Effects of Biochars Prepared from Cassava Dregs on Sorption Behavior of Ciprofloxacin

Abstract

Biochar is a carbon-rich solid material derived from biomass partial combustion under oxygen-limited condition. It plays a crucial role in affecting environmental fates of pollutants. In this paper, three biochars were produced from cassava dregs by the pyrolysis at different temperatures (350 ̊C, 550 ̊C, 750 ̊C), which were recognized as BC350, BC550 and BC750, respectively. And the character of biochars was compared using Elemental Analysis, Specific Surface Areas, Scanning Electronic Microscope and Fourier Transform Infrared Spectra. Batch equilibrium method was conducted to investigate the sorption of ciprofloxacin on biochars. The results were shown that: (1) biochars pyrolyzed at higher temperature had larger specific area and more mircopore volumes. (2) The kinetics of ciprofloxacin on biochars reached equilibrium after 24 h, which was included three steps, i.e., fast, slow and equilibrium reaction process. It showed that the kinetics was better fitted by pseudo second order kinetics equation than Elovich, intraparticle diffusion model with the correlation coefficient of 0.996-1.000. (3) Three biochars had strong sorption capacity for ciprofloxacin. The sorption process was well fitted by Freundlich model and Langmuir model. (4) Thermodynamic analysis were revealed the feasibility and spontaneity of the ciprofloxacin sorption process. (5) Sorption behavior of antibiotics on biochars was a consistently hysteretic and irreversible process.