Effect of production temperature in biochar properties from bamboo culm and its influences on atrazine adsorption from aqueous systems

Abstract

Biochar from bamboo culm was produced at three different temperatures (350, 450 and 550 °C) and evaluated concerning the effect of biochar production temperature on atrazine adsorption. The biochars were characterized by elemental composition, point of zero charge (pHpzc), N2 physisorption, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) Spectroscopy. Adsorption experiments were performed in a batch mixer. Kinetic and equilibrium experimental data were obtained for the three biochars. The elemental composition and FTIR analysis indicated enhanced aromaticity of the biochar as the production temperature increased. The N2 physisorption and SEM analysis of the biochars showed an increase in the porosity and specific surface area as the production temperature increased, which can favor the atrazine adsorption process. The experimental equilibrium data were well described by the Langmuir isotherm. The biochar produced at 450 °C presented the highest atrazine experimental adsorption capacity, which may be related to the micro-mesopore ratio and surface area exhibited by this biochar. From the kinetic data, similar equilibrium times for the three biochars were achieved. To describe the kinetic adsorption data for the biochars, phenomenological models based on adsorption on the adsorbent surface, external diffusion and internal diffusion were applied, in which the internal diffusion model presented the best fit of the experimental data for all biochars. The results showed the influence of temperature production on the biochars properties and displayed its effects in the removal efficiency of atrazine from water, wherein the biochar produced at 450 °C presented the best performance for atrazine adsorption.