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

Abstract

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 H2nip= 5-nitroisophthalic acid) has been synthesized and characterized. In 1, the two carboxyl groups of each 5-nip2− ligand adopts μ2-η1:η1 and μ1-η1:η1 coordination fashion to connect ZnII 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, ∼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 O2·− 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.