Removal Of Paraquat Research Articles

Adsorption isotherm and kinetics of paraquat removal using activated carbon/iron oxide composite material

A composite material between activated carbon (AC) and iron oxide in nanoscale was used to remove paraquat from contaminated water. The surface area of AC/iron oxide nanoparticles was in the range of 754.39 to 775.81 m²/g for the ratio 1:1 to 10:1 AC:iron oxide nanoparticles. The maximum adsorption capacity was found at pH 11. Adsorption of paraquat increases with increase in temperature indicating an endothermic process. Sorption behaviour of paraquat onto AC/iron oxide nanoparticles was evaluated using the Langmuir and Freundlich isotherm. The adsorption behaviour of paraquat was well described by Freundlich isotherm indicated that AC/iron oxide nanoparticles posed heterogeneous surface with heterolayer paraquat coverage on the surface of composite material. First and second order kinetic models were tested. The paraquat adsorption rate fits a pseudo-second-order kinetic model where the rate-limiting step is assumed to be chemical sorption between the adsorbate and adsorbent. The AC/iron oxide nanoparticles can readily be separated from the solution using a permanent magnet.

Removal of Paraquat from Aqueous Solutions Using Multi-Walled Carbon Nanotubes: Kinetic, Isotherm and Thermodynamic Studies

Multi-walled carbon nanotubes (MWCNT) were used as an efficient adsorbent to remove Paraquat (PQ) molecules from its aqueous solutions. The initial PQ concentration, adsorption time and temperature had considerable effect on the removal of PQ onto MWCNT. The adsorption of PQ onto MWCNT followed the pseudo second-order kinetic model involving the particle-diffusion mechanism. The adsorption isotherms were fitted by the Langmuir isotherm, with the maximum adsorption capacity based on the former of 79.365 mg·g-1. Thermodynamic parameters, including Gibbs free energy changes (ΔG0), as well as changes in enthalpy (ΔH0) and entropy (ΔS0), were also calculated. The results demonstrated that PQ was adsorbed onto MWCNT spontaneously and endothermically in nature.

MDR1 transporter protects against paraquat-induced toxicity in human and mouse proximal tubule cells.

Paraquat is a herbicide that is highly toxic to the lungs and kidneys following acute exposures. Prior studies have demonstrated that the organic cation transporter 2 and multidrug and toxin extrusion protein 1 contribute to the urinary secretion of paraquat in the kidneys. The purpose of this study was to determine whether the multidrug resistance protein 1 (MDR1/Mdr1, ABCB1, or P-glycoprotein) also participates in the removal of paraquat from the kidneys and protects against renal injury. Paraquat transport and toxicity were quantified in human renal proximal tubule epithelial cells (RPTEC) that endogenously express MDR1, HEK293 cells overexpressing MDR1, and Mdr1a/1b knockout mice. In RPTEC cells, reduction of MDR1 activity using the antagonist PSC833 or siRNA transfection increased the cellular accumulation of paraquat by 50%. Reduced efflux of paraquat corresponded with enhanced cytotoxicity in PSC833-treated cells. Likewise, stable overexpression of the human MDR1 gene in HEK293 cells reduced intracellular levels of paraquat by 50%. In vivo studies assessed the renal accumulation and subsequent nephrotoxicity of paraquat (10 or 30 mg/kg ip) in wild-type and Mdr1a/1b knockout mice. At 4 h after paraquat treatment, renal concentrations of paraquat in the kidneys of Mdr1a/1b knockout mice were 750% higher than wild-type mice. By 72 h, paraquat-treated Mdr1a/1b knockout mice had more extensive tubular degeneration and significantly greater mRNA expression of kidney injury-responsive genes, including kidney injury molecule-1, lipocalin-2, and NAD(P)H quinone oxidoreductase 1, compared with wild-type mice. In conclusion, MDR1/Mdr1 participates in the elimination of paraquat from the kidneys and protects against subsequent toxicity.

Removal of paraquat from drinking water by activated carbon prepared from waste wood

In this study, activated carbon was produced from the chips of two wood species, namely Ayous (Triplochiton schleroxylon) and Sapelli (Entandrophragma cylindricum) and characterized for its texture by scanning electron microscopy, granulometry using a master sizer, and the structure by determining the iodine and methylene blue indices. The obtained carbon was used to study the adsorption of paraquat in aqueous solution. Results from the characterization of carbon revealed that it consist essentially of micropores and mesopores, a tubular structure, and a fine coating of very small granules on the surface (Ayous) and elongated fibers (Sapelli). The adsorption kinetics of paraquat in solution followed a maximum exponential growth model with three stages: the first, which corresponds to an increase adsorption of the molecule on sites located on the outer surface of the carbon, the second phase, which correspond to the diffusion of the molecules on the internal pores, and the third constant phase corresponding to the adsorption equilibrium. The equilibrium time obtained was 10 min for Ayous with 87% of paraquat adsorbed and 20min for Sapelli with 90% of paraquat adsorbed. The biosorption kinetics of paraquat in the solution followed a pseudo-first order and intra-particle diffusion model. Result from the influence of paraquat concentration and mass of carbon showed that, an increase in concentration and mass of the adsorbent impel respectively in the amount of the paraquat molecule adsorbed. Change of solution pH does not affect the amount of paraquat adsorbed whatever the type of carbon. The adsorbed amounts of paraquat decreased (from 88 to 60 mg g−1) as the ionic strength increased from 5 × 10−3 to 5 × 10−2 M. This study shows that activated carbon products obtained from Sapelli and Ayous wood chips, which are wastes released into the environment, can be used as low-cost biosorbents for the removal of organic micropollutants in drinking water.

Removal of paraquat from water by an Algerian bentonite

Abstract The sorption–desorption of the cationic pesticide 1,1′-dimethyl-4,4′-bipyridinium dichloride (paraquat) on a bentonite from Maghnia (Algeria) desiccated at 110 °C (M), and calcined at 400 °C (M400) and 600 °C (M600) from aqueous solution at 25 °C has been studied using batch experiments. A complete characterization of the natural and heat activated bentonite samples has been carried out through the following techniques: X-ray fluorescence spectroscopy, FTIR, X-ray diffraction, thermogravimetric and differential thermogravimetric analysis and surface analysis. In order to have a better understanding of the variables affecting the sorption of this herbicide, factors such as the working temperature or the ionic strength of the solution have been investigated. The sorption experimental data have been fitted to the Langmuir equation in order to calculate the maximum sorption capacities (X m ) of the samples. The results show that the sorption capacity of the calcined samples greatly decreased with heat treatment. On the other hand, the sorption process is hardly affected by the working temperature, whereas the higher electrolyte concentration, the lower sorption of this pesticide. In addition to batch experiments, a decontamination continuous process (DCP) was designed by the authors using the natural clay to evaluate the potential application of this adsorbent for removing paraquat from water.

Adsorption kinetics of herbicide paraquat in aqueous solution onto a low-cost adsorbent, swine-manure-derived biochar

Biochars have received increasing attention in recent years because of their significant properties such as carbon sequestration, soil fertility, and contaminant immobilization. In this work, the adsorptive removal of paraquat (1,1 0 -dimethyl-4,4 0 -dipyridinium chloride, one of the most widely used herbicides) from aqueous solution onto the swine-manure-derived biochar has been studied at 25 C in a batch adsorption system. The adsorption rate has been investigated under the controlled process parameters including initial pH (i.e., 4.5, 6.0, 7.5, and 9.0), paraquat concentration (i.e., 0.5, 1.0, 2.0, 4.0, and 6.0 mg/L), and biochar dosage (i.e., 0.10, 0.15, 0.20, 0.25, and 0.30 g/L). Based on the adsorption affinity between cationic paraquat and carbon-like adsorbent, a pseudo-second order model has been developed using experimental data to predict the adsorption kinetic constant and equilibrium adsorption capacity. The results showed that the adsorption process could be satisfactorily described with the reaction model and were reasonably explained by assuming an adsorption mechanism in the ion exchange process. Overall, the results from this study demonstrated that the biomass- derived char can be used as a low-cost adsorbent for the removal of environmental cationic organic pollutants from the water environment.

Paraquat removal from water by oxidation with Fenton's reagent

Fenton's reaction, an advanced oxidation process (AOP), was studied for paraquat degradation purposes. A parametric study was conducted and the variables considered were the temperature, the pH and the initial iron, hydrogen peroxide and paraquat concentrations, the latter in the range 50–200 mg/L. Under the optimum conditions ( T = 30.0 °C, [Fe 2+] 0 = 5.0 × 10 −4 M, [H 2O 2] 0 = 1.6 × 10 −2 M, and pH 0 = 3.0, for [PQ] 0 = 100 mg/L), complete paraquat degradation and about 40% of mineralization were reached after 4 h of reaction (batch reactor). Gramoxone commercial product revealed a slower initial rate of degradation than the paraquat analytical standard, probably due to the parallel consumption of the hydroxyl radicals by other organic compounds. A semi-empirical kinetic model was proposed to simulate the paraquat dichloride concentration histories under a wide range of conditions; the adequacy of the model was statistically checked and also validated by comparison with some additional experiments. The biodegradability and toxicity of the final oxidation products were assessed.

Study of the removal of paraquat from aqueous solution by biosorption onto Ayous ( Triplochiton schleroxylon) sawdust

This study concerns the batch biosorption of paraquat on Ayous ( Triplochiton schleroxylon) sawdust; the study centers on the evolution of biosorption parameters during the process. It appears that paraquat forms a monolayer on the sawdust surface as evidenced by the good correlation between the experimental data and the Langmuir model. The biosorption which is rather fast (the equilibrium was reached after ten minutes) follows a pseudo-second-order kinetic model and does not obey to the intra-particle diffusion model. According to the mathematical kinetic modeling, pore and surface mass transfer well describe the phenomenon. NaCl reduces the adsorption capacity of the material but has no significant effect on the kinetics. Alkaline solutions enhance the accumulation of the pollutant, the reverse being observed for acidic media. According to the thermodynamic data, this biosorption is a spontaneous and exothermic process. From these results we concluded that the adsorption of the pollutant is mainly due to cation exchange as indicated by the adsorption energy determined by the Dubinin–Radushkevich model ( E = 12.0736 kJ mol −1); some other interactions resulting from the affinity through organophilic interactions between paraquat and sawdust have also been pointed out. Desorption experiments conducted in HCl and HNO 3 solutions confirmed the proposed mechanism.

Removal of paraquat pesticide from aqueous solutions using a novel adsorbent material based on polyacrylamide and methylcellulose hydrogels

AbstractThis research studied the characteristics of poly(acrylamide) and methylcellulose (PAAm‐MC) hydrogels as a novel adsorbent material for removal of pesticide paraquat, from aqueous solution, with potential applications in curbing environmental risk from such herbicides. PAAm‐MC hydrogels with different acrylamide (AAm) and MC concentrations were prepared by a free‐radical polymerization method. The capability of the hydrogels in removing paraquat dichloride from aqueous solution was determined using UV–Vis analysis. The scanning electron microscopy method was used to study the morphological properties of the hydrogels, and swelling degree (Q) of the hydrogels was also measured. The entrapped MC in PAAm chains provoked significant changes in morphological, hydrophilic, and adsorption properties of the PAAm‐MC hydrogels. The adsorption capacity of hydrogels was strongly influenced by AAm, MC, and paraquat concentrations with the highest adsorption capacity (qeq = 14.3 mg g−1) was observed for hydrogels synthesized with 6.0% AAm with 0.75% MC swollen in 45.7 mg L−1 of paraquat solution. Freundlich model performed better than Langmuir model in describing the adsorption isotherm of PAAm‐MC/paraquat system, implying a heterogeneous surface. These results suggest that PAAm‐MC hydrogels are potentially viable absorbents for removal of paraquat pesticide from aqueous solution and cleaning water contaminated with dyes, heavy metals, and others pesticides. © 2009 Wiley Periodicals, Inc. Journal of Appl Polym Sci, 2009

Removal of paraquat from synthetic wastewater using phillipsite–faujasite tuff from Jordan

A phillipsite–faujasite tuff (faujasite) from Jordan has been activated and characterized to evaluate its efficiency in removing paraquat from synthetic wastewater and to specify optimum conditions with maximum efficiency of the faujasite tuff. Noticed variation in CEC is indicated and explained by selectivity of the faujasite to K + and Na +. Removal of paraquat by using faujasite directly gave average removal efficiency equal to 59%. Thermal activation of the samples enhances their performance. The higher is the temperature of activation the higher the efficiency. Treatment of paraquat effluent using faujasite is a good alternative. Na- or K-loading of the original sample give better results. Loading with Ca and Mg however is not recommended because they always exhibit lower efficiency, which might be related to their lower CEC value. Removal of paraquat from wastewater using charcoal and the non-activated faujasite increased efficiency to about 82%. Thermal activated faujasite at 200 °C and 300 °C increased the uptake up to about 93% and 99.5%, respectively. Therefore thermal activation of faujasite is necessary to improve its uptake performance.

Removal of herbicide paraquat from an aqueous solution by adsorption onto spent and treated diatomaceous earth

A spent diatomaceous earth from the beer brewery has been tentatively activated by sodium hydroxide at about 100 °C. The resulting product was used as a novel adsorbent for the adsorption of herbicide paraquat from an aqueous solution in a continuously stirred adsorber and batch flasks, respectively. The results showed that the adsorption process could be well described by the pseudo-second-order reaction model. From the view of the negatively charged surface of diatomaceous earth and cationic property of paraquat, the results were also reasonable to be explained by physical adsorption in the ion-exchange process under the effects of pH and temperature. Further, it was found that the Freundlich model appeared to fit the isotherm data better than the Langmuir model.

Efficient in vitro paraquat removal via irreversible immobilization into zeolite particles.

A new efficient mineral adsorbent, zeolite ZSM-5, has been evaluated for its ability to durably immobilize the herbicide paraquat in conditions simulating acute poisoning by oral ingestion of this toxic compound. The sorption properties have been studied in water, normal saline solution, as well as in artificial and simulated human gastric juices. Uptake kinetics and capacities have been determined and compared to the ion exchange resin Amberlite IR-120. Significant advantages of ZSM-5 over the resin have been demonstrated, especially with respect to long-term retention capability of the toxic herbicide. This solid is a promising primary treatment of acute paraquat poisoning.

Removal of paraquat in aqueous suspension of TiO2 in an immersed UV photoreactor

Experiments were performed to investigate the effect of operating parameters on the photodegradation efficiency of paraquat in a TiO2-suspended photoreactor with immersed UV lamps. TiO2 particles were prepared by a hydrothermal method. The removal rate of paraquat in the reactor was 0.54 mg/l/h with only air-sparging. The removal rate in 24 h with both the UV radiation and air-sparging was 50% higher than that with only the UV radiation. Variations of the paraquat concentration at the UV intensities of 4 and 8 W/m2 decreased slowly with time, but that at 12 W/m2 decreased more rapidly. The removal efficiency at the air-sparging flow rate of 1 //min increased as a UV light intensity increased. pH value in the reactor at the UV intensity of 12 W/m2 decreased with time until 12 h and then increased with time over 12 h.

Removal of paraquat dissolved in a photoreactor with TiO 2 immobilized on the glass-tubes of UV lamps

Experiments were performed to investigate the effects of operating parameters, such as air-inflow rate, UV-light intensity, and film thickness of the photocatalyst, on the photo-decomposition efficiency of paraquat in an immersion-type reactor with TiO 2 immobilized by three kinds of methods on the glass tube of UV lamps. As the number of TiO 2 coating-time increased from 1 to 4, film thickness on the glass tube by a dip-coating method increased from 355 to 1180 Å. The removal efficiency of paraquat using TiO 2 prepared by the hydrothermal method was the highest, being 99% in a 12 h operation of 3-type TiO 2 immobilized by a sol–gel method and a hydrothermal method, including a commercial product P-25, while that in the absence of TiO 2 with only the UV light was the lowest, being 50% in 12 h. The conversion ratios of paraquat at the volumetric flow rates of 5, 10, and 20 mL min −1 were 46%, 25%, and 17% in 18 h, respectively.

Enhanced photocatalytic activity of nafion-coated TiO2.

Photocatalytic degradation (PCD) of aqueous paraquat was accelerated by the addition of either phosphate or sulfate salt. Attachment of these anions to the TiO2 surface possibly results in increased adsorption of the cationic paraquat species and in turn its photocatalysis rate. The same effect was obtained more consistently using the Nafion (an anionic polymer)-coated TiO2. Enhanced PCD of paraquat and some amine compounds was noted. However the anionic and neutral compounds were not affected significantly. Nafion proved to be stable against photocatalysis. It has been suggested that the degradation rate is larger for the cationic compounds with higher pK(B). For a phenol-paraquat-TiO2 system, paraquat degradation did not begin till near-complete phenol removal. Using the Nafion-coated TiO2, both phenol and paraquat degradations started simultaneously. Nevertheless, complete paraquat removal still took longer than phenol.

Removal of paraquat and atrazine from water by montmorillonite-(Ce or Zr) phosphate cross-linked compounds

The adsorption of paraquat (1,1'-dimethyl-4,4'-bipyridilium dichloride) and atrazine (6- chloro-N 2 -ethyl-N 4 -isopropyl-1,3,5-triazine-2,4-diamine) from aqueous solution onto two mont- morillonite-(Ce or Zr) phosphate cross-linked compounds at different temperatures (288 K and 308 K) has been studied using batch experiments. The adsorption isotherms obtained for paraquat on both adsorbents may be classified as H-type of the Giles classification, which suggests that paraquat molecules are strongly adsorbed on the samples. For the adsorption of atrazine, L-type isotherms were obtained for both montmorillonite-(Ce or Zr) phosphate compounds, which suggests that these compounds have a medium affinity for this herbicide. The increase in temperature from 288 K to 308 K did not have any clear effect on the adsorption process of paraquat on either adsorbent whereas atrazine adsorption decreased slightly as temperature increased, possibly due to a mainly physical process. Fourier transform infrared (FTIR) spectroscopic studies revealed that at the pH generated by the adsorbents, the cationic herbicide interacted to a greater extent with the negatively charged surface of the adsorbents than did atrazine. For both herbicides, the Ce-montmorillonite adsorbent showed a higher adsorption capacity than the Zr-montmorillonite adsorbent. # 2000 Society of Chemical Industry

Removal of paraquat and atrazine from water by montmorillonite‐(Ce or Zr) phosphate cross‐linked compounds

Removal of paraquat and atrazine from water by montmorillonite‐(Ce or Zr) phosphate cross‐linked compounds

Adsorption removal of paraquat and diquat onto activated carbon at different adsorption temperature

The efficacy of activated carbon as an oral adsorbent in removing paraquat and diquat from purified water and physiological saline solution at different temperatures was investigated for the primary treatment of acute poisoning. The amounts of paraquat and diquat adsorbed onto activated carbon were large in low temperature condition. The adsorption mode of paraquat and diquat onto activated carbon was mainly physical adsorption. It was recognized that the high adsorption ratio of paraquat and diquat onto activated carbon was obtained by the administration of low temperature suspended solution which was a mixture of activated carbon and gastrointestinal lavage detergent.

Effect of Nicosulfuron on Johnsongrass (Sorghum halepense) Control and Corn (Zea mays) Performance

Field experiments were conducted at two locations in North Carolina during the summer of 1992 to ascertain the reasons for stunted growth of corn noticed occasionally in fields treated POST with nicosulfuron to control dense infestations of johnsongrass. Treatments consisted of nicosulfuron at 35 g ai/ha sprayed POST, either over-top or post-directed only to johnsongrass in a single early application or in sequential applications of 17.5 g/ha. Checks included a hand-weeded, paraquat post-directed to johnsongrass, and non-weeded. Nicosulfuron provided satisfactory control of johnsongrass irrespective of whether applied once or sequentially. Corn yield in nicosulfuron-treated plots was as much as three times greater than in non-treated plots depending on hybrid and location. In the absence of johnsongrass interference, nicosulfuron caused a corn yield reduction of 6 to 9%. However, in the presence of johnsongrass interference, an additional 16 to 26% reduction in yield occurred with a POST application of nicosulfuron. Reductions in corn plant height and dry matter accumulation also were noticed for nicosulfuron treatments compared to post-directed application of paraquat and hand removal of johnsongrass.

Superoxide dismutase level in response to paraquat and high temperature in the cyanobacteriumGloeocapsa sp

Paraquat (methylviologen) at concentrations above 0.05 mM inhibited the growth of photoautotrophic cyanobacteriumGleeocapsa sp. in axenic cultures. The growth rate was not affected by concentrations of 0.01 mM or less. This concentration resulted after a lag period in a moderate increase in superoxide dismutase level. After removal of paraquat, the cyanobacterium continued to generate higher levels of superoxide dismutase. There was a lag period of one hour before resumption of normal enzyme activity. Addition of puromycin at concentration of 0.5 mg cm-3 had no effect on cell survival, but greatly enhanced the sensitivity of the culture to the toxicity of paraquat. The data showed an increase of SOD activity by temperatures above the normal growth temperature level. However, this increase was suppressed by chloramphenicol which revealed that the induction of superoxide dismutase by high temperatures was associated withde novo protein synthesis.