Effectiveness and mechanisms of dye adsorption on a straw-based biochar.
A biochar (BC) generated from straw as a cost-effective substitute for activated carbon (AC) was tested for its adsorptive ability toward reactive brilliant blue (KNR) and rhodamine B (RB). BC and AC had similar surface areas but differed in porosity, surface acidity and point of zero surface charge. The two carbons were highly effective adsorbents for both dyes at pH 3.0 and 6.5. BC was slightly more effective than AC to adsorb RB due to the RB-BC electrostatic interactions and RB protonation at low pH. The two carbons reversed in their effectiveness to adsorb KNR for similar reasons. The pi-pi interactions between dye molecules and graphene layers of BC, the direct dye-BC electrostatic attraction/repulsion and the intermolecular hydrogen bonding are proposed to be the combined mechanisms for dye adsorption. Rich phenolic hydroxyls on the surface of BC are expected to enhance the pi-pi interactions.
Qiu
Yuping
Y
College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
Zheng
Zhenzhi
Z
Zhou
Zunlong
Z
Sheng
G Daniel
GD
D000327:Adsorption; D001557:Benzenesulfonates / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry; D002606:Charcoal / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D016062:Porosity; D012235:Rhodamines / Q000737:chemistry*; D013499:Surface Properties
D001557:Benzenesulfonates; D004396:Coloring Agents; D012235:Rhodamines; C540010:biochar; D002606:Charcoal; D002482:Cellulose; C006796:brilliant blue; C029773:rhodamine B