Abstract: There is disclosed, a desalination apparatus making use of a particles including covalently bonded functionalized magnetic nanoparticles coupled to a complexing agent. For example, the complexing agent may include a crown ether. The particles are optionally used for removing salt from water, for example sea water. The apparatus optionally includes a magnet for magnetic filtering, concentrating and/or removing the particles and/or contaminant (e.g., salt). In some embodiments, the salt is then separated back from the particles using UV light. The remaining unclarified water may be washed out with the contaminant and/or used for salt production and/or disposed of (e.g., dumped back to the sea). Optionally, the particles are regenerated. For example, the regenerated particulars may be reused for further desalination steps (e.g., further salt removal from the clarified water) to clarify new input water. Covalently bonded functionalized magnetic nanoparticles coupled to a complexing agent are also disclosed.