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Adsorption characteristics of Direct Red 23 from aqueous solution by biochar.
- Source :
-
Journal of Molecular Liquids . Nov2016, Vol. 223, p335-342. 8p. - Publication Year :
- 2016
-
Abstract
- Biochar, produced by the pyrolysis of pig manure at 800 °C, was characterized and investigated as an adsorbent for the removal of Direct Red 23 from aqueous solution. The adsorption kinetics was best described by a modified Freundlich model and intra-particle diffusion models. The value of the apparent adsorption constant k (modified Freundlich model) decreased from 0.133 to 0.076 L/(g·min 1/m ), when the amount of biochar increased from 1 to 8 g/L. Values of effective particle diffusion coefficient (D p ) and liquid film diffusion coefficient (D f ) were calculated to further determine the rate-limiting step of the adsorption process. The value of activation energy 5.558 kcal/mol indicates that the adsorption is a physical process controlled by film diffusion and the adsorption process is endothermic. When pH < pH ZPC (8.71),the surface of biochar is positively charged; the positive charge promoted the anionic dyes attracted onto the biochar by electrostatic force; and a hydrogen band was formed with the protonated OH functional groups on the active sites. The adsorption equilibrium study indicates that the adsorption was in a multilayer mode, and the maximum adsorption capacity was 2.19 × 10 − 5 mol/g, at pH 2.20 and temperature 25 °C. Considering the widely availability and high removal efficiency, biochar is deserved further investigations for applications in more hazardous substances removal. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 01677322
- Volume :
- 223
- Database :
- Academic Search Index
- Journal :
- Journal of Molecular Liquids
- Publication Type :
- Academic Journal
- Accession number :
- 119000725
- Full Text :
- https://doi.org/10.1016/j.molliq.2016.08.061