The removal of methylene blue (MB) as a cationic dye from aqueous solution by the stabilized Fe(3)O(4) nano-particles with the extracted pectin from apple waste (FN-PA) increased due to using the cross-linked forms of the bound pectin on the nano-particles surface by glutaraldehyde (FN-PAG) and adipic acid (FN-PAA) as the cross-linking agents. This increase happened in spite of binding some of the adsorbent functional groups of pectin with nano-particles. It can be due to the local concentrate of other free functional groups after connecting with nano-scale particles. Thermodynamic studies showed that the adsorption equilibrium constant and the maximum adsorption capacities increased with increasing temperature for all of the nano-bioparticles. The kinetic followed the second-order models with the highest rate constants viz. 16.23, 19.76 and 23.04 (× 10(-3)g/mg min) by FN-PAA. The adsorption force arrangement of MB by these nano-biosorbents regarding their activation energy was obtained as: FN-PAA>FN-PAG>FN-PA.
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