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Magnetic bimetallic nanospinels (MFe 2 O 4 ; M=Cu, Zn, Ni and Co) of size ranging between 15-30 nm were synthesized by facile and viable sol-gel method. The analysis of Fourier Transform Infrared Spectra of all the samples demonstrated formation of M-O bond in spinel structure. Structural exploration of all the nano materials using Powder X-Ray Diffraction and High Resolution Transmission Electron Microscopy revealed formation of single phase cubic spinel structure. All the materials exhibited magnetic temperament with high surface area (92-151 m 2 /g). Furthermore, band gap calculated from diffuse reflectance spectra was quite narrow (1.26-2.08eV) for all the samples, hence ferrites could act as visible light driven photocatalyst.The prepared nanospinels were proposed to be promising heterogeneous photo-Fenton catalyst under visible light for the degradation of organic pollutants. The catalytic results revealed that rate of reaction was significantly influenced by the cation in the spinel structure as degradation order was observed to be CuFe 2 O 4 (k=0.286 min -1 ) >ZnFe 2 O 4 (k=0.267 min -1 ) > NiFe 2 O 4 (k=0.138 min -1 ) > CoFe 2 O 4 (k=0.078 min -1 ). The reaction conditions were optimized for all the ferrites as the photodegradation was influenced by ferrite dosage (0.25-1.00 g/L), pH (2)(3)(4)(5) and H 2 O 2 concentration (4-27 mM). The experimental data disclosed that activity of ferrite was sensitive to sintering temperature. The materials displayed remarkable stability in the reaction as it could be magnetically separated using external magnet and recycled up to 4 consecutive cycles. There was no significant loss in activity of all the material demonstrating an excellent ability of ferrites to remove organic pollutants from wastewater.

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Directed evolution is being used increasingly in industrial and academic laboratories to modify and improve commercially important enzymes. Laboratory evolution is thought to make its biggest contribution in explorations of non-natural functions, by allowing us to distinguish the properties nurtured by evolution. In this review we report the significant advances achieved with respect to the methods of biocatalyst improvement and some critical properties and applications of the modified enzymes. The application of directed evolution has been elaborately demonstrated for protein solubility, stability and catalytic efficiency. Modification of certain enzymes for their application in enantioselective catalysis has also been elucidated. By providing a simple and reliable route to enzyme improvement, directed evolution has emerged as a key technology for enzyme engineering and biocatalysis.

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