Cr(III) adsorption by sugarcane pulp residue and biochar

YANG Zhi-hui(杨志辉)¹, XIONG Shan(熊珊)¹, WANG Bing(王兵)^{1, 2}, LI Qian(李倩)¹, YANG Wei-chun(杨卫春)¹

(1. National Engineering Research Center for Pollution Control of Heavy Metals,
School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China;
2. Environme)

Abstract:A batch experiment was conducted to investigate the adsorption of trivalent chromium (Cr(III)) from aqueous solutions by sugarcane pulp residue (SPR) and biochar. The results show that Cr(III) adsorption by SPR and biochar is highly pH-dependent and Cr(III) adsorption amount increases with the increase of pH. The adsorption kinetics of Cr(III) fits well with the pseudo-second-order model. The maximum Cr(III) adsorption capacities of 15.85 mg/g and 3.43 mg/g for biochar and SPR were calculated by Langmuir model. This indicates that biochar has a larger ability for Cr(III) adsorption than SPR. The free energy change value (ΔG) reveals a spontaneous sorption process of Cr(III) onto SPR and non-spontaneous sorption process onto biochar. The entropy change (ΔS) and enthalpy change (ΔH) are found to be 66.27 J/(mol?K) and 17.13 kJ/mol for SPR and 91.59 J/(mol?K) and 30.875 kJ/mol for biochar which further reflect an affinity of Cr(III) onto SPR and biochar. It is suggested that biochar has potential to be an efficient adsorbent in the removal of Cr(III) from industrial wastewater.

Key words:Cr(III); adsorption; sugarcane residue pulp; biochar