Copper nickel co-impregnation of Moroccan yellow clay as promising catalysts for the catalytic wet peroxide oxidation of caffeine

Enhanced leachate concentrate degradation across variable pH ranges using Cu@ATP-CTS Fenton-like catalysts for H₂O₂ activation

Landfill leachate nanofiltration concentrates (LLNC) contain complex organic pollutants that are difficult to treat. This study developed a copper-doped attapulgite-chitosan composite catalyst (Cu@ATP-CTS) for efficient LLNC degradation in a Fenton-like system. The incorporation of attapulgite extended the effective pH range of Fenton reactions from 2 to 8, overcoming traditional limitations. Optimized via response surface methodology, the catalyst achieved 89.02% UV254 removal, 73.86% COD removal, and 77.24% TOC removal within 115 min under optimal conditions. Copper played a crucial role in H₂O₂ activation, cycling between Cu0, Cu+, and Cu2+ to generate hydroxyl radicals (·OH), the key species driving pollutant degradation. The Cu@ATP-CTS catalyst also demonstrated strong stability and reusability over five cycles. This study provides a robust and sustainable method for LLNC treatment, offering significant potential for application in landfill leachate and wastewater management.

Synthesis, characterization, and photocatalytic activities of green sol-gel ZnO nanoparticles using Abelmoschus esculentus and Salvia officinalis: A comparative study versus co-precipitation-synthesized nanoparticles

Background

The development of green chemistry methods involving plant-based nanoparticle synthesis presents an affordable and eco-friendly approach for wastewater treatment and color removal. This study aimed to synthesize ZnO nanoparticles using the sol-gel method with Salvia officinalis and Abelmoschus esculentus plants, examining their photocatalytic efficiency for organic dye removal.

Methods

To compare the properties of ZnO nanoparticles, another type of ZnO-NPs was synthesized using the co-precipitation method. The characterization of synthesized nanoparticles was performed using thermogravimetric analysis (TGA-DTG), X-ray diffraction (XRD), Dynamic Light Scattering (DLS), Zeta potential (ZP), field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), and UV-Vis spectrophotometry.

Results

Based on XRD results, the average crystalline size of nanoparticles was calculated using the Debye-Scherer equation for synthesized nanoparticles using the S. officinalis at 22.99 nm and for the A. esculentus at 29.79 nm, and for the co-precipitation method at 18.83 nm. The FE-SEM images showed spherical ZnO nanoparticles. Photocatalytic properties of ZnO-NPs were investigated for remove of methylene blue organic dye in the presence of UV light. The pH 10 was identified as the best pH, which had the highest percentage of color degradation. All three types of nanoparticles were tested by up to 360 min to optimize the dyeing time. For A. esculentus, the highest percentage of color removal occurred in the first 90 min (41.0 %), for S. officinalis nanoparticles between 75 and 90 min (86.9 %), and for chemically synthesized nanoparticles between 30 and 45 min (100 %).

Conclusions

In conclusion, the best MB dye degradation capacity belonged to co-precipitation ZnO nanoparticles followed by S. officinalis and A. esculentus nanoparticles.