Pesticides removal from water using activated carbons and carbon nanotubes

ABSTRACT

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.

Highlights

• The pesticides forms of application, SD and CP, affect adsorption efficiency.

• Adsorbent point of application, in WTPLS, and contact time are key factors for pesticide removal.

• The primary adsorption mechanism in all the materials tested was chemical.

• The pre-treatment and post-treatment were the most efficient PACs and GACs application forms, respectively.

GRAPHICAL ABSTRACT

KEYWORDS:

• Pulverized activated carbon
• adsorption
• granular activated carbon
• carbon nanotubes
• adsorbent application

Acknowledgments

The authors thank the Alphacarbo LTDA, the Paraná Sanitation Company, SANEPAR, the National Council for Scientific and Technological Development – CNPq and the Coordination of Improvement of Higher Education Personnel – CAPES.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data Availability

The data used to support the findings of this study are included in the article.

Additional information

Funding

This work was supported by CAPES [grant number 001]; CNPQ [grant number 001].