Synthesis of an efficient MOF catalyst for the degradation of OPDs using TPA derived from PET waste bottles

Sustainable conversion of polyethylene plastic bottles into terephthalic acid, synthesis of coated MIL-101 metal-organic framework and catalytic degradation of pollutant dyes

Persistent environmental colored compounds, resistant to biodegradation, accumulate and harm eco-systems. Developing effective methods to break down these pollutants is crucial. This study introduces Ag-MIL-101 (Ag-MIL-101) as a composite and reusable catalyst that efficiently degrades specific colored organic pollutants (COPs) like Methylene blue (MB), 4-Nitrophenol (4-NP), and 4-Nitroaniline (4-NA) using sodium borohydride at room temperature. The MIL-101 was synthesized using Terephthalic acid (TPA) derived from the degradation of Polyethylene Terephthalate (PET) plastic waste, with the assistance of zinc chloride. To further investigation, the kinetics of degradation reaction was studied under optimized conditions in the presence of Ag-MIL-101 as catalyst. Our results demonstrated the remarkable efficiency of the degradation process, with over 93% degradation achieved within just 8 min. The catalyst was characterized using FTIR, XRD, FESEM, and TEM. In this study, the average particle size of Ag-MIL-101 was determined using SEM and XRD analysis. These methods allow us to accurately and precisely determine the particle size. We determined the reaction rate constants for the degradation of each COP using a pseudo first-order kinetic equation, with values of 0.585, 0.597 and 0.302 min-1 for MB, 4-NP, and 4-NA, respectively. We also evaluated the recyclability of the catalyst and found that it could be reused for up to three cycles with only a slight decrease in efficiency (10-15%). Overall, our findings highlight the promising application of Ag-MIL-101 as an effective catalyst for the degradation of COPs, emphasizing the importance of optimizing reaction conditions to achieve enhanced efficiency.

In situ and bio-green synthesis of silver nanoparticles immobilized on zeolite as a recyclable catalyst for the degradation of OPDs

In this study, silver nanoparticles (Ag-NPs) were synthesized using a green and biologically inspired approach by utilizing reducing compounds from Thyme plant leaves. Zeolite was used to immobilize the synthesized Ag-NPs (Ag@Z). The modified Zeolite served as a catalyst for the reduction reaction of various organic pollutant dyes (OPDs) including 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), methylene blue (MB), and methyl orange (MO) with sodium borohydride. The degradation of OPDs was monitored by measuring changes in their maximum absorption wavelength intensity. A thorough examination of multiple parameters (catalyst, silver and sodium borohydride dosage, yield degradation, and reaction time) was carried out to identify the optimized conditions for the degradation of OPDs. The results showed that the Ag@Z catalyst achieved an efficiency of over 93% in less than 10 min for the degradation of OPDs. The recoverability and reusability of the catalyst were examined, revealing a partial loss in efficiency after four recovery stages. Structural analysis using XRD, SEM, and TEM techniques confirmed the characteristics and morphology of the synthesized catalyst.