Poly (vinyl) alcohol stabilized aqueous ferrofluids (PVA-ff) were used as nanotemplates for the crystallization of calcium hydroxyapatite (HAp). Four sets of PVA-ff-HAp nanocomposites were synthesized using 20, 40, 60 and 80 ml of PVA-ff for the same initial constituents of HAp. Various physico-chemical analyses suggest that the HAp lattice structure accommodates PVA-ff to a certain extent, beyond which the magnetic intra-molecular interactions predominate and PVA-ff starts to be pushed out of the HAp matrix. The in situ incorporation of PVA-ff during HAp synthesis results in a novel magnetic biomaterial with potential applications as targeted delivery vehicles.

Persistent organic substances in wastewater are creating serious problems to the living world as well as to the environment, thereby creating huge detrimental impact on the ecosystem. In view of the grave situation, removal of the persistent organic substances from wastewater effluent holds a great promise to balance the ecosystem and to sustain societal impact value. In this respect, perovskite based photocatalysts have achieved remarkable attention to the scientific community due to their unique structural features and flexibility of composition. Again, surface polarization and electric dipole-dipole interaction in the perovskite material make them attractive for photocatalytic application. This review paper summarized the photocatalytic activity of perovskite materials and their modification to enhance catalytic activity for wastewater treatment. The modification in perovskite has been done to reduce bandgap energy for enhanced visible light activity, separation of charge carriers for their long lifetime, and fast photocatalytic reaction. The recent investigation of ABO 3 type perovskite, layered perovskite, and halide type of perovskite photocatalysts have been discussed detailly. The modification of corresponding perovskites by doped and formation of heterojunction is investigated carefully. The formation and identification of reactive oxygen species (ROS) and their degradation mechanism by trapping experiment and ESR technique has been summarized here. Finally, large scale with energy and environmental related research should be processed for a permanent solution of wastewater problem.

Recently non-harmful nanomaterials have acquired critical significant attention in wastewater treatment containing organic pollutants especially toxic and hazardous dyes. In this regard, a low cost and eco friendly method has been investigated for the green synthesis of alumina nanoparticles (Al2O3 NPs). The alumina nanoparticles were synthesized using an aqueous extract of Psidium guajava leaf as a potential stabilizing agent. The UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) techniques were used to characterize the synthesized nanoparticles. The absorption at 281 nm confirmed the formation of alumina nanoparticles. The FTIR spectra and XRD analysis confirmed the presence of various functional groups and crystalline structures of Al2O3 NPs during the synthesis. The spectrum clearly indicates the organic moieties in Psidium guajava extract are responsible for the biosynthesis of Al2O3 NPs. The suface morphology of Al2O3 NPs was confirmed by SEM and EDS studies. Besides this, the removal of methylene blue through adsorption and kinetic study was also reported.