In-situ precipitation of ultra-stable nano-magnetite slurry

Magnetically Induced Aggregation of Iron Oxide Nanoparticles for Carrier Flotation Strategies

On the nanoscale, iron oxides can be used for multiple applications ranging from medical treatment to biotechnology. We aimed to utilize the specific properties of these nanoparticles for new process concepts in flotation. Magnetic nanoparticles were synthesized by alkaline coprecipitation, leading to a primary particle size of 9 nm, and coated with oleate. The nanomaterial was characterized for its superparamagnetism and its colloidal stability at different ionic strengths, with and without an external magnetic field. The nanomaterial was used for model experiments on magnetic carrier flotation of microplastic particles, based on magnetically induced heteroagglomeration. We were able to demonstrate the magnetically induced aggregation of the nanoparticles which allows for new flotation strategies. Since the nanomaterial has zero remanent magnetization, the agglomeration is reversible which facilitates the process control. Magnetic carrier flotation based on iron oxide nanoparticles can pave the way to promising new recycling processes for microplastic wastes.

Polyethylene Glycol Coated Magnetic Nanoparticles: Hybrid Nanofluid Formulation, Properties and Drug Delivery Prospects

Magnetic nanoparticles (MNPs) are widely used materials for biomedical applications owing to their intriguing chemical, biological and magnetic properties. The evolution of MNP based biomedical applications (such as hyperthermia treatment and drug delivery) could be advanced using magnetic nanofluids (MNFs) designed with a biocompatible surface coating strategy. This study presents the first report on the drug loading/release capability of MNF formulated with methoxy polyethylene glycol (referred to as PEG) coated MNP in aqueous (phosphate buffer) fluid. We have selected MNPs (NiFe₂O4, CoFe₂O4 and Fe₃O₄) coated with PEG for MNF formulation and evaluated the loading/release efficacy of doxorubicin (DOX), an anticancer drug. We have presented in detail the drug loading capacity and the time-dependent cumulative drug release of DOX from PEG-coated MNPs based MNFs. Specifically, we have selected three different MNPs (NiFe₂O₄, CoFe₂O₄ and Fe₃O₄) coated with PEG for the MNFs and compared their variance in the loading/release efficacy of DOX, through experimental results fitting into mathematical models. DOX loading takes the order in the MNFs as CoFe₂O₄ > NiFe₂O₄ > Fe₃O₄. Various drug release models were suggested and evaluated for the individual MNP based NFs. While the non-Fickian diffusion (anomalous) model fits for DOX release from PEG coated CoFe₂O₄, PEG coated NiFe₂O₄ NF follows zero-order kinetics with a slow drug release rate of 1.33% of DOX per minute. On the other hand, PEG coated NiFe₂O₄ follows zero-order DOX release. Besides, several thermophysical properties and magnetic susceptibility of the MNFs of different concentrations have been studied by dispersing the MNPs (NiFe₂O₄, CoFe₂O₄ and Fe₃O₄) in the base fluid at 300 K under ultrasonication. This report on the DOX loading/release capability of MNF will set a new paradigm in view that MNF can resolve problems related to the self-heating of drug carriers during mild laser treatment with its thermal conducting properties.

On-stream mineral identification of tailing slurries of tungsten via NIR and XRF data fusion measurement techniques

Mineral flotation processes are controlled by monitoring the grade of the present minerals. The economy of the flotation process can be significantly improved by on-line analysis of minerals in a slurry. However, online and quantitative mineral identification of slurries is challenging. Industrial developers are demanding novel ideas enabling differentiation between minerals with similar elemental contents, such as scheelite and fluorite or gangue minerals, since they have different flotation properties. The primary focus of this research is the measurement of mineral contents from the elemental concentrations acquired by an on-stream slurry analyser based on X-ray fluorescence (XRF) and near-infrared spectroscopy (NIR). In this work, the samples in the test were obtained from a tungsten dressing plant. It is vital to master the mineral grade for controlling the flotation plant. The XRF parameters were optimised by Monte Carlo simulation, and the XRF and NIR data fusion was discussed. A multivariate statistical method called the least squares support vector machine (LS-SVM) was employed to perform the element-to-mineral conversion. The results show that such data integrations enable on-stream and quantitative identification of slurry mineral contents, especially for scheelite, wolframite, fluorite and calcite, which are essential minerals in tungsten ore beneficiation. This technique can lead to many benefits, such as rapid control of concentrate quality, enhanced recovery and savings in money, time, energy and workforce.

Physical Characterization of Halofantrine-Encapsulated Fat Nanoemulsions

We report the colloidal characterization of halofantrine (Hf)-laden soybean oil fat emulsions. Hf increased the zeta potential, at all pH values, of the fat emulsions. Concomitant with this, the isoelectric point (i.e.p.) of the emulsion increased to higher pH values. The emulsion was destabilized by a small amount of Hf; interestingly, however, this was ameliorated by increasing the amount of Hf. The particle size and polydispersity of the fat emulsion reflected this with a small Hf concentration resulting in a significant increase in both particle size and polydispersity, but less so as the Hf concentration was increased. Emulsions lost stability as the pH approached the i.e.p. and this effect was greatest for the small Hf concentration emulsions. Cryogenic transmission electron microscopy showed the presence of beading or string-like behavior leading to gross distortions of the spherical shape for highly unstable emulsions. We conclude that to maintain good stability for Hf-laden soybean oil emulsions, the pH of the emulsion should be kept away from its i.e.p, and also that the drug concentration should be maintained at a relatively high value.

Fabrication of magnetite nanocrystals in alcohol/water mixed solvents: catalytic and colloid property evaluation

Size tailoring in alcohol–water mixed solvents produces small magnetite nanocrystals with appreciably high catalytic activities that form ultrastable colloids when suspended in water.

Colloidal properties of water dispersible magnetite nanoparticles by photon correlation spectroscopy

Temperature and time trend analyses by light scattering technique over a year on aqueous ferrofluid, synthesized by coprecipitation technique, showed unambiguously that they are ultrastable and monodisperse.