Mesoporous ferromagnetic manganese ferrite nanoparticles for enhanced visible light mineralization of azoic dye into nontoxic by-products.

In this study, a one pot facile synthesis of ferromagnetic manganese ferrite nanoparticles (MnFe2O4) was carried out using chemical co-precipitation method for mineralization of azo dye (Congo red (CR)) in aqueous solution under visible light irradiation. The synthesized MnFe2O4 nanoparticles were highly crystalline and showed face-centred cubic (FCC) structure with average particle size of 58 ± 4 nm. The BET analysis of the MnFe2O4 nanoparticles revealed the mesoporous distribution of material with high surface area can provide large electro active sites and short diffusion paths for the transport of ions which plays a vital role in the photocatalytic degradation of CR. The point of zero charge (pHPZC) was observed to be 6.7 indicating favourable condition for material-anionic dye interaction. The XPS studies revealed that the large amounts of oxygen vacancies were produced due to the defects in the lattice oxygen. The MnFe2O4 nanoparticles mineralised 98.3 ± 0.2% of 50 mg/L CR within 30 min when tested in photocatalytic reactor under 565 nm. The particles were recoverable under the influence of an external magnet after the photocatalytic reaction and were reusable. The recovered nanoparticles showed 96% of CR degradation efficiency even after five cycles of reuse. The by-product analysis with GC-MS indicated mineralization of CR into simple alcohols and acids. The aqueous solution containing mineralised CR was nontoxic to Trigonella foenumgraecum and Vigna mungo seeds and favoured increased germination, plumule and radicle length when compared to untreated CR.

One pot facile green synthesis of crystalline bio-ZrO2 nanoparticles using Acinetobacter sp. KCSI1 under room temperature.

In this study, crystalline ZrO2 nanoparticles were synthesized in one pot at room temperature using an extremophilic Acinetobacter sp. KCSI1 and characterized using various techniques to study its structural, optical and crystalline properties. The average size of the ZrO2 nanoparticles was found to be 44 ±â€¯7 nm. The XRD and Raman spectra showed the crystalline structure of ZrO2. HRTEM and SAED images showed well aligned ordered crystal lattice nanoparticles. The zeta potential of Bio-NP of ZrO2 has been found to be 36.5 ±â€¯5.46 mV. The mechanical behaviour such as hardness and Young's modulus of Bio-ZrO2 NPs were determined using atomic force microscopy (AFM) and found to be 9.206 ±â€¯2.22 and 0.285 ±â€¯0.13 GPa, respectively. No significant cytotoxicity for ZrO2 nanoparticles was observed when tested with mouse fibroblast cells (L929), suggesting that the synthesized ZrO2 nanoparticle is biocompatible and safe for environmental applications.