ACTIVATED BIOCHAR FOR THE REMOVAL OF PESTICIDES FROM WASTEWATER: PREPARED FROM, FLAX SHIVES, Linum usitatissimum L.

Abstract

Activated biochar, characterized by high porosity and abundant surface functional groups, has been widely applied to treat wastewater. In this study, flax shives, as an agricultural residue, were converted to activated carbon by pyrolysis followed by chemical activation to remove pesticides, i.e., 2,4-dichlorophenoxyacetic acid (2,4-D) and imidacloprid (IMI) from water. The effects of pyrolysis temperature (300-500 ℃) and residence time (1-3 h) and activation using NaOH at a biochar: NaOH weight ratio of 1:1, 1:2, 1:3 and 1:4 at 700 ℃ for 1.5 h were investigated. The activated biochar (ABC-3) obtained at a biochar: NaOH weight ratio of 1:3 exhibited a specific surface area of 2292 m2g-1 and removed 95 % of 2,4-D and 100% of IMI respectively. The co-adsorption behavior of the two pesticides was also evaluated. Kinetic and isotherm analyses showed that 2,4-D adsorption followed a pseudo-second-order kinetic model and the Freundlich isotherm model while IMI adsorption fitted well with the pseudo-first-order kinetic model and the Langmuir isotherm. Overall, flax shives-derived activated biochar demonstrated strong potential as an efficient adsorbent for pesticide removal.