Tailoring CdSe nanoparticles at different pH levels for improved methylene blue photodegradation.

Synthesis of CdSe nanoparticles using a precipitation method, exploring the effects of varying pH levels of precursor concentrations. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), UV-Vis absorption spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR). XRD analysis revealed that the crystallite size ranged from 3 to 5 nm, with an increase in size corresponding to higher pH values. TEM images showed agglomerated spherical particles with sizes varying between 3 and 15 nm. The CdSe quantum dots, synthesized using the precipitation method with polyethylene glycol (PEG) as a surfactant, were chosen for photocatalytic activity studies due to their small size and high surface area-to-volume ratio, which enables efficient photon absorption. The photocatalytic process was conducted under visible light for 180 min, using an aqueous solution of methylene blue (MB) as the model pollutant. The results showed a high degradation efficiency of 91%, indicating that the synthesized CdSe nanoparticles are effective photocatalysts. Reusability tests carried out for three consecutive cycles demonstrated that the CdSe nanoparticles retained good photocatalytic activity with only a slight decline after repeated use. The novelty of this work lies in correlating pH-dependent precipitation synthesis with enhanced photocatalytic activity and reusability, underscoring the potential of CdSe quantum dots as efficient, economical, and stable photocatalysts for wastewater treatment and related environmental applications.