XU Yanli, YANG Hanbiao, LÜ Mengmeng, et al. Effects of various factors on adsorption of MIL-101(Cr) for dyes in aqueous solutions[J]. CIESC Journal, 2015, (10): 4025-4031.
XU Yanli, YANG Hanbiao, LÜ Mengmeng, et al. Effects of various factors on adsorption of MIL-101(Cr) for dyes in aqueous solutions[J]. CIESC Journal, 2015, (10): 4025-4031.DOI: 10.11949/j.issn.0438-1157.20140942.
the adsorption capacity of metal-organic framework
MIL-101(Cr)
was measured for cationic dyes (methylene blue (MB)
rhodamine B) and anionic dyes (helianthine B (HB)
acid chrome blue K) in aqueous solutions. The effect of various factors on the adsorption selectivity of MIL-101(Cr) was studied for HB and MB in mixed solutions. The results show that the adsorption capacity to anionic dyes is higher than that to cationic dyes when the dyes exist solely or coexist. The selection coefficient b is 5.9 at T=300 K and pH=3
and it decreases obviously with the increase of pH value
while temperature has a little effect on adsorption selectivity. The mechanism for adsorption selectivity is that MIL-101(Cr) has positive surface potential
so there exist electrostatic attractive interactions between MIL-101(Cr) and anionic dye molecules while it is repulsion interaction for cationic dyes. Moreover
modification with ethyl diamine increases the adsorption selectivity of MIL-101(Cr) for anionic dyes
whereas with oxalic acid the selectivity decreases.