation by synthetical CeO2 > single ozonation > catalytic ozonation by commercial CeO2, respectively. The superior activity of the synthetical CeO2 could be attributed to the well-ordered mesoporous structure, the high surface area, and the redox Ce3+/Ce4+ cycling. Moreover, eight organic intermediates were identified after one minute of catalytic ozonation of atrazine, and the cleavage of the ethylamino group was proposed as the main pathway of atrazine degradation.

Triboelectric nanogenerator enhanced radical generation in a photoelectric catalysis system via pulsed direct-current

Traditional photoelectric catalysis technologies are limited by the needs for large external energy input. In this study, the self-powered photoelectric catalysis was established by a spherical triboelectric nanogenerator (S-TENG) under a pulsed direct-current electric field to improve the removal rate of Atrazine (ATZ). Also, the electrical output performance of S-TENG was tested. To further improve the utilization of light and degradation efficiency of ATZ, the photoelectrode (TiO2 nanotube) and photocatalyst (6HF-TiO2 nanosheets) were both used to degrade ATZ. The removal rate of ATZ was enhanced by 8.53%, and the mineralization was increased by 27.2% within 30 min in the photoelectric catalysis system with pulse direct-current electric field by S-TENG. The degradation mechanism of ATZ was also demonstrated by the EPR tests and free radicals quenching experiments. The result showed that the photogenerated free radicals were increased by triboelectric pulsed direct-current during the photoelectric catalysis degradation. The hydroxyl radical (•OH) played an essential role in the degradation of ATZ in the self-powered photoelectric catalysis system. In addition, the degradation pathway of ATZ was proposed in detail based on LC-MS/MS test and density functional theory (DFT) calculation. Furthermore, the toxicity of ATZ and its degradation intermediates were evaluated by the ECOSAR program. Overall, this research provides a novel strategy for enhancing the performance of self-powered photoelectric catalysis processes for wastewater treatment.

Terbuthylazine herbicide: an alternative to atrazine for weed control in glyphosate-tolerant maize

It is proposed that the herbicide terbuthylazine is more effective than atrazine in controlling weeds in maize. This study aimed to evaluate the efficacy of terbuthylazine and atrazine in a mixture with glyphosate in glyphosate-tolerant maize for post-emergence application. The experiment was conducted over three trials using randomized blocks with 4 repetitions and 10 treatments, composed by terbuthylazine rates + glyphosate, atrazine rates + glyphosate, [atrazine + mesotrione] + glyphosate, atrazine + tembotrione, isolated glyphosate, and nontreated control. Trial 1 were infested with Bidens subalternans DC. and Commelina benghalensis L; trial 2 with Urochloa plantaginea (Link) R. D. Webster, Ipomoea spp., volunteer soybean, B. subalternans, and grasses; and trial 3 infestation with C. benghalensis, U. plantaginea, Ipomoea spp., volunteer soybean, B. subalternans, Amaranthus hybridus L., and grasses. Weed control, crop injury, and yield were evaluated. Terbuthylazine + glyphosate showed an efficacy equivalent to that of atrazine or [atrazine + mesotrione] + glyphosate in the control of broadleaves and C. benghalensis. In contrast, the efficacy of terbuthylazine was similar or greater than that observed for atrazine in controlling grasses, depending on the location. Terbuthylazine is an important partner of glyphosate in controlling weeds in maize and is an alternative to atrazine.

Interaction between tolpyralate and atrazine for the control of annual weed species in corn

AbstractMany studies have documented the interaction between 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting and photosystem II (PSII)-inhibiting herbicides. Most have focused on the interaction between mesotrione and atrazine, with only a few studies characterizing the nature of the interaction between tolpyralate and atrazine. Therefore, five field experiments were conducted in Ontario, Canada, over a 3-yr period (2019 to 2021) to characterize the interaction between three rates of tolpyralate (15, 30, and 45 g ai ha−1) and three rates of atrazine (140, 280, and 560 g ai ha−1) for the control of seven annual weed species in corn (Zea mays L.). Tolpyralate at 30 or 45 g ha−1 applied with atrazine at 280 or 560 g ha−1 controlled velvetleaf (Abutilon theophrasti Medik.), redroot pigweed (Amaranthus retroflexus L.), common ragweed (Ambrosia artemisiifolia L.), common lambsquarters (Chenopodium album L.), and wild mustard (Sinapis arvensis L.) >90% at 8 wk after application (WAA). Tolpyralate and atrazine were synergistic at each rate combination for the control of A. theophrasti at 8 WAA. In contrast, A. retroflexus and S. arvensis control at 8 WAA was additive with each rate combination. At 8 WAA, C. album control was generally additive, but one rate combination was synergistic. Ambrosia artemisiifolia control at 8 WAA was synergistic with five rate combinations and additive with the other four. Barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] control at 8 WAA was additive with seven of the rate combinations and synergistic with two. Setaria spp. control at 8 WAA was synergistic with one more rate combination compared with E. crus-galli, but the two weed species shared the same synergistic rate combinations. This study concludes that extrapolation or broad classifications of the interaction between tolpyralate and atrazine would be inappropriate, as the interaction can vary due to herbicide rate, weed species, and the response parameter analyzed.

Self-cleaning ceramic membranes coated with low crystalline Fe2O3@CMWCNTs for highly efficient photo-Fenton removal of aromatic compounds

Nanomaterials coated ceramic membranes have become one of the most promising methods to degrade organic pollution. In this study, low crystalline metal nanomaterials were coated on ceramic membranes for the first time. This research fabricated a ceramic membrane with low crystalline Fe2O3@carboxylic multi-walled carbon nanotubes (CMWCNTs) and evaluated its aromatic compounds-degrading ability and self-cleaning ability. The coated membrane demonstrated an excellent removal rate (＞90%) of phenol and atrazine in 120 min’s continuous flow filtration via surface photo-Fenton reaction. Quenching experiments reveal the active substances of the reaction system were singlet oxygen (1O2) and a small amount of hydroxyl radical (·OH). With humic acid (HA) and bovine serum albumin (BSA) as model pollutants, the polluted membranes recovered 84.4% and 77.0% flux through the photo-Fenton reaction respectively, which proved the self-cleaning performance of the coated membrane. After 6 cycles, an average degradation efficiency of 92% for phenol was maintained in continuous flow filtration. These results indicated the efficacy of the photo-Fenton coupling coated membrane for treating organically polluted water and its relevance for the design and application of future photo-Fenton membrane filtration system.

Oxygen vacancies promoted heterogeneous catalytic ozonation of atrazine by defective 4A zeolite

The ozone activation reaction is becoming more popular with the treatment of organic pollutants, while the key to improving the efficiency heavily lies in the selection of active catalysts. In this study, we demonstrate that synthetic 4A zeolite with a high surface oxygen vacancy density and acidity exhibits excellent activity toward the ozonation process, where the removal rates of atrazine (ATZ) reached 87.5% at 6 min, and the removal rates of Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) reached 66.7% and 35.8% at 15 min, respectively. Compared with commercial 4A zeolite and synthetic 4A zeolite with acid treatment, the ozonation activities of 4A zeolites positively correlate with the surface acidity. Mechanistic investigations have identified that hydroxyl radicals are the main reactive oxygen species, and thus, the degradation pathway of ATZ is provided. Moreover, the influences of catalyst dosage, reaction temperature, pH and cycling stability on ozonation performance are systematically evaluated.

An ultrasound/O3 and UV/O3 process for atrazine manufacturing wastewater treatment: a multiple scale experimental study.

An ultraviolet (UV) and ultrasound (US) enhanced ozonation method were developed to investigate their efficiency on the removal of atrazine and chemical oxygen demand (COD) in authentic atrazine manufacturing wastewater. The bench-scale tests suggested a positive effect of UV and US on the degradation of atrazine within a limited energy range. The pilot-scale flow-through system was further tested by using response surface methodology. The results showed that O3 and its interaction with UV promoted the degradation of both COD and atrazine while its interaction with US inhibited the removal of COD but promoted the removal of atrazine. The optimal removal rate of atrazine (96.9%) was achieved in the condition of 6.86 W/L UV, 1.96 g/L·h O3 and 294 W/L US. Chloride ions hindered the atrazine degradation, but the generated free chlorine radicals were still able to react with atrazine. In terms of energy-effectiveness, the configuration of 14.7 W/L UV and 1.96 g/L·h O3 is the best option, which have the electrical energy per order of 181.6 kWh/m3 for atrazine and 0.13 kWh/g COD. These method and findings could be helpful in the development of energy-efficient advanced oxidation processes in treating wastewater with high salinity and COD loadings.

Efficient catalyst prepared from water treatment residuals and industrial glucose using hydrothermal treatment: Preparation, characterization and its catalytic performance for activating peroxymonosulfate to degrade imidacloprid

Water treatment residuals (WTRs), as by-products of drinking water treatment plant, were used as catalyst for persulfate activation to degrade organic pollutants. In this study, G-HWTRs were successfully prepared by hydrothermal treatment, which combined WTRs and a hydrothermal reducing agent (industrial glucose) in different ratios. These materials manifested upgraded performance compared with raw WTRs and HWTRs (prepared only with WTRs under hydrothermal condition) in imidacloprid (IMD) degradation. The elemental composition, structure, morphological and magnetic properties of the G-HWTRs were investigated. And the influences of peroxymonosulfate (PMS) concentration, G-HWTRs dosage, initial pH, water matrix on IMD degradation were determined. The results demonstrated that G-HWTRs-3 had the best catalytic performance, 10 μM IMD was almost completely degraded in the system of G-HWTRs (0.2 g L−1) and PMS (0.1 mM) within 2 h without pH adjustment. Based on the results of the electron spin-resonance spectroscopy (ESR) tests and radicals scavenging experiments, all of SO4−, OH, 1O2 and O2− were the reactive oxygen species driving the IMD degradation, and OH was regarded as the main role of IMD degradation. The possible degradation pathways of IMD were further proposed based on the degradation intermediates that identified by LC-MS. Besides, further experiments indicated G-HWTRs has degradation potential for various pollutants, the degradation rate of atrazine (ATZ), acetochlor (ACE) and simazine (SMX) within 2 h achieved 92.54%, 83.88% and 90.25%, respectively. These results confirmed G-HWTRs has good catalytic performance and activation potential on PMS, providing an effective method for remediating organic polluted wastewater.

A stable biochar supported S-nZVI to activate persulfate for effective dichlorination of atrazine

Sulfidation of nano-zero valent iron (nZVI) has attracted extensive attention because it can improve the reactivity of nZVI. Here, a type of catalyst, biochar supported sulfurized nZVI (S-nZVI@BC) was designed by a sample one-pot method, in which biochar was dispersed into Fe3+ solution under the flowing stream of N2 condition, subsequently, NaBH4 and Na2S2O4 solution were added dropwise at a constant speed. The as-prepared catalyst possessed obvious irregular shape and sulphur had been successfully doped. The most suitable ratio of sulphur to iron (S/Fe = 0.15) and the optimum dosages of S-nZVI@BC (0.1 g/L) and persulfate (PS, 1 mM) were determined. After three consecutive cycles, the removal rates of atrazine in the systems of nZVI-PS, S-nZVI-PS and S-nZVI@BC-PS maintained at 55.5%, 87.1% and 96.8%, respectively, implying that the stability of nZVI was enhanced by S doping and BC support. In addition, the S-nZVI@BC could keep good activity in a wide pH range of 2.86–10.53, and could effectively reduce the activation energy of reaction. And the catalyst retained relatively good catalytic performance in actual natural water. The identification of active substances was achieved by electron spin resonance test, including •OH and SO4•−, 1O2 and PFRs. According to the law of Cl− conservation, the Cl element in atrazine molecule was completely removed. This study could provide an effective catalyst preparation method to promote PS activation for degradation of organic pollutants.