# Green-Synthesized Nanomaterials for Catalytic Reduction of para-Nitrophenol and Methylene Blue: Recent Advances and Perspectives

## TL;DR

This paper reviews green-synthesized nanomaterials for efficiently reducing harmful pollutants like para-nitrophenol and methylene blue in wastewater.

## Contribution

The paper systematically reviews green-synthesized nanomaterials for catalytic reduction, emphasizing their alignment with sustainability goals.

## Key findings

- Green-synthesized nanomaterials show high efficiency in reducing para-nitrophenol and methylene blue.
- Comparative analysis highlights the impact of precursors and conditions on catalytic efficiency and reusability.
- The approach avoids toxic by-products and aligns with circular economy principles.

## Abstract

Nitrophenol (NP) and methylene blue (MB) are considered among the most hazardous organic contaminants frequently released from pharmaceutical, textile, and paper industries, posing significant risks to both human health and the environment. The conventional treatment involves adsorption, oxidation, biological, filtration, and other photochemical degradation methods, which often suffer from low efficiency, limited reusability, and the production of secondary toxic by-products. In this context, the nanomaterials (NMs) mediated catalytic reduction of MB into leucomethylene blue and p-NP into p-aminophenol (p-AP) has emerged as a promising approach, due to its high efficiency and effectiveness. This review emphasizes the green synthesis of NMs for catalytic applications, which align with the principles of the circular economy and the Sustainable Development Goals (SDGs). This thorough review systematically examines the mechanistic understanding of the reduction of both p-NP and MB via different green synthesized NMs and evaluating their catalytic efficiencies. Furthermore, a detailed discussion of the reduction of pollutants (p-NP and MB) is provided, along with their mechanistic insights. In addition, this paper also provides a comparative table highlighting the effects of using different precursors, experimental conditions on the conversion catalytic efficiency and reusability potency. Thus, this work provides the insights into recent research on the catalytic reduction of p-NP and MB into valuable products, highlighting the significance of green synthesized nanocatalysts for effective wastewater treatment.