Enhanced Photocatalytic Degradation of Malachite Green Dye Using Silver-Manganese Oxide Nanoparticles.

Efficient and excellent nanoparticles are required for the degradation of organic dyes in photocatalysis. In this study, silver-manganese oxide nanoparticles (Ag-Mn-NPs) were synthesized through a wet chemical precipitation method and characterized as an advanced catalyst that has enhanced photocatalytic activity under sunlight irradiation. The nanoparticles were characterized using scanning electron microscopy (SEM), XRD, UV-vis light spectra, and energy-dispersive X-ray (EDX) spectroscopy, revealing their spherical and agglomerated form. The EDX spectra confirmed the composition of the nanoparticles, indicating their presence in oxide form. These bimetallic oxide nanoparticles were employed as photocatalysts for the degradation of malachite green (MG) dye under sunlight irradiation in an aqueous medium. The study investigated the effects of various parameters, such as irradiation time, catalyst dosage, recovered catalyst dosage, dye concentration, and pH, on the dye's photodegradation. The results showed that Ag-Mn oxide nanoparticles exhibited high photocatalytic activity, degrading 92% of the dye in 100 min. A longer irradiation time led to increased dye degradation. Moreover, a higher catalyst dosage resulted in a higher dye degradation percentage, with 91% degradation achieved using 0.0017 g of the photocatalyst in 60 min. Increasing the pH of the medium also enhanced the dye degradation, with 99% degradation achieved at pH 10 in 60 min. However, the photodegradation rate decreased with increasing dye concentration. The Ag-Mn oxide nanoparticles demonstrate excellent potential as a reliable visible-light-responsive photocatalyst for the efficient degradation of organic pollutants in wastewater treatment.

A comprehensive review on pollution status and associated health risk assessment of human exposure to selected heavy metals in road dust across different cities of the world.

In order to expound on the present situation and potential risk of road dust heavy metals in major cities, a total of 114 literatures mainly over the past two decades, involving more than 5000 sampling sites in 61 cities of 21 countries, were screened through the collection and analysis of research papers. The concentration, sources, distribution, health risk, sample collection, and analytical methods of heavy metal research on road dust in cities around the world are summarized. The results show that Cd, Zn, and Cu in many urban road dusts in the world are higher than the grade II of the Chinese maximum allowable concentration of potentially toxic elements in the soil. Geo-accumulation index values show that Pb > Cd > Zn > Cu had the highest contamination levels. Hazard index assessment indicates Pb and Cr had the highest potential health risk, especially for children in which ingestion was found as the main exposure pathway. Moreover, through comparative analysis, it is found that some pollutants are higher in developed and industrialized cities and transport (53%) followed by industrial emissions (35%) provide the major contributions to the sources of heavy metals.

A critical analysis of sources, pollution, and remediation of selenium, an emerging contaminant.

Selenium (Se) is an essential metalloid and is categorized as emerging anthropogenic contaminant released to the environment. The rise of Se release into the environment has raised concern about its bioaccumulation, toxicity, and potential to cause serious damages to aquatic and terrestrial ecosystem. Therefore, it is extremely important to monitor Se level in environment on a regular basis. Understanding Se release, anthropogenic sources, and environmental behavior is critical for developing an effective Se containment strategy. The ongoing efforts of Se remediation have mostly emphasized monitoring and remediation as an independent topics of research. However, our paper has integrated both by explaining the attributes of monitoring on effective scale followed by a candid review of widespread technological options available with specific focus on Se removal from environmental media. Another novel approach demonstrated in the article is the presentation of an overwhelming evidence of limitations that various researchers are confronted with to overcome achieving effective remediation. Furthermore, we followed a holistic approach to discuss ways to remediate Se for cleaner environment especially related to introducing weak magnetic field for ZVI reactivity enhancement. We linked this phenomenal process to electrokinetics and presented convincing facts in support of Se remediation, which has led to emerge 'membrane technology', as another viable option for remediation. Hence, an interesting, innovative and future oriented review is presented, which will undoubtedly seek attention from global researchers.

Enhancement of photocatalytic potential and recoverability of Fe3O4 nanoparticles by decorating over monoclinic zirconia.

BACKGROUND: Photodegradation of organic pollutants is considered to be the most suitable and cheaper technique to counter the decontamination issues. Metal nanoparticles are considered to be the most effective heterogeneous photocatalysts for photodegradation of organic pollutants. Besides, iron oxide nanoparticles are well-known photocatalysts for degrading organic pollutants. METHODS: We reported the synthesis of neat iron oxide nanoparticles (Fe3O4 NPs) and zirconia supported iron oxide nanoparticles (Fe3O4/ZrO2 NPs) by facile chemical reduction technique for photodegradation ofa toxic azo dye namely methyl red. RESULTS: The XRD and FTIR analysis has demonstrated a crystalline phase Fe3O4 NPs. The morphological features via scanning electronic microscopy (FESEM) suggested agglomerated morphology of neat Fe3O4 NPs with 803.54 ± 5.11 nm average particle size and revealed the uniform morphology and homogenous dispersion of Fe3O4 NPs over ZrO2 surface in Fe3O4/ZrO2 nanocomposite. A polydispersity index (PDI) of 0.47 showed sufficient variations in the particle size of neat Fe3O4 NPs, which is also supported by the results obtained from atomic force microscopy (AFM), FESEM and Transmission Electron Microscopy (TEM). Fe3O4/ZrO2 NPs demonstrated efficient methyl red degradation over a short period of time under simulated light and degraded about ~ 91.0 ± 1.0% and 87.0 ± 1.0% dye in 40 min, under UV and visible light, respectively. CONCLUSION: The excellent photodegradation efficacy and sustainability of Fe3O4/ZrO2 NPs can be attributed to the homogenous distribution of Fe3O4 NPs over ZrO2, which facilitates the generation of photoexcitons (electrons and holes), enhanced charge transfer and minimize the charge recombination.