Harvesting micro algae

Abstract

A reusable composite paramagnetic particle may comprise a paramagnetic core encased by a protective material to which is grafted a tendril layer comprising a plurality of polymeric chains. The polymeric chains may be designed to interact with a microorganism. The interaction between the microorganism and the polymeric chain may be electrostatic. The nanoparticle may be used in a method to isolate or recover microorganisms from solutions using an externally applied magnetic field.

1 . A composite particle comprising:
 a core;   a protective shell encasing said core; and   a tendril layer, further comprising a plurality of polymeric chains attached to the protective shell.   
     
     
         2 . The composite particle of  claim 1 , wherein the core further comprises a paramagnetic material. 
     
     
         3 . The composite particle of  claim 2 , wherein the paramagnetic material comprises iron oxide. 
     
     
         4 . The composite particle of  claim 3 , wherein the core material comprises Fe 2 O 3 . 
     
     
         5 . The composite particle of  claim 3 , wherein the core material comprises Fe 3 O 4 . 
     
     
         6 . The composite particle of  claim 1 , wherein the protective shell comprises silica. 
     
     
         7 . The composite particle of  claim 1 , wherein the polymeric chains are hydrophilic. 
     
     
         8 . The composite particle of  claim 7 , wherein the polymeric chains have a net positive charge. 
     
     
         9 . The composite particle of  claim 7 , wherein the polymeric chains have a net negative charge. 
     
     
         10 . The composite particle of  claim 7 , wherein the polymeric chains have no net charge. 
     
     
         11 . A method of recovering a microorganism from a solution comprising:
 providing a microorganism in a solution;   adding a composite paramagnetic particle, wherein the composite particle has a silica encased iron oxide core, and polymeric chains grafted to the silica;   allowing the composite particles to be suspended in the solution;   waiting sufficient time to allow the composite particles and microorganisms to interact;   applying an external magnetic field to the solution; and   recovering the composite particles and microorganism suspension.   
     
     
         12 . The method of  claim 11 , wherein the microorganism is microalgae. 
     
     
         13 . The method of  claim 11 , wherein the solution is drinking water. 
     
     
         14 . The method of  claim 12 , wherein the microalgae are producing biofuels. 
     
     
         15 . The method of  claim 11 , wherein the composite particles are reused particles. 
     
     
         16 . A composite particle comprising:
 a crystalline iron oxide core,   a silica shell coating the core; and   a tendril layer comprising a plurality of polymeric chains, wherein the polymeric chains are grafted to or grafted from the silica shell.   
     
     
         17 . The particle of  claim 16 , wherein the polymeric chains are grafted onto the silica shell by one or more of step-growth polymerization, chain-growth polymerization, and controlled/living polymerization. 
     
     
         18 . The method of  claim 17 , wherein the “controlled/living” polymerization method is one or more of reversible addition fragmentation transfer polymerization, atom transfer radical polymerization, ring-opening polymerization, anionic polymerization and cationic polymerization. 
     
     
         19 . The particle of  claim 16 , wherein the polymeric chains are grafted onto the silica shell by reversible addition fragmentation transfer polymerization. 
     
     
         20 . The particle of  claim 19 , wherein the silica coating is modified by 3-Aminopropyltriethoxysilane or 5,6-Epoxyhexyltriethoxysilane prior to grafting the polymeric chains.