Synthesis of green catalyst laponite / molybdate composite as an environmental dye removal.

Abstract

The current invention describes the synthesis of heterogeneous composite comprising laponite and heptamolybdate by wetness impregnation method. Different experimental settings were used to carry out the synthesis, including the heptamolybdate ammonium dose (1.5, 1 or 0.5 g), ion exchanger dose tetrabutyl ammonium bromide (0.5, 0.25 or 0.125g), reaction duration (12 or 24h) and calcination temperature (200, 300 and 400 °C) for 2 hours. The optimal synthesis composition of the laponite / molybdate (Lap-Mo) is as follows: 5 g of Lap + 0.5 g of TBA + 1.5 g of heptamolybdate ammonium with reaction duration of 24 h and a calcination temperature of 300 °C for 2 hours under air. The laponite / molybdate composite have been used in an AOP to degrade MB dye in presence of H2O2 as an oxidant under visible light radiation. The AOP experiment have been optimized using RSM based on BBD. Under the optimum conditions: contact time=72 min, [H2O2 / Lap-Mo] wt% ratio= 1.24, dye concentration= 20.95 mg.L-1 pH= 8.3 reaching a 99% of degradation rate. The Lap-Mo catalyst degradation efficiency was also tested for other dyes such as safranin T (ST) and rhodamine B (RhB) as cationic dyes and methyl orange (MO) as anionic dye. Indeed, they exhibits a highly degradation rate equal to 96, 90 and 89% for ST, RhB and MO, respectively. Advantageously, the invention intends to promote, profitably, and efficiently dye degradation using the laponite / molybdate composite. Furthermore, the potential of the invention falls within the framework of improving wastewater treatment and paves the way to more areas of application in multiple industries.