Fig 1.
Schematic representation of the preparation of biochars from BSG, BSS and MIX.
Table 1.
Evaluation of the absorbent materials: Testing with concentrations of 20 mg/L and 50 mg/L Cr(VI) at pH 2.5, 2 g/L adsorbent, 24 h contact time, shaking at 200 rpm, and 25°C.
Table 2.
Results of the proximate analysis of the adsorbent samples.
Fig 2.
pHPZC determination for (A) BSG UT-1 and (B) BSG AT-5.
Fig 3.
FTIR spectra of the BSG AT-5 biochar before and after adsorption.
Fig 4.
XRD patterns of the BSG AT-5 biochar before and after Cr(VI) loading.
Fig 5.
SEM images of BSG AT-5 biochar before adsorption (A & C) at 300 & 600× magnification and after adsorption (B & D) at 300 & 600× magnification.
Fig 6.
A) PFO and PSO plots, B) Intraparticle diffusion model plot, C) Effect of initial pH on Cr(VI) adsorption, D) Effect of adsorbent dose on Cr(VI) adsorption.
Table 3.
Parameters of the PFO and PSO kinetic models and isotherm parameters for Cr(VI) removal by BSG AT-5 biochar.
Fig 7.
A) Effect of initial concentration on Cr(VI) adsorption, B) Langmuir and Freundlich isotherm model for the adsorption of Cr(VI) onto BSG AT-5 biochar, C) Effect of interfering ions on Cr(VI) removal, D) Adsorption‒desorption cycles for Cr(VI) removal by the BSG AT-5 biochar.
Table 4.
Comparison of the adsorption capacity of BSG biochar with that of previously reported adsorbents.