Acessibilidade / Reportar erro

Adsorption Isotherms of Diuron and Hexazinone in Drinking Water Using Four Agro-Industrial Residues

Isotermas de Adsorção de Diuron e Hexazinone em Água Potável Utilizando Quatro Resíduos Agroindustriais

ABSTRACT:

Materials with high organic carbon content are studied for the removal of herbicides from water, such as activated carbon. Low cost alternatives should be investigated for the substitution of this type of material in the removal of herbicides from water. In this context, the aim of this research was to evaluate four agro-industrial residues (white grape bagasse, corn straw, peanut shell and soybean hull) as adsorbents of diuron and hexazinone in drinking water. Samples of drinking water were collected from sources used for human consumption. Five concentrations (1, 2, 3, 4 and 5 mg mL-1) of each herbicide were added to the potable water samples. Each experimental unit consisted of 10 mL of a solution of water and herbicide with 0.1 g of each agro-industrial residue. Sorption was evaluated using the batch equilibrium method. High performance liquid chromatography (HPLC) was used to determine the amount of herbicide present in the aqueous solution. The Kf (Freundlich coefficient) of diuron was higher (2.99-11.93 mmol(1-1/n) L1/n kg-1) than hexazinone (2.31-4.61 mmol(1-1/n) L1/n kg-1) for all adsorbents used. Diuron percentage sorption was higher with white grape bagasse (51.15%) and peanut husk (52.44%), and hexazinone with corn straw (22.77%) and white grape marc (21.48%), than other agro-industrial waste for both herbicides. Even though the sorption of diuron was more pronounced than that of hexazinone, the sorption values obtained in this study were less than 52.44% and considered unsatisfactory in terms of effective removal from contaminated water.

Keywords:
herbicide retention; adsorbents; water remediation; environmental risk

RESUMO:

O uso de materiais com alto teor de carbono orgânico vem sendo estudado para a remoção de herbicidas em água, como o carvão ativado. Poucas alternativas de baixo custo são investigadas para a substituição desse tipo de material na remoção de herbicidas em água. Nesse contexto, o objetivo desta pesquisa foi avaliar resíduos agroindustriais (bagaço de uva branca, palhada de milho, casca de amendoim e casca de soja) como adsorventes do diuron e hexazinone em água potável. Amostras de água potável foram coletadas de fonte para o consumo humano. Foram adicionadas cinco concentrações (1, 2, 3, 4 e 5 mg mL-1) de cada herbicida em amostras de água potável. Os tratamentos consistiram em 10 mL da solução de água e herbicidas com 0,1 g de cada resíduo agroindustrial. A sorção foi avaliada utilizando o método do equilíbrio em batelada. A cromatografia líquida de alta eficiência (HPLC) foi utilizada para determinar a quantidade restante de herbicida em solução. O Kf (coeficiente de Freundlich) para o diuron foi mais pronunciado (9,94-11,93 mmol(1-1/n) L1/n kg-1) do que para o hexazinone (2,31-4,61 mmol(1-1/n) L1/n kg-1) em todos os adsorventes. A sorção percentual de diuron foi maior com bagaço de uva branca (51,15%) e casca de amendoim (52,44%), e a do hexazinone, com palha de milho (22,77%) e bagaço de uva branca (21,48%), em comparação com outros resíduos agroindustriais dos dois herbicidas. Embora a sorção de diuron tenha sido mais pronunciada que a de hexazinone, os valores de sorção obtidos neste estudo foram inferiores a 52,44% e considerados insatisfatórios em termos de remoção eficaz da água contaminada.

Palavras-chave:
retenção de herbicidas; adsorventes; remediação da água; risco ambiental

INTRODUCTION

Herbicide residues found in spring water are commonly derived from the leaching, runoff and volatilization of the compounds applied in agricultural areas and/or from places where washing of packaging is performed. Among the pesticides, the class of herbicides is the most widely used in the world and, in Brazil, are frequently detected in water sources beyond the areas of application (Oliveira Jr et al., 2001Oliveira Jr RS, Koskinen WC, Ferreira FA. Sorption and leaching potential of herbicides on Brazilian soils. Weed Res. 2001;41:97-111.; Santos et al., 2013Santos EA, Correia NM, Botelho RG. Resíduos de herbicidas em corpos hídricos - uma revisão. Rev Bras Herb. 2013;12:188-201.). In Brazil, the contamination of water by pesticides is the second major cause of contamination of water resources after domestic sewage (IBGE, 2011Instituto Brasileiro de Geografia e Estatística - IBGE. Atlas de saneamento 2011. Documento de pesquisa. 2011. [acessado em: 27 abr. 2018]. Disponível em: Disponível em: https://ww2.ibge.gov.br/home/estatistica/populacao/atlas_saneamento/default_zip.shtm .
https://ww2.ibge.gov.br/home/estatistica...
). In view of this, the concern with potability has stimulated research on the remediation of herbicide residues in water, mainly using alternative adsorbent materials derived from organic residues (Gonçalves Jr, 2013Gonçalves Jr AC. Descontaminação e monitoramento de águas e solos na região amazônica utilizando materiais adsorventes alternativos, visando remoção de metais pesados tóxicos e pesticidas. Inclusão Social. 2013;6:105-13.; Silva et al., 2013Silva CR, Gomes TF, Andrade GCRM, Monteiro SH, Dias AC, Zagatto EA, et al. Banana peel as an adsorbent for removing atrazine and ametryne from waters. J Agric Food Chem. 2013;61:2358-63.; Mendes et al., 2017Mendes KF, Freguglia RMO, Martins BAB, Dias R, Pimpinato RF, Tornisielo VL. Bonechar for pesticide removal from drinking water. Scholars J Agric. 2017;4:504-12.)

In areas of sugarcane crops, the effect may be even more pronounced because it is one of the crops where chemical management of weed control is most used (Vivian et al., 2007Vivian R, Queiroz M, Jakelaitis A, Guimarães AA, Reis AA, Carneiro PM, et al. Persistência e lixiviação de ametryn e trifloxysulfuron-sodium em solo cultivado com cana-de-açúcar. Planta Daninha. 2007;25:111-24.). A diuron + hexazinone mixture is commonly used in sugarcane crops for a wider spectrum of control (Kruse et al., 2000Kruse ND, Trezzi MM, Vidal RA. Herbicidas inibidores do EPSPS: revisão de literatura. Rev Bras Herbic. 2000;1:139-46.). Diuron can move to watercourses through surface runoff loaded with soil particles to which it binds, even with low solubility in water (35.6 mg L-1 at 20 oC) (PPDB, 2018Pesticide Properties Database - PPDB. Footprint: creating tools for pesticide risk assessment and management in Europe. Developed by the Agriculture & Environment Research Unit (AERU), University of Hertfordshire, funded by UK national sources and the EU-funded FOOTPRINT project (FP6-SSP-022704). [acessado em: 17 abr. 2018]. Disponível em: Disponível em: http://sitem.herts.ac.uk/aeru/ppdb/en/index.htm .
http://sitem.herts.ac.uk/aeru/ppdb/en/in...
). Inoue et al. (2008Inoue MH, Oliveira Jr RS, Constantin J, Alonso DG, Santana DC. Lixiviação e degradação de diuron em dois solos de textura contrastante. Acta Sci Agron. 2008;30:631-8.) reported the movement capacity of this herbicide within soil, in intense volumes of precipitation (> 60 mm), in soil with lower clay content (100 g kg-1) and organic matter (5.19 g dm-3). In Brazil, Britto et al. (2012Britto FB, Vasco AN, Pereira APS, Méllo Júnior AV, Nogueira LC. Herbicidas no Alto Rio Poxim, Sergipe e os riscos de contaminação dos recursos hídricos. Rev Ci Agron. 2012;43:390-8.) found diuron residues (0.9 µg L-1) in the Poxim River that supplies the city of Aracaju in the State of Sergipe. With regard to hexazinone, residues in water have been found due to its high leaching potential (GUS 4.43) and high solubility in water (33000 mg L-1 at 20 oC) (PPDB, 2018Pesticide Properties Database - PPDB. Footprint: creating tools for pesticide risk assessment and management in Europe. Developed by the Agriculture & Environment Research Unit (AERU), University of Hertfordshire, funded by UK national sources and the EU-funded FOOTPRINT project (FP6-SSP-022704). [acessado em: 17 abr. 2018]. Disponível em: Disponível em: http://sitem.herts.ac.uk/aeru/ppdb/en/index.htm .
http://sitem.herts.ac.uk/aeru/ppdb/en/in...
). The physico-chemical characteristics of herbicides may indicate different behaviors in the environment; these properties are presented in Table 1.

Table 1
Structural formulas and physicochemical properties of herbicides

Armas et al. (2007Armas ED, Monteiro RTR, Antunes PM, Santos MAPF, Camargo PB, Abakerli RB. Diagnóstico espaço-temporal da ocorrência de herbicidas nas águas superficiais e sedimentos do Rio Corumbataí e principais afluentes. Quím Nova. 2007;30:1119-27.) found hexazinone residues (0.5 µg L-1) in the Corumbataí River, which is part of a hydrographic supply network in the State of São Paulo, Brazil. In Brazil, there are no maximum residue limits allowed for both herbicides (Brasil, 2005BRASIL. Conselho Nacional do Meio Ambiente. Resolução no 357, de 17 de março de 2005. Dispõe sobre a classificação dos corpos de água e diretrizes ambientais para o seu enquadramento, bem como estabelece as condições e padrões de lançamento de efluentes, e dá outras providências. Diário Oficial [da] República Federativa do Brasil, Brasília, DF, 18 mar. 2005. [acessado em: 26 fev. 2018]. Disponível em: Disponível em: http://www.mma.gov.br/conama/res/res05/res35705 .
http://www.mma.gov.br/conama/res/res05/r...
). According to Orlando et al. (2014Orlando JL, et al. Dissolved pesticide concentrations entering the Sacramento-San Joaquin Delta from the Sacramento and San Joaquin Rivers, California, 2012-13. USGS Unnumbered Series. 2014;876:28. ), diuron was detected in 72% and hexazinone in 100% of the Sacramento-San Joaquin River delta surface water samples in California, with a maximum detected concentration of 0.695 µg L-1 of 0.984 µg L-1, respectively for diuron and hexazinone. Maximum permissible residue levels in the United States, which are set to prevent adverse health effects, are 100 µg L-1 for diuron and 2000 µg L-1 for hexazinone (PAN, 2018Pesticide Action Network - PAN. Pesticide Database. [acessado em: 26 jun. 2018]. Disponível em: Disponível em: http://www.pesticideinfo.org/ .
http://www.pesticideinfo.org/...
).

The presence of herbicide residues in water can lead to contamination and toxicological effects in organisms. Studies have reported the killing of algae (Perschbacher and Ludwig, 2004Perschbacher PW, Ludwig GM. Effects of diuron and other aerially applied cotton herbicides and defoliants on the plankton communities of aquaculture ponds. Aquaculture. 2004;233:197-203.) and effects on oyster gametogenesis (Akcha et al., 2016Akcha F, Barranger A, Bachère E, Berthelin CH, Piquemal D, Alonso P, et al. Effects of an environmentally relevant concentration of diuron on oyster genitors during gametogenesis: responses of early molecular and cellular markers and physiological impacts. Environ Sci Pollut Res. 2016; 23: 8008-20.; Rondon et al., 2016Rondon R, Akcha F, Alonso P, Menard D, Rouxel J, Montagnani C, et al. Transcriptional changes in Crassostrea gigas oyster spat following a parental exposure to the herbicide diuron. Aquatic Toxicology. 2016;175:47-55.) in the presence of diuron. Changes in the phytoplankton community and decrease in zooplankton and micro-invertebrate species have been reported with chronic exposure to diuron and hexazinone (Hasenbein et al., 2017Hasenbein S, Peralta J, Lawler SP, Connon RE. Environmentally relevant concentrations of herbicides impact non-target species at multiple sublethal endpoints. Sci Total Environ. 2017;607-8:733-43.).

Adsorption, photocatalysis and/or advanced oxidation processes can be used as strategies for the removal of herbicides from drinking water (Baird, 2002Baird C. Química ambiental. 2nd ed. Porto Alegre: Artmed; 2002. 622p.). Among these, adsorption using biomass from agro-industrial residues (biosorbents) is an advantageous alternative in the sorption of herbicides from water (Hu et al., 2016Hu J, Shang R, Frolova M, Heijman B, Rietveld L. Pharmaceutical adsorption from the primary and secondary effluents of a wastewater treatment plant by powdered activated carbon. Desalin Water Treat. 2016;57:21304-13.). These are low cost materials which are generated in large quantities, have limited generation of sludge in environment and have comparable efficiency to conventional adsorbents (Chaukura et al., 2016Chaukura N, Gwenzi W, Tavengwa N, Manyuchi MM. Biosorbents for the removal of synthetic organics and emerging pollutants: opportunities and challenges for developing countries. Environ Dev. 2016;19:84-9.; Homem et al., 2018Homem NC, Vieira AMS, Bergamasco R, Vieira MF. Low-cost biosorbent based on moringa oleifera residues for herbicide atrazine removal in a fixed bed column. Can J Chem Eng. 2018;9999:1-11. ). Silva et al. (2013Silva CR, Gomes TF, Andrade GCRM, Monteiro SH, Dias AC, Zagatto EA, et al. Banana peel as an adsorbent for removing atrazine and ametryne from waters. J Agric Food Chem. 2013;61:2358-63.) reported >90% removal efficiency of atrazine and simazine from drinking water using banana peel residues. In this perspective, research into various organic materials, such as sunflower seeds, rice hulls, beet pulp and corn cob, has been carried out and satisfactory results have been obtained on the removal of herbicides (trifluralin, glyphosate, diuron and 3,4-DCA) from water (Huguenot et al., 2010Huguenot D. Selection of low cost materials for the sorption of copper and herbicides as single or mixed compounds in increasing complexity matrices. J Hazard Mater. 2010; 182: 18-26.; Rojas et al., 2015Rojas R, Morillo J, Usero J, Vanderlinden E, El Bakouri H. Adsorption study of low-cost and locally available organic substances and a soil to remove pesticides from aqueous solutions. J Hydrol. 2015;520:461-72.).

Adsorption of herbicides using alternative materials can be employed directly or in combination with other techniques to improve the efficiency of removal of pollutants from water (Zolgharnein et al., 2011Zolgharnein J, Shahmoradi A, Ghasemi J. Pesticides removal using conventional and low cost adsorbents: a review. Clean-Soil, Air, Water. 2011;39:1105-19.). The investigation of the adsorptive capacity of organic wastes to the herbicides is promising in the remediation of these compounds of the environment. In view this, the objective of this research was to evaluate the retention capacity of the agro-industrial residues, white grape marc, corn straw, soybean hulls and peanut hulls, in adsorbing diuron and hexazinone herbicides from drinking water.

MATERIAL AND METHODS

Drinking water samples

Samples of drinking water were collected directly from a household faucet in Piracicaba, São Paulo, Brazil. The faucet was opened by filling a 1.0 L bottle with the same water supplied to consumers from the city’s water supply network as water for human consumption. The vessel was stored for 24 h at room temperature until contamination was initiated. Information provided by the water supply network of the municipality itself was used for details of the physico-chemical properties of the collected water samples (Table 2).

Table 2
Selected properties of drinking water quality.

Herbicides

Stock solutions of diuron and hexazinone were prepared from their analytical standards, with 99.5 and 99.9% chemical purity, respectively (Sigma Aldrich, St. Louis, MO, USA). All stock solutions were prepared at a concentration of 1000 µg mL-1 in acetonitrile. Working solutions with five concentrations (1, 2, 3, 4 and 5 µg mL-1) of each herbicide were also prepared. For each treatment, 0.25, 0.5, 0.75, 1.0, 1.25 and 3.15 mL of each working solution was added to 10 mL samples of contaminated drinking water. The five increasing concentrations were used to adjust the adsorption isotherms.

Agro-industrial waste

White grape bagasse, corn straw (crop residue without spikes), peanut shells and soybean hulls were used. All materials were milled and homogenized in a mechanical mill and sieved through a 2 mm mesh. A 0.1 g quantity of each material was added to 10 mL of potable water, previously contaminated with herbicide, in 50 mL Teflon tubes, resulting in a 1:100 w/v mixture. The tubes were sealed with a screw-cap. The characteristics of the residues used in this study are presented in Table 3.

Table 3
Properties physicochemical of agro-industrials waste

Experimental design

The experiment was based on a completely randomized design with a 4×2 factorial scheme, involving four agro-industrial residues (white grape bagasse, corn straw, peanut shelsl and soybean hulls) and two herbicides (diuron and hexazinone). Three replicates were used for each treatment.

Removal of herbicides from water

The adsorption studies were performed at room temperature (20 ± 2 oC) with the agitator set at 200 rpm. After the tubes were shaken for 24 h to achieve horizontal table equilibration, the samples were centrifuged at 7000 rpm for 5 min at 4 oC. Aliquots (1 mL) of supernatants from each vial were filtered through a 300 CW PTFE filter (0.45 µm) for HPLC analysis, so that the supernatant was discarded, leaving only the vegetable residue. The concentration of each herbicide present in each potable water sample was determined. The results were expressed as mg of herbicide per mL of drinking water.

Chromatographic analysis

The chromatographic method used, described by Mendes et al. (2017Mendes KF, Freguglia RMO, Martins BAB, Dias R, Pimpinato RF, Tornisielo VL. Bonechar for pesticide removal from drinking water. Scholars J Agric. 2017;4:504-12.) with some modifications, was validated and met the requirements of the Brazilian national guidelines (Anvisa, 2012Agência Nacional de Vigilância Sanitária - Anvisa. Resolução. RDC Nº 4, 18 de janeiro, 2012. Dispõe sobre os critérios para a realização de estudos de resíduos de agrotóxicos para fins de registro de agrotóxicos no Brasil. Diário Oficial da União, Seção 1: Brasília, DF, Brasil, 40-46, 2012. ) and the European Union (SANTE, 2016SANTE, 11945/2015. Guidance document on analytical quality control and validation procedures for pesticide residues analysis in food and feed. European Union: European Commission Health & Consumer Protection Directorate-General; 2016. 46p.). Chromatographic determinations of the initial and final concentrations (after adsorption) of the herbicides in the samples were performed by HPLC (Agilent Technologies®, model 1200 series), with a UV-Vis detector (Agilent Technologies®) and a C18 column (3.5 × 4.6 × 100 mm di; Kromasi). Chromatographic conditions for analysis were as follows: water (with orthophosphoric acid added) and acetonitrile (40:60 v/v) as the mobile phase; flow rate of 1 mL min-1; injection volume of 20 µL; column temperature of 35 oC and 242 nm wavelength. Chemstation® software was used for data analysis.

Linear adsorption model

The adsorption coefficients were calculated using the following equation: Kd = Cs/Ce, where Cs is the concentration of herbicide adsorbed onto the agro-industrial residue (µmol kg-1) and Ce is the equilibrium herbicide concentration in the liquid phase (µmol L-1). The adsorption data were normalized to the organic carbon (OC) content of agro-industrial waste and Koc was calculated from the sorption adsorption coefficient using the following formula: Koc = (Kd/% OC) × 100%, where %OC is the percentage of OC in organic materials. The units of Kd and Koc are represented in L kg-1.

Freundlich adsorption isotherm model

The adsorption coefficients, Kf and 1/n, were calculated by the Freundlich isotherms as follows: Cs = Kf x Ce1/n, where Cs is the concentration (mg g-1) of the herbicide sorbed by the soil after equilibration, Kf is the Freundlich equilibrium constant (µmol (1-1/n) L1/n kg-1), Ce is the concentration of herbicide (mg L-1) after equilibrium in solution, and 1 n is the degree of linearity of the isotherm. The normalization of these values for the organic carbon (OC) content of the agro-industrial wastes was performed, so that the Kfoc was calculated from the Freundlich equilibrium constant, using the following formula: Kfoc = (Kf /%OC) × 100%, where % OC is the percentage of OC in organic materials. The units for Kf and Kfoc are represented in µmol (1-1/n) L1/n kg-1.

Statistical analysis

The adsorption data for diuron and hexazinone were adjusted for linear and non-linear regressions by the Freundlich model, as previously described. Figures were plotted using Sigma Plot® (version 10.0 for Windows, Systat Software Inc., Point Richmond, CA, USA).

RESULTS AND DISCUSION

Validation of the chromatographic method

The areas of the chromatographic peaks and the applied concentrations were used to determine the following validation parameters: selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), and precision and accuracy of the method. These parameters indicated the reliability of the method used (ANVISA, 2012Agência Nacional de Vigilância Sanitária - Anvisa. Resolução. RDC Nº 4, 18 de janeiro, 2012. Dispõe sobre os critérios para a realização de estudos de resíduos de agrotóxicos para fins de registro de agrotóxicos no Brasil. Diário Oficial da União, Seção 1: Brasília, DF, Brasil, 40-46, 2012. ; SANTE, 2016SANTE, 11945/2015. Guidance document on analytical quality control and validation procedures for pesticide residues analysis in food and feed. European Union: European Commission Health & Consumer Protection Directorate-General; 2016. 46p.). The selectivity or identification of each herbicide contained in the samples was by means of the retention time for each one; this was 4.44 min for hexazinone and 5.36 min for the diuron. At concentrations of 1, 2, 3, 4 and 5 µg mL-1 for both hexazinone and diuron, the correlation coefficient (R²) was higher than 0.99. The calibration curves generated were y = 65.08308x + 10.45979 for hexazinone and y = 86.52990x + 9.67090 for diuron. The LOD was 0.1 µg mL-1 and the LOQ was 0.2 µg mL-1 for the two herbicides. These limits indicate the minimum level of detection of the substances by the equipment and the precision of the quantification, respectively Values above 99% were recovered (Table 4), consistent with the values determined by ANVISA (2012Agência Nacional de Vigilância Sanitária - Anvisa. Resolução. RDC Nº 4, 18 de janeiro, 2012. Dispõe sobre os critérios para a realização de estudos de resíduos de agrotóxicos para fins de registro de agrotóxicos no Brasil. Diário Oficial da União, Seção 1: Brasília, DF, Brasil, 40-46, 2012. ) and SANTE (2016SANTE, 11945/2015. Guidance document on analytical quality control and validation procedures for pesticide residues analysis in food and feed. European Union: European Commission Health & Consumer Protection Directorate-General; 2016. 46p.); the recovery percentage (R%) was 70-120% and coefficient of variation (CV%) <20.

Table 4
Recovery levels (3 injections of each replicate) of the proposed method for the herbicides (5.0 µg ml-1) in drinking water samples

Adsorption isotherms of hexazinone and diuron in drinking water with four agro-industrial residues

The high coefficient of determination for the linear model (R²> 0.93) and the significant variables indicated the reliability of the results provided by this model (Table 5). The values of the partition coefficient Kd (linear model) for hexazinone with agro-industrial waste were in the range 0.40-1.64 L kg-1. For diuron, the sorption values were 2.85-8.61 L kg-1 This normalized coefficient for the OC content of agro-industrial waste (Koc) indicated higher retention hexazinone and diuron with white grape bagasse (37.79 and 178.92 L kg-1, respectively) than other agro-industrial waste. This organic material had a higher OC content (47.78%) than the others (Table 3). In relation to materials with high OC content, Rojas et al. (2014Rojas R, Vanderlinden E, Morillo J, Usero J, El Bakouri H. Characterization of sorption processes for the development of low-cost pesticide decontamination techniques. Sci Total Environ. 2014;488:124-35.) indicated the high potential of rice husk for sorption of simazine in solution (Koc = 194 L kg-1); using 1 g of the material resulted in 73.8% maximum adsorption of the herbicide due to its OC of 46.21%, which is similar to the OC of white grape marc used in this study.

Table 5
Linear adsorption parameters for the hexazinone and diuron to agro-industrial waste in drinking water

The Freundlich equation was adequate for describing the adsorption of hexazinone and diuron at agro-industrial waste from drinking water (R²> 0.92) (Table 6). The values of 1/n for hexazinone were in the range 0.14-0.81 and 0.66-0.95 for diuron, indicating the behavior of adsorption isotherms of type L (1/n <1) (Giles et al., 1960Giles CH, MacEwan TH, Nakhwa SN, Smith D. A system of classification of solution adsorption isotherms. J Chem Soc. 1960;111:3973-93.). That, according to Limousin et al. (2007Limousin G, Gaudet JP, Charlet L, Szenknect S, Barthès V, Krimissa M. Sorption isotherms: a review on physical bases, modeling and measurement. Applied Geochem. 2007;22:249-75.), represents the progressive saturation of the adsorption matrix. The Freundlich isotherms showed a very similar behavior to the linear model (Figure 1), indicating that the adsorption of these herbicides by organic materials can be explained by the two models, in which increased adsorption to organic residues rises with increasing concentrations of the herbicides.

Table 6
Freundlich adsorption parameters for the hexazinone and diuron to agro-industrial waste in drinking water

Figure 1
Freundlich adsorption and linear isotherms of hexazinone and diuron in agriculture waste in the drinking water.

As for the adsorptive capacity of the organic residues, after adjustment to the Freundlich model, Kf values were lower for hexazinone (2.31-4.61 µmol (1-1/n) L1/n kg-1) than for the diuron (2.99-11.93 µmol (1-1/n) L1/n kg-1) with all materials (Table 6). Soybean hulls presented Kf values of 2.31 and 2.99 µmol (1-1/n) L1/n kg-1 for hexazinone and diuron, respectively, similar for both herbicides, while the other materials were better adsorbents for diuron (p <0.05) (Table 6). When the Kf values were adjusted to the OC content of the agro-industrial waste, notable herbicide adsorption values were reported for corn straw with hexazinone (Kfoc = 104.69 µmol(1-1/n) L1/n kg-1) and peanut shells with diuron (Kfoc = 250.60 µmol(1-1/n) L1/n kg-1).

In general, the adsorption percentages of the residues were 2.38, 2.04, 3.64 and 1.29 times higher for white grape marc, corn straw, peanut shell and soybean hull, respectively, with diuron when compared to hexazinone. This is due to diuron being more apolar (log Kow 2.87) and hexazinone being less apolar (log Kow 1.17), which gives for the first a higher adsorption affinity with OC present in the organic residues (Table 1). The materials with the highest percentage of adsorption were white grape bagasse and peanut shells (51.15 and 52.44%, respectively) with diuron. Rojas et al. (2014Rojas R, Vanderlinden E, Morillo J, Usero J, El Bakouri H. Characterization of sorption processes for the development of low-cost pesticide decontamination techniques. Sci Total Environ. 2014;488:124-35.), studying the removal of different herbicides from water by organic materials, indicated that the adsorption capacity of atrazine and alachlor increased with the hydrophobic character of each and decreased with the solubility of the molecule. In the case of a hydrophobic herbicide similar to diuron, Rodríguez-Cruz (2012Rodríguez-Cruz MS. Adsorption of pesticides by sewage sludge, grape marc, spent mushroom substrate and by amended soils. Int J Environ Anal Chem. 2012;92:933-48.) reported high adsorption of linuron using grape marc (Kf = 92.9 µg mL-1) when applied to the soil. Similarly, Marín-Benito et al. (2014Marín-Benito JM, et al. Effect of different organic amendments on the dissipation of linuron, diazinon and myclobutanil in an agricultural soil incubated for different time periods. Sci Total Environ. 2014;476:611-21.) also found greater retention and reduction in leaching of linuron by adding organic materials to the soil, such as grape bagasse.

With the intention of removing this herbicide from drinking water, our results indicated 22.77% of hexazinone adsorption with corn straw and 21.48% with white grape bagasse. However, hexazinone adsorption values were low relative to diuron. Due to the high solubility of hexazinone (33,000 mg L-1 at 20 oC) it is often found in bodies of water in Brazil (Santos et al., 2013Santos EA, Correia NM, Botelho RG. Resíduos de herbicidas em corpos hídricos - uma revisão. Rev Bras Herb. 2013;12:188-201.). In this view, other materials are reported in the literature to be adsorbents of this herbicide from drinking water, such as bonechar (biochar derived from bovine bones) indicated by Mendes et al. (2017Mendes KF, Freguglia RMO, Martins BAB, Dias R, Pimpinato RF, Tornisielo VL. Bonechar for pesticide removal from drinking water. Scholars J Agric. 2017;4:504-12.), also using drinking water. The authors found 78% and 100% removal of hexazinone with 0.1 g and 1 g of bonechar, respectively, when added to 10 mL of drinking water containing the contaminant. Another means of removing this herbicide was reported by Hunter and Shaner (2012Hunter WJ, Shaner DL. Removing hexazinone from groundwater with microbial bioreactors. Current microbiology. 2012;64:405-11.), using microbial aerobic reactors (nitrogen limited) with sand that stimulate microbial growth; this removed more than 95% of hexazinone from the water, being able to remediate high quantities of the herbicide (100 mg L-1).

The different ways in which agro-industrial waste can be used present several possibilities. They may be related to herbicide retention and/or induction of microbiota activation and degradation of these compounds are interesting. Biobed systems are used to reduce the leaching of some phenylureas, such as linuron, diuron and methabenzthiazuron, in the biopurification of the waters used in agriculture, especially during the washing of application tanks (Spliid et al., 2006Spliid NH, Helweg A, Heinrichson K. Leaching and degradation of 21 pesticides in a full-scale model biobed. Chemosphere. 2006;65:2223-32.). Another use is in filtration systems in continuous water flow systems, replacing activated carbon. Dantas et al. (2009Dantas AB, Paschoalato CFPR, Ballejo RR, Bernardo L. Pré-oxidação e adsorção em carvão ativado granular para remoção dos herbicidas diuron e hexazinona de água subterrânea. Eng Sanit Ambient. 2009;14:373-80.) indicated higher adsorption affinity of diuron to activated carbon than that of hexazinone in this type of system. However, not all materials containing large amounts of carbon may be indicated in herbicide removal, as in the case of the four materials tested in this study, even using these systems. In general, hexazinone reached a maximum adsorption of only a quarter of the total applied (mean of concentrations), already the half-dose applied diuron. This finding indicates that the quantities removed by agro-industrial waste are insufficient for the effective removal of the herbicides from water in which these contaminants are present.

Of the agro-industrial wastes used in this study, white grape marc, peanut hulls and corn straw showed higher retention of the herbicides diuron and hexazinone from drinking water. However, the adsorbed amounts were not sufficient for the total removal of these contaminants from potable water. We demonstrated the potential of white grape marc for apolar herbicides, which present greater risks to the environment when they reach groundwater and surface water. Investigations of the potential retention and optimal use of agro-industrial wastes, which are abundant and are associated with low cost, are essential to reducing the environmental impact of herbicides and pesticides in general.

ACKNOWLEDGMENT

The authors would like to thank the Foundation for Research Support of the State of São Paulo (FAPESP), Process 2017/20402-7 and Coordination of Improvement of Higher Education Personnel - Brazil (CAPES) - Financing Code 001, for the financial support.

REFERENCES

  • Akcha F, Barranger A, Bachère E, Berthelin CH, Piquemal D, Alonso P, et al. Effects of an environmentally relevant concentration of diuron on oyster genitors during gametogenesis: responses of early molecular and cellular markers and physiological impacts. Environ Sci Pollut Res. 2016; 23: 8008-20.
  • Agência Nacional de Vigilância Sanitária - Anvisa. Resolução. RDC Nº 4, 18 de janeiro, 2012. Dispõe sobre os critérios para a realização de estudos de resíduos de agrotóxicos para fins de registro de agrotóxicos no Brasil. Diário Oficial da União, Seção 1: Brasília, DF, Brasil, 40-46, 2012.
  • Armas ED, Monteiro RTR, Antunes PM, Santos MAPF, Camargo PB, Abakerli RB. Diagnóstico espaço-temporal da ocorrência de herbicidas nas águas superficiais e sedimentos do Rio Corumbataí e principais afluentes. Quím Nova. 2007;30:1119-27.
  • Baird C. Química ambiental. 2nd ed. Porto Alegre: Artmed; 2002. 622p.
  • BRASIL. Conselho Nacional do Meio Ambiente. Resolução no 357, de 17 de março de 2005. Dispõe sobre a classificação dos corpos de água e diretrizes ambientais para o seu enquadramento, bem como estabelece as condições e padrões de lançamento de efluentes, e dá outras providências. Diário Oficial [da] República Federativa do Brasil, Brasília, DF, 18 mar. 2005. [acessado em: 26 fev. 2018]. Disponível em: Disponível em: http://www.mma.gov.br/conama/res/res05/res35705
    » http://www.mma.gov.br/conama/res/res05/res35705
  • Britto FB, Vasco AN, Pereira APS, Méllo Júnior AV, Nogueira LC. Herbicidas no Alto Rio Poxim, Sergipe e os riscos de contaminação dos recursos hídricos. Rev Ci Agron. 2012;43:390-8.
  • Chaukura N, Gwenzi W, Tavengwa N, Manyuchi MM. Biosorbents for the removal of synthetic organics and emerging pollutants: opportunities and challenges for developing countries. Environ Dev. 2016;19:84-9.
  • Dantas AB, Paschoalato CFPR, Ballejo RR, Bernardo L. Pré-oxidação e adsorção em carvão ativado granular para remoção dos herbicidas diuron e hexazinona de água subterrânea. Eng Sanit Ambient. 2009;14:373-80.
  • Giles CH, MacEwan TH, Nakhwa SN, Smith D. A system of classification of solution adsorption isotherms. J Chem Soc. 1960;111:3973-93.
  • Gonçalves Jr AC. Descontaminação e monitoramento de águas e solos na região amazônica utilizando materiais adsorventes alternativos, visando remoção de metais pesados tóxicos e pesticidas. Inclusão Social. 2013;6:105-13.
  • Hasenbein S, Peralta J, Lawler SP, Connon RE. Environmentally relevant concentrations of herbicides impact non-target species at multiple sublethal endpoints. Sci Total Environ. 2017;607-8:733-43.
  • Homem NC, Vieira AMS, Bergamasco R, Vieira MF. Low-cost biosorbent based on moringa oleifera residues for herbicide atrazine removal in a fixed bed column. Can J Chem Eng. 2018;9999:1-11.
  • Hu J, Shang R, Frolova M, Heijman B, Rietveld L. Pharmaceutical adsorption from the primary and secondary effluents of a wastewater treatment plant by powdered activated carbon. Desalin Water Treat. 2016;57:21304-13.
  • Huguenot D. Selection of low cost materials for the sorption of copper and herbicides as single or mixed compounds in increasing complexity matrices. J Hazard Mater. 2010; 182: 18-26.
  • Hunter WJ, Shaner DL. Removing hexazinone from groundwater with microbial bioreactors. Current microbiology. 2012;64:405-11.
  • Instituto Brasileiro de Geografia e Estatística - IBGE. Atlas de saneamento 2011. Documento de pesquisa. 2011. [acessado em: 27 abr. 2018]. Disponível em: Disponível em: https://ww2.ibge.gov.br/home/estatistica/populacao/atlas_saneamento/default_zip.shtm
    » https://ww2.ibge.gov.br/home/estatistica/populacao/atlas_saneamento/default_zip.shtm
  • Inoue MH, Oliveira Jr RS, Constantin J, Alonso DG, Santana DC. Lixiviação e degradação de diuron em dois solos de textura contrastante. Acta Sci Agron. 2008;30:631-8.
  • Kruse ND, Trezzi MM, Vidal RA. Herbicidas inibidores do EPSPS: revisão de literatura. Rev Bras Herbic. 2000;1:139-46.
  • Limousin G, Gaudet JP, Charlet L, Szenknect S, Barthès V, Krimissa M. Sorption isotherms: a review on physical bases, modeling and measurement. Applied Geochem. 2007;22:249-75.
  • Marín-Benito JM, et al. Effect of different organic amendments on the dissipation of linuron, diazinon and myclobutanil in an agricultural soil incubated for different time periods. Sci Total Environ. 2014;476:611-21.
  • Mendes KF, Freguglia RMO, Martins BAB, Dias R, Pimpinato RF, Tornisielo VL. Bonechar for pesticide removal from drinking water. Scholars J Agric. 2017;4:504-12.
  • Oliveira Jr RS, Koskinen WC, Ferreira FA. Sorption and leaching potential of herbicides on Brazilian soils. Weed Res. 2001;41:97-111.
  • Orlando JL, et al. Dissolved pesticide concentrations entering the Sacramento-San Joaquin Delta from the Sacramento and San Joaquin Rivers, California, 2012-13. USGS Unnumbered Series. 2014;876:28.
  • Pesticide Action Network - PAN. Pesticide Database. [acessado em: 26 jun. 2018]. Disponível em: Disponível em: http://www.pesticideinfo.org/
    » http://www.pesticideinfo.org/
  • Perschbacher PW, Ludwig GM. Effects of diuron and other aerially applied cotton herbicides and defoliants on the plankton communities of aquaculture ponds. Aquaculture. 2004;233:197-203.
  • Pesticide Properties Database - PPDB. Footprint: creating tools for pesticide risk assessment and management in Europe. Developed by the Agriculture & Environment Research Unit (AERU), University of Hertfordshire, funded by UK national sources and the EU-funded FOOTPRINT project (FP6-SSP-022704). [acessado em: 17 abr. 2018]. Disponível em: Disponível em: http://sitem.herts.ac.uk/aeru/ppdb/en/index.htm
    » http://sitem.herts.ac.uk/aeru/ppdb/en/index.htm
  • Rodríguez-Cruz MS. Adsorption of pesticides by sewage sludge, grape marc, spent mushroom substrate and by amended soils. Int J Environ Anal Chem. 2012;92:933-48.
  • Rojas R, Morillo J, Usero J, Vanderlinden E, El Bakouri H. Adsorption study of low-cost and locally available organic substances and a soil to remove pesticides from aqueous solutions. J Hydrol. 2015;520:461-72.
  • Rojas R, Vanderlinden E, Morillo J, Usero J, El Bakouri H. Characterization of sorption processes for the development of low-cost pesticide decontamination techniques. Sci Total Environ. 2014;488:124-35.
  • Rondon R, Akcha F, Alonso P, Menard D, Rouxel J, Montagnani C, et al. Transcriptional changes in Crassostrea gigas oyster spat following a parental exposure to the herbicide diuron. Aquatic Toxicology. 2016;175:47-55.
  • SANTE, 11945/2015. Guidance document on analytical quality control and validation procedures for pesticide residues analysis in food and feed. European Union: European Commission Health & Consumer Protection Directorate-General; 2016. 46p.
  • Santos EA, Correia NM, Botelho RG. Resíduos de herbicidas em corpos hídricos - uma revisão. Rev Bras Herb. 2013;12:188-201.
  • Silva CR, Gomes TF, Andrade GCRM, Monteiro SH, Dias AC, Zagatto EA, et al. Banana peel as an adsorbent for removing atrazine and ametryne from waters. J Agric Food Chem. 2013;61:2358-63.
  • Spliid NH, Helweg A, Heinrichson K. Leaching and degradation of 21 pesticides in a full-scale model biobed. Chemosphere. 2006;65:2223-32.
  • Vivian R, Queiroz M, Jakelaitis A, Guimarães AA, Reis AA, Carneiro PM, et al. Persistência e lixiviação de ametryn e trifloxysulfuron-sodium em solo cultivado com cana-de-açúcar. Planta Daninha. 2007;25:111-24.
  • Zolgharnein J, Shahmoradi A, Ghasemi J. Pesticides removal using conventional and low cost adsorbents: a review. Clean-Soil, Air, Water. 2011;39:1105-19.

Data availability

Data citations

Pesticide Action Network - PAN. Pesticide Database. [acessado em: 26 jun. 2018]. Disponível em: Disponível em: http://www.pesticideinfo.org/

Publication Dates

  • Publication in this collection
    10 Feb 2020
  • Date of issue
    2020

History

  • Received
    07 Nov 2018
  • Accepted
    25 Apr 2019
Sociedade Brasileira da Ciência das Plantas Daninhas Departamento de Fitotecnia - DFT, Universidade Federal de Viçosa - UFV, 36570-000 - Viçosa-MG - Brasil, Tel./Fax::(+55 31) 3899-2611 - Viçosa - MG - Brazil
E-mail: rpdaninha@gmail.com