Poly(sodium 4-styrenesulfonate) brushes-functionalized UiO-66-NH2 metal-organic framework for high and selective adsorption of dyes
Advanced adsorbents with high adsorption capacity and adsorption selectivity are desirable. Here, a Zr-based metal-organic framework (MOF), UiO-66-NH 2 @poly(sodium 4-styrenesulfonate, Nass), was synthesized using the high surface area of MOFs as a substrate and the high grafting density of surface initiated-atom transfer radical polymerization (SI-ATRP). UiO-66-NH 2 @poly(Nass) was used to adsorb different dyes. The maximum adsorption capacity ( Q m ) of methylene blue (MB) and basic fuchsine (BF) was 299.8 and 789.2 mg·g −1 , respectively, which were higher than those of Sudan I (SD I, 6.340 mg·g −1 ), neutral red (NR, 188.1 mg·g −1 ), methyl orange (MO, 199.5 mg·g −1 ), and acid chrome blue K (AK, 122.3 mg·g −1 ). The adsorption isotherms and kinetics were investigated, and it was confirmed that the Langmuir isotherm and the pseudosecond-order kinetic model fit our adsorbents. In the binary mixed solution, the removal rate (R) of MB reached 64.44%, while that of MO was only 3.340% for MB/MO. R was 64.29% for MB and 21.97% for AK for MB/AK and 97.45% for BF and 30.03% for MO for BF/MO, verifying the preferential selectivity to adsorb basic dyes. The superior adsorption was ascribed to multiple interactions, including electrostatic interaction , hydrogen bonding , and π–π accumulation. In addition, the effect of grafting poly(Nass) on the pore size of UiO-66-NH 2 was studied. The excellent stability showed that the R dropped by less than 15.62% after five consecutive cycles. The UiO-66-NH 2 @poly(Nass) was applied in the determination of MB and BF in water, crucian carp, and green shrimp. Good linearity was observed for MB (R 2 = 0.9971) and BF (R 2 = 0.9993) in the range of 0.2–30 and 0.5–50 μg·mL -1 , respectively, with satisfactory recoveries (in the range of 87.45–101.3% for MB and 90.34–98.86% for BF), achieving favorable practicability.
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