RESUMO
The conventional water treatment technique (CT) widely applied cannot alone remove pesticides efficiently from water. Therefore, this work aimed to provide technical and scientific support for the association of pulverized activated carbon (PACs), granular activated carbon (GACs), and carbon nanotubes (CNT) with CT concerning atrazine (ATZ), simazine (SMZ), and diuron (DIU) removal. Actual conditions of pre/during, and post-treatment points of application, within water production process line, in water treatment plants (WTPs), using the pesticides in two forms, commercial product (CP) and analytical standard (SD). It was possible to demonstrate significant differences regarding the removal of ATZ, SMZ, and DIU in their SD and CP forms for the PACs, GACs, and CNTs. The minimum dosage of CNT required for adequate adsorption of all pesticides was superior to 160 mg. L-1; is 400% higher than the minimum dosage of 40 mg. L-1 is required for PAC application. ATZ, SMZ, and DIU in the SD form were more efficiently removed with percentages superior to 96.4% for ATZ, 98.2% for SMZ, and 99.1% for DIU. The characteristics of the adsorptive materials did not guide the adsorption efficacy. Instead, chemical interaction, contact time, and point application were critical factors. The pre-treatment and post-treatment applications were the most efficient, with removals oscillating from 97.7% to 100% for ATZ, 97.7% to 100% for SMZ, and 99.1 to 100% for DIU PAC and GAC, respectively.
RESUMO
Pesticides present in water resources can cause adverse health effects even in low concentrations, due to their bio-accumulative character. Therefore, the challenge for drinking water production increases, due to the limitations of conventional water treatment technologies in the removal of small molecular weight dissolved compounds. This work aimed to provide technical and scientific support for the selection of pulverized activated carbon - PACs, granular activated carbon - GACs, and carbon nanotubes - CNT concerning atrazine - ATZ, simazine - SMZ, and diuron - DIU adsorption for application in water treatment plants, considering two forms of application commercial product - CP and analytical standard - SD. These forms of application were tested aiming to verify the influence of the purity of the products used in experiments on the adsorption efficiency. It was possible to verify the adsorption efficiencies were not guided only by the characteristics of the adsorptive materials used, and that the selection should not be carried out only based on the, specific superficial area - BET size and distribution of specific pore volume. The isotherms demonstrated that the parameter Kf associated with the results of the selection experiment can be considered an alternative technical tool of simple application and sufficient for this purpose. Also, the capacity of activated carbons - ACs and nanomaterials - NMs were affected by the application of the compounds, highlighting the importance of using commercial product - CP in scientific research and technical investigations.Hightlights The pesticides efficiency removal was affected due to the forms of application, SD and CP;The parameters IN and MBI were not decisive in the selection of the activated carbon;The main adsorption mechanism in all the materials was chemical;GAC was the most efficient adsorbent in the removal of the pesticides;An adequate adsorbent selection is crucial for satisfactory removal of pesticides in water.
