One-pot preparation of MnO impregnated cotton fibers for methylene blue dye removal

• Published in: RSC advances 2018-06, Vol.8 (38), p.21577-21584
• Main Authors: Wang, Jing, Kou, Lidong, Huang, Zuohua, Zhao, Liang
• Format: Article
• ISSN: 2046-2069
• DOI: 10.1039/c8ra03924k

Using natural cotton fibers (CF) as a matrix, a series of novel MnO x impregnated cotton fibers (designated as Mn- X @BCF) were prepared in this study through a one-pot sono-assisted KMnO 4 reduction process with no additional reducers. The as-prepared Mn- X @BCF was covered by a uniform and dense layer of MnO x nanospheres (10-30 nm), the amount of which was significantly improved by CF pretreatment and linearly correlated with KMnO 4 concentration. Specifically, when KMnO 4 concentrations increased from 5 mmol L −1 to 100 mmol L −1 , the impregnation ratios of MnO x on BCF increased from 0.34% to 14.98% accordingly. Mn- X @BCF showed substantial removal for the typical dye MB. Under the studied conditions, MB removal equilibrium was reached within 10 minutes and solution pH showed no significant influence over a wide pH range (2-11). MB adsorption by Mn-25@BCF obeyed the pseudo-second-order kinetic model and Langmuir model well. The calculated maximum adsorption capacity ( Q m ) of Mn-25@BCF was 46.3 mg g −1 , close to the cumulative adsorption capacity ( Q c 45 mg g −1 ) of MB determined during the eight cycles of adsorption. It was proposed that adsorption followed by partial oxidation was the main mechanism of MB removal by Mn- X @BCF. The as-prepared Mn-25@BCF has great potential as an efficient and low-cost material for dye wastewater treatment because of its inexpensive and renewable source of raw materials, fast MB removal kinetics, wide working pH range and easy solid-liquid separation. Mn- X @BCF, prepared by one-pot sono-assisted KMnO 4 reduction, could remove methylene blue efficiently by a proposed adsorption-partial oxidation mechanism.