Microporous activated carbon from the fruits of the invasive species Hovenia dulcis to remove the herbicide atrazine from waters

Abstract

The species Hovenia dulcis has become a major issue for the Brazilian biome due to its high adaptation and accelerated propagation, putting the local biodiversity at risk. In this sense, this study sought to generate a new purpose for the fruits of this peculiar species. They were carbonized with ZnCl2 to produce porous activated carbon, which was used to remove the herbicide atrazine from aqueous solutions. The Hovenia dulcis activated carbon (Hd-AC) presented a surface area of 898.4 m2/g, with narrow pores with an average diameter of 1.24 nm and a pore volume of 0.296 cm3 g−1. Hd-AC for atrazine adsorption was efficient at a pH of 6.0 for an adsorbent dosage of 0.5 g/L, where the adsorption capacity was 58 mg g−1 at 328 K. The isothermal curves showed a good adjustment to the Freundlich isotherm. The thermodynamic results indicated that herbicide adsorption was spontaneous, favorable, and endothermic (ΔH° = 8.21 kJ mol−1). Besides, the linear driving force model (LDF) was used satisfactorily to describe the kinetic behavior of atrazine. Also, in treating a sample of river water contaminated with atrazine, Hd-AC showed high performance, reaching the removal of 70 % of the emerging pollutant. Therefore, using the residual fruits of the Hovenia dulcis as biomass to prepare a highly porous adsorbent reveals a promising alternative.