Efficient elimination of methyl violet 2B from wastewater using novel nanostructures

This is the authors' abstract. We don't add key points for this paper.

Methyl Violet 2B is a toxic cationic dye that can damage aquatic organisms and accumulate in the food chain and thus poses serious ecological risk even at low levels. Prolonged human exposure may cause organ damage and potential carcinogenic effects. Hence, in this work, SrCO 3 /MgMn 2 O 4 /C and Mg 6 MnO 8 /Sr 7 Mn 4 O 15 /Sr(OH) 2 .H 2 O/C hybrid nanostructures denoted MSM600 and MSM800, were obtained through the Pechini-derived sol–gel approach at 600 and 800 °C for Methyl Violet 2B elimination from wastewater. XRD verified the presence of highly crystalline multiphase oxide/carbon nanohybrids and showed that the average crystallite size increased from 58.11 nm concerning MSM600 to 74.47 nm concerning MSM800 because of stronger grain enlargement at higher temperature. EDX measurements showed C, O, Mg, Mn, and Sr in both samples and indicated enrichment in Mn and Sr and a lower C content for MSM800, which reflects more complete burnout of organic species. FE-SEM and HR-TEM images showed compact plate-like and rod-like particles built from nearly spherical nanograins in MSM600 and more elongated rod-like and fused aggregates in MSM800, which provide abundant accessible surface sites. Batch adsorption tests gave Langmuir maximum capacities of 444.44 mg/g regarding MSM600 as well as 342.47 mg/g regarding MSM800, and the process followed the pseudo-first-order kinetic model and the Langmuir isotherm and was exothermic, spontaneous, and physical. These capacities markedly exceed those reported for representative Methyl Violet 2B adsorbents, including activated carbon (134.10 mg/g), chitosan modified with walnut shell (103.30 mg/g), and halloysite nanotube/Fe 3 O 4 composite (20.04 mg/g), highlighting the competitive adsorption performance of the present nanocomposites. The nanohybrids were efficiently regenerated using acidic eluent and maintained high performance over several reuse cycles, and they also removed Methyl Violet 2B effectively from real laboratory wastewater, which highlights their promise for practical dye-contaminated effluent treatment.