Multifunctional magnetic bio-nanoporous carbon material based on zero-valent iron, Angelicae Dahuricae Radix slag and graphene oxide: An efficient adsorbent of pesticides

A low-cost and recyclable multifunctional adsorbent for pesticides was successfully prepared based on herb waste (Angelicae Dahuricae Radix slag), nano-zero-valent iron and graphene oxide (AS/NZVI/GO) via facile one-step pyrolysis approach, and applied to remove pesticides from sewage. The AS/NZVI/GO possesses some excellent merits which are beneficial to achieve high adsorption efficiency, including abundant pore structures, lots of surface functional groups and high specific surface area. The maximum adsorption capacity of AS/NZVI/GO for methomyl, isoprocarb and carbaryl up to 59.13, 21.33 and 61.91 mg·g−1, respectively, proved the good adsorption efficiency of AS/NZVI/GO for pesticides. The adsorption mechanism was mainly associated with pore filling, π-π electron-donor–acceptor interaction, hydrogen bonding and electrostatic interaction. The results showed that the pseudo-second-order kinetic model and Freundlich isotherm model showed a better correlation for the experiment data, indicating that the overall rate of the adsorption process was controlled mainly by physical and chemical adsorption. Furthermore, the reusability experiment exhibited that the removal efficiency of AS/NZVI/GO for three pesticides was more than 70% after five recycles. To sum up, it could conclude that the novel AS/NZVI/GO can be used as an efficient adsorbent for the removal of pesticides.