Abstract
It is well-known that chitosan consists of amino groups for the chelation of metal ions while NH2-MCM-41 has excellent adsorption selectivities for metals. This work compares both adsorption capacities and selectivities of chitosan and NH2-MCM-41. It has been found that chitosan has adsorption capacities of 1.76mmol/g, 1.03mmol/g and 1.30mmol/g for Cu2+, Ni2+ and Zn2+ respectively whereas NH2-MCM-41 has adsorption capacity of 1.52mmol/g, 0.8mmol/g and 0.83mmol/g for Cu2+, Ni2+ and Zn2+. The higher adsorption capacity in chitosan is attributed to its higher loading of amine groups. The single component adsorption isotherms were well-fitted using Freundlich model. The binary adsorptions of Cu2+-Zn2+ and Ni2+-Zn2+ systems showed similar adsorption selectivities for both adsorbents. However, chitosan has no preferential adsorption for Ni2+-Zn2+ system while NH2-MCM-41 has a good selectivity towards Zn2+. It is believed that the difference can be attributed to the heterogeneous surface of chitosan due to its organic nature. The multi-component adsorptions were best described by a multicomponent extended Freundlich model. Despite the surface functional group, this work indicates the importance of the adsorbent support on selective adsorption.
Original language | English |
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Pages (from-to) | 230-240 |
Number of pages | 11 |
Journal | Journal of Colloid and Interface Science |
Volume | 395 |
Issue number | 1 |
DOIs | |
Publication status | Published - 1 Apr 2013 |
Externally published | Yes |
Keywords
- Adsorption
- Chitosan
- MCM-41
- Mesoporous silica
- Selectivity