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Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO(2) as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions...
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... while C-P lyase cleaves the C-P bond, yielding benign phosphate and sarcosine [23][24][25][26] . AMPA exhibits similar toxicity and a longer half-life than GP, interferes with DNA synthesis and repair in fish and amphibians, and can have adverse effects on human blood cells [24][25][26][27][28] , making the C-P lyase pathway more desirable 21,[29][30][31] . ...
... while C-P lyase cleaves the C-P bond, yielding benign phosphate and sarcosine [23][24][25][26] . AMPA exhibits similar toxicity and a longer half-life than GP, interferes with DNA synthesis and repair in fish and amphibians, and can have adverse effects on human blood cells [24][25][26][27][28] , making the C-P lyase pathway more desirable 21,[29][30][31] . Bacterial and fungal species have been studied for biodegradation of GP in water 21,32 , however, the performance of microorganisms for GP remotion depends on factors such as pH, temperature, and GP concentration, as well as on deficits of available nitrogen and phosphorus, which are not typical in natural environments 30 . ...
... Oxidative processes for GP remotion include photo-Fenton and electro-Fenton oxidation, photolysis using hydrogen peroxide or ozone in combination with UV light, electrochemical oxidation, and photocatalysis 24,[39][40][41][42][43][44][45][46][47][48] . However, the majority of these strategies result in the formation of toxic AMPA. ...
Here, four MOFs, namely Sc-TBAPy, Al-TBAPy, Y-TBAPy, and Fe-TBAPy (TBAPy: 1,3,6,8-tetrakis(p-benzoic acid)pyrene), were characterized and evaluated for their ability to remediate glyphosate (GP) from water. Among these materials, Sc-TBAPy demonstrates superior performance in both the adsorption and degradation of GP. Upon light irradiation for 5 min, Sc-TBAPy completely degrades 100% of GP in a 1.5 mM aqueous solution. Femtosecond transient absorption spectroscopy reveals that Sc-TBAPy exhibits enhanced charge transfer character compared to the other MOFs, as well as suppressed formation of emissive excimers that could impede photocatalysis. This finding was further supported by hydrogen evolution half-reaction (HER) experiments, which demonstrated Sc-TBAPy’s superior catalytic activity for water splitting. In addition to its faster adsorption and more efficient photodegradation of GP, Sc-TBAPy also followed a selective pathway towards the oxidation of GP, avoiding the formation of toxic aminomethylphosphonic acid observed with the other M³⁺-TBAPy MOFs. To investigate the selectivity observed with Sc-TBAPy, electron spin resonance, depleted oxygen conditions, and solvent exchange with D2O were employed to elucidate the role of different reactive oxygen species on GP photodegradation. The findings indicate that singlet oxygen (¹O2) plays a critical role in the selective photodegradation pathway achieved by Sc-TBAPy.
... Prepared by the authors. Direct photolysis is not considered an option in most studies in the literature because it has a low efficiency for most pesticides (Assalin et al., 2010). Therefore, the low efficiency obtained in the photolysis of glyphosate was expected, showing that it is necessary to use other compounds to assist in this degradation, such as the catalyst titanium dioxide and ozone. ...
... The determination of the degree of degradation of pesticides using ozonation with advanced oxidative processes is very difficult due to the complexity of the reactions. The complete disappearance of the compound monitored with liquid chromatography is not enough 8 to prove the disinfection of the solution, since other more toxic compounds may be present or were produced by the treatment (Assalin et al. 2010). Thus, the reason why the concentration of glyphosate increased can be justified by the formation and/or presence of AMPA and other compounds in the glyphosate solution in the ozonation process since these compounds influence the absorbance of light by the spectrophotometer. ...
Objective: The purpose of this study was to assess the efficiency of an advanced oxidative process gradually applying different oxidative agents, i. e. UV, TiO2 and O3, to evaluate the removal efficiency of a commercial composition of glyphosate from an aqueous matrix. Theoretical framework: In Brazil, approximately 150 million liters of glyphosate are consumed per year, representing 30% of the total pesticides used, which can contaminate surface water due to aerial or terrestrial spraying, erosion and runoff, improper disposal of commercial packaging and cleaning of contaminated spray tanks. Advanced oxidative processes have emerged as an alternative to the degradation of glyphosate since they have high efficiency in reducing organic contaminants to an acceptable limit with a low operating cost. Method: Experimental consisted of a benchtop-scale system, composed of a batch reactor with a 25W UV lamp inside and a feeding pump in a recirculation reservoir. It was responsible for performing the removal of glyphosate by means of an advanced oxidative process after receiving TiO2 and O3 application. Results and conclusion: The photolysis process obtained an efficiency of 24.69%, the photocatalytic oxidation process with TiO2 obtained 37.78%, and the photocatalytic ozonation with TiO2 obtained 45.46% efficiency in 60 minutes of reaction. The possible formation of byproducts after one hour of reaction due to the increase in concentration was also observed, since it was not possible to distinguish glyphosate from other compounds in the analysis method applied. Implications of the research: As demonstrated by the results of the experimental assays, the advanced oxidative technique proved to be very efficient to make the removal of a commercial composition of glyphosate from an aqueous matrix. Originality/value: It has been shown that it is possible to remove glyphosate in an efficient way, using a highly efficient fast technique.
... Furthermore, a degradation route was proposed in which oxidant species can cleave the C-P link to generate phosphate, and subsequently glycine with the final products being formic acid, ammonium, nitrate, formaldehyde, and phosphate ions, without AMPA and sarcosine as intermediate products. Assalin et al. (2010) confirmed the presence of a TiO 2 photocatalysis efficiently removed GLY and its breakdown mediators; 92% of total organic carbon was removed from an acid GLY solution (pH = 10) after being treated for 30 min. At an initial concentration of 0.25 mmolL − 1 and of 6.0 g L -1 of TiO 2 , S. Chen & Liu (2007) were able to degrade 92% of GLY after 3.5 h of irradiation. ...
... H 2 O 2 is added to the reaction system to stimulate the breakdown of ozone and aid production of OH radicals (Hoigné, 1998). Also, the ozonation efficiency can be enhanced by the increasing the pH of the system which stimulates steady generation of OH radicals (Assalin et al., 2010). Ozonation for GLY removal can occur by either direct oxidation by ozone or indirect oxidation by hydroxyl radicals which then attack and decompose GLY (Andreozzi et al., 1999). ...
... Ozonation for GLY removal can occur by either direct oxidation by ozone or indirect oxidation by hydroxyl radicals which then attack and decompose GLY (Andreozzi et al., 1999). The oxidation process via ozonation has resulted in the complete breakdown of GLY, which has been confirmed by various studies (Assalin et al., 2010). Using O 3 and H 2 O 2 together, GLY removal was achieved at a high efficiency (99%) and AMPA with a high percentage (85%) in a very short amount of time (Jönsson et al., 2013). ...
Glyphosate (GLY) also known as N-(phosphomethyl)-glycine and its commercially formulated contemporaries are the most widely used class of herbicides in the world. Due to the hydrophilic nature of this contaminant, it has been detected in surface water, effluents, groundwater, and agri-food items especially those that are in proximity to active agricultural zones. Although glyphosate was regarded to be less toxic to human and aquatic health, its metabolite such as aminomethylphosphonic acid (AMPA) is reported to be highly deleterious to the aquatic ecosystem and human health when exposed to it. Hence, this necessitates the development of sensitive and selective instrumental techniques to screen, detect and quantify this contaminant including their removal strategies from the environment. In view of this, the ecotoxicological impact of GLY and its metabolites (AMPA) on human and aquatic health and the various advanced instrumental techniques utilized for offsite e.g., chromatographic in tandem with mass spectrometry techniques (GC/MS,HPLC- MS,UPLC- MS/MS) and onsite (spectroscopic techniques, electrochemical techniques, and biosensors) analysis of this contaminant are comprehensively discussed. Furthermore, various treatment approaches such as adsorption, biological treatments and advanced oxidative processes utilized for the degradation and mineralization of GLY and its metabolites in environmental samples are well described. Finally, various challenges relating to glyphosate degradation were identified and suggestions were provided on possible ways of optimizing the recognized methods reported in published literature
... 39,40 Thus, TiO 2 is an active photocatalyst that can drive the oxidation of organic molecules, and hydrogen production, 41 utilizing reactive oxygen species (ROS) such as singlet oxygen ( 1 O 2 ), 42 hydrogen peroxide (H 2 O 2 ), ozone (O 3 ), and hydroxyl radicals (OH • ) as the driving forces for the advanced oxidation process (AOP). 30,43 However, these approaches often result in incomplete oxidative breakdown of PMG or lead to the formation of AMPA as one of the degradation products, which is not environmentally favorable. ...
Consumption of contaminated water can have detrimental effects on the health of every living organism on earth. There is, thus, a need to develop novel materials and technologies to purify water. Water is also a source of hydrogen, a clean renewable fuel that can be generated through the action of a photoactive catalyst and the earth's abundant solar energy. Using photocatalysis, we can purify water by removing organic pollutants through the photodegradation reaction (oxidation) and produce hydrogen (H 2) through the hydrogen evolution reaction (reduction). However, we can combine these two reactions in a single process to achieve an efficient photocatalytic system. Herein, we report the dual-functional photocatalysis (DFP) on herbicide-contaminated water using TiO 2 polymorphs derived from the amino-functionalized metal−organic framework (MOF), MIL-125-NH 2. Heteroatom TiO 2 doping led to the generation of N-and N,S-doped TiO 2. Of all the pristine and doped TiO 2 phases synthesized, the N,S-doped anatase (NSTA) was the best dual-functional photocatalyst in degrading glyphosate (PMG) with simultaneous H 2 production at a rate of 660 μmol g −1 h −1. Nuclear Magnetic Resonance studies indicate the preferential cleaving of PMG's C−N bonds, here referred to as α and β C−N bonds, leading to the formation of glycine, formic acid, and phosphoric acid as the major degradation products. Density functional theory calculations indicate PMG's activation through the carboxy and phosphoric acid groups on the surface of NSTA and through the phosphoric acid group on the surface of TiO 2-rutile. Our results suggest that the catalytic activity of NSTA can be attributed to the templated impact of the parent MOF, owing to its porosity, redshifting of the band absorption edge toward the visible region, reduced energy bandgap, surface defects, and the presence of oxygen vacancies. The binding mode of PMG to NSTA and its degradation allowed us to test the photodegradation of other herbicides, such as glufosinate ammonium and 2,4-dichlorophenoxyacetic acid. Interestingly, our MOF-derived NSTA proved to be active in purifying water when all three herbicides were combined and produced H 2 with a rate of 329 μmol g −1 h −1 simultaneously.
... Main AOPs include ultraviolet (UV) irradiation, H2O2/UV, photocatalysis, ozonation, electrochemical oxidation, Fenton processes, and Fenton-like processes. Many of these have been used to remove GLY from wastewater [20][21][22][23][24][25]. ...
Glyphosate is a widely used herbicide, and it is an important environmental pollutant that can have adverse effects on human health. Therefore, remediation and reclamation of contaminated streams and aqueous environments polluted by glyphosate is currently a worldwide priority. Here, we show that the heterogeneous nZVI–Fenton process (nZVI + H2O2; nZVI: nanoscale zero-valent iron) can achieve the effective removal of glyphosate under different operational conditions. Removal of glyphosate can also take place in the presence of excess nZVI, without H2O2, but the high amount of nZVI needed to remove glyphosate from water matrices on its own would make the process very costly. Glyphosate removal via nZVI–-Fenton was investigated in the pH range of 3–6, with different H2O2 concentrations and nZVI loadings. We observed significant removal of glyphosate at pH values of 3 and 4; however, due to a loss in efficiency of Fenton systems with increasing pH values, glyphosate removal was no longer effective at pH values of 5 or 6. Glyphosate removal also occurred at pH values of 3 and 4 in tap water, despite the occurrence of several potentially interfering inorganic ions. Relatively low reagent costs, a limited increase in water conductivity (mostly due to pH adjustments before and after treatment), and low iron leaching make nZVI–Fenton treatment at pH 4 a promising technique for eliminating glyphosate from environmental aqueous matrices.
... Various techniques, such as adsorption on solid substrates, biological degradation, advanced oxidation processes (AOPs), and photocatalysis, have been investigated for the mitigation of glyphosate contamination [17,21]. However, the widespread application of many of these techniques is limited because of the lack of stability under environmental conditions and the need for post-adsorption treatment [22,23]. ...
Glyphosate, the most widely used herbicide, has been linked to adverse effects on human health and non-target species. We report a highly efficient light-activated catalytic mineralization of glyphosate by [email protected]4/BiOBr dual heterojunction photocatalyst. Rapid degradation of glyphosate by [email protected]4/BiOBr was achieved within 5 min of the reaction. The palladium decoration of BiVO4/BiOBr nanocomposite enhanced the degradation four times. The glyphosate photocatalytic mineralization pathway was investigated via the determination of the degradation products. [email protected]4/BiOBr photocatalyst displayed high stability after six glyphosate degradation cycles. Such results pave the way for sustainable catalytic technologies to minimize the global impact of pesticides.
... Several technologies are developed and applied to promote the removal of ECs from water resources, such as membrane separation methods [8], electrolysis [9], photocatalytic degradation [10], advanced oxidative processes [11], microwave radiation [12], ozonation [13], and ultraviolet irradiation [6]. However, most of these remediation technologies have limited flexibility, high cost, low efficiency, and possible production of secondary pollutants [14]. ...
The present work used a statistical physics approach to present new insights into the adsorption of the pesticide glyphosate on modified carbon nanotubes via green synthesis (MWCNT/MPNs-Fe). The experimental equilibrium curves obtained for this system under pH 4 at temperatures 298, 308, 318, and 328 K were simulated from monolayer, double layer, and multilayer models, with 1 and 2 energies, considering real and ideal fluid approaches. Taking into account the statistical indicators and the physical meaning of the parameters, exploring simplifying hypotheses, the Hill model with 1 energy and ideal fluid approach (M1) presented the best prediction of the experimental data, indicating that glyphosate adsorption occurs by the formation of a monolayer and that pesticide interaction with MWCNT/MPNs-Fe are characterized by only one energy. Based on this approach, to assess the steric aspects of the system, the number of molecules adsorbed per site (n), the density of receptor sites (Nm), adsorption capacity at saturation (Qsat), and concentration at half-saturation (W) were interpreted. As for the energetic aspects, the adsorption energy (ΔE) was inferred. The combination of parameters to its evolution with temperature and the magnitude of ΔE indicated an exothermic process involving a physical interaction mechanism. Finally, the new insights showed that the MWCNT/MPNs-Fe adsorbent favored pesticide adsorption by interacting glyphosate molecules with the metallic iron nanoparticles present on the adsorbent surface.
... Notwithstanding, even though many applications have been received, it needs to be removed in a sustainable way, namely adsorption, photo-catalytic degradation, composite organic oxidation, photo-Fenton, improved oxidation process, gaseous degradation, nanofiltration (including membranes), ozonation, coagulation, liquid extraction, and solid-phase extraction. By comparison, adsorption is more sophisticated than other methods [10][11][12][13][14]. ...
... Each test was examined in triplicate under the same experimental conditions, and each average values were recorded. Adsorption influencing parameters were examined through batch method, such as initial pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), initial concentration (5-50 mg/L), contact time (20-120 min), Fe@GNS-AC doses (0.01-2.0 g), and adsorbate-adsorbent interaction temperature (303-353 K) [29]. All experiments were studied by 350 rpm using thermostatic magnetic stirrer (TARSON-SPINOT™). ...
Groundnut shell is an agricultural waste material that was employed in the pyrolysis process to produce activated carbon using ferric chloride activation (Fe@GNS-AC) (T = 500–700 °C; N2 = 120 cm³/min). Fe@GNS-AC was conducted to remove glyphosate from aqueous solution through batch adsorption technique. The physiochemical properties of adsorbent was investigated following methods such as BETsurface, X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), Boehm’s titration, Point zero charge (pHZPC), total pore volume, and Fourier transform infrared spectroscopy (FT-IR). The maximum glyphosate adsorption capacity of 267.91 mg.g⁻¹ was achieved by the remaining parameters, namely, pH 4.6, initial adsorbate concentration (30 mg/L), contact time (60 min), and adsorbent dose (0.5 g). The equilibrium was ascribed using Langmuir, Freundlich, and Sips isotherms, where Sips and Freundlich model fits better (R² > 0.9) to equilibrium data. The kinetics models were well described with the pseudo-second-order kinetic and film diffusion mechanisms (R² > 0.9). The thermodynamic parameter for adsorption was exothermic and spontaneous in chemisorption mechanism (ΔH = − 29.416 kJ/mol; ΔG = − 13.838 to − 10.345 kJ/mol, T = 303-353 K). The DFT calculation was employed to understand the density of state (DOS), electrophilicity index (ω), chemical potential (μ), and chemical hardness (η) of the surface complexion in fermi level, and the mechanism suggested that chemisorption phenomenon is dominated by electronic interferences with Mullikan atomic charge transfer. Finally, exhausted adsorbent was examined by desorption mechanism and sodium chloride performed high eluting agent at fourth time cyclic process (80.39%). This study provides information Fe@GNS-AC synthesis, and removal of glyphosate. It may also benefit the separation of agricultural water or industrial wastewater treatment.
... In this technology, two mechanisms of glyphosate oxidation are used: direct oxidation by ozone (O 3 ) or indirect oxidation by hydroxyl radicals [108]. Through this process, complete degradation of glyphosate by ozonation has also been achieved [134]. In addition, high glyphosate and AMPA removal efficiencies have been reported when using O 3 and H 2 O 2 simultaneously, in a short reaction time [135]. ...
Glyphosate is a broad-spectrum herbicide extensively used worldwide to eliminate weeds in agricultural areas. Since its market introduction in the 70's, the levels of glyphosate agricultural use have increased, mainly due to the introduction of glyphosate-resistant transgenic crops in the 90's. Glyphosate presence in the environment causes pollution, and recent findings have proposed that glyphosate exposure causes adverse effects in different organisms, including humans. In 2015, glyphosate was classified as a probable carcinogen chemical, and several other human health effects have been documented since. Environmental pollution and human health threats derived from glyphosate intensive use require the development of alternatives for its elimination and proper treatment. Bioremediation has been proposed as a suitable alternative for the treatment of glyphosate-related pollution, and several microorganisms have great potential for the biodegradation of this herbicide. The present review highlights the environmental and human health impacts related to glyphosate pollution, the proposed alternatives for its elimination through physicochemical and biological approaches, and recent studies related to glyphosate biodegradation by bacteria and fungi are also reviewed. Microbial remediation strategies have great potential for glyphosate elimination, however, additional studies are needed to characterize the mechanisms employed by the microorganisms to counteract the adverse effects generated by the glyphosate exposure.
... There is a plethora of organic compounds in the troposphere, and glyphosate is one of them. 7,8 Glyphosate of chemical name N-(phosphonomethyl) glycine with chemical formula (OH) 2 -PO-CH 2 -NH-CH 2 -COOH is shorten as GPS. It is an organophosphate, non-selective, broad-spectrum, agrochemical herbicide that is used to kill or suppress growth of grasses, forbs, vines, shrubs, and trees by inhibiting the synthesis of aromatic amino acids necessary for protein formation in susceptible plants. ...
... It is an organophosphate, non-selective, broad-spectrum, agrochemical herbicide that is used to kill or suppress growth of grasses, forbs, vines, shrubs, and trees by inhibiting the synthesis of aromatic amino acids necessary for protein formation in susceptible plants. [7][8][9] GPS is a colourless, odourless crystalline powder, and the most widely and intensively used herbicide across the world. 7,8 The vapour pressure for GPS is very low, hence it is non-existent in atmosphere through volatilization 10 as we would expect for other volatile organic compounds. ...
... [7][8][9] GPS is a colourless, odourless crystalline powder, and the most widely and intensively used herbicide across the world. 7,8 The vapour pressure for GPS is very low, hence it is non-existent in atmosphere through volatilization 10 as we would expect for other volatile organic compounds. Despite this, recent works conducted in agricultural areas show that GPS is observed in over 60% of air and rain samples with concentrations ranging from 0.01 to 9.1 ng m À3 in air samples and from 0.1 to 2.5 mg L À1 in rainwater samples. ...
The rate constant of the reactions of cOH radicals with glyphosate (GPS) and its hydrates (GPS(H 2 O) n¼1-3) were evaluated using the dual method M06-2X/6-311++G(df,p)//6-31+G(df,p) over the temperature range of 200-400 K. The results served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP). The calculations yielded an atmospheric lifetime of 2.34 hours and a POCP of 24.7 for GPS. Upon addition of water molecules, there is an increase of lifetime and decrease of POCP for water monomer and water dimer. The POCP for water trimer is slightly above the gaseous GPS. However, the POCPs of GPS and its hydrates are comparable to that of alkanes. The GPS and its hydrates were found to be a potential reservoir of CO 2. The acidification potential (AP) of GPS was found to be 0.189 and decreases upon addition of water molecules. This shows negligible contribution to rain acidification as the AP is less than that of SO 2. The UV-vis spectra were attained using the M06-L/6-311++G(3df,3pd) method and cover the range 160-260 nm which fits well with experiment.
