Solvent free mechanochemical synthesis of MnO2 for the efficient degradation of Rhodamine-B

Abstract

MnO 2 nanorods were synthesized by mechanochemical processing with subsequent heat treatment and their photocatalytic activity was studied on the decolourization of aqueous solution of Rhodamine B at different pH levels. A solid state redox reaction 2KMnO 4 + MnCl 2 → 3MnO 2 + 2KCl + O 2 was activated during mechanical milling. Excess KCl salt was added in the starting powder mixture to prevent agglomeration of MnO 2 nanoparticles. The milling resulted in the production of amorphous MnO 2 nanoparticles with a high surface area of 204 m 2 g -1 . Crystalline MnO 2 nanorods of diameters about 15 nm -20 nm were produced by heating the as-milled powder at 350°C for 1 hour in air. Amorphous MnO 2 nanoparticles showed higher degradation rate of Rhodamine B than crystalline MnO 2 nanorods under simulated sunlight. The degradation rate was higher under acidic conditions. This work demonstrates the potential for cost effective, green and scalable synthesis of MnO 2 nanocatalysts for environmental applications.

Preparation and characterization of MnO2-based nanoparticles at different annealing temperatures and their application in dye removal from water

“…The growing industrial development has facilitated human life but has equally posed constant threat for the human health as well as the environment because of enormous waste generation and discharge of wastewater effluents to aquatic environment (Fu et al 2015). The wastewater effluents from industries mainly from chemical industrial facilities, cosmetic, textile, leather, printing and paper industries contain significant amounts of toxic, carcinogenic and harmful substances including heavy metals, dyes and other chromophoric groups (Gagrani et al 2018;Shayesteh et al 2017). Due to presence of numerous dyes in water, the sunlight penetration is reduced causing irreparable damages in aquatic environment and the changes in taste and color of the waters is commonly observed (Siddiqui et al 2019).…”

One-pot mechanochemical ball milling synthesis of the MnOx nanostructures as efficient catalysts for CO2 hydrogenation reactions

“…[25][26][27][28] The mechanochemical synthesis is suitable for the large-scale production of a variety of nanomaterials and catalysts, [29][30][31][32][33] but a few reports in the literature have described the synthesis of manganese oxides via this process. [34][35][36][37] The mechanochemical synthesis can be tuned by many parameters such as the milling rotation speed, the milling time, the solvent-template, the weight ratios of the milling mixtures and milling balls, the milling atmosphere, the type of mills, and additional treatments such as sonication or heat treatments as well. [38][39][40][41][42][43] The conventional dry milling method has significant drawbacks such as wider size distribution of materials, material loss, and friction.…”

Facile synthesis of a high purity α-MnO2 nanorod for rapid degradation of Rhodamine B

“…7b and 7c), suggesting no generation of N-deethylated intermediates of RhB. It is well known that the surface charge of catalyst depends largely on the pH value of the solution [1,[30][31][32]. The pH PZC of α-MnO 2 nanorods is determined to be 3.08 (Fig.…”

“…Random discharge of dye wastewater from the textile industries will cause toxicological and aesthetic problems, reduce the photosynthetic activity of aquatic plants, and bring about adverse effects on aquatic organisms, human health and the environment due to high chemical oxygen demand, high intensity of color, hard to degrade, high toxicity and even potential carcinogenic risk [1][2][3][4][5]. Rhodamine B (RhB) is a water-soluble xanthene organic dye, which contains four N-ethyl groups at either side of the xanthene ring, and it is widely used in textile, printing, photography and other industries.…”