No abstract

Metal-organic frameworks (MOFs), a class of porous hybrid materials composed of metal ions and organic ligands, have been studied for a variety of applications. In this work, for the first time, magnetic MOFs are developed for lipase immobilization. A general one-step in situ hydrothermal route is developed for the construction of MOFs encapsulating superparamagnetic Fe 3 O 4 nanoparticles. The integration of Fe 3 O 4 nanoparticles into MOFs exhibit many interesting inherent properties including porous nature, easy functionalization as well as strong superparamagnetism. Here Candida Rugosa Lipase (CRL) is covalently attached to amino-rich magnetic MOFs. The resulting magnetic MOFs are characterized by means of field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM). Then the enzymatic activities of the immobilized CRL are compared with free CRL. The immobilized CRL presented wider pH tolerance and excellent thermal stability than free CRL. The Michaelis-Menten kinetic constant (K m ) and maximum reaction velocity (V max ) for both free and immobilized lipase are investigated. The loading amount of CRL on magnetic MOFs was 280 mg/g support and the immobilized CRL was efficiently recycled up to nine cycles.

No abstract

No abstract

A novel and inexpensive approach was adopted to develop a magnetic nanocomposite for the adsorption of cationic dye from an aqueous solution. This nanocomposite, which was based on a superparamagnetic iron oxide nanocore, was functionalized with a hydrophilic coating of polyaniline (PANI). The nanoparticle size, colloidal stability, surface chemistry, and magnetic properties were studied extensively by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. The polymeric functionalized magnetic nanocomposite had an average core size of 20-40 nm and a shell size of 6-10 nm. To evaluate the potential of such nanocomposites for dye adsorption, malachite green (MG) was exposed with different operational parameters, such as the pH, temperature, initial concentration of the dye, contact time, and reusability. The rate of the adsorption followed pseudo-second-order kinetics with the adsorption isotherm fit the Langmuir isotherm model well. The maximum adsorption capacity was 240 mg of MG/g of adsorbent.