(746j) Removal of Mixture of Dyes Using Water Stable Metal Organic Framework

Metal Organic Frameworks (MOFs) are advanced materials finding diverse applications in several areas including catalysis[1], wastewater treatment[2], sensing[3], etc. Owing to their high capacity, these materials may be effectively used in the removal of dyes from aqueous streams. MOFs are three dimensional networked compounds consisting of metal centres and linkers. The metal centre, along with their coordinated groups, constitutes the secondary building unit (SBU). These SBUs hold the 3 dimensional network and the linkers form the bridge between different SBUs in a unit cell. The MOF under investigation viz. MIL-101(Cr) is chromium centred and consists of the linker terephthalic acid. This MOF synthesis was intensified using an optimized solvothermal procedure. The XRD, BET and FTIR studies revealed that the MOF produced was similar to the one synthesized solvothermally by S. Karmakar et al [4]. The results will be presented.

The MOF synthesized was used for adsorption of sunset yellow and coomasie brilliant blue g250 from aqueous solutions. These dyes are the pollutants obtained from household as well as textile industry. They are found to be anionic in nature as they have SO₃^- functional groups and are found to have low pK_a values and, hence, will exist in aqueous solution as anionic and thus the operation of pH was maintained from 3 to 7 because beyond pH of 8 the MOF was found to be unstable as the carboxylate groups present in the linker got dissociated.

Preliminary adsorption studies were performed and it was found that the MOF was quite significantly removing the dyes from the aqueous stream but was found to take 3 days to equilibrate, thus, it was planned to alter the linker to improve the adsorption kinetics by adding functional groups.

[1] J. Liu, L. Chen, H. Cui, J. Zhang, L. Zhang, and C. Y. Su, “Applications of metal-organic frameworks in heterogeneous supramolecular catalysis,” Chemical Society Reviews, vol. 43, no. 16. Royal Society of Chemistry, pp. 6011–6061, Aug. 21, 2014, doi: 10.1039/c4cs00094c.

[2] J. Canivet, A. Fateeva, Y. Guo, B. Coasne, and D. Farrusseng, “Water adsorption in MOFs: Fundamentals and applications,” Chemical Society Reviews, vol. 43, no. 16. Royal Society of Chemistry, pp. 5594–5617, Aug. 21, 2014, doi: 10.1039/c4cs00078a.

[3] L. Huang, H. Wang, J. Chen, Z. Wang, and J. Sun, “Synthesis, morphology control, and properties of porous metal–organic coordination polymers,” Microporous Mesoporous Mater., 2003, Accessed: Apr. 30, 2018. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S1387181102006091.

[4] S. Karmakar, D. Roy, C. Janiak, and S. De, “Insights into multi-component adsorption of reactive dyes on MIL-101-Cr metal organic framework: Experimental and modeling approach,” Sep. Purif. Technol., vol. 215, no. October 2018, pp. 259–275, 2019, doi: 10.1016/j.seppur.2019.01.013.