A new 2D Zn(II)-based coordination polymer as photocatalyst for photodegradation of methyl orange in water: Effect of photocatalyst dosage and dye concentration

The metal-organic frameworks (MOFs) a sub-class of well-known coordination polymer are assorted multidimensional materials that could be employed as photocatalysts for dye decomposition present in the wastewater discharge. Herein, a new Zn(II)-based coordination polymer with formula [Zn(bpyp)(5-nip)] (1) (bpyp = 2,5-bis (pyrid-4-yl)pyridine and H(2)nip= 5-nitroisophthalic acid) has been synthesized and characterized. In 1, the two carboxyl groups of each 5-nip(2-) ligand adopts mu(2)-eta(1):eta(1) and mu(1)-eta(1):eta(1) coordination fashion to connect Zn-II centers into a 1D chain along b direction, which alternately contains 8-membered rings and 16-membered rings. The newly synthesized compounds have been used as the photocatalyst for the photodegradation of methyl blue (MB), methyl orange (MO), rhodamine B (RhB) and methyl violet (MV) dyes under UV light irradiation. The results reveal that amongst all four dyes, 1 decomposes MO dye to maximum extent. The effects of concentration of dyes, and photocatalyst dosages have been monitored on the photocatalytic performance of 1. Under the optimal reaction condition, similar to 89.03% photodegradation of MO has been observed at 20 ppm concentration of MO and 20 mg photocatalyst concentration in 50 min time span. The radical trapping experiments suggest that O-2(center dot-) is the main active species that catalyzes the photodecomposition of dyes. The possible mechanism for the MO degradation of 1 is proposed using density of states (DOS) calculations and Hirshfeld surface analysis.