Study on the adsorption of dyestuffs with different properties by sludge-rice husk biochar: Adsorption capacity, isotherm, kinetic, thermodynamics and mechanism

Publication date: 1 July 2019Source: Journal of Molecular Liquids, Volume 285Author(s): Si Chen, Chaoxian Qin, Teng Wang, Fangyuan Chen, Xuli Li, Haobo Hou, Min ZhouAbstractThe adsorption capacity, isotherm, kinetics, thermodynamics and mechanism of four dyes with different properties on a novel economical sludge-rice husk biochar (SRHB) were determined. The sludge and rice husk with ratio of 1:1 were pyrolyzed at 500 °C, for 2 h in a tubular furnace. The SRHB was characterized using an element analyzer, Brunauer-Emmett-Teller (BET) method, X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential measurement and X-ray photoelectron spectroscopy. Results of the adsorption experiments revealed that the adsorption capacities of these dyes on the SRHB followed the order: Direct Red 4BS (DR) > Acid Orange II (AO) > React Blue 19 (RB) > Methylene Blue (MB). Adsorption data of DR, RB, AO, MB all fitted both the Langmuir isotherm and Freundlich isotherm well, Temkin and D-R isotherm models verified the result. Kinetic data of the four dyes showed good correlation with the pseudo-second-order model. The adsorption of DR and AO onto SRHB were exothermic, while that of RB and MB were endothermic. Dyestuffs sorption on the SRHB involved surface participation, electrostatic interaction, π-π interactions, hydrogen bond. However the main adsorption mechanisms of the different dyes onto the SRHB varied. Therefore, the SRHB could be an effective adsorbent ...
Source: Journal of Molecular Liquids - Category: Molecular Biology Source Type: research